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Biomedical subjects

M Apfelbaum

Publications and source records attributed to M Apfelbaum.

At least 109 records · Page 6Linked to original sources
PubMed1981

Carbohydrate intake affects insulin binding to human erythrocytes in normal weight subjects but not in subjects with family obesity.

The effects of different carbohydrate intakes on insulin binding to human erythrocytes were studied in thirty nine obese and twelve normal weight subjects belonging to twelve families with a strong penetrance of obesity("family experiment"), and in nine normal weight subjects with no family or personal history of obesity or diabetes ("diet experiment"). In the "family experiment," the mean insulin binding in obese subjects was significantly lower than in control normal weight siblings and parents. This difference cannot be related to an increase in carbohydrate or caloric intakes, since there was no difference in daily food intake between the obese and the control subjects. In the "diet experiment," the volunteers were studied four times: twice with their spontaneous diet, one with a normocaloric carbohydrate rich diet and once with a normocaloric fat rich diet. Both the carbohydrate and fat rich diets resulted in a significant lowering of binding when compared to the period of spontaneous diet. In the two experiments, the decrease in binding is due to a decrease in the number of receptors per erythrocyte. The possibility of a common underlying mechanism is discussed.

Adult↗
PubMed1981

Naltrexone suppresses hyperphagia induced in the rat by a highly palatable diet.

A highly palatable diet (ordinary chow supplemented with 4 highly palatable items changes every day) (HPD) provokes hyperphagia and overweight in the rat. After 17 weeks of such a diet, naltrexone (0.5 or 2.5 mg/kg IP) and opiate antagonist, was injected at the beginning of the dark period, and a food intake test was performed during the 3 following hours. Naltrexone does not modify the energy intake in control rats receiving ordinary chow but suppresses HPD induced hyperphagia. The involvement of the beta-endorphin system in this type of hyperphagia is discussed.

Animals↗
PubMed1981

Effects of a high protein very-low-energy diet on ambulatory subjects with special reference to nitrogen balance.

Forty young healthy ambulatory volunteers were given a very-low-energy diet (2.34 MJ, 560 kcal) containing 70 g of proteins of good biological value, 36 g carbohydrates, 2 g potassium, 0.5 g sodium, polyvitamins and 21 water. The nitrogen balance reached equilibrium on the 8th day. No risk factors were found. These results were compared with 4000 cases collected over 12 years. The latter were given a protein diet with neither salt nor carbohydrates. The addition of salts and carbohydrates resulted only in an increase of the subjects' comfort. The analysis of deaths occurring in the U.S.A. after protein diets lead to the conclusion that these very probably linked to the duration of the protein diet, the poor biological value of proteins provided, the insufficiency in potassium intake. The conditions for a safe use of a very-low-energy diet, are a large intake of proteins of good biological value, a large intake of potassium and probably small intake of carbohydrates and sodium.

Adolescent↗
PubMed1981

Effects of very restrictive high-protein diets with special reference to the nitrogen balance.

Since the introduction of restrictive hig protein diets in 1967, systematic studies have focused on the conditions necessary to reach an equilibrium of the nitrogen balance. These conditions appear to be: an intake of at least 55 g for women (75 g for men) of proteins of good biological value; an intake of about 1 g of potassium; more than 1.5 1 of water. Such a diet results in a decrease in energy expenditure at rest and during moderate physical effort, but not during maximal or submaximal efforts. The author does not prescribe this diet for more than three consecutive weeks.

Body Weight↗
PubMed1979

Circadian and ultradian rhythms in the feeding behaviour and nutrient intakes of oil refinery operators with shift-work every 3--4 days.

Seven healthy adult men, five shift-workers and two non-shift-workers (from 21 to 36 years; mean = 26.4) volunteered to record what and when they ate, both at work and at home, every day, during eight consecutive weeks (Oct. - Dec. 1974). 1) All the subjects maintained the timing of main-meal (lunch and supper) during all shifts. 2) The major intake of protein and lipid was concentrated on the two main meals during all shifts. 3) Only the pattern of carbohydrate intake was modified by the shift-work: e.g. night-shift is associated with nibbling behaviour. 4) However, shift-work and in particular the occurence of nibbling behaviour did not result in change either in the mean 24 h caloric intake, or in the percentage of protein calories. 5) The comparison between the constancy of the timing of major meals and the shift of the timing of circadian rhythm acrophases of the 5 shift-workers leads to conclude that meal timing had a poor synchronizing effect, if any.

Adult↗
PubMed1978

Beta-adrenergic receptors and myogenesis.

The rat myogenic cell line, L8, contains a beta-adrenergic catecholamine-sensitive adenylate cyclase. Prior to cell fusion, and continuing thereafter, beta-adrenergic sites, as determined by the stereospecific binding of (125I)-hydroxybenqylpindolol, I1(125I)IHYP] increases from 470 to 2000 sites/cell. There is also an increase in adenylate cyclase (2-5 fold) and endogenous cAMP (5-30 fold) following stimulation by catecholamine. The dissociation constant (KD) of (125I)IHYP for unfused and fused cell-homogenates, as determined by estimation with Scatchard analysis, by direct determination at receptor concentrations well below the KD, or by association (4.6 X 10(8) M-1 min-1); and dissociation (0.028 min-1) kinetics; ranged from about 40 to 70 pM. The acquisition of beta-receptors prior to fusion in L8 cells may implicate this system in the regulation of myogenesis.

Adenylyl Cyclases↗
PubMed1977

Effects of severe diet restriction on the oxygen consumption of obese women during exercise.

Eleven moderately obese, but otherwise healthy, young women were studied for three days while being fed their normal, unrestricted diet and then again for a two week period while being fed an energy-restricted, high-protein diet--220 kcal (0.92 MJ)/day as casein. Oxygen consumption (VO2) was measured 32 times for each subject, both at rest and during bicycle exercises. For each subject oxygen consumption was significantly lower, at rest and during moderate exercise, when the subjects were being fed the restricted diet. There was no significant difference among the diet treatments at the highest activity levels. The explanation proposed (though without experimental proof) is that, during the restricted diet, the increased reverse triiodothyronine (rT3) would result in a decrease of the aerobic glycolysis and no change in the anaerobic glycolysis.

Adult↗
PubMed1977

Weight and metabolic changes induced by low carbohydrate-high fat diets in man and in rat.

Weight loss and potential toxicity of low carbohydrate-high fat diets were examined in 8 volunteer medical students given either a high fat diet or a high carbohydrate diet for 15 days, as well as in 36 Sprague-Dawley rats fed for 5 weeks a series of low carbohydrate diets (less than 1%), varying in protein and lipid proportions. A weight loss occurred with the low carbohydrate-high fat diets; serum cholesterol level increased in both man and rat; plasma triglycerides rose in man. In rat, we found an increase in hepatic lipid levels as in plasma ketone and non-esterified fatty acid concentrations. These effects seemed to be related to the increase in lipid intake rather than the lack of carbohydrates.

Adipose Tissue↗