Effect of different stress conditions on growth and biofilm formation capability of Enterococcus faecalis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the changes of growth and biofilm formation capability of Enterococcus faecalis (Ef) in different stress conditions.</p><p><b>METHODS</b>The changes of growth of Ef in stress conditions were observed by measuring the A600 value with ultraviolet spectrophotometer. Ef was incubated on glass slide in stress conditions, biofilm formation capability of cells was investigated by colony-forming unit (CFU) counting of the culturable bacteria and fluorescence confocal laser scanning microscopy.</p><p><b>RESULTS</b>Ef couldn't growth under the conditions of 2%, 5%NaClO, pH = 11 and 12, the A600 value was unchanged in 96 hours. But the growth curve changed at different levels in other stress conditions: under 1%NaClO, the A600 value peaked at 1.461 at 16 hour (the peaked level was 1.238 at 6 hours in control group) ; under 0,0.05%,0.15% glucose, it peaked at 0.645,0.890, 1.173, respectively, at 6 hour (it was maximized to 1.195 at 6 hours in control group); the A600 value peaked at 1.704 at 6 hours at pH = 9 and 1.225 at 10 hours at pH = 10 (the peak level was 1.732 at 6 hours at pH = 7) . Biofilm assay showed that Ef were able to form biofilm in these stress conditions except 5%NaClO and pH = 12.</p><p><b>CONCLUSIONS</b>Ef could growth and form biofilms in energy starvation, low concentrations of sodium hypochlorite and weak alkaline stress.</p>

Expression of Toll-like receptors in mononuclear cells from children with acute rotavirus diarrhea / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>Rotavirus is the single most common cause of severe dehydrating diarrhea in young children worldwide, but the pathogenesis and immunity against this disease are not completely understood. A prospective study was conducted to assess gene expression of toll-like receptors (TLR) in children with acute rotavirus diarrhea.</p><p><b>METHODS</b>Seventy-five children with acute rotavirus diarrhea and 38 control children were enrolled in this study from Sep. 2004 to Jan. 2005. All the 75 patients had detailed records of clinical characteristics. Rotavirus antigen was detected by ELISA from stools. Peripheral blood mononuclear cells (PBMC) were separated by Ficoll reagent and RNA was extracted by Trizol. The levels of mRNA for five TLRs in PBMC were examined by fluorescent quantitative RT-PCR.</p><p><b>RESULTS</b>Patients with acute rotavirus infection had elevated mean levels of TLR 2, 3, 4, 7, 8 mRNA expressions in PBMC within 3 days since onset of the disease, P less than 0.05. But only TLR 2, 3, 8 mRNA levels remained increased in patients within 7 or 14 days since onset (P less than 0.05). Mean levels of mRNA for TLR 4 in PBMC was higher in patients with more severe diarrhea including longer duration of diarrhea, more episodes of diarrhea per day and higher severity scores (P less than 0.05).</p><p><b>CONCLUSION</b>Manifold TLR may play roles in the start-up and regulation of immune responses in children with acute rotavirus diarrhea. These findings will be helpful to further recognize immune response in Chinese children with rotavirus diarrhea and, consequently, may provide directions and insights that could prove critical to the prevention or treatment of this important disease.</p>