LOW DENSITY LIPOPROTEIN (LDL) METABOLISM IN PRIMATE ATHEROSCLEROSIS

这一观察是在上一个资金期做出的，即单不饱和 脂肪不能预防冠状动脉粥样硬化，尽管 改善的低密度脂蛋白/高密度脂蛋白比率。由于这对公共卫生的意义 观察，我们建议用以下方法来确认和扩展这一观察 进一步的研究，同时试图定义 结果就会发生。一群非洲绿猴子将被喂食四种不同的食物 膳食脂肪(饱和、单一不饱和、n-6和n-3 多不饱和)来改变低密度脂蛋白颗粒组成。血浆低密度脂蛋白 胆固醇浓度将在饮食脂肪组中保持平衡，因此 低密度脂蛋白组成对冠状动脉扩张的影响 动脉粥样硬化可以直接评估。等离子体的光谱 将在每一只动物身上测量脂蛋白反应 研究和发展的冠状动脉粥样硬化的范围 在四年的饮食诱导期内也将进行测量，以便 脂蛋白与动脉粥样硬化的关系以及饮食中的脂肪酸 对此的影响是可以确定的。要检验的主要假设是 这个提议是成分修饰的，胆固醇油酸酯 富含低密度脂蛋白促进动脉粥样硬化 有促进胆固醇倾向的人数比例 在冠状动脉中积聚。检查如何在成分上 修饰的低密度脂蛋白可促进动脉粥样硬化的形成，各饮食组的低密度脂蛋白将 检测它们与动脉蛋白多糖(PG)的结合及其对 动脉平滑肌细胞产生PG。替代日粮中的n-3 饮食中的多不饱和脂肪酸可降低胆固醇 肝脏的油酸积累和分泌，以及增加的 胆固醇7α-羟基酶活性与游离胆固醇的降低 肝脏内容物。肝脏胆固醇代谢的两种酶，酰基- CoA：胆固醇酰基转移酶(ACAT)和C7H似乎是关键 用于确定整个肝脏的胆固醇平衡的调控站点。 肝脏ACAT(S)和C7H的调节研究将于 从喂食不同食物的猴子身上采集的连续肝脏活检， 在分离的猴肝细胞中与不同类型的脂肪酸和 胆固醇浓度，以及在离体肝灌流期间 从来自不同饮食组的动物身上分离出的肝脏。 越来越多的证据表明，肝脏中存在多种ACAT酶， 我们将鉴定和鉴定肝脏ACAT(S)，以确保 相关酶的调节是文件。最后，我们建议 检测低密度脂蛋白水平非常高的转基因小鼠的模型 以测试膳食脂肪酸对低密度脂蛋白组成和 动脉粥样硬化，由于ACAT和/或C7H的基因修改， 这个例子最终可以在老鼠身上进行测试。

This observation was made in the last funding period that mono-unsaturated fat did not protect against coronary artery atherosclerosis in spite of an improved LDL/HDL ration. Due to the public health significance of this observation, we propose to confirm and extend this observation with further studies, while attempting to define mechanisms through which the outcome occurs. Groups of African green monkeys will be fed four different dietary fats (saturated, mono-unsaturated, and n-6 and n-3 polyunsaturated) to modify LDL particle composition. Plasma LDL cholesterol concentrations will be balanced among dietary fat groups so that the effect of LDL composition on the extend of coronary artery atherosclerosis can be assessed directly. The spectrum of plasma lipoprotein responses will be measured in each of the animals in the study, and the extend of coronary artery atherosclerosis that develops over a four year period of diet-induction will also be measured so that any lipoprotein-atherosclerosis relationship, and dietary fatty acid effect thereon, can be identified. The main hypothesis to be tested in this proposal is that compositionally modified, cholesteryl oleate enriched low density lipoproteins promote atherosclerosis out of proportion of their number through a predisposition to promote cholesterol accumulation in the coronary arteries. To examine how compositionally modified LDL could promote atherogenesis, LDL from each diet group will be examined for their binding to arterial proteoglycans (PG) and effects on PG production by arterial smooth muscle cells. Substitution of dietary n-3 polyunsaturated fatty acids into the diet results in less cholesteryl oleate accumulation and secretion by liver, as well as an increased cholesterol 7alpha-hydroxylase (C7H) activity and reduced free cholesterol content of liver. The two liver cholesterol -metabolizing enzymes, acyl- CoA: cholesterol acyltransferase (ACAT) and C7H appear to be key regulatory sites for determining cholesterol balance across the liver. Study of the regulation of hepatic ACAT(s) and C7H will be carried out in sequential liver biopsies taken from monkeys fed different diets, and that in isolated monkey hepatocytes incubated with varying fatty acid types and cholesterol concentrations, and during isolated liver perfusion with livers isolated from animals from each of the different diet groups. Evidence is accumulating that there are multiple ACAT enzymes in liver, and we will identify and characterize the hepatic ACAT(s) to be sure that regulation of the pertinent enzyme is document. Finally, we propose to examine a transgenic mouse with very high LDL cholesterol levels a model in which to test the dietary fatty acid effects on LDL composition and atherosclerosis, since genetic modifications in ACAT and/or C7H, for example can eventually be tested in mice.