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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Postabsorptive plasma amino acid and insulin concentrations were determined in subjects with hyperplastic obesity and in nonobese controls before and after a 6-wk period of physical training. After the training period the plasma concentrations of insulin and leucine decreased and the concentration of alanine increased in the obese subjects. No changes were noticed in the controls. The obese subjects had elevated plasma levels of valine, isoleucine, leucine, tyrosine, and phenylalanine before as well as after physical training. The concentrations of these amino acids were correlated to the plasma insulin level and to lean body mass before but only to lean body mass after physical training. It is suggested that the lean body mass, whick is higher in hyperplastic obesity, contributes to the elevated concentrations of amino acids, and it is unlikely that the insulin decreases in the obese subjects after physical training is mediated through an effect of amino acids on insulin secretion.
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PMID:Effects of physical training and lean body mass of plasma amino acids in man. 68 Dec 2

Rates of absorption of leucine, glycylleucine, and glucose, and rates of hydrolysis of maltose were determined in the jejunum of a group of obese persons before and at intervals (between 2 and 20 montsh) after jejunoileal bypass for the treatment of obesity. The leucine absorption rate was significantly reduced after the bypass, but the absorption rates of glycylleucine and glucose as well as the hydrolysis rate of maltose were unchanged. Light microscopic investigation of the jejunal mucosa, obtained by a peroral biopsy technique before and at 7 months after by bypass operation, did not reveal any change in the histological appearance of this tissue. The plasma aminograms of all 7 patients were compared before and at intervals after the bypass operation; all exhibited a constant pattern of change that was characterized by significant decreases in the concentrations of serine and glycine and by significant decreases in the concentrations of valine, isoleucine, leucine, tyrosine, and phenylalanine. This pattern of change, which is characteristic of protein depletion, persisted during the entire period of observation. Two of these 7 patients developed laboratory evidence of hepatic dysfunction. It is concluded that (1) protein depletion is common to all patients with jejunoileal bypass with or without hepatic dysfunction; and (2) protein depletion results in a sustained reduction in free amino acid absorption in the jejunum.
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PMID:Absorptive and digestive function of the jejunum after jejunoileal bypass for treatment of human obesity. 96 65

Long term feeding of a sucrose rich diet to rats is accompanied by a decreased glucose assimilation rate, despite high plasma insulin levels. Hyperinsulinism is at least partially based on a relative obesity, with increased amounts of abdominal- and retroperitoneal fat tissue, but unchanged total body weight compared to starch fed controls. The secretory pattern of insulin release was studied following glucose, arginine, fructose and sulfonylurea administration in the isolated perfused pancreas of sucrose and isocaloric starch fed rats. In addition, isolated islets of Langerhans were used to demonstrate the effects of glucose on insulin secretion and the incorporation of H-3 leucine into the proinsulin and insulin fraction of islet proteins. Following 11 mM glucose, the dynamics of insulin release in the isolated perfused pancreas of sucrose fed rats is characterized by a markedly elevated, late plateau-like response, usually seen only at higher glucose concentrations. Hyperinsulinism, as compared to starch fed controls, can also be demonstrated following arginine and the sulfonylurea HB-419, whereas fructose has no effect in the presence of low glucose concentrations. During incubation of the pancreatic islets, the hyperinsulinism in sucrose-, compared to starch fed rats, is more pronounced at 11 mM glucose than at 5.5 mM glucose. The incorporation of H-3 leucine into the proinsulin-insulin fraction of islet proteins in sucrose compared to starch fed rats, however, is significantly greater with glucose 5.5 mM than at high glucose level. In sucrose fed rats, secretion and biosynthesis of insulin thus appear to be elevated but closely linked only at physiological glucose concentration.
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PMID:Insulin secretion and biosynthesis in sucrose fed rats. 97 34

The fat cells of rat epididymal adipose tissue contain an average of 0.5 mg of cholesterol per gram of triglyceride. Of this cholesterol, 90% is nonesterified and 80% is located in the lipid storage compartment. The fat cell cholesterol content correlated positively with cell size. During fasting the free cholesterol of the adipocyte decreased in parallel with triglyceride, whereas the amount of esterified cholesterol did not change. The fat cell cholesterol content is independent of the amount of dietary cholesterol. On in vitro incubation of rat fat cells with radiolabeled acetate, mevalonate, glucose, leucine, or water, labeled cholesterol was synthesized. The rate of cholesterol synthesis increased with fat cell size. Fasting suppressed cholesterol synthesis by 90%, whereas refeeding stimulated the synthesis above values found in normally fed rats. Stimulation of lipolysis with theophylline or with dibutyryl cyclic AMP markedly inhibited cholesterol synthesis in fat cells. Insulin increased the incorporation of glucose and leucine into fat cell cholesterol. The cholesterol synthesis in fat cells was not suppressed by a high cholesterol diet. Addition of very low or low density lipoprotein into the incubation medium suppressed fat cell cholesterol synthesis whereas high density lipoprotein did not. The lipoprotein-free serum stimulated cholesterol synthesis compared with serum-free medium. The rate of cholesterol synthesis in total adipose tissue of rat was estimated to be 4% of that in the liver. It seems unlikely that the increased body cholesterol turnover present in obesity is accounted for by the enhanced cholesterol formation in the enlarged adipose tissue.
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PMID:Regulation of cholesterol synthesis and storage in fat cells. 112 58

The action of insulin (0.1 U/ml) on the metabolism of human intestinal smooth muscle was studied in vitro. The experiments were performed on the muscle layer of human jujunum obtained from patients undergoing intestinal shunt operations because of obesity. Insulin significantly increased glucose uptake, glycogen content, the membrane transport of alpha-amino-isobutyric acid (AIB), the incorporation of leucine into protein and tended to increase the membrane transport of the nonutilizable model monosaccharide 3-0-methylglucose. The effects of insulin were moderate and appeared after incubation times of 120 to 180 min.
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PMID:Effect of insulin on human intestinal smooth muscle. 118 19

In this study of spontaneous obesity of pigs, specific metabolic shifts were observed, which explain an increase in fat deposition. Liver tissue utilization of pyruvate and glucose for oxidation and lipogenesis showed no significant difference between lean and obese pigs. Adipose tissue utilization of glucose, acetate and glycerol for triglyceride and fatty acid synthesis was greater in obese pigs than lean pigs (P less than 0.01). No significant difference in leucine incorporation into lipid fractions was found. Of the substrates utilized, glucose supplied 86 and 94% of the glyceride-glycerol synthesized in lean and obese pigs, respectively. Glycerol was not a major contributor to glyceride-glycerol synthesis (3.5 to 5.5%), in spite of the presence of adipose tissue glycerokinase. An increase (P less than 0.05) in alanine incorporation into glucose was observed in liver tissue from obese pigs. In general, the levels of enzymes activities associated with gluconeogenesis, glycolysis, and lipogenesis supported the findings of in vitro utilization of these substrates.
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PMID:A comparison of the enzyme levels and the in vitro utilization of various substrates for lipogenesis in pair-fed lean and obese pigs. 125 Aug 52

The effects of cafeteria diet-induced obesity upon in vitro uptake of L-Alanine, Glycine, L-Lysine, L-Glutamine, L-Glutamic acid, L-Phenylalanine and L-Leucine by isolated rat erythrocytes have been studied. The total Phe and Leu uptakes followed Michaelis-Menten kinetics. The Glu uptake was fitted to diffusion kinetics. The uptakes of Ala, Gly, Lys and Gln were best explained by a two-component transport: one saturable and one diffusion. Obesity increased the Km value for Ala, Gln and Leu, and the Vmax value for Ala, but decreased the Vmax for Lys. Kinetic parameters of Phe uptake were unaffected by obesity. In addition, the pseudo-first order rate constant (Vmax/Km) for Ala, Gly, Gln, Lys and Leu uptake decreased as a result of cafeteria diet-induced obesity. The Kd value for Ala, Gly, Gln and Glu decreased and that of Lys increased as result of obesity. These adaptations could, at least in part, explain alterations in amino acid distribution between blood cells and plasma related to overfeeding or obesity.
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PMID:Effect of diet-induced obesity on kinetic parameters of amino acid uptake by rat erythrocytes. 148 91

Some previous studies have indicated that rates of proteolysis and protein synthesis are greater in obese than in lean subjects, whereas others have not supported this finding. In the present study, we have measured postabsorptive protein turnover in a large group (n = 24) of obese women to establish more conclusively whether obese women have higher rates of protein turnover than lean women (n = 12), and to determine whether obese subjects with the greatest abdominal fat accumulation or those with the most severe insulin resistance (as determined by oral glucose tolerance testing) have the highest rates of protein turnover. Leucine appearance rate (Ra) was used as an index of whole-body proteolysis, and the fraction of Ra not oxidized was used as an index of whole-body protein synthesis. Leu Ra, oxidation, and incorporation into protein after an overnight fast were approximately 25% greater in obese than in lean women, and were approximately 10% to 15% greater after dividing by lean body mass (LBM) or adjusting for LBM by analysis of covariance. Among obese women, the degree of obesity (over the range of 30% to 47% fat) was not a significant determinant of protein turnover, nor were degree of insulin resistance, visceral fat accumulation (determined by magnetic resonance imaging [MRI]), or subcutaneous abdominal fat accumulation (also determined by MRI). However, the women with the highest rates of protein turnover also had higher waist to hip circumference ratios (WHR). We conclude that even moderate obesity is associated with increased protein turnover, and that this effect is not completely explained by the higher LBM in obese subjects.
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PMID:Increased protein turnover in obese women. 151 19

1. To compare the impact of type of carbohydrate, genotype and phenotype on the synthesis and levels of plasma lipoprotein protein. Sprague-Dawley rats and carbohydrate-sensitive LA/N-corpulent (cp) rats were fasted (2 days) and then fed diets containing 54% carbohydrate as either sucrose, fructose or cooked cornstarch for 2 days. 2. The amount of 3H-protein present in the VLDL + chylomicron fraction of Sprague-Dawley rats 2 hr after injection of 3H-leucine was affected by type of dietary carbohydrate: sucrose greater than fructose greater than starch. 3. Obese and lean LA/N-cp rats fed diets containing sucrose or fructose had lower concentrations of HDL protein and higher levels of 3H-protein in VLDL + chylomicron fraction than those fed starch. 4. Obese LA/N-cp rats had more HDL protein and higher levels of 3H-protein in VLDL + chylomicron fraction than their lean littermates.
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PMID:Lipoprotein status in Sprague-Dawley and LA/N-corpulent rats as affected by dietary carbohydrates. 167 96

To examine whether moderate obesity and differences in body fat distribution are associated with abnormalities of protein metabolism, leucine turnover was measured in three groups of age-matched premenopausal women. Ten upper-body-obese (UB Ob), 10 lower-body-obese (LB Ob), and 10 nonobese (Non Ob) women were studied in an overnight postabsorptive condition (basal) and again during an infusion of low physiologic amounts of insulin (insulin clamp). Results showed that basal leucine carbon flux was greater (P less than 0.05) in UB Ob and LB Ob women than in Non Ob women (2.96 +/- 0.08 vs 3.14 +/- 0.16 vs 2.68 +/- 0.08 mumol.kg lean body mass-1.min-1, respectively; mean +/- SEM). Leucine carbon flux was not suppressed during the insulin-clamp study in UB Ob women but was in the LB Ob and Non Ob women. We conclude that moderate obesity is associated with increased proteolysis and that insulin's antiproteolytic actions are impaired in upper-body obesity. These findings could have implications for future studies of and treatment of obesity.
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PMID:Protein metabolism in obesity: effects of body fat distribution and hyperinsulinemia on leucine turnover. 198 43


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