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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

Insulin resistance is frequently associated with acanthosis nigricans and hyperandrogenism. In patients with type A insulin resistance, this has been shown to be due to genetic defects in insulin receptor function. However, other patients with a similar clinical syndrome have been reported to have a variant of this syndrome, in which assays of insulin receptor function were normal. We have sequenced a portion of the insulin receptor gene in one such patient, a 29-yr-old woman with obesity and insulin resistance. The patient is heterozygous for a mutation substituting isoleucine for methionine at position 1153. Met1153 is located in the intracellular domain of the receptor near the cluster of tyrosine phosphorylation sites at positions 1158, 1162, and 1163. Studies of the mutant receptor expressed in NIH-3T3 cells demonstrated that the Ile1153-mutation impairs the ability of insulin to stimulate autophosphorylation of solubilized insulin receptors. In addition, the mutation impairs the ability of insulin to stimulate receptor tyrosine kinase activity to phosphorylate an artificial substrate [poly(Glu-Tyr)]. It seems likely that this defect in receptor tyrosine kinase activity explains the defect in the ability of the patient's insulin receptors to mediate insulin action in vivo. Furthermore, this patient provides a paradigm in which genetic factors act in concert with other risk factors, such as obesity, to cause clinically important insulin resistance.
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PMID:A mutation in the tyrosine kinase domain of the insulin receptor associated with insulin resistance in an obese woman. 189 Jan 61

Obesity is a major nutritional disorder that produces many abnormal metabolic responses. The effect of injury-induced stresses acting synergistically with the state of excessive body fat is not well known. Plasma levels of circulating free amino acids reflect the net status of protein breakdown and utilization. Hypoaminoacidemia is a common finding in severe injury and its significance in obese subjects was investigated. We measured in 10 obese (body mass index [BMI] greater than 30) and 10 non-obese (BMI less than 30) traumatized (Injury Severity Score [ISS] 17 to 50) patients, the plasma levels of free amino acids in the early "flow" phase of injury when subjects were receiving maintenance fluids without calories or nitrogen. Postabsorptive control samples were obtained from 10 obese and 10 non-obese volunteers. Obese controls showed an increase in valine, leucine, isoleucine, and glutamic acid levels, and a decrease in glycine, tryptophan, threonine, histidine, taurine, citrulline, and cystine levels compared with lean controls. Hypoaminoacidemia was equally seen in traumatized obese and non-obese patients, and it was mainly due to a 24% decrease in nonessential amino acids. Remarkably, essential amino acid levels were the same in all groups. Arginine and ornithine levels were significantly different in traumatized obese compared with non-obese patients. The hypoglycinemia seen in non-obese trauma patients was absent in obese patients. The changes in levels of sulphur-containing amino acids also suggest that monitoring of these levels should be included in the nutritional management of obese trauma patients.
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PMID:Altered plasma free amino acid levels in obese traumatized man. 201 Oct 79

Twenty obese and 20 lean LA/N-cp male rats and 20 male Sprague-Dawley rats were fed a diet containing either 54 percent sucrose or starch for six weeks. After a 14-16 hour fast, rats were killed. Liver and kidney enzyme activities were determined in the LA/N-cp rats while plasma urea and selected amino acids were determined in all rats. Liver glucose-6-phosphatase (G6PASE), fructose-1,6-bisphosphatase (FBPASE), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), malic enzyme (ME), glucokinase (GK), pyruvate kinase (PK), phosphofructokinase (PFK), glutamic-oxaloacetic-transaminase (GOT), glutamic-pyruvic transaminase (GPT), arginase (ARGASE), arginine-synthase (ARG-SYN) and ornithine transcarbamylase (OTC) levels were significantly affected by phenotype (obese greater than lean). All the above changes in enzyme levels were exaggerated by sucrose-feeding with the exception of PK, PFK, GOT, GPT, ARGASE and ARG-SYN. Kidney cortex G6PASE, PEPCK and ARGASE activities were higher in the obese rats as compared to the lean littermates. Sucrose feeding resulted in higher cortex G6PASE, FBPASE and PEPCK as compared to starch-fed rats. A phenotype effect was noted with plasma glutamate, urea, leucine, isoleucine and valine (obese greater than lean) and a diet effect was seen with aspartate, phenylalanine, leucine and valine (sucrose greater than starch) concentration. Sprague-Dawley rats had higher plasma urea and lower alanine than lean LA/N-cp males. Metabolic obesity in the LA/N-cp rat appears to involve an elevated capacity for pathways of glycolysis, gluconeogensis, lipogenesis and amino acid catabolism in the liver.
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PMID:Effect of dietary carbohydrate on liver and kidney enzyme activities and plasma amino acids in the LA/N-cp rat. 204 12

The purpose of this study was to determine if the metabolic response to obesity and to pair feeding of obese Zucker rats to lean Zucker rats was similar across skeletal muscles. Oxidation of glucose, palmitate and isoleucine was studied in muscle strips in vitro using appropriate 14- carbon substrates as tracers. The plantaris muscle was subjected to histochemical analyses using an alkaline actomyosin ATPase, NADH-tetrazolium reductase and an oil red 0 stain. Soleus muscles from both ad libitum and pair fed obese rats oxidized less glucose to CO2, but released similar amounts of lactate when compared to the soleus muscles of lean rats. Oxidation of glucose was similar in the extensor digitorum longus (EDL) muscle of ad libitum fed obese rats, but lower when pair fed to the intake of lean rats. No differences were apparent in palmitate oxidation to CO2 or in incorporation into lipid (both soleus and EDL muscles), except in the EDL muscle of pair-fed obese rats which exhibited a higher rate for palmitate metabolism when compared with lean rats. Isoleucine oxidation to CO2 was higher in the EDL and plantaris muscles, but similar in the soleus muscle of ad libitum-fed obese rats when compared with lean rats. The magnitude of the difference in isoleucine oxidation was similar when the obese rats were pair fed. No differences in the percentage of plantaris muscle fibers sensitive to alkaline ATPase staining were observed. The plantaris muscle of obese rats, contained a higher proportion of oxidative fibers. These results indicate the great risk in generalizing about metabolic activity of the whole skeletal muscle mass based on observations made on one, or even two, distinct muscles in this animal model. Also, pair feeding of obese to lean Zucker rats did not result in uniform changes in metabolism between muscles of the obese rats.
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PMID:Metabolic characteristics of skeletal muscle from lean and obese Zucker rats. 345 May 49

One mechanism through which the brain obtains information about the composition of the diet involves food-induced changes in the plasma amino acid pattern (principally the "plasma tryptophan ratio"), which then cause increases or decreases in brain tryptophan levels, and in the synthesis of a neurotransmitter, serotonin, which is formed from the tryptophan. A carbohydrate-rich, protein-poor meal stimulates insulin secretion; this diminishes plasma levels of the amino acids which compete with tryptophan for transport into the brain (e.g., leucine, isoleucine and valine), thus increasing tryptophan's flux across the blood-brain barrier and its brain levels. In contrast, a high-protein meal contributes so much more of these latter amino acids to the blood stream than of the relatively-scarce tryptophan that it diminishes tryptophan's entry into the brain. This article reviews evidence that the brain actually utilizes the food-induced changes in brain serotonin in order to make choices about what to eat at the next meal. It also discusses the likelihood that a disturbance in this mechanism is involved in producing the "carbohydrate-craving" that is frequently associated with obesity. (This behavior which has been studied by allowing hospitalized subjects to choose freely among isocaloric meals and snacks of varying protein/carbohydrate ratios, typically manifests itself as a propensity to consume 30 per cent or more of the total daily calorie intake in the form of sweet or starchy snacks, usually at a characteristic time of day.) D-Fenfluramine, a drug that selectively enhances serotonin-mediated neurotransmission, also selectively suppresses "carbohydrate-craving" in these subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Carbohydrate craving, obesity and brain serotonin. 352 63

Very-low-calorie diets (less than 500 kcal/day; VLCD) are widely used for the treatment of severe obesity. We report the effects of such diets, consisting of proteins only or proteins and carbohydrates (CH), on nitrogen balance and protein nutritional status of morbidly obese patients. Cumulative nitrogen loss, serum albumin, transferrin, prealbumin (PA) and retinol-binding protein (RBP) concentrations, and plasma amino acid profile were determined in two groups of obese patients: 5 subjects (3 women, 2 men: BMI 55.3 +/- 2.2 kg/m2) subjected for 4 weeks to a protein VLCD (40 g protein + 2 g fat) and 7 others (4 women, 3 men: BMI 45.6 +/- 2.8 kg/m2) received for the same length of time a protein + CH VLCD (34 g protein + 26 g CH). Nitrogen balance was determined weekly whilst plasma and serum variables were measured on days 0, 3, 5, 10, 20 and 28 of treatment. Nitrogen balance did not significantly differ between the two groups of patients throughout the treatment. Serum PA and RBP concentrations decreased from day 5 and day 10, respectively, in both groups. Plasma amino acids showed a similar pattern in the protein and protein + CH groups. Alanine gradually decreased below baseline values; after a peak value on day 5, branched-chain amino acids (valine, leucine, isoleucine) returned to baseline values in both groups. In conclusion, in severely obese patients subjected to VLCD, nitrogen balance, labile protein concentrations and plasma amino acid profile are not significantly affected by adding CH to proteins.
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PMID:Protein balance during very-low-calorie diets for the treatment of severe obesity. 359 20

In order to test the hypothesis that serotonergic activity is abnormal in the brains of genetically obese Zucker rats, levels of serotonin (5-HT); its amino acid precursor, tryptophan (Trp), and its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA) were measured in eight brain regions in groups of obese and non-obese male rats. Plasma albumin levels as well as levels of amino acids and related compounds in plasma and in a cortical sample were also determined in the same animals. While Trp was lower in several brain regions of the obese animals, the only region showing a depressed level of 5-HT in the obese group was the mesencephalon. Obese animals also had a lower amount of 5-HIAA in the diencephalon, but no other differences were significant. Both elevations and depressions were observed in cortical amino acid levels in obese animals. The level of plasma albumin was increased in the obese group. Free Trp was decreased in the plasma of obese rats while levels of other amino acids (methionine, leucine, isoleucine, valine and phenylalanine) which compete with Trp for transport across the blood-brain barrier were elevated. Thus the combination of lower plasma free Trp and increased levels of competitive amino acids appears to contribute to decreased levels of Trp in the brain of genetically obese rats.
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PMID:Brain serotonergic activity and plasma amino acid levels in genetically obese Zucker rats. 618 36

The effect of euglycemic hyperinsulinism on branched-chain amino acids (BCAA; valine, isoleucine and leucine) was evaluated in five obese subjects and five controls. A continuous intravenous insulin infusion raised plasma insulin to a steady-state level. An artificial endocrine pancrease that infused glucose was used to sustain euglycemia. Basal and steady-state insulin levels were significantly higher in the obese subjects than in the controls. The amount of glucose infused to maintain euglycemia and its ratio to steady-state insulin levels was significantly lower in the obese subjects, suggesting an impaired insulin action on glucose metabolism. Basal BCAA levels were similar in the two groups of subjects. During insulin infusion the decremental areas of BCAA below basal levels were significantly lower in the obese patients (63 +/- 5 nmol/mL X min v 143 +/- 8 nmol/mL X min, P less than 0.001), as was the ratio of the decremental areas of BCAA to the incremental areas of insulin (1.11 +/- 0.05 nmol/microU v 3.30 +/- 0.24 nmol/microU, P less than 0.001). Our data suggest that insulin resistance in obesity reduces hormonal effects on glucose as well as on BCAA metabolism.
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PMID:Insulin-dependent metabolism of branched-chain amino acids in obesity. 636 75


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