A comparative study on rat intestinal epithelial cells and resident gut bacteria (ii) effect of arsenite / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>In order to use facultative gut bacteria as an alternate to animals for the initial gastrointestinal toxicity screening of heavy metals, a comparative study on rat intestinal epithelial cells and resident gut bacteria was undertaken.</p><p><b>METHODS</b>in vitro growth rate of four gut bacteria, dehydrogenase (DHA) and esterase (EA) activity test, intestinal epithelial and bacterial cell membrane enzymes and in situ effect of arsenite were analysed.</p><p><b>RESULTS</b>Growth profile of mixed resident population of gut bacteria and pure isolates of Escherichia coli, Pseudomonas sp., Lactobacillus sp., and Staphylococcus sp. revealed an arsenite (2-20 ppm) concentration-dependent inhibition. The viability pattern of epithelial cells also showed similar changes. DHA and EA tests revealed significant inhibition (40%-72%) with arsenite exposure of 5 and 10 ppm in isolated gut bacteria and epithelial cells. Decrease in membrane alkaline phosphatase and Ca2+ -Mg2+ -ATPase activities was in the range of 33%-55% in four bacteria at the arsenite exposure of 10 ppm, whereas it was 60%-65% in intestinal epithelial villus cells. in situ incubation of arsenite using intestinal loops also showed more or less similar changes in membrane enzymes of resident gut bacterial population and epithelial cells.</p><p><b>CONCLUSION</b>The results indicate that facultative gut bacteria can be used as suitable in vitro model for the preliminary screening of arsenical gastrointestinal cytotoxic effects.</p>

Seroprevalence of three emerging arboviral infections in Kuwaiti nationals

Diseases caused by dengue, s and fly fever and hanta viruses pose a major health risk in many countries. We determined the threat of these arboviral infections through a serologic using enzyme linked immunosorbent assay [ELISA] based tests. Hantavirus-specific antibodies were also detected using immunofluorescence. Of 499 samples tested for dengue virus IgG antibodies l4% were as positive for dengue positive by all the ELISA tests. Among the 42 showing strong IgG reactivity, only 1 was positive for dengue virus IgM antibodies. All samples tested for IgG antibodies to s and fly fever virus were negative. Hantavirus antibodies were detected in 11% of the 46 samples from high-risk individuals. The low prevalences suggest that at present these infections are not a serious problem in Kuwait

Respiratory burst by dengue-virus-induced cytotoxic factor

This study investigates the induction and release of the superoxide anion [O-2] and hydrogen peroxide [H2O2] by mouse spleen cells on stimulation with dengue type 2 virus [DV] and a DV-induced cytokine, the cytotoxic factor [mCF]. Normal mice or their spleen cell cultures were inoculated with DV or mCF. At different time periods, the spleen cell supernatants were assayed for the production of O-2 and H2O2. Inoculation of DV in spleen cell cultures resulted in peak production of O-2 and H2O2 at 48 and 72 h, respectively, while in DV-infected mouse spleen, the maximum production was on days 7 and 8, which correlated with the appearance of mCF in the milieu. Maximum O-2 and H2O2 production occurred at 45 min and 1 h after inoculation of 5 micro g of mCF. Pretreatment of mCF with anti-mCF-antiserum inhibited O-2 and H2O2 release indicating the specificity of the induction by mCF. The enriched subpopulations of macrophages and T cells produced O-2 and H2O2 and not B cells. Treatment of the cells with superoxide dismutase increased H2O2 release but inhibited O-2 release and the cytotoxicity in a dose-dependent manner. This showed that O-2 is responsible for the cytotoxic activity of mCF and not H2O2. In conjunction with our earlier findings that pretreatment with NG-monomethyl-L-arginine inhibited mCF-induced production of NO and the cytotoxicity, it is concluded that the presence of both O-2 and NO is required for the cytotoxic activity of mCF, thereby indicating a possible role of peroxynitrite