Platelets express a membrane protein complex immunologically related to the fibroblast fibronectin receptor and distinct from GPIIb/IIIa

We have previously identified and characterized a membrane glycoprotein complex (GP150/135) that functions as fibronectin receptor (FN-R) in fibroblast adhesion. Here we report that an immunologically related protein complex is expressed at the surface of human platelets. Antibodies monospecific for the smaller subunit (GP135) of the fibroblast FN-R in fact specifically stained the platelet surface, as determined by FACS analysis, and reacted with a component of molecular weight (mol wt) 138,000 as shown in western blots of platelet membranes. Moreover, the same antibodies precipitated the 138,000 component together with a 160,000 protein, suggesting that the two molecules are associated in a supramolecular complex. A comparative analysis indicated that this protein complex is distinct from the GPIIb/IIIa complex, known to function as a receptor of wide specificity for fibrinogen, fibronectin, and von Willebrand factor. Differential extraction experiments revealed that the platelet 138,000 component is an integral membrane protein.     

维生素C及E联合作用对体外大鼠胚胎中脑神经细胞分化和增殖的影响

目的:观察维生素C,维生素E和维生素C 维生素E联合后对胚胎中脑神经细胞生长发育的影响。方法:实验于2006-03/04在江苏大学医学院研究中心细胞培养室完成。采用16d大鼠胚胎中脑神经细胞体外培养方法,观察不同剂量的维生素C(5,10,25,50μmol/L),维生素E(10,25,50,100μmol/L)和维生素C、维生素E联合作用(维生素C25μmol/L 维生素E50μmol/L,维生素C50μmol/L 维生素E100μmol/L),培养10d后收集细胞,并利用图像分析细胞形态的变化、蛋白质、丙二醛含量及超氧化物歧化酶活性指标。结果:①维生素C、维生素E和维生素C 维生素E联合能促进体外培养中脑神经细胞突起生长,集落数增多。②与正常对照组比较,维生素C10,25μmol/L组、维生素E10,25,50μmol/L组、维生素C25μmol/L 维生素E50μmol/L组神经细胞总蛋白相对含量明显增加。③与正常对照组比较,维生素C10,25μmol/L组、维生素E25,50μmol/L组、维生素C25μmol/L 维生素E50μmol/L组神经细胞超氧化物酶活性增加,丙二醛含量降低。④维生素C50μmol/L组、维生素E100μmol/L组和维生素C50μmol/L 维生素E100μmol/L组超氧化物酶活性低于正常对照组,丙二醛含量高于正常对照组。结论:维生素C、维生素E和维生素C 维生素E联合剂量在一定范围内能够明显提高中脑神经细胞的抗氧化能力,同时能促进胚胎中脑神经细胞分化和增殖作用。     

心脏主动脉双叶瓣流固耦合模型定常流场数值的分析

目的:人工心脏瓣膜置换术后的并发症均与心瓣膜置换后引起的血流特性紊乱有关,因此分析心脏主动脉位置双叶人工机械心瓣/血液耦合系统的血流动力学特性和瓣叶机械应力分布情况,为机械心瓣的设计、优化和临床研究提供一定理论依据。方法:采用大型有限元分析软件ANSYS中的CFD(计算流体动力学)模块并运用顺序耦合分析方法分别建立物理环境和结构环境对双叶人工机械心脏瓣膜与其周围血液进行单向流固耦合分析。结果:获得了瓣膜在稳态流动情况下合理的血流速度场、压力场和流体切应力的分布情况及瓣阀的机械应力分布图。在减速时相下,人工机械瓣的速度场出现明显的湍流区、回流区及漩涡区;跨瓣压差较小,压力场有低压力分布;最大雷诺切应力出现在瓣叶窄流道附近,下游壁面附近有低切应力(雷诺切应力)分布,且峰值切应力远离壁面;人工机械瓣叶上无应力集中现象产生。结论:采用大型有限元分析软件ANSYS,建立了主动脉机械双叶瓣-血液耦合运动的两维数值模型,初步采用CFD中的顺序耦合分析方法对血液通过主动脉位置的人工机械瓣进行了单向流固耦合分析的方法是可行的。     

Duration of time from onset of human immunodeficiency virus type 1 infectiousness to development of detectable antibody. The HIV Seroconversion Study Group

Background : For persons newly infected with the human immunodeficiency virus type 1 (HIV-1), the time from the onset of infectivity to the development of detectable HIV-1 antibody is unknown. Persons who donate blood during this period account for nearly all instances of HIV-1 transmission from HIV-1 antibody-screened blood transfusions. Study Design and Methods : To estimate the window period from infectivity to HIV-1 antibody positivity, 701 HIV-1-seropositive blood donors who made a previous seronegative donation at 40 United States blood centers were studied. The HIV-1 antibody status was determined for at least one recipient of blood from the seronegative donation preceding the seropositive donation made by 182 of the 701 donors. Results : There were 39 seropositive recipients of blood from these 182 donors. Three donors were excluded from further analysis because the seropositive recipients of their blood had other HIV-1 risk factors or had HIV-1 infection before transfusion. The final study population comprised the remaining 179 donors, of whom 36 (20%) transmitted HIV-1 infection to recipients. When the interval between the seropositive donation and the preceding seronegative donation was less than 180 days, 46 percent of the donors transmitted HIV-1. In contrast, when that interval exceeded 540 days, only 2 percent transmitted HIV-1. A mathematical model was developed to explain the relationship between the probability that the previous seronegative donation occurred during the donor's window period of infectiousness, and hence transmitted HIV-1, as a function of both the window period and the duration between the seropositive and previous seronegative donations. This model indicated that the transmission data were most consistent with an average window period of 45 days. Assuming a log-normal window period distribution, it was estimated with 95 percent certainty that at least 90 percent of persons had a window period of less than 141 days. Conclusion : The window period averages 45 days, with few, if any, donors remaining infectious and seronegative for longer than 6 months.