MECHANISMS OF RADIOPROTECTION & TOXICITY OF SH COMPOUNDS

本项目旨在阐明 辐射损伤与修复 硫醇 具体目标涉及两个相互关联的领域： 辐射防护和硫醇毒性。 辐射防护研究 将研究（1）硫醇和氧的重要性 在确定辐射防护程度的浓度， 硫醇，从而测试损害的适用程度 修复固定竞争模型和相关模型， 辐射防护;（2）机制的一般性 硫醇中的辐射防护与不同的化学品和生化 与O2、OH、有机自由基、H2 O2、金属等的反应性;（三） 辐射诱导的细胞杀伤与 DNA损伤，尤其是双链断裂， 通过硫醇修饰该关系;以及（4） 硫醇参与辐射损伤的酶修复过程 细胞 毒性研究将建立控制条件 硫醇生成的过氧化物，以便使用硫醇 适当地在辐射防护实验中或作为一种手段， 产生活性氧。 这项研究与健康有关。 由于其潜在的应用保护， 癌症放疗或核灾难的辐射防护。 此外，硫醇研究与当前的兴趣相关 氧自由基作为化学疗法中的破坏剂， 致癌、衰老和关节炎。 将使用两种细胞研究辐射防护和毒性。 存活和DNA损伤测定。 将测量细胞存活率 在啮齿动物和人肿瘤细胞中使用经典的克隆形成测定 线 DNA损伤测量将使用洗脱进行 技术. 用于生存和DNA研究的细胞将被 使用悬浮液和薄层技术照射。 修复 研究包括DNA修复的测量， 损伤修复、亚致死损伤修复和修复缺陷的使用 哺乳动物细胞 使用的硫醇是二硫苏糖醇， 谷胱甘肽和半胱胺及其衍生物，包括WR-1065。 所有研究将被设计为控制氧气水平和金属- 催化的硫醇氧化，并形成过氧化物。

This project is designed to elucidate the molecular mechanisms of radiation-induced damage and repair as modified by exogenous thiols. The specific aims involve two interrelated areas: radioprotection and thiol toxicity. The radioprotection research will investigate (1) the importance of thiol and oxygen concentrations in determining the degree of radioprotection by thiols, thus testing the degree of applicability of the damage repair-fixation competition model and relate models to radioprotection; (2) the generality of mechanisms of radioprotection in thiols with varying chemicals and biochemical reactivities with 02, OH, organic radicals, H202, metals, etc.; (3) the relationship between radiation-induced cell killing and production of DNA damage, especially double strand breaks, and modification of that relationship by thiols; and (4) the involvement of thiols in enzymatic repair processes in irradiated cells. The toxicity studies will establish conditions for control of thiol-generated peroxide in order that the thiols are used properly in the radioprotection experiments or as a means to generate reactive oxygen species. The research has health-related implications because of its potential application to protection in cancer radiotherapy or radioprotection from nuclear disaster. Furthermore, the thiol studies are relevant to the current interest in oxygen radicals as damaging agents in chemotherapy, carcinogenesis, aging and arthritis. Radioprotection and toxicity will be studied using both cell survival and DNA damage assays. Cell survival will be measured using classical clongenic assays in rodent and human tumor cell lines. DNA damage measurements will be made using elution techniques. Cells for both survival and DNA studies will be irradiated using suspension and thin-layer techniques. The repair studies include measurements of DNA repair, potentially lethal damage repair, sublethal damage repair, and use of repair-deficient mammalian cells. The thiols to be used are dithiothreitol, glutathione, and cysteamine and its derivatives, including WR-1065. All studies will be designed to control for oxygen level and metal- catalyzed thiol oxidation, and resulting peroxide formation.