Alfredo Lopez-S

Effect of exercise and physical fitness on serum lipids and lipoproteins

Abstract The effect of physical exercise on serum lipids and lipoproteins was studied in 13 young medical students participating in a exercising program of four daily 30 min sessions of intense physical exercise per week. After seven weeks of exercise a signific ant decrease was observed in serum triglycerides (from 110 to 80 mg/ 100 ml) and pre-β-lipoproteins (from 93 to 54 mg/100 ml) with more moderate effect on serum cholesterol, β- plus pre-β-lipoprotein cholesterol and β-lipoprotein. A concomitant increase in α-lipoprotein values was also observed (from 286 mg/100 ml to 332 mg/100 ml). A weak negative correlation was observed in 100 young individuals participating in a Nutrition Survey between the degree of physical fitness as measured by the Harvard Step Test and serum cholesterol levels. The contradictory reports on the effect of exercise upon serum lipids, mainly cholesterol, might be explained by the effect of exercise on lipoprotein metabolism.

Complexing of serum pre-β- and β-lipoproteins and acid mucopolysaccharides

Serum pre-/3and /3-lipoproteins were observed to form insoluble complexes with sulfated acid mucopolysaccharides (MPS) in presence of Gas+. Optimum conditions for the formation of the complexes were investigated with varying amounts of MPS and Caa+, and the degree of complexing of various MPS was studied. Heparin, even at low concentrations, formed maximum amounts of complexes. These lipoprotein-heparin complexes were extensively analyzed by several analytical and different electrophoretic methods, including electrophoresis on agar-agarose gel. The complexes precipitated with heparin demonstrated a mixture of pre-/Iand /&lipoproteins, and critical amounts of Gas+ were found essential for the formation of complexes. A mechanism of formation of a complex through Caz+, acting as a bridge between N-sulfate groups of heparin and phosphate groups of phospholipids of pre-/3and /3-lipoproteins, was suggested.

Total serum cholesterol and urinary dehydroepiandrosterone in humans

The relationship between urinary excretion of dehydroepiandrosterone (DHEA) and total serum cholesterol was evaluated in an epidemiological study of coronary risk factors. The results of this study show statistically significant negative correlation (r = -0.238; P -0.014) between the urinary excretion of DHEA (mg/g creatinine) and total serum cholesterol. Total serum cholesterol (r = 0.278) and to a lesser extent. DHEA (R = 0.021) were found to be correlated with age. However, it was determined that the correlation between serum cholesterol and urinary DHEA was not attributable to the effect of age, since the partial correlation coefficient between serum cholesterol and urinary DHEA adjusted for age (r = 0.240) was found to be statistically significant (P less than 0.05). Negative but non-significant correlations were also found between urinary excretion of DHEA and many of the accepted risk factors for coronary heart disease.

Metabolic effects of exercise. I. Effect of exercise on serum lipids and lipogenesis in rats.

Summary To evaluate the metabolic effects of exercise, three groups of exercised male rats were compared to their sedentary controls at the end of 10 wk of voluntary exercise in rodent activity cages. Exercised rats consumed more food than sedentary rats but had greater weight gain only at the higher levels of activity. Exercised rats had significantly lower serum triglycerides and higher values of adipose tissue α-glycero-phosphate dehydrogenase activity. At higher levels of physical activity, the exercised rats exhibited larger adrenal glands and lower values of hepatic glucose-6-phosphate dehydrogenase. It is concluded that specific levels of voluntary exercise are needed to achieve specific metabolic effects.

A Simplified Technique for Semiquantitative, Clinical Estimation of Serum β-and Pre-β-Lipoproteins

An important relationship exists between abnormalities of serum lipoproteins and atherosclerosis. A simple and reproducible system for a semiquantitative serum lipoprotein analysis is described and th

A case-control study of serum vitamins A, E, and C in lung cancer patients.

In a case-control study, serum levels of vitamins E, C, and A, carotenoids, total cholesterol, and retinol-binding protein along with smoking levels were studied on 59 persons newly diagnosed with lung cancer and also on matched hospitalized controls. The relative risk for smoking increased with the number of pack years of cigarettes smoked. Cases had significantly lower serum levels of carotenoids, vitamin E, and total cholesterol. Adjustment for serum cholesterol levels diminished the case-control difference for serum carotenoid levels and reduced the case-control difference for serum vitamin E levels. The results indicate that serum vitamin E may also be associated with lung cancer, possibly to a greater degree than serum retinol (vitamin A) is associated with lung cancer.

Effect of Exercise on Serum Lipids and Lipoproteins

The available literature on the effect of exercise on serum lipids and lipoproteins is relatively scarce, often controversial, and, as a whole, inconclusive.

Metabolic effects of exercise. II. Residual metabolic effects of exercise in rats.

Summary This report describes the duration of changes in serum lipids, adrenal weight and hepatic G-6-PD activity in rats following the termination of 10 weeks of voluntary activity in a revolving drum. Exercised rats had lower weight gain, larger adrenal glands, lower serum cholesterol, lower serum triglycerides and lower liver glucoses-phosphate dehydrogenase (G-6-PD) activity than the sedentary controls. The differences between exercise and control rats in adrenal gland weight, body weight and G-6-PD tend to disappear within 3 wk after termination of the exercise. These experiments provide evidence that exercise can affect lipid metabolism and have a beneficial effect on the lowering of serum lipids. It also shows that this effect will persist for up to 3 wk after the exercise is terminated, under the experimental conditions of this study. The authors greatly acknowledge the technical assistance of Mrs. Lillie Bell.

Serum lipid transport systems: recent advances.

Lipids circulating in the plasma are transported in water soluble form as lipid-protein complexes. Lipoproteins can be classified according to size, density, electrophoretic mobility and protein composition. The ability of low density lipoproteins and very low density lipoproteins (VLDL) to form complexes with different polyanions has been also used as a method for separation and study of serum lipoproteins. Even within classes of lipoproteins closely related otherwise, the amount of different lipids and their ratios to each other and to protein are variable. Two enzymatic systems seem to be at least partly responsible for the different lipid compositions of serum lipoproteins: lipoprotein lipase and lecithin-cholesterol acyltransferase (LCAT). LCAT, which seems to be associated with α-lipoproteins, is responsible for the formation of the bulk of cholesteryl-esters in human serum. Changes in activity of this enzyme may explain the observed changes with age and disease of serum cholesteryl-ester fatty acids (CEFA). Differences in CEFA pattern are found between newborn and adult animals, including man. The activity of serum LCAT was observed to increase with age in animals and to decrease markedly in patients with liver cirrhosis. These patients show abnormal serum CEFA patterns and abnormally low proportions of pre-β- (VLDL) and α- (high density) lipoproteins.

Nutrition and cancer: A curriculum and short student research experiences

In 1988, Louisiana State University Health Sciences Center (LSUHSC) received an NCI/NIH R25 grant to strengthen nutrition-cancer education in the medical school and to provide short cancer-related research experiences for students. Support for the nutrition-cancer curriculum component of the grant was limited to the first five years, while renewal of the research component was possible on a competitive basis. After the initial five-year award ended, the administration of LSUHSC assumed the support of the nutrition-cancer curriculum. This curriculum, modified over time, continues to be taught in each year of medical school and culminates with a required clinical nutrition course in the fourth year. The teaching of nutrition continues to be very successful and is well received by students and faculty. The research component, renewed twice, has achieved its goals over the same period. As a consequence of the initial award and the commitment of the administration, nutrition education at LSUHSC remains strong and is well established.