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Hwang, Tae-Yeon,Go, Gwang-Myeong,Park, Siwoo,Lee, Jimin,Song, Yoseb,Kim, Seil,Cho, Hong-Baek,Choa, Yong-Ho American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.50
<P>We present a thermochemical hydrogen (TCH) gas sensor fabricated with Pt-decorated exfoliated graphene sheets and a tellurium nanowire-based thermoelectric (TNTE) layer operating at room temperature in wet air. The sensor device was able to detect 50 ppm to 3% of hydrogen gas within several seconds (response/recovery times of 6/5.1 s at 4000 ppm of hydrogen gas) at room temperature due to the relatively high surface area of homogeneously dispersed Pt nanocrystals (∼8 nm) decorated on graphene sheets and the excellent Seebeck coefficient (428 μV/K) of the TNTE layer. Furthermore, it was observed that the effect of the relative humidity on sensing properties was greatly minimized by incorporating Pt-decorated graphene sheets. These results indicate that our device has great potential as a low power consumption gas sensor for IoTs.</P> [FIG OMISSION]</BR>
( Yong Pil Hwang ),( Hyun Gyun Kim ),( Jae Ho Choi ),( Minh Truong Do ),( Young Chul Chung ),( Tae Cheon Jeong ),( Hye Gwang Jeong ) 영남대학교 약품개발연구소 2013 영남대학교 약품개발연구소 연구업적집 Vol.23 No.0
S-Allyl cysteine (SAC), a nontoxic garlic compound, has a variety of pharmacological properties, including antioxidant and hepatoprotective properties. In this report, we provide evidence that SAC prevented free fatty acid (FFA)-induced lipid accumulation and lipotoxicity in hepatocytes. SAC significantly reduced FFA-induced generation of reactive oxygen species, caspase activation and subsequent cell death. Also, SAC mitigated total cellular lipid and triglyceride accumulation in steatotic HepG2 cells. SAC significantly increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells. Additionally, SAC down-regulated the levels of sterol regulatory element binding protein-1 (SREBP-1) and its target genes, including ACC and fatty acid synthase. Use of a specific inhibitor showed that SAC activated AMPK via calcium/calmodulin-dependent kinase kinase (CaMKK) and silent information regulator T1. Our results demonstrate that SAC activates AMPK through CaMKK and inhibits SREBP-1-mediated hepatic lipogenesis. Therefore, SAC has therapeutic potential for preventing nonalcoholic fatty liver disease. ⓒ2013 Elsevier lnc. Arl rights resetved.
Cephalosporin C 생물전환 반응의 Computer Simulation
황광모,강용호 영남대학교 자원문제연구소 2000 資源問題硏究 Vol.19 No.-
In CPC bioconversion process with D-amino acid oxidase(D-AAO), sufficient oxygen supply is critical to get the maximum yield of glutaryl-7ACA D-AAO immobilized in a solid matrix usually have lack of oxygen molecules due 0 the mass-transfer resistance of the matrix. To understand the effect of o10rgen mass-transfer coefficient, KLa on production of glutaryl-7ACA quantitatively, simulation of cephalosporin C bioconversion process was performed by numerical analysis of six ordinary differential equations.
Hwang, Yong Pil,Yun, Hyo Jeong,Choi, Jae Ho,Kang, Keon Wook,Jeong, Hye Gwang WILEY-VCH Verlag 2010 Molecular nutrition & food research Vol.54 No.7
<P>Matrix metalloproteinase (MMP) plays an important role in the invasion and metastasis of cancer cells. The inhibitory effects of bergamottin, a cytochrome P450 inhibitor from Citrus paradis (grapefruit), on tumor invasion and migration and the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma HT-1080 cells. Bergamottin reduced phorbol-12-myristate-13-acetate (PMA)-induced activation of MMP-9 and MMP-2 and further inhibited cell invasion and migration. Bergamottin suppressed PMA-enhanced expression of MMP-9 protein, mRNA and transcription activity levels through suppression of nuclear factor-κB (NF-κB) activation without changing the tissue inhibitor of metalloproteinase 1 level. Bergamottin also reduced PMA-enhanced MMP-2 expression through suppression of membrane-type 1 MMP, but did not alter tissue inhibitor of metalloproteinase 2 levels. Bergamottin inhibited PMA-induced NF-κB nuclear translocation and IκBα degradation, which are upstream of PMA-induced MMP-9 expression and invasion. Furthermore, bergamottin strongly repressed the PMA-induced phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK), which are dependent on the protein kinase C-δ pathway. In conclusion, we demonstrated that the anti-invasive effects of bergamottin might occur through inhibition of protein kinase C-δ, p38 mitogen-activated protein kinase, and JNK phosphorylation and reduction of NF-κB activation, leading to downregulation of MMP-9 expression. These results suggest that the suppression of MMP expression contributes, at least in part, to the antitumor activity of bergamottin.</P>
Protective Effects of Puerarin on Carbon Tetrachloride-Induced Hepatotoxicity
Hwang, Yong-Pil,Choi, Chul-Yung,Chung, Young-Chul,Jeon, Seong-Sik,Jeong, Hye-Gwang 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.10
Puerarin, the main isoflavone glycoside found in the root of Pueraria lobata, has been used for various medicinal purposes in traditional Chinese medicine for thousands of years. The purpose of this study was to investigate the protective effects of puerarin against hepatotqxicity induced by carbon tetrachloride ($CCI_4$) and the mechanism of its hepatoprotective effect. In mice, pretreatment with puerarin prior to the administration of $CCI_4$ significantly prevented the increased serum enzymatic activity of alanine aspartate aminotransferase and hepatic malondialdehyde formation in a dose-dependent manner. In addition, pretreatment with puerarin significantly prevented both the depletion of reduced glutathione (GSH) content and the decrease in glutathione S-transferase (GST) activity in the liver of $CCI_4$-intoxicated mice. Hepatic GSH levels and GST activity were increased by treatment with puerarin alone. $CCI_4$-induced hepatotoxicity was also prevented, as indicated by liver histopathology. The effects of puerarin on cytochrome P450 (CYP) 2E1, the major isozyme involved in $CCI_4$ bioactivation, were also investigated. Treatment of the mice with puerarin resulted in a significant decrease in the CYP2E1-dependent aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the CYP2E1 protein levels were also lowered. Puerarin exhibited anti-oxidant effects on $FeCl_2$-ascorbate induced lipid peroxidation in mouse liver homogenates, and on superoxide radical scavenging activity. These results suggest that the protective effects of puerarin against the $CCI_4$-induced hepatotoxicity possibly involve mechanisms related to its ability to block CYP-mediated $CCI_4$ bioactivation, induction of GST activity and free radical scavenging effects.