Medical students' knowledge, attitudes, and behavior concerning diet and heart disease

Demand for physician-based dietary treatment of hypercholesterolemia is increasing, but medical care providers feel that they lack the skills and confidence necessary to provide these services. Using a self-administered questionnaire, we studied the relationships among dietary knowledge, attitudes, and behaviors to identify the educational needs of entering medical students. On average, dietary behavior and background knowledge of the diet-coronary heart disease association compared favorably to national dietary recommendations and knowledge of the U.S. public. However, practical knowledge necessary for diet counseling was weak, and attitudes about the "prudent" diet were poor. More favorable attitude scores were associated with healthier eating habits, while greater knowledge was not. Our results suggest that entering medical students already have a basic understanding of the diet-heart disease link, which is covered in the curricula of most medical schools. Medical education should include more emphasis on practical dietary knowledge and improving attitudes about the prudent diet.

Stimulation of glucose analogue uptake by cerebral microvessel endothelial cells by a product released by astrocytes

Astroglial cells, both normal and neoplastic, secreted a product that stimulated glucose uptake by cerebral microvessel endothelial cells by 23% and 50%, respectively. Neither cerebral microvessel smooth muscle cells nor oligodendrocytes affected endothelial cell glucose uptake. The astrocytic product(s) did not affect glucose uptake by aortic endothelial cells. The effect on the cerebral microvessel endothelial cells increased with increasing time of exposure of the cells to the astroglial product(s), and required the constant presence of the astrocytic product to be maintained. The presence of a protein synthesis inhibitor during endothelial cell exposure to the astroglial conditioned medium blocked the stimulation of glucose uptake. Treatment of the astrocytic product with a protease destroyed its effectiveness. These results support the hypothesis that astrocytes induce the expression of at least one blood-brain barrier property by the cerebral microvasculature, and suggest that this induction may be produced by a protein released by the astrocytes.

Induction of gamma-glutamyl transpeptidase in cultured cerebral endothelial cells by a product released by astrocytes

gamma-Glutamyl transpeptidase (gamma GTP) is an enzyme found in cerebral capillary endothelial cells, the presumed site of the blood-brain barrier, but not in endothelial cells lining blood vessels in other parts of the body. Using a line of mouse cerebral microvessel endothelial cells (ME-ly cells) and a sensitive colorimetric assay to measure gamma GTP levels we demonstrated that primary cultures of mouse astrocytes and a line of rat C6 glioma cells released a soluble product(s) that induced the production of gamma GTP in cultured endothelial cells by 34% and 39%, respectively, over control levels. Cerebrovascular smooth muscle cells had no significant effect on gamma GTP levels in ME-ly cells, and the astrocyte product(s) had no effect on rabbit aortic endothelial cells. The induction of gamma GTP levels in ME-ly cells was apparent after one day of exposure to the astrocyte product(s) and increased in magnitude with increasing time of exposure of the ME-ly cells to the product(s). Removal of the product(s) from the ME-ly cells resulted in a return to control levels of gamma GTP in the ME-ly cells within 2 days. The presence of a protein synthesis inhibitor during incubation with the product(s) blocked the induction of gamma GTP in ME-ly cells, and treatment of the product(s) with 200 U/ml TPCK-trypsin destroyed its inductive properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of hypertension in pregnancy with methyldopa: a randomized double blind study

Twenty-five patients whose pregnancies were complicated by chronic hypertension were entered in a double-blind study and randomly allocated to treatment with methyldopa (Aldomet) or placebo. Thirteen patients were in the treatment group and 12 in the placebo group. The two groups showed no significant difference in demographic and pretreatment laboratory profiles. Methyldopa-treated patients registering in the first trimester had a significant reduction in the mean arterial pressure (MAP) during the second and third trimesters (P less than 0.025). No significant differences in birth weight (BW), ponderal index (PI) were found when results were corrected for gestational age (GA), race, and sex. The mean GA was significantly prolonged in the methyldopa-treated group by 10.3 days (P less than 0.05). The frequency of superimposed pre-eclampsia was similar in both groups (33.3% vs. 38.4%). However, 75% of the superimposed pre-eclampsia occurred antepartum in the placebo group, while 80% of the methyldopa-treated group developed superimposed pre-eclampsia intrapartum. The results of this small study suggest that the treatment of hypertension in pregnancy may reduce MAP and possibly delay the occurrence of superimposed pre-eclampsia and thus afford a prolongation of the pregnancy.

Effect of inorganic lead on some functions of the cerebral microvessel endothelium

The effect of inorganic lead on two functions of cerebral microvessel endothelium, cell division and glucose analog uptake, was investigated. Lead concentrations considered to be toxic in humans inhibited both functions in cultured endothelial cells. Both effects were dependent on the length of lead exposure and dose over the range of 10(-4) to 10(-6) M lead acetate. After 4 days of exposure there were 76% fewer cells in 10(-4) M lead-exposed cultures relative to control cultures. After 4 days of exposure to 10(-5) M lead there were 55% fewer cells, and after 10(-6) M lead exposure there were 15% fewer cells. Two days after 10(-4) M lead exposure [methyl-3H]thymidine incorporation into endothelial cells was inhibited by 71%. Incorporation was inhibited 47% by 10(-5) M lead but 10(-6) M lead did not inhibit incorporation after 2 days of exposure. Glucose analog uptake was inhibited in both contact-inhibited and log-phase cells; however, the latter were more sensitive to lead and this increased sensitivity correlated with a higher lead content in this cell population. Both the specific carrier-mediated and the nonspecific components of glucose analog uptake were inhibited by exposure of the endothelial cells to lead. A lead exposure of 40 min produced a significant effect on the uptake mechanism. In order to manifest its effects the lead had to be present in serum-containing medium, suggesting that some serum component was necessary to present the lead to the endothelial cells. These findings imply that the initial target of inorganic lead in the CNS may be the plasma membrane of the capillary endothelial cells, and that lead may act by altering the physiological function of these membranes.

Insulin stimulates DNA synthesis in cerebral microvessel endothelium and smooth muscle

Experiments were performed to test the hypothesis that insulin stimulates DNA synthesis in cerebral microvessel endothelium and smooth muscle. Cultured endothelium and smooth muscle derived from isolated mouse cerebral microvessels were exposed to insulin in serum-free medium, and [3H]-thymidine incorporation in the cells was measured. Up to 40-fold stimulation of DNA synthesis in endothelium and fourfold stimulation in smooth muscle were observed. Stimulation became maximal in both cell types at an insulin concentration of approximately 10(4) ng/ml, although an effect was observed at much lower concentrations. Similar concentrations of insulin produced a less-dramatic (approximately twofold) increase in both endothelial and smooth muscle cell numbers. This effect of insulin, observed in microvessel endothelium and smooth muscle, but not in bovine aortic endothelium, emphasizes another way in which large- and small-vessel endothelia appear to differ.

Uptake of glucose analogues into cultured cerebral microvessel endothelium

Tritiated glucose analogues 3-O-methylglucose (3-OMG) and 2-deoxyglucose (2-DG) were used to study glucose uptake properties in established lines of cultured mouse cerebral microvessel endothelium. Uptake of both analogues was similar in terms of rate and absolute amount for the first two minutes. Thereafter, intracellular accumulation of 2-DG continued at a more rapid rate because of intracellular phosphorylation of this substrate. The uptake of 3-OMG uptake was temperature-dependent, independent of Na+, and not inhibited by ouabain or 2,4-dinitrophenol. Phloretin and cytochalasin B both significantly inhibited 3-OMG uptake. Other hexoses in high concentration acted as competitive inhibitors at the endothelial cell membrane. Pre-incubation of cells with 50 mM D-glucose resulted in higher levels of 3-OMG accumulation than in control cells (counter-transport phenomenon). In contrast to findings at the blood-brain barrier in vivo, insulin was found to stimulate 3-OMG uptake. Maximal stimulation of approximately 3-fold was found at ambient insulin concentrations of 1,000 ng/ml or higher. The findings provide support at the cellular level for some components of the model of carrier-mediated glucose transport across the blood-brain barrier which has been postulated to exist in vivo. The effect of insulin is discussed in the light of new data that show stimulation of glucose analogue transport into isolated cerebral capillaries.

Effects of prazosin on forearm resistance and capacitance vessels

The effects of oral prazosin on the peripheral circulation were evaluated in 10 subjects, including 7 patients with chronic congestive failure due to coronary heart disease. To achieve this purpose the actions of 30 to 50 micrograms/kg body weight prazosin were assessed on both the forearm arteriolar and venous beds simultaneously with the use of the limb plethysmographic technique. Prazosin produced marked decline of forearm venous tone (FVT) from 44.5 +/- 12.3 to 14.3 +/- 3.1 mm Hg/ml (p less than 0.01) concomitant with marked decrease in forearm vascular resistance (FVR) from 70.2 +/- 11.4 to 48.4 +/- 4.9 mm Hg/ml/100 gm/min (p less than 0.05) which persisted for at least 60 mins without change in heart rate. These findings, demonstrating that prazosin induces systemic venodilation and peripheral arteriolodilation, indicate potential benefits of the oral drug for relief of pulmonary congestion and elevations of cardiac output in patients with chronic congestive heart failure.