Update on the pathogenesis of atherosclerosis
Article Abstract:
When a patient dies of heart disease, it is not uncommon to see the blood vessels in the heart blocked by atherosclerotic plaques (''hardening'' of the arteries). In advanced disease, these fatty, yellowish, cholesterol-containing lesions have replaced much of the normal lining of the critical arteries that deliver blood to the heart (coronary arteries) and of vessels elsewhere in the body. A report is presented from a nationwide study of risk factors for atherosclerotic disease in young people. In addition, the factors that determine the progression of these lesions are reviewed. One approach to studying the progression of atherosclerosis is to look at the blood vessels of young people who have died of causes unrelated to heart disease or blood vessel disorders (usually, in traffic accidents or other injuries): this can provide insights into the very earliest stages of atherosclerosis. To this end, investigators organized PDAY (Pathological Determinants of Atherosclerosis in Youth), a multicenter study designed to compare the structure of blood vessels from subjects aged 15 to 34. Results indicate that, although high blood cholesterol levels contribute greatly to the development of heart disease, most young people with advanced atherosclerosis have had more moderately elevated levels of low-density lipoproteins (the ''bad'' form of cholesterol) that persisted over a long period of time. Another finding is that there seem to be two pathways for the development of atherosclerosis. In one of these pathways, eccentric plaques build up largely within the intima (the innermost layer of the artery), between the smooth muscle and the single layer of lining (endothelial) cells. The second pathway involves a concentric (affecting most of the circumference of the artery) inflammatory lesion that damages the layer of endothelial cells lining the artery. The former pathway appears to be reversible: evidence indicates that returning to a low-fat diet results in the reduction of even advanced atherosclerotic plaques of the first sort, but the second pathway of atherosclerotic progression (tentatively dubbed atheroarteritis) does not appear to regress and may be associated with more rapid progression of arterial disease. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1991
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Salt-sensitive blood pressure and exaggerated vascular reactivity in the hypertension of diabetes mellitus
Article Abstract:
The effects of low- and high-sodium diets were examined in patients with non-insulin-dependent diabetes mellitus (NIDDM) with and without hypertension (high blood pressure). The ability of salt to increase blood pressure was compared with blood vessel responses to angiotensin II, a natural substance that constricts blood vessels, thereby raising blood pressure. Nineteen patients with NIDDM, including seven with normal blood pressure and 12 with hypertension, and seven normal nondiabetic subjects were assessed after a six-day, low-sodium diet and again after a six-day, high-sodium diet. Salt sensitivity of blood pressure was indicated by an increase in 24-hour blood pressure values on changing from a low-sodium to a high-sodium diet. Eight of 12 hypertensive patients with NIDDM showed increased blood pressure on the high-salt diet. Patients with NIDDM had greater blood pressure responses to angiotensin II than normal subjects. Angiotensin II caused less blood vessel constriction in normal subjects on a low-sodium diet, but maintained its effect in patients with NIDDM. Patients with NIDDM also retained more sodium than normal subjects during the high-sodium diet. The findings indicate that hypertensive patients with NIDDM show salt sensitivity of blood vessel responses, possibly due to increased sodium retention and blood vessel reactivity to angiotensin II. But since low-sodium diets do not decrease the reactivity of the blood vessels to angiotensin II, salt restriction may be less effective for controlling blood pressure in hypertensive patients with NIDDM than it is in nondiabetics. More research is needed in which hypertensive diabetic patients follow a salt restriction for a longer period of time. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1990
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