Korea Institute of Toxicology

Chinju, South Korea

Korea Institute of Toxicology

Chinju, South Korea

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Jung H.Y.,Gyeongnam National University of Science and Technology | Jung S.M.,Korea Institute of Toxicology | Kim D.W.,Gyeongnam National University of Science and Technology | Jung Y.J.,Northeastern University
Nanoscale | Year: 2017

The allotropic transformations of carbon provide an immense technological interest for tailoring the desired molecular structures in the scalable nanoelectronic devices. Herein, we explore the effects of morphology and geometric alignment of the nanotubes for the re-engineering of carbon bonds in the heterogeneous carbon nanotube (CNT) networks. By applying alternating voltage pulses and electrical forces, the single-walled CNTs in networks were predominantly transformed into other predetermined sp2 carbon structures (multi-walled CNTs and multi-layered graphitic nanoribbons), showing a larger intensity in a coalescence-induced mode of Raman spectra with the increasing channel width. Moreover, the transformed networks have a newly discovered sp2-sp3 hybrid nanostructures in accordance with the alignment. The sp3 carbon structures at the small channel are controlled, such that they contain up to about 29.4% networks. This study provides a controllable method for specific types of inter-allotropic transformations/hybridizations, which opens up the further possibility for the engineering of nanocarbon allotropes in the robust large-scale network-based devices. © 2017 The Royal Society of Chemistry.

Kim H.J.,Kyungpook National University | Lim J.-S.,Kyungpook National University | Kim W.-K.,Korea Institute of Toxicology | Kim J.-S.,Kyungpook National University
Proceedings of the Nutrition Society | Year: 2012

Glyceollins, one family of phytoalexins, are de novo synthesised from daidzein in the soyabean upon exposure to some types of fungus. The efficiency of glyceollin production appears to be influenced by soyabean variety, fungal species, and the degree of physical damage to the soyabean. The compounds have been shown to have strong antioxidant and anti-inflammatory activities, and to inhibit the proliferation and migration of human aortic smooth muscle cells, suggesting their potential to prevent atherosclerosis. It has also been reported that glyceollins have inhibited the growth of prostate and breast cancer cells in xenograft animal models, which is probably due to their anti-oestrogenic activity. In essence, glyceollins deserve further animal and clinical studies to confirm their health benefits. © 2011 The Authors.

Hwang Y.S.,Korea Institute of Toxicology | Qu X.,Rice University | Li Q.,Rice University
Carbon | Year: 2013

The photochemical transformation of carboxylated multiwall carbon nanotubes (COOH-MWCNTs) in water and the subsequent impact on their aggregation and deposition behaviors were examined. The photochemical transformation of COOH-MWCNTs was investigated under UVA (300-400 nm) irradiation, the main component of UV light in solar irradiation. Time-resolved dynamic light scattering measurement and quartz crystal microbalance with dissipation monitoring were used to study the initial aggregation and deposition kinetics. Characterization of the physicochemical properties of the COOH-MWCNTs before and after irradiation revealed a loss in surface oxygen after UV irradiation, most likely a result of decarboxylation of the nanotube surface. These changes in surface chemistry greatly reduced the colloidal stability of COOH-MWCNTs in NaCl solutions. No noticeable changes in particle surface zeta potential and stability were observed in CaCl2 solutions after irradiation. Consistent with the decreased colloidal stability in NaCl solutions, the irradiated COOH-MWCNTs had a notably higher deposition than the initial COOH-MWCNTs in NaCl solutions when aggregation did not occur. Our results suggest that the photochemical transformation plays an important role in the transport of carbon nanotubes in natural aquatic systems. © 2012 Elsevier Ltd. All rights reserved.

Kim J.,Korea Institute of Toxicology | Kim J.,Korea University | Kang C.-M.,Korea Institute of Toxicology | Kang C.-M.,Chodang University
Bioresource Technology | Year: 2015

The co-digestion of multiple substrates is a promising method to increase methane production during anaerobic digestion. However, limited reliable data are available on the anaerobic co-digestion of food waste leachate with microalgal biomass. This report evaluated methane production by the anaerobic co-digestion of different mixtures of food waste leachate, algal biomass, and raw sludge. Co-digestion of substrate mixture containing equal amounts of three substrates had higher methane production than anaerobic digestion of individual substrates. This was possibly due to a proliferation of methanogens over the entire digestion period induced by multistage digestion of different substrates with different degrees of degradability. Thus, the co-digestion of food waste, microalgal biomass, and raw sludge appears to be a feasible and efficient method for energy conversion from waste resources. © 2015 Elsevier Ltd.

Kim W.-K.,Korea Institute of Toxicology | Lee S.-K.,Korea Institute of Toxicology | Jung J.,Korea University
Journal of Hazardous Materials | Year: 2010

In this study, the toxicological effects of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) toward the common carp, Cyprinus carpio, were evaluated by assessing the responses of five biomarkers, including DNA single-strand breaks (COMET), vitellogenin (VTG) concentration, and the activities of 7-ethoxyresorufin-O-deethylase (EROD), acetylcholinesterase (AChE) and catalase (CAT). Upon PFOA exposure, both the VTG concentration and CAT activity were significantly increased, while there was a negligible change in the responses of other biomarkers when compared to the control. Upon PFOS exposure, a significant increase in the DNA single-strand breaks was observed, while the responses of other biomarkers were not significantly altered when compared to the control. Standardized scores of biomarker responses were visualized using star plots and computed as the integrated biomarker response (IBR). As expected from the different biomarker responses, PFOA and PFOS showed totally different patterns of star plots. Additionally, the IBR values were well correlated with the logarithmic concentrations of PFOA and PFOS (R2=0.9434 and 0.9511, respectively). These results suggest that the IBR might be a useful tool for quantification of various biomarker responses induced by toxic chemicals. © 2010 Elsevier B.V.

Younis H.S.,Isis Pharmaceuticals | Crosby J.,Isis Pharmaceuticals | Huh J.-I.,Korea Institute of Toxicology | Lee H.S.,Korea Institute of Toxicology | And 3 more authors.
Blood | Year: 2012

A strategy to produce sufficient anticoagulant properties with reduced risk of bleeding may be possible through inhibition of factor XI (FXI), a component of the intrinsic coagulation cascade. The objective of this work was to determine the safety profile of ISIS 416858, a 2′-methoxyethoxy (2′-MOE) antisense oligonucleotide inhibitor of FXI, with focus on assessment of bleeding risk. Cynomolgus monkeys administered ISIS 416858 (4, 8, 12, and 40 mg/kg/wk, subcutaneous) for up to 13 weeks produced a dose-dependent reduction in FXI (mRNA in liver and plasma activity) and a concomitant increase in activated partial thromboplastin time (APTT). ISIS 416858 (20 or 40 mg/kg/wk) reduced plasma FXI activity by 80% at 4 weeks of treatment that resulted in a 33% increase in APTT by 13 weeks with no effects on PT, platelets, or increased bleeding following partial tail amputation or gum and skin laceration. The dose-dependent presence of basophilic granules in multiple tissues in ISIS 416858-treated animals was an expected histologic change for a 2′-MOE antisense oligonucleotide, and no toxicity was attributed to hepatic FXI reduction. Basophilic granules reflect cellular drug uptake and subsequent visualization on hematoxylin staining. These results suggest that ISIS 416858 has an acceptable preclinical safety profile and is a promising clinical candidate to treat thrombotic disease. © 2012 by The American Society of Hematology.

Kim J.,Korea Institute of Toxicology | Kim S.,Korea Institute of Toxicology | Lee S.,Korea Institute of Toxicology
Nanotoxicology | Year: 2011

Silver nanoparticles (AgNPs) are increasingly used in various fields. However, little is known about the environmental effects of widespread use of products containing AgNPs. The objective of this study was to determine the ecotoxicity caused by AgNPs. The 48-h effective concentration 50 (EC50) values for Daphnia magna of suspensions of 60 nm and 300 nm AgNPs were 1.0 (95% confidence interval [CI] = 0.1-1.3) and 1.4 (95% CI = 0.3-2.1) μg Ag/l, respectively. The 96 h LC50 values for Oryzias latipes of 60 nm and 300 nm AgNP suspensions were 28 (95% CI = 23-34) and 67 (95% CI = 45-108) μg Ag/l, respectively. To show that toxicity is caused only by Ag+ and not by AgNPs, Ag+ was adsorbed onto the synthesized sorbents packed in a column and D. magna was exposed to the column-passed-300 nm AgNP suspensions. There was no acute toxicity with the AgNP suspensions not containing Ag +. © 2011 Informa UK, Ltd.

Lee Y.-J.,Korea Institute of Toxicology | Kim J.,Korea Institute of Toxicology | Oh J.,Korea Institute of Toxicology | Bae S.,Korea Institute of Toxicology | And 3 more authors.
Environmental Toxicology and Chemistry | Year: 2012

The environmental toxicity associated with silver nanoparticles (AgNPs) has been a major focus in nanotoxicology. The Ag + released from AgNPs may affect ecotoxicity, although whether the major toxic effect is governed by Ag + ions or by AgNPs themselves is unclear. In the present study, we have examined the ecotoxicity of AgNPs in aquatic organisms, silver ion-release kinetics of AgNPs, and their relationship. The 48-h median effective concentration (EC50) values for Daphnia magna of powder-type AgNP suspensions were 0.75μg/L (95% confidence interval [CI]=0.71-0.78) total Ag and 0.37μg/L (95% CI=0.36-0.38) dissolved Ag. For sol-type AgNP suspension, the 48-h EC50 values for D. magna were 7.98μg/L (95% CI=7.04-9.03) total Ag and 0.88μg/L (95% CI=0.80-0.97) dissolved Ag. The EC50 values for the dissolved Ag of powder-type and sol-type AgNPs for D. magna showed similar results (0.37μg/L and 0.88μg/L) despite their differences of EC50 values in total Ag. We observed that the first-order rate constant (k) of Ag + ions released from AgNPs was 0.0734/h at 0.05mg/L total Ag at 22°C within 6h. The kinetic experiments and the toxicity test showed that 36% and 11% of sol-type AgNPs were converted to the Ag + ion form under oxidation conditions, respectively. Powder-type AgNPs showed 49% conversion rate of Ag + ion from AgNPs. We also confirmed that Ag + ion concentration in AgNP suspension reaches an equilibrium concentration after 48h, which is an exposure time of the acute aquatic toxicity test. © 2011 SETAC.

Um M.Y.,Korea Food Research Institute | Hwang K.H.,Korea Institute of Toxicology | Ahn J.,Korea Food Research Institute | Ha T.Y.,Korea Food Research Institute
Basic and Clinical Pharmacology and Toxicology | Year: 2013

Curcumin is a well-known component of traditional turmeric (Curcuma longa), which has been reported to prevent obesity and diabetes. However, the effect of curcumin on hepatic lipid metabolism remains unclear. The aim of this study was to examine the effects of curcumin on hepatic steatosis in high-fat/cholesterol diet (HFD)-induced obese mice. Male C57BL/6J mice were fed a normal diet (ND), HFD or HFD with 0.15% curcumin (HFD+C) for 11 weeks. We found that curcumin significantly lowered the body-weight and adipose tissue weight of mice in the HFD+C group compared with the findings for the HFD group (p < 0.05). The levels of total cholesterol, fasting glucose and insulin in serum were decreased, and HFD-induced impairment of insulin sensitivity was improved by curcumin supplementation (p < 0.05). Curcumin protected against the development of hepatic steatosis by reducing hepatic fat accumulation. Moreover, curcumin activated AMP-activated protein kinase (AMPK) and elevated the gene expression of peroxisome proliferator-activated receptor alpha. By contrast, curcumin suppressed the HFD-mediated increases in sterol regulatory element-binding protein-1, acetyl-CoA carboxylase 1, fatty acid synthase and cluster of differentiation 36 expression. Taken together, these findings indicate that curcumin attenuates HFD-induced hepatic steatosis by regulating hepatic lipid metabolism via AMPK activation, suggesting its use as a therapeutic for hepatic steatosis. © 2013 Nordic Pharmacological Society.

Seo J.-S.,Korea Institute of Toxicology
Journal of the Korean Society for Applied Biological Chemistry | Year: 2012

Mycobacterium aromativorans JS19b1T, isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated site in Hilo, Hawaii, USA, was studied for its degradation of dibenzothiophene (DBT) as a sole carbon source. Strain JS19b1T degraded 100% of DBT (40 mg/L) within 11 days incubation through branched metabolic pathways, including dioxygenation on C-1,2 and C-3,4 positions and monooxygenation on sulfur atom. The metabolites were isolated and identified by gas chromatography-mass spectrometry. Dibenzothiophene-5,5′-dioxide was transformed from sulfur oxidation of DBT. Cis-dibenzothiophene dihydrodiols were detected as initial dioxygenation products. Two ring cleavage products of dibenzothiophene diols were detected as trans-4-(3-hydroxybenzo[b]thiophen-2-yl)-2-oxobut-3-enoic acid and trans-4-(2-hydroxy-benzo[b]thiophen-3-yl)-2-oxobut-3-enoic acid, which could be produced by meta-cleavage of dibenzothiophene-1,2-diol and dibenzothiophene-3,4-diol, respectively. The detection of benzothienopyranone strongly supported that M. aromativorans JS19b1T can degrade DBT through 1,2- and/or 3,4-dioxygenations followed by meta-cleavage. The ring cleavage products were further transformed into 2,2′-dithiosalicylic acid via 2-mercaptobenzoic acid. These results suggested that strain JS19b1T has diverse lateral dioxygenase and metabolic enzyme systems. The diverse DBT metabolic pathways in JS19b1T gave a new insight to the bacterial degradation of aromatic compounds. © 2012 The Korean Society for Applied Biological Chemistry.

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