Inhibition of M-MuLV reverse transcriptase activity by fullerene derivatives

The biological properties and biomedical application of fullerene (C60) and its derivatives are currently very active subjects concerning fullerene research. The bio logical effects of fullerene and its derivatives include enzyme inhibition, sites-selective DNA cleavage, antibacterial and antiviral activities, photocytotoxicity and antiapoptosis[1―4]. Especially, enzymes inhibited by fullerene derivatives mainly consist of oxidation-reduc- tion related enzymes such as glutathione transferase…     

Delphi中自动化对象的动态绑定

OLEAutomation是Windows应用程序之间相互通信的一种技术.Automation服务器分为3种In-Process服务器、Out-of-Process服务器、Remote服务器.AutomationObject属于In-Process服务器(进程内服务器),它以COM的形式提供组件服务,通过动态绑定技术实现功能资源(DLL或COM)的动态调用.     

软件动态度量及其在逆向工程中的应用

在对软件度量进行分析的基础上,指出常用的软件度量是静态的,只反映了系统可能的属性,而不是实在属性.定义了动态扇入扇出度量,用实例说明它们不但反映了系统实在的的属性,还可以用于确定系统中的关键组件,推断系统的功能.基于这个特性,提出了一种在逆向工程中快速认定系统中某一功能的具体实现过程的方法.在这种方法中使用了标有动态扇入扇出值的程序依赖图和部分植入技术.运用这种方法得到的信息量较少但都是与用户的关注点密切相关的,有助于用户快速理解系统.     

图的循环定向

Barot,Geiss和Zelevingsky曾经给出了一个图是否可定向的判断方法.该方法对图中所有圈上的边依次排序编号,然后考察不同的圈是否有不同的极大边,或者是计算顶点、边、圈和连通分支间的数量关系.本文给出另外一种判定方法.该方法主要通过观察顶点之间的链进行.     

图的循环定向

M.Barot,C.Geiss和A.Zelevinsky曾经给出了一个图是否可定向的判断 方法.该方法对图中所有圈上的边依次排序编号，然后考察不同的圈是否有不同 的极大边，或者是计算顶点、边、圈和连通分支间的数量关系.本文给出另外一 种判定方法，我们的方法主要是通过观察顶点之间的链进行.     

新疆HIV传播的动力学分析与模拟

通过对HIV病毒传播机理的分析,利用动力学方法建立HIV传播的动力学模型,分析影响疾病传播和控制的关键因素.通过模型分析得到了决定疾病传播与否的基本再生数R0,证明了R01时疾病将会消除,R01时疾病将变成一种地方病.用收集和估计的参数对模型进行了数值模拟,分析新疆HIV的流行状况,给出了模型参数的敏感性分析.     

HIV感染者血浆病毒载量的动态分析

目的：探索HIV感染者血浆病毒载量的变化规律。方法：用EDTA试管采集血液,分离血浆,通过RT-PCR检测血浆病毒载量。结果：0个月3、个月、6个月和9个月检测的病毒载量,杨某分别为1.698×106c/ml、1.123×106c/ml、1.037×106c/ml和1.239×106c/ml,丁某相应时间的病毒载量分别是1.013×106c/ml、7.312×105c/ml、6.676×105c/ml和6.063×105c/ml,李某相应时间的病毒载量分别是1.778×105c/ml1、.023×105c/ml、1.333×105c/ml和1.256×105c/ml。结论：不同HIV感染者血浆病毒载量不同,其变化规律也存在差异。     

Coffee contains potent opiate receptor binding activity

Opiate receptor-active peptide fragments (exorphins) have been identified recently in casein and gluten hydrolysates, and morphine has been found in bovine and human milk. To determine whether similar peptides or alkaloids occur in other foodstuffs, we have screened potential sources using a rat brain homogenate assay to detect opiate receptor activity. We report here that instant coffee powders from a variety of manufacturers compete with tritiated naloxone for binding to opiate receptors in the rat brain membrane preparations, with no significant difference between normal and decaffeinated coffee. The receptor binding activity resembles that seen with opiate antagonists, in that there was no change in the half-maximal effective dose (ED50) in the presence of 100 mM Na+; on bioassay, the activity was similarly shown to be antagonistic and specific for opiate-induced inhibition of twitch. Preliminary characterization of the activity reveals that it has a molecular weight (MW) in the range 1,000-3,500, is heat-stable, ether-extractable, not modified by enzymatic digestion with papain, and clearly separable from caffeine and morphine on TLC. As its concentration in an average cup of coffee is five times the ED50, these data suggest that drinking coffee may be followed by effects mediated via opiate receptors, as well as effects of caffeine.     

HIV传播人群生态动力学模型的匹配解

利用奇摄动方法研究一类HIV传播的动力学模型, 先构造模型解的外部解和内层解, 再进行匹配, 得到了模型解的合成展开式, 并对解进行了精度比较, 证实了渐近展开式具有较高的精度. 结果表明, 得到的近似解可以描述流行性传染病区域的人群传播规律.     

Single amino-acid changes in HIV envelope affect viral tropism and receptor binding

Infection by the human immunodeficiency virus (HIV) is initiated by the binding of its extracellular envelope glycoprotein, gp120, to the CD4 antigen on target cells. To map the residues of the HIV-1 glycoprotein that are critical for binding and to analyse the effects of binding on viral infectivity, we created 15 mutations in a region of gp120 that is important for binding to CD4 (refs 4,5). We find that substitution of a single amino acid (tryptophan at position 432) can abrogate CD4 binding and that virus carrying this mutation is non-infectious. By contrast, other amino-acid changes in the same region do not affect CD4 binding but restrict viral tropism: virions containing isoleucine substitutions at position 425 lose their ability to infect a monocyte cell line (U937 cells) but can still infect T-lymphocyte cell lines (CEM, SUP-T1) and activated human peripheral blood lymphocytes. These results indicate that cellular tropism of HIV can be influenced by a single amino-acid change in gp120.