Micronucleus test in mussels Perna perna fed with the toxic dinoflagellate Prorocentrum lima

Micronucleus (MN) and other nuclear abnormalities have been measured in the hemocytes of mussels Perna perna to verify whether feeding mussels with different concentrations of Prorocentrum lima results in accumulation of levels of okadaic acid (OA) capable of inducing genotoxic effects at the chromosome level, as evidenced by micronuclei and nuclear abnormalities. Four groups of 12 mussels housed individually in aquaria containing filtered seawater were fed with different concentrations of P. lima. Another group collected directly from the production area served as outdoor control. A significantly higher frequency of MN and nuclear lesions was observed in hemocytes from the groups fed P. lima.     

Iron stimulates the rate of reduction of hexavalent chromium by human microsomes

The NADPH-dependent reduction of chromium (VI), a known carcinogen, by hepatic microsomes was very similar for all five humans examined, with an apparent Km for chromate of 1.04-1.68 microM, and a Vmax of 10.4- 10.7 nmol/min/mg protein. Inhibitor studies indicate no role for cytochrome P450s, but a prominent role for flavoproteins, which could include P450 reductase, flavin-containing mono-oxygenase and cytochrome b5. Relative to anaerobic conditions, Cr(VI) reduction was inhibited only 26-37% by room air, which indicates that human microsomal Cr(VI) reduction could still proceed at significant rates, even in tissues with high O2 tensions. Studies with lung microsomes from one human exhibited Vmax and Km values that were two-thirds lower and 2.8-fold greater, respectively, than those of hepatic microsomes from the same individual; other Cr(VI)-reducing parameters were similar for lung and liver. Various forms of exogenous iron, when present at 0.76-6.3 microM, markedly enhanced both liver and lung microsomal rates and Vmax of Cr(VI) reduction, but did not significantly alter the other Cr(VI)- reducing parameters (Km, effects of O2 and inhibitors). These iron levels were 3.1- to 26-fold lower than the initial Cr(VI) concentration, which suggests that iron is serving a catalytic role. The ratio of human microsomal Cr(VI) reduction rates under aerobic versus anaerobic conditions remained fairly constant, regardless of iron concentration. Small increases in intracellular iron could therefore lead to large increases in the rate and extent of microsomal Cr(VI) reduction. Individuals that are simultaneously exposed to Cr(VI) and to agents that increase intracellular iron could therefore be at potentially greater risk for Cr(VI) toxicity and carcinogenicity.      

小鼠Nanog基因的克隆及对人宫颈癌上皮细胞的作用

目的:克隆小鼠Nanog基因并构建带绿色荧光蛋白的真核表达载体pG-Nanog,观察其对人宫颈癌上皮细胞(Hela细胞)中的表达,旨在为进一步观察其对成体细胞的表型变化及细胞增殖奠定前期实验学基础。方法:实验于2006-03/09在西北农林科技大学陕西省干细胞研究中心完成。Nanog基因的克隆参照庄淑珍的方法。Nanog基因真核表达载体的构建参照GeneBank中的小鼠Nanog基因序列,以pNA992为模板扩增Nanog基因,PCR产物以BglⅡ和SacⅡ双酶切,同时将pEGFP-C1用BglⅡ和SacⅡ鉴定,将该质粒命名为pG-Nanog。Hela细胞用含10%新生牛血清的Dulbecco’s改良培养基(Dulbecco’sModifiedEagleMedium,DMEM)培养,转染Hela细胞。转染前1d,在6孔板的每个孔中接种1.2×105个细胞,待细胞生长至60%～70%汇合时,取pG-Nanog与空载体各4μg分别加入500μL无血清无抗生素的DMEM培养液中,同时将6μL稀释于500μL无血清无抗生素的DMEM(干粉)培养液中,将两者混合,室温静置20min,将复合物加入到细胞中,置37℃,体积分数0.05的CO2培养箱中转染24h后吸出复合物加入完全培养基,48h后观察荧光。合成内源对照β-actin,收集转染4d后的细胞提取RNA,反转录为cDNA,然后分别扩增Nanog基因和β-actin基因。采用RT-PCR的方法检测Hela细胞中Nanog基因的表达。结果:①pEGFP-C1载体经双酶切后获得约1kbp的Nanog基因真核表达载体片段,同预期结果相一致,测序结果同GeneBank中的序列同源性达到99.7%。②将转染48h后的Hela细胞置于荧光显微镜下观察,可见明显的荧光,转染pG-Nanog的细胞绿色荧光蛋白集中于细胞核,将转染4d后Hela细胞的总RNA进行RT-PCR检测,产物经琼脂糖电泳分析,只有转染pG-Nanog的细胞中才能够检测到Nanog基因的相应条带。③转染48h后,对细胞进行抗增殖细胞核抗原免疫组化染色,未转染细胞和转染空质粒细胞及转染pG-Nanog细胞染色结果均呈阳性,转染了pG-Nanog的Hela细胞与正常细胞和转染空载体的细胞相比细胞形态发生了一定的改变,细胞表面形成了许多突起。结论:小鼠Nanog基因的克隆、真核表达载体的构建及在Hela细胞中的表达均获得成功,并观察到Hela细胞发生了形态的改变。     

Review of the Lynch syndrome: history, molecular genetics, screening, differential diagnosis, and medicolegal ramifications

Platelets have a central role in the development of arterial thrombosis and subsequent cardiovascular events. An appreciation of this complex process has made antiplatelet therapy the cornerstone of cardiovascular disease management. However, numerous patients will experience a recurrent atherothrombotic vascular event despite adequate antiplatelet therapy. Individual differences in the rate of platelet activation and reactivity markedly influence normal hemostasis and the pathological outcome of thrombosis. Such an individual variability is largely determined by environmental and genetic factors. These are known to either hamper platelets' response to agonists, and thereby mimic the pharmacological modulation of platelet function or mask therapy effect and sensitize platelets. In this article, we reviewed the antiplatelet mechanisms of aspirin and clopidogrel and the possible role of different polymorphisms, which may affect the efficacy of antiplatelet therapy. Heterogeneity in the way patients respond to aspirin and clopidogrel may in part reflect variation in cyclooxygenase (COX)-1, COX-2, glycoprotein (GP) Ib alpha, GP Ia/IIa, GP IIb/IIIa, UGT1A6*2, P2Y₁, P2Y₁₂, CYP2C9, CYP3A4 and CYP3A5 genotypes.     

Effects of the temperature, the duration of frozen storage, and the freezing container on in vitro measurements in human peripheral blood mononuclear cells

Background: Bone marrow, peripheral blood, and umbilical cord blood have been used to prepare autologous and allogeneic pluripotential mononuclear cells for use in the repopulation of bone marrow. Study Design and Methods: The purpose of this study was to evaluate how the temperature and duration of frozen storage of human peripheral blood mononuclear cells (PBMCs), as well as the freezing container, affected the in vitro recovery and viability of the mononuclear cells and their growth in colony-forming unit-granulocytic-erythroid-monocytic- megakaryocytic (CFU-GEMM) tissue culture assay. PBMCs were isolated from ficoll-hypaque-treated cellular residue obtained during the plateletpheresis of blood from 15 healthy donors. The PBMCs were treated with dimethyl sulfoxide (DMSO) to achieve a final DMSO concentration of 10 percent. Each unit was then separated into six aliquots: one stored in a polyvinylchloride (PVC) plastic bag, one in a polyolefin plastic bag, and four in polyethylene cryostorage vials. Each aliquot was frozen in a -80 degrees C mechanical freezer at a freezing rate of 2 to 4 degrees C per minute. The frozen PBMCs in PVC bags were stored in a -80 degrees C mechanical freezer and those in polyolefin bags in a -135 degrees C mechanical freezer. Each of the four frozen samples in a vial was stored at a different temperature: one in the -80 degrees C freezer, one in the -135 degrees C freezer, one in the vapor phase of liquid nitrogen at -150 degrees C, and one in liquid nitrogen at -197 degrees C. Some of the frozen PBMCs were stored for periods of 1 to 1.5 years and others for 2 to 2.4 years, after which they were thawed, washed, and tested. Results: The samples stored in PVC bags and those stored in polyolefin bags exhibited in vitro recoveries that were 90 percent of the recovery of fresh PBMCs and viabilities of 90 percent after 2.4 years of frozen storage. The PBMCs stored in PVC bags exhibited no loss of CFU-GEMM activity after 1 to 1.5 years, but a 40-percent loss of activity was observed after 2 to 2.4 years. PBMCs stored in polyolefin bags, however, exhibited no loss of CFU-GEMM activity, even after 2 to 2.4 years of storage. In vitro recovery was significantly lower in PBMCs stored in vials at -80 degrees C or -135 degrees C than in cells stored in PVC or polyolefin bags at these temperatures, both in the 1- to 1.5-year and the 2- to 2.4-year time frames. In vitro recovery and viability were similar in PBMCs stored in vials at -80 degrees C, -135 degrees C, -150 degrees C, and -197 degrees C. The growth patterns in the CFU-GEMM assay in PBMCs stored in vials were significantly lower after storage at -80 degrees C than after storage at -135 degrees C, -150 degrees C, or -197 degrees C. Conclusion: PBMCs isolated by leukapheresis and ficoll-hypaque treatment can be frozen with 10-percent DMSO in a -80 degrees C mechanical freezer. When a PVC bag is used for freezing and storage of PBMCs at -80 degrees C, the duration of frozen storage should not exceed 1.5 years, whereas PBMCs frozen in a polyolefin bag can be stored in a -135 degrees C freezer for as long as 2.4 years. When these guidelines were followed, in vitro recovery was 90 percent that of fresh PBMCs, viability was 90 percent, and growth in the CFU-GEMM tissue culture assay was similar to that of fresh PBMCs. The PBMCs frozen and stored in PVC or polyolefin bags exhibited satisfactory results, whereas those stored in cryostorage vials did not.     

1型糖尿病研究新进展

40年前创立的青少年糖尿病研究基金会((JDRF)是一个致力于通过支持研究来探寻1型糖尿病(TIDM)及其并发症治疗方法的组织.20世纪70年代有学者提出,TIDM和2型糖尿病(T2DM)的发病机制有根本的不同,T1DM与主要组织相容性复合体的人白细胞抗原(HLA)有独特相关性,有胰岛细胞自身抗体.