OXIDATION-INDUCED MEMBRANE DAMAGE IN CATARACTOGENESIS

细胞膜对阳离子的通透性增加，是一种常见的现象 在白内障中，导致细胞内离子失衡。氧化 蛋白质存在于人类老年性白内障中，导致交联物和 高分子量晶体蛋白聚集体的形成。这个 膜脂过氧化可能参与两种膜 通透性增加，蛋白质氧化。脂类更容易导致 比蛋白质氧化，产生过氧化中间体和游离 能引发蛋白质进一步氧化的自由基。我们假设 氧衍生的自由基是引发 早期通过诱导膜脂过氧化导致白内障的发生 膜损伤和蛋白质氧化事件。我们将决定 相对稳定的氧化剂氢的出现顺序 过氧化氢、过氧化脂质和细胞膜氧化产物 人类供体正常晶状体中的成分随年龄的变化 经手术摘除的白内障晶状体的放射性同位素和 酶偶联分光光度和荧光光谱技术。 脂质和过氧化脂质将通过高效液相色谱法及其加合物进行鉴定。 薄层扫描法。脂质过氧化产物和蛋白质的加合物将是 用柱层析法和凝胶电泳法进行分析。脂类修复 机制将使用放射性探测器来确定。形成了一种 缝隙连接等关键质膜蛋白中的二硫键交联 蛋白质，MIP26将用层析法和硫醇测定 分光光度法。钠、钾激活和钙激活的ATPase 将接受生化监测，以确定与年龄相关的活动丧失和 氧化。来检验氧化剂将加速和 抗氧化剂会延缓白内障的发展变化 Emory小鼠，人类老年性白内障的模型，我们将观察 饲喂硒对小鼠低水平氧化应激的影响 饮食，或抗氧化剂，乙酰水杨酸盐，在饮食中。

Increase in cell membrane permeability to cations, is a common occurrence in cataracts, leading to intracellular ionic imbalance. Oxidation of protein occurs in human senile cataract, leading to crosslinking and the formation of high molecular weight crystallin aggregates. The peroxidation of membrane lipids may participate in both membrane permeability increases and protein oxidation. Lipids are more prone to oxidation than proteins, generating peroxide intermediates and free radicals that can initiate further oxidation of proteins. We hypothesize that oxygen-derived free radicals are the agents that trigger cataractogenesis by inducing peroxidation of membrane lipids, an early event in both membrane damage and protein oxidation. We will determine the sequence of appearance of relatively stable oxidants, hydrogen peroxide, lipid peroxide and the products of oxidation of cell membrane components in human donor normal lenses as a function of age, and in surgically extracted cataractous lenses by radioisotopic and enzyme-coupled spectrophotometric and spectrofluorometric techniques. Lipids and lipid peroxides will be identified by HPLC and their adducts by TLC. Adducts of lipid peroxidation products and proteins will be analysed by column chromatography and gel electrophoresis. Lipid repair mechanisms will be determined using radioactive probes. The formation of disulfide crosslinks in key plasma membrane proteins such as gap junction protein, MIP26 will be measured chromatographically and thiols spectrophotometrically. Na+, K+-activated and Ca2+-activated ATPases will be monitored biochemically for age-related loss in activity and oxidation. To test the hypothesis that oxidants will accelerate and antioxidants will retard the development of cataractous changes in the Emory mouse, a model of human senile cataract, we shall observe the effects of a low level of oxidative stress by feeding selenium in the diet, or an antioxidant, acetylsalicylate, in diet.