The University of Science and Technology is a group of public universities and research institutions in Seoul, Suwon, Changwon, Ansan, Seongnam and Daejeon, in South Korea. The UST was established in 2003 by Korea's government as the nation’s graduate school specializing in science and engineering education and research. The UST runs only a graduate school. It is one of the top science and technology universities in South Korea along with KAIST and POSTECH. Creating the new driving force for growth would play a major role in leading national growth in the 21st century. The South Korean government established the UST to produce professionals in the field of combined technologies, thought of as one of the most important criteria for creating the driving force for South Korea's national growth. Today, UST continues to develop itself into a major research university. Wikipedia.
Lee S.-J.,Korean University of Science and Technology |
Lee S.-J.,University of California at San Francisco |
Hwang A.B.,Korean University of Science and Technology |
Kenyon C.,University of California at San Francisco
Current Biology | Year: 2010
A mild inhibition of mitochondrial respiration extends the life span of many organisms, including yeast, worms, flies, and mice [1-10], but the underlying mechanism is unknown. One environmental condition that reduces rates of respiration is hypoxia (low oxygen). Thus, it is possible that mechanisms that sense oxygen play a role in the longevity response to reduced respiration. The hypoxia-inducible factor HIF-1 is a highly conserved transcription factor that activates genes that promote survival during hypoxia [11, 12]. In this study, we show that inhibition of respiration in C. elegans can promote longevity by activating HIF-1. Through genome-wide screening, we found that RNA interference (RNAi) knockdown of many genes encoding respiratory-chain components induced hif-1-dependent transcription. Moreover, HIF-1 was required for the extended life spans of clk-1 and isp-1 mutants, which have reduced rates of respiration [1, 4, 13]. Inhibiting respiration appears to activate HIF-1 by elevating the level of reactive oxygen species (ROS). We found that ROS are increased in respiration mutants and that mild increases in ROS can stimulate HIF-1 to activate gene expression and promote longevity. In this way, HIF-1 appears to link respiratory stress in the mitochondria to a nuclear transcriptional response that promotes longevity. © 2010 Elsevier Ltd All rights reserved.
Shemorry A.,California Institute of Technology |
Hwang C.-S.,Korean University of Science and Technology |
Varshavsky A.,California Institute of Technology
Molecular Cell | Year: 2013
Nα-terminal acetylation of cellular proteins was recently discovered to create specific degradation signals termed Ac/N-degrons and targeted by the Ac/N-end rule pathway. We show that Hcn1, a subunit of the APC/C ubiquitin ligase, contains an Ac/N-degron that is repressed by Cut9, another APC/C subunit and the ligand of Hcn1. Cog1, a subunit of the Golgi-associated COG complex, is also shown to contain an Ac/N-degron. Cog2 and Cog3, direct ligands of Cog1, can repress this degron. The subunit decoy technique was used to show that the long-lived endogenous Cog1 is destabilized and destroyed via its activated (unshielded) Ac/N-degron if the total level of Cog1 increased in a cell. Hcn1 and Cog1 are the first examples of protein regulation through the physiologically relevant transitions that shield and unshield natural Ac/N-degrons. This mechanistically straightforward circuit can employ the demonstrated conditionality of Ac/N-degrons to regulate subunit stoichiometries and other aspects of protein quality control. © 2013 Elsevier Inc..
Kang S.,Korea Research Institute of Chemical Technology |
Lee H.-K.,Korean University of Science and Technology
Journal of Organic Chemistry | Year: 2010
(Chemical Equation Presented) A highly efficient, enantioselective sequence has been developed for the synthesis of (S)- and (R)-dapoxetine. The pathways involve the intermediacy of the 6-membered-ring sulfamate esters 4, which were generated by Du Bois asymmetric C-Hamination reactions of the prochiral sulfamate 3, catalyzed by the chiral dirhodium(II) complexes. During the course of our research, the absolute configuration of the enantiomer of 4-pheny[1,2,3]oxathiazinane 2,2-dioxide (4r), prepared by the Du Bois asymmetric C-H amination reaction of 3 and the Rh 2(S-nap)4 catalyst, is determined to be R and not S as was originally reported. © 2009 American Chemical Society.
Lee W.,Korea Research Institute of Standards and Science |
Lee W.,Korean University of Science and Technology |
Park S.-J.,Korea Research Institute of Standards and Science
Chemical Reviews | Year: 2014
Many desirable engineering properties such as excellent hardness, corrosion, and abrasion resistance can be obtained by anodizing aluminum metals in acid electrolytes. In addition, due to its high porosity, the porous oxide films formed on the metals serve as a good adhesion base for electroplating, painting, and semi-permanent decorative coloration. Porous AAO film grown on aluminum is composed of a thin barrier oxide layer in conformal contact with aluminum, and an overlying, relatively thick, porous oxide film containing mutually parallel nanopores extending from the barrier oxide layer to the film surface. Each cylindrical nanopore and its surrounding oxide region constitute a hexagonal cell aligned normal to the metal surface. Under specific electrochemical conditions, the oxide cells self-organize into hexagonal close-packed arrangement, forming a honeycomb-like structure.
Bae J.H.,Korean University of Science and Technology
Urology | Year: 2014
OBJECTIVE: To compare the effects of subcutaneous penile injection of basic fibroblast growth factor (bFGF)-hydrogel and intracavernous injection of human adipose-derived stem cells (h-ADSCs) on improving erectile function in a rat model of cavernous nerve injury.MATERIALS AND METHODS: Adult male Sprague-Dawley rats were randomly divided into 5 groups (n = 10 per group): age-matched control (normal group), bilateral cavernous nerve injury (BCNI group), penile subcutaneous injection of hydrogel after BCNI (hydrogel group), penile subcutaneous injection of bFGF-hydrogel after BCNI (bFGF-hydrogel group) and intracavernous injection of h-ADSCs after BCNI (ADSC group). Four weeks after the treatment, all rats underwent an erectile function test. Then, penile tissue was harvested for immunohistological analysis of bFGF, phalloidin, and cluster of differentiation (CD) 31. The cyclic guanosine monophosphate (cGMP) level of the corpus cavernosum was quantified by cGMP assay.RESULTS: From the functional test and immunohistological result, we observed that bFGF-hydrogel and h-ADSCs injection significantly elevated intracavernous pressure. The evaluation of filamentous actin content, CD31 expression, and cGMP concentration in the corpus cavernosum were meaningfully increased in the bFGF-hydrogel and ADSC groups compared with BCNI group. The bFGF released from bFGF-hydrogel prevented smooth muscle atrophy. Moreover, bFGF expression was significantly increased in bFGF-hydrogel group.CONCLUSION: The subcutaneous injection of bFGF-hydrogel prevented smooth muscle atrophy, increased the intracavernous pressure, and improved erectile function like an intracavernous injection of h-ADSCs. Copyright © 2014. Published by Elsevier Inc.
Seon K.-I.,Korea Astronomy and Space Science Institute |
Seon K.-I.,Korean University of Science and Technology
Astrophysical Journal Letters | Year: 2012
Fractional Brownian motion structures are used to investigate the dependency of column density variance (σ2 ln N ) in the turbulent interstellar medium on the variance of three-dimensional density (σ2 ln ρ) and the power-law slope of the density power spectrum. We provide quantitative expressions to infer the three-dimensional density variance, which is not directly observable, from the observable column density variance and spectral slope. We also investigate the relationship between the column density variance and sonic Mach number (M s) in the hydrodynamic (HD) regime by assuming the spectral slope and density variance to be functions of sonic Mach number, as obtained from the HD turbulence simulations. They are related by the expression σ2 ln N = Aσln ρ 2 = Aln (1 + b 2 M 2 s), suggested by Burkhart & Lazarian for the magnetohydrodynamic case. The proportional constant A varies from ≈0.2 to ≈0.4 in the HD regime as the turbulence forcing parameter b increases from 1/3 (purely solenoidal forcing) to 1 (purely compressive forcing). It is also discussed that the parameter A is lowered in the presence of a magnetic field. © 2012. The American Astronomical Society. All rights reserved.
Han H.,Korea Research Institute of Standards and Science |
Huang Z.,Jiangsu University |
Lee W.,Korea Research Institute of Standards and Science |
Lee W.,Korean University of Science and Technology
Nano Today | Year: 2014
Silicon nanostructures exhibit promising application potentials in many fields in comparison with their bulk counterpart or other semiconductor nanostructures. Therefore, the exploiting of controllable fabrication methods of silicon nanostructures, and the exploring of further applications of silicon nanostructures gain extensive attentions. In this review, recent advances in metal-assisted chemical etching of silicon, a low-cost and versatile method enabling fine control over morphology feature of silicon nanostructures, are summarized. The overview concerning the applications of silicon nanostructures in the field of energy conversion and storage, and sensors are also presented. © 2014 The Authors.
Park M.,Korea Institute of Science and Technology |
Park M.,Korean University of Science and Technology |
Shen K.,Stanford University |
Shen K.,Howard Hughes Medical Institute
EMBO Journal | Year: 2012
Wnt proteins play important roles in wiring neural circuits. Wnts regulate many aspects of neural circuit generation through their receptors and distinct signalling pathways. In this review, we discuss recent findings on the functions of Wnts in various aspects of neural circuit formation, including neuronal polarity, axon guidance, synapse formation, and synaptic plasticity in vertebrate and invertebrate nervous systems. © 2012 European Molecular Biology Organization.
Chi S.-W.,Korea Research Institute of Bioscience and Biotechnology |
Chi S.-W.,Korean University of Science and Technology
BMB Reports | Year: 2014
Reactivating the p53 pathway in tumors is an important strategy for anticancer therapy. In response to diverse cellular stresses, the tumor suppressor p53 mediates apoptosis in a transcriptionindependent and transcription-dependent manner. Although extensive studies have focused on the transcription-dependent apoptotic pathway of p53, the transcription-independent apoptotic pathway of p53 has only recently been discovered. Molecular interactions between p53 and Bcl-2 family proteins in the mitochondria play an essential role in the transcriptionindependent apoptosis of p53. This review describes the structural basis for the transcription-independent apoptotic pathway of p53 and discusses its potential application to anticancer therapy.
Subbiah R.,Korean University of Science and Technology
Journal of the Royal Society, Interface / the Royal Society | Year: 2013
Hybrids consisting of carboxylated, single-walled carbon nanotube (c-SWNT)-silver nanoparticles (AgNPs)-DNA-poly vinyl alcohol (PVA) are synthesized via sequential functionalization to mimic the theragnostic (therapy and diagnosis) system. Carboxylation of SWNT has minimized the metal impurities with plenty of -COOH groups to produce hybrid (c-SWNT-AgNPs). The hybrid is further wrapped with DNA (hybrid-DNA) and encapsulated with PVA as hybrid composite (HC). Materials were tested against human alveolar epithelial cells (A549), mouse fibroblasts cells (NIH3T3) and human bone marrow stromal cells (HS-5). The composition-sensitive physico-chemical interactions, biophysics and biomechanics of materials-treated cells are evaluated. The cell viability was improved for HC, hybrid-PVA and c-SWNT when compared with SWNT and hybrid. SWNT and hybrid showed cell viability less than 60% at high dose (40 μg ml(-1)) and hybrid-PVA and HC retained 80% or more cell viability. The treatment of hybrid nanomaterials considerably changed cell morphology and intercellular interaction with respect to the composition of materials. Peculiarly, PVA-coated hybrid was found to minimize the growth of invadopodia of A549 cells, which is responsible for the proliferation of cancer cells. Surface roughness of cells increased after treatment with hybrid, where cytoplasmic regions specifically showed higher roughness. Nanoindentation results suggest that changes in biomechanics occurred owing to possible internalization of the hybrid. The changes in force spectra of treated cells indicated a possible greater interaction between the cells and hybrid with distinct stiffness and demonstrated the surface adherence and internalization of hybrid on or inside the cells.