Determinants of testosterone levels in human male obesity.

Testosterone (T) levels are decreased in obese men, but the underlying causes are incompletely understood. Our objective was to explore the relation between low (free) T levels and male obesity, by evaluating metabolic parameters, subcutaneous adipose tissue (SAT) aromatase expression, and parameters of the hypothalamic-pituitary-gonadal axis. We recruited 57 morbidly obese men [33 had type 2 diabetes (DM2)] and 25 normal-weight men undergoing abdominal surgery. Fourteen obese men also attended a follow-up, 2 years after gastric bypass surgery (GBS). Circulating T levels were quantified by LC-MS/MS, whereas free T levels were measured using serum equilibrium dialysis and sex hormone-binding globulin, luteinizing hormone, and follicle-stimulating hormone by immunoassay. SAT biopsies were used to determine adipocyte cell size and aromatase expression by real-time PCR. Total and free T levels were decreased in obese males versus controls, with a further decrease in obese men with DM2 versus obese men without DM2. There were no differences in aromatase expression among the study groups, and sex steroids did not correlate with aromatase expression. Pearson analysis revealed an inverse association between (free) T and SAT cell size, triglycerides, and HOMA-IR. Multivariate analysis confirmed the inverse association between (free) T and SAT cell size (ß = -0.321, P = 0.037 and ß = -0.441, P = 0.011, respectively), independent of age, triglycerides, HOMA-IR, obesity, or diabetes. T levels were normalized 2 years after GBS. These data suggest that SAT cell size rather than SAT aromatase expression or parameters of the hypothalamic-pituitary-gonadal axis is related to low T in male obesity, which points to adipose cell size-related metabolic changes as a major trigger in decreased T levels.

Moxifloxacin dosing in post-bariatric surgery patients.

INTRODUCTION: Given the ever increasing number of obese patients and obesity related bypass surgery, dosing recommendations in the post-bypass population are needed. Using a population pharmacokinetic (PK) analysis and PK-pharmacodynamic (PD) simulations, we investigated whether adequate moxifloxacin concentrations are achieved in this population. METHODS: In this modelling and simulation study we used data from a trial on moxifloxacin PK. In this trial, volunteers who had previously undergone bariatric surgery (at least 6 months prior to inclusion), received two doses (intravenous and oral) of 400 mg moxifloxacin administered on two occasions. RESULTS: In contrast to other papers, we found that moxifloxacin PK were best described by a three compartmental model using lean body mass (LBM) as a predictor for moxifloxacin clearance. Furthermore, we showed that the probability of target attainment for bacterial eradication against a hypothetical Streptococcus pneumoniae infection is compromised in patients with higher LBM, especially when targeting microorganisms with minimum inhibitory concentrations (MICs) of 0.5 mg l(-1) or higher (probability of target attainment (PTA) approaching zero). When considering the targets for suppression of bacterial resistance formation, even at MIC values as low as 0.25 mg l(-1) , standard moxifloxacin dosing does not attain adequate levels in this population. Furthermore, for patients with a LBM of 78 kg or higher, the probability of hitting this target approaches zero. CONCLUSIONS: Throughout our PK-PD simulation study, it became apparent that, whenever optimal bacterial resistance suppression is deemed necessary, the standard moxifloxacin dosing will not be sufficient. Furthermore, our study emphasizes the need for a LBM based individualized dosing of moxifloxacin in this patient population.

Activin A is associated with impaired myocardial glucose metabolism and left ventricular remodeling in patients with uncomplicated type 2 diabetes.

BACKGROUND: Activin A released from epicardial adipose tissue has been linked to contractile dysfunction and insulin resistance in cardiomyocytes. This study investigated the role of activin A in clinical diabetic cardiomyopathy by assessing whether circulating activin A levels associate with cardiometabolic parameters in men with uncomplicated type 2 diabetes (T2D), and the effects of treatment with pioglitazone versus metformin on these associations. METHODS: Seventy-eight men with uncomplicated T2D and fourteen healthy men with comparable age were included, in this randomized, double-blind, active comparator intervention study. All T2D men were on glimipiride monotherapy, and randomized to a 24-week intervention with either pioglitazone or metformin. Cardiac dimensions and -function were measured using magnetic resonance imaging, whilst myocardial glucose metabolism (MMRglu) was determined using [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography during a hyperinsulinemic-euglycemic clamp. RESULTS: Circulating activin A levels were comparable in T2D men and controls. Activin A levels were independently inversely associated with MMRglu, and positively with left ventricular mass/volume (LVMV)-ratio in T2D men. Intervention with metformin decreased activin A levels, whereas pioglitazone did not alter activin A levels. The changes in plasma activin A levels were not correlated with the changes in MMRglu following either pioglitazone or metformin treatment. A borderline significant correlation (p = 0.051) of changes in plasma activin A levels and changes in LVMV-ratio was observed after pioglitazone treatment. CONCLUSIONS: Circulating activin A levels are associated with impaired myocardial glucose metabolism and high LVMV-ratio in patients with uncomplicated T2D, reflecting a potential detrimental role in early human diabetic cardiomyopathy. TRIAL REGISTRATION NUMBER: Current Controlled Trials SRCTN53177482.

Activin A impairs insulin action in cardiomyocytes via up-regulation of miR-143.

AIMS: Enhanced activin A release from epicardial adipose tissue (EAT) has been linked to the development of cardiac dysfunction in type 2 diabetes (T2D). This study examined whether the inhibition of insulin action induced by epicardial adipokines in cardiomyocytes can be ascribed to alterations in miRNA expression. METHODS AND RESULTS: Expression levels of miRNAs were assessed by real-time PCR in primary adult rat cardiomyocytes (ARC) exposed to conditioned media generated from EAT biopsies (CM-EAT) from patients with and without T2D. CM-EAT-T2D altered the expression of eight miRNAs in ARC vs. CM-EAT from patients without T2D. Of these, only expression of the miR-143/145 cluster was affected by activin A in the same direction as CM-EAT-T2D. Accordingly, activin A neutralizing antibodies prevented the induction of the miR-143/145 cluster by CM-EAT-T2D. Subsequently, the impact of the miR-143/145 cluster on insulin action was investigated. Transfection of HL-1 cells with precursor-miR-143 (pre-miR-143), but not pre-miR-145, blunted the insulin-mediated phosphorylation of Akt and its substrate proline-rich Akt substrate of 40 kDa (PRAS40), and reduced insulin-stimulated glucose uptake. Also lentivirus-mediated expression of pre-miR-143 in ARC reduced insulin-induced Akt phosphorylation. These effects were ascribed to down-regulation of the miR-143 target and regulator of insulin action, the oxysterol-binding protein-related protein 8 (ORP8) in both ARC and HL-1 cells. Finally, LNA-anti-miR-143 protected against the detrimental effects of CM-EAT-T2D on insulin action in ARC. CONCLUSION: Activin A released from EAT-T2D inhibits insulin action via the induction of miR-143 in cardiomyocytes. This miRNA inhibits the Akt pathway through down-regulation of the novel regulator of insulin action, ORP8.

Secretory products from epicardial adipose tissue of patients with type 2 diabetes mellitus induce cardiomyocyte dysfunction.

BACKGROUND: Secreted factors from epicardial adipose tissue (EAT) have been implicated in the development of cardiomyocyte dysfunction. This study aimed to assess whether alterations in the secretory profile of EAT in patients with type 2 diabetes mellitus (DM2) affect contractile function and insulin action in cardiomyocytes. METHODS AND RESULTS: Contractile function and insulin action were analyzed in primary adult rat cardiomyocytes incubated with conditioned media (CM) generated from explants of EAT biopsies obtained from patients without and with DM2. CM from subcutaneous and pericardial adipose tissue biopsies from the same patients served as the control. Cardiomyocytes treated with CM (EAT) from DM2 patients showed reductions in sarcomere shortening, cytosolic Ca(2+) fluxes, expression of sarcoplasmic endoplasmic reticulum ATPase 2a, and decreased insulin-mediated Akt-Ser473-phosphorylation as compared with CM from the other groups. Profiling of the CM showed that activin A, angiopoietin-2, and CD14 selectively accumulated in CM-EAT-DM2 versus CM-EAT in patients without DM2 and CM from the other fat depots. Accordingly, EAT biopsies from DM2 patients were characterized by clusters of CD14-positive monocytes. Furthermore, SMAD2-phosphorylation, a downstream target of activin A signaling, was elevated in cardiomyocytes treated with CM (EAT) from DM2 patients, and the detrimental effects of CM (EAT) from DM2 patients were partially abolished in cardiomyocytes pretreated with a neutralizing antibody against activin A. Finally, both recombinant activin A and angiopoietin-2 reduced cardiomyocyte contractile function, but only activin A reduced the expression of sarcoplasmic endoplasmic reticulum ATPase 2a. CONCLUSIONS: Collectively, our data implicate DM2-related alterations in the secretory profile of EAT in the pathogenesis of diabetes mellitus-related heart disease.

Endogenous oestradiol and cardiovascular disease in healthy men: a systematic review and meta-analysis of prospective studies.

CONTEXT: The literature provides no clear answer as to whether total oestradiol (E2) concentrations increase the risk of incident cardiovascular disease (CVD) in healthy men. OBJECTIVE: The authors conducted a systematic review and meta-analysis to estimate the predictive value of E2 for CVD, and to identify study features explaining conflicting results. DATA SOURCES: Articles were identified by a Medline and Embase search and citation tracking. STUDY SELECTION: Eligible articles were prospective population-based cohorts and nested case-control studies on E2 and incident cardiovascular disease (CVD), including myocardial infarction, stroke or death from coronary heart disease. DATA-EXTRACTION: Independent researchers re-expressed associations of E2 and incident CVD in a uniform manner to be used in meta-regression analyses for identification of study features explaining conflicting results, and to estimate the predictive value of E2 for CVD. RESULTS AND CONCLUSIONS: 14 studies out of 128 electronically identified articles were eligible. Data to be used for meta-analysis could be calculated in seven cases, and in the remaining seven cases, data of three more became available by contacting those authors. Overall, a non-significant association was found with an estimated summary RR of 0.98 for a change of >75th versus <25th percentile in E2 (95% CI 0.74 to 1.31). Mean body mass index (BMI) of the study population (ßs -0.8, p<0.004), and quality of E2 assay (ßs -0.6, p<0.08) may have modified the relationship between E2 and incident CVD. The present systematic review does not provide evidence for a pronounced harmful or beneficial effect of E2 on risk for incident CVD in healthy men. If present, an effect of E2 on risk for CVD might be modulated by BMI.

Heat shock protein 60 as a mediator of adipose tissue inflammation and insulin resistance.

The stress protein heat shock protein 60 (Hsp60) induces secretion of proinflammatory mediators from murine adipocytes. This study aimed to study Hsp60 as a mediator of adipose tissue inflammation and skeletal muscle cell (SkMC) insulin sensitivity and to quantify plasma Hsp60 concentrations in lean and obese individuals. Regulation of Hsp60 release and Hsp60-induced cytokine secretion and signaling was measured in human adipocytes and SkMCs. Adipocytes exhibited higher Hsp60 release than preadipocytes and SkMCs, which was further stimulated by cytokines and Toll-like receptor (TLR)-4 activation. Hsp60 activated extracellular signal-related kinase (ERK)-1/2, Jun NH(2)-terminal kinase (JNK), p38, nuclear factor (NF)-κB, and impaired insulin-stimulated Akt phosphorylation in adipocytes. Furthermore, Hsp60 stimulated adipocytes to secrete tumor necrosis factor-α, interleukin (IL)-6, and IL-8. In SkMCs, Hsp60 activated ERK1/2, JNK, and NF-κB and inhibits insulin signaling and insulin-stimulated glucose uptake. SkMCs released IL-6, IL-8, and monocyte chemoattractant protein-1 on Hsp60 stimulation. Plasma Hsp60 was higher in obese males than in lean males and correlated positively with BMI, blood pressure, leptin, and homeostasis model assessment-insulin resistance. In summary, Hsp60 is released by human adipocytes, increased in plasma of obese humans, and induces insulin resistance. This is accompanied by activation of proinflammatory signaling in human adipocytes and SkMCs. Thus, Hsp60 might be a factor underlying adipose tissue inflammation and obesity-associated metabolic disorders.

Oral bioavailability of moxifloxacin after Roux-en-Y gastric bypass surgery.

OBJECTIVES: Roux-en-Y gastric bypass surgery is the most commonly performed procedure for the treatment of morbid obesity. This anatomical alteration may affect the absorption and consequently the bioavailability of oral drugs. This study aims to investigate the oral bioavailability of moxifloxacin in 12 healthy volunteers who underwent gastric bypass surgery. PATIENTS AND METHODS: In this randomized crossover study, each subject received two single standard doses of 400 mg of moxifloxacin orally or intravenously administered on two occasions separated by a washout period of 1 week. Serial venous blood samples were drawn up to 72 h after dosing and moxifloxacin plasma levels were measured by a validated HPLC method with fluorescence detection. [clinicaltrials.gov database (identifier: NCT01130922).] RESULTS: After oral dosing, moxifloxacin plasma concentrations reached a maximum (C(max)) of 3.38 ± 1.41 mg/L after 1.75 h (0.75-4.00). After intravenous dosing, C(max) and T(max) were 4.53 ± 1.43 mg/L and 1.03 h (0.75-2.50), respectively. The mean areas under the plasma concentration time curve extrapolated to infinity (AUC(∞)) were 46.2 ± 1.4 mg ·â€Šh/L after oral dosing and 52.3 ± 1.3 mg ·â€Šh/L after intravenous dosing, resulting in a mean oral bioavailability of 88.32% [90% confidence interval (CI) 85.64%-91.08%]. CONCLUSIONS: This study confirms that exposure to moxifloxacin is equivalent for oral and intravenous administration of 400 mg dosages in healthy volunteers who underwent gastric bypass surgery. But these exposures were more than 50% higher than those described for subjects without gastric bypass. This may suggest a higher enterohepatic recirculation of moxifloxacin after gastric bypass.

Identification and validation of novel adipokines released from primary human adipocytes.

Adipose tissue is a major endocrine organ, releasing signaling and mediator proteins, termed adipokines, via which adipose tissue communicates with other organs. Expansion of adipose tissue in obesity alters adipokine secretion, which may contribute to the development of metabolic diseases. Although recent profiling studies have identified numerous adipokines, the amount of overlap from these studies indicates that the adipokinome is still incompletely characterized. Therefore, we conducted a complementary protein profiling on concentrated conditioned medium derived from primary human adipocytes. SDS-PAGE/liquid chromatography-electrospray ionization tandem MS and two-dimensional SDS-PAGE/matrix-assisted laser desorption ionization/time of flight MS identified 347 proteins, 263 of which were predicted to be secreted. Fourty-four proteins were identified as novel adipokines. Furthermore, we validated the regulation and release of selected adipokines in primary human adipocytes and in serum and adipose tissue biopsies from morbidly obese patients and normal-weight controls. Validation experiments conducted for complement factor H, αB-crystallin, cartilage intermediate-layer protein, and heme oxygenase-1 show that the release and expression of these factors in adipocytes is regulated by differentiation and stimuli, which affect insulin sensitivity, as well as by obesity. Heme oxygenase-1 especially reveals to be a novel adipokine of interest. In vivo, circulating levels and adipose tissue expression of heme oxygenase-1 are significantly increased in obese subjects compared with lean controls. Collectively, our profiling study of the human adipokinome expands the list of adipokines and further highlights the pivotal role of adipokines in the regulation of multiple biological processes within adipose tissue and their potential dysregulation in obesity.

Combined gene and protein expression of hormone-sensitive lipase and adipose triglyceride lipase, mitochondrial content, and adipocyte size in subcutaneous and visceral adipose tissue of morbidly obese men.

AIMS: Lipotoxicity in obesity might be a failure of adipocytes to respond sufficiently adequate to persistent energy surplus. To evaluate the role of lipolytic enzymes or mitochondria in lipotoxicity, we studied expression levels of genes and proteins involved in lipolysis and mitochondrial DNA (mtDNA) content. METHODS: As differences in lipid metabolism between men and women are extremely complex, we recruited only men (lean and morbidly obese) and collected subcutaneous and visceral adipose tissue during abdominal surgery for real-time PCR gene expression, protein expression, and microscopic study. RESULTS: Although mRNA levels of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) were increased in visceral adipose tissue of morbidly obese men, this was not paralleled by alterations in protein expression and phosphorylation of HSL and ATGL. mtDNA content of visceral adipose tissue was increased in morbidly obese men as compared to lean controls (p < 0.013). Positive correlations were observed between visceral adipocyte size and serum triacylglycerol (r = 0.6, p < 0.007) as well as between visceral adipocyte size and CRP (r = 0.6, p < 0.009) in analyses performed separately in obese men. CONCLUSION: Lipotoxicity of morbidly obese men might be related to the quantitative impact of the visceral fat depot rather than to important dysregulation of involved lipolytic enzymes or adipocyte mitochondria.

Mediators of physical activity change in a behavioral modification program for type 2 diabetes patients.

BACKGROUND: Many studies have reported significant behavioral impact of physical activity interventions. However, few have examined changes in potential mediators of change preceding behavioral changes, resulting in a lack of information concerning how the intervention worked. Our purpose was to examine mediation effects of changes in psychosocial variables on changes in physical activity in type 2 diabetes patients. METHODS: Ninety-two patients (62 ± 9 years, 30, 0 ± 2.5 kg/m(2), 69% males) participated in a randomized controlled trial. The 24-week intervention was based on social-cognitive constructs and consisted of a face-to-face session, telephone follow-ups, and the use of a pedometer. Social-cognitive variables and physical activity (device-based and self-reported) were collected at baseline, after the 24-week intervention and at one year post-baseline. PA was measured by pedometer, accelerometer and questionnaire. RESULTS: Post-intervention physical activity changes were mediated by coping with relapse, changes in social norm, and social modeling from family members (p ≤ 0.05). One-year physical activity changes were mediated by coping with relapse, changes in social support from family and self-efficacy towards physical activity barriers (p ≤ 0.05) CONCLUSIONS: For patients with type 2 diabetes, initiatives to increase their physical activity could usefully focus on strategies for resuming regular patterns of activity, on engaging family social support and on building confidence about dealing with actual and perceived barriers to activity. TRIAL REGISTRATION: NCT00903500, ClinicalTrials.gov.

Dipeptidyl peptidase 4 is a novel adipokine potentially linking obesity to the metabolic syndrome.

OBJECTIVE: Comprehensive proteomic profiling of the human adipocyte secretome identified dipeptidyl peptidase 4 (DPP4) as a novel adipokine. This study assessed the functional implications of the adipokine DPP4 and its association to the metabolic syndrome. RESEARCH DESIGN AND METHODS: Human adipocytes and skeletal and smooth muscle cells were used to monitor DPP4 release and assess the effects of soluble DPP4 on insulin signaling. In lean and obese subjects, depot-specific expression of DPP4 and its release from adipose tissue explants were determined and correlated to parameters of the metabolic syndrome. RESULTS: Fully differentiated adipocytes exhibit a substantially higher release of DPP4 compared with preadipocytes or macrophages. Direct addition of DPP4 to fat and skeletal and smooth muscle cells impairs insulin signaling. A fivefold higher level of DPP4 protein expression was seen in visceral compared with subcutaneous fat of obese patients, with no regional difference in lean subjects. DPP4 serum concentrations significantly correlated with adipocyte size. By using adipose tissue explants from lean and obese subjects, we observed a twofold increase in DPP4 release that strongly correlated with adipocyte volume and parameters of the metabolic syndrome and was decreased to the lean level after weight reduction. DPP4 released from adipose tissue correlated positively with an increasing risk score for the metabolic syndrome. CONCLUSIONS: DPP4 is a novel adipokine that may impair insulin sensitivity in an autocrine and paracrine fashion. Furthermore, DPP4 release strongly correlates with adipocyte size, potentially representing an important source of DPP4 in obesity. Therefore, we suggest that DPP4 may be involved in linking adipose tissue and the metabolic syndrome.

Does low testosterone affect adaptive properties of adipose tissue in obese men?

Obesity and (pre)diabetes in males is associated with low serum testosterone and increased oestradiol levels. It is unknown whether these changes in sex steroids are part of a vicious circle resulting in an increase of risk for metabolic complications of obesity, or whether it presents merely an epiphenomenon. The risk for metabolic complications in obesity seems to be determined by adaptation and integrity of adipose tissue. It is unknown whether the typical changes in sex steroids seen in obese men are desirable or ominous with respect to these functions. However, it might be clinically relevant, as low serum testosterone can be treated, and well with different forms of interventional therapy. The present review provides a short summary on findings, obstacles and future research needed to gain better insight into consequences of changes in sex steroids for adaptation of adipose tissue in obese men.

Sex steroids affect triglyceride handling, glucose-dependent insulinotropic polypeptide, and insulin sensitivity: a 1-week randomized clinical trial in healthy young men.

OBJECTIVE: To evaluate metabolic effects of sex steroids in nonfasting and fasting conditions, independent from changes in body composition. RESEARCH DESIGN AND METHODS: A randomized clinical trial was performed to create contrasting sex steroid levels in healthy young men: by letrozole (aromatase inhibitor) to lower estradiol (E(2)) and increase testosterone (group T, n = 10) versus letrozole plus E(2) patches to lower T and raise E(2) (group E, n = 10). Mixed meals and hyperinsulinemic-euglycemic clamps were performed before and after a 1-week treatment period. RESULTS: Following intervention, the postprandial triglyceride response displayed a diverging response with a decline in group T and an increase in group E; the postprandial glucose-dependent insulinotropic polypeptide (GIP) response increased in group T. Insulin sensitivity increased in group T but remained unaltered in group E. CONCLUSIONS: In healthy young men, short-term changes in sex steroids affect postprandial triglyceride and GIP response and insulin sensitivity.

Birth weight in relation to sex steroid status and body composition in young healthy male siblings.

CONTEXT: Sex steroid concentrations have a strong genetic determination, but environmental factors and body composition play an important role. From studies in children with intrauterine growth restriction, low birth weight has been associated with altered gonadotropin concentrations. OBJECTIVE: We aim to investigate sex steroid concentrations in healthy young brothers in relation to birth weight (normal gestational age), body composition, and parental steroid concentrations. DESIGN AND SETTING: We conducted a cross-sectional, population-based sibling pair study with inclusion of parental data. PARTICIPANTS: A total of 677 men (25-45 yr old) were included in this study, with 296 independent pairs of brothers and 122 fathers. MAIN OUTCOMES: We measured testosterone, estradiol, leptin, adiponectin, IGF-I (immunoassays), and free steroid hormones (calculated) in relation to birth weight and changes in body composition (dual-energy x-ray absorptiometry). RESULTS: Birth weight was associated with serum testosterone (P = 0.0004) and SHBG (P = 0.0001), independent from weight, age, or fat mass, whereas no association with (free) estradiol, LH, or FSH was found. Paternal testosterone (P = 0.02), estradiol (P = 0.04), and SHBG (P = 0.0004) were associated with the respective sex steroid concentrations in the brothers. Weight increase (population rank) during life, was associated with lower testosterone (-15%; P < 0.001), independent from current weight and with higher free estradiol concentrations (+8%; P = 0.002), whereas weight decrease was associated with higher testosterone (+13%; P < 0.001). CONCLUSION: Birth weight and paternal steroid concentrations are associated with testosterone concentrations, independent from adult weight. These findings support the concept of in utero programming across the range of birth weight.

Opposite effects of insulin-like molecules and leptin in coronary heart disease of type 2 diabetes Preliminary data.

INTRODUCTION: Leptin and insulin have been reported to be risk factors for coronary heart disease (CHD) in the general population, but their role in type 2 diabetes still remains unclear. MATERIALS AND METHODS: The role of leptin and insulin upon CHD in type 2 diabetes was assessed in 154 patients, aged 31-77 years, who were treated with oral anti-diabetic agents. Multivariate logistic regression analyses were used with CHD (an established history of CHD or an abnormal treadmill test) as dependent, and leptin, insulin and potential confounders as independent variables. RESULTS: Endogenous insulin was significantly associated with CHD in a model controlling for gender, age, duration of diabetes, body mass index, smoking and leptin (Odds ratio 1.45 per decile, 95% confidence interval 1.11-1.90). Improving control for confounding by replacing body mass index by subcutaneous fat (CT-measured at the L4-L5 level) and height in this model, resulted in a significant negative association between leptin and CHD (OR 0.60, 95% CI 0.37-0.96). DISCUSSION: Leptin might have a beneficial effect on CHD in type 2 diabetes, probably by counteracting the effect of insulin-like molecules or insulin resistance. The effect was elucidated only after careful control for confounding by subcutaneous fat, the main source of leptin production.