Treatment with lovastatin plus diet slows the rate of progression and increases the frequency of regression in coronary artery lesions (by global change score), especially in more severe lesions (by quantitative angiography). This is the third lipid-lowering trial to show a benefit using the global change score, an end point predictive of clinical coronary events. Differences between two of these trials, using quantitative coronary angiographic end points, may have theoretical bearing on the mechanisms by which lipid-lowering therapy operates at the level of the arterial wall.

These results indicate that triglyceride-rich lipoproteins and cholesterol-rich lipoproteins have a differential effect on mild/moderate and severe lesion progression, respectively. These results add to the growing evidence of the importance of triglyceride-rich lipoproteins as a risk factor for coronary artery disease and the need for treatment in the progression of atherosclerosis.

Diet-induced atherosclerosis in macaque monkeys was suppressed by anticalcifying agents without changing abnormal levels of blood cholesterol and lipoprotein. The agents included inhibitors of arterial calcium deposition (diphosphonates) and a calcium ion antagonist (lanthanum). The study suggests that regulation of calcium flux and extracellular deposition in arteries may offer new principles of treatment for cardiovascular disease.

A B S T R A C T Elastin preparations from intimal layers and the media of normal and atherosclerotic human aortae were analyzed for protein and lipid content. In atherosclerotic aortae, elastin from plaques was compared with elastin from adjacent normal appearing areas of the same aorta.Arterial elastin purified by alkaline extraction appeared to be a protein-lipid complex containing free and ester cholesterol, phospholipids, and triglycerides. The lipid component of normal arterial elastin was small (1-2%). With increasing severity of atherosclerosis, there was a progressive accumulation of lipid in intimal elastin from plaques, reaching a mean lipid content of 37% in severe plaques. The increase in the lipid content of plaque elastin preparations wvas mainly due to large increases in cholesterol, over 80% of which was cholesteryl ester. This deposition of cholesterol in plaque elastin accounted for 20-34% of the total cholesterol content of the plaque. The increased lipid deposition in plaque elastin was associated with alterations in the amino acid composition of plaque elastin. In elastin from plaque intima, the following polar amino acids were increased significantly: aspartic acid, threonine, serine, glutamic acid, lysine, histidine, and arginine; whereas, cross-linking amino acids: desmosine, isodesmosine, and lysinonorleucine were decreased significantly. The amino acid and lipid composition of elastin from normal appearing aortic areas was comparable to that of normal arterial elastin except for intimal elastin directly adjacent to and medial elastin directly below the most severe plaques.

A B S T R A C T Coarctation of the mid-thoracic aorata was surgically produced in mongrel dogs which were sacrificed from 4-12 wk after the operation. As compared to the findings in control animals, the sodium, chloride, and water content of the hypetensive portion of the coarcted thoracic aorta was significantly elevated, whereas the electrolyte and water content of the relatively normotensive portion of the coarcted aorta was normal. The sodium, potassium, and water content of the pulmonary artery, skeletal muscle, and cardiac muscle of the coarcted dog was not altered. These observations suggest that an elevated arterial pressure may influence the electrolyte and water composition of the arteries.The arterial pressure also may influence the content and synthesis of acid mucopolysaccharides (MPS) in the arteries since the content of sulfated MPS and the incorporation of injected radiosulfate into sulfated MPS were significantly increased in, the hypertensive portion of the coarcted thoracic aorta but were significantly reduced in the relatively normotensive ("hypotensive") portion of the coarcted aorta. The observed increase in MPS may have been a factor directly responsible for the increase in the sodium content of the hypertensive aorta since MPS can act as polyelectrolytes and bind cations.Although the arterial pressure may influence certain metabolic functions in the arteries, it did

In 1904, Marchand recognized the consistent association of fatty degeneration and vessel stiffening and introduced the term "atherosclerosis" to indicate this combination. Current research is focused principally on the lipid component, but there is evidence that both aspects are reversible. Atheromatous lipids add significantly to the volume of lesions and thus contribute to vascular obstruction and end-organ damage. Reversal of atherosis has been observed in all the major species used in atherosclerosis research; rabbits, swine, dogs, chicks, pigeons, and subhuman primates. Direct evidence for reversal in humans is based on angiographic trials and is less extensive. One femoral artery and one coronary artery trial indicate that the lesions can be stabilized. CLAS, the largest angiographic trial to date, indicates that coronary lesion reversal is possible. Clinical effects of sclerosis are more subtle, and there is little evidence that sclerosis alone leads to end-organ damage. However, it should be noted that atherosclerotic lesions producing end-organ damage invariably have a major fibrous component. Sclerotic vessels have reduced systolic expansion and abnormally rapid pulse wave propagation, which can be measured noninvasively. Primate studies indicate that sclerosis is induced by hypercholesterolemic diets and is reversible when these diets are withdrawn. Changes in sclerosis may be another useful indicator of the formation and reversal of lesions and may involve changes in EDRF. Future studies of atherosclerosis reversal should use a combination of measures to evaluate both atherosis and sclerosis.

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