聚合酶β在肝癌细胞DNA辐射损伤修复中的作用

利用第二军医大学裸鼠移植性肝癌细胞（ＳＭＭＣ－ＬＴＮＭ）和不同的ＤＮＡ聚合酶选择性抑制剂ＮＥＭ与ｄ２ＴＴＰ，探讨了肿瘤细胞核中ＤＮＡ聚合酶β参与γ射线辐射损伤ＤＮＡ修复的作用特点，结果表明，该酶参与真核细胞γ射线辐照损伤的ＤＮＡ修复合成，是一种重要的ＤＮＡ修复酶，与正常肝细胞相比，ＳＭＭＣ－ＬＴＮＭ肝癌细胞ＤＮＡ聚合酶β的ＤＮＡ修复合成反应速度快，修复能力强，提示某些肿瘤细胞中该酶的ＤＮＡ辐射损伤     

基于SDH不中断业务链最优化成环的研究及应用

文章根据宜昌光通信网现状结构分析研究进行优化设计和整改,实现不中断业务平台的接入,把通信网的链路整改成环网,完成环网上的断纤保护,实现自愈环功能,便于维护管理形成安全稳定可靠的通信网。     

稀土材料新进展

叙述了稀土材料的新种类以及应用前景，并对国内稀土工业的现状及其存在的问题、国外稀土市场概况进行了综述，同时，展望了我国稀土材料的发展方向。     

Study on Compound Effect of Bonded Magnets

The compound effect of Nd2Fe14B/Fe3B-Ferrite bonded magnets was studied.The result shows that the value ofβjHC obviously decreases with the ferrite content increasing.In addition, a functional relation between magnetic properties and ferrite content was clearly revealed by the physical relation in the magnetic powders.     

Role of ERAB/L-3-hydroxyacyl-coenzyme A dehydrogenase type II activity in Abeta-induced cytotoxicity

Endoplasmic reticulum-associated amyloid beta-peptide (Abeta)-binding protein (ERAB)/L-3-hydroxyacyl-CoA dehydrogenase type II (HADH II) is expressed at high levels in Alzheimer's disease (AD)-affected brain, binds Abeta, and contributes to Abeta-induced cytotoxicity. Purified recombinant ERAB/HADH II catalyzed the NADH-dependent reduction of S-acetoacetyl-CoA with a Km of approximately 68 microM and a Vmax of approximately 430 micromol/min/mg. The contribution of ERAB/HADH II enzymatic activity to Abeta-mediated cellular dysfunction was studied by site-directed mutagenesis in the catalytic domain (Y168G/K172G). Although COS cells cotransfected to overexpress wild-type ERAB/HADH II and variant beta-amyloid precursor protein (betaAPP(V717G)) showed DNA fragmentation, cotransfection with Y168G/K172G-altered ERAB and betaAPP(V717G) was without effect. We thus asked whether the enzyme might recognize alcohol substrates of which the aldehyde products could be cytotoxic; ERAB/HADH II catalyzed oxidation of a variety of simple alcohols (C2-C10) to their respective aldehydes in the presence of NAD+ and NAD-dependent oxidation of 17beta-estradiol. Addition of micromolar levels of synthetic Abeta(1-40) to purified ERAB/HADH II inhibited, in parallel, reduction of S-acetoacetyl-CoA (Ki approximately 1.6 microM), as well as oxidation of 17beta-estradiol (Ki approximately 3.2 microM) and (-)-2-octanol (Ki approximately 2.6 microM). Because micromolar levels of Abeta were required to inhibit ERAB/HADH II activity, whereas Abeta binding to ERAB/HADH II occurred at much lower concentrations (Km approximately 40-70 nM), the latter more closely simulating Abeta levels within cells, Abeta perturbation of ERAB/HADH II was likely to result from mechanisms other than the direct modulation of enzymatic activity. Cells cotransfected to overexpress ERAB/HADH II and betaAPP(V717G) generated malondialdehyde-protein and 4-hydroxynonenal-protein epitopes, which were detectable only at the lowest levels in cells overexpressing either ERAB/HADH II or betaAPP(V717G) alone. Generation of such toxic aldehydes was not observed in cells contransfected to overexpress Y168G/K172G-altered ERAB and betaAPP(V717G). We conclude that the generalized alcohol dehydrogenase activity of ERAB/HADH II is central to the cytotoxicity observed in an Abeta-rich environment.     

Internal flow mechanism of cone-straight nozzle

Cone-straight nozzle has been widely used in well bore cleaning,assisting drilling in petroleum in-dustries due to its good clustering properties.The structure ...     

机制整体型全纤维炉衬台车炉技术改造

针对第一拖拉机股份有限公司锻造厂１０ 号车间７＃ 台车炉存在的能耗高、生产效率低等问题,采用“整体型全纤维炉衬”的专利技术进行技术改造,以达到节能降耗的目的。