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Synthesis of S-adenosyl-L-methionine in Escherichia coli
Xiao-Nan Wei,Minjie Cao,Jian Li,Huan Li,Yi Song,Cuihong Du 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.6
S-adenosyl-L-methionine (SAM) is an importantphysiological metabolite in vivo and may be useful inmedicines. SAM is produced from L-methionine and ATPcatalyzed by S-adenosyl-L-methionine synthetase (SAMS)in vivo. In this study, the gene encoding SAMS was clonedand a genetically engineered Escherichia coli (E. coli)BL21(pET-28a-SAMS) was constructed. The recombinantSAMS with a molecular mass of approximately 46 kDawas expressed by inducing the engineered E. coli usingisopropyl-β-D-1-thiogalactopyranoside (IPTG) as an inducer. To produce SAM using a low-cost, nontoxic and highperformanceexpression system, lactose was used as asubstitute for IPTG to induce BL21(pET-28a-SAMS). Byoptimizing the expression conditions, the concentration ofSAM produced by the engineered E. coli was 48 mg/L in theculture medium supernatant. To increase the concentrationof SAM produced, a coupled system was constructedconsisting of E. coli BL21(pET-28a-SAMS) and Saccharomycescerevisiae (S. cerevisiae) JM-310. In this coupled system,ATP generated from S. cerevisiae was provided to E. colifor producing a higher concentration of SAM. The SAMconcentration in the coupled system reached 1.7 g/L. SAMwas purified by a weak acid cationic exchange resin D113,and a simple and economical purification procedure forSAM isolation was achieved. SAM was confirmed byHigh Performance Liquid Chromatography-tandem MassSpectrometry analysis. Our study provides a feasible andconvenient approach to produce SAM.
Pu-erh Tea Powder Preventive Effects on Cisplatin-Induced Liver Oxidative Damage in Wistar Rats
Zheng, Xiao-Nan,Wang, Xiao-Wen,Li, Li-Ya,Xu, Zi-Wei,Huang, Hsin-Yi,Zhao, Jin-Sheng,Zhang, Duo,Yin, Xu,Sheng, Jun,Tang, Jin-Tian Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17
Background: Chemotherapy is one of the major means for control of malignancies, with cisplatin (CDDP) as one of the main agents, widely used for the treatment of various malignant solid tumors. However, prevention of hepatotoxicity from cisplatin is one of the urgent issues in cancer chemotherapy. In this study, we aimed to investigate the effects of pu-erh tea on hepatotoxicity through body weight and tissue antioxidant parameters like, liver coefficient, serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), malondialdehyde(MDA) and glutathione (GSH) levels, and light microscopic evaluation by histological findings. Materials and Methods: The rats were randomly divided into five groups: Control (n=10), cisplatin (3 mg/kg p.i., n=10), cisplatin+pu-erh (0.32 g/kg/day i.g., n=10), cisplatin+pu-erh (0.8 g/kg/day i.g., n=10) and cisplatin+pu-erh (1.6 g/kg/day i.g., n=10). Pu-erh tea powder was administrated for 31 consecutive days. The rats were sacrificed at the end on the second day after a single dose of cisplatin treatment for measuring indices. Results: Pu-erh tea powder exhibited a protective effect by decreasing MDA and GSH and increasing the SOD and GSH-PX levels and GSH-PX/MDA ratio in camparison with the control group. Besides, pu-erh tea was also able to alleviate the pathological damage to some extent. Conclusion: Pu-erh tea powder is protective against cisplatin-induced liver oxidative damages, especially at the medium dosage (0.8 g/kg/d).
Optical Properties of K9 Glass Waveguides Fabricated by Using Carbon-Ion Implantation
Chun-Xiao Liu,Wei Wei,Li-Li Fu,Xu-Feng Zhu,Hai-Tao Guo,Wei-Nan Li,She-Bao Lin 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.2
K9 glass is a material with promising properties that make it attractive for optical devices. Ion implantation is a powerful technique to form waveguides with controllable depth and refractive index profile. In this work, optical planar waveguide structures were fabricated in K9 glasses by using 6.0-MeV C3+-ion implantation with a fluence of 1.0 × 1015 ions/cm2. The effective refractive indices of the guided modes were measured by using a prism-coupling system. The refractive index change in the ion-irradiated region was simulated by using the intensity calculation method. The modal intensity profile of the waveguide was calculated and measured by using the finite difference beam propagation method and the end-face coupling technique, respectively. The transmission spectra before and after the implantation showed that the main absorption band was not influenced by the low fluence dopants. The optical properties of the carbon-implanted K9 glass waveguides show promise for use as integrated photonic devices.
( Wen Qian Wei ),( Fang Qi Liu ),( Lei Liu ),( Zuo Feng Li ),( Xiao Yan Zhang ),( Fan Jiang ),( Qu Shi ),( Xiao Yan Zhou ),( Wei Qi Sheng ),( San Jun Cai ),( Xuan Li ),( Ye Xu ),( Peng Nan ) 생화학분자생물학회(구 한국생화학분자생물학회) 2011 BMB Reports Vol.44 No.5
Hereditary non-polyposis Colorectal Cancer (HNPCC) is an autosomal dominant inheritance syndrome. HNPCC is the most common hereditary variant of colorectal cancer (CRC), which accounts for 2-5% CRCs, mainly due to hMLH1 and hMSH2 mutations that impair DNA repair functions. Our study aimed to identify the patterns of hMSH2 and hMLH1 mutations in Chinese HNPCC patients. Ninety-eight unrelated families from China meeting Amsterdam or Bethesda criteria were included in our study. Germline mutations in MLH1 and MSH2 genes, located in the exons and the splice-site junctions, were screened in the 98 probands by direct sequencing. Eleven mutations were found in ten patients (11%), with six in MLH1 (54.5%) and five in MSH2 (45.5%) genes. One patient had mutations in both MLH1 and MSH2 genes. Three novel mutations in MLH1 gene (c.157_160delGAGG, c.2157dupT and c.-64G>T) were found for the first time, and one suspected hotspot in MSH2 (c.1168C>T) was revealed. [BMB reports 2011; 44(5): 317-322]
Bandwidth-Related Optimization in High-Speed Frequency Dividers using SiGe Technology
Nan, Chao-Zhou,Yu, Xiao-Peng,Lim, Wei-Meng,Hu, Bo-Yu,Lu, Zheng-Hao,Liu, Yang,Yeo, Kiat-Seng The Institute of Electronics and Information Engin 2012 Journal of semiconductor technology and science Vol.12 No.1
In this paper, the trade-off related to bandwidth of high-speed common-mode logic frequency divider is analyzed in detail. A method to optimize the operating frequency, band-width as well as power consumption is proposed. This method is based on bipolar device characteristics, whereby a negative resistance model can be used to estimate the optimal normalized upper frequency and lower frequency of frequency dividers under different conditions, which is conventionally ignored in literatures. This method provides a simple but efficient procedure in designing high performance frequency dividers for different applications. To verify the proposed method, a static divide-by-2 at millimeter wave ranges is implemented in 180 nm SiGe technology. Measurement results of the divider demonstrate significant improvement in the figure of merit as compared with literatures.
Xiao-Wei Tang,Ji-Lei Hu,Jiang-Nan Qiu 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.7
Soil liquefaction causes extensive damages to buildings and infrastructures during earthquakes. It is very important to identify the significant parameters controlling seismic liquefaction which will enhance the predictability of evaluation models. In order to identify the significant factors, 203 literatures about soil liquefaction are analyzed by bibliometrics, 12 significant factors, such as: magnitude, epicentral distance, duration of earthquake, fines content, particle size, grain composition, relative density, drainage condition, degree of consolidation, thickness of sand layer, depth of sand layer, groundwater table, are identified among 22 influence factors. And then the interrelationship among the 12 main factors was analyzed, and a multilevel structure hierarchy is developed by interpretive structural modeling, which would help understand more clearly about the relationships among these factors. The results show that: magnitude, epicentral distance, duration of earthquake and drainage condition have a direct impact on soil liquefaction, and fines content plays a key role in all factors. The results can provide guidelines for election of factors and the establishment of model in the risk evaluation of soil liquefaction.
Modulation of the Self-Assembly of Collagen by Phytic Acid: An In Vitro Study
Xiao Tu,Xincheng Chen,Ying Peng,Jie Nan,Benmei Wei,Lang He,Chengzhi Xu,Yuling Xu,Dong Xie,Juntao Zhang,Haibo Wang 한국고분자학회 2018 Macromolecular Research Vol.26 No.13
Phytic acid, containing a myoinositol ring coupled with six phosphate groups, can react with the amino groups of collagen to regulate their self-assembly behavior. The aim of this research is to evaluate the effects of phytic acid on the selfassembly behavior of collagen, the structures and properties of the resulting fibrils and hydrogels. Turbidity and chloramine T assay suggested that phytic acid could improve the self-assembly kinetics and degree of collagen, and the optimal ratio of phytic acid/collagen was 1/1 (w/w). Scanning electron microscopy (SEM) analysis indicated that co-fibrils of collagen with phytic acid are more slender than that of pure collagen, and transmission electron microscopy (TEM) reveals that the characteristic D-periodicity of collagen fibrils is not affected by phytic acid. Besides, differential scanning calorimetry (DSC) and rheology revealed that the thermal stability of collagen fibrils and the viscoelasticity of collagen hydrogels could be improved by phytic acid and the optimal ratio of phytic acid/collagen is 1/1 (w/w).
Mean Square Detectability of LTI Systems over Finite-State Digital Block-Fading Channels
Wei Chen,Yuanyuan Zou,Nan Xiao,Yugang Niu 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.2
This paper studies the mean square quadratic (MSQ) detectability for multi-output networked systemsover finite-state digital block-fading channels. The packet-loss rate of each digital fading channel depends on thechannel power gain, as well as packet length and power level used for transmission. A finite-state random processis introduced to model time-varying fading channels, which characterizes various configurations of physical communicationenvironment and/or different channel fading amplitudes. Necessary and sufficient conditions for MSQdetectability over finite-state Markov digital block-fading channels are given in the form of algebraic Riccati equationsor linear matrix inequalities (LMIs). The estimation gain is given as a function of estimated/observed channelstate. In addition, explicit conditions on network for MSQ detectability over finite-state independent identicallydistributed (i.i.d.) digital block-fading channels are presented in terms of the unstable poles of the multi-outputplant. Finally, an application to Gilbert-Elliott channels (GECs) is provided to demonstrate the derived results.