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Roh, Taehyun,De, Umasankar,Lim, Seong Kwang,Kim, Min Kook,Choi, Seul Min,Lim, Duck Soo,Yoon, Sungpil,Kacew, Sam,Kim, Hyung Sik,Lee, Byung-Mu Elsevier 2018 Food and chemical toxicology Vol.114 No.-
<P><B>Abstract</B></P> <P>The detoxifying effect of pyridoxine against acetaminophen (APAP)-induced hepatotoxicity was investigated. HepG2 cells were co-treated with APAP and pyridoxine to compare with betaine or methionine for 24 h. LDH, ALT and AST activities were measured to determine direct cells damage <I>in vitro</I> and in vivo. Lipid peroxidation, antioxidant enzymes activity, and glutathione level were measured. Cytochrome c releaseand procaspase-3, cleaved caspase-3, Bcl-2, or Bax protein levels were measured to determine APAP-induced apoptotic cell death. Pyridoxine treatment significantly increased cell viability and decreased leakage of LDH activity against APAP-induced hepatotoxicity in HepG2 cells. ALT and AST activities were dose-dependently reduced by pyridoxine treatment compared to APAP-treated group. Significant increases in activities of GST and GPx were observed after co-treatment with APAP and pyridoxine. Although APAP-induced Nrf2 and HO-1 expression levels were gradually reduced in HepG2 cells by pyridoxine treatment, induction of antioxidant enzymes activities were dose-dependently increased. These protected effects of pyridoxine against APAP-induced hepatoxicity were closely associated with suppression of APAP-induced oxidative stress and apoptotic cell death in HepG2 cells. These data indicated that the protective action of pyridoxine against hepatic cell injuries was involved in the direct antioxidant activity which provides a pivotal mechanism for its potential hepatoprotective action.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pyridoxine decreased LDH, ALT and AST activities against APAP-induced hepatotoxicity <I>in vitro</I> and in vivo. </LI> <LI> Increases in antioxidant enzymes (GST and GPx) and GSH levels were observed after co-treatment with APAP and pyridoxine. </LI> <LI> Cytochrome c and procaspase-3, Bcl-2, or Bax protein levels were measured to determine APAP-induced apoptotic cell death. </LI> <LI> The protective action of pyridoxine against hepatic cell injuries was involved in the direct antioxidant activity. </LI> <LI> Pyridoxine showed protective activity via HO-1 induction serving as a key player in APAP-induced cell survival pathway. </LI> </UL> </P>
The East-Asian VLBI Network: Recent Progress and Results of the First Imaging Test Observation
Kiyoaki Wajima,Duk-Gyoo Roh,Se-Jin Oh,Taehyun Jung,Jongsoo Kim,Yoshiaki Hagiwara,Kazuhiro Hada,Noriyuki Kawaguchi,Hideyuki Kobayashi,Yuanwei Wu,Kenta Fujisawa,Tao An,Willem A. Baan,Wu Jiang,Zhi-Qiang 한국천문학회 2016 天文學會報 Vol.41 No.1
EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: EVALUATION OF SYSTEM PERFORMANCE
Lee, Sang-Sung,Petrov, Leonid,Byun, Do-Young,Kim, Jongsoo,Jung, Taehyun,Song, Min-Gyu,Oh, Chung Sik,Roh, Duk-Gyoo,Je, Do-Heung,Wi, Seog-Oh,Sohn, Bong Won,Oh, Se-Jin,Kim, Kee-Tae,Yeom, Jae-Hwan,Chung, American Institute of Physics 2014 The Astronomical journal Vol.147 No.4
<P>We report the very long baseline interferometry (VLBI) observing performance of the Korean VLBI Network (KVN). The KVN is the first millimeter-dedicated VLBI network in East Asia. The KVN consists of three 21 m radio telescopes with baseline lengths in a range of 305-476 km. The quasi-optical system equipped on the antennas allows simultaneous observations at 22, 43, 86, and 129 GHz. The first fringes of the KVN were obtained at 22 GHz on 2010 June 8. Test observations at 22 and 43 GHz on 2010 September 30 and 2011 April 4 confirmed that the full cycle of VLBI observations works according to specification: scheduling, antenna control system, data recording, correlation, post-correlation data processing, astrometry, geodesy, and imaging analysis. We found that decorrelation due to instability in the hardware at times up to 600 s is negligible. The atmosphere fluctuations at KVN baseline are partly coherent, which allows us to extend integration time under good winter weather conditions up to 600 s without significant loss of coherence. The post-fit residuals at KVN baselines do not exhibit systematic patterns, and the weighted rms of the residuals is 14.8 ps. The KVN is ready to image compact radio sources both in snapshot and full-track modes with residual noise in calibrated phases of less than 2 deg at 22 and 43 GHz and with dynamic ranges of ~300 for snapshot mode and ~1000 for full-track mode. With simultaneous multi-frequency observations, the KVN can be used to make parsec-scale spectral index maps of compact radio sources.</P>
Choi, Lan,Kwak, Min Young,Kwak, Eun Hwa,Kim, Dong Hyun,Han, Eun Young,Roh, Taehyun,Bae, Jung Yun,Ahn, Il Young,Jung, Jea Yeon,Kwon, Mi Jung,Jang, Dong Eun,Lim, Seong Kwang,Kwack, Seung Jun,Han, Soon Y Taylor Francis 2010 Journal of toxicology and environmental health. Pa Vol.73 No.21
<P>Acute nephrotoxicities of melamine (MEL), cyanuric acid (CA), and a mixture of both melamine and cyanuric acid (MC) were comparatively investigated in male Sprague-Dawley rats at 5 doses each with 10-fold dose interval as follows: MEL at 0.0315, 0.315, 3.15, 31.5, and 315 mg/kg; CA at 0.025, 0.25, 2.5, 25, and 250 mg/kg, and MC: [1×: (0.0315 + 0.025), 10×: (0.315 + 0.25), 100×: (3.15 + 2.5), 1000×: (31.5 + 25), and (315 + 250) mg/kg]. No marked adverse effects in renal function were observed in animals treated with MEL alone or CA alone, but evidence related to nephrotoxicity was noted in rats administered MC. Renal calculi and increased kidney weights were found in rats 7 d after daily oral administration of MC. Blood urea nitrogen (BUN) and creatinine were significantly elevated in the high dose MC groups at 100× or 1000×. In addition, elevated numbers of white blood cells (WBC), neutrophils, and lymphocytes in vivo and increased levels of prostaglandin E(2) (PGE(2)) in vitro were found in the MC group. Based on these data, the NOAEL (no-observed-adverse-effect level) for nephrotoxicity for MC was estimated to be 3.15 mg/kg body weight (bw)/d (MEL) plus 2.5 mg/kg bw/d (CA). If a safety factor of 1000 or more were applied to NOAEL, tolerable daily intake (TDI) would be 0.00315 and 0.0025 mg/kg/d or less for MEL and CA, respectively, which is far below the TDI of 0.2 mg/kg/d set by World Health Organization (WHO). In addition, in vitro cytotoxicity assays showed that the ACHN human renal adenocarcinoma cell line was more sensitive to MEL, CA, and MC than the MDCK canine kidney epithelial cell line. The 24-h half maximal inhibitory concentration (IC(50)) values for MEL (4792, 2792 관g/ml) were less than those of CA (9890, 6725 관g/ml, respectively) in MDCK and ACHN cell lines, suggesting that MEL may be more cytotoxic than CA. Furthermore, the 24-h IC(50) value for MC was found to be 208 관g/ml in ACHN cells. Data suggest that NOAELs based upon acute nephrotoxic parameters for MC were low, which might require further reassessment of the current TDI.</P>