OXIDANT MECHANISMS IN DRUG INDUCED HEPATIC NECROSIS

活性氧物质和自由基被认为有助于 与人类疾病有关的许多不利影响， 但是这些毒性的确切机制 表达得不够清楚。的主要目标 本申请中描述的研究是确定这些 机制等 有证据表明，失去对铁的稳态控制， 以及由氧化还原活性铁螯合物催化的氧化，可以是 在活性氧引起的组织损伤中起关键作用， 需要生物标志物和越来越严格的假设检验。 其他研究者认为， 氧化损伤的机制，通常是基于恶化 1，3-双（2-氯乙基）-N-亚硝基脲（BCNU）的损伤，推测 通过抑制谷胱甘肽还原酶起作用。 然而，标记 在我们的研究中没有观察到蛋白巯基/二硫键状态的变化 活性氧介导的组织损伤 蜂窝 在分子水平上的区室化或特异性可以是 在巯基/二硫键位移中具有显著性， 本申请中描述的方法提供了 测试这些假设，也避免了非特异性的影响， BCNU. 在我们最近的研究中， 是选择性的抗氧化剂 线粒体中谷胱甘肽还原酶活性增加， 表明该隔室的硫醇/二硫化物状态是主要的 细胞活力的决定因素。 拟议的研究还将测试 假设硫醇/二硫键转移区室化到 线粒体有助于体内氧化细胞损伤，通过研究 辅酶A及其混合二硫化物，并通过直接评估 蛋白质硫醇 对乙酰氨基酚的剂量低于正常治疗剂量 在人体中使用的剂量下，反应性代谢物与DNA共价结合， 小鼠体内肝脏和肾脏。 结合不会被阻止， 谷胱甘肽，以及最近报道的终末期风险的相关性 肾脏疾病伴对乙酰氨基酚的累积性生活方式摄入 表明对乙酰氨基酚剂量的潜在相关性 引起急性坏死。 了解导致 生物暴露于活性氧、自由基和其他 氧化剂，这些反应中间体 改变生物分子，以及生物化学和病理生理学 各自的变化的后果是重要的基本 生物化学研究的目标，是长期的目标， 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.