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

A 46-year-old man with known arterial hypertension for 10 years had, over the last two years, developed increasing obesity, particularly of the trunk, with other symptoms typical of Cushing's syndrome. Hormone analysis demonstrated hypercortisolism and decreased plasma ACTH concentration. The dexamethasone inhibition test failed to show any significant suppression of serum cortisol. Plasma ACTH was not increased in the corticotrophin-releasing hormone and the metyrapone tests. In the short ACTH test there was an excessive cortisol increase. Abdominal computed tomography revealed both adrenals to be enlarged (6 x 4 cm) and coarsely nodular. Adrenolytic treatment with ketoconazole (400 mg daily) caused symptoms of adrenal insufficiency, but a reduced dosage of 200 mg daily lowered the cortisol level to between 5 and 11 micrograms/dl and normalized the blood pressure and clinical signs of Cushing's syndrome disappeared. Subsequent bilateral adrenalectomy confirmed the diagnosis of massive macronodular adrenal hyperplasia. Substitution treatment with twice daily 25 mg cortisone acetate and 0.05 mg fludrocortisone was started postoperatively.
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PMID:[Bilateral massive macronodular adrenal gland hyperplasia. A rare cause of Cushing's syndrome]. 830 53

Sequential cleavage of the precursor protein pre-pro-opiomelanocortin (POMC) generates the melanocortin peptides adrenocorticotrophin (ACTH), melanocyte-stimulating hormones (MSH) alpha, beta and gamma as well as the opioid-receptor ligand beta-endorphin. While a few cases of isolated ACTH deficiency have been reported (OMIM 201400), an inherited POMC defect has not been described so far. Recent studies in animal models elucidated a central role of alpha-MSH in the regulation of food intake by activation of the brain melanocortin-4-receptor (MC4-R; refs 3-5) and the linkage of human obesity to chromosome 2 in close proximity to the POMC locus, led to the proposal of an association of POMC with human obesity. The dual role of alpha-MSH in regulating food intake and influencing hair pigmentation predicts that the phenotype associated with a defect in POMC function would include obesity, alteration in pigmentation and ACTH deficiency. The observation of these symptoms in two probands prompted us to search for mutations within their POMC genes. Patient 1 was found to be a compound heterozygote for two mutations in exon 3 (G7013T, C7133delta) which interfere with appropriate synthesis of ACTH and alpha-MSH. Patient 2 was homozygous for a mutation in exon 2 (C3804A) which abolishes POMC translation. These findings represent the first examples of a genetic defect within the POMC gene and define a new monogenic endocrine disorder resulting in early-onset obesity, adrenal insufficiency and red hair pigmentation.
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PMID:Severe early-onset obesity, adrenal insufficiency and red hair pigmentation caused by POMC mutations in humans. 962 Jul 71

Pro-opiomelanocortin (POMC) is the precursor of melanocortins (adrenocorticotropin: ACTH, beta-endorphin, beta-lipotropin: beta-LPH, corticotropin like intermediate peptide, alpha-, beta- and gamma-melanocyte-stimulating hormone: alpha-, beta- and gamma-MSH) some of which act in the brain to reduce food intake and are potential mediators of leptin action. Recently, three different mutations in the POMC gene (POMC) were identified in two unrelated children that lead to early-onset extreme obesity, adrenal insufficiency, and red hair pigmentation. In the present study we systematically screened the coding region of POMC in 96 extremely obese children and adolescents, 60 healthy underweight individuals and 46 patients with anorexia nervosa (AN) and identified several variants. a) A 9 and an 18 base pair insertion (9bp and 18bp: AGC AGC GGC and AGC AGC GGC AGC AGC GGC, respectively, between codon 73 and 74; 1,2). These in-frame variants lead to the insertion of three or six amino acids (Ser-Ser-Gly; Ser-Ser-Gly-Ser-Ser-Gly) carboxy-terminal to gamma-MSH. Frequencies of the 9bp insertion allele varied between 3 and 5% among the different study groups (Pearson's chi2 P>0.5). b) Both an out-of-frame 6 bp insertion (within codon 176: GGG CCC) leading to the insertion of two amino acids (Arg-Ala) and a premature stop-codon (G-7316-T: Glu-180-Stop) within the gamma-LPH sequence were maternally inherited in an obese female proband. This proband inherited another missense mutation from her father (Glu-188-Gly). c) A missense mutation (G-7016-A; Asp-80-Asn) was observed in a single patient with AN who also harboured the 9bp insertion on a paternally derived haplotype. d) The allelic co-occurence of two silent mutations (C-6982-T and C-7285-T) was detected in two obese subjects. e) Two further silent mutations (C-3832-T; C-7111-G) were detected in an underweight and an obese subject, respectively. We conclude that the POMC gene harbors several different polymorphisms and mutations, none of which can readily be associated with the phenotypes under study.
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PMID:Systematic mutation screening of the pro-opiomelanocortin gene: identification of several genetic variants including three different insertions, one nonsense and two missense point mutations in probands of different weight extremes. 976 93

Hormone-sensitive lipase (HSL) is known to mediate the hydrolysis not only of triacylglycerol stored in adipose tissue but also of cholesterol esters in the adrenals, ovaries, testes, and macrophages. To elucidate its precise role in the development of obesity and steroidogenesis, we generated HSL knockout mice by homologous recombination in embryonic stem cells. Mice homozygous for the mutant HSL allele (HSL-/-) were superficially normal except that the males were sterile because of oligospermia. HSL-/- mice did not have hypogonadism or adrenal insufficiency. Instead, the testes completely lacked neutral cholesterol ester hydrolase (NCEH) activities and contained increased amounts of cholesterol ester. Many epithelial cells in the seminiferous tubules were vacuolated. NCEH activities were completely absent from both brown adipose tissue (BAT) and white adipose tissue (WAT) in HSL-/- mice. Consistently, adipocytes were significantly enlarged in the BAT (5-fold) and, to a lesser extent in the WAT (2-fold), supporting the concept that the hydrolysis of triacylglycerol was, at least in part, impaired in HSL-/- mice. The BAT mass was increased by 1.65-fold, but the WAT mass remained unchanged. Discrepancy of the size differences between cell and tissue suggests the heterogeneity of adipocytes. Despite these morphological changes, HSL-/- mice were neither obese nor cold sensitive. Furthermore, WAT from HSL-/- mice retained 40% of triacylglycerol lipase activities compared with the wild-type WAT. In conclusion, HSL is required for spermatogenesis but is not the only enzyme that mediates the hydrolysis of triacylglycerol stored in adipocytes.
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PMID:Targeted disruption of hormone-sensitive lipase results in male sterility and adipocyte hypertrophy, but not in obesity. 1063 13

The recent discovery of the contribution of proopiomelanocortin (POMC)-derived peptides to the regulation of energy homeostasis and exocrine gland secretion in mice aroused new interest in the complex function of the endocrine POMC network. In addition, the first mutations in the gene encoding POMC have been identified in two patients affected by adrenal insufficiency, early onset severe obesity and red hair pigmentation. Therefore, the focus of this brief review will be the detailed discussion of the implications of these new findings in the physiology of the human POMC ligand-receptor system.
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PMID:Implications of proopiomelanocortin (POMC) mutations in humans: the POMC deficiency syndrome. 1065 1

Classic Cushing's syndrome is a rare disease with an estimated incidence of 1 case per 100,000 persons. With routine use of imaging techniques such as ultrasound and CT, adrenal masses are being detected with increased frequency. A substantial percentage of these incidentalomas are hormonally active, with 5% to 20% of the tumors producing glucocorticoids. Autonomous glucocorticoid production without specific signs and symptoms of Cushing's syndrome is termed subclinical Cushing's syndrome. With an estimated prevalence of 79 cases per 100,000 persons, subclinical Cushing's syndrome is much more common than classic Cushing's syndrome. Depending on the amounts of glucocorticoids secreted by the tumor, the clinical spectrum ranges from slightly attenuated diurnal cortisol rhythm to complete atrophy of the contralateral adrenal gland with lasting adrenal insufficiency after unilateral adrenalectomy. Patients with subclinical Cushing's syndrome lack the classical stigmata of hypercortisolism but have a high prevalence of obesity, hypertension, and type 2 diabetes. All patients with incidentally detected adrenal masses scheduled for surgery must undergo testing for subclinical Cushing's syndrome to avoid postoperative adrenal crisis. The best screening test to uncover autonomous cortisol secretion is the short dexamethasone suppression test. Because the adrenal origin of a pathologic cortisol secretion is anticipated, the author prefers a higher dexamethasone dose (3 mg instead of 1 mg) to reduce false-positive results. A suppressed serum cortisol level of less than 3 micrograms/dL (80 nmol/L) after dexamethasone excludes significant cortisol secretion by the tumor. A serum cortisol level greater than 3 micrograms/dL requires further investigation, including confirmation by high-dose dexamethasone (8 mg) suppression testing, a CRH test, and analysis of diurnal rhythm. Determination of urinary free cortisol is less useful because increased values are a late finding usually associated with emerging clinical signs of Cushing's syndrome. Patients with suppressed plasma ACTH in response to CRH generally have adrenal insufficiency after surgery and require adequate perioperative and postoperative substitution therapy. Whether patients with subclinical Cushing's syndrome should undergo adrenalectomy is a matter of debate. The author performs surgery in young patients (< 50 years), in patients with suppressed plasma ACTH, and in patients with a recent history of weight gain, substantial obesity, arterial hypertension, diabetes mellitus, and osteopenia. In completely asymptomatic patients with normal plasma ACTH concentrations and in patients older than 75 years, the author recommends a nonsurgical approach. A large prospective randomized study is necessary to evaluate the benefits of surgery versus conservative treatment in patients with subclinical Cushing's syndrome.
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PMID:Subclinical Cushing's syndrome. 1073 63

The cloning of five rodent obesity genes has constituted a major advance in our understanding of body weight homeostasis. Breakthroughs in human molecular genetics have identified mutations disrupting either rodent homologue/analogue genes or genes involved in the same pathways in obese patients. Three rare cases of human morbid obesity of early onset associated with hypogodatropic hypogodanism are due to mutations in the leptin and the leptin receptor genes. These studies have confirmed that leptin plays not only a crucial role in the control of body weight in the human but also in several endocrine functions. Other Human obesity syndromes are linked to mutations in the genes encoding brain-expressed targets of leptin, particularly some key components of the melanocortin system. Patients compound heterozygous for mutations in the POMC gene display severe obesity of early onset, congenital adrenal insufficiency and red hair. Another genetic cause of obesity is due to mutation in the Proconvertase gene (PC1), the enzyme required for the cleavage of POMC into ACTH and alpha MSH, and also of Proinsulin to insulin. The subject compound heterozygous for the PC1 mutation displays besides obesity, a partial ACTH deficiency, elevated POMC and late post absorptive hypoglycemia due to the accumulation of high pro-insulinemia. Contrasting largely with these rare syndromic forms of obesity, several mutations located in the melanocortin 4 receptor gene have been showed to cause an early onset dominant form of obesity with no other associated abnormalities indifferent populations. These mutations in MC4-R could represent a "frequent" cause of common monogenic forms of obesity in human. More generally, these researches into human obesity have opened new exciting understandings in some of the pathways regulating body fat mass.
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PMID:[Monogenic forms of obesity: from mice to human]. 1114 35

In peripheral tissues, corticosteroid hormone action is determined, in part, through the activity of 11beta-hydroxysteroid dehydrogenases (11beta-HSD), two isozymes of which interconvert hormonally active cortisol (F) and inactive cortisone (E). 11beta-HSD type 2 (11beta-HSD2) inactivates F to E in the kidney, whilst 11beta-HSD type 1 (11beta-HSD1) principally performs the reverse reaction activating F from E in the liver and adipose tissue. Alteration in expression of these 11beta-HSD isozymes in peripheral tissues modifies corticosteroid action: loss of 11beta-HSD2 activity in the kidney results in cortisol-induced mineralocorticoid excess, and loss of hepatic 11beta-HSD1 activity improves insulin sensitivity through a reduction in cortisol-induced gluconeogenesis and hepatic glucose output. Conversely, overexpression of 11beta-HSD1 in omental adipose tissue can stimulate glucocorticoid-induced adipocyte differentiation which may lead to central obesity. Patients with hypopituitarism have many clinical features in common with patients with Cushing's syndrome--notably visceral obesity, insulin resistance, osteoporosis and increased vascular mortality. Our hypothesis was that many of these features may be explained by an effect of growth hormone (GH) on the 11beta-HSD isozymes. As assessed by urinary free cortisol/urinary free cortisone ratios and endorsed through in vitro studies, neither GH nor insulin-like growth factor (IGF)-I affect 11beta-HSD2 activity. Patients with acromegaly show a reduction in hepatic-derived metabolites of cortisol/cortisone - levels return to normal when GH concentrations are normalized. Conversely, patients with GH deficiency in the setting of hypopituitarism demonstrate an increased cortisol/cortisone metabolite ratio and reduction in circulating cortisol concentrations in patients on hydrocortisone replacement. Treatment with low-dose GH replacement reverses these abnormalities. These clinical data suggest that GH (and/or IGF-I) inhibits 11beta-HSD1 (i.e. E to F conversion) (parallel in vitro studies suggest that IGF-I and not GH inhibits 11beta-HSD1). These findings have important clinical ramifications. Firstly, the GH-mediated increase in cortisol metabolism (mediated via reduced E to F conversion) may precipitate adrenal insufficiency in hypopituitary patients with partial adrenocorticotropic hormone deficiency commencing GH therapy. Secondly, many of the phenotypic features of hypopituitarism can be explained by an alteration in 11beta-HSD1 activity: GH deficiency effectively increases cortisol production in key target tissues including liver and adipose tissue, promoting insulin resistance and visceral adiposity. Thirdly, the reported beneficial effects of GH on cardiovascular risk factors in patients with hypopituitarism may be an indirect effect via alterations in cortisol metabolism. Finally, the GH/IGF-I modulation of cortisol metabolism may underpin the pathogenesis of common diseases such as central obesity and idiopathic osteoporosis. Patients with central obesity but with no evidence of hypopituitarism have relative GH deficiency and it is exciting to speculate that low-dose GH treatment in this group, by inhibiting cortisol generation within omental fat, may offer a novel therapeutic approach.
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PMID:Growth hormone, insulin-like growth factor-I and the cortisol-cortisone shuttle. 1178 77

Central hypothyroidism (CH) is a rare cause of hypothyroidism, generally due to either pituitary or hypothalamic defects. On the basis of its etiology, it is possible to distinguish acquired and hereditary forms. Hereditary CH can be isolated or associated with combined pituitary hormone deficiency (CPHD). In the former case, alterations of only two genes, TSHbeta and the TRH receptor, have so far been described as responsible for the disorder. In hereditary CH associated with CPHD, inactivating mutations of different pituitary transcription factors (HESX1, PROP-1, POU1F1) have been found involved in the pathogenesis of the disease. Finally, an association between CH and severe obesity has been described in patients with leptin receptor (Leptin-R) mutations. The clinical consequences of CH in adult life vary greatly depending on the etiology, the severity of the thyroid impairment, the extent of the associated hormone deficiencies, and the age of the patient at the time of the onset of the disease. In general, acquired CH is less severe than the congenital form because of the constitutive activity of the wild-type TSH-receptor. Symptoms and signs of thyroid insufficiency are usually milder than those of primary hypothyroidism, and goiter is always absent. In CPHD, most patients have other endocrine manifestations of the disease (growth failure, delayed puberty, adrenal insufficiency, diabetes insipidus) that lead them to seek medical attention before the hypothyroidism becomes severe. Early diagnosis of the congenital form by neonatal screening for hypothyroidism is strongly recommended in order to avoid cretinism. Replacement therapy with L-thyroxine administration has to be established as soon as possible.
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PMID:Central hypothyroidism: consequences in adult life. 1196 21

The functional loss of both alleles of the human pro-opiomelanocortin (POMC) gene leads to a very rare syndrome of hypoadrenalism, red hair and early-onset obesity. In order to examine whether more subtle genetic variants in POMC might contribute to early-onset obesity, the coding region of the gene was sequenced in 262 Caucasian subjects with a history of severe obesity from childhood. Two children were found to be heterozygous for a missense mutation, R236G, which disrupts the dibasic cleavage site between beta melanocyte-stimulating hormone (beta-MSH) and beta-endorphin. Beta-TC3 cells transfected with the mutant POMC cDNA produced a mutant beta-MSH/beta-endorphin fusion protein. This fusion protein bound to the human melanocortin-4 receptor (hMC4R) with an affinity similar to its natural ligands, but had a markedly reduced ability to activate the receptor. This variant co-segregated with early-onset obesity over three generations in one family and was absent in 412 normal weight UK Caucasian controls. Combining the results in UK Caucasians with a new case-control study in French subjects and three previously published reports, mutations disrupting this processing site were present in 0.88% of subjects with early-onset obesity and 0.22% of normal-weight controls. These results suggest that the R236G mutation may confer an inherited susceptibility to obesity through the production of an aberrant fusion protein that has the capacity to interfere with central melanocortin signalling.
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PMID:A missense mutation disrupting a dibasic prohormone processing site in pro-opiomelanocortin (POMC) increases susceptibility to early-onset obesity through a novel molecular mechanism. 1216 61


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