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

Brown adipose tissue (BAT) thermogenesis is important in the adaptation of body energy expenditure to cold exposure, fasting, and overfeeding and in the pathogenesis of obesity. Thyroid hormones are required for the normal functioning of BAT. The mechanism of their effect on BAT, however, has not yet been elucidated. Since most thyroid hormone effects are mediated via the binding of T3 to nuclear receptors (NT3R) the present studies were performed to investigate whether BAT contained NT3R and whether these NT3R were affected by cold exposure, fasting, overfeeding, or hypo- or hyperthyroidism. Rat BAT was found to contain NT3R with a maximum binding capacity (MBC) of 0.28 ng T3/mg DNA and a dissociation constant (Kd) of 3.2 X 10(-10) M. These parameters were unaffected by any of the experimental conditions studied. A major alteration of BAT NT3R MBC or Kd is thus not a causal factor in the changes in BAT thermogenesis induced by the above experimental conditions. In contrast, 3-wk overfeeding increased (+48%) and fasting decreased (-29%) the MBC of hepatic NT3R. Overfeeding increased serum T3 (+110%), while fasting decreased it (-37%).
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PMID:Brown fat nuclear triiodothyronine receptors in rats. 377 60

Obese (ob/ob) mice exhibit reduced adaptive thermogenesis associated with an impairment of thyroid hormone action. The mechanism underlying the latter defect was investigated by comparing the binding characteristics and occupancy of solubilized nuclear 3,5,3'-triiodothyronine (T3) receptors from livers of lean and obese mice. Scatchard analysis showed minimal differences in Bmax and Kd between phenotypes at both 4 and 8-10 wk of age, indicating that reduced hepatic thyroid hormone expression in obese mice is not caused by alterations in nuclear receptor concentration or affinity. In contrast, nuclear T3 receptor occupancy (endogenous T3 associated with the specific receptor divided by Bmax) was 14 and 23% lower in 4- and 8- to 10-wk-old obese mice, respectively. Together with reported changes in hepatic thyroid hormone-sensitive enzymes, these data are consistent with a diminished nuclear T3 signal initiating thyroid hormone action in obese mice. Decreased nuclear T3 receptor occupancy may be secondary to a low transport of plasma T3 to the nuclear pool. In conclusion, impaired hepatic thyroid hormone action in obese mice is mediated in part at least by a reduction in nuclear T3 receptor occupancy.
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PMID:Nuclear triiodothyronine receptor binding characteristics and occupancy in obese (ob/ob) mice. 382 66

The presence of obesity, defined as weight 20 per cent or more above ideal body weight or increased body fat content, significantly increases risk of pulmonary, cardiovascular, metabolic, and gastrointestinal problems. Obesity is a major cause of shortened life expectancy. While obesity is not essential for the development of the obstructive sleep apnea syndrome, a significant percentage of patients with obstructive sleep apnea are obese. When evaluating these patients who have obstructive sleep apnea, it is important to search diligently for medical problems that are commonly found among the obese. While there is an increased incidence of obese patients among those who have obstructive sleep apnea, the exact reason for this is uncertain. The study of endorphins and enkephalins may expand our understanding of obesity, ventilatory regulation, and obstructive sleep apnea. This may, in fact, enable us to understand better the interrelationship between obesity and obstructive sleep apnea. The role that thyroid hormone, testosterone, and progesterone play in obstructive sleep apnea has also been reviewed. Patients who have obstructive sleep apnea should not be treated with testosterone. All patients given testosterone should be observed quite closely for the possible signs and symptoms of obstructive sleep apnea. Progesterone seems to be of some help in patients who have obesity hypoventilation syndrome. Its effectiveness in patients with obstructive sleep apnea is less clear. The obesity hypoventilation syndrome as described by Burwell is relatively uncommon. Many of the manifestations of the obesity hypoventilation syndrome, however, are found in patients with obstructive sleep apnea. The recognition that the symptoms stem from underlying obstructive sleep apnea offers great potential for therapy. Weight reduction is valuable therapy for patients with obesity and pulmonary dysfunction, obesity and obstructive sleep apnea, and obesity hypoventilation syndrome. Weight reduction and weight maintenance, while difficult, are essential in patients with obesity, obesity and obstructive sleep apnea, and the hypoventilation syndrome. Obesity should be viewed as a medical problem deserving medical attention and long-term medical follow-up.
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PMID:Obesity and hormonal factors in sleep and sleep apnea. 390 3

This report reveals a surprisingly high incidence of thyroid hormone (T3 and T4) autoantibodies (THA) and thyroglobulin autoantibodies in a closed flock of untreated Cornell strain (CS) White Leghorn chickens. This flock is closely related to the Obese strain chicken, which develops a severe spontaneous autoimmune thyroiditis. A sensitive electrophoretic autoradiographic assay for THA was developed. This assay was applied to the study of autoantibodies to T3 and T4 in the sera of adult female CS chickens. Of 109 females, 29.4% had antibodies to T3 and 18.4% had antibodies to T4. The incidence of thyroglobulin antibodies, determined by passive hemagglutination, was 15.6%. The presence of THA affected RIA measurements because serum T3 and T4 hormone concentrations appeared elevated in those birds with moderate to high antibody levels. There was major variance in the electrophoretic heterogeneity of the THA from individual chickens; i.e., some of the sera contained antibodies to T3 or T4 that appeared to be monoclonal, whereas other sera exhibited polyclonal multi-banded patterns. To determine if antibodies reactive with T3 and T4 (which are haptens) were generated by antibody responses to the T3/T4 sites on the thyroglobulin molecule, competitive binding assays were performed to determine the relative binding affinities of the antibodies for the haptens (T3/T4) and the "hapten-conjugate" (thyroglobulin). In these assays, thyroglobulin competed with the haptens, thus supporting the above hypothesis.
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PMID:Analysis of triiodothyronine and thyroxine-binding autoantibodies in chickens susceptible to autoimmune thyroiditis. 398 98

Obese (ob/ob) mice exhibit impaired cold- and diet-induced thermogenesis, which may result in part from a defect in thyroid hormone action at the level of peripheral deiodination of thyroxine (T4) to 3,5,3'-triiodothyronine (T3). The latter possibility was examined by comparing kinetic parameters of 5'-deiodination (5'-D) in hepatic and renal microsomes of lean and obese mice during various physiological conditions. 5'-D Was adaptive to changes in age (1 to 8-10 wk), environmental temperature (14, 25, and 33 degrees C), and thyroid hormone status in both lean and obese mice. The magnitude of enzyme response, however, varied between phenotypes. 5'-D Response to age and environmental temperature was also dependent on tissue type, indicating that different isozymes for 5'-D may exist in liver and kidney. Under basal conditions at 25 degrees C, maximal hepatic and renal 5'-D was lower in obese mice than in lean mice. Differences in Vmax were observed as early as 1 wk of age. Km values for 5'-D were similar in lean and obese mice. These findings suggest that T3 availability to thermogenic target tissues may be impaired in obese mice, which may contribute to diminished thyroid hormone expression and heat production in these animals.
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PMID:Regulation of iodothyronine 5'-deiodination in lean and obese (ob/ob) mice. 402 42

A predominantly upper-middle-class white population of 279 men and 345 women with an average age of 66 years was evaluated to determine correlates of high- and low-density lipoprotein cholesterol (HDL and LDL), since these may be the only cholesterol measurements predictive of cardiovascular disease after age 50. Associations of HDL and LDL with age, alcohol use, obesity, smoking, diet, exercise, and medication use were examined using multiple linear regression. Alcohol, average and above-average exercise, postmenopausal estrogen use (women), B vitamin intake, and corticosteroid use were all positively related to HDL levels, and obesity (men only), cigarette smoking, and thyroid hormone use were inversely related. The only statistically significant correlates of LDL were an increase with age (women only) and lower levels in women using thyroid hormone. However, the associations of several behavioral variables with LDL, although not statistically significant, were in the expected direction. These results may suggest the continuing potential for preventive intervention even in an elderly population.
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PMID:High- and low-density lipoprotein cholesterol: correlates in an older population. 404 78

In order to assess insulin sensitivity for glucose utilization in the other type of diabetes, insulin sensitivity tests were performed in subjects with pancreatitis, liver disease, steroid treatment and hyperthyroidism. Insulin sensitivity for glucose utilization decreased in subjects with liver disease, steroid treatment and hyperthyroidism irrespective of the presence or absence of glucose intolerance. Hyperinsulinism was associated in most of the subjects with liver disease and steroid treatment, but even in normo-insulinemic subjects, insulin insensitivity was observed. Obesity was associated with only 2 cases in both pancreatitis and liver diseases and therefore was excluded as a major cause for insulin insensitivity in subjects studied. In subjects with pancreatitis, insulin sensitivity was not significantly decreased. It is to be noted that 4 out of 5 subjects with diabetic OGTT (oral glucose tolerance test) exhibited normal insulin sensitivity. The results indicate that in pancreatitis, tissue insulin sensitivity for glucose metabolism is not altered and therefore can be used as a marker to differentiate the other type of diabetes due to pancreatitis from type 1 or 2 diabetes. Although hyperinsulinemia may be attributable to insulin insensitivity in subjects studied at least in part, steroid and thyroid hormone are thought to act directly antagonistically with insulin for glucose metabolism.
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PMID:Insulin sensitivity in pancreatitis, liver diseases, steroid treatment and hyperthyroidism assessed by glucose, insulin and somatostatin infusion. 614 89

Obese patients taking a 1.34 MJ/day formula diet showed a steady decline in the rate of weight loss after several weeks and this was associated with a fall in RMR, serum T3 levels and the number of T3 receptors on peripheral lymphocytes. The addition of T3 (60 micrograms/day) to the dietary regime produced a significantly greater weight loss by the 12th week. Analysis of individual thyroid hormone levels revealed those patients taking the T3 tablets who achieved the greatest weight loss had the lowest serum T3 levels but the greatest suppression of serum T4 values. The serum T3 levels in the T3 treated subjects were negatively correlated with the lymphocyte rece 12th week. Analysis of individual thyroid hormone levels revealed those patients taking the T3 tablets who achieved the greatest weight loss had the lowest serum T3 levels but the greatest suppression of serum T4 values. The serum T3 levels in the T3 treated subjects were negatively correlated with the lymphocyte rece 12th week. Analysis of individual thyroid hormone levels revealed those patients taking the T3 tablets who achieved the greatest weight loss had the lowest serum T3 levels but the greatest suppression of serum T4 values. The serum T3 levels in the T3 treated subjects were negatively correlated with the lymphocyte receptor capacity. It is postulated that the fall in the number of T3 receptors is the primary event leading to the observed serum hormone level changes in the T3-treated patients.
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PMID:The role of T3 and its receptor in efficient metabolisers receiving very-low-calorie diets. 626 57

Severe thyroid atrophy was found at the autopsy of a 39-year-old white woman who died of myocarditis, probably of viral etiology. Prolonged ingestion of thyroid hormone for the treatment of obesity appears to be the only plausible explanation for the atrophy, secondary to suppression of the pituitary thyrotrope.
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PMID:Severe thyroid atrophy due to prolonged ingestion of thyroid hormone for treatment of obesity. 670 2

Pharmacologic doses of thyroid hormones were administered chronically in diets and acutely by injection to determine their metabolic effects on the development of obesity and the response to cold stress in genetically obese mice. Feeding a 0.1% thyroid powder (TP) diet for 6 weeks to weanling male mice resulted in a marked reduction in weight gain and high mortality in obese but not in non-obese mice. Diets containing 0.01 and 0.02% TP also produced enhanced effects in obese mice during a 13-week feeding period as indicated by reduced body weight, fat and protein and reduced blood glucose at ambient temperature. Both acute and chronic treatment with thyroid hormone produced similar effects in the cold (4 degrees). Blood glucose concentrations were reduced in both obese and non-obese mice, but blood free fatty acid values were unchanged due to hormone treatment. Neither acute nor chronic treatment with thyroid hormones prolonged survival of obese mice during cold exposure. These results suggest a normal or enhanced fat mobilization and utilization in response to exogenous thyroid hormone at ambient temperature. However, the defect in utilization of energy stores for thermogenesis during cold exposure was not ameliorated by this treatment.
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PMID:Influence of thyroid hormone treatment on growth, body composition and metabolism during cold stress in genetically obese mice. 698 55


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