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

Estimates of the quantitative contribution of adipose tissue to whole-body glucose metabolism, previously reported as 1-3%, have been revised to be on the order of 10-30%. These revised estimates come, in part, from a recognition that adipose tissue uses glucose to produce lactate and pyruvate, in addition to CO2 and triglycerides. Lactate production by adipose tissue is modulated in vitro by changes in glucose, insulin, and epinephrine concentrations. In vivo, lactate production is regulated acutely by the animal's nutritional state (fed or fasted) and chronically by the degree of obesity. A strong positive correlation exists between rat fat cell size and relative conversion of glucose to lactate (r = 0.89, P less than 0.001). Diabetes is also associated with markedly increased lactate production in adipocytes. Fat cells from obese or diabetic rats (or humans) can metabolize to lactate as much as 50-70% of the glucose taken up. From these recent studies, a picture is emerging in which the adipose organ may provide lactate for hepatic gluconeogenesis during fasting, and also lactate for hepatic glycogen synthesis after food ingestion. Modulation of adipocyte lactate production and contribution of adipose tissue lactate to the body's fuel economy in physiological and pathological states are the focus of this review.
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PMID:Lactate production in adipose tissue: a regulated function with extra-adipose implications. 156 93

The purpose of this study was to assess the efficacy of bi-level positive airway pressure (BiPAP) ventilation through a nasal mask in the treatment of eight patients with hypoventilatory respiratory failure and nocturnal CO2 retention. Nocturnal CO2 retention was significantly reduced in all patients with the application of BiPAP during sleep (p less than 0.01). Daytime somnolence was relieved and dyspnea improved after three months of home BiPAP therapy. All patients tolerated home BiPAP therapy, and two patients who had previously been treated with volume ventilation via nasal mask found BiPAP more comfortable. There were no changes in FEV1 or FVC after three months of BiPAP. Daytime PaCO2 improved slightly or remained stable in all patients after three months of home BiPAP. BiPAP nasal ventilation is effective in reducing nocturnal CO2 retention short term in hypoventilatory respiratory failure due to obesity hypoventilation syndrome, chest wall restriction, or neuromuscular disease. Further studies in patients with COPD may be warranted.
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PMID:Nocturnal nasal intermittent positive pressure ventilation with bi-level positive airway pressure (BiPAP) in respiratory failure. 173 82

1. Lipid mobilization during a hypocaloric diet may be enhanced by a pharmacological approach using alpha 2-adrenoceptor antagonists since these drugs are known to increase sympathetic tone and stimulate lipolysis. Studies were undertaken in the dog in order to evaluate the effects of oral yohimbine administration (alpha 2-adrenoceptor antagonist) on heat production, metabolic, endocrinological and cardiovascular parameters. 2. Acute oral yohimbine (0.25 or 0.40 mg kg-1) provoked an increase in plasma non-esterified fatty acids. The drug increased sympathetic nervous system activity as indicated by the increased level of plasma noradrenaline. These effects persisted during the entire experimental period (4 h). The increase in plasma noradrenaline level was two fold higher with the higher dose of yohimbine (0.4 mg kg-1). The plasma adrenaline level was increased only with the higher dose. 3. Yohimbine transiently increased plasma insulin and the effect was dose-dependent. 4. Yohimbine (0.25 mg kg-1) enhanced heart rate and arterial blood pressure. 5. The effect of yohimbine on oxygen consumption, carbon dioxide and heat production was determined by indirect calorimetry. The drug (0.25 mg kg-1) increased O2 consumption and CO2 and heat production 30 min after its administration and the effect persisted over the experimental period. The respiratory quotient, rather low in the fasting animals, remained unchanged. 6. The present work indicates that thermogenesis and lipid mobilization are enhanced during fasting in the dog by alpha 2-adrenoceptor blockade. Yohimbine also induced a transient increase in plasma insulin level and increased heart rate and blood pressure. The lipid mobilization plus the action on thermogenesis observed after yohimbine draw attention to the putative interest of a2-antagonists in the pharmacological treatment of obesity during restricted calorie intake.
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PMID:Thermogenic and lipolytic effect of yohimbine in the dog. 179 15

Pulmonary function and pulmonary gas exchange at rest, and during and after a standard exercise load of 500 kpm in 1 min on bicycle ergometer were studied in 34 women with severe, uncomplicated obesity, aged 37.8 (20-59) years, before and 1 year after gastric banding, resulting in a weight loss from 113.2 (84-156) to 81.7 (60-110) kg. Following the weight loss, TLC and VC rose from 93 and 94 per cent of expected to 98 and 101 per cent, respectively. FRC, ERV and FRC/TLC rose more markedly from 77, 64 and 83 per cent to 98, 109 and 99 per cent. IC fell from 108 to 99 per cent. RV and RV/TLV remained unchanged. FEV1.0 rose from 97 to 103 per cent, while MVV rose from 102 to 112 per cent, i.e. above normal. TLCO and PaCO2 remained unchanged, at 90 and 95 per cent, whereas PaO2 rose from 86 to 91 per cent. Resting O2 intake (VO2) decreased from 147 to 115 per cent of the expected for normal weight women, while VO2/BSA decreased from 113 to 99 per cent, the changes being greater than expected from commonly used formulas for prediction of metabolic rate. O2 cost of work (EO2) decreased from 142 to 105 per cent. Resting ventilation (V) declined from 136 to 113 per cent, while ventilatory cost of work (EV) decreased from 142 to 105 per cent. CO2 recovery time after work (CO2RT) decreased from 121 to 100 per cent, while the ratios CO2RT to EO2 and to extra CO2 output of work (ECO2) rose slightly. Thus, the loss of weight led to increased filling of the lungs, improved dynamic function, reduced ventilation/perfusion disturbances and greater than expected reduction of energy expenditure, both at rest and exercise. In the obese state there was no evidence of alveolar hypoventilation or impaired ventilatory control. The beneficial effect of weight reduction on the exertional dyspnea included a combination of marked reduction of ventilatory demands and moderate rise in ventilatory capacity.
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PMID:Pulmonary function and energy expenditure after marked weight loss in obese women: observations before and one year after gastric banding. 211 Dec 93

An obese woman with respiratory failure and bilateral diaphragmatic paralysis, was studied in order to investigate the effects of weight loss on respiratory function during wakefulness and sleep. The patient was studied on 5 different occasions during which diurnal blood gas analysis, spirometry, CO2 rebreathing test, nitrogen wash-out test and a nocturnal polysomnographic study were performed. The follow-up period lasted 9 months, during which the patient progressively lost 19 kg. Progressive improvement in awake blood gas tensions (PaO2 + 21 mmHg, PaCO2 - 16 mmHg) as well as in nocturnal oxyhemoglobin saturation and transcutaneous PCO2 were observed; at the same time only minor changes in responsiveness to CO2 and in lung volumes were found. Conversely alveolar efficiency for CO2, obtained with the nitrogen wash-out test, in the supine posture increased from 81.7 to 90.5%, indicating an improvement in ventilation/perfusion ratio as a possible determinant of blood gas tension improvement during wakefulness and, as a consequence, also during sleep. We conclude that obesity is one possible cause of the occurrence of respiratory failure in bilateral diaphragmatic paralysis.
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PMID:Obesity as a possible cause of respiratory failure in bilateral diaphragmatic paralysis. Case report. 248 95

To gain insight into cellular events associated with the progression of obesity to diabetes, we have studied glucose metabolism and insulin responses in adipocytes from monkeys with spontaneous obesity. Over a 3- period, we studied animals which (A) remained relatively lean; (B) became obese (over 30 percent body fat) with normal glucose tolerance; (C) were obese and developed hyperinsulinemia (over 100 microU/ml); and (D) were obese and subsequently developed noninsulin-dependent diabetes (NIDDM) (fasting plasma glucose above 140 mg/dl and abnormal glucose tolerance test). Adipocyte glucose utilization, evaluated by conversion of 14-C-glucose to CO2 and lipids, was measured in the absence and presence of varying concentrations of insulin, using cells prepared from biopsy samples of subcutaneous abdominal fat. The major change in adipocyte metabolism was a decrease in basal and insulin-stimulated glucose utilization in NIDDM, relative to the enhanced responses observed in cells from the obese-hyperinsulinemic monkeys. Longitudinal studies of individual monkeys over 2-3 years led to the following additional observations regarding adipocyte glucose metabolism. Basal and insulin-stimulated glucose utilization dropped markedly as hyperinsulinemia progressed into diabetes. As impairments in glucose tolerance worsened in diabetes, adipocytes showed only a modest or negligible additional impairment in basal and insulin-stimulated glucose oxidation. Insulin binding was reduced in adipocytes from monkeys with obesity as compared to lean controls, and was similar in cells from monkeys with obesity and NIDDM. In the monkeys, obesity was initially associated with enhanced adipocyte metabolism. With the spontaneous development of NIDDM, glucose metabolism in adipocytes was depressed. The progression of metabolic events from hyperinsulinemia to NIDDM in monkeys includes cellular changes in insulin responses at the level of the adipocyte.
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PMID:Changes in insulin responses and binding in adipocytes from monkeys with obesity progressing to diabetes. 306 66

The effects of isocapnic hyperventilation (A) and normoventilation (B) on PaCO2, PaO2 and A-aDO2 were compared in 102 patients undergoing elective surgery, randomized into two comparable groups A and B. Cases for thoracic, high abdominal and intracranial surgery were excluded, as well as patients with clinically evident pulmonary pathology. A volumetric ventilator was used in association with three different breathing systems (A: Bain system and circle system without CO2 absorption; B: circle system with CO2 absorption). The groups were comparable, except for percentage of overweight: 75% in group A and 56% in group B. Overweight was defined as weight above the mean ideal weight of 100%, and obesity as a weight above 120% the mean ideal weight. Blood gases were sampled 1) preoperatively, 2) 15 min and 3) 60 min after the beginning of mechanical ventilation, 4) postoperatively, 90 min after extubation, without supplemental oxygen. The preoperative mean PaO2 values were 79 +/- 11.4 mmHg (A) and 82.5 +/- 13.2 mmHg (B); the PaCO2 were 37.2 +/- 3.7 mmHg (A) and 37.2 +/- 3.8 mmHg (B). During surgery, PaO2 was distinctly higher (p less than 0.01) in group A than in group B (on average 15-20 mmHg higher), indicating the favourable effect of great tidal volumes on gas exchange. Correspondingly, the A-aDO2 was less increased in group A than in group B (p less than 0.01). At 15 min, 33% of the patients were hypocapnic (PaCO2 less than 35 mmHg): one case in group A and three in group B could be classed as severe hypocapnia (PaCO2 = 25-30 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Per- and post-operative gas exchange: isocapnic hyperventilation versus normoventilation]. 312 83

The doubly labeled water method is a form of indirect calorimetry that has been developed only recently to the stage of application to human studies. The method measures integral CO2 production for up to 3 wk from the difference in elimination rates of deuterium and 18O from labeled body water. Validations against near-continuous respiratory gas exchange have demonstrated that the method is accurate and has a precision of 2-8% depending on the isotope dose and the length of the elimination period. Although the method has been validated, there is still some debate on refinements of the kinetic model that may lead to improved accuracy and precision. Because the method only requires periodic sampling of body fluids, it is non-restrictive and ideally suited to use in free-living subjects. Recent applications of the method have included obesity research, determination of energy requirements in both developing and developed countries and studies of human growth.
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PMID:Measurement of energy expenditure in free-living humans by using doubly labeled water. 314 75

Morbid obesity is not infrequently associated with severe respiratory impairment. In our experience approximately 10 per cent of morbidly obese patients who underwent gastric surgery had severe respiratory impairment. Respiratory insufficiency of obesity can be divided into two primary breathing disorders: the obstructive sleep apnea syndrome (SAS) and the obesity hypoventilation syndrome (OHS). In its most severe form, when both SAS and OHS are present, it is called the Pickwickian syndrome. In our series 59 morbidly obese patients with respiratory insufficiency secondary to obesity underwent gastric surgery for weight reduction. Fourteen had OHS, 19 had SAS and 26 had both. Of these, two patients died of postoperative complications and one died at five weeks with an inconclusive autopsy, totalling an operative mortality rate of 3.4 per cent and a total mortality of 5.1 per cent. In our overall experience morbidly obese patients lost 67 per cent of excess weight after gastric procedures. In conclusion, surgically induced weight loss will markedly improve or correct respiratory insufficiency secondary to obesity. It will improve arterial oxygenation, minimize CO2 retention, expand lung volumes, correct polycythemia, and reduce apnea frequency. The magnitude of changes in these variables is clinically significant. Therefore, respiratory insufficiency of obesity should be considered a major indication for an aggressive approach to weight reduction. The jejunoileal bypass and unbanded gastroplasty operations have an unacceptable incidence of complications or failure, respectively. There is a high degree of recidivism following dietary programs. Sweets eaters will not do well with a gastroplasty procedure. Gastric bypass for individuals addicted to sweets or the vertical banded gastroplasty for "gorgers" are currently our procedures of choice and are associated with the average loss of two thirds of excess weight and correction of breathing problems associated with morbid obesity.
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PMID:Pulmonary function in morbid obesity. 331 3

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


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