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

Obesity is an increasingly prevalent problem, and long-term maintenance of the weight-reduced state is difficult for the obese individual. Following weight reduction, many metabolic changes occur. Among these is an increase in adipose tissue lipoprotein lipase (ATLPL), which predicts an alteration in lipid fuel partitioning which may then contribute to resumption of the obese state. The purpose of this study was to test whether changes in skeletal muscle LPL (SMLPL) and its response to insulin/glucose after sustained weight reduction also indicate a potential altered partitioning of lipid fuels away from oxidative pathways in muscle to storage in adipose tissue. Biopsies of vastus lateralis muscle were carried out in premenopausal obese women (n = 11, 94 +/- 4 kg, mean +/- SEM) before and after consumption of a 900 kcal day-1 diet for 3 months followed by 3 months of isocaloric maintenance of the reduced weight (n = 11, 82 +/- 4 kg). SMLPL activity was measured in the fasted state and after 6 h insulin/glucose infusion, before and after sustained weight loss. SMLPL activities were also measured in six normal weight women. Fasting SMLPL activity in obese women (3.9 +/- 0.3 nmol FFA min-1 g-1) was similar to that measured in normal weight control women (4.4 +/- 0.5). Unlike normal weight controls in whom a 6 h insulin/glucose infusion decreased SMLPL activity, in obese women the response of SMLPL was positive (normal weight vs. obese: delta -0.8 +/- 0.3 vs. delta 1.6 +/- 0.5, P = 0.002). Following maintained weight reduction, fasting SMLPL in the obese group was reduced to 1.2 +/- 0.3 (obese before weight loss vs. obese after: P = 0.0001). This change in fasting SMLPL activity following weight loss/maintenance correlated with the resultant change in percent body fat (r s = 0.663, P = 0.026).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sustained weight reduction in moderately obese women results in decreased activity of skeletal muscle lipoprotein lipase. 765 17

The tripeptide hormone, TRH, is metabolized by three enzymes, the most specific of which is pyroglutamyl peptide hydrolase-II (also termed thyroliberinase), a metalloenzyme present in serum and brain. Because pyroglutamyl peptidase-II activity in rat serum is regulated by thyroid hormone levels, we tested the hypothesis that this activity is similarly altered in humans. We studied serum pyroglutamyl peptidase-II activity in 6 patients with hyperthyroidism, 18 patients with hypothyroidism, and 31 euthyroid, normal weight volunteers. Because TRH [or its metabolite cyclo(His-Pro)] is believed to be an important hormone regulating appetite and metabolism, we also evaluated pyroglutamyl peptidase-II activity in 27 euthyroid patients with obesity. Serum pyroglutamyl peptidase-II activity was elevated in patients with hypothyroidism (mean +/- SEM, 33.9 +/- 3.7 nmol/mL.h) compared to that in euthyroid, normal weight volunteers (24.5 +/- 2.8 nmol/mL.h; P < 0.05), but not that in patients with hyperthyroidism (28.3 +/- 4.1 nmol/mL.h; P = NS). Euthyroid obese patients had the highest pyroglutamyl peptidase-II activity (43.6 +/- 2.8 nmol/mL.h; P < 0.0001 vs. normal weight volunteers). Pyroglutamyl peptidase-II activity was positively correlated with body mass index (r2 = 0.30; P < 0.0001). After correction for body mass index, there were no difference in pyroglutamyl peptidase-II activity in hypothyroid, hyperthyroid, and euthyroid individuals. We conclude that serum pyroglutamyl peptidase-II activity is regulated by, or regulates, body weight.
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PMID:Pyroglutamyl peptidase-II ("thyroliberinase") activity in human serum: influence of weight and thyroid status. 771 73

Human obesity is characterized by profound alterations in the hemodynamic and metabolic states. Whether these alterations involve sympathetic drive is controversial. In 10 young obese subjects (body mass index, 40.5 +/- 1.2 kg/m2, mean +/- SEM) with normal blood pressure and 8 age-matched lean normotensive control subjects, we measured beat-to-beat arterial blood pressure (Finapres technique), heart rate (electrocardiogram), postganglionic muscle sympathetic nerve activity (microneurography at the peroneal nerve), and venous plasma norepinephrine (high-performance liquid chromatography). The measurements were performed in baseline conditions and, with the exception of plasma norepinephrine, during baroreceptor stimulation and deactivation caused by increases and reductions of blood pressure via intravenous infusions of phenylephrine and nitroprusside. Baseline blood pressure and heart rate were similar in obese and control subjects. Plasma norepinephrine was also similar in the two groups. Muscle sympathetic nerve activity, however, was 38.6 +/- 5.1 bursts per minute in obese subjects and less than half that level in control subjects (18.7 +/- 1.3 bursts per minute), the difference being highly statistically significant (P < .02). Muscle sympathetic nerve activity and heart rate were reduced during phenylephrine infusion and increased during nitroprusside infusion, but the changes were about half as great in obese subjects as in control subjects. Thus, even in the absence of any blood pressure alteration, human obesity is characterized by a marked sympathetic activation, possibly because of an impairment of reflex sympathetic restraint. This may be involved in the high rate of hypertension and cardiovascular complications seen in obesity.
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PMID:Sympathetic activation in obese normotensive subjects. 772 98

A low level of sympathetic nerve activity (SNA) to brown adipose tissue has been found in genetically obese Zucker rats and may promote obesity through decreased thermogenesis. In contrast, acquired obesity is reportedly associated with increased SNA. To determine whether low SNA levels in obese Zucker rats extend to the kidney, we compared baseline levels of renal SNA in obese and lean conscious unrestrained Zucker rats fed for 2 weeks on low salt (0.4% NaCl) and high salt (8.0% NaCl) diets. Baseline renal SNA was calculated from multifiber recordings obtained before death under conscious, resting conditions and after death. Body weight averaged 490 +/- 12 g (mean +/- SEM) in obese rats (n = 17) and 339 +/- 7 g in lean rats (n = 19). Mean arterial pressure did not differ in obese and lean Zucker rats fed the low salt diet. However, on the high salt diet, mean arterial pressure was significantly higher in obese rats (n = 8) than in lean rats (n = 9) (113 +/- 3 and 101 +/- 3 mm Hg, respectively; P < .05). Baseline renal SNA was approximately 2 to 2.5 times higher (P < .05) in obese rats than in lean rats in all groups. These studies suggest that obese Zucker rats have heightened levels of SNA to the kidney in contrast to reduced SNA to brown adipose tissue.
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PMID:Renal sympathetic nerve activity is increased in obese Zucker rats. 772 40

Insulin binding has been reported to be decreased in non-insulin-dependent diabetes mellitus (NIDDM). Although elevated basal insulin concentrations have been correlated with decreased insulin binding in obesity, this relationship has not been found in NIDDM. To determine the potential cause(s) of the decrease, we measured 125I-insulin binding to circulating monocytes isolated from 31 non-insulin-treated patients with NIDDM who had a fasting plasma glucose (FPG) concentration greater than 7.8 mmol/L and 13 control subjects. We examined the influence of obesity, insulin concentration, glycemic control, and treatment with oral hypoglycemic agents on insulin binding in a cross-sectional study. Insulin binding was significantly decreased in the entire NIDDM group (mean +/- SEM, %/10(7) monocytes: 4.65 +/- 0.33) as compared with controls (6.45 +/- .70, P < .02). Subgroups defined by obesity (relative body weight > 1.2) and poor glycemic control (FPG > 11.1 mmol/L) and those not taking oral hypoglycemic agents had significantly lower insulin binding (P < .02). However, neither relative body weight nor insulin concentrations (basal or stimulated) correlated with insulin binding. Stepwise linear regression analysis showed that only FPG significantly correlated with insulin binding (r = -.45, P = .002) even when oral hypoglycemic agent-treated patients were removed from the analysis (r = -.50, P = .003). There was no significant contribution to explain insulin binding by the other variables, including diagnosis of diabetes, obesity, insulin concentration, or treatment with oral hypoglycemic agents. We conclude that poor metabolic control is associated with an alteration in insulin receptor regulation in NIDDM.
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PMID:Insulin binding in non-insulin-dependent diabetes mellitus (NIDDM) is correlated with glycemic control: clinical evidence for abnormal receptor regulation in NIDDM. 772 74

Growth hormone (GH) secretion in response to all provocative stimuli is decreased in patients with obesity. Recently, we found that the combined administration of GH-releasing hormone (GHRH) and the hexapeptide GH-releasing peptide-6 (GHRP-6) induced a large increase in plasma GH levels. To gain further insight into the disrupted mechanism of GH regulation in obesity, we investigated whether the inhibition of somatostatinergic tone with pyridostigmine could further increase the GH response to combined administration of GHRH and GHRP-6. In normal subjects, administration of GHRH plus GHRP-6 induced a marked increase in plasma GH with a peak at 30 minutes (mean +/- SEM, 76.7 +/- 9.7 micrograms/L), which was similar to that obtained after pretreatment with pyridostigmine (74.7 +/- 9.4 micrograms/L). In obese patients, combined administration of GHRH plus GHRP-6 induced a clear increase in GH secretion with a peak at 15 minutes of 42.2 +/- 10.0 micrograms/L, which was also unaffected after pretreatment with pyridostigmine (38.4 +/- 5.8 micrograms/L). The GH response was lower in obese patients than in controls as assessed by the area under the curve after administration of both GHRH plus GHRP-6 (1,846 +/- 396 v 4,773 +/- 653, P < .01) and pyridostigmine plus GHRH plus GHRP-6 (1,989 +/- 372 v 5,098 +/- 679, P < .005). In conclusion, these data suggest that GHRP-6 can behave as a functional somatostatin antagonist, and that somatotrope responsiveness to the combined administration of GHRH plus GHRP-6 is largely independent of somatostatinergic tone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of combined administration of growth hormone (GH)-releasing hormone, GH-releasing peptide-6, and pyridostigmine in normal and obese subjects. 778 58

The purpose of this study was to determine whether genetically obese Wistar fatty rats have higher blood pressure than their lean littermates and if so to elucidate the mechanism of this obesity-related hypertension. We measured blood glucose and plasma insulin levels, blood pressure, and catecholamine and sodium excretions in age-matched female Wistar fatty and lean rats. After 12 weeks of age, the body weight of Wistar fatty rats was significantly greater than that of their lean counterparts. Fasting blood glucose and plasma insulin concentrations were higher in the fatty than the lean rats throughout the observation period (8 to 24 weeks of age). Systolic blood pressure of fatty rats measured by the tail-cuff method was similar to that of lean rats at 8 weeks of age (135 +/- 2 [mean +/- SEM] versus 134 +/- 3 mm Hg) but significantly higher at 16 (158 +/- 2 versus 136 +/- 3 mm Hg, P < .01) and 24 (166 +/- 5 versus 142 +/- 2 mm Hg, P < .01) weeks of age. Urinary norepinephrine excretion was significantly increased in the fatty rats at both 16 (1755 +/- 173 versus 977 +/- 128 ng/24 h, P < .05) and 24 (1907 +/- 283 versus 737 +/- 173 ng/24 h, P < .01) weeks of age. The ratio of urinary norepinephrine excretion to body weight was also significantly increased in the fatty rats. These results show that with increasing body weight Wistar fatty rats develop hypertension, which may be attributable to an increased sympathetic nerve activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Wistar fatty rat is obese and spontaneously hypertensive. 784 47

1. Recent molecular genetic studies have implicated the low-density-lipoprotein receptor gene locus (LDLR, at chromosome 19p13.2) in obesity in essential hypertensive patients and in the atherogenic lipoprotein phenotype. The present study examined genotypes for the obesity-associated ApaLI restriction fragment length polymorphism of LDLR, and genotypes for a hypertension-associated RsaI restriction fragment length polymorphism at the insulin receptor gene (INSR) locus, which is linked to LDLR, in relation to plasma lipids, body mass index and blood pressure in 27 obese and 57 non-obese Caucasians with severe essential hypertension, selected on the basis of having parents who were both hypertensive, and in 25 obese and 45 non-obese normotensive subjects selected on the basis of having parents who were both normotensive after the age of 50 years. 2. Plasma triacylglycerol and low-density-lipoprotein-cholesterol were elevated in hypertensive patients, but did not differ between the obese and non-obese hypertensive groups. Significant positive correlations were seen between body mass index and triacylglycerol and low-density-lipoprotein-cholesterol in the obese and non-obese hypertensive patients, respectively. In addition, obese hypertensive patients had significantly higher diastolic blood pressure than non-obese hypertensive patients. 3. The eight obese hypertensive patients who were homozygous for the obesity-associated 6.6 kb allele of the ApaLI restriction fragment length polymorphism of LDLR ('6.6. kb homozygotes') had a significantly higher body mass index [34 +/- 6.0 (SD) kg/m2] than the 18 heterozygotes (29 +/- 2.7 kg/m2) and the single subject who was homozygous for the 9.4 kb allele (29 kg/m2) (P = 0.012 by one-way analysis of variance). The body mass index of the eight hypertensive 6.6 kb homozygotes was also greater than the body mass index of 29 +/- 2.4 kg/m2 observed for the eight obese normotensive 6.6 kb homozygotes. In addition, the eight obese hypertensive 6.6 kb homozygotes had a higher plasma triacylglycerol [4.2 +/- 0.77 (SEM) mmol/l] than the 18 obese hypertensive heterozygotes (2.4 +/- 0.33 mmol/l; P = 0.045). Non-obese hypertensive patients showed no significant genotypic differences in relation to the LDLR restriction fragment length polymorphism. 4. In the normotensive group, however, the frequency of the 6.6 kb allele of the LDLR ApaLI restriction fragment length polymorphism in obese subjects (0.54) was not significantly greater than in non-obese subjects (0.48) [cf. the significantly (P = 0.004( different values of 0.63 and 0.39, respectively, in obese and non-obese hypertensive patients.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Significant relationships of plasma lipids and body mass index with polymorphisms at the linked low-density-lipoprotein receptor gene and insulin receptor gene loci (19p13.2) in essential hypertensive patients. 803 1

The purpose of the study was to evaluate the current health status of male ambulance personnel based in Belfast, taking the opportunity to compare results with those from a comparable local survey of the general population. Risk factors for coronary heart disease were assessed. Ninety-three men were studied. Blood pressure values were significantly higher (P < 0.05) in the present study than in a comparable local survey of the general population, with 23 per cent of systolic values being over 140 mmHg and 27 per cent of diastolic readings being over 90 mmHg. The incidence of self-reported smoking was also higher in the ambulance service (36 per cent) compared with the local population (31 per cent). Computation of body mass indices for ambulancemen showed that 52 per cent of personnel fell outside the acceptable range of 20-25 kg/m2 with 10 per cent being greater than 30 kg/m2, recognized as the threshold of clinical obesity. With regard to serum cholesterol, 52 per cent of personnel exceeded the desirable threshold of 5.2 mmol/l, while 18 per cent were above 6.4 mmol/l. In addition, the high density lipoprotein fraction was significantly lower (P < 0.05) in the ambulancemen compared with the general population (mean +/- SEM: 1.10 +/- 0.3 vs 1.18 +/- 0.01, respectively). Although 54 per cent of the sample claimed to be physically active, only 35 per cent reportedly took sufficient exercise to be of benefit to their health. Cardiorespiratory fitness was significantly higher in this group. The ambulance service nationally remains the only emergency service without a strategy for health and fitness.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The health status of an ambulance service. 791 97

Long term changes in the secretion of prolactin were monitored in groups of hypothalamo-pituitary disconnected rams (HPD rams, n = 8) and control rams (HPD sham-operated and unoperated, n = 8) while exposed to an artificial lighting regimen of alternating 16-weekly periods of long days (16L:8D) and short days (8L:16D) for 72 weeks, and during a treatment with subcutaneous constant-release implants of melatonin under long days. The HPD rams showed all the clinical characteristics of complete pituitary disconnection (diabetes insipidus, gonadal regression and slight obesity), and were unresponsive to a range of provocation tests (exposure to a barking sheep dog, cannulation of the jugular vein, injection of serotonin and NMDA) which caused acute changes in the blood plasma concentrations of prolactin in the controls. Nevertheless, there was a clearly defined cycle in the blood concentrations of prolactin in the HPD rams related to the imposed lighting regimen with values 10-fold higher under long days compared to short days (HPD mean +/- SEM: 90.1 +/- 24.7 vs 9.4 +/- 2.0 micrograms/l, long vs short day respectively, P < 0.001). The temporal pattern was very similar to that observed in the controls, although the concentrations of prolactin were higher in the HPD rams and more variable (control mean +/- SEM: 55.6 +/- 3.6 vs 3.0 +/- 0.5 micrograms/l, long vs short day, P < 0.001). There was a corresponding cycle in the growth and moulting of the wool in the HPD rams consistent with a biological response to the photoperiodically-induced changes in the secretion of prolactin. The diurnal rhythm in the blood concentrations of prolactin was absent in the HPD rams, but there was a normal rhythm in the secretion of melatonin. The treatment of the animals with constant-release implants of melatonin under long days caused a marked decrease in the blood concentrations of prolactin in both the HPD and control rams. The overall conclusion is that the endogenously generated daily melatonin signal which encodes daylength acts directly in the pituitary gland to mediate the effects of photo-period on the secretion of prolactin. The photo-period transduction pathway thus by-passes the hypothalamus.
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PMID:Photoperiodically-induced cycles in the secretion of prolactin in hypothalamo-pituitary disconnected rams: evidence for translation of the melatonin signal in the pituitary gland. 792 May 91


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