Estradiol regulates brown adipose tissue thermogenesis via hypothalamic AMPK

Copyright © 2014 Elsevier Inc. All rights reserved.Peer reviewedPublisher PD

Association of polymorphisms in the beta-2 adrenergic receptor gene with fracture risk and bone mineral density

Summary: Signaling through the beta-2 adrenergic receptor (B2AR) on the osteoblast influences bone remodeling in rodents. In the B2AR gene, three polymorphisms influence receptor function. We show that these polymorphisms are not associated with fracture risk or bone mineral density in the UCP, Rotterdam Study, and GEFOS cohorts. Introduction: Signaling through the beta-2 adrenergic receptor (B2AR) on the osteoblast influences bone remodeling in rodents. In the B2AR gene, three polymorphisms are known to influence receptor function in vitro and in vivo (rs1042713, rs1042714, and rs1800888). We examined the role of these polymorphisms in the B2AR gene on human bone metabolism. Methods: We performed nested case–control studies to determine the association of these polymorphisms with fracture risk in the Utrecht Cardiovascular Pharmacogenetics (UCP) cohort and in three cohorts of the Rotterdam Study. We also determined the association of these polymorphisms with bone mineral density (BMD) in the GEFOS Consortium. UCP contains drug-dispensing histories from community pharmacies linked to national registrations of hospital discharges in the Netherlands. The Rotterdam Study is a prospective cohort study investigating demographics and risk factors of chronic diseases. GEFOS is a large international collaboration studying the genetics of osteoporosis. Fractures were defined by ICD-9 codes 800–829 in the UCP cohort (158 cases and 2617 unmatched controls) and by regular X-ray examinations, general practitioner, and hospital records in the Rotterdam Study (2209 cases and 8559 unmatched controls). BMD was measured at the femoral neck and lumbar spine using dual-energy X-ray absorptiometry in GEFOS (N = 32,961). Results: Meta-analysis of the two nested case–control studies showed pooled odds ratios of 0.98 (0.91–1.05, p = 0.52), 1.04 (0.97–1.12, p = 0.28), and 1.16 (0.83–1.62, p = 0.38) for the associations betwee

Quantitative In Vivo Magnetic Resonance Spectroscopy Using Synthetic Signal Injection

Accurate conversion of magnetic resonance spectra to quantitative units of concentration generally requires compensation for differences in coil loading conditions, the gains of the various receiver amplifiers, and rescaling that occurs during post-processing manipulations. This can be efficiently achieved by injecting a precalibrated, artificial reference signal, or pseudo-signal into the data. We have previously demonstrated, using in vitro measurements, that robust pseudo-signal injection can be accomplished using a second coil, called the injector coil, properly designed and oriented so that it couples inductively with the receive coil used to acquire the data. In this work, we acquired nonlocalized phosphorous magnetic resonance spectroscopy measurements from resting human tibialis anterior muscles and used pseudo-signal injection to calculate the Pi, PCr, and ATP concentrations. We compared these results to parallel estimates of concentrations obtained using the more established phantom replacement method. Our results demonstrate that pseudo-signal injection using inductive coupling provides a robust calibration factor that is immune to coil loading conditions and suitable for use in human measurements. Having benefits in terms of ease of use and quantitative accuracy, this method is feasible for clinical use. The protocol we describe could be readily translated for use in patients with mitochondrial disease, where sensitive assessment of metabolite content could improve diagnosis and treatment

Considérations sur la douleur myofasciale

Caractéristiques de la douleur myofasciale. Traitement

Imaging of serotonin transporters with [I-123]FP-CIT SPECT in the human hypothalamus

Background: Serotonergic neurons in the rodent hypothalamus are implicated in key neuroendocrine and metabolic functions, including circadian rhythmicity. However, the assessment of the serotonergic system in the human hypothalamus in vivo is difficult as delineation of the hypothalamus is cumbersome with conventional region-of-interest analysis. In the present study, we aimed to develop a method to visualize serotonin transporters (SERT) in the hypothalamus. Additionally, we tested the hypothesis that hypothalamic SERT binding ratios are different between patients with hypothalamic impairment (HI), pituitary insufficiency (PI), and control subjects (C). Methods: SERT availability was determined in 17 subjects (6 HI, 5 PI, and 6 healthy controls), 2 h after injection of I-123-N-omega-fluoropropyl-2 beta-carboxymethoxy-3 beta-(4-iodophenyl) nortropane ([I-123]FP-CIT), using single-photon emission computed tomography (performed on a brain-dedicated system) fused with individual magnetic resonance imaging (MRI) scans of the brain. The hypothalamus (representing specific SERT binding) and cerebellum (representing nonspecific binding) were manually delineated on each MRI to assess [I-123]FP-CIT binding and specific-to-nonspecific binding ratios. Results: In each healthy subject, [I-123]FP-CIT binding was higher in the hypothalamus than in the cerebellum, and the mean hypothalamic binding ratio of SERT was 0.29 +/- 0.23. We found no difference in hypothalamic binding ratios between HI, PI, and control subjects (HI 0.16 +/- 0.24, PI 0.45 +/- 0.39, C 0.29 +/- 0.23, p value 0.281). Conclusions: We were able to demonstrate SERT binding in the human hypothalamus However, we did not find altered hypothalamic SERT binding in patients with hypothalamic impairmen

Molecular basis determining species specificity for TLR2 inhibition by staphylococcal superantigen-like protein 3 (SSL3)

Abstract Staphylococcus aureus is a versatile opportunistic pathogen, causing disease in human and animal species. Its pathogenicity is linked to the ability of S. aureus to secrete immunomodulatory molecules. These evasion proteins bind to host receptors or their ligands, resulting in inhibitory effects through high affinity protein–protein interactions. Staphylococcal evasion molecules are often species-specific due to differences in host target proteins between species. We recently solved the crystal structure of murine TLR2 in complex with immunomodulatory molecule staphylococcal superantigen-like protein 3 (SSL3), which revealed the essential residues within SSL3 for TLR2 inhibition. In this study we aimed to investigate the molecular basis of the interaction on the TLR2 side. The SSL3 binding region on murine TLR2 was compared to that of other species through sequence alignment and homology modeling, which identified interspecies differences. To examine whether this resulted in altered SSL3 activity on the corresponding TLR2s, bovine, equine, human, and murine TLR2 were stably expressed in HEK293T cells and the ability of SSL3 to inhibit TLR2 was assessed. We found that SSL3 was unable to inhibit bovine TLR2. Subsequent loss and gain of function mutagenesis showed that the lack of inhibition is explained by the absence of two tyrosine residues in bovine TLR2 that play a prominent role in the SSL3–TLR2 interface. We found no evidence for the existence of allelic SSL3 variants that have adapted to the bovine host. Thus, within this paper we reveal the molecular determinants of the TLR2–SSL3 interaction which adds to our understanding of staphylococcal host specificity

Dose Dependency and a Functional Cutoff for TPO-Antibody Positivity During Pregnancy

Objective: To investigate a dose dependency of thyroperoxidase antibody (TPOAb) concentrations in relation to thyroid function and premature delivery and define a population-based, pregnancy-specific, functional cutoff for TPOAb positivity. Design: Individual participant meta-analysis of three prospective birth cohorts: the Amsterdam Born Children and their Development study, and the Holistic Approach to Pregnancy. Setting: Population-based studies in the Netherlands (2002 to 2014). Participants: A total of 11,212 pregnant women (2.5 mU/L (range, 19.4% to 51.3%). Stratified analyses showed that women with TPOAb concentrations below manufacturer cutoffs already had a higher risk of premature delivery, especially when TSH concentrations were high or in the high-normal range. Conclusions: This study demonstrated a dose-dependent relationship between TPOAbs and thyroid function as well as the risk of premature delivery. Furthermore, our results indicate that the currently used cutoffs for TPOAb positivity may be too high. Furthermore, the use of a population-based cutoff for TPOAbs may identify women with a clinically relevant extent of thyroid autoimmunity and a higher risk of premature delivery but that would not be considered TPOAb positive or eligible for treatment otherwise

Effects of intravenous thyrotropin-releasing hormone on18F-fluorodeoxyglucose uptake in human brown adipose tissue: a randomized controlled trial

Objective: Brown adipose tissue (BAT) activity in humans is stimulated by cold and by a limited number of pharmacological agents, including β3-adrenergic agonists and bile acids. Although thyrotropin-releasing hormone (TRH) is known to activate BAT in several mammals, this has not been reported in humans. Design: A randomized, placebo-controlled, double-blind, cross-over trial. Methods: We investigated the effects of intravenous bolus administration of 400µg TRH or 2mL saline on BAT activity in healthy, lean men. BAT activity was measured as standardized18F-fluorodeoxyglucose (18F-FDG) uptake and glucose metabolic rate (MRglu) using dynamic PET/CT imaging. The first six individuals were studied at room temperature, while subsequently nine were exposed to mild cold (17°C±1°C) for 60min before imaging. During the dynamic scan, blood was withdrawn for measurement of thyroid hormone and catecholamine concentrations. This trial is registered with The Netherlands National Trial Register (number NTR5512). Results: Sixteen participants were recruited. Six men studied at room temperature showed no visible BAT activity during either session. After exposure to mild cold, four of nine men (44.4%) showed clear increase of18F-FDG uptake after TRH administration compared to placebo. Maximal standardized18F-FDG uptake showed a trend toward increase after TRH compared to placebo (P=0.066). MRglu showed a significant increase after TRH administration (P=0.014). The increase in18F-FDG uptake was not paralleled by changes in plasma thyroid hormone or catecholamine concentrations. Conclusion: Systemic TRH administration can increase the activity of cold-stimulated BAT in adult men. These findings may assist developing pharmacological strategies for modulating BAT activity in the management of obesity