pR_(ST98) is a large and conjugative resistant plasmid(R plasmid)of 98.6 mega-dalton from multi-drug resistant Salmonella typhi(S.typhi),which was classified to incompatibility group C(Inc C).It has been found that pR...pR_(ST98) is a large and conjugative resistant plasmid(R plasmid)of 98.6 mega-dalton from multi-drug resistant Salmonella typhi(S.typhi),which was classified to incompatibility group C(Inc C).It has been found that pR_(ST98) made its host bacteria not only antibiotic resistant but also more virulent.In this study we explored the possibility of plasmid pR_(ST98) in S.typhi carrying the Salmonella plasmid virulence gene-spv.The plasmid pR_(ST98) was isolated, purified and then digested by nine restriction endonucleases to make the plasmid enzyme profile.Spv-specific PCR and Southern blot were applied to identify the virulence gene on pR_(ST98).The amplified spv fragments spvR and spvB were cloned into pGEM-T EASY and then the DNA sequences were analysed.The fragments of pR_(ST98) digested by endonucleases Bgl Ⅱ,Pst Ⅰ and Sac Ⅱ were identified,which may be useful for molecular analysis and further epidemiological surveillance of pR_(ST98).The results of PCR and Southern blot showed that spv homologous genetic sequence which had been found in all pathogenesis Salmonella spp.except S.typhi was also presented on pR_(ST98).The ORF of spvR and spvB of pR_(ST98) were 894 bp and 1,776 bp,respectively.They have more than 99% homology with that of spvR and spvB on virulence plasmid in S.typhmurium.The genotype research on pR_(ST98) revealed that there is a plasmid carrying genes responsible for drug resistance and virulence in S.typhi.This is the first report for such kind chimerical plasmid in S.typhi.Cellular & Molecular Immunology.2005;2(2):136-140.展开更多
Increased expression of Fas by hematopoietic progenitors in aplastic anemia(AA)suggests that Fas/Fas ligand (FasL)system plays a key role in the formation of severe pancytopenia.To further confirm the above hypo- thes...Increased expression of Fas by hematopoietic progenitors in aplastic anemia(AA)suggests that Fas/Fas ligand (FasL)system plays a key role in the formation of severe pancytopenia.To further confirm the above hypo- thesis,T cells from 8 patients with AA were systematically studied for their FasL's distribution pattern, releasing manner and proapoptotic activity,compared with normal resting T cells and artificially activated T cell blasts.The results demonstrated that AA T cells abnormally expressed low levels of membrane-bound FasL and contained high levels of intracellular FasL which could be triggered to release by high-dose phyto- hemagglutinin(PHA)pulse-stimulation.The supernatants from the PHA-stimulated AA T cells had apparent cytotoxicity against FasL-sensitive Jurkat cells,which could be significantly inhibited by monocional antibody against FasL in a dose-dependent manner,or nearly completely abrogated by ultracentrifugation.The above phenomena also appeared on artificially activated T cell blasts,but this was not the case on normal resting T cells.These results indicate that AA T cell is a type of“preactivated”T lymphocyte,characterized by over- expression of FasL,especially intracellular FasL which can be stimulated to release in bioavtive exosomes- bound form.Taken together,our data provide further and direct evidence for the hypothesis that T cells might mediate the destruction of hematopietic progenitor in AA through Fas/FasL system.Cellular & Molecular Immunology.2004;1(2):142-147.展开更多
文摘pR_(ST98) is a large and conjugative resistant plasmid(R plasmid)of 98.6 mega-dalton from multi-drug resistant Salmonella typhi(S.typhi),which was classified to incompatibility group C(Inc C).It has been found that pR_(ST98) made its host bacteria not only antibiotic resistant but also more virulent.In this study we explored the possibility of plasmid pR_(ST98) in S.typhi carrying the Salmonella plasmid virulence gene-spv.The plasmid pR_(ST98) was isolated, purified and then digested by nine restriction endonucleases to make the plasmid enzyme profile.Spv-specific PCR and Southern blot were applied to identify the virulence gene on pR_(ST98).The amplified spv fragments spvR and spvB were cloned into pGEM-T EASY and then the DNA sequences were analysed.The fragments of pR_(ST98) digested by endonucleases Bgl Ⅱ,Pst Ⅰ and Sac Ⅱ were identified,which may be useful for molecular analysis and further epidemiological surveillance of pR_(ST98).The results of PCR and Southern blot showed that spv homologous genetic sequence which had been found in all pathogenesis Salmonella spp.except S.typhi was also presented on pR_(ST98).The ORF of spvR and spvB of pR_(ST98) were 894 bp and 1,776 bp,respectively.They have more than 99% homology with that of spvR and spvB on virulence plasmid in S.typhmurium.The genotype research on pR_(ST98) revealed that there is a plasmid carrying genes responsible for drug resistance and virulence in S.typhi.This is the first report for such kind chimerical plasmid in S.typhi.Cellular & Molecular Immunology.2005;2(2):136-140.
基金supported by grants from National Key Basic Research Program of China("973"project)(No.2001CB510003)Basic scientific research program foundation of the Commission of Science Technology an d Industry for National Defence(2003-44)Key Medical Elite Foundation of Jiangsu Provincial Govemment(No.RC2002021)
文摘Increased expression of Fas by hematopoietic progenitors in aplastic anemia(AA)suggests that Fas/Fas ligand (FasL)system plays a key role in the formation of severe pancytopenia.To further confirm the above hypo- thesis,T cells from 8 patients with AA were systematically studied for their FasL's distribution pattern, releasing manner and proapoptotic activity,compared with normal resting T cells and artificially activated T cell blasts.The results demonstrated that AA T cells abnormally expressed low levels of membrane-bound FasL and contained high levels of intracellular FasL which could be triggered to release by high-dose phyto- hemagglutinin(PHA)pulse-stimulation.The supernatants from the PHA-stimulated AA T cells had apparent cytotoxicity against FasL-sensitive Jurkat cells,which could be significantly inhibited by monocional antibody against FasL in a dose-dependent manner,or nearly completely abrogated by ultracentrifugation.The above phenomena also appeared on artificially activated T cell blasts,but this was not the case on normal resting T cells.These results indicate that AA T cell is a type of“preactivated”T lymphocyte,characterized by over- expression of FasL,especially intracellular FasL which can be stimulated to release in bioavtive exosomes- bound form.Taken together,our data provide further and direct evidence for the hypothesis that T cells might mediate the destruction of hematopietic progenitor in AA through Fas/FasL system.Cellular & Molecular Immunology.2004;1(2):142-147.
