Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most of the many metabolic abnormalities associated with obesity are corrected by weight reduction. Adipose-tissue lipoprotein-lipase activity per cell is increased in obesity. Adipose-tissue lipoprotein-lipase was significantly higher in seven previously obese men studied at a stable reduced weight than in a control population. In fact, enzyme activity was significantly higher than would have been predicted from the obese men's maximum weight. These results indicate that abnormalities in adipose-tissue lipoprotein lipase may have a primary role in the development of obesity.
 ...
PMID:Increased adipose-tissue lipoprotein-lipase activity in moderately obese men after weight reduction. 7 95

The aim of this study was to discover which of three major abnormalities of the genetically obese Zucker rat (fa/fa), namely hyperphagia, excess adiposity, and hyperlipidemia, is the first to appear prior to manifest obesity, i.e., before weaning. Suckling fa/fa rats, bred from heterozygous parents, were detected by sizing fat cells obtained from an inguinal fat pad biopsy. Cell hypertrophy was observed in fa/fa rats, compared to Fa/-littermates of the same sex, as soon as 5-7 days after birth. Prediction of fa/fa genotype at this age by this method was assessed using a series of 80 pups and proved to be totally successful. The identity of the "predicted" obese pups was confirmed morphologically at 6 weeks of age. Food (milk) intake was estimated from water turnover rates determined on 86 pups aged 2-8 days using tritiated water. The results show that 7-day-old fa/fa rats had heavier inguinal fat pads with larger adipocytes and higher lipoprotein lipase activity than their lean controls. There was no genotype effect on water intake adjusted to body weight during the first week of life. Moreover weight of stomach contents and triglyceridemia were similar in all animals at 7 days. These results show that excess adiposity develops in the fa/fa rat during the first week of life, before hypertriglyceridemia and hyperphagia, and raises the question of whether this adiposity results from a defect in energy expenditure or an abnormality of fat cell storage capacity, or both.
 ...
PMID:Onset of genetic obesity in the absence of hyperphagia during the first week of life in the Zucker rat (fa/fa). 29 Jul 21

1. Newborn rats were reared in litters of either four or sixteen individuals. The animals from the small litters gained body weight more rapidly than those from large litters during the first 29 days of postnatal life studied. 2. The relative weights of the perigenital, perirenal, subcutaneous and intramuscular white-adipose-tissue sites in the animals from small litters indicated their relative obesity compared with controls. 3. The adipose depots from animals reared in small litters had a greater proportion of lipid present, by weight, and had a greater number of larger fat-cells present in them compared with the depots of animals reared in large litters. 4. Compared with both normal-sized litter controls and animals reared in sixteens, during the period of study the animals from small litters were hypertriacylglycerolaemic but normocholesterolaemic. 5. During suckling the blood glucose concentrations of animals reared in fours were increased, as were the concentrations of circulating immunoreactive insulin. 6. During the 29 days of life studied, in general, the lipoprotein lipase activity of adipose depots from animals reared in fours was greater than for animals in large litters when expressed as mumol of nonesterified fatty acid released from the substrate/h per g fresh weight of tissue, per depot, or per million fat-cells, but were similar per cm(2) of fat-cell surface area. 7. The previously noted [Cryer & Jones (1978) Biochem. J.172, 319-325] pattern of mid-suckling elevation, late-suckling decline and post-weaning increase in the lipoprotein lipase activity of the four white-adipose depots studied was not obliterated by the nutritional manipulations employed. 8. The relation of the enzyme-activity changes and their hormonal stimuli to triacylglycerol accumulation in fat-cells of animals from large and small litters is discussed in relation to the possible significance they may have to our understanding of neonatally induced obesity.
 ...
PMID:The early development of white adipose tissue. Effects of litter size on the lipoprotein lipase activity of four adipose-tissue depots, serum immunoreactive insulin and tissue cellularity during the first four weeks of life in the rat. 57 19

In order to follow early metabolic adaptations in adipose tissue, which may lead to a decrease in fat cell size and body fat obtained by physical training, two sets of experiments were performed. Obese subjects and a control group exercised on a bicycle at two-thirds of maximal working capacity for one hour. Twenty-four hours thereafter, either on ad libitum diet, or on an isocaloric diet supplemented with calories corresponding to the expanded calories during the work load, an adipose tissue biopsy was taken and fat cell metabolism studied. In obese subjects on and ad libitum or on an isocaloric diet the lipolytic process was increased after the exercise but no significant effects were found on the rates of glucose metabolism. Furthermore, a relationship between cell surface and metabolism was found before, but not after, the work in all groups. No changes were seen in lipoprotein lipase activity. Obese subjects on a controlled diet showed a somewhat higher insulin and catecholamine responsiveness of adipocytes than was the case in the obese subjects on an ad libitum diet. This may well be due to the differences in carbohydrate intake, a factor of importance for hormonal responsiveness of fat cells. The increased basal lipolysis after exercise may be caused by the release of lipolytic hormones, and may well be the first sign of an adaption of the organism to diminish the fat stores as seen in physically trained subjects.
 ...
PMID:Effects of submaximal physical exercise on adipose tissue metabolism in man. 61 37

Published studies have shown that overproduction of very low density lipoproteins is a major factor leading to hypertiglyceridemia in obesity. Few systematic studies of triglyceride removal or postheparin lipoprotein lipase activity (LPLA) in obesity have appeared. We have examined heparin-released lipoprotein triglyceride hydrolase activities in 12 lean and 12 obese age- and sex-matched volunteers after overnight fasting. Heparin doses were calculated to compensate for the disproportionality between body mass and plasma volume in obesity. Triglyceride hydrolase activities of hepatic (HTGLA) and extrahepatic (LPLA) origin were distinguished by in vitro inhibition of LPLA with protamine sulfate. Incremental heparin doses were given to each subject to determine lipase activities under conditions of maximal release and to define sensitivity to heparin-facilitated lipase release. Maximal postheparin LPLA and HTGLA (u/ml plasma or u/total plasma vol) were similar in lean and obese individuals despite a nearly three-fold increase in calculated adipose tissue mass in the obese. Since adipose tissue LPLA has been reported to increase in proportion to adipocyte size, the lack of difference in maximal postheparin LPLA was expected. There was an inverse correlation between plasma triglyceride concentration and LPLA/kg adipose tissue. These empirical observations may reflect relatively decreased heparin-releaseable (functional) LPLA in relation to adipose organ mass in obese subjects. The mechanism of this relationship has not been established.
 ...
PMID:Postheparin plasma lipase activities in obesity: failure to increase with adipose organ enlargement. 68 71

There was a positive correlation in normal man between heparin releasable lipoprotein lipase and lipoprotein lipase of ammonium hydroxide homongenate of acetoneether powder in adipose tissue. Heparin releasable as lipoprotein lipase activity was about twice as high as the enzymatic activity in acetone powder, even though 40-70% of the original activity remained in the tissue after incubation with heparin. This might indicate that activation of the enzyme is associated with its release by heparin from tissue. The lipoprotein lipase activity per unit weight and per fat cell were affected differently by obesity: In obese subjects lipoprotein lipase per unit weight was propotionally lower than the activity per fat cell. The expression of activity per fat cell appears to avoid the effect of obesity, and hence increased fat cell size, on values obtained.
 ...
PMID:Human adipose tissue lipoprotein lipase: comparison of assay methods and expressions of activity. 112 69

In 13 obese children plasma triglyceride concentrations were found to be significantly elevated, while plasma cholesterol concentrations were normal. In the hypertriglyceridemic obese children, the plasma fractional triglyceride removal, measured by the intravenous fat tolerance test, was significantly reduced. These abnormalities reverted to normal in 8 patients retested after weight loss. Plasma postheparin lipoprotein lipase activity was found to be increased and significantly related to the degree of obesity. As to carbohydrate metabolism, a decreased glucose tolerance and hyperinsulinemia were found. Hyperinsulinemia reverted to normal during dietary restriction, glucose intolerance did not.
 ...
PMID:Plasma triglyceride clearing in obese children. 114 45

The role of insulin in the regulation of human adipose tissue lipoprotein lipase was evaluated. Adipose tissue heparin-releasable lipoprotein lipase (thought to be related to peripheral clearance of plasma triglycerides) was low in insulin-deficient, untreated hyperglycemic diabetic subjects (P less than 0.001) and treatment of hyperglycemia returned the activity to normal. In chronic hyperinsulinism, represented by obesity, heparin-releasable activity among control subjects was correlated to percent of ideal body weight (r=0.53, P less than 0.05) and to fat cell size (r=0.61, P less than 0.02). Acetone-ether powder lipoprotein lipase activity (presumed to reflect total tissue enzyme) was also related to percent of ideal body weight (r=0.76, P less than 0.001 for controls; r=0.67, P less than 0.05 for diabetics) and to fat cell size (r=0.71, P less than 0.01 for controls; r=0.85, P less than 0.01 for diabetics. Postprandial-stimulated insulin secretion was related to diet-induced changes in lipoprotein lipase in control subjects; both were dependent upon the amount of dietary carbohydrate. In contrast, the diabetic patients with low insulin responses, failed to increase lipoprotein lipase activity with feeding. The changes in heparin-releasable (r=0.66, P less than 0.01) and acetone-ether powder (r=0.69, P less than 0.01) activity during feeding were related to the percent increase in plasma insulin. Thus, insulin appears to be important in the regulation of human adipose tissue lipoprotein lipase activity. Elevated insulin levels in obesity and increased insulin secretion after eating were associated with increased lipoprotein lipase activity. Defects in insulin secretion, both in postabsorptive and postprandial states, are associated with low adipose tissue lipoprotein lipase and may lead to hypertriglyceridemia in diabetic man.
 ...
PMID:Determinants of human adipose tissue lipoprotein lipase. Effect of diabetes and obesity on basal- and diet-induced activity. 118 38

Published data have suggested that hypertriglyceridemia in obesity may result from the combination of hepatic overproduction and diminished removal of triglyceride-rich lipoproteins. Diminished catabolism might be expected if tissue lipoprotein lipase activity were decreased, a finding which has been reported in biopsies of adipose tissue from obese subjects. Abnormalities in heparin-released triglyceride lipase activity (PHLA) in obesity have not been reported, however. We have examined the possibility that methods for the measurement of PHLA might have failed to reveal such a defect because of the disproportionality between plasma volume and increasing body mass in obesity. Since it is usual to administer heparin on the basis of body weight, higher plasma heparin levels would be achieved in obese individuals. We performed standard PHLA assays in lean and obese volunteers. In the obese, heparin levels were consistently higher than in lean individuals although PHLA values were similar in both. Thus, PHLA in obesity appeared to be inappropriate for the heparin levels attained in plasma. Pharmacokinetic studies suggest that a decrease in PHLA available for release by heparin rather than heparin insensitivity underlies this phenomenon.
 ...
PMID:Abnormal post-heparin lipolytic activity in obesity. A preliminary note. 120 Nov 46

Lean mice were made obese by feeding, ad libitum, a high-lard diet. They showed an increased fat cell size and number which were maintained when this diet was replaced by the control high-carbohydrate diet for 10 weeks. Obese fed mice showed normal glucose and insulin serum levels, but insulinaemia was elevated after an overnight fast. The insulinaemic response after intraperitoneal injection of glucose was insignificant. Thus hyperinsulinism is not a prerequisite for the development of obesity. High-fat diet influenced, in vitro, glucose metabolism of adipose tissue, liver and muscle: basal lipogenesis was markedly reduced in adipose tissue and liver, and glucose oxidation was decreased in muscle. Insulin sensitivity was reduced by increased fat cell size. De novo formation of fatty acids in liver and adipose tissue did not contribute to the development of obesity. The increased lipoprotein lipase activity of the large fat cells suggested that obesity resulted from a direct storage of dietary fatty acids esterified by glycerol formed from circulating glucose.
 ...
PMID:Metabolism of the mouse made obese by a high-fat diet. 123 69


1 2 3 4 5 6 7 8 9 10 Next >>