Quantitative specific detection of Staphylococcus aureus is based on recombinant lysostaphin and ATP bioluminescence. To produce recombinant lysostaphin, the lysostaphin gene was chemically synthesized and inserted it into prokaryotic expression vector pQE30, and the resulting expression plasmid pQE30-Lys was transformed into E. coli M15 for expressing lysostaphin with IPTG induction. The recombinant protein was purified by Ni(2+)-NTA affinity chromatography. Staphylococcus aureus was detected by the recombinant lysostaphin with ATP bioluminescence, and plate count method. The results of the two methods were compared. The recombinant lysostaphin was successfully expressed, and a method of quantitative specific detection of S. aureus has been established, which showed a significant linear correlation with the colony counting. The detection method developed has good perspective to quantify S. aureus.
Adenosine Triphosphate ; chemistry ; Chromatography, Affinity ; Escherichia coli ; Luminescent Measurements ; methods ; Lysostaphin ; chemistry ; Recombinant Proteins ; chemistry ; Staphylococcus aureus ; isolation & purification

Objective To study the immunoreaction of the recombinant proteins encoded by the fragments of ORF2 ( second open reading frames) gene of hepatitis E virus ( HEV). Methods The aimed sequence from the full-length ORF2 in clone PEH2 , which was derived from a Chinese strain of HEV,was amplified and cloned it into vector pcDNAS. 1 which was then transfected to 293 cell. Results The ORF2 protein was present in the soluble fractions of the cell lysate. The expressed protein of HEV ORF2 in 293 cells by using a plasmid pcDNA3. 1-based system showed positive on immunoblots probed against antibodies raised in BALB/c mice. Conclusion The experimental results laid a foundation for developing diagnostic reagent to detect HEV by using the expressed products of ORF2 protein.

Objective Compare the reproductive activity of pancreatic stem cells isolated from diabetic rat with that of normal rat to assess the effect of microenvirement on stem cells'proliferation.Methods Diabetic rat model were prepared by peritoneal injecting 60mg/kg streptozotocin.Pancreata from 10 diabetic rats and 10 normal rats were trimmed and digested into single cells which were then inoculated onto the culture plate respectively.After passaging 3 generation the cells were identified by nestin immunostaining.During culturing the cell growth curve was observed and the cell cycle of the third and seventh generation cultured cells was evaluated by flow cytometry.Results After passaging pancreatic stem cells was purified and identified by nestin immunostaining.The reproductive activity of diabetic rat was much better[ratio of s stage:(20.7?2.7)% vs(14.1?2.5)%,P0.05].Conclusions The stem cells are stimulated to proliferate after islet injure.The reproductive activity of cells can be provoked by the microenvironment.

A simple rapid detection of antibody to hepatitis delta virus (anti-HDV) in human serum was developed by using double antigen sandwich ELISA. HDV gene fragment encoding HDAg was isolated from a Chinese patient infected with HDV by RT-PCR, and a high-efficient expression HD-PQE31 strain was constructed with the fragment. We obtained high titer and good quality hepatitis delta virus protein purified by Ni-NTA metal-affinity chromatography, which was identified by Western blot and ELISA, then we set up the double antigen sandwich ELISA for detection of anti-HDV in human serum, and the performance of the sandwich ELISA was evaluated in terms of specificity and sensitivity. Results were: 1) The purified HDAg protein's purity was 90%, and its ELISA titer was 1/100 000. 2) 42 anti-HDV positive sera were detected and showed that the sensitivity of sandwich ELISA was higher than that of competitive ELISA (t=2.44, p<0.01). 3) The inhibitory rates for 2 anti-HDV positive sera by the specific HDAg were 74% and 93% respectively. 4) For the assay of specificity, all 60 samples infected by other hepatitis viruses and 30 normal samples were negative for anti-HDV. These results suggested that the double antigen sandwich ELISA with purified recombinant HDAg showed higher specificity and sensitivity, It can be used in routine laboratories to diagnose the HDV infection.

Objective To establish a mouse model of acute liver failure induced by lipopolysaccharide /D-galac-tosamine ( LPS/D-GalN) .Methods The optimum dose of LPS/D-GalN was determined by i .p.injection of eight differ-ent doses of LPS and D-GalN into 40 female C57BL/6 mice and observation of their survival time .Then, 32 female C57BL/6 mice were i.p.injected with the optimal dose of LPS/D-GalN and sacrificed at 0, 1, 4, 8 hours after the injec-tion, 8 mice in each group.The control mice received saline injection .Hepatic changes were observed by pathology and se-rum ALT, IL-6, MCP-1 and TNF-αwere measured by biochemistry or flow cytometry .Results LPS (2.5 mg/kg) and D-GalN (0.3 g/kg) were determined as the optimal dose for the establishment of mouse model of acute liver injury .Com-pared with the control group , the hepatocellular damages were progressing in a positive correlation with the time course after LPS/D-GalN administration .The level of serum ALT was significantly increased after LPS/D-GalN administration ( P <0.001).The levels of inflammatory cytokines IL-6, MCP-1 and TNF-αwere increased and reached a peak at one hour after LPS/D-GalN administration and then decreased almost to that of the control group 8 hours later(P<0.001).Conclusions The mouse model of acute liver injury is successfully established by LPS /D-GalN administration , and provide an effective animal model for the study of pathogenic mechanisms of acute liver failure and evaluation of therapeutic drugs .

Objective To explore the association of ubiquitin-specific proteases 24 (USP24) gene polymorphisms with susceptibility to sporadic Parkinson's disease (PD) in the Han Guangdong population. Methods From August, 2006 to January, 2014, single nucleotide poly-morphisms (SNPs) of rs12138592 and rs6671533 in the intron region of USP24 were genotyped in 200 patients with sporadic PD and 200 healthy controls using the SNaPshot technique. Results There was significant difference in the allele and genotype frequency of rs12138592 between the patients and the controls (P<0.01), and no significant difference was found in the allele and genotype frequency of rs6671533 (P>0.05). Conclusion The SNP of rs12138592 in the intron region of USP24 is associated with the susceptibility to sporadic PD in the Han Guangdong population, and the A allele may contribute a protective roles to PD.

Objective To investigate the effects of glutamate receptor signaling on melanoma cell dendrite morphology and cytoskeleton protein. Methods A metastatic human malignant melanoma cell line WM451LU was cultured and transfected by recombinant adenovirus vector carrying a cDNA encoding microtubule-associated protein 2a (MAP2a). MK-801, an antagonist of N-methyl-D-aspartate receptor (NMDAR), and CPCCOEt, an antagonist of metabotropie glutamate receptor 1 (mGluR1), were used to treat transfected or untrausfeeted WM451LU cells. Confocal microscopy and three dimensional atomic force microscopy were used to assess subcellular location of NMDAR2A, mGluR1 and MAP2a as well as the dis-tribution of α-tubulin in and dendrite morphology of WM451LU cells. The proliferation of WM451LU cells was estimated by cell survival growth curve. Results Confocal laser microscopy revealed that NMDAR2A, mGluRl and MAP2a were mainly co-localized in melanoma cell dendrites. Both MK-801 and CPCCOEt increased the density of microtubules in cell dendrites and dendritic branching of WM451LU cells, and both effects of MK-801 and CPCCOEt were enhanced by the expression of MAP2a. Furthermore, the proliferation of WM451LU cells was significantly inhibited by MK-801 of 100 μmol/L and CPCCOEt of 10 μmol/L. Conclusions In melanoma cells, glutamate receptors may participate in the development of dendrites, and anta- gonists of glutamate receptors could inhibit the proliferation of melanoma cells.

OBJECTlVE To study the anti-HBV activity of prepared recombinant human serum aIbu-min-interferon α-2b fusion protein(HSA-IFNα-2b) in vitro. METHODS HepG2 ceIIs were infected with recombinant adenovirus with green fIuorescence protein and 1.6-foId HBV DNA(AdGFP-HBV). The ex-pression of HBV antigens,HBsAg and HBeAg in cuIture medium was detected by ELISA assay. The tox-icity of HSA-IFNα-2b on HepG2 ceIIs was evaIuated by mTT assay.The reIative expression of HBV RNA in ceIIs and the absoIute quantity of HBV DNA in cuIture supernatant were determined by quantitative PCR assay. The activity of HBV enhancer Ⅰ was detected by DuaI-Reporter gene assay. RESULTS HBV couId repIicate and express in HepG2 ceIIs after infection with AdGFP-HBV. The expression of HBsAg and HBeAg in cuIture serum of HepG2 ceIIs infected with AdGFP-HBV decreased by 51.32%(P﹤0.01)and 50.26%(P﹤0.01),respectiveIy,when HSA-IFNα-2b 500 kU·L-1 was added. The same concentration of HSA-IFNα-2b didn't inhibit the proIiferation of HepG2 ceIIs,but inhibited HBsAg in a concentration-dependent manner. The regression formuIa between HBsAg inhibitory rate(Y)and con-centration of HSA-IFNα-2b(X)was Y=21.11 IgX+11.91(r 2 = 0.954),IC50 = 63.76 kU·L-1 . HBV RNA in ceIIs and HBV DNA in the cuIture serum decreased by 52.83%(P﹤0.01)and 53.07%(P﹤0.01), respectiveIy,when HSA-IFNα-2b 500 kU·L-1 was added. The activity of enhancer Ⅰ decreased by 40.04%(P﹤0.01)when HSA-IFNα-2b 500 kU·L-1 was added. CONCLUSlON The ceII modeI of HBV repIication for evaIuating anti-HBV agents is successfuIIy estabIished. HSA-IFNα-2b exhibits noticeabIe anti-HBV effect invitro.

Objective To establish a simple and quick loop-mediated isothermal amplification (LAMP)method for detection of Yersinia pestis.Methods LAMP Primers were designed based on the specific sequence 3a in Y.pestis chromosome.LAMP reaction results were detected using turbidity meter or visual method.The specificity of the constructed method was evaluated by detecting Y.pestis and its closely-related bacteria.The different dilution DNA template was detected with LAMP and PCR to evaluate the sensitivity of the method.Results Thirty strains of bacteria closely related to Y.pestis were detected by the constructed LAMP,and all the results were negative,indicating that the method had a very high specificity.The detection sensitivity of this LAMP assay was 20 pg of DNA per reaction,which was ten-fold that of the regular PCR.The detection reaction was completed in 25 min.Conclusion This LAMP method is quick,sensitive, specific and simple,which is expecked to become an effective method for rapid detection of Y.pestis on the scene.

Objective To express a recombinant protein TFPR1 ( the functional region of the snake venom proteins from Trimeresurus flavoviridis) in Pichia pastoris expression system. Methods The target gene was codon-optimized and synthesized according to the sequence of the conserved structural do-main of triflin and then cloned into the Pichia pastoris expression vector pPICZαA to construct the recombi-nant expression plasmid pPICZαA-TFPR1. The recombinant plasmid pPICZαA-TFPR1 was electroporated into the yeast strain X33. The transformed strains carrying expression plasmid were screened out with Zeocin and then induced by methanol to express the recombinant protein TFPR1. ELISA was performed for the screening of positive clones. SDS-PAGE and Western blot were used for further identification of the ex-pressed products. Results The recombinant plasmid pPICZαA-TFPR1 was successfully constructed. The recombinant protein TFPR1 was expressed in a secreted form at a molecular weight of 16×103. Conclusion The recombinant protein TFPR1 was successfully expressed in Pichia pastoris expression system, which laid a foundation for further researches on its biological function and application as an adjuvant.