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

A tryptophan to arginine (Trp64Arg) mutation in the beta 3-adrenergic receptor (beta 3-AR) gene has been implicated in diabetes and obesity. We investigated the relationship of the beta 3-AR gene mutation with total body weight, BMI, central abdominal fat, blood pressure (BP), and reproductive history in 686 elderly subjects (429 women, 257 men; mean age 69.8 +/- 6.9 [+/-SD] years) from a cross section of a normal population in Australia. About 14% of the test population were heterozygote carriers of the Trp64Arg mutation; however, significant effects on clinical parameters were only observed in women. The frequency of the mutation was significantly increased in obese women compared with lean women (BMI > or = 27: 20% compared with BMI < 27: 11%, P = 0.02). Significantly higher total body weight (67.5 +/- 12.9 vs. 64.1 +/- 12.2 kg, P = 0.03) and BMI (26.3 +/- 4.7 vs. 25.1 +/- 4.5 kg/m2, P = 0.03) was observed in heterozygote women compared with normal subjects (homozygous for tryptophan). Central abdominal fat was not significantly different, except in women under 70 years, where heterozygotes had 16% higher abdominal fat compared with normal subjects. Female heterozygotes had significantly higher diastolic BP, even after adjustment for age and BMI (88.9 +/- 11.1 vs. 84.2 +/- 10.8 mmHg, P = 0.003) and a longer reproductive life, with an earlier menarche (12.8 +/- 1.3 vs. 13.4 +/- 1.5 years, P = 0.006), a higher gravidity (4.4 +/- 2.4 vs. 3.5 +/- 2.1, P = 0.01), and higher parity (3.8 +/- 2.0 vs. 3.0 +/- 1.9, P = 0.005). Clearly, the beta 3-AR mutation has pleiotrophic effects on a number of physiological systems, including BMI, BP, and reproductive history, perhaps suggesting evolutionary reasons for its maintenance in the population.
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PMID:The beta 3-adrenergic receptor gene Trp64Arg mutation is overrepresented in obese women. Effects on weight, BMI, abdominal fat, blood pressure, and reproductive history in an elderly Australian population. 882 71

Prompted by the recent findings that a tryptophan to arginine (Trp64Arg) mutation in the beta3-adrenergic receptor gene was associated with an earlier onset of non-insulin-dependent diabetes mellitus (NIDDM) in Pima Indians, with abdominal obesity and insulin resistance in Finns, and with an increased capacity to gain weight in French whites, we studied the prevalence of this mutation in 231 diabetic and 95 nondiabetic Japanese subjects and assessed its contribution to the development of obesity and NIDDM. The allelic frequencies of the mutation were 0.18 in diabetic and 0.23 in nondiabetic subjects, showing no significant difference between the two groups (P = .067). In nondiabetic subjects, body mass index (BMI) did not differ between those with and without the mutation (22.2 +/- 3.5 v 21.4 +/- 3.2 kg/m2, P = .252). In NIDDM subjects, BMI at the time of study and maximal BMI before the start of treatment did not differ between those with and without the mutation (22.8 +/- 2.6 v 23.2 +/- 3.7 kg/m2, P = .678, and 24.7 +/- 2.6 v 24.9 +/- 3.1 kg/m2, P = .277). Homozygotes for the mutation did not have trends to have increased BMI in either diabetic or nondiabetic subjects. The age at diagnosis of NIDDM also did not differ between the two groups (48.8 +/- 9.9 v 47.8 +/- 12.5 years, P = .796). Fasting serum cholesterol and triglyceride levels and systolic and diastolic blood pressure before the start of treatment did not differ between NIDDM subjects with and without the mutation. In conclusion, although the Trp64Arg mutation is not uncommon in Japanese, it does not appear to be associated with obesity, NIDDM, age at diagnosis of NIDDM, or dyslipidemia. Our results suggest that the mutation has minor effects, if any, on the development of obesity and NIDDM in Japanese.
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PMID:Prevalence of the Trp64Arg missense mutation of the beta3-adrenergic receptor gene in Japanese subjects. 903 Aug 29

A Trp64Arg variant in the human beta 3-adrenoceptor is associated with earlier onset of non-insulin-dependent diabetes mellitus and obesity in several populations. The present study investigated in vivo lipolysis in individuals homozygous for the 'variant' allele coding for arginine (Arg) in position 64 of the beta 3-adrenoceptor or homozygous for the 'wild type' tryptophan (Trp) allele. Subjects were 25 healthy, non-diabetic Pima Indians, 8 Arg (2 males, 6 females; aged 34 +/- 9 years, BMI 36.2 +/- 7.7 kg/m2, 43 +/- 11% body fat [mean +/- SD]), and 17 Trp (9 males, 8 females; aged 30 +/- 5 years, BMI 30.4 +/- 6.1 kg/m2, 39 +/- 9% body fat). After an overnight fast, a microdialysis probe was inserted in the subcutaneous adipose tissue and perfused with Ringer's solution. Dialysate was collected in 10-min fractions during a 30-min baseline and during 40 min with isoproterenol, a non-selective beta-adrenergic agonist, added to the perfusate (1 mumol/l). Changes in rate of lipolysis were assessed as changes in dialysate glycerol concentration. The relative changes in dialysate glycerol concentrations in response to isoproterenol, expressed as percent over baseline, were similar in the two groups (i.e. 63 +/- 30 and 74 +/- 28% in the Arg and Trp subjects, respectively). The results were also similar in the two groups after adjustment for sex and percentage of body fat. No differential effect of isoproterenol on blood flow was demonstrated between the two groups (assessed by the ethanol dilution technique). These results are consistent with in vitro studies showing no functional effect of the beta 3-adrenoceptor variant, and/or indicate that the beta 3-adrenoceptor is not very important for subcutaneous adipose tissue lipolysis.
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PMID:No effect of the Trp64Arg beta 3-adrenoceptor variant on in vivo lipolysis in subcutaneous adipose tissue. 924 6

The beta3 adrenergic receptor, located on chromosome 8, is a regulator of energy expenditure and lipolysis. A missense mutation in this gene, characterized by the replacement of tryptophan by arginine at codon 64 (Trp64Arg), is associated with obesity in some studies. We examined the effect of this variant on obesity in Mexican Americans, using a paired sibling design to minimize variability due to genetic background and a previously identified major susceptibility locus for obesity. We identified 45 sib-pairs that were concordant (identical by descent) for a locus on chromosome 2 which we have shown previously to be tightly linked to obesity in this population. The Trp64Arg variant, detected by PCR-restriction fragment length polymorphism analysis, was present in one sibling within each of the 45 sib-pairs. Presence of the variant was associated with significantly higher values in body mass index (P = 0.04), fat mass (P = 0.04), and waist circumference (P = 0.05). We conclude that the Trp64Arg variant is associated with obesity in this Mexican American population. The paired sibling design probably enhanced our ability to detect the effects of this variant by allowing us to account for variation attributable to another obesity susceptibility locus and to background genes.
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PMID:A paired sibling analysis of the beta-3 adrenergic receptor and obesity in Mexican Americans. 944 91

Albright hereditary osteodystrophy (AHO), a disorder characterized by skeletal abnormalities and obesity, is associated with heterozygous inactivating mutations in the gene for Gsalpha. A novel Gsalpha mutation encoding the substitution of tryptophan for a nonconserved arginine within the switch 3 region (Gsalpha R258W) was identified in an AHO patient. Although reverse transcription-polymerase chain reaction studies demonstrated that mRNA expression from wild type and mutant alleles was similar, Gsalpha expression in erythrocyte membranes from the affected patient was reduced by 50%. A Gsalpha R258W cDNA, as well as one with arginine replaced by alanine (Gsalpha R258A), was generated, and the biochemical properties of in vitro transcription/translation products were examined. When reconstituted with cyc- membranes, both mutant proteins were able to stimulate adenylyl cyclase normally in the presence of guanosine- 5'-O-(3-thiotriphosphate) (GTPgammaS) but had decreased ability in the presence of isoproterenol or AlF4- (a mixture of 10 microM AlCl3 and 10 mM NaF). The ability of each mutant to bind and be activated by GTPgammaS or AlF4- was assessed by trypsin protection assays. Both mutants were protected normally by GTPgammaS but showed reduced protection in the presence of AlF4-. The addition of excess GDP (2 mM) was able to rescue the ability of AlF4- to protect the mutants, suggesting that they might have reduced affinity for GDP. A Gsalpha R258A mutant purified from Escherichia coli had decreased affinity for GDP and an apparent rate of GDP release that was 10-fold greater than that of wild type Gsalpha. Sucrose density gradient analysis demonstrated that both Gsalpha R258W and Gsalpha R258A were thermolabile at higher temperatures and that denaturation of both mutants was prevented by the presence of 0.1 mM GTPgammaS or 2 mM GDP. The crystal structure of Gsalpha demonstrates that Arg258 interacts with a conserved residue in the helical domain (Gln170). Arg258 substitutions would be predicted to open the cleft between the GTPase and helical domains, allowing for increased GDP release in the inactive state, resulting in enhanced thermolability and reduced AlF4--induced adenylyl cyclase stimulation and trypsin protection, since activation by AlF4- requires bound GDP.
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PMID:A novel mutation in the switch 3 region of Gsalpha in a patient with Albright hereditary osteodystrophy impairs GDP binding and receptor activation. 972 13

5-Hydroxytryptophan (5-HTP) is the intermediate metabolite of the essential amino acid L-tryptophan (LT) in the biosynthesis of serotonin. Intestinal absorption of 5-HTP does not require the presence of a transport molecule, and is not affected by the presence of other amino acids; therefore it may be taken with meals without reducing its effectiveness. Unlike LT, 5-HTP cannot be shunted into niacin or protein production. Therapeutic use of 5-HTP bypasses the conversion of LT into 5-HTP by the enzyme tryptophan hydroxylase, which is the rate-limiting step in the synthesis of serotonin. 5-HTP is well absorbed from an oral dose, with about 70 percent ending up in the bloodstream. It easily crosses the blood-brain barrier and effectively increases central nervous system (CNS) synthesis of serotonin. In the CNS, serotonin levels have been implicated in the regulation of sleep, depression, anxiety, aggression, appetite, temperature, sexual behaviour, and pain sensation. Therapeutic administration of 5-HTP has been shown to be effective in treating a wide variety of conditions, including depression, fibromyalgia, binge eating associated with obesity, chronic headaches, and insomnia.
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PMID:5-Hydroxytryptophan: a clinically-effective serotonin precursor. 972 88

Recent studies have suggested an association between Type II (non-insulin-dependent) diabetes mellitus-related phenotypes and a cytosine-to-thymidine substitution that results in the replacement of tryptophan by arginine at codon 64 (Trp64Arg or W64R) of the beta3-adrenergic receptor gene. Here, we present the results of possibly the largest association study to date on the variant in a sample of 526 families with a total of 1725 subjects, 1053 of whom had Type II diabetes. Preliminary calculations suggested that we had excellent power to detect the moderate associations which were reported in previous studies. No associations were found between the W64R variant and the following phenotypes in our sample: Type II diabetes, age at diagnosis for Type II diabetes, measures of obesity, fasting glucose, fasting insulin, minimal model variables, and systolic and diastolic blood pressures. In the analysis of plasma lipids, we detected an association between the variant and HDL ratios (HDL cholesterol/total cholesterol) (p = 0.013), which remained significant even after adjusting for sex, affection status and age. Since W64R homozygotes (n = 11) had the highest HDL ratios, however, heterozygotes had the lowest and the wild-type subjects had intermediate values, we conclude that the W64R variant is unlikely to reduce HDL ratios in a dose-dependent, pathogenic manner.
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PMID:The W64R variant of the beta3-adrenergic receptor is not associated with type II diabetes or obesity in a large Finnish sample. 1006 5

Recently, 5-hydroxy-L-tryptophan (5-OHTrp) has been promoted as an alternative to banned L-tryptophan as a dietary supplement. It has been claimed to help alleviate obesity, insomnia, depression, and headaches. However, eosinophilia-myalgia syndrome (EMS)-like symptoms have also been associated with ingestion or exposure to 5-OHTrp. HPLC-UV analysis of EMS-implicated 5-OHTrp revealed the presence of peak X, described as case-implicated. We show that peak X is actually a family of contaminants with the same molecular weight (234 Da) and similar HPLC retention times. We also demonstrate that all eight samples of commercially available 5-OHTrp analyzed by HPLC-MS contained three or more contaminants of the peak X family. The significance of these findings is discussed.
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PMID:Eosinophilia-myalgia syndrome case-associated contaminants in commercially available 5-hydroxytryptophan. 1072 Oct 89

Leptin is a protein produced by the ob-ob gene which inhibits food intake. Plasma levels have previously been reported to be altered in obesity and anorexia nervosa (AN) but not bulimia nervosa (BN). We measured fasting plasma leptin levels by radioimmunoassay in 53 subjects carefully studied at NIMH, including 37 women meeting DSM-III-R criteria for BN [10 with concurrent AN (body mass index (BMI)=14.1+/-1.4), 27 without AN (BMI=20.4+/-1.6)] and 16 normal control women (NCs) (BMI=21.1+/-2.0). Patients were medication-free and abstinent from bingeing and purging for three to four weeks prior to study. Plasma leptin levels were significantly correlated to BMI (r=0.41, P<0.002), weight (kg, r=0.43, P<0.001), and percent average body weight (%ABW, r=0.45, P<0.001) in the total group. Plasma leptin levels were lower in the BN subjects (3.4+/-2.5 ng/ml) compared to the NCs (6.1+/-2.6 ng/ml, P<0.001, ANCOVA) even after controlling for BMI and weight. There was no significant difference between BN subjects with AN (n=10, 2.6+/-2.6 ng/ml) and those without AN (n=27, 3.8+/-2.4 ng/ml), despite lower BMI in BN with AN. Furthermore, leptin levels were decreased in BN without AN compared with healthy controls, even though BMI was comparable in these two subgroups. Plasma leptin concentrations were negatively correlated with baseline plasma cortisol levels (n=49, r=-0.49, P<0.001) and positively correlated with prolactin responses following L-tryptophan (n=49, r=0.37, P<0.009) and m-chlorophenylpiperazine (n=52, r=0.24, P<0.09). This is the first known report of decreased plasma leptin levels in BN. The decrement in leptin concentration is not related to BMI, body weight, or the presence or absence of BN. HPA axis activation as well as serotonin dysregulation may be related to decreased leptin levels, which may in turn contribute to disinhibited eating in BN. Although current leptin levels were not correlated with self-reported previous binge frequency, the role of leptin in the pathophysiology of BN deserves further study.
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PMID:Reduced plasma leptin concentrations in bulimia nervosa. 1093 46

Epidemiological evidence links breast cancer, a typical endocrine-related tumor, with western lifestyle, in particular eating habits. Yet, it's necessary to distinguish premenopausal from postmenopausal breast cancer. Visceral obesity and body weight gain are considered responsible for the increased risk of postmenopausal breast cancer. In fact, the mammary gland is sensitive to the level of circulating estrogens, visceral obesity is usually associated with higher levels of free steroid hormones, and the adipose tissue performs important endocrine function (clearance and aromatisation of androgens, regulation of free testoterone/DHEAS molar ratio). Before menopause, ovarian polycystosis is often seen with android obesity, and breast cancer risk could arise; however, as visceral obesity is generally less frequent, genetic factors are more important than nutritional ones. Furthermore, variations have been recorded in the secretion of insulin and insulin-like growth factors, involved in the genesis of the breast cancer. High body weight and male fat distribution negatively influence prognosis of breast cancer, too; this association is linked with the presence of estrogen and progesterone receptors in tumoral cells. Links between diet quality and breast cancer risk are shown: increased use of saturated fats and animal proteins, and a consequently decreased use of vegetables, legumes and fruit, constituting the so-called Mediterranean diet, are considered responsible for the increased risk of breast cancer. Lower fat and alcohol ingestion, the use of dietary fibre and a higher use of complex carbohydrates could reduce breast cancer risk. Finally, starting from the results of our previous animal researches, we suggest using a tryptophan devoid diet for a few days for premenopausal women with male obesity and alterations to the menstrual cycle.
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PMID:Breast cancer and obesity. 1144 84


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