Effects of Tcd A on Rho GTPases and the Cytoskeleton of Leukemia Cell Line K562 / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the effect of clostridium difficile toxin A(TcdA) on the Rho GTPases and the cytoskeleton in K562 cells.</p><p><b>METHODS</b>K562 cells were cultured in vitro with different concentration of TcdA.The effect of TcdA proliferation of cells was detected by MTT method after the K562 cells were stimulated with TcdA for 24,48 and 72h; the expression of cdc42, RhoA, Rac1 mRNA was assessed by RT-PCR; the changes of the microtubule, the microfilament were observed by confocal laser scanning microscopy.</p><p><b>RESULTS</b>The proliferation of K562 cells was inhibited after exposure to TcdA for 24, 48 and 72h, and the inhibitory rate was 47.67% in the treatment for 48 h. the cdc42，RhoA and Rac1 mRNA expressions in the experimental groups decreased after treated with TcdA(P<0.05), which positively correlated with concentration of TcdA. Also, the microfilament decreased ,which was observed by confocal laser scanning microscopy.</p><p><b>CONCLUSION</b>TcdA inhibites K562 cell proliferation and induces apoptosis, TcdA can change the cytoskeleton structure through the cytoskeletal protein genes cdc42 and RhoA, Rac1 mRNA expression,. It is related with cell microfilament content decreasing.</p>

Study of dental caries and correlated factors of 12-year-old children in Dongxiang, Baoan and Yugu races / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the epidemiology of dental caries and its correlated factors of 12-year-old children in Dongxiang, Baoan and Yugu races.</p><p><b>METHODS</b>According to the method of third national oral health epidemiologic investigation, 448 12-year-old children in Dongxiang, Baoan and Yugu races were randomly collected and the epidemiological investigation of dental caries, oral bacteriological detection and oral hygiene behavior were carried out.</p><p><b>RESULTS</b>1) The caries prevalence rate of Dongxiang, Baoan and Yugu races were 40.52%, 44.29%, 46.45%, respectively. The average caries of Dongxiang, Baoan and Yugu races were 0.92, 0.90, 1.13, respectively. 2) The main ranks of Streptococcus mutans in saliva were class 2 and class 3 in Dongxiang and Baoan races. However, it was class 0 or class 1 in Yugu race. The level of Streptococcus mutans in dental plaque was higher in Dongxiang and Baoan races than in Yugu race. 3) The children's everyday brushing rate was higher in Yugu race than in Dongxiang and Baoan races (P<0.01). But there were no difference between Dongxiang and Baoan races.</p><p><b>CONCLUSION</b>The caries prevalence rates of 12-year-old children in Dongxiang, Baoan and Yugu races are high. The main factors of high caries prevalence rate were low brushing rate and dental plaque couldn't be removed effectively. Oral health education should be strengthened in the three race areas.</p>

An overview of type E botulism in China / 生物医学与环境科学（英文）

The geographical distribution of C. botulinum type E and its associated disease, type E botulism in China, is different from that in other areas of the world. Cases of type E botulism generally arise in costal regions. In China, however, type E botulism is found primarily in the Qinghai-Tibet plateau of northwest China far from the ocean, at an altitude of approximately 4-5 km. The foods most commonly associated with the disease are fermented grain and beans as well as raw meat. A suspected outbreak of type E botulism poisoning in the central costal region of China in the 1990s prompted the collection and analysis of samples of mud, sand, and fish from the region. The toxin produced by type E botulinum was found in these samples. Surprisingly, though, upon further analysis, the strain isolated from the samples was identified not as type E C. botulinum, but as the neurotoxigenic bacterium Clostridium butyricum.