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Slide 10-1. The process of atherosclerosis results in the development of an unstable plaque in the wall of the coronary arteries which ruptures, leading to an acute thrombosis and myocardial infarction. Nutrition plays a major role in several aspects of this multicellular process through hormones that stimulate muscle cell proliferation, oxidant/antioxidant balance involved in the formation of plaque, cholesterol metabolism, and the clotting system which mediates the arterial blockage.

Slide 10-2 Lipids are carried in the blood by lipoprotein particles. These include LDL, VLDL, and HDL which are defined by their density in a preparative ultracentrifuge separation as low density (LDL), very low density (VLDL), and high density (HDL). It has now been shown that LDL can exist in a small dense form in which the ratio of apoprotein B-100 to cholesterol is elevated. This occurs commonly with upper body obesity and insulin resistance (see slide 10-30) . Lipoprotein(a) is also carried on LDL and can inhibit thrombolysis. It increases heart attack risk when it exists in the presence of other risk factors.

Slide 10-3. Here an LDL particle is shown with the polar heads of lipids oriented to the outside of the sphere. Triglycerides, cholesterol and phospholipids make up the shell. There is an apolipoprotein B-100 cap on the particle that serves as a recognition signal for the body to use in metabolizing this particle. Dietary lipids, by influencing plasma lipids, affect the lipid composition of these particles.

Slide 10-4. In over 50% of cases there is less than 50% blockage of the artery at the time of a heart attack. The yellow plaque consists of cholesterol crystals that have escaped from foam cells in the intima of the artery. These are disgorged by foam cells, which are monocyte scavenger cells that take up the oxidized cholesterol in the intima.

Slide 10-5. Triglycerides comprise 90% of the fats and oils in the diet. They are also produced endogenously in the liver and transported in the blood with very low density lipoprotein particles. Triglycerides can be burned in the muscle for energy or stored in fat cells through the action of the same enzyme, lipoprotein lipase. Triglycerides and cholesterol are increased in dietary-induced hyperlipidemias.

Slide 10-6. Individuals with familial hypercholesterolemia (FH) have abnormalities of the LDL receptor reflected in reduced metabolic clearance of cholesterol-containing lipoprotein from the blood. Shown here are the clearance curves for normal subjects, patients heterozygous for hypercholesterolemia, and patients with homozygous disease.

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