Search

Recently, the genetic cause of several syndromic forms of glycemia dysregulation has been described. One of them, MEHMO syndrome, is a rare X-linked syndrome recently linked to the EIF2S3 gene mutations. MEHMO is characterized by Mental retardation, Epilepsy, Hypogonadism/hypogenitalism, Microcephaly, and Obesity. Moreover, patients with MEHMO had also diabetes and endocrine phenotype, but detailed information is missing. We aimed to provide more details on the endocrine phenotype in two previously reported male probands with MEHMO carrying a frame-shift mutation (I465fs) in the EIF2S3 gene. Both probands had a neonatal hypoglycemia, early onset insulin-dependent diabetes, and hypopituitarism due to dysregulation and gradual decline of peptide hormone secretion. Based on the clinical course in our two probands and also in previously published patients, neonatal hypoglycemia followed by early-onset diabetes and hypopituitarism may be a consistent part of the MEHMO phenotype.

Background: Inactivating mutations of the hypothalamic transcription factor singleminded1 (SIM1) have been shown as a cause of early-onset severe obesity. However, to date, the contribution of SIM1 mutations to the obesity phenotype has only been studied in a few populations. In this study, we screened the functional regions of SIM1 in severely obese children of Slovak and Moravian descent to determine if genetic variants within SIM1 may influence the development of obesity in these populations., Methods: The SIM1 promoter region, exons and exon-intron boundaries were sequenced in 126 unrelated obese children and adolescents (2-18 years of age) and 41 adult lean controls of Slovak and Moravian origin. Inclusion criteria for the children and adolescents were a body mass index standard deviation score higher than 2 SD for an appropriate age and sex, and obesity onset at less than 5 years of age. The clinical phenotypes of the SIM1 variant carriers were compared with clinical phenotypes of 4 MC4R variant carriers and with 27 unrelated SIM1 and MC4R mutation negative obese controls that were matched for age and gender., Results: Seven previously described SIM1 variants and one novel heterozygous variant p.D134N were identified. The novel variant was predicted to be pathogenic by 7 in silico software analyses and is located at a highly conserved position of the SIM1 protein. The p.D134N variant was found in an 18 year old female proband (BMI 44.2kg/m2; +7.5 SD), and in 3 obese family members. Regardless of early onset severe obesity, the proband and her brother (age 16 years) did not fulfill the criteria of metabolic syndrome. Moreover, the variant carriers had significantly lower preferences for high sugar (p = 0.02) and low fat, low carbohydrate, high protein (p = 0.02) foods compared to the obese controls., Conclusions: We have identified a novel SIM1 variant, p.D134N, in 4 obese individuals from a single pedigree which is also associated with lower preference for certain foods.

Objective: Hypertrophic obesity is associated with impaired insulin sensitivity and lipid-mobilizing activity of zinc-α2-glycoprotein. Adipose tissue (AT) of growth hormone (GH) -deficient patients is characterized by extreme adipocyte hypertrophy due to defects in AT lipid metabolism. It was hypothesized that zinc-α2-glycoprotein is regulated by GH and mediates some of its beneficial effects in AT., Methods: AT from patients with GH deficiency and individuals with obesity-related GH deficit was obtained before and after 5-year and 24-month GH supplementation therapy. GH action was tested in primary human adipocytes. Relationships of GH and zinc-α2-glycoprotein with adipocyte size and insulin sensitivity were evaluated in nondiabetic patients with noncancerous cachexia and hypertrophic obesity., Results: AT in GH-deficient adults displayed a substantial reduction of zinc-α2-glycoprotein. GH therapy normalized AT zinc-α2-glycoprotein. Obesity-related relative GH deficit was associated with almost 80% reduction of zinc-α2-glycoprotein mRNA in AT. GH increased zinc-α2-glycoprotein mRNA in both AT of obese men and primary human adipocytes. Interdependence of GH and zinc-α2-glycoprotein in regulating AT morphology and metabolic phenotype was evident from their relationship with adipocyte size and AT-specific and whole-body insulin sensitivity., Conclusions: The results demonstrate that GH is involved in regulation of AT zinc-α2-glycoprotein; however, the molecular mechanism linking GH and zinc-α2-glycoprotein in AT is yet unknown., (© 2014 The Obesity Society.)

Objective: To examine the regulatory aspects of zinc-α2-glycoprotein (ZAG) association with obesity-related insulin resistance., Methods: ZAG mRNA and protein were analyzed in subcutaneous adipose tissue (AT) and circulation of lean, obese, prediabetic, and type 2 diabetic men; both subcutaneous and visceral AT were explored in lean and extremely obese. Clinical and ex vivo findings were corroborated by results of in vitro ZAG silencing experiment., Results: Subcutaneous AT ZAG was reduced in obesity, with a trend to further decrease with prediabetes and type 2 diabetes. ZAG was 3.3-fold higher in subcutaneous than in visceral AT of lean individuals. All differences were lost in extreme obesity. Obesity-associated changes in AT were not paralleled by alterations of circulating ZAG. Subcutaneous AT ZAG correlated with adiposity, adipocyte hypertrophy, whole-body and AT insulin sensitivity, mitochondrial content, expression of GLUT4, PGC1α, and adiponectin. Subcutaneous AT ZAG and adipocyte size were the only predictors of insulin sensitivity, independent on age and BMI. Silencing ZAG resulted in reduced adiponectin, IRS1, GLUT4, and PGC1α gene expression in primary human adipocytes., Conclusions: ZAG in subcutaneous, but not in visceral AT, was markedly reduced in obesity. Clinical, cellular, and molecular evidence indicate that ZAG plays an important role in modulating whole-body and AT insulin sensitivity., (Copyright © 2014 The Obesity Society.)

Irisin was identified as a myokine secreted by contracting skeletal muscle, possibly mediating some exercise health benefits via 'browning' of white adipose tissue. However, a controversy exists concerning irisin origin, regulation and function in humans. Thus, we have explored Fndc5 gene and irisin protein in two clinical studies: (i) a cross-sectional study (effects of type 2 diabetes (T2D) in drug-naive men) and (ii) an intervention study (exercise effects in sedentary, overweight/obese individuals). Glucose tolerance and insulin sensitivity were assessed. Maximal aerobic capacity and muscle strength were measured before and after training. Body composition (magnetic resonance imaging), muscle and liver fat content (1H-magnetic resonance spectroscopy (MRS)) and in vivo muscle metabolism (32P-MRS) were determined. Skeletal muscle and subcutaneous abdominal adipose tissue samples were taken in the fasted state and during euglycaemic hyperinsulinaemia (adipose tissue) and before/after exercise training (muscle). We found that muscle Fndc5 mRNA was increased in prediabetes but not T2D. Fndc5 in adipose tissue and irisin in plasma were reduced in T2D by 40% and 50%, respectively. In contrast, T2D-derived myotubes expressed/secreted the highest levels of Fndc5/irisin. Neither hyperinsulinaemia (adipose tissue/plasma) nor exercise (muscle/plasma) affected Fndc5/irisin in vivo. Circulating irisin was positively associated with muscle mass, strength and metabolism and negatively with fasting glycaemia. Glucose and palmitate decreased Fndc5 mRNA in myotubes in vitro. We conclude that distinct patterns of Fndc5/irisin in muscle, adipose tissue and circulation, and concordant in vivo down-regulation in T2D, indicate that irisin might distinguish metabolic health and disease. Moreover, Fndc5/irisin was discordantly regulated in diabetic muscle and myotubes in vitro, suggesting that whole body factors, such as glucose and fatty acids, might be important for irisin regulation. Exercise did not affect Fndc5/irisin. However, irisin was positively linked to muscle mass, strength and metabolism, pointing to common regulatory factors and/or the potential for irisin to modify muscle phenotype.

Objective: This study was aimed to evaluate possible obesogenic and diabetogenic impact of highly increased serum level of persistent organochlorinated pollutants POPs, such as polychlorinated biphenyls (PCBs), dichlorodiethyl-dichloroethylene (p,p'-DDE), and hexachlorobenzene (HCB), on the level of obesity markers (cholesterol and triglyceride level in serum, and body mass index [BMI]) and diabetes markers (fasting glucose and fasting insulin in serum) in inhabitants of Eastern Slovakia., Methods: In young (21-40 years) males (n=248) and females (n=330) as well as in old (41-75 years) males (n=586) and females (n=889), the serum levels of 15 polychlorinated biphenyl congeners (Σ15PCBs), p,p'-DDE and HCB, and serum insulin, testosterone, total cholesterol, triglycerides and glucose levels have been estimated by high resolution gas chromatography/mass spectrometry and by the appropriate electrochemiluminiscent immunoassay or chemical methods, respectively., Results: In both age groups of males and females, the levels of Σ15PCBs, p,p'-DDE, and HCB were very high and their mutual interrelations were highly significant (p<0.01). However, it should be noted that no significant changes were found in individual variables related to very high level of Σ15PCBs, except of increased BMI (p>0.05) in females.In all ages and gender groups, defined above general as related to increasing level of individual OCPs in individual age and gender groups, significant increase in cholesterol and triglyceride levels as well as BMI values, supported their obesogenic effect, while significant increase in fasting glucose and insulin in serum, supported their diabetogenic effect. Finally, highly significant decrease in testosterone level, as found in both young and old males, supported the antiandrogenic effect, namely of HCB. However, somewhat less of p,p'-DDE, while PCBs did not show any such effect in spite of their very high level., Conclusions: Highly increased blood levels of diabetes (fasting glucose and insulin) and obesity markers (cholesterol, triglyceride and BMI) were found in large groups of males and females in highly polluted area of Slovakia. Significant decrease in testosterone level was also observed in males.

High prevalence of obesity in all of age categories is currently one of the biggest problem in medicine. Identification of etiology of obesity can individualise an approach to the patient and it is essential for choosing a target management and therapy. Beside the largest group with polygenic inheritance are clinically important also patients with "syndromic obesity", where obesity is only one of the signs and monogenic obesity, where obesity is the major clinical phenotype (patients with mutations in gene for leptin, leptine receptor, prohormone convertase 1, melanocortine receptor 4, brain-derived neurotropic factor and tyrosin kinase receptor B). The monogenic obesity includes 3-4% of all patients with obesity. This review article brings newest insight on genetics, clinical manifestation, diagnostics and therapy of these diseases.

Objective: Many adipokines, inflammatory cytokines, and other proteins produced by adipose tissue have been shown to be involved in the development of obesity-related insulin resistance. Nevertheless, new factors that play an important role in these processes are still emerging. Therefore, we screened the level of 120 different proteins in biopsies of subcutaneous adipose tissue (ScAT) of lean and obese subjects., Research Methods and Procedures: All studied volunteers (12 obese with BMI >30 and 6 lean with BMI <25 kg/m(2)) were young, clinically healthy, and drug-naive males with normal glucose tolerance. The ScAT was obtained by a needle biopsy from the umbilical region. Protein levels were assessed in adipose tissue lysates using protein arrays; mRNA levels were determined with the aid of real-time reverse transcription-polymerase chain reaction (RT-PCR)., Results: The obese subjects had higher fasting plasma glucose (although within the normal range) and insulin levels, increased high sensitivity C-reactive protein (hsCRP) in circulation, and decreased in vivo insulin action. Using the protein array technique, it was shown that of 120 proteins measured, 27 showed higher levels (leptin, HGF, EGF-R, FGF-6, IGF-1sR, Fas/Apo-1, ENA-78, PARC, lymphotactin, HCC-4, IL-10, IL-1a, IL-1R1, IL-1R4, IL-12p70, angiopoietin-2, Axl, Dtk, MIF, MIP-1a, -1b, -3b, MSP-a, osteoprotegerin, TECK, TIMP-1, -2) and only one (RANTES) showed a lower level in ScAT of obese subjects when compared with the lean controls (p < 0.05). The real-time RT-PCR confirmed the results of protein arrays for leptin, MIF, MIP-1a, TIMP-2, adiponectin, IL-6, and TNF-alpha but not for RANTES., Discussion: To our knowledge, this is the first protein array data on a very early dysregulation of ScAT protein levels in insulin-resistant obese, but apparently healthy, subjects with normal glucose tolerance.

Tetradecylthioacetic acid (TTA) is a non-beta-oxidizable fatty acid analog, which potently regulates lipid homeostasis. Here we evaluate the ability of TTA to prevent diet-induced and genetically determined adiposity and insulin resistance. In Wistar rats fed a high fat diet, TTA administration completely prevented diet-induced insulin resistance and adiposity. In genetically obese Zucker (fa/fa) rats TTA treatment reduced the epididymal adipose tissue mass and improved insulin sensitivity. All three rodent peroxisome proliferator-activated receptor (PPAR) subtypes were activated by TTA in the ranking order PPARalpha > PPARdelta > PPARgamma. Expression of PPARgamma target genes in adipose tissue was unaffected by TTA treatment, whereas the hepatic expression of PPARalpha-responsive genes encoding enzymes involved in fatty acid uptake, transport, and oxidation was induced. This was accompanied by increased hepatic mitochondrial beta-oxidation and a decreased fatty acid/ketone body ratio in plasma. These findings indicate that PPARalpha-dependent mechanisms play a pivotal role, but additionally, the involvement of PPARalpha-independent pathways is conceivable. Taken together, our results suggest that a TTA-induced increase in hepatic fatty acid oxidation and ketogenesis drains fatty acids from blood and extrahepatic tissues and that this contributes significantly to the beneficial effects of TTA on fat mass accumulation and peripheral insulin sensitivity.

Na+, K+ -ATPase activity was measured in red blood cells from 20 nondiabetic euthyroid male Pima Indians with varying degrees of obesity; their body mass indices ranged from 22-60 kg/m2. The na+, K+ -ATPase, measured both by 86Rb uptake in intact cells and ATP hydrolysis by purified membranes, was inversely correlated with body mass index (r = -0.62; P less than 0.005 and r = -0.75; P less than 0.0001, respectively). These results confirm that obesity is associated with decreased Na+, K+ -ATPase in intact red blood cells, and provide the first demonstration of a reduced sodium pump in isolated red cell membrane preparations from obese men.

To compare the ability of insulin to regulate lipolysis in lean and obese subjects, free fatty acid (FFA) suppression was compared in groups of six lean [body mass index, 25.7 +/- 1.1 (+/-SEM) kg/m2] and six obese (body mass index, 48.8 +/- 3.1) Pima Indians during euglycemic hyperinsulinemic clamps which increased plasma insulin levels approximately 10, 20, and 100 microU/ml above basal concentrations. Basal FFA concentrations were slightly, but not significantly, elevated in the obese group (445 +/- 35 vs. 406 +/- 40 mu eg/liter). The mean decline in FFA from basal after 60-90 min of insulin infusion in the obese group was somewhat less than that in the lean group at the lower doses [67 +/- 23 vs. 132 +/- 32 (P = NS) during the 10-microU clamp, and 144 +/- 39 vs. 217 +/- 20 (P = NS) during the 20-microU clamp] and was almost identical in the two groups during the 100-microU clamp (226 +/- 29 vs. 229 +/- 51). In contrast, insulin-mediated glucose disposal at all insulin increments was much lower in the obese group (0.33 +/- 0.03, 0.56 +/- 0.04, and 1.39 +/- 0.04 mg/kg X min) than in the lean group (0.78 +/- 0.06, 1.67 +/- 0.12, and 4.96 +/- 0.26; P less than 0.001). The data suggest that although the obese subjects exhibited significant resistance to the glucoregulatory action of insulin, there were only small changes in insulin's antilipolytic effects. Relative maintenance of sensitivity to the antilipolytic action of insulin in the presence of resistance to insulin's glucoregulatory action could maintain fat deposition in obese individuals.

Na, K-ATPase activity may have a significant role in cellular thermogenesis. Reduced thermogenesis and an increased accumulation of unused calories in the form of fat could result from reduced basal or insulin-stimulated Na,K-ATPase activity in obese insulin-resistant man. We have previously demonstrated reduced Na,K-ATPase activity in intact red cells and their isolated membranes from obese humans. To determine if the reduced enzyme activity in obese subjects is the result of inherent cellular defects in the regulation of Na,K-pump activity, basal and insulin-stimulated rates of ouabain-inhibitable Rb uptake were measured in diploid fibroblasts from subjects with a range of body mass indices (BMI). Cell cultures were established from five extremely obese subjects (BMI greater than 40 kg/m2) with fasting hyperinsulinemia (38 +/- 6 microU/mL) and in four control (BMI less than 30 kg/m2) normoinsulinemic (14 +/- 3 microU/mL) subjects. Basal (17 +/- 3 v 23 +/- 2 nmol/L/min/10(10) cells +/- SEM) and maximal insulin-stimulated Na,K-pump activities (26 +/- 3 v 32 +/- 3 nmol/L/min/10(10) cells) were similar in the obese and control subjects. Maximal insulin stimulation for both groups was observed in four to eight minutes, and one-half maximal response required 2.5 ng/ml insulin. Cell density was negatively correlated with basal (r = 0.75, p less than 0.001) and maximally stimulated Na,K-pump activity (r = -0.73, p less than 0.001). Adjustment for this relationship did not influence the conclusions. Comparison of the results from the obese and control groups indicates (a) no evidence for an intrinsic cellular difference in basal Na,K-pump activity related to obesity and (b) no difference in insulin regulation of Na,K-pump activity, in fibroblasts from obese subjects.

The ability of varying levels of circulating insulin to suppress alpha- and beta-cell secretion was assessed by plasma glucagon and C-peptide measurement in 6 obese and 6 nonobese subjects maintained in a euglycemic state, with an insulin concentration elevated by 10, 20, or 100 microU/ml above basal levels by a primed-continuous infusion of insulin. The 10-microU/ml increase did not suppress C-peptide levels significantly in either group. However, incremental increases in plasma insulin of approximately 20 and 100 microU/ml above basal suppressed plasma C-peptide by 0.27 +/- 0.14 and 0.53 +/- 0.07 pmol/ml, respectively, in the obese subjects (14% and 31% of the basal values of 2.20 +/- 0.18 and 2.19 +/- 0.26 pmol/ml, respectively) and by 0.16 +/- 0.06 and 0.17 +/- 0.06 pmol/ml in the nonobese subjects (20% and 25% the basal values of 0.74 +/- 0.11 and 0.78 +/- 0.11 pmol/ml, respectively). Plasma glucagon levels were suppressed to a similar degree in each group in a dose-related manner during both the 20-microU/ml and 100-microU/ml clamps. We were unable to identify an increment of insulin that suppressed C-peptide and/or glucagon in one group but not in another. These data demonstrate inhibition of alpha- and beta-cell secretion by insulin within its physiologic range in both non-obese and obese man, and exclude insulin resistance of alpha- and beta-cells in obese individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of rigorous insulin treatment on insulin action (insulin clamp) and secretion (plasma insulin response to glucose) were studied in 13 obese patients with non-insulin-dependent diabetes mellitus (NIDDM). Improvements were documented in fasting (P less than 0.0001) and postprandial (P less than 0.0001) plasma glucose concentrations, insulin secretion after oral glucose (P less than 0.001), and insulin action (P less than 0.005) after 30 days of therapy. Mean integrated plasma insulin response to glucose increased 2.5-fold after insulin therapy, but this improvement varied considerably from patient to patient. Insulin action also increased with insulin treatment and the resulting values were no longer significantly different from a weight- and age-matched group of subjects with normal glucose tolerance. However, there was considerable patient-to-patient variation in the degree to which insulin action was enhanced. The insulin-induced improvements in glucose tolerance persisted for at least 2 wk after insulin withdrawal, and were associated with continued increased insulin secretion and insulin action. In conclusion, control of hyperglycemia for 1 mo led to improvements in both insulin secretion and action in a series of obese patients with NIDDM that persisted for at least 2 wk after cessation of therapy.

Insulin secretion and insulin resistance were examined in seven obese type II diabetics before and after control of plasma glucose levels without weight loss. Control was achieved by regular insulin injection (60-205 U/day in four doses). After 10 days of therapy, plasma insulin and C-peptide responses to oral glucose were significantly improved. Insulin-induced glucose rates, estimated by the glucose clamp technique, averaged 1.08 +/- 0.30 mg/kg. min (mean +/- SEM; n = 7) before treatment and were unchanged (1.08 +/- 0.25) after treatment. These indicate that short term control of plasma glucose improved insulin secretion but not insulin sensitivity. The impaired insulin secretion and insulin sensitivity in type II diabetics appears to be, in part, secondary to metabolic abnormalities associated with hyperglycemia.

Six obese patients with recent-onset, non-insulin-dependent diabetes underwent assessment of glucose tolerance, insulin secretory capacity, and insulin-induced glucose disposal before and after 6-10 wk of intensive aerobic training while maintaining body weight. Fasting plasma glucose declined in every subject (average = -33 mg/dl), and oral glucose tolerance (3 h integrated plasma glucose) improved in five of the six (average = -74 mg X 3 h/dl) after training. Individual improvement in control of plasma glucose was directly proportional to degree of hyperglycemia before training and correlated well with an observed improvement in the early (30-min) plasma insulin response to oral glucose (all six subjects). The response of insulin action to training was highly variable; although the observed increase in average insulin-induced glucose disposal rate (M) during the euglycemic clamp did not reach statistical significance in our small cohort, the relative change in M was directly related to reduction in fasting insulin levels after training. Our results show that regular endurance exercise is effective in improving glucose homeostasis and may serve as an adjunct to other modes of treatment in recent-onset, non-insulin-dependent diabetic individuals.