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Articles by Wei Zhang
Total Records ( 20 ) for Wei Zhang
  Huaiyu Wang , Junhui Ji , Wei Zhang , Yihe Zhang , Jiang Jiang , Zhengwei Wu , Shihao Pu and Paul K. Chu
  Poly(butylene succinate) (PBSu), a novel biodegradable aliphatic polyester with excellent processability and mechanical properties, is a promising substance for bone and cartilage repair. However, it typically suffers from insufficient biocompatibility and bioactivity after implantation into the human body. In this work, H2O or NH3 plasma immersion ion implantation (PIII) is conducted for the first time to modify the PBSu surface. Both the treated and control specimens are characterized by X-ray photoelectron spectroscopy, contact angle measurements and atomic force microscopy. The plasma treatments improve the hydrophilicity and roughness of PBSu significantly and the different PIII processes result in similar hydrophilicity and topography. C–OH and C–NH2 functional groups emerge on the PBSu surface after H2O and NH3 PIII, respectively. The biological results demonstrate that both osteoblast compatibility and apatite formability are enhanced after H2O and NH3 PIII. Furthermore, our results suggest that H2O PIII is more effective in rendering PBSu suitable for bone-replacement implants compared to NH3 PIII.
  Ling Zhao , Kaiyu Wang , Dexiang Wang , Chang Liu and Wei Zhang
  Microwave-assisted extraction was investigated for extraction of polysaccharides from Catathelasma ventricosum using Response Surface Methodology (RSM). The effects of operating conditions (extraction time, microwave power and ratio of water to raw material) on the extraction yield of polysaccharides were studied. A Box-Behnken Design was used for experimental design and analysis of the results to obtain the optimal processing parameters. Among the three extraction parameters, the microwave power was the most significant factor to affect the yield of polysaccharides from Catathelasma ventricosum. In addition, microwave power and extraction time had significant interaction effects. A mathematical model with high determination coefficient was gained and could be employed to optimize polysaccharides extraction and the optimal conditions were extraction time 5 min, microwave power 420 W, ratio of water to raw material 25:1. Under these conditions, the experimental yield of polysaccharide was 7.83±0.19% which was close to the predicted value.
  Jing-Cao Pan , Rong Ye , Hao-Qiu Wang , Hai-Qing Xiang , Wei Zhang , Xin-Fen Yu , Dong-Mei Meng and Zhe-Sheng He
  A conjugative plasmid, pMRV150, which mediated multiple-drug resistance (MDR) to at least six antibiotics, including ampicillin, streptomycin, gentamicin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole, was identified in a Vibrio cholerae O139 isolate from Hangzhou, eastern China, in 2004. According to partial pMRV150 DNA sequences covering 15 backbone regions, the plasmid is most similar to pIP1202, an IncA/C plasmid in an MDR Yersinia pestis isolate from a Madagascar bubonic plague patient, at an identity of 99.99% (22,180/22,183 nucleotides). pMRV150-like plasmids were found in only 7.69% (1/13) of the O139 isolates tested during the early period of the O139 epidemic in Hangzhou (1994, 1996, and 1997); then the frequency increased gradually from 60.00% (3/5) during 1998 and 1999 to 92.16% (47/51) during 2000 to 2006. Most (42/51) of the O139 isolates bearing pMRV150-like plasmids were resistant to five to six antibiotics, whereas the plasmid-negative isolates were resistant only to one to three antibiotics. In 12 plasmid-bearing O139 isolates tested, the pMRV150-like plasmids ranged from approximately 140 kb to 170 kb and remained at approximately 1 or 2 copies per cell. High (4.50 x 10–2 and 3.08 x 10–2) and low (0.88 x 10–8 to 3.29 x 10–5) plasmid transfer frequencies, as well as no plasmid transfer (under the detection limit), from these O139 isolates to the Escherichia coli recipient were observed. The emergence of pMRV150-like or pIP1202-like plasmids in many bacterial pathogens and nonpathogens occupying diverse niches with global geographical distribution indicates an increasing risk to public health worldwide. Careful tracking of these plasmids in the microbial ecosystem is warranted.
  Wei Zhang , Junjian Huang and Pengcheng Wei
  This paper deals with the synchronization of two coupled identical chaotic systems with parameter mismatch via using periodically intermittent control. In general, parameter mismatches are considered to have a detrimental effect on the synchronization quality between coupled identical systems: in the case of small parameter mismatches the synchronization error does not decay to zero or even a nonzero mean. Larger values of parameter mismatches can even result in the loss of synchronization. via intermittent control with periodically intervals, we can obtain the weak synchronization. Some sufficient conditions for the stabilization and weak synchronization of a large class of coupled identical chaotic systems will be derived by using Lyapunov stability theory. The analytical results are confirmed by numerical simulations.
  Yilma Taye Desta , Jiang Tao and Wei Zhang
  This study reports a detailed review on selected channel estimation algorithms for orthogonal frequency division multiplexing communication systems. Pilot based channel estimation algorithms such as least square, minimum mean square error, maximum likelihood and decision feedback estimators are discussed and also compared in terms of their simplicity, computational cost and suitability conditions. Moreover Subspace Based Blind channel estimation algorithm for cyclic prefix system is described along with its limitation of applicability for fast varying wireless channels. References for the report and other estimating algorithms which are not considered here are also cited.
  Wei Zhang , Jianzhong Li , Shengfei Shi and Haiwei Pan
  The predictive Spatio-temporal range query returns a set of moving objects that will appear in a spatial query range during a future temporal query interval. A novel approach is proposed to continuously monitor the changes in the results of predictive queries as objects moves. Two index structures are designed to increase the efficiency of query monitoring. The experimental evaluation shows that the proposed method can efficiently monitor massive predictive Spatio-temporal range queries over moving objects.
  Xin Jin , Yifei Chen , Nong Yu , Xianghua Zuo , Shiping Song , Xiuyun Yin , Yuan Huang , Wei Zhang and Jiankui Chen
  Invasive Aspergillosis (IA) is one of the most common life-threatening opportunistic invasive mycosis in hematological cancer patients. Early diagnosis of IA is difficult; the need for early clinical diagnosis and management presents the need for new noninvasive, culture-independent diagnostic tools. Galactomannan (GM) and (1-3)-β-D-glucan (BG) antigenemia can serve as useful markers for IA. The current study was conducted to prospectively evaluate the clinical significance of GM and BG detection in the diagnosis of IA in patients with hematological malignancies in China. In 378 patients with hematological malignancies, GM and BG were detected. Analysis of sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of GM and BG assay were performed. Detection of BG for diagnosis of IA with plasma reported sensitivity, specificity, PPV and NPV values as 66, 92, 86 and 78%, respectively. The GM detection for diagnosis of IA in serum reported sensitivity, specificity, PPV and NPV values as 48, 97, 93 and 71%, respectively. Combination of the two tests improved the specificity (to 100%) and PPV value (to 100%) of each individual test without affecting the sensitivity and NPV. The study concluded that serum GM and plasma BG can serve as potential markers of Aspergillosis. The detection of GM and BG has shown high specificity and PPV for screening high-risk hematological patients. The combined measurement of GM and BG appeared to be useful for early diagnosis of IA.
  Chunwang Yue , Maohong Sun , Haiying Liu , Wei Zhang , Xiaoping Zhu , Xianghao Kong and Zhihai Jia
  The aim of this research was to investigate the changes of the Monodeiodinase (MD) gene mRNA in skin of cashmere goats from the initiation of cashmere fibre growth to normal growth. The Melatonin (MT) implants were used in order to initiate growth of cashmere fibre before normal time. Real-time reverse transcription quantitative Polymerase Chain Reaction (real-time PCR) was used to determine the MD gene mRNA expression levels of skin. The results show that the MT concentration was significant differences after administration from July to November the cashmere fibre growth rate was markedly greater in group of MT implant (M group) than that of the group of control (C group) in July (p<0.01), August (p<0.001) and September (p<0.05), the expression of cashmere goat skin MDII mRNA is gradually increased from June to September and then decreased gradually after the implant MT MDII mRNA expression increased rapidly, M and C group in July was significantly different (p<0.01) and August are still significant differences (p<0.05), the M and C group MDIII mRNA expression showed a downward trend from June to November in Cashmere goat skin and the M and C group did not appear significant differences (p>0.05) in the monthly. These results suggest that the expression levels of MDII mRNA may be involved in the process of cashmere growth, it expression may have a specific signaling pathway in cashmere goats skin, especially in the initiation of cashmere fibre growth period.
  Ming Guo , Yun Gong , Michael Deavers , Elvio G. Silva , Yee Jee Jan , David E. Cogdell , Rajyalashmi Luthra , E. Lin , Hung Cheng Lai , Wei Zhang and Nour Sneige
  To evaluate a commercialized in situ hybridization (ISH) assay for detecting human papillomavirus (HPV) DNA, we compared the ability of a new ISH probe, Inform HPV III (Ventana Medical Systems, Tucson, AZ), to that of PCR assays to detect HPV DNA in cervical tissue specimens with normal cervix (20 cases), cervical intraepithelial neoplasia (CIN; CIN 1, 27 cases; CIN 2, 28 cases; and CIN 3, 33 cases), and cervical carcinoma (29 cases). General HPV DNA was detected using consensus primer-mediated PCR assays. HPV genotyping was performed by using EasyChip HPV blot (King Car Yuan Shan Institute, I-Lan, Taiwan). HPV16 integration status (E2/E6 ratio) was determined by using quantitative real-time PCR. Our findings showed that the ISH and PCR had fair to good agreements in detecting HPV DNA across all CIN categories without significant differences (Kappa coefficient, 0.34 to 0.63; P = 0.13 to 1.0). However, ISH detected significantly fewer HPV-positive cases in carcinoma than PCR did (Kappa coefficient, 0.2; P = 0.03). Eleven cases with ISH– PCR+ results had HPV types that can be detected by Inform HPV III. Five carcinoma cases with ISH– PCR+ results showed a significantly higher level of integrated HPV16 (P = 0.008) than did the ISH+ cases. As a consequence, lower copy numbers of episomal HPV16 in carcinoma might be the cause for the false-negative ISH results. Although the punctate signal pattern of HPV significantly increased with the severity of disease (P trend = 0.01), no significant difference in the HPV16 integration status was observed between the cases with a punctate signal only and the cases with mixed punctate and diffuse signals (P = 0.4). In conclusion, ISH using the Inform HPV III probe seems comparable to PCR for detecting HPV DNA in cervical tissue with CINs. False-negative ISH results appear to be associated with the lower copy numbers of the episomal HPV16 but not with the ability of the Inform HPV III probe to detect specific HPV types. In addition, signal patterns, especially a mixed punctate and diffuse pattern of HPV, cannot be reliably used to predict viral integration status.
  Dan Feng , Shu-Xia Liu , Ping Sun , Feng-Ji Ma and Wei Zhang
  A 2-D coordination polymer with mixed ligands, [Zn2(BDC)(4,4'-bipy) (HCOO)2] (1) (BDC, 1,4-benzenedicarboxylate; 4,4'-bipy, 4,4'-bipyridine), has been synthesized by solvothermal reaction. Compound 1 provides the first coordination polymer structure constructed by bridging BDC, 4,4'-bipy, and formate. Both BDC and 4,4'-bipy link zincs alternatively, resulting in a zigzag coordination chain; adjacent chains are further linked by formates to form an infinite extended 2-D folding screen layer. The synthesis mechanism and fluorescence property are discussed.
  Xiao-Jia Hu , Hui-Zi Jin , Wei-Dong Zhang , Wei Zhang , Shi-Kai Yan , Run-Hui Liu , Yun-Heng Shen and Wen-Zheng Xu
  Two new coumarins, 8-[3-(2,4-benzenediol)-propionic acid methyl ester]-coumarin-7-β-D-glucoside (1) and 7-hydroxyl-odesmethoxyrutarensin (2), were isolated from the stems and barks of Edgeworthia chrysantha. Their structures were elucidated on the basis of spectroscopic data interpretation.
  Yu Liu , Zheng Li and Wei Zhang
  This paper presents a crack detection method for fibre reinforced composite beams based on the continuous wavelet transform. Finite element method simulations and experiments were carried out for flawed cantilever composite beams subjected to impact load at their free ends. The Gabor and Morlet wavelets were chosen for wave signal processing owing to their good time-frequency characteristics. Both wavelets perform well in the crack detection of composite beams. The results show that the crack location can be determined successfully, and the crack depth can be estimated from the crack-reflection ratio. Moreover, the Gabor wavelet can locate the cracks more accurately by virtue of its higher time resolution.
  Hua Wang , Zheng-zhi Han , Wei Zhang and Qi-yue Xie
  Chaos synchronization in unified chaotic systems with uncertain parameters is discussed in this paper. On the basis of the control Lyapunov function (CLF), a feedback controller is designed which is only related to the boundaries of the uncertain parameters. Synchronization of two identical unified chaotic systems with different initial conditions is realized. Simulation results for Lorenz, Lü and Chen chaotic systems are provided to verify the effectiveness of the proposed scheme.
  Ling Zhao , Kaiyu Wang , Qingjiao Liao , Rui Zhang and Wei Zhang
  In order to maximize the yield of polysaccharides of Catathelasma ventricosum, response surface methodology was applied to optimize the extraction conditions (extraction temperature, ratio of water to raw material and extraction time) of polysaccharides from the fruiting bodies of Catathelasma ventricosum. A box-behnken design was used for experimental design and analysis of the results to obtain the optimal processing parameters. Among the three extraction parameters, the extraction temperature was the most significant factor to affect the yield of polysaccharides from Catathelasma ventricosum. A mathematical model with high determination coefficient was gained and could be employed to optimize polysaccharides extraction and the optimal conditions were extraction temperature 100°C, ratio of water to raw material 22.78:1, extraction time 3.66 h. Under these conditions, the experimental yield of polysaccharide was 6.47±0.14% which was close to the predicted value.
  Wei Zhang , Dong Wang , Elzi Volk , Hugo J. Bellen , Peter Robin Hiesinger and Florante A. Quiocho
  The V<SUB>0</SUB> complex forms the proteolipid pore of a vesicular ATPasethat acidifies vesicles. In addition, an independent functionin membrane fusion has been suggested in vacuolar fusion inyeast and synaptic vesicle exocytosis in fly neurons. Evidencefor a direct role in secretion has also recently been presentedin mouse and worm. The molecular mechanisms of how the V<SUB>0</SUB> componentsmight act or are regulated are largely unknown. Here we reportthe identification and characterization of a calmodulin-bindingsite in the large cytosolic N-terminal region of the <I>Drosophila</I>protein V100, the neuron-specific V<SUB>0</SUB> subunit a1. V100 formsa tight complex with calmodulin in a Ca<SUP>2+</SUP>-dependent manner.Mutations in the calmodulin-binding site in <I>Drosophila</I> leadto a loss of calmodulin recruitment to synapses. Neuronal expressionof a calmodulin-binding deficient V100 uncovers an incompleterescue at low levels and cellular toxicity at high levels. Ourresults suggest a vesicular ATPase V<SUB>0</SUB>-dependent function ofcalmodulin at synapses.
  Zongdong Li , Michael A. Nardi , Jing Wu , Ruimin Pan , Wei Zhang and Simon Karpatkin
  We have described an autoantibody against β3 (GPIIIa49–66), a region of platelet integrin αIIbβ3 that is unique. It induces platelet fragmentation in the absence of complement via antibody activation of platelet NADPH oxidase and 12-lipoxygenase to release reactive oxygen species, which destroy platelets. To study the mechanism of anti-GPIIIa antibody-induced platelet fragmentation, we screened a human single chain Fv antibody library with the GPIIIa49–66 peptide. Nine monoclonal antibodies were identified that were capable of binding to GPIIIa49–66. Surprisingly, binding avidity for GPIIIa49–66 did not correlate with activity of induction of platelet fragmentation. We therefore investigated the requirements for platelet fragmentation. Mutations were introduced into the heavy chain complementary-determining region-3 of clones 11, 43, and 54 by site-directed mutagenesis. The capability of these clones to induce platelet fragmentation or bind to GPIIIa49–66 subsequently changed. Molecular modeling of these clones with their mutants revealed that the ability to induce platelet fragmentation is affected by the side chain orientation of positively charged amino acids in the heavy chain of residues 99–102. Thus, a structural change in the conformation of anti-GPIIIa49–66 antibody contributes to its binding to the β3 integrin and subsequent antibody-induced platelet fragmentation and aggregate dissolution.
  Yanwu Yang , Wei Zhang , James R. Bayrer and Michael A. Weiss
  The DSX (Doublesex) transcription factor regulates somatic sexual differentiation in Drosophila. Female and male isoforms (DSXF and DSXM) are formed due to sex-specific RNA splicing. DNA recognition, mediated by a shared N-terminal zinc module (the DM domain), is enhanced by a C-terminal dimerization element. Sex-specific extension of this element in DSXF and DSXM leads to assembly of distinct transcriptional preinitiation complexes. Here, we describe the structure of the extended C-terminal dimerization domain of DSXF as determined by multidimensional NMR spectroscopy. The core dimerization element is well ordered, giving rise to a dense network of interresidue nuclear Overhauser enhancements. The structure contains dimer-related UBA folds similar to those defined by x-ray crystallographic studies of a truncated domain. Whereas the proximal portion of the female tail extends helix 3 of the UBA fold, the distal tail is disordered. Ala substitutions in the proximal tail disrupt the sex-specific binding of IX (Intersex), an obligatory partner protein and putative transcriptional coactivator; IX-DSXF interaction is, by contrast, not disrupted by truncation of the distal tail. Mutagenesis of the UBA-like dimer of DSXF highlights the importance of steric and electrostatic complementarity across the interface. Two temperature-sensitive mutations at this interface have been characterized in yeast model systems. One weakens a network of solvated salt bridges, whereas the other perturbs the underlying nonpolar interface. These mutations confer graded gene-regulatory activity in yeast within a physiological temperature range and so may provide novel probes for genetic analysis of a sex-specific transcriptional program in Drosophila development.
  Jacob C. Garza , Ming Guo , Wei Zhang and Xin-Yun Lu
  Leptin, an adipose-derived hormone, has been implicated in several physiological processes involving the hippocampus. However, the role of leptin in adult hippocampal neurogenesis remains unknown. Here we show that leptin regulates neurogenesis in the dentate gyrus of adult mice as well as in cultured adult hippocampal progenitor cells. Chronic administration of leptin to adult mice increased cell proliferation without significant effects on the differentiation and the survival of newly proliferated cells in the dentate gyrus. The expression of the long form leptin receptor, LepRb, was detected in hippocampal progenitor cells by reverse transcription-PCR and immunohistochemistry. Leptin treatment also increased proliferation of cultured adult hippocampal progenitor cells. Analysis of signal transduction pathways revealed that leptin stimulated phosphorylation of Akt and STAT3 but not ERK1/2. Furthermore, pre-treating the cells with specific inhibitors of Akt or STAT3 attenuated leptin-induced cell proliferation in a dose-dependent manner. Taken together, our results support a role for leptin in adult hippocampal neurogenesis and suggest the involvement of the Akt and STAT3 signaling pathways in mediating the actions of leptin on neurogenesis.
  Zhao Wu , Wei Zhang , Guibin Chen , Lu Cheng , Jing Liao , Nannan Jia , Yuan Gao , Huiming Dai , Jinduo Yuan , Linzhao Cheng and Lei Xiao
  Cell fate commitment of pre-implantation blastocysts, to either the inner cell mass or trophoblast, is the first step in cell lineage segregation of the developing human embryo. However, the intercellular signals that control fate determination of these cells remain obscure. Human embryonic stem cells (hESCs) provide a unique model for studying human early embryonic development. We have previously shown that Activin/Nodal signaling contributes to maintaining pluripotency of hESCs, which are derivatives of the inner cell mass. Here we further demonstrate that the inhibition of Activin/Nodal signaling results in the loss of hESC pluripotency and trophoblast differentiation, similar to BMP4-induced trophoblast differentiation from hESCs. We also show that the trophoblast induction effect of BMP4 correlates with and depends on the inhibition of Activin/Nodal signaling. However, the activation of BMP signaling is still required for trophoblast differentiation when Activin/Nodal signaling is inhibited. These data reveal that the early lineage segregation of hESCs is determined by the combinatorial signals of Activin/Nodal and BMP.
  Bobby Bhatia , Ming Jiang , Mahipal Suraneni , Lubna Patrawala , Mark Badeaux , Robin Schneider-Broussard , Asha S. Multani , Collene R. Jeter , Tammy Calhoun-Davis , Limei Hu , Jianhua Hu , Spiridon Tsavachidis , Wei Zhang , Sandy Chang , Simon W. Hayward and Dean G. Tang
  Normal human prostate (NHP) epithelial cells undergo senescence in vitro and in vivo, but the underlying molecular mechanisms remain obscure. Here we show that the senescence of primary NHP cells, which are immunophenotyped as intermediate basal-like cells expressing progenitor cell markers CD44, α2β1, p63, hTERT, and CK5/CK18, involves loss of telomerase expression, up-regulation of p16, and activation of p53. Using genetically defined manipulations of these three signaling pathways, we show that p16 is the primary determinant of the NHP cell proliferative capacity and that hTERT is required for unlimited proliferative life span. Hence, suppression of p16 significantly extends NHP cell life span, but both p16 inhibition and hTERT are required to immortalize NHP cells. Importantly, immortalized NHP cells retain expression of most progenitor markers, demonstrate gene expression profiles characteristic of proliferating progenitor cells, and possess multilineage differentiation potential generating functional prostatic glands. Our studies shed important light on the molecular mechanisms regulating the proliferative life span of NHP progenitor cells.
 
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