LIPID HYDROPEROXIDE CYTOTOXICITY AND DETOXIFICATION

描述：脂质氢过氧化物 (LOOH) 可能有害 活性氧攻击不饱和脂质产生的中间体， 磷脂 (PL) 和细胞膜中的胆固醇。 单线态氧 () 衍生的 LOOH 由于日益受到关注而受到特别关注 关于 2 介导的光动力作用引起的皮肤光毒性 可见辐射或长波紫外线辐射。 建议 细胞膜中产生或获得的 LOOH 可以经历 (i) 谷胱甘肽/硒过氧化物酶（GSH/GPX）介导的双电子还原 相对无害的酒精（解毒）或（ii）铁介导的 单电子还原导致连锁反应加剧 过氧化损伤，可能最终导致细胞凋亡或程序化细胞 死亡（毒性增强）。 关于影响因素的信息有限 可能会影响细胞中途径 (i) 和 (ii) 之间的 LOOH 分配 暴露于过氧化应激。 这个问题将由 以全面的方式研究这两条途径，首先使用 将胆固醇 LOOH 和 PLOOH 纳入模型膜中，然后 各种肿瘤细胞系中的光生对应物。 几种技巧 该实验室开发的产品将被使用，包括（i）高性能 液相色谱汞阴极电化学检测 [HPLC-EC(Hg)] 用于高灵敏度监测 LOOH 解毒，以及 (ii) 薄层色谱与荧光成像放射检测 (TLC-PI) 用于评估 LOOH 链引发效力 (CIP)，该指数反映 “报告者”脂质的氧化程度，例如[14C]胆固醇。 这些 将使用方法来确定细胞的变化如何 硒、铁或α-生育酚状态可能会影响LOOH的解毒作用 一方面，毒性增强导致细胞凋亡 另一个。 这些研究旨在提供有关 具有重要生物学意义的 LOOH 的动态以及细胞如何响应 1O2 和其他活性物质带来的过氧化挑战。

DESCRIPTION: Lipid hydroperoxides (LOOHs) are potentially deleterious intermediates generated by activated oxygen attack on unsaturated lipids, phospholipids (PLs), and cholesterol in cell membranes. Singlet oxygen ()-derived LOOHs are of special interest because of the growing concern about cutaneous photoxicity resulting from 2-mediated photodynamic action of visible radiation or long wavelength ultraviolet radiation. It is proposed that LOOHs generated in or acquired by cell membranes can either undergo (i) glutathione/selenoperoxidase (GSH/GPX)-mediated two-electron reduction to relatively innocuous alcohols (detoxification) or (ii) iron-mediated one-electron reduction resulting in chain reactions that exacerbate peroxidative injury, possibly culminating in apoptotic or programmed cell deat (toxicity enhancement). Information is limited about the factors that might affect LOOH partitioning between pathways (i) and (ii) in a cell exposed to peroxidative stress. This question will be addressed by investigating both pathways in comprehensive fashion, first using cholesterol LOOHs and PLOOHs incorporated into model membranes and then photogenerated counterparts in various tumor cell lines. Several techniques developed in this laboratory will be used, including (i) high performance liquid chromatography with mercury cathode electrochemical detection [HPLC-EC(Hg)] for high-sensitivity monitorin of LOOH detoxification, and (ii) thin layer chromatography with phophorimaging radiodetection (TLC-PI) for assessing LOOH chain initiation potency (CIP), an index reflecting the degree of oxidation of a "reporter" lipid, e.g. [14C] cholesterol. These approaches will be used in an effort to ascertain how changes in cellular selenium, iron, or a-tocopherol status might affect LOOH detoxification on the one hand, and toxicity enhancement leading to apoptotic cell death on the other. The studies are intended to provide new information about the dynamics of biologically important LOOHs and how cells respond to peroxidative challenges imposed by 1O2 and other activated species.