The structure and function of platelet-activating factor acetylhydrolases

Platelet-activating factor acetylhydrolases (PAF-AHs, EC 3.1.1.47) constitute a unique and biologically important family of phospholipase A2s. They are related to neither the well-characterized secretory nor cytosolic PLA2s, and unlike them do not require Ca2+ for catalytic activity. The distinguishing property of PAF-AHs is their unique substrate specificity: they act on the phospholipid platelet-activating factor (PAF), and in some cases on proinflammatory polar phospholipids, from which they remove a short acyl moiety--acetyl in the case of PAF--located at the sn-2 position. Because PAF is found both in the plasma and in the cytosol of many tissues, PAF-acetylhydrolases are equally widely distributed in an animal organism. Recent crystallographic studies shed new light on the complex structure-function relationships in PAF-AHs.     

The treatment influence on the electric strength and conductivity of fibroin

The influence of thermal treatment and liquid nitrogen treatment of cocoons on the electric properties of natural silk fibroin has been studied. It is found that, at the cocoon treatment by liquid nitrogen, the ratio of the amorphous and crystalline parts of the fibroin is preserved and the concentration of submicrocracks in them changes to a lesser extent than at treatment by heated air and a UHF field. The increase of the degree of crystallinity in the polymers leads to a certain increase of their breakdown voltage.     

有限精度时间自动机的可达性检测

为了缓解状态空间爆炸问题,减小模型检测过程中生成的状态空间,加快模型检测速度,引入有限精度时间自动机(finite precision timed automata,简称FPTA)作为实时系统的形式模型,并提出了一种数据结构SDS(series of delay sequence)符号化表示状态空间中的状态集.FPTA只记录时钟变量的整数值及时钟变化的先后次序,从而减小生成的状态空间.在一定的时间约束下,Alur与Dill提出的时间自动机的可达性检测可简化为FPTA的可达性检测.举例描述了状态空间的生成过程和表示方法.最后,列出部分初步的实验结果,分析了SDS的特点及不足.     

Dyslipidemias and autoimmune diseases

The paper summarizes the results of over 30-year studies dealt with dyslipidemias and autoimmune diseases. The teaching of the antiphospholipid syndrome (APS) has aroused interest in the problem. The experience gained shows changes in the blood cholesterol transport system. Patients with systemic lupus erythematosus (SLE) have higher levels of low density lipoprotein cholesterol and lower concentrations of high density lipoprotein (HDL) cholesterol, apolipoprotein A than the controls. The quantitative and qualitative changes in particles result in decreased acceptance of cholesterol from the membrane of a cell and tissues, which promotes the development of vascular diseases. Lipoprotein (a) may be an additional risk factor for thrombosis chiefly of coronary arteries, in patients with SLE and APS. Increased levels of oxidized low density proteins having atherogenic activity were found mainly in patients with SLE. The use of corticosteroids causes the changes in the spectrum of blood lipids, which together with other factors (thrombosis, vasculopathy, thrombocytopenia, etc.) create good conditions for the development of atherosclerosis, which determines the necessity of correcting the parameters of blood lipid transport not only to prevent vascular disorders but to improve the general life prognosis in SLE patients.