OXIDANT MECHANISMS IN DRUG INDUCED HEPATIC NECROSIS

活性氧物种和自由基被认为是导致 与人类疾病相关的许多不良反应和 毒性，但这些毒性的确切机制 没有得到充分的理解。该计划的主要目标是 在本申请中描述的研究是确定这些 机械装置。有证据表明，失去对铁的体内平衡控制， 而氧化还原活性铁络合物催化的氧化反应可能是 活性氧在组织损伤中的关键作用，但更具特异性 生物标志物和对这一假说越来越关键的测试是必要的。 其他研究人员已经证实，蛋白质硫醇的损失在 氧化损伤的机制，通常是在病情恶化的基础上 可能是1，3-二(2-氯乙基)-N-亚硝脲(BCNU)造成的伤害 通过抑制谷胱甘肽还原酶起作用。然而，标记为 在我们的研究中没有观察到蛋白质硫醇/二硫键状态的变化 活性氧介导的组织损伤。蜂窝 分子水平上的区隔或特异性可能是 显著的硫醇/二硫键位移，以及分子生物学 本申请中描述的方法提供了 测试这些假设，以避免 BCNU.在我们最近的研究中有一个特别重要的观察结果 已经提供了对氧化剂的戏剧性保护 线粒体中谷胱甘肽还原酶活性的增加，这是 表明这个隔间的硫醇/二硫化物状态是一个主要的 细胞活性的决定因素。拟议中的研究也将检验 假设硫醇/二硫键的位移被隔开到 研究表明，线粒体对体内氧化细胞损伤有贡献 辅酶A及其混合二硫化物，并通过直接评估 蛋白质硫醇。扑热息痛的剂量低于正常治疗剂量 在人类使用的剂量，反应性代谢物与DNA共价结合 小鼠肝脏和肾脏的活体实验。不会通过以下方式阻止绑定 谷胱甘肽和最近报道的终末期风险的相关性 累积生活方式摄入对乙酰氨基酚的肾脏疾病 提示扑热息痛的剂量可能与 引起剧烈的坏死。了解导致以下问题的因素 生物性暴露于活性氧物种、自由基和其他 氧化剂，这些活性中间体通过的机制 改变生物分子，以及生化和病理生理学 各自变更的后果是重要的基本原则 生物化学研究的目标和长期目标 本申请中描述的研究。

Reactive oxygen species and free radicals are thought to contribute to many of the adverse effects associated with human diseases and toxicities, but the precise mechanisms through which these toxicities are expressed are not understood adequately. The principle goal of the research described in the present application is to determine these mechanisms. Evidence suggests that loss of homeostatic control of iron, and the oxidations catalyzed by redox-active iron chelates, may be pivotal in tissue damage by reactive oxygen species, but more specific biomarkers and increasingly critical tests of the hypothesis are needed. Other investigators have implicated the loss of protein thiols in mechanisms of oxidant injury, frequently on the basis of exacerbation of injury with 1,3-bis(2-chloroethyl)-N-nitrosourea (BCNU), presumably acting through inhibition of glutathione reductase. However, marked shifts in protein thiol/disulfide status are not observed in our studies of reactive oxygen-mediated tissue injury. Cellular compartmentalization or specificity at the molecular level may be significant in thiol/disulfide shifts, and the molecular biological approaches described in the present application provide approaches to testing these hypotheses that also avoid the nonspecific effects of BCNU. A particularly significant observation in our more recent studies has been the dramatic protection against oxidants afforded by selective increases in activities of glutathione reductase in mitochondria, which suggest that the thiol/disulfide status of this compartment is a major determinant of cellular viability. The studies proposed also will test the hypothesis that thiol/disulfide shifts compartmentalized to the mitochondria contribute to oxidant cell injury in vivo, through studies of coenzyme A and its mixed disulfides, and by direct assessments of protein thiols. At doses of acetaminophen below the normal therapeutic doses used in humans, reactive metabolites bind covalently to DNA in mouse liver and kidney in vivo. The binding is not prevented by glutathione, and the recently reported correlation of risk for end stage renal disease with cumulative lifestyle ingestion of acetaminophen suggests a potential relevance of doses of acetaminophen that do not cause necrosis acutely. Understanding the factors responsible for biological exposure to reactive oxygen species, radicals, and other oxidants, the mechanisms through which these reactive intermediates alter biological molecules, and the biochemical and pathophysiological consequences of the respective alterations are important fundamental goals of biochemical research and are the long-term goals of the research described in the present application.