METHANOL POISONING

本项目的目的是揭示黄曲霉毒素的作用机制 人体内的甲醇中毒。据我们所知，只有人类和 猴子表现出特有的甲醇毒性，但毒性较低 动物，老鼠和大鼠，都不会。本实验室以前的工作 研究表明，猴子体内甲酸盐氧化的速度较慢 而肝脏中的四氢叶酸水平 对甲酸盐氧化的重要性在猴子中要低得多 在老鼠身上。 目前的建议是，首先，检查稳态 肝叶酸衍生物及其中间体的水平 叶酸生化途径。人体组织将由以下机构提供 器官移植捐赠者先和后由患者接受 上消化道手术。程序将包括快速 冷冻肝脏，然后进行高效液相分离和 用微生物生物测定法进行定量。低浓度的 人肝四氢叶酸和可能的低总肝 预计会有叶酸。这将支持这样的假设： 甲酸盐氧化在一定程度上取决于肝脏中 四氢叶酸。这些实验将与研究进行比较 对小鼠肝脏中叶酸水平的影响。小鼠代谢甲酸的速率 这是在老鼠身上观察到的三倍。我们假设肝脏 四氢叶酸在小鼠肝脏中的水平可能要高得多。 第二系列项目将研究酶的调节。 通过叶酸催化甲酸氧化成二氧化碳 系统；具体地说，以甲酰四氢叶酸为主导的调解 合成酶和甲酰四氢叶酸脱氢酶。人类 肝酶将在#年进行定量和定性研究。 胞质组分和均一状态。动能 实验和免疫定量实验将是 使用大鼠、小鼠和人的肝脏制剂进行实验。后来, 将进行分子生物学研究，以检查 这些蛋白质的合成可能存在基因调控。 还建议进行研究，以评估对 肝脏中的四氢叶酸水平。亚甲基的酶学研究 四氢叶酸还原酶、蛋氨酸合成酶和丝氨酸 羟甲基转移酶是人类肝脏的一种酶。 这些研究应该为监管提供洞察力 动物体内的甲酸和叶酸代谢，特别是在 人类。

The objective of this project is to reveal the mechanism of methanol poisoning in humans. To our knowledge only humans and monkeys display characteristic methanol toxicity whereas lower animals, mice and rats, do not. Previous work in this laboratory has shown that the rate of formate oxidation is slower in monkeys than in rats and that hepatic tetrahydrofolate levels which are important for formate oxidation are much lower in monkeys than in rats. The current proposal is designed, first, to examine steady-state levels of hepatic folate derivatives and intermediates of the folate biochemical pathway. Human tissues will be provided by organ transplant donors first and later by patients undergoing upper gastrointestinal surgery. Procedures will include rapid freezing of livers followed by HPLC separations and quantification by microbiological bioassay. Low concentrations of human hepatic tetrahydrofolate and possibly low total hepatic folate is expected. This would lend support to the hypothesis that formate oxidation depends, in part, on hepatic levels of tetrahydrofolate. These experiments will be compared to studies on folate levels in mouse liver. Mice metabolize formate at rates three times the rates observed in rats. We postulate that hepatic tetrahydrofolate levels may be much higher in mouse liver. A second series of projects will examine the enzymatic regulation of formate oxidation to CO2 as catalyzed through the folate system; specifically the mediation led by formyltetrahydrofolate synthetase and formyltetrahydrofolate dehydrogenase. Human liver enzymes will be studied quantitatively and qualitatively in cytosolic fractions and in the homogeneous state. Kinetic experiments and immunoquantitative experiments will be performed using rat, mouse and human liver preparations. Later, molecular biological studies will be performed to examine the possible genetic regulation of synthesis of these proteins. Studies are also proposed to evaluate the regulation of tetrahydrofolate levels in liver. Enzymatic studies on methylene tetrahydrofolate reductase, methionine synthetase and serine hydroxymethyltransferase are described for human liver. These studies should provide insights into the regulation of formate and folate metabolism in animal species, especially in humans.