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Articles by X Shi
Total Records ( 4 ) for X Shi
  C Meng , X Peng , X Shi , H Wang and Y. Guo
 

In this study, a chemically modified homo zwitterionic polysaccharide (ZPS), sulfated chitosan, was used to examine its effects on murine immune response. The results showed that homoZPS could markedly promote the proliferation of both splenic T/B cells and adhesive cells. In particular, flow cytometry assay demonstrated that the sulfated chitosan could non-specifically activate CD3+ and CD8+ T cells proliferation in vitro. The effectiveness of sulfated chitosan as adjuvant was tested using bovine serum albumin (BSA) and diphtheria toxin (DT) as antigens and compared with that of aluminum hydroxide. The levels of specific antibodies to BSA and DT significantly increased after homoZPS vaccination. Both homoZPS and aluminum hydroxide adjuvants could protect mice against the attack of DT from edemas of spleen and tail. The present findings demonstrated the chemically derived homoZPS could be a potential candidate in the development of T-lymphocyte dependent vaccine adjuvants.

  X Wu , W Zhang , X Shi , P An , W Sun and Z. Wang
 

In this study, we investigated the therapeutic effect of artemisinin (Art) on lupus nephritis mice and its mechanisms by comparing the differences between lupus nephritis (LN) mice given Art and control mice in molecular biology, immunohistochemistry, and histopathology. The results showed that Art could remarkably relieve the symptoms, decrease the level of urine protein/24 h, and alleviate pathological renal lesions. The differences among the four groups in the expression of the NF-Bp65 protein, nuclear factor-B (NF-B) activity, and the expression of transforming growth factor-β1 (TGF-β1) mRNA in renal tissue suggested that Art can lower the serum levels of tumor necrosis factor- (TNF-) and interleukin-6 (IL-6) and inhibit the expression of the NF-Bp65 protein and NF-B and TGF-β1 mRNA in the renal tissues of LN mice. These results proved that it is reliable and effective to use Art to treat LN mice, and its therapeutic mechanisms should closely be related to the fact that Art can obviously decrease the serum levels of TNF- and IL-6 and down-regulate the expression of the NF-Bp65 protein and NF-B and TGF-β1 mRNA in renal tissues.

  G Fan , C Feng , Y Li , C Wang , J Yan , W Li , J Feng , X Shi and Y. Bi
 

Background: We carried out animal experiments based on the orthogonal design L8(27) setting seven factors with two different levels of each and 10 groups of rats. The nutrients tested were tyrosine, glycine, methionine, taurine, ascorbic acid, thiamine and zinc.

Objectives: The objective of this study was to explore the optimal combinations of nutrients for prevention or amelioration of lead-induced learning and memory impairment.

Methods: Rats were supplemented with nutrients by gavage once a day in two experiments: one was simultaneous nutrient supplementation with lead acetate administration (800 mg l–1) for 8 weeks (prophylactic supplementation) and the other was nutrient supplementation for 4 weeks after the cessation of 4 weeks of lead administration (remedial supplementation). Morris water maze was initiated at ninth week. Rats were terminated for assays of levels of Pb in blood, activities of superoxide dismutase (SOD) and nitric oxide synthase (NOS) in hippocampus, levels of nitric oxide (NO) in hippocampus and expressions of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and cyclic adenosine monophosphate (cAMP) response element-binding protein messenger RNA in hippocampus.

Results: Results showed that in prophylactic supplementation, methionine, taurine, zinc, ascorbic acid and glycine were the effective preventive factors for decreasing prolonged escape latency, increasing SOD and NOS activities and NO levels in the hippocampus, respectively. On the other hand, in remedial supplementation, taurine was the effective factor for reversing Pb-induced decrease in activities of SOD, NOS and levels of NO.

Conclusions: In conclusion, the optimum combinations of nutrients appear to be methionine, taurine, zinc, ascorbic acid and glycine for the prevention of learning and memory impairment, while taurine and thiamine appear to be the effective factors for reversing Pb neurotoxicity.

  X Shi , C Shao , X Zhang , C Zambonelli , A. G Redfield , J. F Head , B. A Seaton and M. F. Roberts
 

Cleavage of phosphatidylinositol (PI) to inositol 1,2-(cyclic)-phosphate (cIP) and cIP hydrolysis to inositol 1-phosphate by Bacillus thuringiensis phosphatidylinositol-specific phospholipase C are activated by the enzyme binding to phosphatidylcholine (PC) surfaces. Part of this reflects improved binding of the protein to interfaces. However, crystallographic analysis of an interfacially impaired phosphatidylinositol-specific phospholipase (W47A/W242A) suggested protein dimerization might occur on the membrane. In the W47A/W242A dimer, four tyrosine residues from one monomer interact with the same tyrosine cluster of the other, forming a tight dimer interface close to the membrane binding regions. We have constructed mutant proteins in which two or more of these tyrosine residues have been replaced with serine. Phospholipid binding and enzymatic activity of these mutants have been examined to assess the importance of these residues to enzyme function. Replacing two tyrosines had small effects on enzyme activity. However, removal of three or four tyrosine residues weakened PC binding and reduced PI cleavage by the enzyme as well as PC activation of cIP hydrolysis. Crystal structures of Y247S/Y251S in the absence and presence of myo-inositol as well as Y246S/Y247S/Y248S/Y251S indicate that both mutant proteins crystallized as monomers, were very similar to one another, and had no change in the active site region. Kinetic assays, lipid binding, and structural results indicate that either (i) a specific PC binding site, critical for vesicle activities and cIP activation, has been impaired, or (ii) the reduced dimerization potential for Y246S/Y247S/Y248S and Y246S/Y247S/Y248S/Y251S is responsible for their reduced catalytic activity in all assay systems.

 
 
 
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