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Guangzhi Li,Junchi Wang,Xiaojin Li,Jianguo Xu,Zhao Zhang,Jianyong Si 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.6
20-Z auraptene (1) is a synthesized monoterpenecoumarin with anticancer activity against human gastriccancer cells. In order to find new potential anticancer agent,Mucor polymorphosporus was used to transform cis-auraptene. Four new terpene coumarins with notable changesin the skeletal backbone, 20-Z auraptene A-D (2–5), wereobtained and evaluated for their antiproliferative effectsagainst human normal gastric epithelium cells and humangastric cancer cells. These new compounds showed selectivecytotoxic activity against MGC-803 cells with IC50values from 0.78 ± 0.13 to 10.78 ± 1.83 lM and thetherapeutic index could also be significantly improved(TI = 59.0) compared with that of 1 (TI = 5.5). Thestructures of these metabolites were elucidated throughextensive spectroscopic methods, and the possible biotransformationpathway of 1 by Mucor polymorphosporuswas also proposed. Furthermore, the mechanism of theantiproliferative effects against MGC-803 cells of the mostpotent compound, 20-Z auraptene A (2), was characterized. Annexin V/PI staining and abnormal expression of apoptosis-related protein suggested that compound 2 inducesapoptosis in gastric cancer MGC-803 cells. Therefore, it ispossible that compound 2 has the potential to be applied ingastric cancer therapy.
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DRA0336, Another OxyR Homolog, Involved in the Antioxidation Mechanisms in Deinococcus radiodurans
Longfei Yin,Liangyan Wang,Huiming Lu,Guangzhi Xu,Hongdan Zhan,Bing Tian,Yuejin Hua,Huan Chen 한국미생물학회 2010 The journal of microbiology Vol.48 No.4
A novel OxyR (DR0615) with one conserved cysteine that senses hydrogen peroxide in Deinococcus radiodurans had been identified in our previous work. Comparative genomics revealed that D. radiodurans possesses another OxyR homolog, OxyR2 (DRA0336). In this study, we constructed the deletion mutant of oxyR2 and the double mutant of both the OxyR homologs to investigate the role of OxyR in response to oxidative stress in D. radiodurans. Deletion of oxyR2 resulted in an obviously increased sensitivity to hydrogen peroxide, and the double mutant for oxyR and oxyR2 was significantly more sensitive than any of the two single mutants. The total catalase activity of the double mutant was lower than that of any of the single mutants, and reactive oxygen species (ROS) accumulated to a greater extent. DNA microarray analysis further suggested that oxyR2 was involved in antioxidation mechanisms. Site-direct mutagenesis and complementation analysis revealed that C228 in OxyR2 was essential. This is the first report of the presence of two OxyR in one organism. These results suggest that D. radiodurans OxyR and OxyR2 function together to protect the cell against oxidative stress.
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Adaptive Sliding Mode Control of a Transport Aircraft for Heavyweight Airdrop
Ri Liu,Xiuxia Sun,Wenhan Dong,Guangzhi Xu 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
This paper investigates the problem of designing a novel sliding mode controller of a transport aircraft for airdrop modes in the presence of bounded nonlinear uncertainty and actuator fault without the prior knowledge of the bounds. On the basis of feedback linearization of the aircraft-cargo dynamic model, an autopilot inner-loop which combines sliding mode control with adaptive function approximation is developed. The complex nonlinear uncertainty of the model is factorized into a known matrix and an uncertainty function. An adaptive approximation approach is used to estimate the function, and it overcomes the conservation drawback of the sliding mode control that relies on the bounds on the uncertainty/actuator fault. Notably, the adaptation law formed using the projection operator can bound the estimated function, and this avoids singularity of the control signal. Simulations verify the good performance of the control system, which can satisfy the airdrop mission performance indexes well, even in the presence of ±20% aerodynamic coefficients uncertainty and 20% actuator fault.
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