OXIDANT MECHANISMS IN DRUG-INDUCED HEPATIC NECROSIS

许多毒素通过代谢产生化学活性物质来杀死细胞。 这些中间体反过来又会改变细胞分子， 损害细胞结构和功能，导致活力丧失。 在这些研究中观察到许多化学和生物化学变化， 其中，关键是在损害的启动。 然而，三个主要类别的组织改变是公认的： 烷基化、氧化和过氧化。 研究中的一个难点 氧化应激诱导的肝坏死一直缺乏动物 模型 尽管活性氧的参与机制 被提议用于由许多药物引起的组织损伤， 缺血后的再流，许多已知的机制， 通过该反应性氧物质杀死细胞， 在体外进行的研究，特别是在分离或培养的大鼠中进行的研究 肝细胞 我们已经发现敌草快在小鼠中产生中心球坏死。 雄性Fischer-344大鼠和一些证据表明， 坏死是由活性氧物质的产生介导的。 这 模型已被进一步研究，以了解在 其中活性氧物质和氧化应激在体内杀死细胞， 开发用于区分这些细胞实例的定量标准 体内死亡，可能是由氧化剂机制介导的， 其致死作用是通过其他机制表达的。 急性肝坏死敌草快模型的研究已经 证明了一些重要的差异，从产生的假设， 体外研究，特别是细胞内转移的作用， 巯基/二硫化物比率和蛋白质巯基的消耗。 这些研究 的敌草快模型揭示了一个明显的关键作用，脂质 过氧化反应在体内表达活性氧损伤， 铁的化学反应性螯合物的可用性似乎是 过氧化损伤和细胞死亡的基本决定因素。 研究 本提案中所述的化学物质， 分析方法，以调查在何种程度上，脂质 过氧化作用是敌百虫诱导的体内肝坏死的原因， 在这些过程中，化学反应性铁物质所起的作用。 这些方法和办法以及在1998年制定的定量标准， 这些研究将被应用于对假设的批判性检验 氧化应激机制导致肝坏死， 对乙酰氨基酚和四氯化碳。 因为后两个探员 是如此重要的模型肝毒素，拟议的研究是针对 这些问题对于我们理解细胞的机制至关重要， 体内死亡

Many toxins kill cells by the metabolic generation of chemically reactive intermediates that in turn produce alterations in cellular molecules, compromising cell structure and function, leading to loss of viability. Many chemical and biochemical changes are observed in such studies, not all of which are involved critically in the initiation of damage. Nevertheless, three major classes of tissue alteration are recognized: alkylation, oxidation, and peroxidation. A difficulty in the study of oxidant stress-induced hepatic necrosis has been the lack of an animal model. Although the mechanistic involvement of reactive oxygen species has been proposed for tissue damage initiated by a number of drugs and by reflow following ischemia, much of what is known about the mechanisms through which reactive oxygen species kill cells has been developed in studies conducted in vitro, particularly in isolated or cultured rat hepatocytes. We have found that diquat produces centribolular necrosis in male Fischer-344 rats and several lines of evidence indicate that this necrosis is mediated by the generation of reactive oxygen species. This model has been studied further in an effort to understand the manner in which reactive oxygen species and oxidant stress kills cells in vivo and to develop quantitative criteria for distinguishing those examples of cell death in vivo that may be mediated by oxidant mechanisms from those in which the lethal effects ar expressed through other mechanisms. Investigations of the diquat model of acute hepatic necrosis have demonstrated some important differences from the hypotheses generated from studies in vitro, particularly the role of shifts in cellular thiol/disulfide ratios and the depletion of protein thiols. These studies of the diquat model have revealed an apparently critical role of lipid peroxidation in the expression of reactive oxygen injury in vivo, and that the availability of chemically reactive chelates of iron appears to be an essential determinant of peroxidation damage and cell death. The studies described in this proposal are designed to apply chemically specific methods of analysis to the investigation of the extent to which lipid peroxidation is responsible for diquat-induced hepatic necrosis in vivo and the role played by chemically reactive iron species in these processes. These methods and approaches and the quantitative criteria developed in these studies will be applied to a critical examination of the hypothesis that oxidant stress mechanisms contribute to hepatic necrosis initiated by acetaminophen an by carbon tetrachloride. Because the latter two agents are such important model hepatotoxins, the proposed studies are directed at issues that are fundamental to our understanding of the mechanisms of cell death in vivo.