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Seoul National University is a national research university founded in 1946, located in Seoul, the capital of Korea. It is widely considered to be the most prestigious university in the country.The university comprises sixteen colleges and six professional schools, and a student body of about 28,000. It has two campuses in Seoul: the main campus in Gwanak and the medical campus in Jongno. According to data compiled by KEDI, the university spends more on its students per capita than any other university in the country that enrolls at least 10,000.The university holds a memorandum of understanding with over 700 academic institutions in 40 countries, the World Bank, and the country's first ever general academic exchange program with the University of Pennsylvania. The Graduate School of Business offers dual master's degrees with Duke University, ESSEC Business School, and the Peking University, double-degrees at the MIT Sloan School of Management and Yale School of Management, and MBA-, MS-, and PhD-candidate exchange programs with universities in ten countries on four continents. The university's international faculty headcount is 242 or 4% of the total. Nobel laureate Paul Crutzen and Fields Medal recipient Hironaka Heisuke are on the faculty roster. Wikipedia.

Kim Y.C.,Seoul National University
Archives of Pharmacal Research | Year: 2010

Neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, ischemia and traumatic injury are characterized by progressive neuronal loss and dysfunction. Many neuroprotective agents modulating cellular responses against noxious stimuli, such as oxidative stresses, thereby having anti-inflammatory and antiapoptotic activity have been studied to develop the therapeutics for neurodegenerative diseases. Recently, the phenolic compounds widely spread in medicinal plants have drawn attention as potential neuroprotective agents. In this review, naturally-occuring neuroprotective phenolics and their underlying mechanisms of neuroprotective actions are summarized. © 2010 The Pharmaceutical Society of Korea and Springer Netherlands.

RENO (Reactor Experiment for Neutrino Oscillation) made a definitive measurement of the smallest neutrino mixing angle θ13 in 2012, based on the disappearance of reactor electron antineutrinos. The experiment has obtained a more precise value of the mixing angle and the first result on neutrino mass difference Δmee 2 from an energy and baseline dependent reactor neutrino disappearance using ∼500 days of data. Based on the ratio of inverse-beta-decay (IBD) prompt spectra measured in two identical far and near detectors, we obtain sin2⁡(2θ13)=0.082±0.009(stat.)±0.006(syst.) and |Δmee 2|=[2.62−0.23 +0.21(stat.)−0.13 +0.12(syst.)]×10−3 eV2. An excess of reactor antineutrinos near 5 MeV is observed in the measured prompt spectrum with respect to the most commonly used models. The excess is found to be consistent with coming from reactors. A successful measurement of θ13 is also made in an IBD event sample with a delayed signal of neutron capture on hydrogen. A precise value of θ13 would provide important information on determination of the leptonic CP phase if combined with a result of an accelerator neutrino beam experiment. © 2016 The Author

The fluvial geochemical data of major rivers draining the Himalayas and the Tibetan Plateau (HTP) are compiled from literature and supplemented with data from the author's group to explore the spatial variability in the major element and strontium isotopic compositions and in rates of silicate weathering and concomitant drawdown of atmospheric CO2. The results indicate that carbonate weathering dominates the major element composition of these rivers, and when the silicate contributions are carefully separated, there is spatial variability within the HTP system. Silicate contributions are highest in the rivers of the Himalayan syntaxes and in the Yamuna, Alaknanda-Bhaghirathi and Kosi tributaries of the Ganges. The 87Sr/86Sr ratios are especially radiogenic in the Ganges tributaries but the values do not necessarily correlate with the relative input from silicate weathering. Even in the Yamuna tributary of the Ganges where rates of CO2 consumption by silicate weathering are several times those of the rivers of the eastern Tibetan Plateau, the rates are comparable to the rivers draining the Andes. Thus, the Ganges tributaries supply uniquely radiogenic 87Sr to the ocean but cannot be considered anomalous in terms of silicate weathering rates in comparison to other major rivers draining orogenic zones. © The Geological Society of London 2010.

Lee H.O.,Seoul National University
Molecules and cells | Year: 2010

Fibroblast growth factor binding protein 1 (FGFBP1) is expressed in various tumors and may serve as a diagnostic marker and/or a therapeutic target. Previous studies suggested FGFBP1 functions as an angiogenic switch molecule by regulating the activity of FGF2, and it was later found to associate with a broad spectrum of FGFs. To study FGFBP1, we used zebrafish, in which the function of extracellular matrix protein can be easily studied in intact tissues or organisms. When Fgfbp1 expression was knocked down, morphants manifested massive cell death and structural abnormalities. Cell death was most prominent in the brain and the neural tube, but not limited to those regions. These findings suggest that the primary function of Fgfbp1 may be to sustain cellular survival throughout embryogenesis. For comparison, the expression of fgf2 was limited to the early stage of embryogenesis and fgf2 morphants showed more severe phenotype, with high morbidity before reaching 14-somites. Taken together, our work reveals the physiologic function of Fgfbp1, and that its function could be exerted in a Fgf2-independent manner.

Macronutrient balance is an important determinant of fitness in many animals, including insects. Previous studies have shown that altering the concentrations of yeast and sugar in the semi-synthetic media has a profound impact on lifespan in Drosophila melanogaster, suggesting that dietary protein:carbohydrate (P:C) balance is the main driver of lifespan and ageing processes. However, since yeast is rich in multiple nutrients other than proteins, this lifespan-determining role of dietary P:C balance needs to be further substantiated through trials using a chemically-defined, synthetic diet. In the present study, the effects of dietary P:C balance on lifespan and fecundity were investigated in female D. melanogaster flies fed on one of eight isocaloric synthetic diets differing in P:C ratio (0:1, 1:16, 1:8, 1:4, 1:2, 1:1, 2:1 or 4:1). Lifespan and dietary P:C ratio were related in a convex manner, with lifespan increasing to a peak at the two intermediate P:C ratios (1:2 and 1:4) and falling at the imbalanced ratios (0:1 and 4:1). Ingesting nutritionally imbalanced diets not only caused an earlier onset of senescence but also accelerated the age-dependent increase in mortality. Egg production was suppressed when flies were fed on a protein-deficient food (0:1), but increased with increasing dietary P:C ratio. Long-lived flies at the intermediate P:C ratios (1:2 and 1:4) stored a greater amount of lipids than those short-lived ones at the two imbalanced ratios (0:1 and 4:1). These findings provide a strong support to the notion that adequate dietary P:C balance is crucial for extending lifespan in D. melanogaster and offer new insights into how dietary P:C balance affects lifespan and ageing through its impacts on body composition. © 2015 Elsevier Ltd.

Bang Y.-J.,Seoul National University
Therapeutic Advances in Medical Oncology | Year: 2011

Tyrosine kinases have a crucial role as key regulators of signaling pathways that influence cell differentiation and growth. Dysregulation of tyrosine kinase-mediated signaling is understood to be an important oncogenic driver. Genetic rearrangements involving the tyrosine kinase anaplastic lymphoma kinase (ALK) gene occur in non-small cell lung cancer (NSCLC), anaplastic large cell lymphomoas, inflammatory myofibroblastic tumors, and other cancers. Cells with abnormal ALK signaling are sensitive to ALK inhibitors such as crizotinib. This review will highlight the discovery of the fusion between echinoderm microtubuleassociated protein-like 4 (EML4) and ALK as an oncogenic driver, recognition of other ALK gene rearrangements in NSCLC, and the confirmation that crizotinib is an effective treatment for patients with ALK-positive NSCLC. Work is underway to further define the role for crizotinib in the treatment of ALK-positive lung cancer and other cancers and to investigate the molecular mechanisms for resistance to ALK inhibition with crizotinib. © 2011 The Author(s).

Trippe S.,Seoul National University
Journal of the Korean Astronomical Society | Year: 2014

The jet production efficiency of radio galaxies can be quantified by comparison of their kinetic jet powers Pjet and Bondi accretion powers PB. These two parameters are known to be related linearly, with the jet power resulting from the Bondi power by multiplication with an efficiency factor of order 1%. Using a recently published (Nemmen & Tchekhovskoy 2014) high-quality sample of 27 radio galaxies, I construct a PB-Pjet diagram that includes information on optical AGN types as far as available. This diagram indicates that the jet production efficiency is a function of AGN type: Seyfert 2 galaxies seem to be systematically (with a false alarm probability of 4.3 × 10-4) less efficient, by about one order of magnitude, in powering jets than Seyfert 1 galaxies, LINERs, or the remaining radio galaxies. This suggests an evolutionary sequence from Sy 2s to Sy 1s and LINERs, controlled by an interplay of jets on the one hand and dust and gas in galactic nuclei on the other hand. When taking this effect into account, the PB-Pjet relation is probably much tighter intrinsically than currently assumed. © 2014. The Korean Astronomical Society. All rights reserved.

Trippe S.,Seoul National University
Journal of the Korean Astronomical Society | Year: 2014

Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich- Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation. © 2014 The Korean Astronomical Society. All Rights Reserved.

Chung J.W.,Seoul National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2013

Conventional triple therapy (CT) for Helicobacter pylori infection fails in up to one-third of patients. Sequential therapy (ST) seem be more effective than CT in other countries. However, there is no systemic literature review that directly compares CT and ST in Korea. The aim of this study was to compare ST with CT for H. pylori infection in Korea. Six randomized, prospective controlled trials were used to compare 10-day ST and 7- to 14-day CT in treatment-naive patients with documented H. pylori infection in Korea. Pooled eradication rates and OR with 95% CI were calculated. The intention-to-treat eradication rates of H. pylori involving 1,529 patients were 79.7% (95% CI, 76.8-82.5%) for ST (n=754) and 68.1% (95% CI, 64.8-71.4%) for CT (n=775) (OR, 1.838; p<0.001). The per-protocol eradication rate of H. pylori involving 1,366 patients was 86.4% (95% CI, 83.3-88.5%) for ST (n=682) and 76.0% (95% CI, 72.8-79.2%) for CT (n=684) (OR, 1.974; p<0.001). Ten-day ST was superior to CT in terms of eradicating H. pylori infection. Therefore, ST should be considered as a first-line therapy in Korea. However, ST did not achieve a sufficient eradication rate. More effective therapy should be developed.

Park H.-W.,Harvard University | Park H.-W.,Seoul National University | Tantisira K.G.,Harvard University | Weiss S.T.,Harvard University | Weiss S.T.,Partners Center for Personalized Genetic Medicine
Annual Review of Pharmacology and Toxicology | Year: 2015

The response to drug treatment in asthma is a complex trait and is markedly variable even in patients with apparently similar clinical features. Pharmaco-genomics, which is the study of variations of human genome characteristics as related to drug response, can play a role in asthma therapy. Both a traditional candidate-gene approach to conducting genetic association studies and genome-wide association studies have provided an increasing list of genes and variants associated with the three major classes of asthma medications: β2-agonists, inhaled corticosteroids, and leukotriene modifiers. Moreover, a recent integrative, systems-level approach has offered a promising opportunity to identify important pharmacogenomics loci in asthma treatment. However, we are still a long way away from making this discipline directly relevant to patients. The combination of network modeling, functional validation, and integrative omics technologies will likely be needed to move asthma pharmacogenomics closer to clinical relevance. ©2015 by Annual Reviews. All rights reserved.

Cho Y.M.,Seoul National University | Fujita Y.,Asahikawa University | Kieffer T.J.,University of British Columbia
Annual Review of Physiology | Year: 2014

Glucagon-like peptide-1 (GLP-1), an incretin hormone secreted primarily from the intestinal L-cells in response to meals, modulates nutrient homeostasis via actions exerted in multiple tissues and cell types. GLP-1 and its analogs, as well as compounds that inhibit endogenous GLP-1 breakdown, have become an effective therapeutic strategy for many subjects with type 2 diabetes. Here we review the discovery of GLP-1; its synthesis, secretion, and elimination from the circulation; and its multiple pancreatic and extrapancreatic effects. Finally, we review current options for GLP-1-based diabetes therapy, including GLP-1 receptor agonism and inhibition of GLP-1 breakdown, as well as the benefits and drawbacks of different modes of therapy and the potential for new therapeutic avenues. © Copyright ©2014 by Annual Reviews. All rights reserved.

Cha Y.,Seoul National University
British Journal of Cancer | Year: 2016

Background:The association between the CpG island methylator phenotype (CIMP) and clinical outcomes in metastatic colorectal cancer remains unclear. We investigated the prognostic impact of CIMP in patients with metastatic colorectal cancer treated with systemic chemotherapy.Methods:Eight CIMP-specific promoters (CACNA1G, IGF2, NEUROG1, RUNX3, SOCS1, CDKN2A, CRABP1, and MLH1) were examined. The CIMP status was determined by the number of methylated promoters as high (⩾5), low (1–4), and negative (0).Results:A total of 153 patients were included (men/women, 103/50; median age, 61 years; range, 22–80 years). The CIMP status was negative/low/high in 77/ 69/7 patients, respectively. Overall survival (OS) was significantly different among the three CIMP groups, with median values of 35.7, 22.2, and 9.77 months for the negative, low, and high groups, respectively (P<0.001). For patients treated with fluoropyrimidine and oxaliplatin first-line chemotherapy (N=128), OS and progression-free survival (PFS) were significantly different among the three CIMP groups; the median OS was 37.9, 23.8, and 6.77 months for the negative, low, and high groups, respectively (P<0.001), while the median PFS was 9.97, 7.87, and 1.83 months, respectively (P=0.002). Response rates were marginally different among the three CIMP groups (53.4% vs 45.1% vs 16.7%, respectively; P=0.107). For patients treated with fluoropyrimidine and irinotecan second-line chemotherapy (N=86), only OS showed a difference according to the CIMP status, with median values of 20.4, 13.4, and 2.90 months for the negative, low, and high groups, respectively (P<0.001).Conclusions:The CIMP status is a negative prognostic factor for patients with metastatic colorectal cancer treated with chemotherapy.British Journal of Cancer advance online publication 16 June 2016; doi:10.1038/bjc.2016.176 www.bjcancer.com. © 2016 Cancer Research UK

Min S.-K.,CSIRO | Son S.-W.,Seoul National University
Journal of Geophysical Research: Atmospheres | Year: 2013

It has been suggested that the Hadley cell has been widening during the past three decades in both hemispheres, but attribution of its cause(s) remains challenging. By applying an optimal fingerprinting technique to 7 modern reanalyses and 49 coupled climate models participating in the CMIP3 and CMIP5, here we detect an influence of human-induced stratospheric ozone depletion on the observed expansion of the Hadley cell in the Southern Hemisphere (SH) summer. The detected signal is found to be separable from other external forcings that include greenhouse gases (GHGs), confirming a dominant role of stratospheric ozone in the SH summer climate change. Our results are largely insensitive to observational and model uncertainties, providing additional evidence for a human contribution to the atmospheric circulation changes. © 2013. American Geophysical Union. All Rights Reserved.

Park J.M.,Seoul National University
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2011

We investigated the effect of mixing high- and low-energy photon beams on the quality of intensity-modulated radiation therapy (IMRT) plans for patients with prostate cancer. Three different plans for each of twenty patients were generated using either 6 MV or 15 MV alone, and both 6 and 15 MV beams. All the planning parameters, goals, and constraints were set to be identical except beam energy. The dose distributions were similar in terms of target coverage, conformity, and homogeneity regardless of beam energy. The V(70Gy) of rectal wall in 6 MV, 15 MV and mixed-energy plans was 16.7%, 17.9%, and 16.3%, respectively, while V(40Gy) was 55.6%, 53.2%, and 50%. The mean dose to femoral heads in 6 MV, 15 MV, and mixed-energy plans were 31.7 Gy, 26.3 Gy, and 26.2 Gy, respectively. The integral dose of 6 MV plans was 7% larger than those of 15 MV or mixed-energy plans. These results indicated that mixed-energy IMRT plans could take advantage of the dosimetric characteristics of low- and high-energy beams. Even though the reduction of dose to the organs at risk may not be clinically relevant, mixing energy in an IMRT plan for deep-seated tumors can improve the overall plan quality.

Shim Y.,Carnegie Mellon University | Shim Y.,Seoul National University | Kim H.J.,Carnegie Mellon University | Kim H.J.,Korea Institute for Advanced Study
ACS Nano | Year: 2010

Supercapacitors composed of carbon nanotube (CNT) micropores in the room-temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI+BF4 -) are studied via molecular dynamics (MD) computer simulations. It is found that the distribution of RTIL ions inside the micropore varies significantly with the pore size. Internal solvation of small (6,6) and (7,7) CNTs with an electrified interior wall is effected almost exclusively via counterions. Surprisingly, these counterions, even though they all have the same charge, lead to a charge density characterized by multiple layers with alternating signs. This intriguing feature is attributed to the extended nature of RTIL ion charge distributions, which result in charge separation through preferential orientation inside the electrified nanotubes. In the case of larger (10,10) and (15,15) CNTs, counterions and co-ions develop multilayer solvation structures. The specific capacitance normalized to the pore surface area is found to increase as the CNT diameter decreases from (15,15) to (7,7). As the pore size further reduces from (6,6) to (5,5), however, the specific capacitance diminishes rapidly. These findings are in excellent agreement with recent experiments with carbon-based materials. A theoretical model based on multiple charge layers is proposed to understand both the MD and experimental results. © 2010 American Chemical Society.

Kim S.-K.,Seoul National University | Kim S.-K.,Lawrence Berkeley National Laboratory
Journal of Physics D: Applied Physics | Year: 2010

Current needs for further advances in the nanotechnologies of information-storage and-processing devices have attracted a great deal of interest in spin (magnetization) dynamics in nanometre-scale patterned magnetic elements. For instance, the unique dynamic characteristics of non-uniform magnetic microstructures such as various types of domain walls, magnetic vortices and antivortices, as well as spin wave dynamics in laterally restricted thin-film geometries, have been at the centre of extensive and intensive researches. Understanding the fundamentals of their unique spin structure as well as their robust and novel dynamic properties allows us to implement new functionalities into existing or future devices. Although experimental tools and theoretical approaches are effective means of understanding the fundamentals of spin dynamics and of gaining new insights into them, the limitations of those same tools and approaches have left gaps of unresolved questions in the pertinent physics. As an alternative, however, micromagnetic modelling and numerical simulation has recently emerged as a powerful tool for the study of a variety of phenomena related to spin dynamics of nanometre-scale magnetic elements. In this review paper, I summarize the recent results of simulations of the excitation and propagation and other novel wave characteristics of spin waves, highlighting how the micromagnetic computer simulation approach contributes to an understanding of spin dynamics of nanomagnetism and considering some of the merits of numerical simulation studies. Many examples of micromagnetic modelling for numerical calculations, employing various dimensions and shapes of patterned magnetic elements, are given. The current limitations of continuum micromagnetic modelling and of simulations based on the Landau-Lifshitz-Gilbert equation of motion of magnetization are also discussed, along with further research directions for spin-wave studies. © 2010 IOP Publishing Ltd.

STUDY DESIGN:: Retrospective analysis.OBJECTIVE:: The object is to assess the correlation between whole lumbar lordosis and the segmental angle after anterior single-level lumbar interbody fusion (ALIF) for degenerative lumbar spondylolisthesis.SUMMARY OF BACKGROUND DATA:: The restoration of the segmental angle at lower lumbar spine is meaningful, considering it contributes approximately 60% of lumbar lordosis, and revision surgery due to flat back or adjacent segment pathology was necessary decades after the initial surgery. However, little is known about the change of whole lumbar curvature after single-level lower lumbar fusion surgery, especially for balanced spine.METHODS:: We included 41 consecutive patients (M:F=9:32; mean age, 59.8±9.3 y) with a single-level ALIF surgery for low-grade degenerative spinal spondylolisthesis, with C7-plumb line of <5 cm and ≥2 years follow-up period. The operated levels were L4-5 in 34 patients and L5-S1 in 7 patients. Whole lumbar lordosis (LL), segmental angle (SA), pelvic tilt and sacral slope were compared.RESULTS:: According to the Macnab criteria, a favorable outcome (excellent, 21; good, 15) was achieved in 36/41 (88%; excellent, 21; good, 15) patients. LL and SA were significantly changed from −50.8±9.9° to −54.6±11.1° and −15.6±6.1° to −18.7±5.1° (P<0.01), and a positive correlation (r=0.43, P=0.01) was observed between LL and SA at postoperative month 24. The changes to the pelvic tilt and sacral slope were not significant.CONCLUSION:: Whole lumbar sagittal alignment was influenced by single segmental angle. Therefore, obtaining adequate segmental lordosis is desirable considering effect on the whole spine for a long-time. © 2014 by Lippincott Williams & Wilkins, Inc.

Kwon S.,Seoul National University
Asia-Pacific Journal of Public Health | Year: 2011

This article examines the major elements of health care financing such as financial risk protection, resource generation, resource pooling, and purchasing and payment; provides key lessons; and discusses the challenges for health care financing systems of Asian countries. With the exception of Japan, Korea, Taiwan, and Thailand, most health care systems of Asia provide very limited financial risk protection. The role of public prepaid schemes such as tax and social health insurance is minimal, and out-of-pocket payment is a major source of financing. The large informal sector is a major challenge to the extension of population coverage in many low-income countries of Asia, which must seek the optimal mix of tax subsidy and health insurance for universal coverage. Implementation of effective payment systems to control the behavior of health care providers is also a key factor in the success of health care financing reform in Asia. © 2011 Asia-Pacific Academic Consortium for Public Health.

Hwang J.,Center for Research on Inner City Health | Shon C.,Seoul National University
BMJ Open | Year: 2014

Objective: To examine the relationship between socioeconomic status (SES) and type 2 diabetes using the Korea National Health and Nutrition Examination Survey (KNHANES) 2010-2012. Design: A pooled sample cross-sectional study. Setting: A nationally representative population survey data. Participants: A total of 14 330 individuals who participated in the KNHANES 2010-2012 were included in our analysis. Primary outcome: Prevalence of type 2 diabetes. Results: The relationship between SES and type 2 diabetes was assessed using logistic regression after adjusting for covariates including age, gender, marital status, region, body mass index, physical activity, smoking and high-risk drinking behaviour. After adjustment for covariates, our results indicated that individuals with the lowest income were more likely to have type 2 diabetes than those with the highest income (OR 1.35; 95% CI 1.08 to 1.72). In addition, lower educational attainment was an independent factor for a higher prevalence of type 2 diabetes in Korea. Conclusions: These findings suggest the need for developing a health policy to ameliorate socioeconomic inequalities, in particular income and education-related disparities in type 2 diabetes, along with risk factors at the individual level. In addition, future investigations of type 2 diabetes among Koreans should pay more attention to the social determinants of diabetes in order to understand the various causes of the condition.

Seo Y.,Seoul National University
Journal of Non-Newtonian Fluid Mechanics | Year: 2011

A new scaling function capable of modeling the yield stress behavior of electrorheological (ER) fluids through the full range of electric fields is proposed. In spite of its simple form, a comparison of the model predictions with experimental data for both ac and dc fields and the polarization model shows that the proposed model correctly predicts the yield stress behavior both quantitatively as well as qualitatively. © 2010 Elsevier B.V.

Chung M.S.,Seoul National University
Clinics in Orthopedic Surgery | Year: 2011

For hand surgeons, the treatment of children with congenital differences of the upper extremity is challenging because of the diverse spectrum of conditions encountered, but the task is also rewarding because it provides surgeons with the opportunity to impact a child's growth and development. An ideal classification of congenital differences of the upper extremity would reflect the full spectrum of morphologic abnormalities and encompass etiology, a guide to treatment, and provide prognoses. In this report, I review current classification systems and discuss their contradictions and limitations. In addition, I present a modified classification system and provide treatment principles. As our understanding of the etiology of congenital differences of the upper extremity increases and as experience of treating difficult cases accumulates, even an ideal classification system and optimal treatment strategies will undoubtedly continue to evolve. © 2011 by Th e Korean Orthopaedic Association.

Youn S.W.,Seoul National University
Clinics in Dermatology | Year: 2010

Increased sebum secretion has been known as one of the major pathogenic factors in the development of acne; however, objective sebum measurement methods have been developed only recently. We have limited information about the association of sebum secretion, and the development of acne. There continues to be controversy about the role of sebum in the development of acne. This contribution will discuss sebum measurement techniques and the results of recent studies on the relationship of sebum, facial cosmetic skin type, and acne. New therapeutic modalities for inflammatory acne aim to control seborrhea. Superficial chemical peels, laser treatment for inflammatory acne, and photodynamic therapy are used as adjunctive therapies for acne; however, their sebosuppressive effects are only temporary. © 2010 Elsevier Inc. All rights reserved.

Kim J.,Seoul National University
Korean journal of ophthalmology : KJO | Year: 2010

A 68-year-old woman presented with a visual field defect in her right eye. The fundus of her right eye showed multiple telangiectatic vessels, retinal hemorrhages, and subretinal exudates in the inferior peripheral retina. Nine months later, the subretinal exudates extended to the fovea despite treatment with laser photocoagulation. Cryotherapy was not possible at the time because of the posterior location of the retinal telangiectatic vessels. She was treated with a combination of photodynamic therapy (PDT) and intravitreal bevacizumab injection: three injections were given at 2-month intervals. After this combined therapy, her right fundus revealed a significant regression of abnormal retinal vessels and subretinal exudates. A fluorescein angiography showed no leakage from the abnormal retinal vessels. At 9 months after the combined therapy, she was able to maintain a stable visual acuity and visual field. This is the first case report that demonstrates the efficacy of the combined treatment of PDT and intravitreal bevacizumab injection in Coats's disease. This combined therapy is a kind of treatment modality for adult Coats' disease in cases which cryotherapy cannot be employed and are refractory to laser photocoagulation.

A robust detection of the tidally induced intrinsic alignments of the late-type spiral galaxies with high statistical significance is reported. From the spectroscopic galaxy sample of Sloan Digital Sky Survey DR7 compiled by Huertas-Company etal., which lists each galaxy's probabilities of being in five Hubble types, P(E), P(Ell), P(S0), P(Sab), P(Scd), we select the nearby large late-type spiral galaxies which have redshifts of 0 ≤ z ≤ 0.02, probabilities of P(Scd) ≥ 0.5, and angular sizes of D ≥ 7.92 arcsec. The spin axes of the selected nearby large late-type spiral galaxies are determined up to the two-fold ambiguity with the help of the circular thin-disk approximation, and their spatial correlations are measured as a function of the separation distance r. A clear signal of the intrinsic correlation as high as 3.4σ and 2.4σ is found at the separation distance of r ≈ 1 h -1Mpc and r ≈ 2 h -1Mpc, respectively. The comparison of this observational results with the analytic model based on the tidal torque theory reveals that the spin correlation function for the late-type spiral galaxies follows the quadratic scaling of the linear density correlation and that the intrinsic correlations of the galaxy spin axes are stronger than that of the underlying dark halos. We investigate a local density dependence of the galaxy spin correlations and found that the correlations are stronger for the galaxies located in dense regions having more than 10 neighbors within 2 h -1Mpc. We also attempt to measure a luminosity dependence of the galaxy spin correlations, but find that it is impossible with our magnitude-split samples to disentangle a luminosity from a redshift dependence. We provide the physical explanations for these observational results and also discuss the effects of possible residual systematics on the results. © 2011. The American Astronomical Society. All rights reserved.

Koh H.,Dong - A University | Chung J.,Seoul National University
Molecules and Cells | Year: 2012

Parkinson's disease (PD), the most prevalent neurodegenerative movement disorder, is characterized by an age-dependent selective loss of dopaminergic (DA) neurons. Although most PD cases are sporadic, more than 20 responsible genes in familial cases were identified recently. Genetic studies using Drosophila models demonstrate that PINK1, a mitochondrial kinase encoded by a PD-linked gene PINK1, is critical for maintaining mitochondrial function and integrity. This suggests that mitochondrial dysfunction is the main cause of PD pathogenesis. Further genetic and cell biological studies revealed that PINK1 recruits Parkin, an E3 ubiquitin ligase encoded by another PD-linked gene parkin, to mitochondria and regulates the mitochondrial remodeling process via the Parkin-mediated ubiquitination of various mitochondrial proteins. PINK1 also directly phosphorylates the mitochondrial proteins Miro and TRAP1, subsequently inhibiting mitochondrial transport and mitochondrial oxidative damage, respectively. Moreover, recent Drosophila genetic analyses demonstrate that the neuroprotective molecules Sir2 and FOXO specifically complement mitochondrial dysfunction and DA neuron loss in PINK1 null mutants, suggesting that Sir2 and FOXO protect mitochondria and DA neurons downstream of PINK1. Collectively, these recent results suggest that PINK1 plays multiple roles in mitochondrial quality control by regulating its mitochondrial, cytosolic, and nuclear targets. © 2012 The Korean Society for Molecular and Cellular Biology and Springer Netherlands.

Zhuo M.,Xian University of Science and Technology | Zhuo M.,Kings College | Zhuo M.,Seoul National University
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2014

Glutamate is the primary excitatory transmitter of sensory transmission and perception in the central nervous system. Painful or noxious stimuli from the periphery 'teach' humans and animals to avoid potentially dangerous objects or environments, whereas tissue injury itself causes unnecessary chronic pain that can even last for long periods of time. Conventional pain medicines often fail to control chronic pain. Recent neurobiological studies suggest that synaptic plasticity taking place in sensory pathways, from spinal dorsal horn to cortical areas, contributes to chronic pain. Injuries trigger long-term potentiation of synaptic transmission in the spinal cord dorsal horn and anterior cingulate cortex, and such persistent potentiation does not require continuous neuronal activity from the periphery. At the synaptic level, potentiation of excitatory transmission caused by injuries may be mediated by the enhancement of glutamate release from presynaptic terminals and potentiated postsynaptic responses of AMPA receptors. Preventing, 'erasing' or reducing such potentiation may serve as a new mechanism to inhibit chronic pain in patients in the future. © 2013 The Authors.

Chun J.,Seoul National University | Rainey F.A.,University of Alaska Anchorage
International Journal of Systematic and Evolutionary Microbiology | Year: 2014

The polyphasic approach used today in the taxonomy and systematics of the Bacteria and Archaea includes the use of phenotypic, chemotaxonomic and genotypic data. The use of 16S rRNA gene sequence data has revolutionized our understanding of the microbial world and led to a rapid increase in the number of descriptions of novel taxa, especially at the species level. It has allowed in many cases for the demarcation of taxa into distinct species, but its limitations in a number of groups have resulted in the continued use of DNA-DNA hybridization. As technology has improved, next-generation sequencing (NGS) has provided a rapid and cost-effective approach to obtaining whole-genome sequences of microbial strains. Although some 12 000 bacterial or archaeal genome sequences are available for comparison, only 1725 of these are of actual type strains, limiting the use of genomic data in comparative taxonomic studies when there are nearly 11 000 type strains. Efforts to obtain complete genome sequences of all type strains are critical to the future of microbial systematics. The incorporation of genomics into the taxonomy and systematics of the Bacteria and Archaea coupled with computational advances will boost the credibility of taxonomy in the genomic era. This special issue of International Journal of Systematic and Evolutionary Microbiology contains both original research and review articles covering the use of genomic sequence data in microbial taxonomy and systematics. It includes contributions on specific taxa as well as outlines of approaches for incorporating genomics into new strain isolation to new taxon description workflows. © 2014 IUMS.

To survive in hypoxic environments, organisms must be able to cope with redox imbalance and oxygen deficiency. The SIRT1 deacetylase and the HIF-1alpha transcription factor act as redox and oxygen sensors, respectively. Here, we found that SIRT1 binds to HIF-1alpha and deacetylates it at Lys674, which is acetylated by PCAF. By doing so, SIRT1 inactivated HIF-1alpha by blocking p300 recruitment and consequently repressed HIF-1 target genes. During hypoxia, SIRT1 was downregulated due to decreased NAD(+) levels, which allowed the acetylation and activation of HIF-1alpha. Conversely, when the redox change was attenuated by blocking glycolysis, SIRT1 was upregulated, leading to the deacetylation and inactivation of HIF-1alpha even in hypoxia. In addition, we confirmed the SIRT1-HIF-1alpha interaction in hypoxic mouse tissues and observed in vivo that SIRT1 has negative effects on tumor growth and angiogenesis. Our results suggest that crosstalk between oxygen- and redox-responsive signal transducers occurs through the SIRT1-HIF-1alpha interaction. Copyright (c) 2010 Elsevier Inc. All rights reserved.

The Xpert MTB/RIF assay was introduced for timely and accurate detection of tuberculosis (TB). The aim of this study was to determine the diagnostic accuracy and turnaround time (TAT) of Xpert MTB/RIF assay in clinical practice in South Korea. We retrospectively reviewed the medical records of patients in whom Xpert MTB/RIF assay using sputum were requested. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of pulmonary tuberculosis (PTB) and detection of rifampicin resistance were calculated. In addition, TAT of Xpert MTB/RIF assay was compared with those of other tests. Total 681 patients in whom Xpert MTB/RIF assay was requested were included in the analysis. The sensitivity, specificity, PPV and NPV of Xpert MTB/RIF assay for diagnosis of PTB were 79.5% (124/156), 100.0% (505/505), 100.0% (124/124) and 94.0% (505/537), respectively. Those for the detection of rifampicin resistance were 57.1% (8/14), 100.0% (113/113), 100.0% (8/8) and 94.9% (113/119), respectively. The median TAT of Xpert MTB/RIF assay to the report of results and results confirmed by physicians in outpatient settings were 0 (0-1) and 6 (3-7) days, respectively. Median time to treatment after initial evaluation was 7 (4-9) days in patients with Xpert MTB/RIF assay, but was 21 (7-33.5) days in patients without Xpert MTB/RIF assay. Xpert MTB/RIF assay showed acceptable sensitivity and excellent specificity for the diagnosis of PTB and detection of rifampicin resistance in areas with intermediate TB burden. Additionally, the assay decreased time to the initiation of anti-TB drugs through shorter TAT.

Ha K.-C.,Sejong University | Kye S.-H.,Seoul National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

In a recent paper [D. Chrušciński and F. A. Wudarski, Open Sys. Information Dyn. (unpublished)], it was conjectured that the entanglement witnesses arising from some generalized Choi maps are optimal. We show that this conjecture is true. Furthermore, we show that they provide a one-parameter family of indecomposable optimal entanglement witnesses. © 2011 American Physical Society.

Cho Y.K.,Seoul Veterans Hospital | Kim J.K.,Chung - Ang University | Kim W.T.,Seoul Veterans Hospital | Chung J.W.,Seoul National University
Hepatology | Year: 2010

No adequate randomized trials have been reported for a comparison between hepatic resection (HR) versus radiofrequency ablation (RFA) for the treatment of patients with very early stage hepatocellular carcinoma (HCC), defined as an asymptomatic solitary HCC <2 cm. For compensated cirrhotic patients with very early stage HCC, a Markov model was created to simulate a randomized trial between HR (group I) versus primary percutaneous RFA followed by HR for cases of initial local failure (group II) versus percutaneous RFA monotherapy (group III); each arm was allocated with a hypothetical cohort of 10,000 patients. The primary endpoint was overall survival. The estimates of the variables were extracted from published articles after a systematic review. In the parameter estimations, we assumed the best scenario for HR and the worst scenario for RFA. The mean expected survival was 7.577 years, 7.564 years, and 7.356 years for group I, group II, and group III, respectively. One-way sensitivity analysis demonstrated that group II was the preferred strategy if the perioperative mortality rate was greater than 1.0%, if the probability of local recurrence following an initial complete ablation was<1.9% or if the positive microscopic resection margin rate was>0.3%. The95%confidence intervals for the difference in overall survival were-0.18-0.18 years between group I and II, 0.06-0.36 years between group I and III, and 0.13-0.30 years between group II and III, respectively. Conclusion: Primary percutaneous RFA followed by HR for cases of initial local failure was nearly identical to HR for the overall survival of compensated cirrhotic patients with very early stage HCC. Copyright © 2010 by the American Association for the Study of Liver Diseases.

Suh S.,Seoul National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2012

Colonic diverticular bleeding cases account for 30-40% of the lower gastrointestinal bleeding, among which, 3-5% appear to be massive bleeding. The purpose of this study was to evaluate the risk factors for colonic diverticular bleeding diagnosed by colonoscopic examination. Among the 1,003 patients, who were identified to have colonic diverticulosis including sleeding by diverticulitis and diverticular bleeding coding search, 216 patients had diverculosis, and they were divided into two groups: one with diverticular bleeding, and the other without bleeding. We evaluated the potential risk factors for diverticular bleeding, based on age, gender, location of diverticulum, comorbidities related to atherosclerosis, smoking, alcohol and medications, and compared them between both groups. Among the 216 patients, we observed colonic diverticular bleeding in 35 patients (16.2%). The mean age of the bleeding group was significantly older than that of non-bleeding group. No difference was observed regarding gender ratio. Right colonic diverticula were common in both groups, but there were higher proportion of patients with bleeding in bilateral diverticuosis. Old age, bilateral diverticulosis, presence of atherosclerosis related diseases (hypertension, diabetes mellitus, ischemic heart disease, obesity), use of aspirin, NSAIDs and calcium channel blocker, increased the risk of bleeding. In a multivariate analysis, use of aspirin and bilateral diverticulosis were identified as independent risk factors for colonic diverticular bleeding. Since the patients who took aspirin and/or had bilateral colonic diverticulosis increased the risk of bleeding from divertuculi. As such, caution and education of patients are required.

Kaiser M.,Northumbria University | Kaiser M.,Seoul National University
Frontiers in Human Neuroscience | Year: 2012

The human connectome at the level of fiber tracts between brain regions has been shown to differ in patients with brain disorders compared to healthy control groups. Nonetheless, there is a potentially large number of different network organizations for individual patients that could lead to cognitive deficits prohibiting correct diagnosis. Therefore changes that can distinguish groups might not be sufficient to diagnose the disease that an individual patient suffers from and to indicate the best treatment option for that patient. We describe the challenges introduced by the large variability of connectomes within healthy subjects and patients and outline three common strategies to use connectomes as biomarkers of brain diseases. Finally, we propose a fourth option in using models of simulated brain activity (the dynamic connectome) based on structural connectivity rather than the structure (connectome) itself as a biomarker of disease. Dynamic connectomes, in addition to currently used structural, functional, or effective connectivity, could be an important future biomarker for clinical applications. © 2013 Kaiser.

This account of the author's contributions over his career attempts to sketch out a research arc that stretches all the way from very simple beginnings, taking inspiration from the steroidal trans-hydrindane problem, to the development of a general strategy for the stereoselective construction of cycloalkanecarboxylates via a folding and allylic strain controlled intramolecular ester enolate alkylation, with applications thereof to the total syntheses of natural products of modest complexity. Examination of the corresponding SN2′ version of this methodology led to a serendipitous discovery that ultimately produced the olefin geometry dependent intramolecular amide enolate alkylation. Applications and extensions of this methodology have enabled completely substrate-controlled asymmetric total syntheses of diverse medium-ring oxacyclic marine natural products, and a fortuitous discovery along the way involving an organoselenium-based method led to an intriguing biomimetic synthesis of Laurencia metabolites. Observations are made regarding aspects of a research career in retrospect. 1 Introduction 2 Intramolecular SN2 Enolate Alkylation 3 Intramolecular S N2′ Enolate Alkylation 4 Synthesis of α,α′- cis-Disubstituted Medium-Ring Oxa-cyclic Marine Natural Products 5 Synthesis of α,α′-trans-Disubstituted Medium-Ring Oxa-cyclic Marine Natural Products 6 General Synthetic Plan for Dioxabicyclic Bromoallene -Marine Natural Products Having either a 2,10-Dioxabi-cyclo[7.3.0]dodecene or 2,9-Dioxabicyclo[6.3.0]undecene Skeleton 7 Conclusion. © Georg Thieme Verlag Stuttgart · New York.

To investigate the significant determinants of health-related quality of life (HRQOL) and the association of the EULAR Sjögren's syndrome patient reported index (ESSPRI) with clinical parameters including HRQOL in Korean patients with primary Sjögren's syndrome (pSS) compared with non-SS sicca patients. We prospectively analysed 104 pSS and 42 non-SS sicca patients. Clinical data including Short Form 36 (SF-36) scores, self-assessments for symptoms and ESSPRI were cross-sectionally collected. Although most self-assessments and HRQOL statuses were comparable, different association patterns between HRQOL and symptoms were observed in pSS and non-SS sicca patients. pSS patients with low HRQOL had significantly higher ESSPRI scores [P = 7.6 × 10(-6) for physical component summary (PCS) subgroups and P = 0.0015 for mental component summary (MCS) subgroups] and ESSPRI scores showed a significant association with all SF-36 scales in pSS patients (all P ≤ 0.0020). Moreover, in multivariate linear regression analyses, ESSPRI (P = 0.035) and depression (P = 4.1 × 10(-14)) were significantly correlated with the PCS and the MCS, respectively. However, in the non-SS sicca group, xerostomia inventory (XI) scores were higher in the low PCS subgroup (P = 0.031) and this correlated with five SF-36 scales (all P ≤ 0.046). XI scores (P = 0.0039) and anxiety (P = 7.9 × 10(-10)) were the main determinants of the PCS and MCS, respectively. HRQOL levels were differentially associated with clinical facets in pSS and non-SS sicca patients, although the groups had similar clinical symptoms and HRQOL reduction. Because depression and ESSPRI are major determinants of HRQOL in Korean pSS patients, ESSPRI is suggested to be disease-specific for pSS.

Teiten M.-H.,Laboratoire Of Biologie Moleculaire Et Cellulaire Du Cancer | Dicato M.,Laboratoire Of Biologie Moleculaire Et Cellulaire Du Cancer | Diederich M.,Seoul National University
Molecular Nutrition and Food Research | Year: 2013

Epigenetic alterations correspond to changes in DNA methylation, covalent modifications of histones, or altered miRNA expression patterns. These three mechanisms are interconnected and appear to be key players in tumor progression and failure of conventional chemotherapy. Dietary components emerged as a promising source of new epigenetically active compounds able to reverse these alterations and to actively regulate gene expression as well as molecular targets implicated in tumorigenesis. The polyphenolic compound curcumin (diferuloylmethane), a yellow spice that enters into the composition of curry, already described for its diverse and broad biological activities, is nowadays well described as an inhibitor of DNA methyltransferase so that it is considered as a DNA hypomethylating agent. It reestablishes the balance between histone acetyl transferase and histone deacetylase (HDAC 1, 3, 4, 5, 8) activity to selectively activate or inactivate the expression of genes implicated in cancer death and progression, respectively. Finally curcumin modulates miRNAs (miR-15a, miR-16, miR-21, miR-22, miR-26, miR-101, miR-146, miR-200, miR-203, and let-7) and their multiple target genes. In conclusion, this dietary compound is able to restore the epigenetic regulation balance and appears as an attractive preventive and/or therapeutic approach against human cancer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cho Y.M.,University of British Columbia | Cho Y.M.,Seoul National University | Merchant C.E.,University of British Columbia | Kieffer T.J.,University of British Columbia
Pharmacology and Therapeutics | Year: 2012

Diabetes is a debilitating disease characterized by chronic hyperglycemia and is often associated with obesity. With diabetes and obesity incidence on the rise, it is imperative to develop novel therapeutics that will not only lower blood glucose levels, but also combat the associated obesity. The G protein-coupled receptors (GPCRs) for glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1) and glucagon are emerging as targets to treat both hyperglycemia and obesity. GIP is rapidly released from intestinal K-cells following food intake and stimulates glucose-dependent insulin secretion from β-cells and the storage of fat in adipocytes. Both GIP receptor agonists and antagonists have been demonstrated to display therapeutic potential to treat diabetes and obesity. Similar to GIP, GLP-1 is released from intestinal L-cells following food intake and potentiates glucose-dependent insulin secretion from β-cells. In addition, GLP-1 reduces glucagon levels, suppresses gastric emptying and reduces food intake. As such, GLP-1 receptor agonists effectively lower blood glucose levels and reduce weight. Finally, glucagon is released from α-cells and raises blood glucose levels during the fasting state by stimulating gluconeogenesis and glycogenolysis in the liver. Thus, molecules that antagonize the glucagon receptor may be used to treat hyperglycemia. Given the structural similarity of these peptides and their receptors, molecules capable of agonizing or antagonizing combinations of these receptors have recently been suggested as even better therapeutics. Here we review the biology of GIP, GLP-1 and glucagon and examine the various therapeutic strategies to activate and antagonize the receptors of these peptides. © 2012 Elsevier Inc.

Choi H.D.,Dongguk University | Shin W.G.,Seoul National University
Current Medical Research and Opinion | Year: 2014

Background: Dyslipidemia is a major risk factor for cardiovascular disease and is treated with many effective lipid-lowering agents. Statins are often used alone or in combination with fibrates. Combination therapy is more effective due to their comparative actions, but the increased incidence of side effects should be considered carefully. Research design and methods: A meta-analysis of published data was conducted to compare the safety and efficacy of statins alone versus statins plus fibrates in patients with dyslipidemia. In total, nine articles were assessed for efficacy analysis and ten articles were assessed for safety analysis. Results: In the efficacy analysis, a combination of statins and fibrates provided significantly greater reductions in total cholesterol (SE = 0.430; 95% CI 0.315-0.545), LDL cholesterol (SE = 0.438; 95% CI 0.321-0.555) and triglycerides (SE = 0.747; 95% CI 0.618-0.876), and a significantly greater increase in HDL cholesterol (SE = 0.594; 95% CI 0.473-0.715) than treatment with statins alone. In the safety analysis, treatment with statins alone was associated with a significant reduction in the numbers of total adverse events (RR = 0.665; 95% CI 0.539-0.819), liver-related adverse events (RR = 0.396; 95% CI 0.206-0.760) and kidney-related adverse events (RR = 0.146; 95% CI 0.075-0.285). Conclusion: We suggest that treatment with statins plus fibrates provides clinical benefits over treatment with statins alone but increased risks, especially of hepatic or renal side effects, should be monitored carefully. © 2014 Informa UK Ltd.

Kwon H.-J.,Seoul National University | Cho S.-H.,BioPOA Co.
Vaccine | Year: 2011

SG 9R, a rough vaccine strain of Salmonella gallinarum, has been used for the prevention of fowl typhoid and paratyphoid in the world despite the presence of residual virulence. SG 9R-like rough strains have been recently isolated from fowl typhoid cases; however, molecular markers to differentiate SG 9R from field strains are not well-characterized and the molecular mechanisms of SG 9R residual virulence are unclear. Therefore, we analyzed LPS biosynthesis (rfa gene cluster) and virulence genes (spv, SPI-2) of both SG 9R and S. gallinarum rough field strains. SG 9R carried a unique nonsense mutation in rfaJ (TCA to TAA) and a shared rfaZ mutation (G-deletion) by rough and smooth S. gallinarum strains. SG 9R also carried intact SPI-2 and spvC, B, A, and R (except deleted spvD). SG 9R-like rough strains (n = 10) carried identical mutations in virulence-related genes to SG 9R. SG 9R and SG 9R-like rough strains did not demonstrate significant mortality or liver lesions under normal conditions. However, fowl typhoid was successfully reproduced in the present study by SG 9R inoculation to 1-day-old male brown layer chicks per os following starvation. Therefore, the LPS defect may be one of the major mechanisms of SG 9R attenuation, and the possession of intact SPI-2, spvC, B, A, and R virulence genes may be associated with residual SG 9R virulence. © 2010 Elsevier Ltd.

Bang Y.-J.,Seoul National University
Recent Results in Cancer Research | Year: 2012

Survival rates following curative resection for gastric cancer are higher in East Asia than in Europe and the US. The aggressive surgical approach adopted in East Asia may explain these observations. In Japan and Korea, gastrectomy with extended lymphadenectomy (D2 gastrectomy) has been standard of care for many years, whereas gastrectomy with lymphadenectomy of the perigastric lymph nodes (D1 surgery) has been favored in Europe and the US until recently. D2 surgery is now recommended globally based on the 15-year findings from the large Dutch D1D2 study, which showed a reduction in cancer-related deaths with D2 versus D1 surgery. Improved outcomes are now being reported in the US and Europe as D2 surgery becomes more widely used. In addition to surgery, systemic therapy is also required to control recurrences, although the preferred regimen differs by region. Given that some of the studies on which these preferences are based predate the widespread acceptance of D2 surgery, the optimal regimen should be considered carefully. Recent studies from East Asia support the use of adjuvant chemotherapy after D2 surgery. Adjuvant chemotherapy should also be considered a valid approach in other regions now that the benefits of D2 surgery have been demonstrated unequivocally. © 2012 Springer-Verlag Berlin Heidelberg.

Kim S.,Seoul National University | You S.,Pohang University of Science and Technology | Hwang D.,Pohang University of Science and Technology
Nature Reviews Cancer | Year: 2011

Over the past decade, the identification of cancer-associated factors has been a subject of primary interest not only for understanding the basic mechanisms of tumorigenesis but also for discovering the associated therapeutic targets. However, aminoacyl-tRNA synthetases (ARSs) have been overlooked, mostly because many assumed that they were simply 'housekeepers' that were involved in protein synthesis. Mammalian ARSs have evolved many additional domains that are not necessarily linked to their catalytic activities. With these domains, they interact with diverse regulatory factors. In addition, the expression of some ARSs is dynamically changed depending on various cellular types and stresses. This Analysis article addresses the potential pathophysiological implications of ARSs in tumorigenesis. © 2011 Macmillan Publishers Limited. All rights reserved.

Kim J.W.,Seoul National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2013

This study compared the clinical outcomes between endoscopic and radiologic placement of self-expandable metal stent (SEMS) in patients with malignant colorectal obstruction. In total, 111 patients were retrospectively enrolled in this study between January 2003 and June 2011 at Seoul National University Boramae Hospital. Technical and clinical success rates, complication rates, and stent patency were compared between using an endoscopic (n=73) or radiologic (n=38) method during the SEMS placement procedure. The technical success rate was higher in the endoscopic method than in the radiologic method (100% [73/73] vs. 92.1% [35/38], respectively; p=0.038). In addition, in 3 of the remaining 35 patients in the radiologic-method group, adjuvant endoscopic assistance was required. In the six patients (including the three aforementioned patients), the causes of technical failure were the inability to pass the guidewire into an obstructive lesion due to a tortuous, curved angulation of the sigmoid or descending colon (n=4), and a difficult approach to a lesion located at the descending or transverse colon (n=2). The clinical success rate, complication rate, and stent patency did not differ significantly between the two methods (p=0.424, 0.303, and 0.423, respectively). When the colorectal obstruction had a tortuous, curved angulation of the colon or was located at or proximal to the descending colon, the endoscopic method of SEMS placement appears to be more useful than the radiologic method. However, once SEMS placement was technically successful, the clinical success rate, complication rate, and stent patency did not differ with the method of insertion.

Pak S.,Seoul National University
Economics and Human Biology | Year: 2010

This paper is a study of the growth status of 1406 North Korean refugee children and adolescents who were between 6 and 19.9 years of age at the time of their arrival in South Korea, during the years 1995-2007, as compared with that of their South Korean peers. Refugee children of 6.5 years of age were found to be taller and heavier than North Korean children of the same age residing in North Korea. On the other hand, all of the North Korean refugee boys and girls were shorter and weighed less than their South Korean peers. This disparity in height and weight growth status was smallest during the pre-teen years and then began to increase, peaking in the mid-teen years and decreasing in the late-teen years, with the late-teen disparity being still larger than the pre-teen one. This pattern of disparity suggests that the greatest gap observed in mid-teen years was caused by differences in growth tempos during the period of pubertal growth and that the final differences in body size between the North and South Korean adults were partly pubertal in origin. The mean height-for-age z-score (HAZ) and weight-for-age z-score (WAZ) of the North Korean refugee boys were significantly lower than those of the North Korean refugee girls, indicating that the girls' growth status was better than that of the boys. In addition, the WAZ of the North Korean refugee children and adolescents was higher than their HAZ, indicating that their growth in height is poorer than that of weight. A regression analysis revealed that the mean HAZ of North Korean refugee children and adolescents born between 1995 and 1999, a period during which North Korea suffered a famine, was not statistically significantly lower than that of those born earlier. The time that the North Korean children and adolescents spent outside of North Korea before entering South Korea was discovered to have had a positive effect on their growth status, suggesting that they experienced some degree of catch-up growth while staying in transit countries. Among all the available socio-demographic variables, only four - sex, age at escape and measurement, time interval between escape from North Korea and arrival in South Korea, and year of escape - were found to be significant factors in their growth status. © 2010 Elsevier B.V.

AtMYB44 is a member of the R2R3 MYB subgroup 22 transcription factors and regulates diverse cellular responses in Arabidopsis thaliana. We performed quadruple 9-merbased protein binding microarray (PBM) analysis, which revealed that full-size AtMYB44 recognized and bound to the consensus sequence AACnG, where n represents A, G, C or T. The consensus sequence was confirmed by electrophoretic mobility shift assay (EMSA) with a truncated AtMYB44 protein containing the N-terminal side R2R3 domain. This result indicates that the R2R3 domain alone is sufficient to exhibit AtMYB44 binding specificity. The sequence AACnG is the type I binding site for MYB transcription factors, including all members of the subgroup 22. EMSA showed that the R2R3 domain protein binds in vitro to promoters of randomly selected Arabidopsis genes that contain the consensus binding sequence. This implies that AtMYB44 binds to any promoter region that contains the consensus sequence, without determining their functional activity or specificity. The C-terminal side transcriptional activation domain of AtMYB44 contains an asparagine-rich fragment, NINNTTSSRHNHNN (aa 215-228), which, among the members of subgroup 22, is unique to AtMYB44. A transcriptional activation assay in yeast showed that this fragment is included in a region (aa 200-240) critical for the ability of AtMYB44 to function as a transcriptional activator. We hypothesize that the C-terminal side of the protein, but not the N-terminal side of the R2R3 domain, contributes to the functional activity and specificity of AtMYB44 through interactions with other regulators generated by each of a variety of stimuli.

The recent outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) infections in South Korea in May 2015 revealed that the Korean healthcare system and hospitals are highly vulnerable to hospital-spread infections. In a short period of time, MERS-CoV infection spread widely across Korea due to the unique characteristics of the Korean healthcare system including 1) hospitals with limited infection control capabilities, 2) a heavy dependency on private caregivers due to a nursing shortage, 3) emergency department overcrowding, and 4) healthcare-related patient behaviour such as hospital shopping. To prevent future outbreaks of emerging infectious diseases similar to MERS-CoV, the Korean healthcare system should be reformed and healthcare-related patient behaviour must change. To improve the performance of hospital infection control, the National Health Insurance service should pay more for hospital infection control services and cover private patient rooms when medically necessary, including for infectious disease patients. To reduce risks of hospital infection related to private caregiving, the nurse staffing level should be increased and hospitals should take full responsibility for inpatient nursing care. To reduce hospital shopping, the National Health Insurance service should introduce a differential fee schedule which pays more when primary care providers care for patients with common conditions and tertiary care providers care for patients with severe conditions. To incentivize patients for appropriate health care use, lower patient out-of-pocket payments should be combined with a differential provider fee schedule. © Korean Medical Association.

Shin D.,Seoul National University
Journal of Physical Chemistry C | Year: 2016

In SERS (surface enhanced Raman spectroscopy), platinum metal has been regarded as a relatively poor Raman enhancing substrate material compared to other coinage metals such as gold, silver, or copper, even though it has plenteous advantages in various catalyst or energy applications. Thanks to the recent realization of fabricating large-sized platinum nanoparticles, which have a higher extinction in the visible region, it became realized that the platinum nanoparticles can induce the surface enhanced Raman scattering signal on various macroscopically smooth novel metal substrates, such as gold and silver, with visible excitation. However, an all platinum made with reliable SERS enhancing structure has not been realized until now. Here, further, large-sized platinum nanoparticles can also induce SERS signal even at a smooth platinum substrate with use of the bifunctional linker molecule 1,4-phenylenediisocyanide (1,4-PDI). This all platinum made gap mode nanostructure exhibits the apparent SERS signal of 1,4-PDI, and its enhancement factor was compared experimentally with that of a silver nanoparticle-planar platinum or gold nanoparticle-planar platinum structure along with wavelength-dependent experiments. This result provides a deeper understanding of the recently attracted gap mode structure in SERS, and it has the potential to be utilized as a model structure for monitoring various platinum-based catalytic processes via Raman spectroscopy. © 2016 American Chemical Society.

Kim J.,Seoul National University
Journal of Medical Internet Research | Year: 2014

Background: The recent increase in chronic diseases and an aging population warrant the necessity of health self-management. As small electronic devices that track one's activity, sleep, and diet, called self-trackers, are being widely distributed, it is prudent to investigate the user experience and the effectiveness of these devices, and use the information toward engineering better devices that would result in increased efficiency and usability. Objective: The aim of this study was to abstract the constructs that constitute the user experiences of the self-tracker for activity, sleep, and diet. Additionally, we aimed to develop and verify the Health Information Technology Acceptance Model-II (HITAM-II) through a qualitative data analysis approach. Methods: The study group consisted of 18 female college students who participated in an in-depth interview after completing a 3-month study of utilizing a self-tracker designed to monitor activity, sleep, and diet. The steps followed in the analysis were: (1) extraction of constructs from theoretical frameworks, (2) extraction of constructs from interview data using a qualitative methodology, and (3) abstraction of constructs and modeling of the HITAM-II. Results: The constructs that constitute the HITAM-II are information technology factors, personal factors, social factors, attitude, behavioral intention, and behavior. These constructs are further divided into subconstructs to additionally support the HITAM-II. Conclusions: The HITAM-II was found to successfully describe the health consumer's attitude, behavioral intention, and behavior from another perspective. The result serves as the basis for a unique understanding of the user experiences of HIT. © Holly O Witteman.

Functional annotations are available only for a very small fraction of microRNAs (miRNAs) and very few miRNA target genes are experimentally validated. Therefore, functional analysis of miRNA clusters has typically relied on computational target gene prediction followed by Gene Ontology and/or pathway analysis. These previous methods share the limitation that they do not consider the many-to-many-to-many tri-partite network topology between miRNAs, target genes, and functional annotations. Moreover, the highly false-positive nature of sequence-based target prediction algorithms causes propagation of annotation errors throughout the tri-partite network. A new conceptual framework is proposed for functional analysis of miRNA clusters, which extends the conventional target gene-centric approaches to a more generalized tri-partite space. Under this framework, we construct miRNA-, target link-, and target gene-centric computational measures incorporating the whole tri-partite network topology. Each of these methods and all their possible combinations are evaluated on publicly available miRNA clusters and with a wide range of variations for miRNA-target gene relations. We find that the miRNA-centric measures outperform others in terms of the average specificity and functional homogeneity of the GO terms significantly enriched for each miRNA cluster. We propose novel miRNA-centric functional enrichment measures in a conceptual framework that connects the spaces of miRNAs, genes, and GO terms in a unified way. Our comprehensive evaluation result demonstrates that functional enrichment analysis of co-expressed and differentially expressed miRNA clusters can substantially benefit from the proposed miRNA-centric approaches.

Kang S.-M.,Kyungpook National University | Lee H.-J.,Seoul National University
Cancer Letters | Year: 2013

MicroRNAs constitute a class of small noncoding RNAs that play roles in tumorigenesis. We found that NKX2-1 protein levels were generally high in the lung cancer tissues whereas miRNA-365 expression levels were downregulated. Ectopic miR-365 expression decreased NKX2-1 expression in lung cancer cell lines. Transfection of a miR-365 mimic led to reduced proliferation of lung cancer cells; conversely, a miR-365 inhibitor slightly increased cell proliferation. The NKX2-1 overexpression significantly increased the cell proliferation by overcoming the suppressive effect of miR-365. Our data suggest that miR-365 is an important regulator of NKX2-1 and can be a target for lung cancer therapies. © 2013 Elsevier Ireland Ltd.

Chae J.,Seoul National University
Astrophysical Journal | Year: 2014

We propose a generalization of Becker's cloud model (BCM): an embedded cloud model (ECM) - for the inversion of the core of the Hα line spectrum of a plasma feature either lying high above the forest of chromospheric features or partly embedded in the outermost part of this forest. The fundamental assumption of the ECM is that the background light incident on the bottom of the feature from below is equal to the ensemble-average light at the same height. This light is related to the observed ensemble-average light via the radiative transfer that is described by the four parameters newly introduced in addition to the original four parameters of the BCM. Three of these new parameters are independently determined from the observed rms contrast profile of the ensemble. We use the constrained χ2 fitting technique to determine the five free parameters. We find that the ECM leads to the fairly good fitting of the observed line profiles and the reasonable inference of physical parameters in quiet regions where the BCM cannot. Our first application of this model to a quiet region of the Sun indicates that the model can produce the complete velocity map and Doppler width map of the region. © 2014. The American Astronomical Society. All rights reserved..

Muthaiah S.,Nanyang Technological University | Hong S.H.,Seoul National University
Advanced Synthesis and Catalysis | Year: 2012

An efficient, operatively simple, acceptorless, and base-free dehydrogenation of secondary alcohols and nitrogen-containing heterocyclic compounds was achieved by using readily available ruthenium hydride complexes as precatalysts. The complex RuH 2(CO)(PPh 3) 3 (1) and Shvo's complex (2) showed excellent activities for the dehydrogenation of secondary alcohols and nitrogen containing heterocycles. In addition to complexes 1 and 2, the complex RuH 2(PPh 3) 4 (3) also showed moderate to excellent activity for the acceptorless dehydrogenation of nitrogen-containing heterocyclic compounds. Kinetic studies on the oxidation reaction of 1-phenylethanol using complex 1 were carried out in the presence and the absence of external triphenylphosphine (PPh 3). External addition of PPh 3 had a negative influence on the rate of the reaction, which suggested that dissociation of PPh 3 occurred during the course of the reaction. Hydrogen was evolved from the oxidation reaction of 1-phenylethanol by using 1 mol% of 1 (88%) and 2 (92%), which demonstrated the possible usage of the catalytic systems in hydrogen generation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bang Y.-J.,Seoul National University
Archives of Pathology and Laboratory Medicine | Year: 2012

Crizotinib (Xalkori), the first inhibitor of both anaplastic lymphoma kinase (ALK) and c-Met receptor kinases, has been approved in the United States, Korea, and other countries for the treatment of ALK-positive non-small cell lung cancer (NSCLC). This approval came within just 4 years of the discovery of rearrangements in the ALK gene in a subset of patients with NSCLC. Oral crizotinib 250 mg twice daily showed excellent efficacy in patients with advanced ALK-positive NSCLC, with objective response rates of 61% and 51% in ongoing phase I and II studies, respectively. Objective response rates of current standard, single-agent, second-line therapies are less than 10%. Median progression-free survival was 10 months (95% confidence interval, 8.2-14.7) in the phase I study expanded cohort and has yet to be reached in the phase II study; progression-free survival with current therapies is less than 3 months. Crizotinib was well tolerated; grade 1/2 gastrointestinal toxicity and visual disturbances were the most common adverse events. Patients in the phase II study reported improvements in fatigue, dyspnea, and cough, based on quality of life assessments. Phase III studies investigating crizotinib for the first- and secondline treatment of advanced ALK-positive NSCLC, versus current standards of care, are ongoing. Crizotinib represents a new standard of care for patients with ALK-positive NSCLC and highlights the importance of the role of the pathologist, as molecular profiling becomes a part of initial workups for newly diagnosed patients with NSCLC. This approach will ensure effective individualized treatment for patients with NSCLC. Copyright © 2012 College of American Pathologists.

Cho S.-H.,Seoul National University
Allergy, Asthma and Immunology Research | Year: 2010

Major classes of medication in asthma management include bronchodilating β2-agonists, anti-inflammatory inhaled corticosteroids, leukotriene modifiers and theophyllines. However, all asthmatics do not respond to the same extent to a given medication. Available data suggest that a substantial range of individual variability, as much as 70%, may be due to genetic characteristics of each patient. Pharmacogenomics offers the potential to optimize medications for individual asthmatics by using genetic information to improve efficacy or avoid adverse effects. The best-studied case of the potential contribution of pharmacogenomics to treatment response in asthma comes from studies on human β2 adrenergic receptors. In addition, genetic variation in β2-adrenergic receptor (Arg16Gly) may predict response to anticholinergics for the treatment of asthma. In case of inhaled corticosteroids, a recent investigation using a traditional SNP-based approach identified a gene for corticotropin releasing hormone receptor 1 as a potential marker of response. Another major pathway that has been investigated is the pathway underlying response to cysteinyl leukotriene receptor antagonist. It is likely that in the near future, pharmacogenomic approaches based on individual genetic information will be introduced into an asthma treatment guideline and this guideline will allow us to identify those who have the best chance to respond to a specific medication. © Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology.

Min K.-B.,Ajou University | Min J.-Y.,Seoul National University
Cancer Science | Year: 2014

Lung cancer is one of the most common cancers worldwide and is the leading cause of cancer-induced death in the USA. Although much attention has been focused on the anti-carcinogenic effect of consuming carotenoid-containing food or supplements, the results have been inconsistent. We investigated whether serum carotenoid levels were associated with the mortality risk of lung cancer in US adults using data from a nationally representative sample. The data were obtained from the Third Nutrition and Health Examination Survey (NHANES III) database and the NHANES III Linked Mortality File. A total of 10 382 participants aged over 20 years with available serum carotenoid levels and no other missing information on questionnaires and biomarkers at baseline (NHANES III) were included in the present study. Of the 10 382 participants, 161 subjects died due to lung cancer. We found that high serum levels of alpha-carotene and beta-cryptoxanthin at baseline were significantly associated with a lower risk of lung cancer death. When we stratified the risk by current smoking status, the risk of death of current smokers was significantly decreased to 46% (95% confidence interval, 31-94%) for alpha-carotene and 61% (95% confidence interval, 19-80%) for beta-cryptoxanthin. By contrast, no association was observed among never/former smokers at baseline. High serum levels of alpha-carotene and beta-cryptoxanthin are associated with a lower risk of lung cancer death in US adults. High serum levels of alpha-carotene and beta-cryptoxanthin at baseline were significantly associated with a lower risk of lung cancer mortality after adjustment for potential covariates.The mortality risk of current smokers was significantly decreased to 46% (95% CI, 0.31-0.94) for alpha-carotene and 61% (95% CI, 0.19-0.80) for beta-cryptoxanthin, respectively. By contrast, no association was observed among never/former smokers at baseline. © 2014 The Authors.

Cheong Y.W.,Gyeonggi Science High School | Lee S.-W.,Seoul National University
Physical Review Letters | Year: 2012

We derive a tight bound between the quality of estimating a quantum state by measurement and the success probability of undoing the measurement in arbitrary dimensional systems, which completely describes the tradeoff relation between the information gain and reversibility. In this formulation, it is clearly shown that the information extracted from a weak measurement is erased through the reversing process. Our result broadens the information-theoretic perspective on quantum measurement as well as provides a standard tool to characterize weak measurements and reversals. © 2012 American Physical Society.

Lee S.W.,Seoul National University
The EMBO journal | Year: 2012

Heterogeneous ribonucleoprotein-K (hnRNP-K) is normally ubiquitinated by HDM2 for proteasome-mediated degradation. Under DNA-damage conditions, hnRNP-K is transiently stabilized and serves as a transcriptional co-activator of p53 for cell-cycle arrest. However, how the stability and function of hnRNP-K is regulated remained unknown. Here, we demonstrated that UV-induced SUMOylation of hnRNP-K prevents its ubiquitination for stabilization. Using SUMOylation-defective mutant and purified SUMOylated hnRNP-K, SUMOylation was shown to reduce hnRNP-K's affinity to HDM2 with an increase in that to p53 for p21-mediated cell-cycle arrest. PIAS3 served as a small ubiquitin-related modifier (SUMO) E3 ligase for hnRNP-K in an ATR-dependent manner. During later periods after UV exposure, however, SENP2 removed SUMO from hnRNP-K for its destabilization and in turn for release from cell-cycle arrest. Consistent with the rise-and-fall of both SUMOylation and stability of hnRNP-K, its ability to interact with PIAS3 was inversely correlated to that with SENP2 during the time course after UV exposure. These findings indicate that SUMO modification plays a crucial role in the control of hnRNP-K's function as a p53 co-activator in response to DNA damage by UV.

Ahn S.-J.,Chonnam National University | Nam S.-R.,Myongji University | Choi J.-H.,Chonnam National University | Moon S.-I.,Seoul National University
IEEE Transactions on Smart Grid | Year: 2013

This paper is concerned with the power dispatch problem of distributed generators (DGs) for optimal operation of a microgrid. The objective is to minimize the fuel cost during the grid-connected operation, while ensuring stable operation after islanding. To achieve this goal, the economic dispatch (ED) problem and related constraints are formulated. The constraints considered in this study are: i) reserve for variation in load demand, ii) reserve for variation in the power outputs of non-dispatchable DGs, iii) flow limits between two adjacent areas, and iv) reserve for the stable islanded operation. The first three constraints, which have been employed in ED problem for conventional power systems, are modified to apply to Microgrids. We also provide a detailed formulation of the constraint for stable islanded operation in accordance with two power-sharing principles: i) fixed droop and ii) adjustable droop. The problem is solved using a modified direct search method, and the effect of the constraints on the operational cost is investigated via numerical simulations. © 2012 IEEE.

Ryu S.,Seoul National University
Nuclear Physics B - Proceedings Supplements | Year: 2014

We report a study of τ lepton decays involving K0S with a 669 fb-1 data sample accumulated with the Belle detector at the KEKB asymmetric-energy e+ e- collider. The branching fractions have been measured for the τ- → π-K0Sντ, K-K0Sντ, π-K0Sπ0ντ, K-K0Sπ0ντ, π-K0Sπ0 ντ and π-K0SK0Sπ0ντ decays. We also provide the unfolded mass spectra for τ- → π-K0Sπ0ντ and τ- → K-K0Sπ0ντ. © 2014 Elsevier B.V.

Yang H.R.,Seoul National University
Korean Journal of Pediatrics | Year: 2013

Because nonalcoholic steatohepatitis can progress towards cirrhosis even in children, early detection of hepatic fibrosis and accurate diagnosis of nonalcoholic fatty liver disease (NAFLD) are important. Although liver biopsy is regarded as the gold standard of diagnosis, its clinical application is somewhat limited in children due to its invasiveness. Noninvasive diagnostic methods, the spectrum of NAFLD, particularly the severity of hepatic fibrosis. Although data and validation are still lacking for these noninvasive modalities in the pediatric population, these methods including imaging studies, biomarkers of inflammation, oxidative stress, hepatic apoptosis, hepatic fibrosis, and noninvasive hepatic fibrosis scores have recently been developed for diagnosing may be applicable for pediatric NAFLD. Therefore, noninvasive imaging studies, biomarkers, and hepatic fibrosis scoring systems may be useful in the detection of hepatic steatosis and the prediction of hepatic fibrosis, even in children with NAFLD. © 2013 by The Korean Pediatric Society.

Jo Y.S.,University of Washington | Lee I.,Seoul National University
Journal of Neuroscience | Year: 2010

The hippocampus and the perirhinal cortex (PR) are reciprocally connected both directly and indirectly via the entorhinal cortex. Although it has been hypothesized that the two regions should have intimate functional interactions with each other on the basis of the anatomical connectivity, many lesion studies have demonstrated functional dissociations instead between the hippocampus and PR. To show a tight functional relationship between the two regions, we used reversible inactivation techniques targeting both the hippocampus and PR within subjects, combined with a biconditional memory task in which the rat must consider information about objects and their locations. Specifically, rats were implanted with two sets of bilateral cannulas into the hippocampus and PR, and were tested in an object-place paired-associate task in a radial maze. While alternating between two arms, the rats were required to choose one of the objects exclusively associated with a given arm for food. Bilateral muscimol (MUS) injections into either the hippocampus or PR equally produced chance level performance. When a functional disconnection procedure was used to disrupt the interaction between the hippocampus and PR, contralateral MUS injections into the hippocampus and PR resulted in severe impairment in performance. However, inactivating the hippocampus and PR ipsilaterally did not affect the performance. In a simple object discrimination task, the same functional disconnection protocol with MUS did not affect the performance. The results powerfully demonstrate that the hippocampus, the PR, and their functional interactions are all indispensable when objects and their spatial locations must be processed at the same time. Copyright © 2010 the authors.

Lee S.-H.,Seoul National University
Neurology | Year: 2010

Background: Although the critical role of alkaline phosphatase in bone mineralization is clearly understood, the potentially adverse effect of high alkaline phosphatase levels on the cardiovascular system was only recently suggested. In this study, we hypothesized that increased levels of serum alkaline phosphatase may be associated with poor outcome after stroke in terms of mortality. Methods: We prospectively included patients with acute stroke admitted consecutively to our hospital, from October 2002 to September 2008. A total of 2,029 patients were selected for the analyses. In the analyses of mortality, the patients were divided by baseline measurements into quintiles of alkaline phosphatase levels (<57, 57-69, 70-81, 82-97, >97 IU/L). Results: In the Cox proportional hazard models, compared with the first alkaline phosphatase quintile, adjusted hazard ratios of the third, fourth, and fifth quintiles for all-cause death were 1.67 (95% confidence interval 1.12-2.49), 1.79 (1.20-2.67), and 2.83 (1.95-4.10). When we divided the patients into ischemic and hemorrhagic stroke, the association was also significant for both subtypes of stroke. In terms of vascular death, compared to the first alkaline phosphatase quintile, the adjusted hazard ratios of the fourth and fifth quintiles of alkaline phosphatase were 1.81 (95% confidence interval 1.14-2.86) and 2.78 (1.87-4.15). Conclusion: Our study demonstrated that increased serum levels of alkaline phosphatase are an independent predictor of all-cause and vascular death after either ischemic or hemorrhagic stroke. Copyright © 2010 by AAN Enterprises, Inc.

Insulin resistance (IR) is believed to be the underlying mechanism of metabolic syndrome and type 2 diabetes mellitus (DM). Recently, a few studies have demonstrated that phthalates could cause oxidative stress which would contribute to the development of IR. Therefore, we evaluated whether exposure to phthalates affects IR, and oxidative stress is involved in the phthalates-IR pathway. We recruited 560 elderly participants, and obtained blood and urine samples during repeated medical examinations. For the determination of phthalate exposure, we measured urinary levels of mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) as metabolites of diethylhexyl phthalates (DEHP), and mono-n-butyl phthalate (MnBP) as a metabolite of di-butyl phthalate (DBP). Malondialdehyde (MDA), an oxidative stress biomarker, was also measured in urine samples. We measured serum levels of fasting glucose and insulin, and derived the homeostatic model assessment (HOMA) index to assess IR. A mixed-effect model and penalized regression spline were used to estimate the associations among phthalate metabolites, MDA, and IR. The molar sum of MEHHP and MEOHP (∑DEHP) were significantly associated with HOMA (β = 0.26, P = 0.040), and the association was apparent among participants with a history of DM (β = 0.88, P = 0.037) and among females (β = 0.30, P = 0.022). However, the relation between MnBP and HOMA was not found. When we evaluated whether oxidative stress is involved in increases of HOMA by ∑DEHP, MDA levels were significantly associated with increases of ∑DEHP (β = 0.11, P<0.001) and HOMA (β = 0.49, P = 0.049). Our study results suggest that exposure to DEHP in the elderly population increases IR, which is related with oxidative stress, and that participants with a history of DM and females are more susceptible to DEHP exposure.

Ping Z.,Seoul National University
Neurocomputing | Year: 2013

The spherical inverted pendulum is a fairly complex nonlinear system with two inputs, two outputs, eight states and an unstable zero dynamics. Recently, some attempts have been made to study the output regulation problem of this system subject to a neutrally stable exosystem. The existing approaches have made use of the approximate solution of the regulator equations based on polynomial method or neural network method. However, since the regulator equations of the system are governed by ten nonlinear partial differential and algebraic equations, it is quite tedious to obtain the approximate solution of the regulator equations. In this paper, a scheme based on neural network approximation of the feedforward function without solving the regulator equations approximately will be adopted. Since the dimension of the feedforward function is only equal to two, this new scheme is much simpler than the existing approaches. Moreover, when all the states are available, our design offers certain robustness to plant parameter variations and leads to good tracking performance. © 2012 Elsevier B.V.

Kang H.J.,Seoul National University | Loftus S.,Merck And Co. | Taylor A.,Merck And Co. | DiCristina C.,Merck And Co. | And 2 more authors.
The Lancet Oncology | Year: 2015

Background: Oral aprepitant, a neurokinin-1 receptor antagonist, is recommended in combination with other anti-emetic agents for the prevention of nausea and vomiting associated with moderately or highly emetogenic chemotherapy in adults, but its efficacy and safety in paediatric patients are unknown. We did this phase 3 trial to examine the safety and efficacy of such treatment in children. Methods: In this final analysis of a phase 3, randomised, multicentre, double-blind study, patients aged 6 months to 17 years with a documented malignancy who were scheduled to receive either moderately or highly emetogenic chemotherapy were randomly assigned with an interactive voice response system to an age-based and weight-based blinded regimen of aprepitant (125 mg for ages 12-17 years; 3.0 mg/kg up to 125 mg for ages 6 months to <12 years) plus ondansetron on day 1, followed by aprepitant (80 mg for ages 12-17 years; 2.0 mg/kg up to 80 mg for ages 6 months to <12 years) on days 2 and 3, or placebo plus ondansetron on day 1 followed by placebo on days 2 and 3; addition of dexamethasone was allowed. Randomisation was stratified according to patient age, planned use of chemotherapy associated with very high risk of emetogenicity, and planned use of dexamethasone as an anti-emetic. Ondansetron was dosed per the product label for paediatric use or local standard of care. The primary efficacy endpoint was the proportion of patients who achieved complete response (defined as no vomiting, no retching, and no use of rescue medication) during the 25-120 h (delayed phase) after initiation of emetogenic chemotherapy. Efficacy and safety analyses were done with all randomly assigned patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, number NCT01362530. Findings: Between Sept 22, 2011, and Aug 16, 2013, 307 patients were randomly assigned at 49 sites in 24 countries to either the aprepitant group (155 patients) or to the control group (152 patients). Three patients in the aprepitant group and two in the control group did not receive study medication, and thus were excluded from analyses. 77 (51%) of 152 patients in the aprepitant group and 39 (26%) of 150 in the control group achieved a complete response in the delayed phase (p<0.0001). The most common grade 3-4 adverse events were febrile neutropenia (23 [15%] of 152 in the aprepitant group vs 21 [14%] of 150 in the control group), anaemia (14 [9%] vs 26 [17%]), and decreased neutrophil count (11 [7%] vs 17 [11%]). The most common serious adverse event was febrile neutropenia (23 [15%] patients in the aprepitant group vs 22 [15%] in the control group). Interpretation: Addition of aprepitant to ondansetron with or without dexamethasone is effective for the prevention of chemotherapy-induced nausea and vomiting in paediatric patients being treated with moderately or highly emetogenic chemotherapy. © 2015 Elsevier Ltd.

PURPOSE: This study aimed to determine whether an iterative model–based reconstruction (IMR) can improve lesion conspicuity and depiction on computed tomography (CT) compared with filtered back projection (FBP) and hybrid iterative reconstruction (iDose) using anthropomorphic phantoms.MATERIALS AND METHODS: One small and one large anthropomorphic body phantoms, each containing 8 simulated focal liver lesions (FLLs), were scanned using a 256-channel CT scanner at 120 kVp with variable tube current-time products (10-200 mAs). Scans were divided into 3 groups based on radiation dose (RD) as follows: (a) full dose (FD), (b) low dose (FD50), and (c) ultralow dose (FD25 for the large phantom, FD15 for the small phantom). All images were reconstructed using FBP, iDose, and IMR. Image noise and lesion-to-liver contrast were assessed quantitatively and qualitatively. Thereafter, 6 radiologists independently evaluated conspicuity of FLLs, and then, compared the number of invisible FLLs on 3 image sets of each RD group.RESULTS: Image noise was significantly lower with IMR than with FBP and iDose at the same RD. Iterative model–based reconstruction improved conspicuity of low-contrast FLLs in all RD groups compared to the others (P < 0.001). Furthermore, compared to FBP and iDose, the number of visible FLLs significantly increased on IMR images in the FD15 group of the small phantom 52.8% [38/72], 68.1% [49/72], and 84.8% [61/72], respectively; P < 0.001) and in the FD 25, FD50 groups of the large phantom (FD50: 56.9% [41/72], 76.4% [55/72], and 84.7% [61/72], respectively; P < 0.05).CONCLUSIONS: Iterative model–based reconstruction reduced image noise and improved low-contrast FLL conspicuity, compared to FBP and iDose. Therefore, depiction of low-contrast FLLs on FBP could be improved using IMR. © 2014 by Lippincott Williams & Wilkins

Bang Y.-J.,Seoul National University
Expert Review of Anticancer Therapy | Year: 2011

Chemotherapy is an important part of treatment for patients with gastric cancer. Although there is no single globally accepted standard of care for patients with advanced disease, regimens typically include a fluoropyrimidine and a platinum compound with or without a third drug (usually epirubicin or docetaxel). Oral fluoropyrimidines, such as capecitabine, offer clear advantages to patients in terms of convenience, but it is only recently that comprehensive data on their efficacy and safety in patients with gastric cancer have become available. The present article reviews capecitabine in the treatment of advanced and resectable gastric cancer. Ongoing Phase III trials involving capecitabine are also discussed. The data show that capecitabine is now established as an integral part of the multi-agent regimens used in the management of patients with gastric cancers. © 2011 Expert Reviews Ltd.

Kang I.-S.,Seoul National University | Kim H.-M.,Georgia Institute of Technology
Journal of Climate | Year: 2010

The predictability of intraseasonal variation in the tropics is assessed in the present study by using various statistical and dynamical models with rigorous and fair measurements. For a fair comparison, the real-time multivariate Madden-Julian oscillation (MJO) (RMM) index, proposed by Wheeler and Hendon, is used as a predictand for all models. The statistical models include the models based on a multilinear regression, a wavelet analysis, and a singular spectrum analysis (SSA). The prediction limits (correlation skill of 0.5) of statistical models for RMM1 (RMM2) index are at days 16-17 (14-15) for the multiregression model, whereas they are at days 8-10 (9-12) for the wavelet- and SSA-based models. The poor predictability of the wavelet and SSA models is related to the tapering problem for a half-length of the time window before the initial condition. To assess the dynamical predictability, long-term serial prediction experiments with a prediction interval of every 5 days are carried out with Seoul National University (SNU) AGCM and coupled general circulation model (CGCM) for 26 (1980-2005) boreal winters. The prediction limits of RMM1 and RMM2 occur at around 20 days for both AGCM and CGCM. These results demonstrate that the skills of dynamical models used in this study are better than those of the three statistical predictions. The dynamical and statistical predictions are combined using a multimodel ensemble method. The combination provides a superior skill to any of the statistical and dynamical predictions, with a prediction limit of 22-24 days. The dependencies of prediction skill on the initial phase and amplitude of the MJO are also investigated. © 2010 American Meteorological Society.

Podoshvedov S.A.,Seoul National University
Journal of Experimental and Theoretical Physics | Year: 2012

We study the method of generation of states that approximate superpositions of large-amplitude coherent states (SCSs) with high fidelity in free-traveling fields. Our approach is based on the representation of an arbitrary single-mode pure state, and SCSs in particular, in terms of displaced number states with an arbitrary displacement amplitude. The proposed optical scheme is based on alternation of photon additions and displacement operators (in the general case, N photon additions and N - 1 displacements are required) with a seed coherent state to generate both even and odd displaced squeezed SCSs regardless of the parity of the used photon additions. It is shown that the optical scheme studied is sensitive to the seed coherent state if the other parameters are unchanged. Output states can approximate either even squeezed SCS or odd SCS shifted relative to each other by some value. This allows constructing a local rotation operator, in particular, the Hadamard gate, which is a mainframe element for quantum computation with coherent states. We also show that three-photon additions with two intermediate displacement operators are sufficient to generate even displaced squeezed SCS with the amplitude 1.7 and fidelity more than 0.99. The effects deteriorating the quality of output states are considered. © Pleiades Publishing, Inc., 2012.

Kim J.,Seoul National University
Telemedicine journal and e-health : the official journal of the American Telemedicine Association | Year: 2011

The study develops strategies for implementing ubiquitous healthcare (u-health) based on previous experiences of the healthcare professionals. Qualitative content analysis, one of qualitative research methods, was used on in-depth interviews conducted between July 21 and October 4, 2009, with 11 healthcare professionals including medical doctors and community healthcare specialist nurses who have previously provided u-health services. Four primary subjects were addressed: (1) subjective experiences on the usability, (2) the expectations, (3) the business prospects, and (4) the prerequisites for the success of u-health market. Based on the results of this study, desirable u-health services from the perspective of healthcare professionals were proposed.

Kim Y.,Seoul National University | Kwon S.,University of Minnesota
Biometrika | Year: 2012

Nonconvex penalties such as the smoothly clipped absolute deviation or minimax concave penalties have desirable properties such as the oracle property, even when the dimension of the predictive variables is large. However, checking whether a given local minimizer has such properties is not easy since there can be many local minimizers. In this paper, we give sufficient conditions under which a local minimizer is unique, and show that the oracle estimator becomes the unique local minimizer with probability tending to one. © 2012 Biometrika Trust.

Lee H.-S.,Seoul National University
Digestive Diseases | Year: 2011

Extrahepatic metastasis (EHM) of hepatocellular carcinoma (HCC) has recently been paradoxically increasing due to increased survival with effective locoregional therapies. The intrahepatic stage of the tumor is important for determining the risk of an extrahepatic lesion. Almost all patients with intrahepatic stage T 3-4, with or without EHM, die of progressive intrahepatic HCC but not due to EHM; thus, the majority of patients with HCC and EHM need to undergo concurrent treatment for intrahepatic HCC. There is no convincing evidence, to date, that systemic chemotherapy improves overall survival. Sorafenib is the first systemic agent that has demonstrated a significant survival benefit in patients with advanced HCC; however, the modest improvement of 3 months is far from satisfactory. Therefore, most hepatologists still rely on the conventional multidisciplinary approach to treat patients with EHM. The concept of the multidisciplinary treatment is the combination of locoregional therapies for both the intrahepatic HCC and symptomatic EHM when confined to a single organ. Targeted therapy may be considered for patients with advanced intrahepatic HCC and multiple EHM, however the potential efficacy of this approach requires confirmation. The outcome of ongoing clinical trials of the multidisciplinary approach, combining conventional locoregional therapy and targeted systemic therapy, is pending. Copyright © 2011 S. Karger AG, Basel.

Kim W.-J.,Gachon University | Moon S.H.,Seoul National University
Catalysis Today | Year: 2012

This article reviews our previous studies to develop high performance catalysts for acetylene hydrogenation. Ethylene selectivity of Pd catalysts in acetylene hydrogenation was improved by adding Si, metal oxides showing SMSI behavior, and either Ag or Cu as promoters. The promoter effect was further enhanced by maximizing the interactions between Pd and added promoters. Chemical vapor deposition was used for the addition of Si, high-temperature reduction for the SMSI metal oxides, and a surface redox (SR) for Ag and Cu. Si modified the Pd surface geometrically, SMSI metal oxides modified Pd both electronically and geometrically, and Ag modified Pd largely electronically. Cu added by SR modified Pd electronically to a small extent, but preferentially decorated the low-coordination sites of Pd such that the ethylene selectivity of the optimum catalyst was significantly promoted from that of Pd, while its activity remained comparable to that of Pd. The sensitivity of ethylene selectivity to the surface structure of Pd was demonstrated using model catalysts containing uniform-sized Pd particles in either cubic or spherical shapes. The three stage deactivation of the Pd catalyst and the self-regenerative behavior in early stages of deactivation were also investigated. © 2011 Elsevier B.V. All rights reserved.

Lee J.,Seoul National University
Astrophysical Journal | Year: 2012

We investigate the effect of coupled dark energy (cDE) on the spin alignments in isolated pairs of galactic halos using the publicly available data from the hydrodynamic cDE simulations (H-CoDECs) that were run for various cDE models such as EXP001, EXP002, EXP003 (with exponential potential and constant coupling), EXP008e3 (with exponential potential and exponential coupling), and SUGRA003 (with supergravity potential and negative constant coupling), as well as for a standard ΛCDM cosmology (with the WMAP7 parameters). Measuring the cosines of the angles between the spin axes in isolated pairs of galactic halos for each model and determining its probability density distribution, we show that for the SUGRA003 model with bouncing cDE the null hypothesis of no spin alignment in pairs of galactic halos is rejected at a 99.999% confidence level. In contrast, the ΛCDM cosmology yields no significant signal of spin alignment, and the other four cDE models also exhibit only weak signals of spin alignments. The strength of the spin alignment signal is found to be almost independent of the total halo mass and separation distance in galaxy pairs. Showing also that no signal is detected from the Sloan Digital Sky Survey DR 7, we conclude that the spin alignments in galaxy pairs are in principle a unique test of bouncing cDE models. © 2012. The American Astronomical Society. All rights reserved..

Zhang J.,Nanyang Technological University | Hong S.H.,Seoul National University
Organic Letters | Year: 2012

Direct N-acylation of lactams, oxazolidinones, and imidazolidinones was achieved with aldehydes by Shvo's catalyst without using any other stoichiometric reagent. The N-acylations with α,β-unsaturated aldehydes were achieved with excellent yields. © 2012 American Chemical Society.

As China's capital, Beijing has attracted a large number of rural migrants and, as a result, the number of migrant settlements experienced a rapid increase. However, after reaching their peak in 1990s, most of Beijing's migrant settlements either disappeared or were forced out from their original locations to more remote, impoverished areas. Based on an ethnographic study, this research highlights the uneven relationships among suburban villagers, rural migrants, government agencies, and real estate developers, as they engage in the reconfiguration of migrant settlements with different aims and interests. By analyzing the conflict, struggle, and negotiation of space in the urban redevelopment process and the interaction between different government agencies and various social groups, this research provides deeper insight into a dramatic shift from a low-end alliance between local Beijing villagers and migrants to a high-end alliance between the Beijing government and large-scale real estate developers. This analysis on the recent restructuring of post-reform urban space in Beijing's migrant settlements will then emphasize the need to examine the intimate relationship between the hukou system and land use rights during the urban redevelopment process. © 2011 Elsevier Ltd.

Because common complex diseases are affected by multiple genes and environmental factors, it is essential to investigate gene-gene and/or gene-environment interactions to understand genetic architecture of complex diseases. After the great success of large scale genome-wide association (GWA) studies using the high density single nucleotide polymorphism (SNP) chips, the study of gene-gene interaction becomes a next challenge. Multifactor dimensionality reduction (MDR) analysis has been widely used for the gene-gene interaction analysis. In practice, however, it is not easy to perform high order gene-gene interaction analyses via MDR in genome-wide level because it requires exploring a huge search space and suffers from a computational burden due to high dimensionality. We propose dimensional reduction analysis, Gene-MDR analysis for the fast and efficient high order gene-gene interaction analysis. The proposed Gene-MDR method is composed of two-step applications of MDR: within- and between-gene MDR analyses. First, within-gene MDR analysis summarizes each gene effect via MDR analysis by combining multiple SNPs from the same gene. Second, between-gene MDR analysis then performs interaction analysis using the summarized gene effects from within-gene MDR analysis. We apply the Gene-MDR method to bipolar disorder (BD) GWA data from Wellcome Trust Case Control Consortium (WTCCC). The results demonstrate that Gene-MDR is capable of detecting high order gene-gene interactions associated with BD. By reducing the dimension of genome-wide data from SNP level to gene level, Gene-MDR efficiently identifies high order gene-gene interactions. Therefore, Gene-MDR can provide the key to understand complex disease etiology.

Chen D.Y.-K.,Seoul National University | Pouwer R.H.,Griffith University | Richard J.-A.,Institute of Chemical and Engineering Sciences, Singapore
Chemical Society Reviews | Year: 2012

In this tutorial review, recent advances in the synthesis of cyclopropane-containing natural products are discussed, highlighting the application of novel synthetic methodologies and innovative synthetic strategies in the construction of highly functionalized cyclopropanes. The examples showcased herein aim to inspire students and practitioners of organic synthesis to seek further advances in the chemical synthesis of cyclopropanes, both in the context of target-oriented syntheses and method developments. © 2012 The Royal Society of Chemistry.

Chang J.S.,Seoul National University
Journal of Transport Geography | Year: 2010

This paper considers a way of assessing travel time reliability in transport appraisal. The term travel time reliability generally refers to variations in journey time that travellers may not predict. Two essential requirements for the evaluation and guidance of the appraisal are discussed. The requirements represent the measurement and valuation of travel time uncertainties. The gap between actual and planned journey times is used for the quantification, subject to the differing characteristics of road and rail usage. A logit-based choice model is developed to derive monetary values of travel time variation. Guidelines are established using the standard framework of the rule of a half. Concluding remarks are also presented. © 2009 Elsevier Ltd. All rights reserved.

Lee J.,Seoul National University | Choi Y.-Y.,Kyung Hee University
Astrophysical Journal | Year: 2015

We report a detection of the effect of the large-scale velocity shear on the spatial distributions of the galactic satellites around the isolated hosts. Identifying the isolated galactic systems, each of which consists of a single host galaxy and its satellites, from the Seventh Data Release of the Sloan Digital Sky Survey and reconstructing linearly the velocity shear field in the local universe, we measure the alignments between the relative positions of the satellites from their isolated hosts and the principal axes of the local velocity shear tensors projected onto the plane of sky. We find a clear signal that the galactic satellites in isolated systems are located preferentially along the directions of the minor principal axes of the large-scale velocity shear field. Those galactic satellites that are spirals, are brighter, are located at distances larger than the projected virial radii of the hosts, and belong to the spiral hosts yield stronger alignment signals, which implies that the alignment strength depends on the formation and accretion epochs of the galactic satellites. It is also shown that the alignment strength is quite insensitive to the cosmic web environment, as well as the size and luminosity of the isolated hosts. Although this result is consistent with the numerical finding of Libeskind et al. based on an N-body experiment, owing to the very low significance of the observed signals, it remains inconclusive whether or not the velocity shear effect on the satellite distribution is truly universal. © 2015. The American Astronomical Society. All rights reserved.

Lee D.,Seoul National University | Li P.Y.,University of Minnesota
IEEE Transactions on Automatic Control | Year: 2013

We show the fundamental passive decomposition property of general mechanical systems on a n-dim. configuration manifold M, i.e., when endowed with a submersion h:M→N , where N is a m-dim. manifold (m≤n), their Lagrangian dynamics with the kinetic energy as the Lagrangian can always be decomposed into: 1) shape system, describing the m-dim. dynamics of h(q) on N ; 2) locked system, representing the (n-m)-dim. dynamics along the level set of h; and 3) energetically-conservative coupling between them. The locked and shape systems also individually inherit the Lagrangian structure and passivity of the original dynamics. We exhibit and analyze geometric and energetic properties of the passive decomposition in a coordinate-free manner. An illustrative example on SO(3) is also provided. © 2012 IEEE.

Pyun J.,University of Arizona | Pyun J.,Seoul National University
Angewandte Chemie - International Edition | Year: 2012

No, it's not frogspawn! Polymer-coated gold nanoparticles can be assembled into extended mesoscopic chains with precise dimensional control. Here, the conditions can be adjusted to promote the fusion of polymeric ligands into cylindrical micellar aggregates. This type of colloidal polymerization offers a new and versatile route to a variety of mesoscopic assemblies of nanoparticles. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tanwani A.,French Institute for Research in Computer Science and Automation | Shim H.,Seoul National University | Liberzon D.,University of Illinois at Urbana - Champaign
IEEE Transactions on Automatic Control | Year: 2013

This paper presents a characterization of observability and an observer design method for switched linear systems with state jumps. A necessary and sufficient condition is presented for observability, globally in time, when the system evolves under predetermined mode transitions. Because this characterization depends upon the switching signal under consideration, the existence of singular switching signals is studied alongside developing a sufficient condition that guarantees uniform observability with respect to switching times. Furthermore, while taking state jumps into account, a relatively weaker characterization is given for determinability, the property that concerns with recovery of the original state at some time rather than at all times. Assuming determinability of the system, a hybrid observer is designed for the most general case to estimate the state of the system and it is shown that the estimation error decays exponentially. Since the individual modes of the switched system may not be observable, the proposed strategy for designing the observer is based upon a novel idea of accumulating the information from individual subsystems. Contrary to the usual approach, dwell-time between switchings is not necessary, but the proposed design does require persistent switching. For practical purposes, the calculations also take into account the time consumed in performing computations. © 1963-2012 IEEE.

Kim J.,Samsung | Lee J.,Hyundai Motor Company | Cho B.H.,Seoul National University
IEEE Transactions on Industrial Electronics | Year: 2013

This approach investigates with an equivalent circuit modeling a polymer electrolyte membrane (PEM) fuel cell degradation combined with a low-frequency ripple current (LFRC) that may shorten the fuel cell life and worsen the fuel efficiency. Through the immediate measurement of the impedance curves on single cells obtained after cycling for hours and operating in cathode flooding and membrane dehydration modes at variable frequencies, it has been shown that the impedance magnitude of a fuel cell injecting a LFRC increased when compared with that of a high-frequency ripple current. This study develops these investigations one step further by designing equivalent circuit elements like resistance and capacitance by electrochemical impedance spectroscopy. Impedance-based model is able to describe the dynamic behavior of the PEM fuel cell. For validation of the proposed fuel cell model, an experimental study has been carried out for a 1.2-kW Nexa module. © 1982-2012 IEEE.

Lee M.S.,Seoul National University
Information Sciences | Year: 2013

Wang et al. [B. Wang, Q. Wu, Y. Hu, Information Sciences 177 (2007)] proposed a knapsack-based probabilistic encryption scheme with non-binary coefficients which enjoys a high density larger than 1.06 in the worst case. In this work, we successfully attack this scheme by showing that a public key and a restriction on system parameters allow the attacker to recover a secret key in a cubic time complexity using modular equations. This approach is much more efficient than the previous attack by Youssef [A.M. Youssef, Information Sciences 179 (2009)], in which lattice basis reductions are used. Recovering secret keys can be done within 4 h and 4 days when n = 100 and 200, respectively. A simple modification that helps resist known attacks is also discussed. © 2012 Elsevier Inc. All rights reserved.

Lee S.S.,Seoul National University
Clinical and molecular hepatology | Year: 2012

The aim of this study was to describe the types and causes of liver disease in patients from a single community hospital in Korea between April 2005 and May 2010. A cohort of patients who visited the liver clinic of the hospital during the aforementioned time period were consecutively enrolled (n=6,307). Consistent diagnostic criteria for each liver disease were set by a single, experienced hepatologist, and the diagnosis of all of the enrolled patients was confirmed by retrospective review of their medical records. Among the 6,307 patients, 528 (8.4%) were classified as acute hepatitis, 3,957 (62.7%) as chronic hepatitis, 767 (12.2%) as liver cirrhosis, 509 (8.1%) as primary liver cancer, and 546 (8.7%) as a benign liver mass or other diseases. The etiologies in the acute hepatitis group in decreasing order of prevalence were hepatitis A (44.3%), toxic hepatitis (32.4%), other hepatitis viruses (13.8%), and cryptogenic hepatitis (9.1%). In the chronic hepatitis group, 51.2% of cases were attributed to viral hepatitis, 33.3% to nonalcoholic fatty liver disease, and 13.0% to alcoholic liver disease (ALD). Of the cirrhoses, 73.4% were attributable to viral causes and 18.1% to alcohol. Of the hepatocellular carcinoma cases, 86.6% were attributed to viral hepatitis and 11.6% to ALD. Among the benign tumors, hemangioma comprised 52.2% and cystic liver disease comprised 33.7%. Knowledge of the current status of the type and cause of liver disease in Korea may be valuable as a basis for evaluating changing trends in liver disease in that country.

Chen D.Y.-K.,Seoul National University
Synlett | Year: 2011

In this Account, recent advances in the total synthesis of complex molecular architectures originating from the authors laboratory are highlighted and discussed. Through thoughtful planning, intelligence gathering, and often serendipitous discoveries, a diverse collection of natural products spanning several structural classes have been successfully synthesized. The valuable information garnered from these synthetic campaigns showcases the unparalleled and undisputed value of this historical discipline and its cemented role in advancing synthetic organic chemistry to new heights and horizons. 1 Introduction 2 Total Synthesis of the Thiopeptide Antibiotics 3 Total Synthesis of the Cytotoxic Marine Macrolide, Palmerolide A 4 Total Synthesis of the Fab-Inhibitory Antibiotics, Platensimycin and Platencin 5 Total Synthesis of the Antiangiogenic Agents, the Cortistatins 6 Total Synthesis of the Resveratrol-Derived Bioactive Polyphenols, Hopeanol and Hopeahainol A 7 Total Synthesis of the Dimeric Bis-indole Alkaloid, Haplophytine 8 Total Synthesis of the Novel Sesquiterpenoids, Echinopine A and B 9 Total Synthesis of the Selective Cytotoxic Agent towards Renal Cancer Cells, Englerin A 10 Formal Synthesis of the Furanobis-indole Alkaloid, Phalarine 11 Total Synthesis of the Neuroprotective Agent, Nanolobatolide 12 Conclusion.© Georg Thieme Verlag Stuttgart · New York.

Hahn S.,Seoul National University
The Cochrane database of systematic reviews | Year: 2013

Meconium aspiration syndrome (MAS) can occur when a newborn infant inhales a mixture of meconium and amniotic fluid into the lungs around the time of delivery. Other than supportive measures, little effective therapy is available. Lung lavage may be a potentially effective treatment for MAS by virtue of removing meconium from the airspaces and altering the natural course of the disease. To evaluate the effects of lung lavage on morbidity and mortality in newborn infants with MAS. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, and EMBASE up to December 2012; previous reviews including cross-references, abstracts, and conference proceedings; and expert informants. We contacted authors directly to obtain additional data. We used the following subject headings and text words: meconium aspiration, pulmonary surfactants, fluorocarbons, bronchoalveolar lavage, lung lavage, pulmonary lavage. Randomised controlled trials that evaluated the effects of lung lavage in infants with MAS, including those intubated for the purpose of lavage. Lung lavage was defined as any intervention in which fluid is instilled into the lung that is followed by an attempt to remove it by suctioning and/or postural drainage. The review authors extracted from the reports of the clinical trial, data regarding clinical outcomes, including mortality, requirement for extracorporeal membrane oxygenation (ECMO), pneumothorax, duration of mechanical ventilation and oxygen therapy, length of hospital stay, indices of pulmonary function, and adverse effects of lavage. Data analysis was done in accordance with the standards of the Cochrane Neonatal Review Group. Only four small randomised controlled trials fulfilled the selection criteria. For one of these trials, no data are available for the control group. Two studies compared lavage using diluted surfactant with standard care. Meta-analysis of these two studies did not show a significant effect on mortality (typical relative risk 0.42, 95% confidence interval [CI] 0.12 to 1.46; typical risk difference -0.10, 95% CI -0.24 to 0.04) or the use of ECMO (typical relative risk 0.27, 95% CI 0.04 to 1.86; typical risk difference -0.15, 95% CI -0.35 to 0.04). For the composite outcome of death or use of ECMO, a significant effect favoured the lavage group (typical relative risk 0.33, 95% CI 0.11 to 0.96; typical risk difference -0.19, 95% CI -0.34 to -0.03; number needed to benefit [NNTB] 5). No other benefits were reported. The other published study compared surfactant lavage followed by a surfactant bolus with surfactant bolus therapy alone in MAS complicated by pulmonary hypertension. No significant improvements in mortality, pneumothorax, duration of mechanical ventilation. or duration of hospitalisation were observed. In infants with meconium aspiration syndrome, lung lavage with diluted surfactant may be beneficial, but additional controlled clinical trials of lavage therapy should be conducted to confirm the treatment effect, to refine the method of lavage treatment, and to compare lavage treatment with other approaches, including surfactant bolus therapy. Long-term outcomes should be evaluated in further clinical trials.

Auxin and brassinosteroid (BR) play essential roles in diverse aspects of growth and developmental processes in plants mainly through coordinate regulation of cell division, elongation, and differentiation. Consistent with the overlapped roles, accumulating evidence indicates that the two growth hormones act in a synergistic as well as in an interdependent manner in many cases, although the underlying molecular mechanisms are not fully understood. Here, we demonstrate that auxin and BR signaling pathways are interconnected at the transcriptional level via a negative feedback loop. An Arabidopsis activating tagging mutant dlf-1D exhibited dwarfed growth with small, dark-green leaves and reduced fertility. Hormone feeding assays revealed that the mutant phenotype is caused by the reduction of endogenous BR level. Consistent with this, a gene encoding the CYP72C1 enzyme that catabolizes BR was up-regulated. Notably, the transcript level of the ARF8 transcription factor gene, which modulates the expression of auxin-responsive genes, was significantly elevated in the mutant. In addition, the ARF8 gene expression was significantly reduced by BR but induced by brassinazole, a BR biosynthetic inhibitor. On the other hand, two BR catabolic pathway genes, DLF (CYP72C1) and BAS1, were induced by auxin. Our observations indicate that at least part of auxin and BR signaling pathways are unified through a transcriptional feedback control of the DLF and ARF8 genes.

Lee E.-J.,Seoul National University
Computers in Human Behavior | Year: 2010

The present experiment investigated if anthropomorphic interfaces facilitate people's tendency to project social expectations onto computers and how such effects might vary depending on users' cognitive style. In a 2 (synthetic vs. recorded speech) × 2 (flattering vs. generic feedback) × 2 (low vs. high rationality) × 2 (low vs. high experientiality) experiment, participants played a trivia game with a computer. Use of recorded speech did not amplify the previously documented flattery effects (Fogg & Nass, 1997), challenging the notion that anthropomorphism will promote social responses to computers. Participants evaluated the human-voiced computer more positively and conformed more to its suggestions than the one using synthetic speech, but such effects were found only among less analytical or more intuition-driven individuals, suggesting dispositional differences in people's susceptibility to anthropomorphic cues embedded in the interface. © 2009 Elsevier Ltd. All rights reserved.

Joo C.,Technical University of Delft | Fareh M.,Technical University of Delft | Narry Kim V.,Seoul National University
Trends in Biochemical Sciences | Year: 2013

Single-molecule fluorescence spectroscopy offers real-time, nanometer-resolution information. Over the past two decades, this emerging single-molecule technique has been rapidly adopted to investigate the structural dynamics and biological functions of proteins. Despite this remarkable achievement, single-molecule fluorescence techniques must be extended to macromolecular protein complexes that are physiologically more relevant for functional studies. In this review, we present recent major breakthroughs for investigating protein complexes within cell extracts using single-molecule fluorescence. We outline the challenges, future prospects and potential applications of these new single-molecule fluorescence techniques in biological and clinical research. © 2012 Elsevier Ltd.

Min J.-Y.,Seoul National University | Min K.-B.,Ajou University
Dementia and Geriatric Cognitive Disorders | Year: 2014

Background: Oxidative stress is implicated in the pathogenesis of Alzheimer's disease (AD). Accumulating evidence shows that antioxidant-rich food reduces the risk of AD by inhibiting oxidative stress. This study investigates whether serum levels of carotenoids were associated with the risk of AD mortality in a nationally representative sample of US adults. Methods: We used data from the Third Nutrition and Health Examination Survey (NHANES III) database and the NHANES III Linked Mortality File. A total of 6,958 participants aged older than 50 years were included in this study. Results: We found that high serum levels of lycopene and lutein+zeaxanthin at baseline were associated with a lower risk of AD mortality after adjustment for potential covariates. The reduction in the mortality risk was progressively raised by increasing serum lycopene (HR = 0.26, 95% CI 0.10-0.69) and lutein+zeaxanthin (HR = 0.43, 95% CI 0.22-0.85) levels. In contrast, no associations with AD mortality were observed for other serum carotenoids, including alpha-carotene, beta-carotene, and beta-cryptoxanthin. Conclusion: High serum levels of lycopene and lutein+zeaxanthin are associated with a lower risk of AD mortality in adults. Our findings suggest that a high intake of lycopene-or lutein+zeaxanthin-rich food may be important for reducing the AD mortality risk. © 2013 S. Karger AG, Basel.

Choi J.-Y.,Yonsei University | Lee J.-M.,Seoul National University | Sirlin C.B.,University of California at San Diego
Radiology | Year: 2014

Computed tomography (CT) and magnetic resonance (MR) imaging play critical roles in the diagnosis and staging of hepatocellular carcinoma (HCC). The second article of this two-part review discusses basic concepts of diagnosis and staging, reviews the diagnostic performance of CT and MR imaging with extracellular contrast agents and of MR imaging with hepatobiliary contrast agents, and examines in depth the major and ancillary imaging features used in the diagnosis and characterization of HCC. © RSNA, 2014.

Hwang I.C.,Seoul National University
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery | Year: 2013

The prognostic value of B-type natriuretic peptide (BNP) for surgical outcome in patients with mitral regurgitation (MR) has not been studied. The purpose of this study was to determine the prognostic value of BNP in patients with chronic severe MR, undergoing mitral valve surgery. In total, 117 patients with chronic severe MR undergoing surgery were evaluated from the MR registry of Seoul National University Hospital. Patients were excluded if they had acute MR or acutely decompensated heart failure, and significant renal, pulmonary, coronary or other significant valvular heart disease. The plasma BNP level assay and echocardiographic studies were done before surgery. Study endpoint was a composite of cardiac death and cardiac hospitalization during follow-up. The median duration of the follow-up was 4.5 years, and the study endpoint was reached in 11 (9.4%) patients. Receiver-operating characteristic curve analysis yielded an optimal cut-off point of 125 pg/ml for BNP that distinguished patients with poor prognosis. Kaplan-Meier survival analysis with the log-rank test and multivariate Cox proportional hazards model showed that patients with BNP ≥125 pg/ml had a worse clinical outcome after surgery (log rank 7.606, P = 0.006; adjusted hazard ratio = 5.536 [95% confidence interval 1.189-25.788], P = 0.029). Among patients with chronic severe MR undergoing mitral valve surgery, BNP independently predicts the poor clinical outcome. The BNP measurement should be considered in the risk stratification of these patients.

Rey S.-J.,Seoul National University | Rosenhaus V.,University of California at Berkeley
Journal of High Energy Physics | Year: 2014

We establish resolution bounds on reconstructing a bulk field from boundary data on a timelike hypersurface. If the bulk only supports propagating modes, reconstruction is complete. If the bulk also supports evanescent modes, local reconstruction is not achievable unless one has exponential precision in knowledge of the boundary data. Without exponential precision, for a Minkowski bulk, one can reconstruct a spatially coarse-grained bulk field, but only out to a depth set by the coarse-graining scale. For an asymptotically AdS bulk, reconstruction is limited to a spatial coarse-graining proper distance set by the AdS scale. AdS black holes admit evanescent modes. We study the resolution bound in the large AdS black hole background and provide a dual CFT interpretation. Our results demonstrate that, if there is a black hole of any size in the bulk, then sub-AdS bulk locality is no longer well-encoded in boundary data in terms of local CFT operators. Specifically, in order to probe the bulk on sub-AdS scales using only boundary data in terms of local operators, one must either have such data to exponential precision or make further assumptions about the bulk state. © 2014 The Author(s).

Yoon Y.,Seoul National University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We show that Mannheim's conformal gravity program, whose potential has a term proportional to 1/r and another term proportional to r, does not reduce to Newtonian gravity at short distances, unless one assumes undesirable singularities of the mass density of the proton. Therefore, despite the claim that it successfully explains galaxy rotation curves, unless one assumes the singularities, it seems to be falsified by numerous Cavendish-type experiments performed at laboratories on Earth whose work have not found any deviations from Newton's theory. Moreover, it can be shown that as long as the total mass of the proton is positive, Mannheim's conformal gravity program leads to negative linear potential, which is problematic from the point of view of fitting galaxy rotation curves, which necessarily requires positive linear potential. © 2013 American Physical Society.

Vemareddy P.,Physical Research Laboratory | Ambastha A.,Physical Research Laboratory | Maurya R.A.,Seoul National University
Astrophysical Journal | Year: 2012

We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region (AR) NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots, one connected to a flare-prone region and another with coronal mass ejection (CME). The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of major eruptive events. Further, temporal profiles of twist parameters, namely, average shear angle, αav, αbest, derived from HMI vector magnetograms, and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, correspond well with the rotational profile of the sunspot in the CME-prone region, giving predominant evidence of rotational motion causing magnetic non-potentiality. Moreover, the mean value of free energy from the virial theorem calculated at the photospheric level shows a clear step-down decrease at the onset time of the flares revealing unambiguous evidence of energy release intermittently that is stored by flux emergence and/or motions in pre-flare phases. Additionally, distribution of helicity injection is homogeneous in the CME-prone region while in the flare-prone region it is not and often changes sign. This study provides a clear picture that both proper and rotational motions of the observed fluxes played significant roles in enhancing the magnetic non-potentiality of the AR by injecting helicity, twisting the magnetic fields and thereby increasing the free energy, leading to favorable conditions for the observed transient activity. © 2012. The American Astronomical Society. All rights reserved..

Up-to-date, quantitative angiographic measurement of revascularization extent after bypass surgery has not been reported. To measure the extent of angiographic revascularization quantitatively 6 months postoperatively with the OSIRIS program (University Hospital of Geneva, version 3.1). A total of 75 bypass procedures were performed in 65 consecutive adult moyamoya disease patients, and 71 bypass surgeries in 61 adult moyamoya disease patients were studied 6 months postoperatively with angiography. We performed 5 different types of bypass surgeries: encephaloduroarteriosynangiosis (EDAS), superficial temporal artery-middle cerebral artery anastomosis (SMA), SMA with encephalomyosynangiosis (EMS), SMA with EDAS, and SMA with encephaloduroarteriomyosynangiosis (EDAMS). We also investigated single-photon emission computed tomography (SPECT) results after 6 months postoperatively and compared the angiographic revascularization extent with the SPECT results. The mean values for the extent of revascularization among 5 different bypass surgeries were as follows: 32.4% for EDAS only, 57.4% for SMA only, 58.4% for SMA with EMS, 66.1% for SMA with EDAS, and 70.8% for SMA with EDAMS. There was a statistically significant difference in the extent of revascularization among the 5 surgical modalities (P = .000) and between the EDAS-only group and various SMA groups (P = .000). Statistical analysis between angiographic revascularization extent and SPECT results demonstrated significant statistical correlation (P = .000). The extent of angiographic revascularization in adult moyamoya disease patients was highest in the SMA with EDAMS group and lowest in the EDAS-only group. In addition, angiographic revascularization extent was well correlated with the change in SPECT.

Lee S.,University of Maryland College Park | Youn B.D.,Seoul National University
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2011

This paper presents an advanced design concept for a piezoelectric energy harvesting (EH), referred to as multimodal EH skin. This EH design facilitates the use of multimodal vibration and enhances power harvesting efficiency. The multimodal EH skin is an extension of our previous work, EH skin, which was an innovative design paradigm for a piezoelectric energy harvester: a vibrating skin structure and an additional thin piezoelectric layer in one device. A computational (finite element) model of the multilayered assembly-the vibrating skin structure and piezoelectric layer-is constructed and the optimal topology and/or shape of the piezoelectric layer is found for maximum power generation from multiple vibration modes. A design rationale for the multimodal EH skin was proposed: designing a piezoelectric material distribution and external resistors. In the material design step, the piezoelectric material is segmented by inflection lines from multiple vibration modes of interests to minimize voltage cancellation. The inflection lines are detected using the voltage phase. In the external resistor design step, the resistor values are found for each segment to maximize power output. The presented design concept, which can be applied to any engineering system with multimodal harmonic-vibrating skins, was applied to two case studies: an aircraft skin and a power transformer panel. The excellent performance of multimodal EH skin was demonstrated, showing larger power generation than EH skin without segmentation or unimodal EH skin. © 2011 IEEE.

Ahn S.J.,Seoul National University
Korean journal of ophthalmology : KJO | Year: 2010

To evaluate the clinical features, associated factors, and treatment outcomes of scleritis in the Korean population. Medical records were retrospectively reviewed for 94 eyes of 76 patients with scleritis. Clinical features of scleritis, including systemic disease, presence of microorganisms, serologic markers, history of previous ocular surgery, and use of immunosuppressants were investigated and compared amongst the subtypes of scleritis. Treatment outcomes were evaluated using best corrected visual acuity (BCVA) and time to scleritis remission. Nodular scleritis was the most common form observed, followed by necrotizing scleritis with inflammation, diffuse scleritis, and necrotizing scleritis without inflammation, respectively. A total of 16 of 76 patients (21.1%) had connective tissue diseases. Eleven cases (14.5%) had infectious scleritis, of which bacteria (54.5%) and fungi (45.5%) were the causative microorganisms. Thirty-three patients (43.4%) had previous ocular surgery, mostly pterygium excision. Notably, a history of pterygium excision was significantly associated with development of necrotizing and infectious scleritis (odds ratio [OR], 399 and 10.1; p < 0.001 and 0.002, respectively). In addition, patients with necrotizing scleritis were more likely to have infectious scleritis (OR, 11.7; p = 0.001). BCVA after treatment and time to remission also showed significant differences among the different scleritis subtypes. Systemic immunosuppression was required in addition to steroids for treating diffuse and necrotizing scleritis. Careful taking of patient history including previous pterygium excision should be performed, especially in patients with necrotizing and infectious scleritis. In addition, evaluation of microbiological infection can be crucial for patients with necrotizing scleritis and history of pterygium excision.

Theato P.,Johannes Gutenberg University Mainz | Theato P.,Seoul National University | Theato P.,University of Sheffield
Angewandte Chemie - International Edition | Year: 2011

Worth one's while: The careful use of a single chromophore on methodically designed polymers can be sufficient to modify polymer properties. Recent examples range from controlled micelle destruction and light-controlled precipitation in aqueous solution to the fabrication of nanoporous thin films (see schematic illustration of the use of a photocleavable block copolymer as a template for a nanoporous thin film). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dev P.S.B.,University of Manchester | Pilaftsis A.,University of Manchester | Pilaftsis A.,CERN | Yang U.-K.,Seoul National University
Physical Review Letters | Year: 2014

We study a new production mechanism for heavy neutrinos at the LHC, which dominates over the usually considered s-channel W-exchange diagram for heavy-neutrino masses larger than 100-200 GeV. The new mechanism is infrared enhanced by t-channel Wγ-fusion processes. This has important implications for experimental tests of the seesaw mechanism of neutrino masses and, in particular, for the ongoing heavy neutrino searches at the LHC. We find that the direct collider limits on the light-to-heavy neutrino mixing can be significantly improved when this new production channel is properly taken into account. The scope of this new mechanism can be equally well extended to other exotic searches at the LHC. © 2014 American Physical Society.

Yi H.,Seoul National University
Nucleic acids research | Year: 2011

Next-generation sequencing has great potential for application in bacterial transcriptomics. However, unlike eukaryotes, bacteria have no clear mechanism to select mRNAs over rRNAs; therefore, rRNA removal is a critical step in sequencing-based transcriptomics. Duplex-specific nuclease (DSN) is an enzyme that, at high temperatures, degrades duplex DNA in preference to single-stranded DNA. DSN treatment has been successfully used to normalize the relative transcript abundance in mRNA-enriched cDNA libraries from eukaryotic organisms. In this study, we demonstrate the utility of this method to remove rRNA from prokaryotic total RNA. We evaluated the efficacy of DSN to remove rRNA by comparing it with the conventional subtractive hybridization (Hyb) method. Illumina deep sequencing was performed to obtain transcriptomes from Escherichia coli grown under four growth conditions. The results clearly showed that our DSN treatment was more efficient at removing rRNA than the Hyb method was, while preserving the original relative abundance of mRNA species in bacterial cells. Therefore, we propose that, for bacterial mRNA-seq experiments, DSN treatment should be preferred to Hyb-based methods.

Hepatitis B virus X protein (HBx) contributes to the development of hepatocellular carcinoma (HCC), probably by regulating activities of many host or viral proteins through protein–protein interactions. In this study, we identified poly(ADP-ribose) polymerase (PARP1), a crucial factor in DNA repair, as an HBx-interacting protein using a proteomics approach. Coimmunoprecipitation and proximity ligation assays confirmed the binding and colocalization of HBx and PARP1 in the nucleus. The carboxyl-terminus of HBx protein bound to the catalytic domain of PARP1, and this binding reduced the enzymatic activity of PARP1 in both in vitro and in vivo assays. HBx interrupted the binding of PARP1 to Sirt6, which catalyzes the mono-ADP-ribosylation required for DNA repair. Consistently, overexpression of HBx inhibited the clearance of γH2AX DNA repair foci generated under oxidative stress in Chang liver cells. Recruitment of the DNA repair complex to the site-specific double-strand breaks was inhibited in the presence of HBx, when measured by laser microirradiation assay and damage-specific chromatin immunoprecipitation assays. Consequently, HBx increased signs of DNA damage such as accumulation of 8-hydroxy-2′-deoxyguanosine and comet formation, which were reversed by overexpression of PARP1 and/or Sirt6. Finally, the interaction between PARP1 and Sirt6 was markedly lower in the livers of HBx-transgenic mice and specimens obtained from HCC patients to compare with the corresponding control. Our data suggest that the physical interaction of HBx and PARP1 accelerates DNA damage by inhibiting recruitment of the DNA repair complex to the damaged DNA sites, which may lead to the onset of hepatocarcinogenesis.Oncogene advance online publication, 4 April 2016; doi:10.1038/onc.2016.82. © 2016 Macmillan Publishers Limited

Lee C.-Y.,Seoul National University | Kim J.-H.,Korea Aerospace University
Composite Structures | Year: 2013

This work considers the postbuckling behaviors of Functionally Graded Material (FGM) plate in hygrothermal environments. Basically, the structures change continuously in the thickness direction according to the volume fractions of the material. For the description of the model, the first-order shear deformation theory (FSDT) is used, and von Karman strain-displacement relations are applied. In the analysis, finite element method and Newton-Raphson technique are adopted to analyze the thermal postbuckling behavior of the model. Furthermore, a simple power-law is employed in the thickness direction of the plate, and the temperature and moisture effects are fully investigated in this study. To check the validity of the present work, comparisons with the previous results are performed. And then, moisture effects on the model are significantly appeared due to the increase of the volume fraction index of the materials. © 2012 Elsevier Ltd.

Lee J.,Seoul National University
Astrophysical Journal | Year: 2012

Those galaxy clusters that do not belong to superclusters are referred to as isolated clusters. Their relative abundance at a given epoch may be a powerful constraint of the dark energy equation of state since it depends strongly on how fast the structures grow on the largest scale in the universe. We note that the mass function of isolated clusters can be separately evaluated through modification of the recently developed Corasaniti-Achitouv (CA) theory according to which the stochastic collapse barrier is quantified by two coefficients: the drifting average coefficient (β) and the diffusion coefficient (DB ). Regarding β in the CA formalism as an adjustable parameter and assuming that the formation of isolated clusters corresponds to the case of DB = 0, we determine the mass function of isolated clusters by fitting the numerical results from the MICE simulations to the modified CA formula. It is found that the best-fit value of β changes with redshift and that the CA mass function with DB = 0 agrees very well with the numerical results at various redshifts. Defining the relative abundance of isolated clusters, ξI, as the ratio of the cumulative mass function of isolated clusters to that of non-isolated clusters at a given epoch, we finally show how sensitively ξI changes with the dark energy equation of state. It is also discussed how ξI can help break the degeneracy between the dark energy equation of state and the other key cosmological parameters. © 2012. The American Astronomical Society. All rights reserved..

Krutmann J.,IUF Leibniz Research Institute for Environmental Medicine | Morita A.,Nagoya City University | Chung J.H.,Seoul National University
Journal of Investigative Dermatology | Year: 2012

The health consequences of sun exposure have concerned mankind for more than 100 years. Recent molecular studies in photodermatology have greatly advanced our understanding of this important topic. We will illustrate this progress by focusing on the following selected topics: (i) the nature of the DNA damage-independent part of the UVB response of human skin and the role of the arylhydrocarbon receptor in cutaneous biology, (ii) the contribution of wavelengths beyond the UV spectrum to solar radiation-induced skin damage, (iii) the emerging evidence that subcutaneous fat is a target tissue for sunlight, and (iv) the most recent insight into the mode of action of phototherapy. © 2012 The Society for Investigative Dermatology.

Kim J.Y.,Seoul National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2011

This study was performed to evaluate whether the prevalence rates of primary antibiotic resistance in Helicobacter pylori (H. pylori) isolates and the eradication rate of H. pylori could be different between cancer and non-cancer patients. H. pylori were isolated from gastric mucosal biopsy specimens obtained from 269 Koreans, who did not have any eradication therapy history and were diagnosed as one of the following diseases; chronic gastritis, benign gastric ulcer, duodenal ulcer or gastric cancer. The susceptibilities of the H. pylori isolates to amoxicillin, clarithromycin, metronidazole, tetracycline, azithromycin, ciprofloxacin, levofloxacin and moxifloxacin were examined with the agar dilution method. In addition, eradication rate of H. pylori was evaluated. There was no significant difference in the primary antibiotic resistance to above eight antibiotics among chronic gastritis, peptic ulcer disease and gastric cancer. Furthermore there was no difference of antibiotic resistance between cancer and non-cancer patients, and there was no difference of eradication rate of H. pylori according to disease. Primary antibiotic resistance and H. pylori eradication rate were not different between cancer and non-cancer patients.

Yoo K.-Y.,Seoul National University
Asian Pacific Journal of Cancer Prevention | Year: 2010

Cancer incidences as well as the most prevalent cancer types vary greatly across Asian countries since people have differing health behaviors as well as lifestyle factors related to cancer risk. Countries have varying systems of government organization, laws, resources, facilities, and management strategies for addressing the cancer burden. Examples such as Korea and Japan with existing national cancer control programs need to focus on early screening and detection and quality of screening methods. If screening and detection increase to cover more than 50% of the target population, survival rate increases and thus the number of cancer patients detected increases resulting in higher medical cost. Thus, expansion of cancer screening, in addition to smoking prevention, immunization increase, and diet control awareness, are needed for cancer prevention strategies. Countries such as Thailand, China, Malaysia, and Turkey need to begin organized efforts to reduce cancer deaths through state-wide cancer screening programs. Strategies focused on increasing survival among cancer patients are also needed. In addition, government organizations and law regulations need to be in place as the first step towards cancer prevention. For the countries such as Nepal, Pakistan, Mongolia, and Iraq which do not have any cancer-related organizations in place, the first step that is needed is to raise public awareness about cancer; a public awareness campaign is the number one priority and should begin immediately. The easiest and most feasible step at this point is dissemination of cancer education materials during school health education and physical health screening. This must be started immediately because we need to avoid the development of existing cancers where patients will need to seek specialized cancer treatment facilities that are non-existent in these regions. In addition, hospitals need to take a step further and start undergoing registration of cancer prevalence and incidence cases beginning at the regional level. Through the hospital census, countries will be able to determine the magnitude of the cancer burden. Moreover, countries with professionals and researchers with advanced cancer research, education, and training also need to contribute through international cooperation.

Guo X.,Seoul National University | Guo X.,University of Electronic Science and Technology of China
Journal of Biophotonics | Year: 2012

Optical Surface plasmon resonance (SPR) biosensors represent the most advanced and developed optical label-free biosensor technology. Optical SPR biosensors are a powerful detection and analysis tool that has vast applications in environmental protection, biotechnology, medical diagnostics, drug screening, food safety and security. This article reviews the recent development of SPR biosensor techniques, including bulk SPR and localized SPR (LSPR) biosensors, for detecting interactions between an analyte of interest in solution and a biomolecular recognition. The concepts of bulk and localized SPs and the working principles of both sensing techniques are introduced. Major sensing advances on biorecognition elements, measurement formats, and sensing platforms are presented. Finally, the discussions on both biosensor techniques as well as comparison of both SPR sensing techniques are made. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lee H.S.,Seoul National University
Histology and Histopathology | Year: 2012

Transforming growth factor-β (TGF-β) is a key regulator of extracellular matrix (ECM), and may mediate the development of glomerulosclerosis with accumulation of mesangial matrix. Mesangial cells secrete TGF-β in response to common in vitro fibrogenic stimuli. Yet mesangial immunostaining for active TGFβ1 is frequently negative in chronic glomerular disease. TGF-β is rather expressed and/or activated by podocytes in both mesangial and podocyte diseases. Activated TGF-β/Smad signaling by podocytes may induce connective tissue growth factor (CTGF or CCN2) and vascular endothelial growth factor (VEGF) expression. Podocyte CTGF seems to have paracrine effects on mesangial cells to stimulate CTGF expression. CTGF appears to stimulate the fibronectin-matrix assembly via enhanced cell-surface expression of α5β1 integrin in the mesangium of diseased glomeruli. Podocyte VEGF-A overexpression also seems to play a paracrine role on mesangial cells to upregulate VEGF/VEGF receptor systems and to overproduce matrix proteins. Thus, paracrine CTGF and VEGF may contribute to mesangial matrix accumulation in chronic glomerular disease, culminating in the development of glomerulosclerosis. Together, these data bring new mechanistic insights into our understanding of the pathogenic role of TGF-β induced CTGF and VEGF in mesangial matrix expansion in chronic progressive glomerular disease.

Krefl D.,Seoul National University
Journal of High Energy Physics | Year: 2014

Abstract: The Nekrasov-Shatashvili limit of β-ensembles with polynomial potential and N =2 supersymmetric gauge theories in the Ω-background is intimately related to complex one-dimensional quantum mechanics. Multi-instanton corrections in quantum mechanics, inferable from exact quantization conditions, imply additional non-perturbative corrections to the Nekrasov-Shatashvili free energies. Besides filling some of the gaps in previous derivations, we present analytic expressions for such additional non-perturbative corrections in the case of SU(2) gauge theory expanded at strong coupling. In contrast, at weak coupling these additional non-perturbative corrections appear to be negligible. © 2014, The Author(s).

OBJECTIVE: To evaluate the in vitro and in vivo effects of escin on human castration-resistant prostate cancer (CRPC) cells, PC-3 and DU-145.MATERIALS AND METHODS: The inhibition of cell proliferation and its mechanism were assessed through a cytotoxicity assay, flow cytometry, and Western blot. The in vivo efficacy of escin in CRPC cells was assessed using a xenograft tumor model subcutaneously established in BALB/c nude mice.RESULTS: The treatment with escin significantly reduced cell viability of CRPC cells in a dose- and time-dependent manner. Escin induced apoptosis in a time-dependent manner, which was accompanied by increases in pro-apoptotic (BCL-2 associated X protein, cleaved-caspase3, and cleaved-poly [adenosine diphosphate-ribose] polymerase) proteins and decreases in antiapoptotic (X-linked inhibitor of apoptosis protein, cellular inhibitor of apoptosis protein-1, cellular inhibitor of apoptosis protein-2B-cell leukemia/lymphoma-2, and B-cell lymphoma-extra large) proteins. Escin induced G2/M-phase cell cycle arrest and thus led to a significant decrease in the expression of cyclinB1 and its activating partner cyclin-dependent kinase 1, with the concomitant induction of p21. In addition, escin significantly inhibited the growth of CRPC cells in xenograft models.CONCLUSION: The results show that escin induced cytotoxic effects on CRPC cells through the induction of apoptosis and G2/M cell cycle arrest, indicating it may be a novel therapeutic agent for CRPC. Copyright © 2014 Elsevier Inc. All rights reserved.

Ryoo N.K.,Seoul National University
Korean journal of ophthalmology : KJO | Year: 2013

To describe three cases of neovascular glaucoma (NVG) where iris or angle neovascularization regressed remarkably after subconjunctival bevacizumab injections used as the initial treatment before pan retinal photocoagulation (PRP) and/or filtering surgery. Three consecutive NVG patients whose intraocular pressure (IOP) was not controlled with maximal medication were offered an off-label subconjunctival injection of bevacizumab (2.5-3.75 mg/0.1-0.15 mL, Avastin). Bevacizumab was injected into the subconjunctival space close to the corneal limbus in two or three quadrants using a 26-gauge needle. Serial anterior segment photographs were taken before and after the injection. Following subconjunctival injection of bevacizumab, iris or angle neovascularization regressed rapidly within several days. Such regression was accompanied by lowering of IOP in all three cases. The patients underwent subsequent PRP and/or filtering surgery, and the IOP was further stabilized. Our cases demonstrate that subconjunctival bevacizumab injection can be potentially useful as an initial treatment in NVG patients before laser or surgical treatment.

Song Y.,Catholic University of Korea | Joung H.,Seoul National University
Nutrition, Metabolism and Cardiovascular Diseases | Year: 2012

Background and aims: Using national data, we explored the relationship between dietary patterns and metabolic abnormalities to address how the traditional Korean diet, high in carbohydrate and low in animal fat with plenty of plant foods, has influenced metabolic abnormalities in the adult population. Methods and results: We examined cross-sectional associations between dietary patterns and the risk of metabolic abnormalities in 4,730 subjects aged 20 years or more using both health and dietary data from the 2005 Korean National Health and Nutrition Examination survey. Three evident dietary patterns were derived by cluster analysis: 'Traditional' (50.3% of total population), 'Meat and Alcohol, (15.8%) and 'Korean Healthy' (33.9%). The 'Traditional' group was characterised by high consumptions of rice and kimchi, while the 'Korean healthy' group ate a modified Korean-style diet with various foods such as noodles, bread, eggs and milk, and the 'Meat and Alcohol' group had high consumptions of processed meat and alcohol. Compared with the 'Traditional' pattern, the 'Meat and Alcohol' pattern was associated with a 33% increased risk of having elevated blood glucose, a 21% increased risk of having elevated serum triglycerides and a 21% increased risk of having elevated blood pressure. However, the 'Traditional' pattern showed a 23% increased risk of having low high density lipoprotein (HDL)-cholesterol compared with the other two patterns by logistics analysis. Conclusions: Fifty percent of the Korean adult population continues to follow a traditional dietary pattern, having beneficial effects with respect to some metabolic abnormalities. However, the high prevalence of low HDL-cholesterol, attributable to a high-carbohydrate diet, should be considered. © 2010 Elsevier B.V.

Yang J.J.,Seoul National University
Clinics in orthopedic surgery | Year: 2011

The purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications. Thirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as ≥ a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being ≥ 2 mm in the interspinous distance on the flexion-extension lateral radiographs. The anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 ± 1.46 mm and 0.81 ± 1.27 mm, respectively. Subsidence ≥ 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001). Anterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention for avoiding nonunion.

Choi B.I.,Seoul National University
Oncology | Year: 2010

A variety of imaging modalities, including ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine, and angiography, are currently used in evaluating patients with chronic liver disease and suspected hepatocellular carcinoma (HCC). Further technological advancement will undoubtedly have a major impact on liver tumor imaging. Increased speed of data acquisition and consequently shorter scan times in CT and MRI show further improvement in resolution by further reducing motion artifacts. Development of new contrast materials for liver tumor imaging in US and MRI improve tumor detection and characterization by increasing the contrast resolution. Currently available advanced US techniques in the evaluation of HCC are various harmonic imaging techniques with contrast agents, volume imaging, and recently, US elastography, that has been developing and might play a role in characterizing liver nodules in the future. The latest advance in CT is the multidetector (MD) CT scanner where a 256- or 320-detector CT was introduced. Recent studies describe the high sensitivity of double arterial phase imaging in hepatic tumor detection and the usefulness of CT angiography by using MD CT in a detailed assessment of hepatic arterial anatomy using a three-dimensional dataset. In addition, perfusion CT imaging is also being developed and can be used for the characterization and treatment monitoring of HCC. Dual-energy CT with new technology is also continuously progressing. Advances in MR technology, including hardware and pulse sequence implementation, allow acquisition times to be reduced to the time frame of one breathhold, providing multiphasic dynamic MRI. Functional MRI including diffusion-weighted MRI, MR elastography, and new MR contrast agent with dual function have been investigated for the clinical utility of detection and characterization of HCCs. Functional MRI has a potential to be a promising technique for assessing HCC. Copyright © 2010 S. Karger AG.

Jung K.,Seoul National University
Korean journal of radiology : official journal of the Korean Radiological Society | Year: 2012

The aim of this study was to evaluate the frequency of postoperative biliary stricture and its risk factors in patients undergoing surgery for type I choledochal cyst. A total of 35 patients with type I choledochal cyst underwent laparoscopic cyst excision and Roux-en-Y hepaticojejunostomy between August 2004 and August 2011. Their medical records and radiologic images (including endoscopic retrograde cholangiopancreatography, magnetic resonance cholangiopancreatography, pancreatobiliary computed tomography, or ultrasound) were retrospectively analyzed to evaluate the frequency of postoperative biliary stricture and its risk factors. Postoperative biliary stricture was found in 10 (28.6%) of 35 patients. It developed more frequently in patients with type Ia choledochal cyst (53.8%, 7 of 13 patients) than in patients with type Ic choledochal cyst (13.6%, 3 of 22 patients), which was statistically significant (p = 0.011). There were no significant associations between other factors and postoperative biliary stricture. Type Ia is a risk factor of postoperative anastomotic stricture. Therefore, preoperative radiologic subclassification of type Ia and Ic may be useful in predicting postoperative outcomes of choledochal cysts.

An B.-K.,Catholic University of Korea | Gierschner J.,IMDEA Madrid Institute for Advanced Studies | Park S.Y.,Seoul National University
Accounts of Chemical Research | Year: 2012

π-Conjugated organic molecules represent an attractive platform for the design and fabrication of a wide range of nano- and microstructures for use in organic optoelectronics. The desirable optical and electrical properties of π-conjugated molecules for these applications depend on their primary molecular structure and their intermolecular interactions such as molecular packing or ordering in the condensed states. Because of the difficulty in satisfying these rigorous structural requirements for photoluminescence and charge transport, the development of novel high-performance π-conjugated systems for nano-optoelectronics has remained a challenge.This Account describes our recent discovery of a novel class of self-assembling π-conjugated organic molecules with a built-in molecular elastic twist. These molecules consist of a cyano-substituted stilbenic π-conjugated backbone and various terminal functional groups, and they offer excellent optical, electrical, and self-assembly properties for use in various nano-optoelectronic devices. The characteristic "twist elasticity" behavior of these molecules occurs in response to molecular interactions. These large torsional or conformational changes in the cyanostilbene backbone play an important role in achieving favorable intermolecular interactions that lead to both high photoluminescence and good charge carrier mobility in self-assembled nanostructures.Conventional π-conjugated molecules in the solid state typically show concentration (aggregation) fluorescence quenching. Initially, we describe the unique photoluminescence properties, aggregation-induced enhanced emission (AIEE), of these new cyanostilbene derivatives that elegantly circumvent these problems. These elastic twist π-conjugated backbones serve as versatile scaffolds for the preparation of well-defined patterned nanosized architectures through facile self-assembly processes. We discuss in particular detail the preparation of 1D nanowire structures through programmed self-assembly.This Account describes the importance of utilizing AIEE effects to explore optical device applications, such as organic semiconducting lasers (OSLs), optical memory, and sensors. We demonstrate the rich electronic properties, including the electrical conductivity, field-effect carrier mobility, and electroluminescence of highly crystalline 1D nanowire and coaxial donor-acceptor nanocable structures composed of elastic twist π-conjugated molecules. The electronic properties were measured using various techniques, including current-voltage (I-V), conducting-probe atomic force microscopy (CP-AFM), and space-charge-limited- current (SCLC) measurements. We prepared and characterized several electronic device structures, including organic field-effect transistors (OFETs) and organic light-emitting field-effect transistors (OLETs). © 2011 American Chemical Society.

Cho S.C.,Seoul National University
Korean journal of ophthalmology : KJO | Year: 2013

To investigate the morphologic changes in the outer retina of patients with cone dystrophy, using spectral-domain optical coherence tomography (SD-OCT). The medical records of 15 cone dystrophy patients examined from January 2007 to January 2012 were reviewed retrospectively. All patients underwent ophthalmic evaluation including best-corrected visual acuity (BCVA), color vision testing, fundus examination, full-field standard electroretinography (ERG), multifocal (mf) ERG, and SD-OCT. Qualitative and quantitative SD-OCT data and ERG responses were analyzed and compared among the patient categories and the normal control group. There were 4 major categories of SD-OCT findings, based on the status of the ellipsoid portion of the photoreceptor inner segment (ISe), outer segment (OS) contact cylinder, and retinal pigment epithelium (RPE) layer. Category 0 showed no structural abnormalities. Category 1 showed foveal ISe loss and obscurity of the border between the ISe band and the external limiting membrane (ELM). Category 2 showed foveal thinning and focal foveal ISe disruption with an intact ELM. Category 3 showed foveal thickening and perifoveal disruption of the ISe layer. Category 1 to 3 showed OS contact cylinder layer absence and RPE thickening. The patients in category 0 tended to be younger (mean, 10.0 years) than those in categories 1 to 3 (mean, 17.6 years), although this difference was not statistically significant. Category 1 to 3 patients exhibited statistically significant thinning of the central retina and outer nuclear layer and thickening of the RPE layer relative to the category 0 and normal control group. There was a significant correlation between the central foveal thickness and BCVA in the patients with cone dystrophy. ERG and mfERG responses did not differ significantly among the different cone dystrophy categories. The morphologic features of cone dystrophy as revealed by SD-OCT, could be categorized as either normal or 1 of 3 different types of outer retinal changes. The presence of normal retinal structures in young cone dystrophy patients with functional impairment (category 0) indicates that electrophysiologic studies are superior to current imaging modalities for the early diagnosis of cone dystrophy. The characteristic SD-OCT findings in cone dystrophy patients may aid in differential diagnosis and be useful for future research on the pathology of cone dystrophy.

An implicit finite element model was developed to analyze the deformation behavior of low carbon steel during phase transformation. The finite element model was coupled hierarchically with a phase field model that could simulate the kinetics and micro-structural evolution during the austenite-to-ferrite transformation of low carbon steel. Thermo-elastic-plastic constitutive equations for each phase were adopted to confirm the transformation plasticity due to the weaker phase yielding that was proposed by Greenwood and Johnson. From the simulations under various possible plastic properties of each phase, a more quantitative understanding of the origin of transformation plasticity was attempted by a comparison with the experimental observation.

Lee S.,Seoul National University
Computational Statistics and Data Analysis | Year: 2013

In this paper, we propose a goodness of fit test based on maximum entropy. As an extension of the result on the simple versus simple hypothesis case handled by Lee et al. (2011), a composite hypothesis case is taken into consideration. To eliminate the parameter estimation effect, we apply the Khmaladze transformation for the empirical process and obtain the asymptotic distribution of the proposed test. The performance of the test is investigated through Monte Carlo simulations. © 2012 Elsevier B.V. All rights reserved.

Lee J.H.,Seoul National University
Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology | Year: 2013

The plasmonic properties of metallic nanoparticles (NPs) such as Au and Ag NPs and the plasmonic coupling between them are of enormous interest for their strong and controllable optical signal enhancement and manipulation capabilities. The strong optical properties of these plasmonic structures are promising for various biosensing applications, but the widespread use of these structures is limited largely due to the absence of high-yield synthetic method for targeted nanoprobes with nanometer precision and the poor understanding of the plasmonics of these structures. DNA is a promising material that can be used as both specific biorecognition and versatile synthetic template in forming and controlling plasmonic nanostructures and their aggregations. In this article, we provide an overview and perspective of recent advances in the use of DNA-tailored plasmonic nanostructures in biosensing applications. Copyright © 2012 Wiley Periodicals, Inc.

Park Y.S.,Seoul National University
The International journal of oral & maxillofacial implants | Year: 2011

This study attempted to establish three-dimensional average curves of the gingival line of maxillary teeth using reconstructed virtual models to utilize as guides for dental implant restorations. Virtual models from 100 full-mouth dental stone cast sets were prepared with a three-dimensional scanner and special reconstruction software. Marginal gingival lines were defined by transforming the boundary points to the NURBS (nonuniform rational B-spline) curve. Using an iterative closest point algorithm, the sample models were aligned and the gingival curves were isolated. Each curve was tessellated by 200 points using a uniform interval. The 200 tessellated points of each sample model were averaged according to the index of each model. In a pilot experiment, regression and fitting analysis of one obtained average curve was performed to depict it as mathematical formulae. The three-dimensional average curves of six maxillary anterior teeth, two maxillary right premolars, and a maxillary right first molar were obtained, and their dimensions were measured. Average curves of the gingival lines of young people were investigated. It is proposed that dentists apply these data to implant platforms or abutment designs to achieve ideal esthetics. The curves obtained in the present study may be incorporated as a basis for implant component design to improve the biologic nature and related esthetics of restorations.

Goo J.M.,Seoul National University
Korean Journal of Radiology | Year: 2011

As the detection and characterization of lung nodules are of paramount importance in thoracic radiology, various tools for making a computer-aided diagnosis (CAD) have been developed to improve the diagnostic performance of radiologists in clinical practice. Numerous studies over the years have shown that the CAD system can effectively help readers identify more nodules. Moreover, nodule malignancy and the response of malignant lung tumors to treatment can also be assessed using nodule volumetry. CAD also has the potential to objectively analyze the morphology of nodules and enhance the workflow during the assessment of follow-up studies. Therefore, understanding the current status and limitations of CAD for evaluating lung nodules is essential to effectively apply CAD in clinical practice.

Lee S.K.,Seoul National University
Solid State Nuclear Magnetic Resonance | Year: 2010

Revealing the structure of oxide glasses at high pressure remains a fundamental yet difficult problem in modern physical and chemical sciences. The recent advances in solid-state NMR techniques used for quadrupolar nuclides offer a considerably improved resolution of atomic sites, unveiling previously unknown structural details of oxides glasses at high pressure. Here, we present an overview of the recent progress and insights by high-resolution multi-nuclear triple quantum magic angle spinning (3QMAS) NMR into pressure-induced changes in coordination number, connectivity, and topological disorder in oxide glasses quenched from melts at high pressure. 11B and 27Al 3QMAS NMR studies of oxide glasses show that the formation of highly coordinated Al ([5,6]Al) and four coordinated [4]B are prevalent at high pressure up to 8 GPa. The formation of oxygen clusters linking these highly coordinated framework units and Si (e.g., [5,6]AlO[4]Si, [5,6]SiO[4]Si, and NaO[5,6]Si) is observed in the 17O NMR spectra at higher pressure, leading to an overall increase in the degree of polymerization with pressure. 23Na MAS NMR spectra of diverse oxide glasses at high pressure and high magnetic field also indicate that the NaO bond distance may decrease with pressure. Pressure-induced changes in structurally relevant NMR parameters such as the 17O quadrupolar coupling product (Pq) for the SiOSi cluster and 27Al Pq for Al sites in oxide glasses indicate the occurrence of pressure-induced reductions in the SiOSi angle and an increase in the AlO bond length distribution with pressure, indicating an increase in the overall topological disorder in oxide glasses with pressure. All the pressure-induced changes in structure and topology are characterized by strong composition dependence. These experimental results highlight a new opportunity to investigate the molecular structures of silicate melts at high pressure and reveal connections between the microscopic signatures of anomalous and non-linear changes in the macroscopic properties of the corresponding liquids. While many challenges still remain in the synthesis of oxide glasses with wider range of melt composition at higher pressure above 12 GPa, recent progress in enhancement of sensitivity and resolution in the solid state NMR hold strong promise for study exploring additional details of connectivity among quadrupolar nuclides and medium-range order of the more complex, multi-components glasses at high pressure. © 2010 Elsevier Inc.All rights reserved.

Kim D.H.,Yonsei University | Kim W.T.,Cheongju University | Park E.S.,Seoul National University | Mattern N.,Leibniz Institute for Solid State and Materials Research | And 2 more authors.
Progress in Materials Science | Year: 2013

Phase separation phenomena in metallic glass systems are reviewed. First, a brief introduction to the enhanced glass forming ability and the phase separation in metallic glass systems is given. Nano-scale phase separation observed in frozen-in glass is discussed in marginal glass formers such as Pd-, Fe, Al-base metallic glass systems as well as in bulk glass formers in Cu-, Zr- and Mg-base metallic glass systems. Since retention of glass forming ability is essential in phase separating glasses, thermodynamic and kinetic conditions for enhanced glass forming ability is introduced. Several thermodynamic aspects for decomposition by liquid-liquid phase separation which include stability conditions, decomposition in the multicomponent system, types of miscibility gap, calculation of bimodal and spinodal curves are introduced as a background for design of metallic glasses phase separating in the liquid state. The main mechanisms for phase separation are nucleation and growth mechanism and spinodal decomposition mechanism. The metallic glass systems which include an atom pair with large positive enthalpy of mixing decompose by liquid-liquid phase separation separate in the liquid state, forming two typical types of microstructure: droplet or interconnected type microstructures depending on the mechanism of phase separation. By calculation of the tile line, it is possible to design phase separating metallic glasses with high glass forming ability. Eventually, bulk-type phase separating metallic glasses with mm scale can be synthesized. Moreover, if there is a group of three atoms with large positive enthalpy of mixing in the liquid state in the multicomponent system, occurrence of three phase separation in the liquid state is possible. There are several parameters affecting the microstructure evolution during phase separation, which includes glass transition and critical temperatures, shape of bimodal and spinodal curves and quenching conditions. Phase separation in the solid state of the frozen-in glasses can give a clue on the phase separation prior to crystallization or direct nanocrystallization from the amorphous matrix. The amplitude of the composition fluctuation with a fixed wavelength can grow by heating in the solid state, if the spinodal decomposition. Finally, some advantages of phase separation phenomena in metallic glass systems are highlighted. © 2013 Elsevier Ltd. All rights reserved.

Histone deacetylase (HDAC) inhibitors (HDIs) are promising anticancer therapies and have been clinically used for the treatment of hematological malignancy. However, their efficacy in solid tumors is marginal and drug resistance hampers their further clinical utility. To develop novel strategies for the HDI-based anticancer therapeutics in non-small cell lung cancer (NSCLC), in the present study, we investigated the mechanisms underlying resistance to HDI treatment in NSCLC cells. We show the STAT3-mediated IGF2/IGF-1R signaling cascade as a key modulator for both acquired and primary HDI resistance. The treatment with HDI upregulated IGF2 transcription in NSCLC cells carrying intrinsic or acquired drug resistance via direct binding of STAT3 in IGF2 P3 and P4 promoters. Acetylated STAT3 emerged upon HDAC inhibition was protected from the proteasome-mediated degradation of STAT3 and functioned as a direct transcription factor for IGF2 expression. Genomic or pharmacological strategies targeting STAT3 diminished the HDI-induced IGF2 mRNA expression and overcame the resistance to HDI treatment in HDI-resistant NSCLC- or patient-derived tumor xenograft models. These findings provide new insights into the role of acetylated STAT3-mediated activation of IGF2 transcription in HDI resistance, suggesting IGF2 or STAT3 as novel targets to overcome HDI resistance in NSCLC.Oncogene advance online publication, 18 April 2016; doi:10.1038/onc.2016.92. © 2016 Macmillan Publishers Limited

Kim J.-E.,Seoul National University
Oncogene | Year: 2016

The downstream events and target genes of p53 in the process of senescence are not fully understood. Here, we report a novel function of the forkhead transcription factor Foxp3, which is a key player in mediating T-cell inhibitory functions, in p53-mediated cellular senescence. The overexpression of Foxp3 in mouse embryonic fibroblasts (MEFs) accelerates senescence, whereas Foxp3 knockdown leads to escape from p53-mediated senescence in p53-expressing MEFs. Consistent with these results, Foxp3 expression resulted in the induction of senescence in epithelial cancer cells, including MCF7 and HCT116 cells. Foxp3 overexpression also increased the intracellular levels of reactive oxygen species (ROS). The ROS inhibitor N-acetyl-l-cysteine rescued cells from Foxp3-expression-induced senescence. Furthermore, the elevated ROS levels that accompanied Foxp3 overexpression were paralleled by an increase in p21 expression. Knockdown of p21 in Foxp3-expressing MEFs abrogated the Foxp3-dependent increase in ROS levels, indicating that Foxp3 acts through the induction of p21 and the subsequent ROS elevation to trigger senescence. Collectively, these results suggest that Foxp3 is a downstream target of p53 that is sufficient to induce p21 expression, ROS production and p53-mediated senescence.Oncogene advance online publication, 30 May 2016; doi:10.1038/onc.2016.193. © 2016 Macmillan Publishers Limited

Lee W.-J.,Samsung | Sul S.-K.,Seoul National University
IEEE Transactions on Industry Applications | Year: 2014

In conventional motor drive systems using pulsewidth modulation (PWM) inverters, large electrolytic capacitors are used for stabilization of the dc-link voltage. Since the electrolytic capacitors are bulky and reduce reliability of the system due to short lifetime, there have been many efforts to eliminate or reduce the electrolytic capacitors in the motor drive system. However, the PWM inverter with reduced dc-link capacitor has a problem that the dc-link voltage is less stable compared to the conventional inverter because the capability of storing energy is also reduced. In this paper, a dc-link voltage stabilization algorithm using an active damping is proposed so that the dc-link voltage can be stabilized with reduced dc-link capacitor. To achieve load-/source-independent stabilization, a source state estimator which estimates both source voltage and current is also proposed. The fluctuation of the dc-link voltage due to a step load change can be also suppressed under the tolerance range using the estimated source current. The effectiveness of the proposed methods is evaluated by experimental results. © 1972-2012 IEEE.

Bang Y.-J.,Seoul National University
Journal of Clinical Gastroenterology | Year: 2012

In the past, patients with advanced or metastatic gastric or gastroesophageal junction cancer have had few treatment options and generally poor survival rates. The human epidermal growth factor receptor 2 (HER2) has been identified as a potential therapeutic target because of its overexpression or gene amplification in 6% to 35% of gastric or gastroesophageal junction cancers, although the methods of assessment and prognostic value of HER2 have been subject to debate. The phase III Trastuzumab for Gastric Cancer (ToGA) trial showed that adding the HER2-targeted humanized monoclonal antibody trastuzumab to chemotherapy significantly improves survival without negatively impacting quality of life in patients with advanced gastric or gastroesophageal junction cancer. As a result, trastuzumab is now the sole HER2-targeted therapy approved in several countries for this indication. The ToGA trial also demonstrated that patients who expressed higher levels of HER2 (determined by immunohistochemical screening) received the greatest benefit from trastuzumab therapy. This finding underlines the importance of accurate HER2 testing. Because of the unique characteristics of gastric cancer, a new gastric cancer-specific scoring system for HER2 expression was proposed during the ToGA trial. The aim of this review is to inform the gastroenterologist of the potential role of HER2-targeted therapy, to discuss the importance of accurate and reliable HER2 testing, and to discuss ongoing studies with HER2-targeted therapies that may have an impact on the future treatment of HER2-positive gastric cancer. Copyright © 2012 by Lippincott Williams & Wilkins.

An S.-I.,Yonsei University | Choi J.,Seoul National University
Climate Dynamics | Year: 2014

Using the Paleoclimate Modeling Inter-comparison Project Phase 2 and 3 (PMIP2 and PMIP3), we investigated the tropical Pacific climate state, annual cycle, and El Niño-Southern Oscillation (ENSO) during the mid-Holocene period (6,000 years before present; 6 ka run). When the 6 ka run was compared to the control run (0 ka run), the reduced sea surface temperature (SST) and the reduced precipitation due to the basin-wide cooling, and the intensified cross-equatorial surface winds due to the hemispheric discrepancy of the surface cooling over the tropical Pacific were commonly observed in both the PMIP2 and PMIP3, but changes were more dominant in the PMIP3. The annual cycle of SST was weaker over the equatorial eastern Pacific, because of the orbital forcing change and the deepening mixed layer, while it was stronger over the equatorial western pacific in both the PMIP2 and PMIP3. The stronger annual cycle of the equatorial western Pacific SST was accompanied by the intensified annual cycle of the zonal surface wind, which dominated in the PMIP3 in particular. The ENSO activity in the 6 ka run was significantly suppressed in the PMIP2, but marginally reduced in the PMIP3. In general, the weakened air-sea coupling associated with basin-wide cooling, reduced precipitation, and a hemispheric contrast in the climate state led to the suppression of ENSO activity, and the weakening of the annual cycle over the tropical eastern Pacific might lead to the intensification of ENSO through the frequency entrainment. Therefore, the two opposite effects are slightly compensated for by each other, which results in a small reduction in the ENSO activity during the 6 ka in the PMIP3. On the whole, in PMIP2/PMIP3, the variability of canonical (or conventional) El Niño tends to be reduced during 6 ka, while that of CP/Modoki El Niño tends to be intensified. © 2013 Springer-Verlag Berlin Heidelberg.

Han T.-H.,Pohang University of Science and Technology | Lee Y.,Sungkyunkwan University | Choi M.-R.,Pohang University of Science and Technology | Woo S.-H.,Pohang University of Science and Technology | And 4 more authors.
Nature Photonics | Year: 2012

Although graphene films have a strong potential to replace indium tin oxide anodes in organic light-emitting diodes (OLEDs), to date, the luminous efficiency of OLEDs with graphene anodes has been limited by a lack of efficient methods to improve the low work function and reduce the sheet resistance of graphene films to the levels required for electrodes1-4. Here, we fabricate flexible OLEDs by modifying the graphene anode to have a high work function and low sheet resistance, and thus achieve extremely high luminous efficiencies (37.2 lm W-1 in fluorescent OLEDs, 102.7 lm W -1 in phosphorescent OLEDs), which are significantly higher than those of optimized devices with an indium tin oxide anode (24.1 lm W -1 in fluorescent OLEDs, 85.6 lm W-1 in phosphorescent OLEDs). We also fabricate flexible white OLED lighting devices using the graphene anode. These results demonstrate the great potential of graphene anodes for use in a wide variety of high-performance flexible organic optoelectronics. © 2012 Macmillan Publishers Limited. All rights reserved.

Kye S.-H.,Seoul National University
Reports on Mathematical Physics | Year: 2012

It is well known that the support of an optimal decomposable entanglement witness is completely entangled. We add two more necessary conditions for the optimality: The orthogonal complement of the support must have a nonzero product vector; another one will be given in terms of related faces of a convex cone. With these necessary conditions, we show that there exist examples of nonoptimal decomposable entanglement witnesses which are the partial transposes of positive semi-definite matrices supported on completely entangled spaces, whenever both of the local dimensions are greater than or equal to three. © 2012 Polish Scientific Publishers.

To compare the clinical outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size grafts in patients with keratoconus. Medical records of 16 eyes from 15 patients treated from June 2005 through April 2011 were retrospectively reviewed. Patients with contact lens intolerance or who were poor candidates for contact lens fitting due to advanced cone underwent keratoplasty. The transplantations consisted of 11 DALK and 5 PKP with same-size grafting for keratoconus. Best-corrected visual acuity (BCVA), refractive error, corneal topographic profiling, and clinical course were compared between DALK and PKP groups. The follow-up period was 30 ± 17 months in the DALK group and 45 ± 20 months in the PKP group (p = 0.145). At final follow-up, the DALK and PKP groups achieved a BCVA (logarithm of the minimum angle of resolution) of 0.34 and 0.52, respectively (p = 0.980). Postoperative refractive error and mean simulated keratometric index showed myopic astigmatism in both groups without any statistical difference. Corneal irregularity index measured at 5 mm in the DALK group was less than that of the PKP group at 1-year follow-up (p = 0.021); however, at final follow-up, there was no longer a statistically significant difference. Endothelial cell counts were lower in the PKP group than in the DALK group at final follow-up (p = 0.021). The optical outcomes of DALK with same-size grafts for keratoconus are comparable to those of PKP. Endothelial cell counts are more stable in DALK compared to PKP.

Oh S.W.,Seoul National University
Journal of women's health (2002) | Year: 2010

The association between hormone therapy (HT) use and lung cancer risk is inconsistent in epidemiological studies. This meta-analysis was conducted to examine the association between HT and lung cancer risk. We searched MEDLINE (PubMed), EMBASE, and the Cochrane Library in April 2008. All articles searched were independently reviewed and selected by two evaluators according to predetermined inclusion and exclusion criteria. We included a total of 11 studies (8 case-control studies and 3 prospective cohort studies), involving a total of 220,599 participants. When all studies were pooled, the odds ratio (OR) of HT use for lung cancer risk was 0.87 (95% confidence interval (CI) 0.74-1.02). In subgroup meta-analyses, there was no association among cohort studies (relative risk (RR) 1.01; 95% CI 0.74-1.38), while there was a significant association between HT use and lung cancer risk among case-control studies (OR 0.81; 95% CI 0.68-0.97) based on a random-effects model. No significant association between HT use and lung cancer risk was observed in most of the subgroup meta-analyses by methodological quality of study, type of HT use, duration of HT use, and histology of lung cancer, while significant protective effects were observed among former and never smokers except for current smokers. However, cumulative meta-analyses based on year of publication showed a distinct trend toward a protective effect of HT use on lung cancer risk in the recent studies. Overall, the findings of this meta-analysis do not support the hypothesis that there is a link between HT use and lung cancer risk. Our findings should be evaluated in further prospective cohort studies.

Zhang F.,University of Pennsylvania | Min H.,Seoul National University | MacDonald A.H.,University of Texas at Austin
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We use a perturbative renormalization group approach with short-range continuum model interactions to analyze the competition between isotropic gapped and anisotropic gapless ordered states in bilayer graphene, commenting specifically on the role of exchange and on the importance of spin and valley flavor degeneracy. By comparing the divergences of the corresponding susceptibilities, we conclude that this approach predicts gapped states for flavor numbers N=1,2,4. We comment briefly on other approaches which can be used to shed light on the bilayer ground state and on the related ground state of chiral (ABC) trilayers. © 2012 American Physical Society.

Background: Young and unmarried women have not been a target group for cervical cancer prevention in Korea. No previous studies have investigated the awareness of Pap testing, the intention to undergo Pap testing, or the factors associated with that intention, in this group of women. This information would be useful for an expansion in the focus of primary cervical cancer prevention. This study aimed to compare the awareness of Pap testing between groups of unmarried university students in Korea, and to investigate the factors associated with the intention to undergo Pap testing, by level of sexual experience. Methods: A total of 475 unmarried university students who had never undergone a Pap test completed a web-based survey. Differences in awareness of the importance of the Pap test, confidence in Pap testing, intention to undergo the test, attitudes, subjective norms, perceived control, stigma, and shame by level of sexual experience were analysed using independent t-tests. Associations between measurement variables and intention to undergo Pap testing were analysed using correlation analysis. Variables yielding significant associations (p < 0.05) were included in a stepwise multiple regression model of intention to undergo Pap testing. Results: Most participants perceived that the need for regular Pap testing was less important (score, 77.76) than other methods of cervical cancer prevention. They were not confident that is was an effective method of cervical cancer prevention for themselves (score, 59.56). There were differences in confidence in Pap testing and in the factors associated with intention to undergo Pap testing between sexually experienced and sexually inexperienced students. Regardless of level of sexual experience, the subjective norm was the most important predictor of intention to undergo Pap testing. Conclusions: There was a low level of Pap screening awareness among the students. The factors associated with intention to undergo Pap testing differed by level of sexual experience. Social influence was an important factor that could be used to increase the intention to receive a Pap test in the university student population. Strategies to increase the intention to undergo Pap screening should be introduced and should be adapted to the level of sexual experience. © 2014 Kim; licensee BioMed Central Ltd.

Kim J.-G.,Seoul National University | Kuby M.,Arizona State University
Computers and Operations Research | Year: 2013

In the early stages of development, alternative-fuel vehicles will tend to have shorter driving ranges than conventional vehicles, and the availability of stations will be limited. Given these conditions, it is important to consider the willingness of drivers to deviate to some extent from their shortest paths in order to refuel their vehicles and complete their trips. Previously, we proposed the deviation-flow refueling location model (DFRLM) for locating a given number of refueling facilities to maximize the total alternative-fuel vehicle flows that can be refueled by drivers traveling on or deviating from their shortest paths. On a real-world problem, however, the large number of possible deviations from each path and of combinations of facilities that can cover each path would make it extremely difficult to generate and solve the mixed-integer formulation. This paper develops heuristic algorithms for the DFRLM that overcome this difficulty through network transformation. Specifically, a greedy heuristic constructs and edits an artificial feasible network in which each node represents a station, origin, or destination, and each arc represents a feasible path between two nodes given the assumed driving range of vehicles. At each step of the greedy and greedy-substitution algorithms, the feasible network is edited and a shortest path algorithm is run, which determines whether each origin-destination round trip can be completed. This method allows any possible detour to be taken (up to some user-defined maximum) while also ensuring that drivers take the smallest possible detour. Computational experiments on a simple network and a real-world network for Florida show the heuristics to be efficient in solving the problems. Comparisons between the results of the DFRLM and the FRLM indicate that taking driver deviations into account in the model can have a significant effect on the locations chosen and demand covered. © 2012 Elsevier Ltd.

To compare the effect of using fibrin glue or 10-0 nylon sutures on the clinical outcome of patients undergoing pterygium excision and conjunctival autografting. We retrospectively reviewed the medical records of 52 eyes from 46 patients who underwent pterygium excision and conjunctival autografting and were followed up for more than 3 months. The operation duration, postoperative inflammation, complications, and recurrence rates were compared between groups of 20 patients (22 eyes) for whom fibrin glue was used (fibrin glue group) and 26 patients (30 eyes) for whom suturing was performed with 10-0 nylon (suture group) in pterygium excision and conjunctival autografting. The operation duration was 27.71 (5.22) minutes in the fibrin glue group and 43.30 (8.18) minutes in the suture group (p = 0.000). Seven days after the operation, the fibrin glue group showed milder conjunctival inflammation than the suture group (p = 0.000). Postoperative complications and corneal recurrence rates were not statistically different between the two groups. The use of fibrin glue in pterygium excision with conjunctival autografting is likely to be a more effective, safer procedure than suturing.

Kim S.-W.,Gyeongsang National University | Rhee C.-S.,Seoul National University
Current Opinion in Otolaryngology and Head and Neck Surgery | Year: 2012

Purpose of review: Although numerous surgical techniques have been introduced thus far in order to achieve the surgical closure of nasal septal perforation, the repair of nasal septal perforation is still challenging for surgeons and operative techniques are not standardized. Furthermore, predictive factors for successful closure have not been elucidated. This review aimed to investigate predictive factors for complete closure of nasal septal perforation. Recent findings: The size of perforation was the most significant factor for complete closure. Surgical failure occurred more frequently in patients with large perforation (>2 cm) than those with small-to-moderate perforation (≤2 cm). The bilateral coverage over the perforation with vascularized mucosal flap also helped complete closure. Interposition of grafts appeared to assist complete closure, although it was statistically insignificant. Summary: This review provides information for surgeons on how to predict surgical outcomes of the repair of nasal septal perforation and which surgical techniques to choose in order to obtain better results. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Shah N.A.,Bombay Hospital and Research Center | Jain N.P.,Bombay Hospital and Research Center | Jain N.P.,Seoul National University
Journal of Arthroplasty | Year: 2014

Total knee arthroplasty is associated with intense, early post-operative pain. Femoral nerve block is known to provide optimal pain relief but reduces the strength of the quadriceps muscle and associated with the risk of falling. Adductor canal block is almost pure sensory blockade with minimal effect on quadriceps muscle strength. We prospectively randomized 100 patients in two groups' continuous adductor and femoral block group. Ambulation ability (Timed up go, 10-m walk, 30. s chair test), time to active SLR, quadsticks, staircase competency, ambulation distance was significantly better (P value. <. 0.001) in adductor canal group whereas pain scores, opioid consumption showed no significant difference. Adductor canal block provided better ambulation and early functional recovery but without superior analgesia than femoral nerve block post TKA. Level of evidence: Level III, therapeutic study. © 2014 Elsevier Inc.

Jochum F.D.,University of Mainz | Jochum F.D.,Catholic University of Louvain | Theato P.,Seoul National University | Theato P.,TU Hamburg - Harburg
Chemical Society Reviews | Year: 2013

Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness. © 2013 The Royal Society of Chemistry.

Kim D.,Rochester College | Kim D.,Seoul National University | Kim W.R.,Rochester College | Kim H.J.,University of Ulsan | Therneau T.M.,Rochester College
Hepatology | Year: 2013

The clinical and public health significance of nonalcoholic fatty liver disease (NAFLD) is not well established. We investigated the long-term effect of NAFLD on mortality. This analysis utilized the National Health and Nutrition Examination Survey conducted in 1988-1994 and subsequent follow-up data for mortality through December 31, 2006. NAFLD was defined by ultrasonographic detection of hepatic steatosis in the absence of other known liver diseases. The presence and severity of hepatic fibrosis in subjects with NAFLD was determined by the NAFLD fibrosis score (NFS), the aspartate aminotransferase to platelet ratio index (APRI), and FIB-4 score. Of 11,154 participants, 34.0% had NAFLD-the majority (71.7%) had NFS consistent with lack of significant fibrosis (NFS <-1.455), whereas 3.2% had a score indicative of advanced fibrosis (NFS >0.676). After a median follow-up of 14.5 years, NAFLD was not associated with higher mortality (age- and sex-adjusted hazard ratio [HR]: 1.05; 95% confidence interval [CI]: 0.93-1.19). In contrast, there was a progressive increase in mortality with advancing fibrosis scores. Compared to subjects without fibrosis, those with a high probability of advanced fibrosis had a 69% increase in mortality (for NFS: HR, 1.69, 95% CI: 1.09-2.63; for APRI: HR, 1.85, 95% CI: 1.02-3.37; for FIB-4: HR, 1.66, 95% CI: 0.98-2.82) after adjustment for other known predictors of mortality. These increases in mortality were almost entirely from cardiovascular causes (for NFS: HR, 3.46, 95% CI: 1.91-6.25; for APRI: HR, 2.53, 95% CI: 1.33-4.83; for FIB-4: HR, 2.68, 95% CI: 1.44-4.99). Conclusions: Ultrasonography-diagnosed NAFLD is not associated with increased mortality. However, advanced fibrosis, as determined by noninvasive fibrosis marker panels, is a significant predictor of mortality, mainly from cardiovascular causes, independent of other known factors. © 2012 American Association for the Study of Liver Diseases.

Chae C.,Seoul National University
Veterinary Journal | Year: 2012

Porcine circovirus type 2 (PCV2) is the one of the most economically important pathogens of pigs. After postweaning multisystemic wasting syndrome (PMWS) was first identified and reported in western Canada in 1991, it took 13. years for the first commercial PCV2 vaccine to be used under special licence in France and Germany in 2004. Along with PMWS, PCV2 is also associated with a number of diseases and syndromes, collectively referred to as porcine circovirus-associated disease (PCVAD). Currently, five commercial vaccines are available on the international market. Commercial PCV2 vaccines were initially developed to control PMWS, but they are now also used against other PCVAD. This review focuses on (1) the types of commercial vaccines; (2) the criteria of vaccine efficacy; (3) the clinical, virological, immunological and pathological efficacy of the vaccines; and (4) the use of PCV2 vaccines against different clinical manifestations of PCVAD. © 2012 Elsevier Ltd.

Chen D.Y.-K.,Seoul National University | Youn S.W.,Hanyang University
Chemistry - A European Journal | Year: 2012

The recent advent of transition-metal mediated C-H activation is revolutionizing the synthetic field and gradually infusing a "C-H activation mind-set" in both students and practitioners of organic synthesis. As a powerful testament of this emerging synthetic tool, applications of C-H activation in the context of total synthesis of complex natural products are beginning to blossom. Herein, recently completed total syntheses showcasing creative and ingenious incorporation of C-H activation as a strategic manoeuver are compared with their "non-C-H activation" counterparts, illuminating a new paradigm in strategic synthetic design. The total synthesis of natural products has been carried out showcasing the creative and ingenious application of C-H activation in the construction of complex molecular architectures that are compared with their "non-C-H activation" counterparts. These accomplishments stood as true testaments of the growing potential of C-H activation, and further cementing the power of this emerging synthetic technology (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prockop D.J.,Texas A&M University | Oh J.Y.,Seoul National University
Journal of Cellular Biochemistry | Year: 2012

There is currently great interest in the use of mesenchymal stem/stromal cells (MSCs) for the therapy of many diseases of animals and humans. However, we are still left with the serious challenges in explaining the beneficial effects of the cells. Hence, it is essential to work backward from dramatic results obtained in vivo to the cellular and molecular explanations in order to discover the secrets of MSCs. This review will focus on recent data that have changed the paradigms for understanding the therapeutic potentials of MSCs. © 2011 Wiley Periodicals, Inc. © 2011 Wiley Periodicals, Inc.

Kang G.H.,Seoul National University
Korean Journal of Pathology | Year: 2012

Gastric cancers arise through a multistep process characterized by the progressive accumulation of molecular alterations in which genetic and epigenetic mechanisms have been implicated. Gastric cancer is one of the human malignancies in which aberrant promoter CpG island hypermethylation is frequently found. Helicobacter pylori and Epstein-Barr virus, which are known carcinogens for gastric cancer, are closely associated with enhanced hypermethylation of CpG island loci in gastric non-neoplastic epithelial cells and cancer cells, respectively. Aberrant CpG island hypermethylation occurs early in the multistep cascade of gastric carcinogenesis and tends to increase with the step-wise progression of the lesion. Approximately 400 genes that are actively expressed in normal gastric epithelial cells are estimated to be inactivated in gastric cancers as a result of promoter CpG island hypermethylation. In this review, a variety of information is summarized regarding CpG island hypermethylation in gastric cancer. © 2012 The Korean Society of Pathologists/The Korean Society for Cytopathology.

Seo J.K.,Seoul National University
Pediatric Gastroenterology, Hepatology and Nutrition | Year: 2012

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism that results in accumulation of copper primarily in the liver, brain and cornea. Mutations in the WD gene, ATP7B, cause failure of copper excretion from hepatocyte into bile and a defective synthesis of ceruloplasmin. More than 500 mutations are now recognized, scattered throughout the ATP7B gene. Since WD has protean clinical presentations, awareness of WD in clinical practice is important for the early diagnosis and prevention of accumulated copper toxicity. Molecular genetic testing is playing an increasingly important role in the diagnosis of WD in uncertain cases and family screening. Siblings should be screened for WD once an index case has been diagnosed. Discrimination of heterozygotes from asymptomatic patients is essential to avoid inappropriate lifelong therapy for heterozygotes. Genetic testing, either by haplotype analysis or by mutation analysis, is the only definite solution for differentiating heterozygote carriers from affected asymptomatic patients. Routine genetic testing, because of the multitude of documented mutations, has been thought to be impractical until recently. However, genetic testing is now being more actively applied to the diagnosis of WD, particularly in young children in whom conventional biochemical diagnosis has much limitation and only genetic testing is able to confirm WD. Because advancement of modern biochemical technology now allows more rapid, easier, and less expensive mutation detection, direct DNA sequencing could be actively considered as the primary mode of diagnostic investigation rather than a supplementary test to the conventional biochemical tests. This review will focus on the recent advancement of molecular genetics and genetic diagnosis of WD in very young children on the basis of research data of the Seoul National University Children's Hospital and recent literature. © 2014 by The Korean Society of Pediatric Gastroenterology, Hepatology and Nutrition.

Hybrid films of gold nanoparticles and graphene oxides (GOs) were prepared by directly growing gold nanoparticles on supported thin layers of GO films on a glass slide. The gold/GO nanohybrid films were thoroughly investigated using various analytical methods, including Raman spectroscopy and atomic force microscopy. The hybrid film was then applied to laser desorption/ionization (LDI) of small molecules, which enabled mass spectrometric analysis of analytes. After a series of detailed mechanistic studies and systematic investigations, we found that the gold/GO hybrid films serve as a successful LDI platform for small-molecule analysis because of the high desorption efficiency of analytes from the hybrid films without inducing significant fragmentation of analytes. We suggest that the underlying GO films may effectively dissipate excess thermal energy generated by laser irradiation of Au to prevent undesirable analyte fragmentation. © 2012 American Chemical Society.

Choi Y.,Seoul National University
Transplantation | Year: 2014

Living donor hepatectomy is now a well-established surgical procedure. However, a large abdominal incision is still required, which results in a large permanent scar, especially for a right liver graft. This report reviews our techniques of minimally invasive or minimal incisional donor hepatectomy using a transverse incision.Twenty-five living donors underwent right hepatectomy with a transverse incision and 484 donors with a conventional incision between April 2007 and December 2012. Among the donors with a transverse incision, two cases were totally laparoscopic procedures using a hand-port device; 11 cases were laparoscopic-assisted hepatectomy (hybrid technique), and 14 cases were open procedures using a transverse incision without the aid of the laparoscopic technique. Currently, a hybrid method has been exclusively used because of the long operation time and surgical difficulty in totally laparoscopic hepatectomy and the exposure problems for the liver cephalic portion during the open technique using a transverse incision.All donors with a transverse incision were women except for one. Twenty-four of the grafts were right livers without middle hepatic vein (MHV) and one with MHV. The donors' mean BMI was 21.1 kg/m. The median operation time was 355 minutes, and the mean estimated blood loss was 346.1±247.3 mL (range, 70-1200). There was no intraoperative transfusion. These donors had 29 cases of grade I [14 pleural effusions (56%), 11 abdominal fluid collections (44%), 3 atelectasis (12%), 1bile leak (4%)], 1 case of grade II (1 pneumothorax) and two cases of grade III complications; two interventions were needed because of abdominal fluid collections by Clavien-Dindo classification. Meanwhile, donors with a conventional big incision, which included the Mercedes-Benz incision or an inverted L-shaped incision, had 433 cases of grade I, 19 cases of grade II and 18 cases of grade III complications. However, the liver enzymes and total bilirubin of all donors were normalized within 1 month, and they recovered fully. Additionally, in a survey inquiring about cosmetic outcomes with a numeric scale of 1 through 10 (1, Not confident; 10, Very confident), the transverse incision had more satisfactory scores compared to the conventional big incision (9.80 vs. 6.17, P=0.001). In conclusion, the hybrid technique can be safely performed in donor right hepatectomy, with a minimal transverse skin incision, resulting in a good cosmetic outcome.

Park H.S.,Seoul National University
Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc | Year: 2014

Epidermal growth factor receptor (EGFR) is frequently overexpressed in triple-negative breast cancer and is emerging as a therapeutic target. EGFR gene copy number alteration and mutation are highly variable and scientists have been challenged to define their prognostic significance in triple-negative breast cancer. We examined EGFR protein expression, EGFR gene copy number alteration and mutation of exon 18 to 21 in 151 cases of triple-negative breast cancer and correlated these findings with clinical outcomes. In addition, intratumoral agreement of EGFR protein overexpression and gene copy number alteration was evaluated. EGFR overexpression was found in 97 of 151 cases (64%) and high EGFR gene copy number was detected in 50 cases (33%), including 3 gene amplification (2%) and 47 high polysomy (31%). Five EGFR mutations were detected in 4 of 151 cases (3%) and included G719A in exon 18 (n=1), V786M in exon 20 (n=1), and L858R in exon 21 (n=3). One case had two mutations (G719A and L858R). High EGFR copy number, but not EGFR mutation, correlated with EGFR protein overexpression. Intratumoral heterogeneity of EGFR protein overexpression and EGFR copy number alteration was not significant. In survival analyses, high EGFR copy number was found to be an independent prognostic factor for poor disease-free survival in patients with triple-negative breast cancer. Our findings showed that EGFR mutation was a rare event, but high EGFR copy number was relatively frequent and correlated with EGFR overexpression in triple-negative breast cancer. Moreover, high EGFR copy number was associated with poor clinical outcome in triple-negative breast cancer, suggesting that evaluation of EGFR copy number may be useful for predicting outcomes in patients with triple-negative breast cancer and for selecting patients for anti-EGFR-targeted therapy.

Ha K.-C.,Sejong University | Kye S.-H.,Seoul National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We examine various notions related to the optimality for entanglement witnesses arising from Choi-type positive linear maps. We found examples of optimal entanglement witnesses which are nondecomposable but are not "nondecomposable optimal entanglement witnesses" in the sense of Lewenstein, Kraus, Cirac, and Horodecki. We suggest using the terms PPTES witness and optimal PPTES witness in place of "nondecomposable entanglement witness" and "nondecomposable optimal entanglement witnesses" in order to avoid possible confusion. Here, PPTES refers entangled states with positive partial transposes. We also found examples of nonextremal optimal entanglement witnesses which are indecomposable. © 2012 American Physical Society.

Suyama T.,Seoul National University
Journal of High Energy Physics | Year: 2012

Some of supersymmetric Chern-Simons theories are known to exhibit supersymmetry breaking when the Chern-Simons level is less than a certain number. The mechanism of the supersymmetry breaking is, however, not clear from the field theory viewpoint. In this paper, we discuss vacuum states of N = 2 pure Chern-Simons theory and N = 2 Chern-Simons-matter theories of quiver type using related theories in which Chern-Simons terms are replaced with (anti-)fundamental chiral multiplets. In the latter theories, supersymmetry breaking can be shown to occur by examining that the vacuum energy is non-zero. © SISSA 2012.

Kim N.Y.,Seoul National University
Journal of Korean medical science | Year: 2013

The purpose of this study was to investigate the contribution of MSX1 gene to the risk of nonsyndromic cleft lip with or without cleft palate (NS-CL ± P) in the Korean population. The samples consisted of 142 NS-CL ± P families (9 with cleft lip, 26 with cleft lip and alveolus, and 107 with cleft lip and palate; 76 trios and 66 dyads). Three single nucleotide polymorphisms (SNPs: rs3821949, rs12532, and rs4464513) were tested for association with NS-CL ± P case-parent trios using transmission disequilibrium test (TDT) and conditional logistic regression models (CLRMs). Minor allele frequency, heterozygosity, χ(2) test for Hardy-Weinberg equilibrium, and pairwise linkage disequilibrium (LD) at each SNP were computed. The family- and haplotype-based association test programs were used to perform allelic and genotypic TDTs for individual SNPs and to fabricate sliding windows of haplotypes. Genotypic odds ratios (GORs) were obtained from CLRMs using R software. Although the family-based TDT indicated a meaningful association for rs3821949 (P = 0.028), the haplotype analysis did not reveal any significant association with rs3821949, rs12532, or rs4464513. The A allele at rs3821949 had a significant increased risk of NS-CL ± P (GOR, 1.64; 95% confidence interval,1.03-2.63; P = 0.038, additive model). A positive association is suggested between MSX1 rs3821949 and NS-CL ± P in the Korean population.

Choi S.H.,Seoul National University | Ginsberg H.N.,Columbia University
Trends in Endocrinology and Metabolism | Year: 2011

Insulin resistance (IR) affects not only the regulation of carbohydrate metabolism but all aspects of lipid and lipoprotein metabolism. IR is associated with increased secretion of VLDL and increased plasma triglycerides, as well as with hepatic steatosis, despite the increased VLDL secretion. Here we link IR with increased VLDL secretion and hepatic steatosis at both the physiologic and molecular levels. Increased VLDL secretion, together with the downstream effects on high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) size, is proatherogenic. Hepatic steatosis is a risk factor for steatohepatitis and cirrhosis. Understanding the complex inter-relationships between IR and these abnormalities of liver lipid homeostasis will provide insights relevant to new therapies for these increasing clinical problems. © 2011 Elsevier Ltd.

Cho Y.J.,Seoul National University
The International journal of oral & maxillofacial implants | Year: 2011

A biochemical approach to implant surface modification may offer an alternative to physicochemical and morphologic methods for obtaining desirable bone-implant interfaces. The objective of this study was to investigate the bone tissue response to anodized titanium implant surfaces coated with a poly(D,L-lactide-co-glycolide) (PLGA) solution mixed with 1α,25-diydroxyvitamin D3 (1α,25-(OH)2D3) via an electrospray technique. Threaded implants were manufactured and anodized under 300 V at 660 Hz for 3 minutes (control group). Half of the implants were then coated with 0.15 mL of the PLGA/1α,25-(OH)2D3 solution (5 μg/implant) via electrospray (experimental group). Surface topography was evaluated using field-emission scanning electron microscopy and optical interferometry. Forty-eight implants (12 implants per group per healing period) were surgically placed in random sites in the tibiae of 12 New Zealand white rabbits. After 4 and 12 weeks of healing, undecalcified ground sections were subjected to histologic and histomorphometric analyses. At week 4, the mean bone-to-implant contact ratio (BIC%) over the entire length of the implant in the experimental group was 37.08% ± 10.18%, versus 28.01% ± 8.70% in the control group. The mean BIC% value in the first four consecutive threads of the experimental group was 48.64% ± 15.92%, compared to 36.11% ±13.49% in the control group (P < .05). At week 12, the mean overall BIC% values were 39.10% ± 7.68% in the experimental group and 29.53% ± 9.49% in the control group. The mean BIC% value in the first four consecutive threads of the experimental group was 51.80% ± 16.41%, versus 37.35% ± 11.77% in the control group (P < .05). The current study demonstrated that the PLGA/1α,25-(OH)2D3 solution coating resulted in submicron-sized particles, which may stimulate bone formation adjacent to the surface of implants inserted into bone.

Muthiah M.,Chonnam National University | Park I.-K.,Chonnam National University | Cho C.-S.,Seoul National University
Biotechnology Advances | Year: 2013

Superparamagnetic iron oxide nanoparticles (SPIONs) are excellent MR contrast agents when coated with biocompatible polymers such as hydrophilic synthetic polymers, proteins, polysaccharides, and lipids, which improve their stability and biocompatibility and reduce their aggregation. Various biocompatible materials, coated or conjugated with targeting moieties such as galactose, mannose, folic acid, antibodies and RGD, have been applied to SPION surfaces to provide tissue specificity to hepatocytes, macrophages, and tumor regions in order to reduce non-specific uptake and improve biocompatibility. This review discusses the recent progress in the development of biocompatible and hydrophilic polymers for improving stability of SPIONs and describes the carbohydrates based biocompatible materials that are providing SPIONs with cell/tissue specificity as ligands. © 2013 Elsevier Inc.

Lee W.-J.,Seoul National University | Brey P.T.,Institute Pasteur du Laos
Annual Review of Cell and Developmental Biology | Year: 2013

Since Metchnikoff developed his views on the intestinal microflora, much effort has been devoted to understanding the role of gut microbiomes in metazoan physiology. Despite impressive data sets that have been generated by associating a phenotype-causing commensal community with its corresponding host phenotype, the field continues to suffer from descriptive and often contradictory reports. Hence, we cannot yet draw clear conclusions as to how the modifications of microbiomes cause physiological changes in metazoans. Unbiased, large-scale genetic screens to identify key genes, on both microbial and host sides, will be essential to gain mechanistic insights into gut-microbe interactions. The Drosophila genome-commensal microbiome genetic model has proven to be well suited to dissect the complex reciprocal cross talk between the host and its microbiota. In this review, we present a historical account, current views, and novel perspectives for future research directions based on the insights gleaned from the Drosophila gut-microbe interaction model. © 2013 by Annual Reviews. All rights reserved.

Fibroblast growth factors (FGFs) are known to play a critical role in bone growth and development, affecting both osteogenesis and chondrogenesis. Fibroblast growth factor 2 (FGF-2) is produced intracellularly by osteoblasts and secreted into the surrounding matrix in bone. The dose-dependent effects of FGF-2 were tested to examine the relationship between FGF-2 and osteoblast proliferation and differentiation. Tests used included a cell viability test, an alkaline phosphatase activity test, and a Western blot analysis. Cultures growing in the presence of FGF-2 showed an increased value for 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay and a decreased value for alkaline phosphatase activity. Results of the Western blot analysis showed that the addition of FGF-2 seems to decrease osteocalcin and bone morphogenetic protein receptor IA. These data show that FGF-2 in the tested dosage within MC3T3- E1 cells seems to affect proliferation and differentiation. Results of the Western blot analysis may add some possible mechanisms, and it may be suggested that treatment of FGF-2 may have an influence on the expression of bone morphogenetic protein receptors in osteoprecursor cells. Further elucidation of the mechanisms related to this mechanism within the in vivo model may be necessary to ascertain greater detail. Copyright © 2011 by Mutaz B. Habal, MD.

Kim S.,Massachusetts Institute of Technology | Kim S.,Seoul National University | Sauer R.T.,Massachusetts Institute of Technology
Genes and Development | Year: 2014

Intracellular proteases combat proteotoxic stress by degrading damaged proteins, but their activity must be carefully controlled to maintain cellular fitness. The activity of Escherichia coli DegP, a highly conserved periplasmic protease, is regulated by substrate-dependent allosteric transformations between inactive and active trimer conformations and by the formation of polyhedral cages that confine the active sites within a proteolytic chamber. Here, we investigate how these distinct control mechanisms contribute to bacterial fitness under heat stress. We found that mutations that increase or decrease the equilibrium population of active DegP trimers reduce high-temperature fitness, that a mutation that blocks cage formation causes a mild fitness decrease, and that combining mutations that stabilize active DegP and block cage formation generates a lethal rogue protease. This lethality is suppressed by an extragenic mutation that prevents covalent attachment of an abundant outermembrane lipoprotein to peptidoglycan and makes this protein an inhibitor of the rogue protease. Lethality is also suppressed by intragenic mutations that stabilize inactive DegP trimers. In combination, our results suggest that allosteric control of active and inactive conformations is the primary mechanism that regulates DegP proteolysis and fitness, with cage formation providing an additional layer of cellular protection against excessive protease activity. © 2014 Kim and Sauer.

To determine the initial compensation, preoperative decompensation, and postoperative compensation of the lower incisors according to the skeletal anteroposterior discrepancy and vertical type in skeletal Class III patients. The samples consisted of 68 skeletal Class III patients treated with two-jaw surgery and orthodontic treatment. Lateral cephalograms were taken before preoperative orthodontic treatment (T0) and before surgery (T1) and after debonding (T2). According to skeletal anteroposterior discrepancy/vertical type (ANB, criteria = -4°; SN-GoMe, criteria = 35°) at the T0 stage, the samples were allocated into group 1 (severe anteroposterior discrepancy/hypodivergent vertical type, N = 17), group 2 (moderate anteroposterior discrepancy/hypodivergent vertical type, N = 17), group 3 (severe anteroposterior discrepancy/hyperdivergent vertical type, N = 17), or group 4 (moderate anteroposterior discrepancy/hyperdivergent vertical type, N = 17). After measurement of variables, one-way analysis of variance with Duncan's multiple comparison test, crosstab analysis, and Pearson correlation analysis were performed. At T0, groups 3 and 2 exhibited the most and least compensated lower incisors. In group 2, good preoperative decompensation and considerable postoperative compensation resulted in different values for T0, T1, and T2 (IMPA, T0 < T2 < T1; P < .001). However, group 3 did not show significant changes in IMPA between stages. Therefore, groups 2 and 3 showed different decompensation achievement ratios (P < .05). Group 3 exhibited the worst ratios of decompensation and stability (24% and 6%, respectively, P < .001). Anteroposterior discrepancy/vertical type (ANB: P < .01 at T0 and T1, P < .001 at T2; SN-GoMe: P < .01, all stages) were strongly correlated with relative percentage ratio of IMPA to norm value. Skeletal anteroposterior discrepancy/vertical type results in differences in the amount and pattern of initial compensation, preoperative decompensation, and postoperative compensation of lower incisors in Class III patients.

Kim H.,Korea Institute of Energy Research | Moon S.H.,Seoul National University
Carbon | Year: 2011

Fuel-cell electrode catalysts with improved electrochemical properties have been prepared by dispersing Pt nanoparticles onto carbon nanotubes (CNT) using a chemical vapor deposition (CVD) method. (Trimethyl)methylcyclopentadienyl platinum (MeCpPtMe3) has been used as a Pt precursor in the CVD process and the CVD conditions have been optimized to disperse small Pt particles onto the CNT. Pt particles synthesized by CVD have a relatively uniform size of approximately 1 nm, which is substantially smaller than in the case of a commercial Pt/carbon black catalyst (≤4.5 nm) prepared by wet impregnation. The dispersion of Pt, estimated by CO chemisorption, is also more than 14% greater than the commercial catalyst with these smaller particles. The electrochemically active surface area (ESA), measured by cyclic voltammetry (CV), and the long-time durability of the surface area of Pt/CNT prepared by CVD are higher than those of the commercial catalyst. Consequently, the single cell performance of the former catalyst is superior to that of the latter one. © 2010 Elsevier Ltd. All rights reserved.

Yu S.,Harvard University | Kim H.Y.,Seoul National University | Chang Y.-J.,Academia Sinica, Taiwan | Dekruyff R.H.,Harvard University | Umetsu D.T.,Genentech
Journal of Allergy and Clinical Immunology | Year: 2014

Asthma is a complex and heterogeneous disease with several phenotypes, including an allergic asthma phenotype characterized by TH2 cytokine production and associated with allergen sensitization and adaptive immunity. Asthma also includes nonallergic asthma phenotypes, such as asthma associated with exposure to air pollution, infection, or obesity, that require innate rather than adaptive immunity. These innate pathways that lead to asthma involve macrophages, neutrophils, natural killer T cells, and innate lymphoid cells, newly described cell types that produce a variety of cytokines, including IL-5 and IL-13. We review the recent data regarding innate lymphoid cells and their role in asthma. © 2013 American Academy of Allergy, Asthma & Immunology.

Kim S.H.,Stanford University | Kim S.H.,Seoul National University | Kamaya A.,Stanford University | Willmann J.K.,Stanford University
Radiology | Year: 2014

With the introduction of molecularly targeted chemotherapeutics, there is an increasing need for defining new response criteria for therapeutic success because use of morphologic imaging alone may not fully assess tumor response. Computed tomographic (CT) perfusion imaging of the liver provides functional information about the microcirculation of normal parenchyma and focal liver lesions and is a promising technique for assessing the efficacy of various anticancer treatments. CT perfusion also shows promising results for diagnosing primary or metastatic tumors, for predicting early response to anticancer treatments, and for monitoring tumor recurrence after therapy. Many of the limitations of early CT perfusion studies performed in the liver, such as limited coverage, motion artifacts, and high radiation dose of CT, are being addressed by recent technical advances. These include a wide area detector with or without volumetric spiral or shuttle modes, motion correction algorithms, and new CT reconstruction technologies such as iterative algorithms. Although several issues related to perfusion imaging - such as paucity of large multicenter trials, limited accessibility of perfusion software, and lack of standardization in methods - remain unsolved, CT perfusion has now reached technical maturity, allowing for its use in assessing tumor vascularity in larger-scale prospective clinical trials. In this review, basic principles, current acquisition protocols, and pharmacokinetic models used for CT perfusion imaging of the liver are described. Various oncologic applications of CT perfusion of the liver are discussed and current challenges, as well as possible solutions, for CT perfusion are presented. © RSNA, 2014.

Lee H.-Y.,Seoul National University | Despres J.-P.,Laval University | Koh K.K.,Gachon University
Atherosclerosis | Year: 2013

Adipose tissue, which has been considered mainly as a site of energy storage and mobilization, is found in many depots throughout the body. Adipose depots may have structural properties such as, for instance, the fat pads located in the hands and feet and the periorbital fat supporting the eyes. Adipose tissue also shows remarkable regional heterogeneity. For instance, substantial differences have been reported in the metabolic properties of visceral (intra-abdominal) vs. subcutaneous adipose depots. Visceral adipose tissue (VAT) has active endocrine and paracrine functions with the secretion of various pro-inflammatory chemokines potentially contributing to the progression of atherosclerosis related with obesity. In addition, adipose depots surrounding the heart, such as epicardial (EAT) and perivascular adipose tissues (PAT) may also exert important roles in the pathogenesis of cardiovascular disease beyond the contribution of VAT due to their close anatomic relationships with vascular structures and myocardium. The purpose of the present review is to outline the current understanding of the pathophysiological links between EAT, PAT and atherosclerotic cardiovascular disease. Also, we discuss the current investigative methods for PAT quantification and discuss the potential impact of PAT on cardiovascular risk prediction. Finally, potential clinical implications of these notions are discussed. © 2013 Elsevier Ireland Ltd.

Nam E.H.,Seoul National University
Journal of microbiology and biotechnology | Year: 2013

The aim of this study was to investigate the characteristics of canine uropathogenic Escherichia coli (UPEC) and the interaction between canine UPEC and human bladder epithelial cells. Ten E. coli isolates collected from dogs with cystitis were analyzed for antimicrobial resistance patterns, the presence of virulence factors, and biofilm formation. The ability of these isolates to induce cytotoxicity, invade human bladder epithelial cells, and stimulate an immune response was also determined. We observed a high rate of antimicrobial resistance among canine UPEC isolates. All virulence genes tested (including adhesins, iron acquisition, and protectin), except toxin genes, were detected among the canine UPEC isolates. We found that all isolates showed varying degrees of biofilm formation (mean, 0.26; range, 0.07 to 0.82), using a microtiter plate assay to evaluate biofilm formation by the isolates. Cytotoxicity to human bladder epithelial cells by the canine UPEC isolates increased in a time-dependent manner, with a 56.9% and 36.1% reduction in cell viability compared with the control at 6 and 9 h of incubation, respectively. We found that most canine UPEC isolates were able to invade human bladder epithelial cells. The interaction between these isolates and human bladder epithelial cells strongly induced the production of proinflammatory cytokines such as IL-6 and IL-8. We demonstrated that canine UPEC isolates can interact with human bladder epithelial cells, although the detailed mechanisms remain unknown. The results suggest that canine UPEC isolates, rather than dogspecific pathogens, have zoonotic potential.

Treatment remains uncertain for IgA nephropathy patients with mild to moderate proteinuria, for whom anti-hypertensive medication or the RAS blocker is not applicable due to low blood pressure. A double blinded randomized trial. The anti-proteinuric effect of tacrolimus was explored for 40 biopsy-proven mild IgA nephropathies for 16 weeks. We randomly assigned patients either to receive tacrolimus or placebo with stratification by using a renin angiotensin system blocker. The primary outcome was the percentage change of final UACR compared to the baseline value (pcUACR). The mean value of pcUACR at 12-week and 16-week visits (primary outcome) was decreased more in the Tac group compared to the control group (-52.0±26.4 vs -17.3±29.3%, p = 0.001). At each visit, pcUACR was also decreased more in the Tac group compared to the control group. In the Tac group, the pcUACRs were -60.2±28.2%, -62.2±33.9%, -48.5±29.8%, and -55.5±24.0%, and, in the control group, -6.8±32.2%, -2.5±35.9%, -12.7±34.2%, and -21.9±30.6%, at 4-week, 8-week, 12-week, and 16-week visits, respectively. The pre-defined secondary outcomes were better in the Tac group compared to the control group. The frequency of decrease in pcUACR and percentage change of UPCR (pcUPCR) ≥50% at 16 weeks were 65.0% (13/20) and 55.0% (11/20)in the Tac group, and 25.0% (5/20) and 15.0% (3/20), in the control group, respectively (p = 0.025 for pcUACR and p = 0.019 for pcUPCR). However, tacrolimus wasn't effective with a dose of 0.05 mg/kg/day in patients taking ARB. The adverse events were tolerable. Tacrolimus effectively reduced proteinuria in IgA nephropathy with normal blood pressure. This suggested that tacrolimus could be an alternative to corticosteroid and RAS blocker for IgA nephropathy patients who cannot endure anti-hypertensive medication. Clinicaltrial.gov NCT1224028.

Chae J.,Seoul National University
Astrophysical Journal | Year: 2010

The existence and behavior of vertical fine structures of plasma - threads and knots - are a significant observational clue to understanding the magnetic structure and dynamics of quiescent prominences on the quiet Sun. Based on the equation of motion in ideal MHD, we reason that the non-hydrostatic support of plasma against gravity in general requires either the motion of plasma with a high value of downward acceleration (dynamical support) or the role of horizontal magnetic fields (magnetic support). By carefully tracking the motion of several bright threads seen in a hedgerow prominence observed by the Solar Optical Telescope aboard Hinode, we confirm that these threads are essentially static and stable, which negates the dynamic support. The application of the Kippenhahn-Schlüter solution suggests that they may be supported by sagged magnetic field lines with a sag angle of about 43°. We also track several bright descending knots and find that their descending speeds range from 10 to 30 km s-1, with a mean value of 16 km s-1, and their vertical accelerations from -0.10 to 0.10 km s-2, with a mean of practically zero. This finding suggests that these knots are basically supported by horizontal magnetic fields against gravity even when they descend, and the complex variations of their descending speeds should be attributed to small imbalances between gravity and the force of magnetic tension. Furthermore, some knots are observed to impulsively get accelerated downward from time to time. We conjecture that these impulsive accelerations are a result of magnetic reconnection and the subsequent interchange of magnetic configuration between a knot and its surrounding structure. It is proposed that this process of reconnection and interchange not only initiates the descending motion of the knots, but also allows knots to keep falling long distance through the medium permeated by horizontal magnetic fields. © 2010. The American Astronomical Society. All rights reserved.

We report the case of a 37-year-old man with a high myopic keratoconus eye that was treated with a posterior chamber toric implantable collamer lens (ICL) in Korea. The patient had a history of contact lens intolerance and did not want to have a corneal transplantation. His uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity were 0.02 and 0.4 in the left eye, respectively. Preoperatively, the manifest refraction was -12.0 -3.5 × 30A. Postoperatively, the manifest refraction was -1.75 × 180A. UCVA improved markedly after implantation. No intraoperative or postoperative complications were observed during 20 months of follow-up. Toric ICL implantation may be a possible alternative surgical option for the visual rehabilitation of high myopic astigmatism in keratoconus patients with rigid gas permeable contact lens intolerance and in patients who do not want to get a corneal transplant.

We previously reported that Treponema denticola, a periodontal pathogen, suppressed the expression of human beta-defensins (HBDs) and IL-8 in human gingival epithelial cells. To clarify the receptor(s) involved in the suppression of HBD-2, immortalized gingival epithelial (HOK-16B) cells were infected with live or heat-killed T. denticola for 24 h, and the expression of HBD-2 was examined by real-time RT-PCR. Live T. denticola, but not heat-killed bacteria, suppressed the expression of HBD-2 about 40%. Time courses of suppression revealed that T. denticola suppressed HBD-2 expression only at late time points, which was accompanied with the suppression of TNFalpha production. Neutralization of TNFalpha with an antibody abrogated the suppressive effect of T. denticola on HBD-2. Accordingly, heat-killed T. denticola did not suppress TNFalpha production. Knock-down of toll-like receptor (TLR) 2 via RNA interference reversed the suppressive effect of T. denticola on the expression of HBD-3, but not on the production of TNFalpha. Collectively, T. denticola suppresses the expression of HBD-2 in gingival epithelial cells by inhibiting the TLR2 axis and TNFalpha production, which may contribute to the pathogenesis of periodontitis by T. denticola.

Ahn H.-R.,Seoul National University
IEEE Transactions on Microwave Theory and Techniques | Year: 2012

Design methods are, for the first time, suggested for the complex impedance transformers, to solve the conventional problem of imaginary value of characteristic impedance of transmission-line sections. The complex impedance transformers consist of only transmission-line sections, and the design formulas are the function of the reflection coefficients of the complex termination impedances. Firstly, the impedance transformers that transform a complex impedance into a real one are discussed. Secondly, those transforming a complex impedance to another complex one are studied. For the impedance transformers of the first type, the regions of the Smith chart where one complex impedance can be transformed into one real one by only one transmission-line section are called allowed regions, while the outside forbidden regions. Depending on where the complex impedances are located, a method to reduce the size is discussed in more detail. For the second case where both termination impedances are complex, the complex conjugate of one of two complex impedances should be located on a Smith chart for maximum power transfer. The design formulas are then obtained in a similar manner. To validate the design formulas, three impedance transformers terminated in a fixed complex impedance of (100 - j30)Ω and three real impedances of 50, 60, and 80 Ω are fabricated and measured. The measured results show quite good agreement with prediction, return losses of 30-38 dB being achieved around the design center frequency of 2 GHz. © 1963-2012 IEEE.

Jin J.,Seoul National University
Virchows Archiv : an international journal of pathology | Year: 2011

Liver fibrosis and its end-stage disease, cirrhosis, are major worldwide healthcare burdens. In this study, we evaluated the inhibitory effects of nicotinamide (NA) on rat hepatic fibrogenesis and investigated its underlying mechanism. We examined the inhibitory effects of NA in vivo by using F344 rats in a thioacetamide (TAA)-induced fibrogenesis model and assessed the inhibitory effects in vitro by using the rat hepatic stellate cell line THSC-Cl6. In vivo, NA significantly attenuated liver fibrosis in TAA-treated rats as assessed by histological analysis using hematoxylin-eosin and Masson's trichrome staining. In vitro, NA inhibited viability of THSC-Cl6 cells in a dose- and time-dependent manner, suppressed DNA synthesis, and induced apoptosis. Transcription of collagen mRNA and expression of alpha smooth muscle actin (the hallmark of activated hepatic stellate cells) were reduced by NA. Expression of the cell cycle-related proteins cyclin E, cyclin D1, and cyclin-dependent kinase (cdk)4, was reduced by NA treatment, but expression of cyclin A and cdk2 was not. Expression of the cdk inhibitors p16 and p21 was decreased by NA treatment, whereas expression of p27 was increased. It appears that NA inhibits rat hepatic fibrogenesis by suppressing DNA synthesis and enhancing apoptosis of hepatic stellate cells.

Early reperfusion after myocardial ischemia that is essential for tissue salvage also causes myocardial and vascular injury. Cardioprotection during reperfusion therapy is an essential aspect of treating myocardial infarction. Angiopoietin-1 is an endothelial-specific angiogenic factor. The potential effects of angiopoietin-1 on cardiomyocytes and vascular cells undergoing reperfusion have not been investigated. We propose a protective mechanism whereby angiopoietin-1 increases the integrity of the endothelial lining and exerts a direct survival effect on cardiomyocytes under myocardial ischemia followed by reperfusion. First, we found that angiopoietin-1 prevents vascular leakage through regulating vascular endothelial (VE)-cadherin phosphorylation. The membrane expression of VE-cadherin was markedly decreased on hypoxia/reoxygenation but was restored by angiopoietin-1 treatment. Interestingly, these effects were mediated by the facilitated binding between SH2 domain-containing tyrosine phosphatase (SHP2) or receptor protein tyrosine phosphatase μ (PTPμ) and VE-cadherin, leading to dephosphorylation of VE-cadherin. siRNA against SHP2 or PTPμ abolished the effect of angiopoietin-1 on VE-cadherin dephosphorylation and thereby decreased levels of membrane-localized VE-cadherin. Second, we found that angiopoietin-1 prevented cardiomyocyte death, although cardiomyocytes lack the angiopoietin-1 receptor Tie2. Angiopoietin-1 increased cardiomyocyte survival through integrin-β1-mediated extracellular signal-regulated kinase (ERK) phosphorylation, which inhibited caspase-9 through phosphorylation at Thr125 and subsequently reduced active caspase-3. Neutralizing antibody against integrin-β1 blocked these protective effects. In a mouse myocardial ischemia/reperfusion model, angiopoietin-1 enhanced cardiac function and reduction in left ventricular-end systolic dimension (LV-ESD) and left ventricular-end diastolic dimension (LV-EDD) with an increase in ejection fraction (EF) and fractional shortening (FS). Our findings suggest the novel cardioprotective mechanisms of angiopoietin-1 that are achieved by reducing both vascular leakage and cardiomyocyte death after ischemia/reperfusion injury.

Okada T.,RIKEN | Sakatani Y.,Seoul National University
Journal of High Energy Physics | Year: 2015

Abstract: There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective. © 2015, The Author(s).

Kang K.W.,Seoul National University
Angewandte Chemie - International Edition | Year: 2015

Altered metabolism is a critical part of cancer cell properties, but real-time monitoring of metabolomic profiles has been hampered by the lack of a facile method. Here, we propose real-time metabolomic monitoring of live cancer cells using 13C6-glucose and heteronuclear two-dimensional (2D) NMR. The method allowed for metabolomic differentiation between cancer and normal cells on the basis of time-dependent changes in metabolite concentrations. Cancer cells were found to have large in- and out-flux of pyruvate as well as increased net production of alanine and acetate. The method also enabled evaluation of the metabolic effects of galloflavin whose anticancer effects have been attributed to its specific inhibition of lactate dehydrogenase. Our approach revealed previously unknown functional targets of galloflavin, which were further confirmed at the protein levels. Our method is readily applicable to the study of metabolic alterations in other cellular disease model systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim T.,Korea Basic Science Institute | Hyeon T.,Seoul National University
Nanotechnology | Year: 2014

During the last decade, various functional nanostructured materials with interesting optical, magnetic, mechanical and chemical properties have been extensively applied to biomedical areas including imaging, diagnosis and therapy. In therapeutics, most research has focused on the application of nanoparticles as potential delivery vehicles for drugs and genes, because nanoparticles in the size range of 2-100 nm can interact with biological systems at the molecular level, and allow targeted delivery and passage through biological barriers. Recent investigations have even revealed that several kinds of nanomaterials are intrinsically therapeutic. Not only can they passively interact with cells, but they can also actively mediate molecular processes to regulate cell functions. This can be seen in the treatment of cancer via anti-angiogenic mechanisms as well as the treatment of neurodegenerative diseases by effectively controlling oxidative stress. This review will present recent applications of inorganic nanoparticles as therapeutic agents in the treatment of disease. © 2014 IOP Publishing Ltd.

Lifestyle factors have been chronologically changed into western style ones, which could result in the rapid increase of breast cancer incidence in Korea. It is plausible that reproductive factors through hormonal mechanisms are differentially related to the risk of breast cancer subtypes. We investigated the association of reproductive risk factors on breast cancer by birth year groups and also evaluated the differential associations on the hormone receptor-defined subtypes. Using the data from the Seoul Breast Cancer Study (SeBCS), a multicenter case-control study, 3,332 breast cancer patients and 3,620 control subjects were analyzed. The distribution of subtypes among cases was as follows: 61.0 % estrogen receptor (ER)-positive, 51.9 % progesterone receptor (PR)-positive, and 43.4 % both ER/PR-positive status, respectively. Polytomous logistic regression and Wald tests for heterogeneity have been used across the subtypes. The frequencies of reproductive-related risk factors including early age at menarche, nulligravid, age at first full-term pregnancy (FFTP), duration of estrogen exposure before FFTP (EEBF), less number of children, never breastfeeding, and short duration of breastfeeding has increased as women were born later in both cases and controls, respectively (p trend < 0.0001. Among breast cancer patients, either ER- or PR-positive subtypes were increased in women born in 1960s compared to women born in 1940s. Early age at menarche increased the risk of breast cancer regardless of the subtypes while nulligravid, late age at FFTP, and longer duration of EEBP were associated with hormone receptor-positive cancer risk only (p heterogeneity < 0.05), which associations were stronger among women born later. Our results suggest that the associations of age at menarche, parity, age at FFTP, and duration of EEBF with breast cancer risk were different based on the hormone receptor status and birth year groups in Korea.

A 37-year-old male presented with fever and jaundice was diagnosed as hepatitis A complicated with progressive cholestasis and severe autoimmune hemolytic anemia. He was treated with high-dose prednisolone (1.5 mg/kg), and eventually recovered. His initial serum contained genotype IA hepatitis A virus (HAV), which was subsequently replaced by genotype IIIA HAV. Moreover, at the time of development of hemolytic anemia, he became positive for immunoglobulin M (IgM) anti-hepatitis E virus (HEV). We detected HAV antigens in the liver biopsy specimen, while we detected neither HEV antigen in the liver nor HEV RNA in his serum. This is the first report of hepatitis A coinfected with two different genotypes manifesting with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive IgM anti-HEV.

Chai J.-Y.,Seoul National University
Infection and Chemotherapy | Year: 2013

Status and emerging issues in the use of praziquantel for treatment of human trematode and cestode infections are briefly reviewed. Since praziquantel was first introduced as a broadspectrum anthelmintic in 1975, innumerable articles describing its successful use in the treatment of the majority of human-infecting trematodes and cestodes have been published. The target trematode and cestode diseases include schistosomiasis, clonorchiasis and opisthorchiasis, paragonimiasis, heterophyidiasis, echinostomiasis, fasciolopsiasis, neodiplostomiasis, gymnophalloidiasis, taeniases, diphyllobothriasis, hymenolepiasis, and cysticercosis. However, Fasciola hepatica and Fasciola gigantica infections are refractory to praziquantel, for which triclabendazole, an alternative drug, is necessary. In addition, larval cestode infections, particularly hydatid disease and sparganosis, are not successfully treated by praziquantel. The precise mechanism of action of praziquantel is still poorly understood. There are also emerging problems with praziquantel treatment, which include the appearance of drug resistance in the treatment of Schistosoma mansoni and possibly Schistosoma japonicum, along with allergic or hypersensitivity reactions against praziquantel treatment. To cope with and overcome these problems, combined use of drugs, i.e., praziquantel and other newly introduced compounds such as triclabendazole, artemisinins, and tribendimidine, is being tried. © 2013 by The Korean Society of Infectious Diseases.

Roh Y.R.,Seoul National University
Korean journal of ophthalmology : KJO | Year: 2011

To evaluate the predictability of intraocular lens (IOL) power calculations using the IOLMaster and four different IOL power calculation formulas (Haigis, Hoffer Q, SRK II, and SRK/T) for cataract surgery in eyes with a short axial length (AL). The present study was a retrospective comparative analysis which included 25 eyes with an AL shorter than 22.0 mm that underwent uneventful phacoemulsification with IOL implantation from July 2007 to December 2008 at Seoul National University Boramae Hospital. Preoperative AL and keratometric power were measured by the IOLMaster, and power of the implanted IOL was determined using Haigis, Hoffer Q, SRK II, and SRK/T formulas. Postoperative refractive errors two months after surgery were measured using automatic refracto-keratometry (Nidek) and were compared with the predicted postoperative power. The mean absolute error (MAE) was defined as the average of the absolute value of the difference between actual and predicted spherical equivalences of postoperative refractive error. The MAE was smallest with the Haigis formula (0.37 ± 0.26 diopter [D]), followed by those of SRK/T (0.53 ± 0.25 D), SRK II (0.56 ± 0.20 D), and Hoffer Q (0.62 ± 0.16 D) in 25 eyes with an AL shorter than 22.0 mm. The proportion with an absolute error (AE) of less than 1 D was greatest in the Haigis formula (96%), followed by those in the SRK II (88%), SRK-T (84%), and Hoffer Q (80%). The MAE was less than 0.7 D and the proportion of AE less than 1 D was more than 80% in all formulas. The IOL power calculation using the Haigis formula showed the best results for postoperative power prediction in short eyes.

Kim M.,Seoul National University
Korean journal of ophthalmology : KJO | Year: 2011

To evaluate the changes in anterior chamber depth (ACD) and angle width induced by phacoemulsification and intraocular lens (IOL) implantation in normal eyes using anterior segment optical coherence tomography (AS-OCT). Forty-five eyes (45 patients) underwent AS-OCT imaging to evaluate anterior chamber configuration before and 2 days after phacoemulsification and IOL implantation. We analyzed the central ACD and angle width using different methods: anterior chamber angle (ACA), trabecular-iris angle (TIA), angle opening distance (AOD), and trabecular iris surface area (TISA) in the nasal and temporal quadrants. Comparison between preoperative and postoperative measurement was done using paired t-tests and each of the angle parameters was analyzed with Pearson correlation testing. Subgroup analyses according to the IOL and axial length were performed with a general multivariate linear model adjusted for age. Before surgery, the mean anterior chamber angle widths were 23.21 ± 6.70° in the nasal quadrant and 24.89 ± 7.66° in the temporal quadrant. The mean central ACD was 2.75 ± 0.43 mm. After phacoemulsification and IOL implantation, the anterior chamber angle width increased significantly to 35.16 ± 4.65° in the nasal quadrant (p = 0.001) and 36.03 ± 4.86° in the temporal quadrant (p = 0.001). Also, central ACD increased to 4.14 ± 0.31 mm (p = 0.001). AOD, TISA, and TIA increased significantly after cataract surgery and showed positive correlation with ACA. After cataract surgery, the ACD and angle width significantly increased in eyes with cataract. AS-OCT is a good method for obtaining quantitative data regarding anterior chamber configuration. © 2011 The Korean Ophthalmological Society

Ebell M.H.,University of Georgia | Jang W.,Seoul National University | Shen Y.,University of Georgia | Geocadin R.G.,Johns Hopkins University
JAMA Internal Medicine | Year: 2013

IMPORTANCE: Informing patients and providers of the likelihood of survival after in-hospital cardiac arrest (IHCA), neurologically intact or with minimal deficits, may be useful when discussing do-not-attempt-resuscitation orders. OBJECTIVE: To develop a simple prearrest point score that can identify patients unlikely to survive IHCA, neurologically intact or with minimal deficits. DESIGN, SETTING, AND PARTICIPANTS: The study included 51 240 inpatients experiencing an index episode of IHCA between January 1, 2007, and December 31, 2009, in 366 hospitals participating in the Get With the Guidelines- Resuscitation registry. Dividing data into training (44.4%), test (22.2%), and validation (33.4%) data sets, we used multivariate methods to select the best independent predictors of good neurologic outcome, created a series of candidate decision models, and used the test data set to select the model that best classified patients as having a very low (<1%), low (1%-3%), average (>3%-15%), or higher than average (>15%) likelihood of survival after in-hospital cardiopulmonary resuscitation for IHCA with good neurologic status. The final model was evaluated using the validation data set. MAIN OUTCOMES AND MEASURES: Survival to discharge after in-hospital cardiopulmonary resuscitation for IHCA with good neurologic status (neurologically intact or with minimal deficits) based on a Cerebral Performance Category score of 1. RESULTS: The best performing model was a simple point score based on 13 prearrest variables. The C statistic was 0.78 when applied to the validation set. It identified the likelihood of a good outcome as very low in 9.4%of patients (good outcome in 0.9%), low in 18.9%(good outcome in 1.7%), average in 54.0% (good outcome in 9.4%), and above average in 17.7%(good outcome in 27.5%). Overall, the score can identify more than one-quarter of patients as having a low or very low likelihood of survival to discharge, neurologically intact or with minimal deficits after IHCA (good outcome in 1.4%). CONCLUSIONS AND RELEVANCE: The Good Outcome Following Attempted Resuscitation (GO-FAR) scoring system identifies patients who are unlikely to benefit from a resuscitation attempt should they experience IHCA. This information can be used as part of a shared decision regarding do-not-attempt-resuscitation orders. Copyright 2013 American Medical Association. All rights reserved.

Gustavsson A.,Sogang University | Gustavsson A.,Seoul National University
Journal of High Energy Physics | Year: 2011

We extend the hermitian three-algebra formulation of ABJM theory to include U(1) factors. With attention payed to extra U(1) factors, we refine the classification of N = 6 ABJM theories. We argue that essentially the only allowed gauge groups are SU(N)×SU(N), U(N)×U(M) and Sp(N)×U(1) and that we have only one independent Chern-Simons level in all these cases. Our argument is based on integrality of the U(1) Chern-Simons levels and supersymmetry. A relation between monopole operators and Wilson lines in Chern-Simons theory suggests certain gauge representations of the monopole operators. From this we classify cases where we can not expect enhanced N = 8 supersymmetry. We also show that there are two equivalent formulations of N = 5 ABJM theories, based on hermitian three-algebra and quaternionic three-algebra respectively. We suggest properties of monopoles in N = 5 theories and show how these monopoles may enhance supersymmetry from N = 5 to N = 6. © SISSA 2011.

Rey S.-J.,Seoul National University | Suyama T.,Institute for Advanced Study
Journal of High Energy Physics | Year: 2011

Using localization, matrix model and saddle-point techniques, we determine exact behavior of circular Wilson loop in N = 2 superconformal (quiver) gauge theories in the large number limit of colors. Focusing at planar and large 't Hooft couling limits, we compare its asymptotic behavior with well-known exponential growth of Wilson loop in N = 4 super Yang-Mills theory with respect to 't Hooft coupling. For theory with gauge group SU(N) coupled to 2N fundamental hypermultiplets, we find that Wilson loop exhibits non-exponential growth - at most, it can grow as a power of 't Hooft coupling. For theory with gauge group SU(N)×SU(N) and bifundamental hypermultiplets, there are two Wilson loops associated with two gauge groups. We find Wilson loop in untwisted sector grows exponentially large as in N = 4 super Yang-Mills theory. We then find Wilson loop in twisted sector exhibits non-analytic behavior with respect to difference of the two 't Hooft coupling constants. By letting one gauge coupling constant hierarchically larger/smaller than the other, we show that Wilson loops in the second type theory interpolate to Wilson loops in the first type theory. We infer implications of these findings from holographic dual description in terms of minimal surface of dual string worldsheet. We suggest intuitive interpretation that in both classes of theory holographic dual background must involve string scale geometry even at planar and large 't Hooft coupling limit and that new results found in the gauge theory side are attributable to worldsheet instantons and infinite resummation therein. Our interpretation also indicates that holographic dual of these gauge theories is provided by certain non-critical string theories. © SISSA 2011.

Chae C.,Seoul National University
Virus Research | Year: 2012

This review describes the characterization of porcine circovirus type 2 (PCV2), the field situation of porcine circovirus-associated disease (PCVAD) and the PCV2 vaccine in Korea. PCVAD has been considered the most devastating disease in Korean livestock history since its first outbreak in 1999. Postweaning multisystemic wasting syndrome (PMWS) and porcine respiratory disease complex (PRDC) are the most common clinical forms of PCVAD. Interestingly, only PCV2b strains have been isolated from pigs with PMWS since 2005, but only PCV2a strains were isolated from pigs with PMWS in 2000 to 2001. Clinically, PMWS is divided into two stages: early and late. Early PMWS primarily occurs in pigs between 4 and 8 weeks of age. This form is a typical presentation of PMWS and is characterized clinically by wasting, decreased weight gain, enlarged lymph nodes, and dyspnea. Late PMWS primarily occurs in pigs between 8 and 12 weeks of age. The main clinical manifestation is diarrhea, which is often accompanied by salmonellosis coinfection. In recent years, the PCVAD disease pattern has slightly changed. The occurrence of PMWS has decreased while PRDC cases are increasing in frequency. © 2011 Elsevier B.V.

Verma L.,Peraso Technologies | Fakharzadeh M.,Peraso Technologies | Choi S.,Seoul National University
IEEE Wireless Communications | Year: 2013

The advent of bandwidth-hungry wireless applications such as large file transfer, high definition video streaming, wireless display, and cellular data offload highlight the impending need for larger bandwidth and super speed WiFi links exceeding 1 Gb/s. This article introduces two emerging standards likely to shake the wireless world, namely IEEE 802.11ac and IEEE 802.11ad, and identifies the challenges in the path of multi-gigabit WiFi. We study the suitability of these standards for the new usage models enlisted in this article. © 2002-2012 IEEE.

Ahn D.W.,Seoul National University
The Korean journal of hepatology | Year: 2011

Needle-track seeding is a rare but important complication of diagnostic and therapeutic ultrasound (US)-guided procedures in hepatocellular carcinoma (HCC). We examined the frequency of needle-track seeding after US-guided percutaneous ethanol injection (PEI), fine-needle aspiration biopsy (FNAB), and percutaneous transhepatic biliary drainage (PTBD) in order to determine the appropriate treatment for needle-track seeding and its clinical outcome. We analyzed the clinical characteristics and treatment outcomes in eight patients who experienced needle-track seeding from HCC after an US-guided procedure (FNAB, PEI, or PTBD) between January 1990 and July 2004. Seven (0.14%) of 5,092 patients who experienced needle-track seeding (2 after PEI, 4 after FNAB, and 1 after PTBD) during the study period and 1 other patient who experienced needle-track seeding recently were recruited for this study. Two of the eight patients underwent mass excision and the other six patients underwent en-bloc wide excision for the needle-track seeding. Tumors recurred in the needle-tracks in both patients who underwent mass excision but not in the six patients who underwent en-bloc wide excision. Mortality occurred in three patients who experienced the recurrence and progression of intrahepatic HCC. The incidence of needle-track seeding after US-guided procedures in HCC was 0.14%. En-bloc wide excision seems to be the optimal treatment for minimizing the probability of tumor recurrence due to needle-track seeding.

Kim J.-H.,University of California at Santa Cruz | Lee J.,Seoul National University
Monthly Notices of the Royal Astronomical Society | Year: 2013

Late-type low surface brightness galaxies (LSBs) are faint disc galaxies with centralmaximum stellar surface densities below100 Mȯ pc-2. The currently favoured scenario for their origin is that LSBs have formed in fast-rotating haloes with large angular momenta.We present the first numerical evidence for this scenario using a suite of self-consistent hydrodynamic simulations of a 2.3 × 1011Mȯ galactic halo, in which we investigate the correlations between the disc stellar/gas surface densities and the spin parameter of its host halo. A clear anticorrelation between the surface densities and the halo spin parameter λ is found. That is, as the halo spin parameter increases, the disc cutoff radius at which the stellar surface density drops below 0.1 Mȯ pc-2 monotonically increases, while the average stellar surface density of the disc within that radius decreases. The ratio of the average stellar surface density for the case of λ = 0.03 to that for the case of λ = 0.14 reaches more than 15. We demonstrate that the result is robust against variations in the baryon fraction, confirming that the angular momentum of the host halo is an important driver for the formation of LSBs. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Lee S.,Seoul National University
Cell cycle (Georgetown, Tex.) | Year: 2010

CEP 215 is a human orthologue of Drosophila centrosomin which is a core centrosome component for the pericentriolar matrix protein recruitment. Recent investigations revealed that CEP 215 is required for centrosome cohesion, centrosomal attachment of the gamma-TuRC, and microtubule dynamics. However, it remains obscure how CEP 215 functions for recruitment of the centrosomal proteins during the centrosome cycle. Here, we investigated a role of CEP 215 during mitosis. Knockdown of CEP 215 resulted in characteristic mitotic phenotypes, including monopolar spindle formation, a decrease in distance between the spindle pole pair, and detachment of the centrosomes from the spindle poles. We noticed that CEP 215 is critical for centrosomal localization of dynein throughout the cell cycle. As a consequence, the selective centrosomal proteins were not recruited to the centrosome properly. Finally, the centrosomal localization of CEP 215 also depends on the dynein-dynactin complex. Based on the results, we propose that CEP 215 regulates a dynein-dependent transport of the pericentriolar matrix proteins during the centrosome maturation.

Kim J.,Seoul National University
Telemedicine and e-Health | Year: 2014

Background: With the ever-increasing availability of health information technology (HIT) enabling health consumers to measure, store, and manage their health data (e.g., self-tracking devices), more people are logging and managing their own health data for the purpose of promoting general well-being. To develop and implement effective and efficient strategies for improving personal monitoring devices, a rigorous theoretical framework to explain the health consumer's attitude, intention, and behavior needs to be established. The aim of this study is to verify the HIT acceptance model (HITAM) in the context of the health consumer's attitude, behavioral intention, and behavior of utilizing self-trackers. Furthermore, the study aims to gain better understanding of self-tracking behavior in the context of logging daily activity level, sleep patterns, and dietary habits. Subjects and Methods: Forty-four female college students were selected as voluntary study participants. They used self-trackers for activity, sleep, and diet monitoring for 90 or more consecutive days. The logged data were analyzed and fitted to the HITAM to verify whether the model was suitable for capturing the various behavioral and intention-related characteristics observed. Results: The overall fitness indices for the HITAM using the field data yielded an acceptable fitness to the model, with all path coefficients being statistically significant. The model accounts for 66.8% of the variance in perceived usefulness, 43.9% of the variance in perceived ease of use, 83.1% of the variance in attitude, and 48.4% of the variance in behavioral intention. The compliance ranking of self-tracking behavior, in order of decreasing compliance, was activity, sleep, and diet. This ranking was consistent with that of ease of use of the personal monitoring device used in the study. Conclusions: The HITAM was verified for its ability to describe the health consumer's attitude, behavioral intention, and behavior. The analysis indicated that the ease of use of a particular HIT device stands as the most significant barrier in the way of increasing the efficacy of self-tracking. © Copyright 2014, Mary Ann Liebert, Inc. 2014.

Lee H.,Seoul National University
Solid State Communications | Year: 2010

We study the adsorption of the molecular hydrogen on boron-doped polypyrrole ((C4BH3)n) using first-principles density functional calculations. We find that the binding energy of H 2 molecules is slightly reduced to 0.39 eVH2 from 0.51 eVH2 as the number of adsorbed H2 molecules increases. This is in sharp contrast to the case of boron-doped fullerenes where the binding energy is drastically reduced as the number of adsorbed H2 molecules increases. We find that the enhancement of H2 adsorption is due to a local charge transfer by H2 adsorption in the B-doped polypyrrole as opposed to a delocalized charge transfer in the B-doped fullerenes. Our finding shows that B-doped carbon systems could be utilized for room temperature hydrogen storage. © 2010 Elsevier Ltd. All rights reserved.

Min Y.-G.,Seoul National University
Allergy, Asthma and Immunology Research | Year: 2010

Treatment of AR requires a stepwise approach depending on the severity and duration of symptoms. Treatment options for AR consist of allergen avoidance, pharmacotherapy, immunotherapy and surgery. For the mechanisms of AR, anti-IgE antibody and specific antibody to cytokines such as IL-4 or IL-5 that correlate with allergic inflammation have recently emerged. SLIT is currently widely used due to its efficacy, safety and convenience, which replaces subcutaneous immunotherapy. Although allergen avoidance and immunotherapy are theoretically ideal, antihistamines and intranasal corticosteroids will play the main role in the management of AR until an innovative treatment develops. However, patients' main symptom, the duration and severity of AR, patients' compliance, safety of medication and cost-effectiveness should be considered when treatment options are chosen. In conclusion, physicians should be aware of etiology, pathophysiology, symptoms, signs and diseases related to AR in order to make a correct diagnosis and choose a proper treatment option for each patient. © Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology • The Korean Academy of Pediatric Allergy and Respiratory Disease.

Cheon J.H.,Seoul National University
Journal of Cryptology | Year: 2010

Let g be an element of prime order p in an abelian group, and let α ∈ ℤ p. We show that if g,g α, and g αd are given for a positive divisor d of p - 1, the secret key α can be computed deterministically in O(√p/d + √d) exponentiations by using O(max{√p/d,√d}) storage. If g αi (i = 0, 1, 2, . . . , 2d) is given for a positive divisor d of p + 1, α can be computed in O(√p/d + d) exponentiations by using O(max{√p/d,√d}) storage. We also propose space-efficient but probabilistic algorithms for the same problem, which have the same computational complexities with the deterministic algorithm. As applications of the proposed algorithms, we show that the strong Diffie-Hellman problem and related problems with public g α, . . . , g αd have computational complexity up to O(√d/log p) less than the generic algorithm complexity of the discrete logarithm problem when p - 1 (resp. p + 1) has a divisor d ≤ p 1/2 (resp. d ≤ p 1/3). Under the same conditions for d, the algorithm is also applicable to recovering the secret key in O(√p/d · log p) for Boldyreva's blind signature scheme and the textbook ElGamal scheme when d signature or decryption queries are allowed. © International Association for Cryptologic Research 2009.

Kye S.-H.,Seoul National University
Journal of Physics A: Mathematical and Theoretical | Year: 2015

We construct three-qubit entanglement witnesses with the full spanning property, by which we mean that all the partial transposes have the spanning properties. These witnesses determine faces for separable states whose interior lies in the interior of positive partial transposes (PPT) states, and so they detect sets of PPT entangled states with nonempty interiors. These witnesses also detect fully bi-separable states as well as all kinds of bi-separable pure product states. Our construction depends on the observation that multi-partite entanglement witnesses correspond to positive multi-linear maps. © 2015 IOP Publishing Ltd.

We propose novel exponentially-converging distributed flocking and formation-centroid backstepping control frameworks for multiple under-actuated thrust-propelled vehicles in SE(3), each consisting of the under-actuated Cartesian dynamics on E(3) with one-dimensional thrust-force input and the fully-actuated attitude kinematics on SO(3) with angular-rates inputs; and evolving on a strongly-connected balanced information graph G. Simulations are also performed to illustrate the theory. © 2012 Elsevier Ltd. All rights reserved.

Lee H.S.,Seoul National University
Cell and Tissue Research | Year: 2012

In patients with progressive podocyte disease, such as focal segmental glomerulosclerosis (FSGS) and membranous nephropathy, upregulation of transforming growth factor-β (TGF-β) is observed in podocytes. Mechanical pressure or biomechanical strain in podocytopathies may cause overexpression of TGF-β and angiotensin II (Ang II). Oxidative stress induced by Ang II may activate the latent TGF-β, which then activates Smads and Ras/extracellular signal-regulated kinase (ERK) signaling pathways in podocytes. Enhanced TGF-β activity in podocytes may lead to thickening of the glomerular basement membrane (GBM) by overproduction of GBM proteins and impaired GBM degradation in podocyte disease. It may also lead to podocyte apoptosis and detachment from the GBM, and epithelialmesenchymal transition (EMT) of podocytes, initiating the development of glomerulosclerosis. Furthermore, activated TGF-β/Smad signaling by podocytes may induce connective tissue growth factor and vascular endothelial growth factor overexpression, which could act as a paracrine effector mechanism on mesangial cells to stimulate mesangial matrix synthesis. In proliferative podocytopathies, such as cellular or collapsing FSGS, TGF-β-induced ERK activation may play a role in podocyte proliferation, possibly via TGF-β-induced EMT of podocytes. Collectively, these data bring new mechanistic insights into our understanding of the TGF-β overexpression by podocytes in progressive podocyte disease. © The Author(s) 2011.

Ilorme F.,Seoul National University | Griffis V.W.,Michigan Technological University
Journal of Hydrology | Year: 2013

Regional flood frequency techniques are widely used to estimate flood quantiles when flow data is unavailable for the basin under study or the record length is insufficient for reliable analyses. Data from nearby gauged sites are pooled to compensate for the lack of at-site data. This requires the delineation of hydrologically homogeneous regions in which the flood regime is sufficiently similar to allow the spatial transfer of information. It is generally accepted that hydrologic similarity results from similarity among basins' physiographic characteristics, and thus these characteristics can be used to delineate regions and classify ungauged sites. However, as currently practiced, the delineation is highly subjective and dependent on the similarity measures and classification techniques employed. Herein, a novel procedure for region delineation is proposed and evaluated using data for sites across the Southeastern United States. Key components of this procedure are a new statistical metric to identify physically discordant sites and a new methodology to identify the physical attributes that are the most indicative of extreme hydrologic response. The novel approach for region delineation is shown to produce regions which are more homogeneous and more efficient for quantile estimation at ungauged sites than those delineated using alternative physically-based procedures typically employed in practice. In addition, the identified physical attributes can be used to infer the flood regime and estimate quantiles at sites outside the extent of the area used for model development. © 2013 Elsevier B.V.

The roles of arachidonic acid (AA) metabolites in hypoxia-induced pulmonary vasoconstriction (HPV), a critical physiological mechanism that prevents ventilation/perfusion mismatch, are still incompletely understood. Pulmonary arterial pressure was measured in ventilated/perfused rat lungs. Isometric tones of rat intralobar pulmonary arteries were also measured, using a myograph. Hypoxia (Po, 3%)-induced pulmonary arterial pressure increases (ΔPAP(hypox)) were stable with blood-mixed perfusate, but decayed spontaneously. ΔPAP(hypox) was inhibited by 29%, 16%, and 28% by the thromboxane A (TXA) antagonist SQ-29548, the 5-lipoxygenase inhibitor, MK886, and the leukotriene D antagonist, LY-171883, respectively. The prostacyclin synthase inhibitor tranylcypromine augmented ΔPAP(hypox) by 5%, whereas inhibition of cytochrome P450 did not affect ΔPAP(hypox). Consistently, the TXA analogue U46619 increased ΔPAP(hypox) whereas prostacyclin abolished ΔPAP(hypox). However, leukotriene D had no direct effect on ΔPAP(hypox). In the isolated pulmonary arteries, pretreatment with U46619 was essential to demonstrate hypoxia-induced contraction. The above results suggest that TXA and cysteinyl leukotrienes, other than leukotriene D, are endogenous factors that facilitate HPV in rats. The indispensable role of TXA-induced pretone in the HPV of isolated pulmonary arteries indicates that the signal from thromboxane receptors might be a critical component of oxygen sensation mechanisms.

Huang B.,National Renewable Energy Laboratory | Xiang H.,Fudan University | Yu J.,Seoul National University | Wei S.-H.,National Renewable Energy Laboratory
Physical Review Letters | Year: 2012

Developing approaches to effectively control the charge and magnetic states is critical to the use of magnetic nanostructures in quantum information devices but is still challenging. Here we suggest that the magnetic and charge states of transition-metal (TM) doped single-layer boron-nitride (SLBN) systems can be easily controlled by the (internal) defect engineering and (external) electric fields (E ext). The relative positions and symmetries of the in-gap levels induced by defect engineering and the TM d-orbital energy levels effectively determine the charge states and magnetic properties of the TM/SLBN system. Remarkably, the application of an E ext can easily control the size of the crystal field splitting of the TM d orbitals and thus, leading to the spin crossover in TM/SLBN, which could be used as E ext-driven nonvolatile memory devices. Our conclusion obtained from TM/SLBN is valid generally in other TM adsorbed layered semiconductors. © 2012 American Physical Society.

Min K.,Korea Institute of Science and Technology | Yoo Y.J.,Seoul National University
Biotechnology and Bioprocess Engineering | Year: 2014

Recent advances in nanotechnology have provided various nanoscale materials that can be used as support for enzyme immobilization. Nanobiocatalysis integrating the biocatalyst and nanoscale materials is drawing great attention as innovative technology. Nanobiocatalysis could achieve not only a much higher enzyme loading capacity and a significantly enhanced mass transfer efficiency, but also unbelievable stabilization. In this review, we will present and discuss the recent progress in nanobiocatalysis and its applications in the fields of bioelectronics, bioconversion, and proteomics. © 2014 The Korean Society for Biotechnology and Bioengineering and Springer-Verlag Berlin Heidelberg.

Jang H.C.,Seoul National University
Diabetes and Metabolism Journal | Year: 2011

Korean women with a history of gestational diabetes mellitus (GDM) have a 3.5 times greater risk of developing postpartum diabetes than the general population. The incidence of type 2 diabetes mellitus in early postpartum is reported as 10-15% in Korean women. A prospective follow-up study on Korean women with GDM showed that approximately 40% of women with previous GDM were expected to develop diabetes within 5 years postpartum. Independent risk factors for the development of diabetes in Korean women with previous GDM are pre-pregnancy body weight, gestational age at diagnosis, antepartum hyperglycemia on oral glucose tolerance test, low insulin response to oral glucose load, and family history of diabetes. Women with postpartum diabetes have greater body mass indexes, body weight, and waist circumferences than women with normal glucose tolerance. Multiple logistic regression analysis has revealed that waist circumference is the strongest obesity index along with systolic blood pressure and that triglyceride levels are a major independent risk factor for developing diabetes. These results in Korean women with previous GDM underline the importance of postpartum testing in Korean women diagnosed with GDM, and demonstrate that impaired B-cell function, obesity, and especially visceral obesity, are associated with the development of diabetes. © 2011 Korean Diabetes Association.

Wiggins K.M.,University of Texas at Austin | Brantley J.N.,University of Texas at Austin | Bielawski C.W.,University of Texas at Austin | Bielawski C.W.,Seoul National University
Chemical Society Reviews | Year: 2013

Mechanically responsive polymers harness mechanical energy to facilitate unique chemical transformations and bestow materials with force sensing (e.g., mechanochromism) or self-healing capabilities. A variety of solution- and solid-state techniques, covering a spectrum of forces and strain rates, can be used to activate mechanically responsive polymers. Moreover, many of these methods have been combined with optical spectroscopy or chemical labeling techniques to characterize the products formed via mechanical activation of appropriate precursors in situ. In this tutorial review, we discuss the methods and techniques that have been used to supply mechanical force to macromolecular systems, and highlight the advantages and challenges associated with each. © 2013 The Royal Society of Chemistry.

Kim J.A.,Seoul National University
Integrative biology : quantitative biosciences from nano to macro | Year: 2012

In order to successfully utilize stem cells for therapeutic applications in regenerative medicine, efficient differentiation into a specific cell lineage and guidance of axons in a desired direction is crucial. Here, we used aligned multi-walled carbon nanotube (MWCNT) sheets to differentiate human mesenchymal stem cells (hMSCs) into neural cells. Human MSCs present a preferential adhesion to aligned CNT sheets with longitudinal stretch parallel to the CNT orientation direction. Cell elongation was 2-fold higher than the control and most of the cells were aligned on CNT sheets within 5° from the CNT orientation direction. Furthermore, a significant, synergistic enhancement of neural differentiation was observed in hMSCs cultured on the CNT sheets. Axon outgrowth was also controlled using nanoscale patterning of CNTs. This CNT sheet provides a new cellular scaffold platform that can regulate morphogenesis and differentiation of stem cells, which could open up a new approach for tissue and stem cell regeneration.

Baek S.,Seoul National University
Molecular Cell | Year: 2011

Signaling pathways involve cascades of protein phosphorylation and ultimately affect regulation of transcription in the nucleus. However, most of the kinases in these pathways have not been generally considered to directly modulate transcription thus far. Here, recent significant progress in the field elucidating direct modifications of histones and histone modifiers by upstream kinases is summarized, and future directions are discussed. © 2011 Elsevier Inc.

Kim Y.M.,Seoul National University
Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology | Year: 2011

Hepatitis B virus (HBV) infection can be associated with non-Hodgkin's lymphoma (NHL), and prophylactic antiviral therapy is recommended for NHL patients with chronic HBV infection who are receiving anticancer chemotherapy. The aims of this study were to investigate the association between HBV infection and NHL, and to evaluate the application rate and the effect of prophylactic antiviral therapy for HBV-infected NHL patients. A retrospective, case-control study was performed. The prevalence of hepatitis B surface antigen in 344 patients who were consecutively diagnosed with NHL from May 2003 to October 2009 (44 of 344; 12.8%) was significantly higher than that of 688 age- and sex-matched health-check examinees (24 of 688; 3.5%) (adjusted odds ratio, 4.08; 95% confidence interval, 2.44-6.85). T cell type NHL, as well as B cell type, showed a significant association with HBV carrier rate. Among 32 NHL patients who received anticancer chemotherapy, 30 patients (93.8%) received prophylactic antiviral therapy, primarily lamivudine. However, HBV DNA monitoring during antiviral therapy was frequently omitted in hemato-oncology clinics. While there was no occurrence of hepatitis flare during antiviral therapy, withdrawal hepatitis after discontinuation of antiviral drug occurred frequently (60%). HBV may play a significant role in development of NHL, which prompts further study on the lymphomagenic mechanism of HBV infection. Prophylactic antiviral therapy was administered during chemotherapy to almost all of the NHL patients with HBV infection; however, further investigation should be conducted for determination of optimal duration and monitoring of antiviral therapy. Copyright © 2011 Elsevier B.V. All rights reserved.

Radogna F.,Laboratoire Of Biologie Moleculaire Et Cellulaire Du Cancer | Dicato M.,Laboratoire Of Biologie Moleculaire Et Cellulaire Du Cancer | Diederich M.,Seoul National University
Biochemical Pharmacology | Year: 2015

Cell death plays an essential role in the development of organs, homeostasis, and cancer. Apoptosis and programmed necrosis are two major types of cell death, characterized by different cell morphology and pathways. Accumulating evidence shows autophagy as a new alternative target to treat tumor resistance. Besides its well-known pro-survival role, autophagy can be a physiological cell death process linking apoptosis and programmed necrosis cell death pathways, by various molecular mediators.Here, we summarize the effects of pharmacologically active compounds as modulators of different types of cancer cell death depending on the cellular context. Indeed, current findings show that both natural and synthetic compounds regulate the interplay between apoptosis, autophagy and necroptosis stimulating common molecular mediators and sharing common organelles. In response to specific stimuli, the same death signal can cause cells to switch from one cell death modality to another depending on the cellular setting.The discovery of important interconnections between the different cell death mediators and signaling pathways, regulated by pharmacologically active compounds, presents novel opportunities for the targeted treatment of cancer. The aim of this review is to highlight the potential role of these compounds for context-specific anticancer therapy. © 2015 Elsevier Inc.

Lee K.W.,Konkuk University | Lee K.W.,Seoul National University | Bode A.M.,University of Minnesota | Dong Z.,University of Minnesota
Nature Reviews Cancer | Year: 2011

Although successful for a limited number of tumour types, the efficacy of cancer therapies, especially for late-stage disease, remains poor overall. Many have argued that this could be avoided by focusing on cancer prevention, which has now entered the arena of targeted therapies. During the process of identifying preventive agents, dietary phytochemicals, which are thought to be safe for human use, have emerged as modulators of key cellular signalling pathways. The task now is to understand how these chemicals perturb these pathways by modelling their interactions with their target proteins. © 2011 Macmillan Publishers Limited. All rights reserved.

Kim B.-J.,Seoul National University
World Journal of Gastroenterology | Year: 2014

Hepatitis B virus (HBV) infection is a global health problem and more than 350 million people worldwide are chronic carriers of the virus. Despite the recent dramatic decline in HBV chronic patients through successful programs of hepatitis B surface antigen vaccination, South Korea is still recognized as an endemic area of HBV infection. HBV infections in South Korea exhibit several distinct features in epidemiologic and clinical aspects. In this review paper, we summarize the distinct HBV mutation patterns related to clinical severity and the molecular epidemiologic traits in Korean chronic patients based on previous reports. Generally, several lines of evidence, including our previous results, have led to the conclusion that a combination of the exclusive predominance of genotype C2, which is prone to mutations, the high prevalence of basal core promoter double mutations, and the presence of distinct immune responses against HBV proteins in the Korean population may generate the distinct HBV variants rarely or not encountered in other areas, which results in distinct clinical manifestations in Korean chronic patients. This may provide a novel insight into the relationships between clinical severity, HBV genotype distribution, and HBV naturally occurring variants. © 2014 Baishideng Publishing Group Co., Limited. All rights reserved.

Lee M.-G.,Pohang University of Science and Technology | Kim S.-J.,Korea Institute of Materials Science | Han H.N.,Seoul National University
International Journal of Plasticity | Year: 2010

A new crystal plasticity model incorporating the mechanically induced martensitic transformation in metastable austenitic steel has been formulated and implemented into the finite element analysis. The kinetics of martensite transformation is modeled by taking into consideration of a nucleation-controlled phenomenon, where each potential martensitic variant based on Kurdjumov-Sachs (KS) relationship has different nucleation probability as a function of the interaction energy between externally applied stress and lattice deformation. Therefore, the transformed volume fractions are determined following selective variants given by the crystallographic orientation of austenitic matrix and applied stress in the frame of the crystal plasticity finite element. The developed finite element program is capable of considering the effect of volume change by the Bain deformation and the lattice-invariant shear during the martensitic transformation by effectively modifying the evolution of plastic deformation gradient of the conventional rate-dependent crystal plasticity finite element. The validation of the proposed model has been carried out by comparing with the experimentally measured data under simple loading conditions. Good agreements with the measurements for the stress-strain responses, transformed martensitic volume fractions and the influence of strain rate on the deformation behavior will enable the model to be promising for the future applications to the real forming process of the TRIP aided steel. © 2009 Elsevier Ltd. All rights reserved.

Jang B.S.,Korea Institute of Water and Environment | Oh B.H.,Seoul National University
Cement and Concrete Research | Year: 2010

The purpose of this study is to explore the effects of non-uniform corrosion on cracking behavior of concrete cover. The effects of non-uniform corrosion distribution, cover-to-rebar diameter ratio, and concrete compressive strength on the cracking pressure of concrete cover were studied. The present study indicates that the pressures to cause cracking of concrete cover under non-uniform corrosion conditions are much smaller than those under uniform corrosion case. The cracking pressure decreases up to about 60% depending upon the types of non-uniform corrosion distributions. It was also shown that cover-to-rebar diameter ratio and concrete compressive strength affect greatly the cracking pressure of concrete cover. Realistic equations on the cracking pressure of concrete cover were derived. The comparisons of analysis results with the test data on the cracking pressure of concrete cover show fairly good agreement. Finally, the effect of non-uniform corrosion on the service life of concrete structures was discussed. © 2010 Elsevier Ltd. All rights reserved.

Jeong H.E.,University of California at Berkeley | Suh K.-Y.,Seoul National University
Soft Matter | Year: 2012

We present a simple, yet robust, technique for controlling the tip geometry of nanopillars by utilizing a two-step process of partial photopolymerization of UV-curable polyurethane acrylate (PUA) resin and subsequent tip shape modification. With this technique, head structures of nanopillars were precisely transformed from hemispherical to protruding, mushroom-like tips without any loss in structural integrity of the nanopillars. Nanoscopic and macroscopic adhesion measurements for angled nanopillars with modified tips demonstrated that mushroom-like structures fabricated by our approach could greatly enhance adhesion strengths as compared to unmodified, round head structures. Also, directional adhesion characteristics of angled nanopillars were maintained regardless of tip shapes. © 2012 The Royal Society of Chemistry.

Kang S.B.,Seoul National University
Diseases of the colon and rectum | Year: 2010

BACKGROUND: Laparoscopy-assisted surgery has technical drawbacks compared with open surgery, although laparoscopic surgery has become widely adopted with evidence of oncological safety for colon cancer treatment. The oncological risk of technical difficulties during laparoscopic surgery for colorectal cancer has not been previously reported. We aimed to investigate whether a technical difficulty encountered during laparoscopic surgery can be considered a recurrence-related factor for colorectal cancer. METHODS: Data from 427 patients who underwent laparoscopic surgery for colorectal cancer between May 2003 and December 2007 were analyzed. An intraoperative technical difficulty was defined as a significant deviation from the ordinary surgical procedure. All conversions to open surgery and iatrogenic bowel perforation during laparoscopic surgery were included as technical difficulties. The Cox proportional-hazards regression model was used to evaluate the recurrence-related factor in the various risk factors including technical difficulty. RESULTS: Technical difficulties were found in 44 (10.3%) patients, which included 17 (3.9%) conversions to open surgery and 10 (2.4%) with iatrogenic bowel injury. Technical difficulties were encountered more frequently in men compared with women (13.5% vs 6.0%, P = .013), and for cancers located in the mid and low rectum, splenic flexure, and descending colon. The recurrence rates were higher in patients with technical difficulties (local recurrence, 2.6% vs 6.7%, P < .05; systemic recurrence, 6.3% vs 13.6%, P < .05) with a mean follow-up duration of 45.9 months. Multivariate analysis by the Cox proportional-hazards regression model showed that a technical difficulty was an independent factor related to recurrence after laparoscopic surgery (odds ratio, 2.374; 95% CI, 1.006-5.600; P = .048). CONCLUSIONS: This study has demonstrated that a technical difficulty during laparoscopy-assisted surgery jeopardizes oncological safety. It is suggested that surgeons should be prepared to minimize technical difficulties during laparoscopy-assisted surgery.

For successful implantation and establishment of early epitheliochorial placentation, porcine conceptuses require histotroph, including nutrients and growth factors, secreted by or transported into the lumen of the uterus. Epidermal growth factor (EGF), an essential component of histotroph, is known to have potential growth-promoting activities on the conceptus and uterine endometrium. However, little is known about its effects to transactivate cell signaling cascades responsible for proliferation, growth and differentiation of conceptus trophectoderm. In the present study, therefore, we determined that EGFR mRNA and protein were abundant in endometrial luminal and glandular epithelia, stratum compactum stroma and conceptus trophectoderm on days 13-14 of pregnancy, but not in any other cells of the uterus or conceptus. In addition, primary porcine trophectoderm (pTr) cells treated with EGF exhibited increased abundance of phosphorylated (p)-AKT1, p-ERK1/2 MAPK and p-P90RSK over basal levels within 5min, and effect that was maintained to between 30 and 120min. Immunofluorescence microscopy revealed abundant amounts of p-ERK1/2 MAPK and p-AKT1 proteins in the nucleus and, to a lesser extent, in the cytoplasm of pTr cells treated with EGF as compared to control cells. Furthermore, the abundance of p-AKT1 and p-ERK1/2 MAPK proteins was inhibited in control and EGF-treated pTr cells transfected with EGFR siRNA. Compared to the control siRNA transfected pTr cells, pTr cells transfected with EGFR siRNA exhibited an increase in expression of IFND and TGFB1, but there was no effect of expression of IFNG. Further, EGF stimulated proliferation and migration of pTr cells through activation of the PI3K-AKT1 and ERK1/2 MAPK-P90RSK cell signaling pathways. Collectively, these results support the hypothesis that EGF coordinately activates multiple cell signaling pathways critical to proliferation, migration and survival of trophectoderm cells that are critical to development of porcine conceptuses during implantation and placentation. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Mesenchymal stem cells (MSCs) promote therapeutic angiogenesis to cure serious vascular disorders. However, their survival period and cytokine-secretory capacity are limited. Although hepatocyte growth factor (HGF) can accelerate the rate of angiogenesis, recombinant HGF is limited because of its very short half-life (<3–5 minutes). Thus, continuous treatment with HGF is required to obtain an effective therapeutic response. To overcome these limitations, we produced genome-edited MSCs that secreted HGF upon drug-specific induction. The inducible HGF expression cassette was integrated into a safe harbor site in an MSC chromosome using the TALEN system, resulting in the production of TetOn-HGF/human umbilical cord blood-derived (hUCB)-MSCs. Functional assessment of the TetOn-HGF/hUCB-MSCs showed that they had enhanced mobility upon the induction of HGF expression. Moreover, long-term exposure by doxycycline (Dox)-treated TetOn-HGF/hUCB-MSCs enhanced the anti-apoptotic responses of genome-edited MSCs subjected to oxidative stress and improved the tube-formation ability. Furthermore, TetOn-HGF/hUCB-MSCs encapsulated by arginine-glycine-aspartic acid (RGD)-alginate microgel induced to express HGF improved in vivo angiogenesis in a mouse hindlimb ischemia model. This study showed that the inducible HGF-expressing hUCB-MSCs are competent to continuously express and secrete HGF in a controlled manner. Thus, the MSCs that express HGF in an inducible manner are a useful therapeutic modality for the treatment of vascular diseases requiring angiogenesis.Molecular Therapy (2016); doi:10.1038/mt.2016.120. © 2016 American Society of Gene & Cell Therapy

Lee C.,Seoul National University
Journal of Health Economics | Year: 2014

Prenatal exposure to the disruptions caused by the Korean War (1950-1953) negatively affected the individual socioeconomic and health outcomes at older ages. The educational attainment, labor market performance, and other socioeconomic outcomes of the subjects of the 1951 birth cohort, who were in utero during the worst time of the war, were significantly lower in 1990 and in 2000. The results of difference-in-difference estimations suggest that the magnitude of the negative cohort effect is significantly larger for individuals who were more seriously traumatized by the war. Whereas the 1950 male birth cohort exhibited significantly higher disability and mortality rates at older age, the health outcomes of females are unaffected by the war. Different aspects of human capital (e.g., health and cognitive skills) were impaired by in utero exposure to the war, depending on the stage of pregnancy when the negative shocks were experienced. © 2013 Elsevier B.V.

Schnekenburger M.,Laboratoire Of Biologie Moleculaire Et Cellulaire Du Cancer | Dicato M.,Laboratoire Of Biologie Moleculaire Et Cellulaire Du Cancer | Diederich M.,Seoul National University
Biotechnology Advances | Year: 2014

Carcinogenesis is a complex and multistep process that involves the accumulation of successive transformational events driven by genetic mutations and epigenetic alterations that affect major cellular processes and pathways such as proliferation, differentiation, invasion and survival. Massive deregulation of all components of the epigenetic machinery is a hallmark of cancer. These alterations affect normal gene regulation and impede normal cellular processes including cell cycle, DNA repair, cell growth, differentiation and apoptosis. Since epigenetic alterations appear early in cancer development and represent potentially initiating events during carcinogenesis, they are considered as promising targets for anti-cancer interventions by chemopreventive and chemotherapeutic strategies using epigenetically active agents. In this field, plant-derived compounds have shown promise. Here, we will give an overview of plant-derived compounds displaying anticancer properties that interfere with the epigenetic machinery. © 2014 Elsevier Inc.

Kim K.M.,Seoul National University | Lim S.-K.,Yonsei University
Current Opinion in Pharmacology | Year: 2014

MicroRNAs (miRNAs) are noncoding, single-stranded RNAs that regulate the expression of target genes by binding their 3′-untranslated region. miRNAs are important regulators of various biological processes, including cellular differentiation, proliferation, apoptosis, and tissue development. Furthermore, aberrant miRNA expression has emerged as an important pathomechanism in various human diseases, including osteoporosis. Thus, the therapeutic potential of miRNA has attracted great interest recently. Here, we focused on the roles of miRNAs in bone homeostasis and the potential of miRNAs as therapeutic targets. © 2014 Elsevier Ltd.

Kim J.G.,Seoul National University
Journal of Ecology and Field Biology | Year: 2012

Litterfall dynamics in forests are assessed by estimating biomass production and decomposition. However, there have been few studies on how litter dynamics impact the health and management of ecosystems. Here, a new approach to measure and assess ecosystem function is presented based on conventional methods using littertraps, litterbags, and the mass on the forest floor. To assess the status of litter dynamics, the decay rate (k) was estimated from a litterbag experiment, and removal rates (ki) were determined from mass balance on the forest floor at 21 sites on three mountains in South Korea. The k3 (organic mass ratio of Oi and Oe + Oa + A horizons in November) values in an equilibrium state in South Korea were within the range of k ± 0.174 when considering the annual variation of litterfall production. This study also suggests that sampling sites for these types of studies should be in the middle, not at the ends, of steady slopes on the forest floor. © The Ecological Society of Korea.

Kim J.,Samsung | Cho B.H.,Seoul National University
IEEE Transactions on Energy Conversion | Year: 2013

This paper investigates the application of the dual extended Kalman filter (DEKF) algorithm combined with the pattern recognition based on the Hamming network (HN) to the identification of suitable cell model parameters for improved state-of-charge (SOC)/capacity estimation at different temperatures. The averaged nine discharging/charging voltage-temperature (DCVT) patterns for 10 fresh Li-ion cells were measured at different temperatures, together with the cell parameters, as representative patterns. Through statistical analysis of the characteristic parameters for learning by the HN, the identification of the representative DCVT pattern that most closely matches that of the arbitrary cell to be measured at any temperature. Specifically, a detailed temperature is obtained by the temperature-checking process and is added or reduced according to representative DCVT pattern discriminated. Finally, appropriate model parameters from the proposed approach are determined and used for SOC/capacity estimation in DEKF. © 1986-2012 IEEE.

The radioactive material dispersion is investigated in terms of the radioactive concentrations. The risk of the radioactive hazard material is important with respect to the public health. The prevailing westerlies region is modeled for the dynamical consequences, whereby the Fukushima nuclear disaster in Japan is modeled. The multiplications effects of the wind values and plume concentrations are obtained. Monte Carlo calculations are performed for wind speed and direction. In Seoul and Pusan, Korea, the Cs-137 has the highest value among the chemical radioactive materials Cs-137, I-131, and Sr-90. The time for highest concentration is shown to be around 48th hour in Seoul and 12th hour in Pusan. Cesium has the highest value in both cities, and iodine has the lowest value in both cities. The wind is assumed to determine the direction of movement. Therefore, the real values are believed to be lower than the calculated results. This modeling could be used for other industrial accident cases in chemical plants. © 2012 Elsevier Ltd. All rights reserved.

Lee H.S.,Seoul National University
Histology and Histopathology | Year: 2011

In patients with progressive podocyte diseases, such as focal segmental glomerulosclerosis and membranous nephropathy, there is enhanced expression of transforming growth factor (TGF-ß) in podocytes. Biomechanical strain in these diseases may cause overexpression of TGF-ß and angiotensin II (Ang II) by podocytes. Oxidative stress induced by Ang II may activate the latent TGF-ß. Increased TGF-ß activity by podocytes may induce not only the thickening of the glomerular basement membrane (GBM), but also podocyte apoptosis and/or detachment from the GBM, initiating the development of glomerulosclerosis. Furthermore, mesangial matrix expansion frequently occurs in podocyte diseases in association with the development of glomerulosclerosis. This review examines open questions on the pathogenic role of TGF-ß that links podocyte injury to GBM thickening, podocyte loss, mesangial matrix expansion and glomerulosclerosis in podocyte diseases. It also describes paracrine regulatory mechanisms of podocyte TGF-ß on mesangial cells leading to increased matrix synthesis.

We investigated the mechanisms of action and antitumor effects of OPB-31121, a novel STAT3 inhibitor, in gastric cancer cells. OPB-31121 downregulated JAK2 and gp130 expression and inhibited JAK2 phosphorylation which leads to inhibition of STAT3 phosphorylation. OPB-31121 inhibited constitutively activated and IL-6-induced JAK/STAT signaling pathway. OPB-31121 decreased cell proliferation in both gastric cancer cells and in a xenograft model, induced the apoptosis of gastric cancer cells, inhibited the expression of antiapoptotic proteins, and showed synergism with 5-fluorouracil and cisplatin. Taken together, our study suggests that STAT3 inhibition with OPB-31121 can be tested in patients with gastric cancer. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Chon I.,Seoul National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2013

Eradication of Helicobacter pylori reduces the incidence of gastric cancer, and may inhibit gastric dysplasia progression into gastric cancer. The aim of this study was to investigate the effect of eradication of Helicobacter on the incidence of subsequent gastric dysplasia development after endoscopic resection. Medical records of patients who underwent endoscopic resection for gastric dysplasia were retrospectively reviewed. Presence of H. pylori was assessed by the Campylobacter-like organism test and histology. The rate of subsequent dysplasia development after endoscopic resection between the eradication group and non-eradication group was compared. Total of 129 patients positive for H. pylori infection were included for analysis. Of these, 85 patients received successful eradication therapy and 44 patients did not receive eradication therapy or failed to achieve successful eradication. Sex, mean age and pathologic grade of dysplasia did not differ between the two groups. In univariate analysis, the grade of intestinal metaplasia (p=0.013) significantly differed between metachronous dysplasia group and non-metachrounous dysplasia group. In multivariate analysis, eradication of H. pylori (p=0.014) was related to reduced incidence of subsequent gastric dysplasia development after endoscopic resection. Eradication of H. pylori likely has a beneficial effect in preventing the development of subsequent gastric dysplasia, a premalignant lesion of gastric cancer, after endoscopic resection.

Lee J.W.,Seoul National University
Journal of endourology / Endourological Society | Year: 2013

Abstract Purpose: To evaluate surgical outcomes of laparoscopic pyelolithotomy (LP) in relation to stone distribution within the kidney. Methods: Between August 2008 and February 2012, 77 patients underwent LP as first-line treatment for renal stone(s). Cases were classified into four groups, depending on stone location: Group I (located in only renal pelvis), Group II (located only in renal calyx), Group III (located in renal pelvis and in one calyx), and Group IV (located in renal pelvis and in multiple calyces). Patient and stone characteristics, surgical outcomes, and complications were evaluated. Results: Sixty-seven (81.8%) cases were stone-free after LP for large renal stones. Stone-free rates in a single session significantly decreased with greater stone dispersion (p<0.001). Mean hospital stay in group IV was significantly longer than in other groups (p=0.038). However, there were no significant differences in mean operation times (p=0.214), mean change in serum hemoglobin (p=0.709), postoperative analgesics usages (p=0.153), and number of analgesics used on an as-needed basis (p=0.079). There were no complications of grade IIIb or of greater severity. One patient in group II received blood transfusion, and 1 in group III required percutaneous drainage due to perirenal urine collection. Conclusions: LP is an effective and safe modality for managing renal stones diseases. Distribution of stone burden, and total stone burden, is an important predictor of surgical outcome of LP in renal stone diseases.

Inflammatory pseudotumor (IPT)-like follicular dendritic cell (FDC) sarcoma is a rare neoplasm typically occurring in the spleen or liver. We present six cases of EBV(+) IPT-like FDC sarcoma of the spleen among Koreans along with their clinicopathologic features and IHC results. Most patients presented with an asymptomatic, incidentally detected single splenic mass and were successfully managed by splenectomy alone. Concomitant disease was found in one case, showing EBV(+) gastric carcinoma with lymphoid-rich stroma. Histologic features showed fibro-inflammatory lesions that were often accompanied by necrosis and epithelioid histiocytic collection, which are barely distinguishable from IPT. Tumor cells did not frequently express conventional FDC markers, including CD21 (3/6 positive cases), clusterin (4/6), and D2-40 (2/6), but showed uniform positivity for smooth muscle actin (SMA). Noticeably, significant numbers of IgG4(+) plasma cells were found within all six tumors. We suggest that the diagnosis of IPT-like FDC sarcoma should be made by the application of a panel of FDC markers, and CD21 negativity or SMA positivity cannot be the criterion for exclusion of IPT-like FDC sarcoma. Relationship of IPT-like FDC sarcoma of the spleen and IgG4-related sclerosing disease should be investigated in further studies. © 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.

Hong S.-T.,Seoul National University | Fang Y.,U.S. Center for Disease Control and Prevention
Parasitology International | Year: 2012

Clonorchis sinensis is the most common human liver fluke in East Asia. Several studies proved its carcinogenesis in humans and it was reclassified as a group 1 biological carcinogen in 2009. It is still actively transmitted in endemic areas of Korea, China, Russia, and Vietnam. Currently it is estimated that more than 200 million people are at risk of infection, 15-20 million people are infected and 1.5-2 million show symptoms or complications. Several molecules and genes of the fluke have been identified and characterized. Studies on its oncogenesis and omics-based findings have been especially encouraging. Diagnosis of its infection depends mainly on detection of eggs in feces but other methods have been developed. ELISA using crude extract antigen is now popular for its diagnosis. Diagnosis by detecting DNAs from eggs in feces has been developed using PCR, real-time PCR, and LAMP, which have been found sensitive and specific. Imaging diagnosis has been studied in depth and is widely used. Any evidence of clonorchiasis, such as eggs, DNAs, or images, may lead to recommendations of chemotherapy in endemic areas. Praziquantel is the major chemotherapeutic agent for clonorchiasis and recently tribendimidine was found effective and is now under investigation as a promising chemotherapeutic alternative. Sustainable control programs which include mass chemotherapy with praziquantel and education for prevention of re-infection may reduce its morbidity and eliminate its infections in endemic areas. © 2011 Elsevier Ireland Ltd.

Ahn H.-R.,Seoul National University
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

In the above paper, the high-low impedance (HLI) section and its characteristic impedance of ZHLI are suggested to reduce the size of branch-line and rat-race couplers. The characteristic impedance of Z HLI, however, appears to be incorrect for the application of the asymmetric structures, such as the HLI sections. © 1963-2012 IEEE.

Choi T.H.,Seoul National University
Plastic and Reconstructive Surgery | Year: 2013

BACKGROUND: Following injury, Asian skin has a tendency towards hyper-pigmentation and scar formation, and therefore the prevention of scarring is particularly important in Asian patients. Since publication of an International Clinical Recommendation on Scar Management in 2002, there have been numerous publications in the field of scar management. Advances in understanding scar formation have also led to the introduction of new treatments as well as a better understanding of established therapeutic options. METHODS: A literature search for abstracts, clinical trials and meta-analyses evaluating scar prevention and treatment was performed using PubMed and the Cochrane Database of Systematic Reviews. Based on this data a panel of experts formulated treatment recommendations for Asian patients. RESULTS: Following surgery, scar prevention should be initiated in all Asian patients due to the high risk of poor scars. There is strong evidence for the efficacy of silicone based products, and due to their ease of use, they can be considered first-line therapy. Silicone gel (versus silicone gel sheets) products have demonstrated efficacy. For patients who fail to respond to first-line therapy, intralesional steroid injections, radiation therapy, and intralesional 5-flourouracil injections have achieved widespread acceptance. Laser treatments have been increasingly used, although the evidence remains largely anecdotal without a clear consensus on optimal wavelength, or amount of energy. Surgical approaches have increased in sophistication with recognition of the impact that tension has on scar formation. CONCLUSION: Updated scar management recommendations will benefit practitioners making decisions regarding optimal, evidence-based treatment strategies for their patients. Copyright © 2013 by the American Society of Plastic Surgeons.