Effects of pregnancy, postpartum lactation, and oral contraceptive use on the lipoprotein cholesterol/triglyceride ratio

Lipoprotein cholesterol/triglyceride ratio changes have been observed previously with sex hormone use. To determine if the lipoprotein cholesterol/triglyceride ratio is similarly changed by pregnancy and postpartum lactation, we examined pregnant subjects at 36 weeks gestation and the same women at 6 weeks postpartum and compared them to age-matched, nonpregnant women using or not using oral contraceptives. The cholesterol/triglyceride ratios were examined as means and medians and as curvilinear functions of increasing triglyceride concentration. Median ratios did not predict all ratio changes identified graphically. At very-low-density lipoprotein (VLDL) triglyceride concentrations below 40 mg/dL, the VLDL ratio is less than control in oral contraceptive users and further reduced in pregnant women. Above triglyceride concentrations of 40-60 mg/dL, the curves in the three groups are indistinguishable. No effect of lactation is observed. The low-density lipoprotein (LDL) cholesterol/triglyceride ratio is comparably lower in pregnant subjects and oral contraceptive users at all concentrations of lipoprotein triglyceride and again there is no effect of lactation. In high-density lipoprotein (HDL), there is no effect of either pregnancy or oral contraceptive use on the cholesterol/triglyceride ratio, while it is significantly higher with lactation. Postpartum decreases in the VLDL and LDL cholesterol/triglyceride ratio are seen at all lipoprotein concentrations independent of lactation. We conclude that triglyceride enriches VLDL at low concentrations and LDL at all concentrations in pregnancy and with oral contraceptive use, suggesting a common, hormonal mechanism. HDL is enriched with cholesterol during postpartum lactation, consistent with decreased transfer of cholesterol to other lipoproteins.(ABSTRACT TRUNCATED AT 250 WORDS)     

Low density lipoprotein receptor activity in freshly isolated human blood monocytes and lymphocytes

Circulating human monocytes and lymphocytes were isolated by counterflow and density gradient centrifugation. Binding and degradation of low density lipoprotein (LDL) occurred predominantly in monocytes and to a much lesser extent in lymphocytes. The findings are consistent with greater LDL receptor activity in freshly isolated monocytes than lymphocytes, in keeping with differences in other cell surface receptors between these two cell types. Therefore, when freshly isolated mixed mononuclear cells are used to study LDL receptor activity in vivo in humans, careful attention needs to be given to the proportions of monocytes and lymphocytes, or alternatively, relatively pure preparations of monocytes should be used.     

Comparative plasma catecholamine and hemodynamic responses to handgrip, cold pressor and supine bicycle exercise testing in normal subjects

Serial hemodynamic and plasma catecholamine responses were compared among 10 healthy men (27 +/- 3 years) (+/- 1 standard deviation) during symptom-limited handgrip (33% maximal voluntary contraction for 4.4 +/- 1.8 minutes), cold pressor testing (6 minutes) and symptom-limited supine bicycle exercise (22 +/- 5 minutes). Plasma catecholamine concentrations were measured by radioenzymatic assays: ejection fraction and changes in cardiac volumes were assessed by equilibrium radionuclide angiography. During maximal supine exercise, plasma norepinephrine and epinephrine concentrations increased three to six times more than during either symptom-limited handgrip or cold pressor testing. Additionally, increases in heart rate, systolic blood pressure, rate-pressure product, stroke volume, ejection fraction and cardiac output were significantly greater during bicycle exercise than during the other two tests. A decrease in ejection fraction of 0.05 units or more was common in young normal subjects during the first 2 minutes of cold pressor testing (6 of 10 subjects) or at symptom-limited handgrip (3 of 10), but never occurred during maximal supine bicycle exercise. The magnitude of hemodynamic changes with maximal supine bicycle exercise was greater, more consistent and associated with much higher sympathetic nervous system activation, making this a potentially more useful diagnostic stress than either handgrip exercise or cold pressor testing.     

A mucopolysaccharide storage disease with involvement of the renal glomerular epithelium

A young child with severe mental retardation, skeletal abnormalities and the phenotypic appearance typical of a mucopolysaccharide disorder was found to have a previously unrecognized form of mucopolysaccharide storage disease. Mucopolysaccharide was found to accumulate in perichondrium, coronary arteries, aorta and the glomerular epithelial cells of the kidney; the reticuloendothelial system remained free of mucopolysaccharide. Lipid accumulation was observed in peripheral neurons but not in central neurons. Skin fibroblast cultures accumulated ³⁵SO₄ to an extent intermediate between normal cell lines and those from patients with classic mucopolysaccharide storage disorders.     

Long-Term Follow-Up in Patients With Stable Angina and Unobstructed Coronary Arteries Undergoing Intracoronary Acetylcholine Testing

ObjectivesThe aim of this study was to investigate the prognosis of a large cohort of patients with stable angina and unobstructed coronaries undergoing acetylcholine spasm testing.BackgroundCoronary artery spasm can be found in up to 60% of patients with symptoms of myocardial ischemia despite unobstructed coronary arteries.MethodsConsecutive symptomatic patients with unobstructed coronary arteries undergoing acetylcholine testing to detect epicardial or microvascular coronary spasm were prospectively enrolled. After a median follow-up period of 7.2 years (6.5 to 7.9 years), data regarding mortality, nonfatal myocardial infarction, stroke, repeat coronary angiography, recurrent symptoms, and quality of life were obtained in 736 patients (57% women, mean age 62 ± 12 years).ResultsIn total, 55 deaths (7.5%), 8 nonfatal myocardial infarctions (1.4%), and 12 strokes (2.2%) occurred during the follow-up period. Recurrent symptoms were reported by 64% of patients, and repeat coronary angiography was performed in 12% of cases. Multivariate analysis revealed epicardial spasm as a predictor of nonfatal myocardial infarction (hazard ratio: 14.469; 95% confidence interval: 1.735 to 120.646) and repeat angiography (hazard ratio: 1.703; 95% confidence interval: 1.062 to 2.732), whereas patients with microvascular spasm more often had recurrent angina at follow-up (hazard ratio: 1.311; 95% confidence interval: 1.013 to 1.697).ConclusionsIn this long-term follow-up study, the overall prognosis of patients with coronary spasm was favorable. Patients with epicardial spasm were at increased risk for myocardial infarction and repeat angiography, while microvascular spasm was associated with recurrent angina. Acetylcholine testing may help identify patients at increased risk for adverse cardiac events among this overall low-risk population.     

Myocardial imaging with thallium-201: a multicenter study in patients with angina pectoris or acute myocardial infarction

A multicenter study of rest and exercise thallium-201 myocardial imaging in 190 patients from five centers was performed. Exercise images were obtained after graded treadmill or bicycle stress with use of five different gamma camera models and were interpreted by the originating investigator without knowledge of other clinical data. Of 42 patients with less than 50 percent coronary stenosis, 4 (10 percent) had a resting image defect, 1 (2 percent) a new exercise defect and 5 (12 percent) either a resting or an exercise image defect, or both. Of 148 patients with coronary stenosis of 50 percent or greater, 64, (45 percent) had an image defect in the study at rest, 90 (61 percent) had new or increased defects after exercise, and 115 (78 percent) had resting or exercise defects, or both. New exercise image defects were more common than exercise S-T depression (90 of 148 [61 percent] versus 62 of 148[42 percent]; P less than 0.01). In a second group of 111 patients with acute myocardial infarction studied at three centers, 90 patients (81 percent) had image defects compared with 71 (64 percent) two had new electrocardiographic Q waves (P less than 0.01). Smaller infractions, as assessed with serum enzyme values, and diaphragmatic infarctions were less commonly detected than larger or anterior infarctions. These findings suggest that myocardial imaging complements the electrocardiographic identification of acute myocardial infarction of exericse-induced myocardial ischemia.