Expression of the beta 3-adrenoceptor gene polymorphism (Trp64Arg) in obese diabetic and non-diabetic subjects

1. A missense mutation (Trp64Arg) in the beta 3-adrenoceptor (beta 3-AR) gene has been associated with weight gain, insulin resistance and earlier-onset non-insulin-dependent diabetes mellitus (NIDDM), but the strength of these associations varies considerably between populations and the functional significance of Trp64Arg remains unclear. 2. The Trp64Arg mutation was investigated in obese NIDDM (n = 50) and obese non-diabetic (n = 53) subjects by polymerase chain reaction (PCR) amplification of genomic DNA and digestion of the 210 bp product by BstOI. The Arg allele was found in 22.3% of all subjects, but there were no homozygotes for the mutation. Non-diabetic subjects heterozygous for the mutation were more obese and Trp/Arg diabetics had a slightly younger age of onset of NIDDM (47 vs 51 years, respectively), but there were no significant differences in mutation frequency between the two groups. Metabolic parameters (e.g. fasting lipids and glycaemic control) were similar among diabetic subjects with and without the Trp64Arg mutation. 3. In conclusion, the frequency of the Trp64Arg mutation of the beta 3-AR was higher in this obese population compared with some previous studies, but there was no evidence that Trp64Arg confers an increased susceptibility to NIDDM among obese insulin-resistant subjects or that diabetics with the mutation fare worse in terms of lipid or glucose metabolism.     

Trp64Arg variant of the beta3-adrenoceptor and insulin resistance in obese postmenopausal women

There is controversy regarding the role of the Trp64Arg variant of the beta3-adrenergic receptor (beta3AR) gene in the pathogenesis of insulin resistance. The modest effect of the variant as well as differences in study design, gender, age, and genetic background may contribute to divergent results among investigations. Insulin sensitivity (euglycemic clamp and tracers) was measured in 13 obese women (57 +/- 6 yr old) heterozygous for the beta3AR variant and in 14 women (57 +/- 4 yr old) homozygous for the normal gene. Groups were matched for age, body composition, intraabdominal fat, sc abdominal fat, physical activity level, and aerobic capacity. Exogenous glucose infusion during the clamp was significantly lower (P = 0.03) in beta3AR heterozygotes (241 +/- 135 mg/min) vs. normal homozygotes (379 +/- 172 mg/min). Basal endogenous glucose production was not different (P = 0.20) between heterozygotes (175 +/- 27 mg/min) and normal homozygotes (164 +/- 14 mg/min). Endogenous glucose production during hyperinsulinemia was also not different (P = 0.22) between heterozygotes (77 +/- 57 mg/min) and normal homozygotes (56 +/- 16 mg/min). Total glucose disposal adjusted for residual endogenous glucose production was lower (P = 0.049) for heterozygotes (320 +/- 111 mg/min) than for normal homozygotes (441 +/- 183 mg/min). Our results suggest that obese postmenopausal women who are heterozygous for the Trp64Arg variant in the beta3AR gene have greater insulin resistance than age-, body composition-, and physical activity-matched women homozygous for the normal gene.     

The C825T polymorphism in the human G-protein beta3 subunit gene is not associated with diabetic nephropathy in Type I diabetes mellitus

In Type I (insulin-dependent) diabetes mellitus a genetic predisposition exists to nephropathy and is related to parental hypertension. Enhanced G-protein activation, a cellular phenotype observed in cultured cells from patients with essential hypertension, was recently documented in Type I diabetic subjects with nephropathy. This enhanced G-protein activation has been associated with a genetic variant in the G-protein beta3 subunit, GNB3. A C-->T polymorphism at position 825 in exon 10 is associated with G-protein activation, the T allele associated with enhanced activity. Furthermore the T allele was observed more frequently in a group with essential hypertension. In this report we have analysed the role of the C825T polymorphism in the predisposition to diabetic nephropathy in Type I diabetes. We have investigated the frequency of this polymorphism in a large case-control study and found no association of the T allele with diabetic nephropathy. Specifically carriage of the T allele as CT or TT was observed in 49% of 200 Type I diabetic control subjects with normoalbuminuria (diabetes duration 24 years) compared with 53% of 216 Type I diabetic subjects with nephropathy (overt proteinuria or end-stage renal failure). Within this group we have also examined the inheritance of C825T alleles in a family study and found no evidence for excess transmission of the T allele to Type I diabetic offspring with nephropathy (T allele transmitted to 51% of nephropathy offspring, C allele transmitted to 49% of nephropathy offspring, p = 0.79). In none of the Type I diabetic datasets examined was there any effect of genotype on variation in systolic or diastolic blood pressure. In conclusion we can find no evidence for the C825T polymorphism of the beta3 G-protein subunit as a major gene in the susceptibility to diabetic nephropathy in Type I diabetes.     

The Trp64Arg mutation of the beta3-adrenergic receptor is associated with hyperglycemia and current body mass index in Jamaican women

Helicobacter pylori is a major etiologic agent in gastroduodenal disorders. In this study, immunoglobulin A (IgA) antibodies to H. pylori antigens were evaluated in serum and gastric juice specimens obtained from patients with gastritis or peptic ulcers by utilizing antibody capture enzyme-linked immunosorbent assays (ACELISAs). Urease alpha subunit (UA), urease beta subunit (UB), the 66-kDa heat shock protein (HSP), and the 25-kDa protein (25K) were used as antigens for the ACELISAs. The antibody titers of the ACELISAs reflect the ratio of H. pylori-specific IgA to total IgA. The ratio is stable, although the antibody concentration fluctuates in gastric juice. By using ACELISAs it was possible to evaluate quantitatively not only serum IgA antibodies but also gastric juice secretory IgA (S-IgA) antibodies. In both serum IgA and gastric juice S-IgA ACELISAs, the titers of antibody to HSP and 25K were remarkably correlated with the histologic grade of gastritis, whereas those to UA and UB were not strongly correlated with histologic grade. Thus, it is useful for estimating the histologic grade of gastritis to quantify serum IgA and gastric juice S-IgA antibodies to HSP and 25K.     

Trp64Arg mutation of beta 3-adrenergic receptor and insulin sensitivity in subjects with glucose intolerance

We investigated the relationship between the Trp64Arg mutation in the beta 3-adrenergic receptor gene and insulin sensitivity, which was evaluated by the euglycemic-hyperinsulinemic-clamp technique, in 54 patients with impaired glucose tolerance (IGT) or non-insulin dependent diabetes mellitus (NIDDM) who were not receiving insulin therapy. The frequencies of Trp/Trp, Trp/Arg, and Arg/Arg genotypes in the patients were 63.0, 33.3, and 3.7%, respectively, which did not differ significantly from those of the 227 controls (67.0, 33.3, and 3.7%, respectively, which did not differ significantly from those of the 227 controls (67.0, 31.3, and 1.8%, respectively). The mean glucose infusion rate of the 34 patients with Trp/Trp did not differ from that of the 18 patients with Trp/Arg (4.3 +/- 2.2 and 5.3 +/- 2.4 mg/kg/min, respectively); while that of the 2 patients with Arg/Arg was 11.5 mg/kg/min. There were no differences in the BMI or fat distribution in the abdomen between each genotype of patients, although the frequency of the Arg64 allele tended to increase with body mass index (BMI) in the control subjects under 60 years of age, which suggests that the mutation is involved in weight gain.     

No effect of Trp64Arg beta3-adrenoceptor polymorphism on the plasma leptin concentration in Pima Indians

In rodents, administration of leptin promotes beta3-adrenergic stimulation of thermogenesis in brown adipose tissue. Conversely, administration of a beta3-adrenoceptor (beta3-AR) agonist decreases leptin mRNA expression and secretion, suggesting that leptin and sympathetic nervous system activity mediated through the beta3-AR comprise a negative-feedback loop. It has recently been proposed that a defect in the beta3-AR in humans may contribute to a resistance to the sympathetically mediated effects of leptin on thermogenesis and lipolysis, thus leading to obesity and type 2 diabetes mellitus. We thus hypothesized that the Trp64Arg variant in the human beta3-AR would be associated with elevated plasma leptin concentrations. We studied 101 healthy nondiabetic Pima Indians: 11 Arg64 homozygotes, 35 Trp64 homozygotes, and 55 heterozygotes. The fasting plasma leptin concentration as an absolute value or after adjustment for percent body fat and sex was not associated with the beta3-AR genotype. Thus, the data do not support an influence of the Trp64Arg variant on the plasma leptin concentration.     

Gender effect of the Trp64Arg mutation in the beta 3 adrenergic receptor gene on weight gain in morbid obesity

Phenotypic expression of the Trp64Arg mutation in the beta 3-adrenoceptor gene (beta 3-AR) has been found to be somewhat variable among different populations, suggesting that it may be influenced by genetic background and environmental factors. As sex may also influence gene allellic expression, we evaluated a potential gender effect of the Trp64Arg mutation in 292 morbidly obese subjects [body mass index (BMI) > or = m/kg2]. Although the 15 mutated obese females were younger than the non-mutated ones, the difference between their current weight and their weight at 20 years was significantly higher (62.4 +/- 20.0 kg versus 47.0 +/- 24.0 kg; p = 0.017). Moreover, in the mutated heterozygous female group, the mean Zscore (individual BMI minus reference French population mean BMI/SD of reference population BMI) was significantly higher (8.0 +/- 2.5 versus 6.0 +/- 2.0 SD of BMI, p = 0.0018), as was the maximal Zscore calculated from the maximal BMI that obese females reached during life (9.0 +/- 3.0 versus 7.0 +/- 2.5, p = 0.005). The regression curves of the Zscore against age showed that the curve of mutated females was shifted to the top, indicating that their BMI was higher regardless of age. These effects were not observed in the male group (the Zscore was 6.7 +/- 3.0 vs. 7.2, p = 0.7 respectively in mutated and non-mutated men). These data reinforce the hypothesis that the expression of the beta 3-AR susceptibility gene depends on additional factors including gender and possibly hormonal status.     

Meta-analysis of the association of Trp64Arg polymorphism of beta 3-adrenergic receptor gene with body mass index

A possible pathogenic polymorphism in the beta 3-adrenergic receptor gene (Trp64Arg) has been reported to be associated with increased body weight, clinical features of insulin resistance, and early development of type 2 diabetes mellitus in several populations. However, such findings have not been consistent among studies, making the hypothesis that this genetic marker is associated with clinical features controversial. To assess the effect of the genotypes on body mass index (BMI), we performed a meta-analysis of the data from the literature using an extension of ANOVA for continuous measures. In a total of 48 subgroups containing subjects with (n = 2447) and without (n = 6789) the Trp64Arg variant, the summary weighted mean difference in BMI was 0.30 (95% confidence interval, 0.13-0.47) kg/m2, indicating that variant carriers exhibited higher BMI (on the average, 0.30 kg/m2 higher) than normal homozygous subjects. In this case, there was no significant evidence against homogeneity of the effect (P = 0.36). This is the first meta-analysis assessing quantitative phenotypes in relation to a genetic polymorphism, and the results support the hypothesis that the Trp64Arg polymorphism is associated with BMI across diverse population groups, suggesting that the beta 3-adrenergic receptor gene locus plays a role in genetic predisposition to increased body weight in a universal manner.     

Meta-analysis of the association of the Trp64Arg polymorphism in the beta3 adrenergic receptor with body mass index

AIMS: To investigate the relationship in patients with heart failure between BP response to the first dose of ACE inhibitor and (1) plasma drug concentration and (2) baseline clinical and laboratory variables. METHODS: We studied individual placebo-corrected BP responses to initiation of treatment with one of a number ACE inhibitor preparations in 132 patients with mild to moderate CHF. Various pharmacokinetic/pharmacodynamic models were compared. We assessed the strength of association between baseline physiological and laboratory variables and the BP response as assessed directly from the AUC(0,10 h) and indirectly from the slope of the PK/PD relationship. Predictive models for response variables were developing using regression analysis. RESULTS: BP response was primarily related to plasma drug concentration. The association between the fall in BP and baseline variables was weak. The strongest single predictor of BP response was baseline mean arterial pressure (r2 = 5.8%, P = 0.02). The best combinations of predictor variables contained mean arterial pressure, plasma renin activity, creatinine concentration and age (r2 = 14.4%, P = 0.37). When the choice of ACE inhibitor was added, the predictive power of the model increased (r = 23.6%, P < 0.01) but left the majority of the variability in response unexplained. CONCLUSIONS: The first-dose blood pressure response to ACE inhibition cannot be accurately predicted from baseline pathophysiological variables in patients with mild to moderate CHF. The choice of ACE inhibitor accounts for a small proportion of the variability in response but wide inter-individual variability exists in the response to each treatment.     

Effects of Trp64Arg mutation in the beta 3-adrenergic receptor gene on body fat, plasma glucose level, lipid profile, insulin secretion and action in Chinese

A case of concurrent enchondroma and periosteal chondroma of the right proximal humerus in a 19-year-old woman is reported. Radiographs and CT scans showed a periosteal lesion with saucerization and spicula-like mineralization of the lateral aspect of the right proximal humerus and an ill-defined irregular lucency with stippled calcifications of the medullary cavity adjacent to it. MRI showed a long intramedullary lesion in addition to the surface lesion. There was no cortical disruption by imaging and gross examination. Histologically, both lesions showed benign cartilaginous tumors; concurrent enchondroma and periosteal chondroma of the humerus was therefore diagnosed. This combination in the same bone in a patient without enchondromatosis is exceedingly rare. Radiographic features may be confused with chondrosarcoma.     

Angiotensin-converting enzyme gene polymorphism in non-insulin dependent diabetes mellitus and its relationship with diabetic nephropathy

The effects of prolactin (PRL) on proliferation of cultured human uterine leiomyoma-derived smooth muscle cells (SMC) and its mechanism of action were investigated. PRL stimulated DNA synthesis and the expression of PRL receptor was identified by ribonuclease protection assay. Moreover, the regulation of mitogen-activated protein (MAP) kinase by PRL in leiomyoma-derived SMC was investigated. PRL stimulated MAP kinase activity, as detected by 32P incorporation into MAP-2, in a dose-dependent manner. PRL also rapidly stimulated MAP kinase phosphorylation as detected by in vivo phosphorylation using 32P labeling and phosphotyrosine immunoblotting. These results suggest that PRL stimulates the proliferation of human leiomyoma cells via the MAP kinase cascade.     

Autoantibodies associated with Type I diabetes mellitus persist after diagnosis in children

We have examined the effects of riluzole, a neuroprotective drug which stabilizes voltage-dependent sodium channels in their inactivated state and inhibits the release of glutamate in-vivo and in-vitro, on the release of newly taken up [3H]dopamine induced by ouabain, a potent and selective inhibitor of Na+/K+-ATPase in mouse striatal slices in-vitro. Riluzole potently (IC50 (concentration resulting in 50% inhibition) = 0.9+/-0.3 microM) and dose-dependently antagonized ouabain-stimulated [3H]dopamine release, the effect being observed at low concentrations. Tetrodotoxin (1 microM) and nomifensine (10 microM) also abolished ouabain-induced [3H]dopamine release. Blockade of glutamate receptors with dizocilpine (1 microM) and 6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-quinoxalinedione (YM-90K; 10 microM), alone or in combination, was without effect. Incubation of striatal slices with 50 microM La3+, which blocks voltage-dependent calcium channels, did not inhibit [3H]dopamine release induced by ouabain. The potent effects of riluzole observed in this model are probably related to its ability to block voltage-dependent sodium channels. The consequences of this activity are critically discussed in relation to the protective action of riluzole previously reported in various models of Parkinson's disease and other neurodegenerative disorders.     

Human atrial natriuretic peptide in patients with type 1 diabetes mellitus: is it related to the development of diabetic nephropathy?

There is controversy as to whether increased plasma levels of human atrial natriuretic peptide (hANP) in patients with type 1 diabetes mellitus may contribute to the development of diabetic nephropathy. Therefore, we decided to conduct two studies to examine the relationship of hANP levels to urinary albumin excretion and blood pressure. In a cross-sectional study, 83 randomly selected type 1 diabetic patients were investigated. 19 of the patients had increased urinary albumin excretion. 45 healthy volunteers served as controls. In a longitudinal study, 19 type 1 diabetic patients were examined for one year at monthly intervals. An increased risk of eventually developing diabetic nephropathy was identified in 7 out of these patients by repeatedly revealing increased urinary albumin excretion. On the average, hANP levels were increased in type 1 diabetic patients in comparison to controls (P < 0.001). In both studies, hANP levels were positively related (P < 0.05) to mean arterial blood pressure. There was no correlation between hANP levels and metabolic control. hANP levels lay within normal range irrespective of normal or elevated urinary albumin excretion provided that mean arterial blood pressure was normal. In the longitudinal study, increased urinary albumin and alpha-1-microglobulin excretion preceded the increase in both hANP levels and mean arterial blood pressure. Although hANP levels were evidently not related to the disease mechanisms of early diabetic nephropathy, it is tempting to speculate that hANP may contribute to the vicious circle connecting diabetic kidney disease to hypertension once that its levels are increased by elevated blood pressure.     

Correlates of hypoglycemic fear in Type I and Type II diabetes mellitus.

Surveyed 232 outpatients with Type I and Type II diabetes, all requiring insulin. For the Type I and Type II groups, higher scores on the Worry subscale of the Hypoglycemia Fear Survey (HFS-W) were associated with higher levels of trait anxiety and fear. Higher scores on the Behavior subscale were associated with higher levels of fear. Among Type I Ss only, HFS-W scores were also positively associated with past hypoglycemic experience and with difficulty in differentiating anxiety and hypoglycemic symptoms. These latter relations remained significant even after the variance resulting from trait anxiety and fear was removed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is PstI polymorphism of the angiotensin I converting enzyme gene associated with nephropathy development in non-insulin-dependent diabetes mellitus (preliminary study)

Nephropathy is a frequent complication of long term diabetes. Diabetic nephropathy is the major determinant of premature morbidity and mortality both in insulin-dependent (IDDM) and in non-insulin dependent-diabetes mellitus (NIDDM). There is good evidence that genetic predisposition plays a major role in development of diabetic nephropathy. This hypothesis is based on the observation that diabetic nephropathy clusters within families, both in IDDM and NIDDM. Components of the renin-angiotensin system (RAS) are plausible candidate genes to examine for a association with microalbuminuria and diabetic nephropathy. In this study we compared the distribution of PstI melting polymorphism at the ACE locus among NIDDM patients with diabetic nephropathy and in patients who, despite long duration of NIDDM, remain without this complication. The 220 NIDDM patients for whom DNA was available were classified into two groups according to their renal status: normoalbuminuric control subjects (n = 80) who are NIDDM patients with an A/C ratio < 2.5 and nephropathy cases (n = 140) who are NIDDM patients with A/C ratio > 2.5. Albumin excretion rate was assayed by radioimmunoassay. HbA1c was assayed using HPLC methods, creatinine--using Jaffe methods and DNA analysis using PCR reaction, and then after the amplification product was digested with PstI enzyme. The study revealed that PstI sequence differences ("+/= and -") in the ACE gene do not contribute to genetic susceptibility to diabetic nephropathy in NIDDM.     

Common amino acid substitutions in insulin receptor substrate-4 are not associated with Type II diabetes mellitus or insulin resistance

The family of insulin receptor substrates (IRS1-4) is defined by proteins with an overall similar structure. IRS-1 and IRS-2 have been shown to have key roles in cellular transmission of the action of insulin, insulin-like growth factor-1 and various cytokines. We have previously identified amino acid polymorphisms in the human IRS-1 and IRS-2 proteins. Given the documented importance of IRS-1 and -2 in insulin signalling and the implications of distribution of these genes for the pathogenesis of insulin resistance and diabetes, we decided that the most recently identified member of the IRS family, IRS-4, was a relevant candidate to examine for genetic variability which might be associated with subsets of diabetes or insulin resistance. The gene encoding IRS-4 was analysed by the single strand conformation polymorphism technique in 83 Danish Caucasians with Type II (non-insulin-dependent) diabetes mellitus. Five amino acid polymorphisms were identified: Leu34Phe, Arg411Gly, Gly584Cys, His879Asp and Lys883Thr. In an association study of 324 patients with Type II diabetes and 267 control subjects with normal glucose tolerance the polymorphism at codon 34 was found with allelic frequencies of 3.9 and 2.3 %, respectively, the variant at codon 411 with allelic frequencies of 3.9 and 5.6%, respectively, and the variant at codon 879 with frequencies of 19.2 and 18.0%, respectively. Each carrier of the codon 34 polymorphism was also a carrier of the codon 411 and codon 879 variants and similarly, carriers of the variant at codon 411 were also carriers of the polymorphism at codon 879. The variants at codon 584 and 883 were each found in only one Type II diabetic patient. The allelic frequencies of the variants at codon 411 and 879 were also determined in 380 young healthy subjects (4.6 and 18.1 %, respectively). The insulin sensitivity index as estimated by Bergman's minimal model of the young healthy subjects carrying either polymorphism was indistinguishable from the carriers of wild-type IRS-4. Moreover, none of the men were heterozygous for the IRS-4 polymorphisms indicating that the gene is located on the X-chromosome. In conclusion, amino acid polymorphisms in human IRS-4 are common in Caucasians but are not associated with Type II diabetes or with insulin resistance in young healthy subjects.     

Treatment of hypertension associated with diabetes mellitus

The number of patients with non-insulin-dependent-diabetes mellitus (NIDDM) is dramatically increasing in Japan and estimated to be 6 million, more than one of ten adults. It is well known that more than a half of diabetics are hypertensive. Therefore, it is very important to treat hypertension to reduce cardiovascular events as well as end-stage renal disease. At first, life style modification such as body weight reduction, exercise and restriction of salt and alcohol intake will be recommended. Improved glycemic control by such a non-pharmacological therapy will lower blood pressure. Recent studies demonstrated that hypoglycemic agents improving insulin resistance such as metformin and troglitazone reduce blood pressure. If these maneuvers do not lower blood pressure, hypotensive medication will be necessary. As a first line therapy, ACE inhibitor, alpha 1-blocker or Ca-channel blocker will be selected. In diabetics with proteinuria or micro-albuminuria, ACE inhibitors will be effective to delay the progression of diabetic nephropathy.     

Plasma homocysteine is related to albumin excretion rate in patients with diabetes mellitus: a new link between diabetic nephropathy and cardiovascular disease?

The high risk of cardiovascular disease in patients with diabetes mellitus, particularly in those with nephropathy, is not completely explained by classical risk factors. A high plasma homocysteine concentration is an independent risk factor for cardiovascular disease but information on its association with diabetes is limited. Fasting homocysteine concentrations were measured in the plasma of 165 diabetic patients (75 with insulin-dependent [IDDM]; 90 with non-insulin-dependent diabetes [NIDDM]) and 56 non-diabetic control subjects. Other measurements included the prevalence of diabetic complications, glycaemic control, lipid and lipoprotein levels, vitamin status and renal function tests. Patients with NIDDM had higher homocysteine levels than control subjects, whereas IDDM patients did not (9.2 +/- 4.5 vs 7.7 +/- 2 micromol/l, p < 0.01; and 7.0 +/- 3 vs 7.4 +/- 2 micromol/l, NS). Univariate correlations and multiple regression analysis showed albumin excretion rate to be the parameter with the strongest independent association with homocysteine. Patients with both types of diabetes and nephropathy had higher plasma homocysteine concentrations than those without nephropathy. Increases of homocysteine in plasma were related to increases in the severity of the nephropathy. Fasting hyperhomocysteinaemia was considered as the mean of the plasma homocysteine for all control subjects (7.5 +/- 2.1 micromol/l) + 2 SD (cut-off = 11.7 micromol/l). Nephropathy was present in 80 % of diabetic patients with fasting hyperhomocysteinaemia. In conclusion, increases in fasting homocysteine in diabetic patients are associated with increased albumin excretion rate, especially in those with NIDDM, thus providing a potential new link between microalbuminuria, diabetic nephropathy and cardiovascular disease.