Pathogenicity islands and phage conversion: evolutionary aspects of bacterial pathogenesis

Horizontal gene transfer plays a key role in the generation of novel bacterial pathogens. Besides plasmids and bacteriophages, large genomic regions termed pathogenicity islands (PAIs) can be transferred horizontally. All three mechanisms for DNA exchange or transfer may be important for the evolution of bacterial pathogens.     

Aberrant DNA methylation of the p16INK4a gene in plasma DNA of breast cancer patients.

Hypermethylation of exon 1 of p16INK4a was examined in tumour and plasma DNA of a series of breast cancer patients. De novo methylation was observed in the tumours of eight patients (23%), and in plasma DNA in five (14%) of these eight patients. Our data show that de novo methylation of exon 1 of p16INK4a can be demonstrated in plasma DNA of breast cancer patients, a fact that provides additional evidence of the tumour-related origin of free plasma DNA in cancer patients.     

Detection and analysis of “CpG-rich” islands in the genome of Physarum polycephalum

Summary A small fraction (Physarum polycephalum contains a high-density of cleavage sites for the restriction endonuclease HpaII. This component can be distinguished from the bulk of the DNA by ³²P-end-labelling followed by size-fractionation using agarose-gel or polyacrylamide-gel electrophoresis. In contrast to the situation in mammalian-cell DNA, where the majority of such small HpaII DNA fragments are derived from CpG-rich islands within diverse single-copy sequences located in the proximity of housekeeping genes, most of the Physarum small HpaII DNA fragments form an array of distinct bands when analysed on polyacrylamide gels, indicating that they are repetitive DNA sequences. Direct sequence analysis shows that the majority of these sequences are derived from the Physarum rDNA minichromosome.     

Effects of 2,5-hexanedione on angiogenesis and vasculogenesis in chick embryos

n-Hexane is widely used in industry and its metabolite, 2,5-hexanedione (2,5-HD), has been implicated as a neural toxin in the developing fetus. Using the chick embryo model, we have previously revealed the neurotoxicity of 2,5-HD during development and established that high dose of 2,5-HD was embryo lethal. In view of the close linkage in biology for neurogenesis and angiogenesis, we speculated that it was most likely caused by cardiovascular dysplasia, therefore in this study, we investigated the effects of 2,5-HD on the development of the vasculature, which involves vasculogenesis and angiogenesis. Using gastrulating chick embryos as a model, we demonstrated that the hemangioblasts (precursor of hematopoietic and endothelial cells) migrated to the area opaca where they form the blood islands. However, this process was impaired when the embryos were treated with 2,5-HD, suggesting that 2,5-HD is capable of impairing vasculogenesis. To study the effect of 2,5-HD exposure on angiogenesis, we used the chick yolk-sac membrane (YSM) and chorioallantoic membrane (CAM) models. We found that, at low (0.02 M) concentration, 2,5-HD stimulated angiogenesis while at higher concentrations (>0.1 M) it inhibited this process. This biphasic response of angiogenesis to 2,5-HD exposure was found to be associated with altered expression of the VEGF-R, FGF-2 and angiogenin. Moreover, we also determined that 2,5-HD exposure increased the reactive oxygen species (ROS) production. In conclusion, 2,5-HD could induce dysplasia in the developing vasculature, which in turn could cause extravascular hemolysis and the embryos to die.     

中医辨证点穴法对2型糖尿病患者血糖和胰岛功能作用的临床研究

[目的]观察中医辨证点穴法对2型糖尿病患者血糖及胰岛功能的临床效果。[方法]选择符合入选标准的160例2型糖尿病患者,按病程长短进行分层分为初发组、1~3 a组,3~5 a组,每层随机分为治疗组及对照组,对照组采用常规降糖治疗,治疗组在此基础上加用中医辨证点穴方法治疗,治疗2周后比较两组血糖、症状积分、HOMA指数、胰岛第1时相功能、胰岛第2时相功能。[结果]治疗组总有效率优于对照组,P0.05,在血糖控制、症状改善上均优于对照组(P0.05),稳态评估模型(HOMA)指数、胰岛第1时相功能明显高于对照组(P0.01或0.05)具有统计学差异。[结论]中医辨证点穴方法能有效改善2型糖尿病患者症状、有效控制血糖,对胰岛功能亦有一定恢复作用,有推广应用价值,需进一步深入研究。     

表观遗传学和环境因素与子宫内膜异位症

子宫内膜异位症(EMs)是一种雌激素依赖的炎性疾病,发病机制尚不清楚。越来越多的证据表明,一些基因的表观遗传学特性与EMs的发病有关。表观遗传学是指DNA序列不发生变化,但基因表达却发生了可遗传的改变,包括DNA甲基化、组蛋白共价修饰及染色质构象变化,这些改变可能会引发一系列包括肿瘤在内的病理变化。EMs异位组织中芳香化酶基因的Cp G岛序列低甲基化和(或)反式作用因子上调芳香化酶基因的表达;卵巢异位上皮及间质细胞的雌激素受体α(ERα)低表达而ERβ显著高表达;在位细胞的孕激素受体α(PRα)和PRβ均高表达;EMs异位内膜细胞的类固醇生成因子1(SF-1)启动子低甲基化而在位内膜高甲基化。此外,EMs异位组织E-钙黏蛋白(E-cadherin)基因及在位组织同源框基因A10(HOXA10)表达降低也与EMs有关;环境因素可能会影响表观遗传基因导致EMs的发生。综述表观遗传学改变和环境因素在EMs发病中的作用。     

中国南海重要岛屿恙虫病疫源地特点调查

目的研究比较南海重要岛屿（南澎列岛、南澳岛、万山群岛、硇洲岛、雷卅半岛）恙虫病疫源地特点。方法在各岛进行恙虫病疫源地流行病学调查、病原分离与基因型鉴定并制定预防措施。结果南海诸岛屿均为恙虫病南亚热带岛屿疫源地，主要宿主为褐家鼠，恙虫病东方体携带率为22．78％～33．75％。主要媒介为地里纤恙螨，恙虫病东方体携带率为40．00％～75．00％。从宿主与媒介分离到恙虫病东方体25株，经基因鉴定Karp15株、Kato8株、Yonchon2株。血清流行病学调查表明，各个岛屿村民与驻岛部队人群恙虫病抗体阳性率均较高。结论南海岛屿恙虫病疫源地存在一定特点，尤其是外来人群要做好防护。[第一段]     

HISTOPATHOLOGIE DE LA MOELLE DANS LE SYNDROME MYELODYSPLASTIQUE

62 cases of myelodysplastic syndrome have been examined histopathologically There were 30 males and 32females with ages from 20 months to 74 years old. 31 cases (50%) showed erythroblastic islands, 51 cases (82.2%) abnormal localization of immature precursors (ALIP) and 39 cases (62.9%) micromegakaryocytes. ALIP was present in 41/45 of cases with lencocytosis. Only 16.1% of the cases presented the coexistences of the 3 typical histopathological changes while 100% of the cases showed 2 of the three changes. The correlation of the clinical and the histopathological diagnosis was 76%. Differential diagnosis were discussed.     

High number of striatal dopaminergic neurons during early postnatal development: correlation analysis with dopaminergic fibers

Dopamine (DA) axons in the developing striatum cluster in discrete areas called "DA islands". During the third postnatal week, most DA islands are no-longer detectable and the DA innervation becomes uniform. In this study we explored the relationship between the pattern of DA innervation and the number of striatal tyrosine hydroxylase positive (TH+) cells during early postnatal development. By using dedicated stereology we found that the newborn striatum contains striatal TH+ cells, which cluster around newly sprouted DA axons. The number of these cells decreases when DA axons develop a full pattern of striatal innervation. This condition suggests a causal relationship between the amount of striatal DA innervation and the presence of striatal DA neurons. A better knowledge of the mechanisms regulating the ontogenesis of the nigrostriatal DA system may pave the way to strategies of neurorescue of the DA system.