Relationship between lipoprotein- and oxidation-related variables and atheroma lipid composition in subjects undergoing coronary artery bypass graft surgery.

The relationship between atheroma lipid composition and serum lipoprotein and oxidation measurements has not been fully explored. To address this question, we studied serum, plasma, and aortic wall specimens from 66 subjects undergoing coronary artery bypass graft surgery. The lipid composition of aortic specimens was characterized in terms of cholesterol ester and cholesterol crystal plus phospholipid by using hot-stage polarizing light microscopy; tissue oxidation status was assessed by measuring conjugated dienes. Serum lipoprotein-related measurements included total cholesterol, triglyceride, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, apolipoproteins B and AI, and lipoprotein(a). Oxidation status was assessed by measuring LDL mobility, thiobarbituric acid-reactive substances, LDL conjugated dienes, and IgG and IgM autoantibodies against oxidized LDL. Fasting blood glucose was also determined. Lesion cholesterol crystal plus phospholipid content was associated inversely with serum HDL cholesterol levels (r=-0.279, P=0.029) and positively with fasting blood glucose (r=0.359, P=0.016), LDL mobility (0.276, P<0.05), and IgM autoantibodies against oxidized LDL (r=0.272, P=0.037). There was also a significant relationship between the level of aortic tissue conjugated dienes and plasma LDL mobility (r=0.332, P=0.007). In multivariate analysis, IgM autoantibodies against oxidized LDL, fasting blood glucose, and LDL mobility, in descending order of significance, together accounted for 35% of the variability in aortic lesion cholesterol crystal plus phospholipid content. These data support direct and independent roles for oxidation and hyperglycemia in the pathophysiology of atherosclerosis.

Direct measurement of serum low-density lipoprotein cholesterol in patients with acute myocardial infarction on admission to the emergency room.

Measurement of low-density lipoprotein cholesterol during acute myocardial infarction in nonfasting patients on initial presentation to an emergency room by any of 3 methods (ultracentrifugation, immunoseparation, or the Friedewald estimate), identifies patients eligible for antilipemic interventions. Although slightly less sensitive, the conventional Friedewald estimate of low-density lipoprotein cholesterol levels provides clinicians good correlation with ultracentrifugation.

Vitamin E does not modify HDL-cholesterol.

Vitamin E has been reported to increase serum high-density lipoprotein (HDL) cholesterol. Given the known inverse relationship between HDL-cholesterol and risk of developing coronary artery disease, these preliminary results require verification or refutation. In the present study, 39 volunteers were given 600 U of vitamin E daily for 30 days. Serum vitamin E, cholesterol, HDL-cholesterol, and triglycerides were measured at appropriate intervals. No significant change in serum HDL-cholesterol with vitamin E therapy could be documented.