Oxidant stress & ascorbic acid processing in diabetes

项目#2：糖尿病中的氧化应激和抗坏血酸处理项目的目的是研究氧化应激和羰基应激在糖尿病并发症发病机制中的作用。特别地，这个项目（项目2）试图验证一个假设，即与糖尿病人相比，组织培养和糖尿病大鼠中由高葡萄糖引起的氧化应激主要依赖过渡金属和醛糖还原酶。此外，我们假设许多被认为作为醛糖还原酶抑制剂、抗糖化剂、生长因子、NO合成酶、PKC和其他抑制剂的药物在大鼠中作为过渡金属螯合剂和/或抗氧化剂具有有益的作用。我们建议通过使用一种非常强大的探针来评估体内氧化应激，即6-脱氧-6-氟抗坏血酸（f -抗坏血酸），结合750 MHz 19F-核磁共振光谱，同时提供抗坏血酸在体内分解代谢及其由糖尿病调节的第一个生化洞察，来验证这些假设。1. 测定体外低糖和高糖环境下F-抗坏血酸降解产物的化学性质和形成机制。2：确定与糖尿病并发症有关的细胞中f -抗坏血酸降解的代谢途径如何受到高糖环境的影响；确定大鼠和人类糖尿病如何影响抗坏血酸加工，以及是否发现异常预测大鼠和DCCT患者糖尿病并发症的发展。使用这种新方法，我们希望澄清一个关键问题：为什么大量药物在糖尿病大鼠中成功，但在人类中失败，这是由于糖尿病大鼠特有的氧化应激正常化，以及如此压倒性的强度，它掩盖了人类糖尿病诱导并发症的其他机制。如果得到证实，这一结果将对基于高血糖大鼠模型的抗糖尿病治疗的未来发展产生深远的影响。

Project #2: OXIDANT STRESS AND ASCORBIC ACID PROCESSING IN DIABETES The objective of the Program Project is to investigate the role of oxidative and carbonyl stress in the pathogenesis of diabetic complications. In particular, this project (Project 2) seeks to test the hypothesis that the oxidative stress resulting from high glucose in tissue culture and the diabetic rat is, in contrast to the diabetic human, primarily transition metal and aldose reductase dependent. Furthermore, we hypothesize many of the drugs thought to act as aldose reductase inhibitors, anti-glycating agents, growth factors, NO synthase, PKC and other inhibitors have beneficial effects in the rat as transition metal chelators and/or antioxidants. We propose to test these hypotheses by using a very powerful probe for assessment of oxidative stress in vivo, i.e 6-deoxy-6- fluoro ascorbic acid (F-ascorbate) in conjunction with 750 MHz 19F- NMR-spectroscopy, while at the same time providing the first biochemical insight into ascorbate catabolism in vivo and its modulation by diabetes. 1. To determine the chemical nature and mechanism of formation of F- ascorbate degradation products formed in vitro in low and high glucose environment. 2: To determine how the metabolic pathways of F-ascorbate degradation in cells implicated in diabetic complications are influenced by high glucose environment, and 3. To determine how diabetes in the rat and the human affects ascorbate processing, and whether uncovered abnormalities predict development of diabetic complications in the rat and DCCT patient. Using this novel approach, we expect to clarify the critical question: Is the reason why a large number of drugs have been successful in the diabetic rat but have failed in the human due to normalization of oxidative stress that is specific to the diabetic rat and of such overwhelming intensity that it masks other mechanisms of diabetes induced complications in the human. If confirmed, this outcome would have a profound effect on the future development of anti-diabetic therapies based on the rat model of hyperglycemia.