Validation of ultrasound estimates of visceral fat in black South African adolescents

Accurate quantification of visceral adipose tissue (VAT) is needed to understand ethnic variations and their implications for metabolic disease risk. The use of reference methods such as computed tomography (CT) and magnetic resonance imaging (MRI) is limited in large epidemiological studies. Surrogate measures such as anthropometry and dual-energy X-ray absorptiometry (DXA) do not differentiate between VAT and subcutaneous abdominal adipose tissue (SCAT). Ultrasound provides a validated estimate of VAT and SCAT in white populations. This study aimed to validate the use of ultrasound-based assessment of VAT in black South African adolescents. One hundred healthy adolescents (boys = 48, girls = 52) aged 18-19 years participating in the birth to twenty cohort study had VAT and SCAT measured by single slice MRI at L4. These MRI "criterion measures" were related to ultrasound VAT and SCAT thickness, anthropometry (BMI, waist and hip circumferences), and DXA android region fat. Ultrasound VAT thickness showed the strongest correlations with MRI VAT (Spearman's correlation coefficients: r = 0.72 and r = 0.64; in boys and girls, respectively), and substantially improved the estimation of MRI VAT compared to anthropometry and DXA alone; in regression models the addition of ultrasound VAT thickness to models containing BMI, waist, and DXA android fat improved the explained variance in VAT from 39% to 60% in boys, and from 31% to 52% in girls. In conclusion, ultrasound substantially increased the precision of estimating VAT beyond anthropometry and DXA alone. Black South African adolescents have relatively little VAT compared to elderly whites, and we therefore provide new ultrasound-based prediction equations for VAT specific to this group.     

The FAt Spondyloarthritis Spine Score (FASSS): development and validation of a new scoring method for the evaluation of fat lesions in the spine of patients with axial spondyloarthritis

Introduction

Studies have shown that fat lesions follow resolution of inflammation in the spine of patients with axial spondyloarthritis (SpA). Fat lesions at vertebral corners have also been shown to predict development of new syndesmophytes. Therefore, scoring of fat lesions in the spine may constitute both an important measure of treatment efficacy as well as a surrogate marker for new bone formation. The aim of this study was to develop and validate a new scoring method for fat lesions in the spine, the Fat SpA Spine Score (FASSS), which in contrast to the existing scoring method addresses the localization and phenotypic diversity of fat lesions in patients with axial SpA.

Methods

Fat lesions at pre-specified anatomical locations at each vertebral endplate (C2 lower-S1 upper) were assessed dichotomously (present/absent) on spine MRIs. Two readers independently evaluated MRIs obtained at two time points for 58 patients (Exercise 1), followed by optimization of scoring methodology and reader calibration. Thereafter, the same readers read 135 pairs of MRI scans (Exercise 2; including the 58 pairs from exercise 1 randomly mixed with 77 new pairs).

Results

In Exercise 2, the mean (SD) baseline FASSS score for the two readers was 22.5(29.6) and 21.1(28.0), respectively, and the FASSS change score was 4.2(10.6) and 6.0(12.2). Inter-reader reliability assessed as intra-class correlation coefficients (ICCs) for status and change scores were excellent (0.96 (95% CI (0.94 to 0.97)) and very good (0.86 (0.80 to 0.90)), respectively. The smallest detectable change (SDC) was 3.7 for the 135 patients. Good reliability of change scores was also observed for MRI scans conducted one year apart (ICC 0.74 (95% CI 0.44 to 0.89) and SDC 4.5). For the 58 MRI-pairs assessed in both exercises, inter-reader reproducibility for the total FASSS status score improved from very good (ICCs: 0.89 (95% CI: 0.81 to 0.93) in exercise 1 to excellent in exercise 2 (0.96 (0.93 to 0.98)), and improved substantially for the total change score (from 0.67 (0.51 to 0.80) to 0.83 (0.73 to 0.90).

Conclusions

FASSS meets essential validation criteria for quantification of a common structural abnormality in clinical trials of axial spondyloarthritis.     

Identification of a novel series of BET family bromodomain inhibitors: binding mode and profile of I-BET151 (GSK1210151A)

A novel series of quinoline isoxazole BET family bromodomain inhibitors are discussed. Crystallography is used to illustrate binding modes and rationalize their SAR. One member, I-BET151 (GSK1210151A), shows good oral bioavailability in both the rat and minipig as well as demonstrating efficient suppression of bacterial induced inflammation and sepsis in a murine in vivo endotoxaemia model.     

Regulation of adiponectin by adipose tissue-derived cytokines: in vivo and in vitro investigations in humans

Adiponectin is an adipose tissue-specific protein that is abundantly present in the circulation and suggested to be involved in insulin sensitivity and development of atherosclerosis. Because cytokines are suggested to regulate adiponectin, the aim of the present study was to investigate the interaction between adiponectin and three adipose tissue-derived cytokines (IL-6, IL-8, and TNF-alpha). The study was divided into three substudies as follows: 1) plasma adiponectin and mRNA levels in adipose tissue biopsies from obese subjects [mean body mass index (BMI): 39.7 kg/m2, n = 6] before and after weight loss; 2) plasma adiponectin in obese men (mean BMI: 38.7 kg/m2, n = 19) compared with lean men (mean BMI: 23.4 kg/m2, n = 10) before and after weight loss; and 3) in vitro direct effects of IL-6, IL-8, and TNF-alpha on adiponectin mRNA levels in adipose tissue cultures. The results were that 1) weight loss resulted in a 51% (P < 0.05) increase in plasma adiponectin and a 45% (P < 0.05) increase in adipose tissue mRNA levels; 2) plasma adiponectin was 53% (P < 0.01) higher in lean compared with obese men, and plasma adiponectin was inversely correlated with adiposity, insulin sensitivity, and IL-6; and 3) TNF-alpha (P < 0.01) and IL-6 plus its soluble receptor (P < 0.05) decreased adiponectin mRNA levels in vitro. The inverse relationship between plasma adiponectin and cytokines in vivo and the cytokine-induced reduction in adiponectin mRNA in vitro suggests that endogenous cytokines may inhibit adiponectin. This could be of importance for the association between cytokines (e.g., IL-6) and insulin resistance and atherosclerosis.     

Molecular Cloning and Functional Expression of the Equine K+ Channel KV11.1 (Ether à Go-Go-Related/KCNH2 Gene) and the Regulatory Subunit KCNE2 from Equine Myocardium

The KCNH2 and KCNE2 genes encode the cardiac voltage-gated K⁺ channel K_V11.1 and its auxiliary β subunit KCNE2. K_V11.1 is critical for repolarization of the cardiac action potential. In humans, mutations or drug therapy affecting the K_V11.1 channel are associated with prolongation of the QT intervals on the ECG and increased risk of ventricular tachyarrhythmia and sudden cardiac death—conditions known as congenital or acquired Long QT syndrome (LQTS), respectively. In horses, sudden, unexplained deaths are a well-known problem. We sequenced the cDNA of the KCNH2 and KCNE2 genes using RACE and conventional PCR on mRNA purified from equine myocardial tissue. Equine K_V11.1 and KCNE2 cDNA had a high homology to human genes (93 and 88%, respectively). Equine and human K_V11.1 and K_V11.1/KCNE2 were expressed in Xenopus laevis oocytes and investigated by two-electrode voltage-clamp. Equine K_V11.1 currents were larger compared to human K_V11.1, and the voltage dependence of activation was shifted to more negative values with V_1/2 = -14.2±1.1 mV and -17.3±0.7, respectively. The onset of inactivation was slower for equine K_V11.1 compared to the human homolog. These differences in kinetics may account for the larger amplitude of the equine current. Furthermore, the equine K_V11.1 channel was susceptible to pharmacological block with terfenadine. The physiological importance of K_V11.1 was investigated in equine right ventricular wedge preparations. Terfenadine prolonged action potential duration and the effect was most pronounced at slow pacing. In conclusion, these findings indicate that horses could be disposed to both congenital and acquired LQTS.     

Physical Activity Energy Expenditure of Adolescents in India

Physical activity (PA) has rarely been quantified in adolescent populations undergoing economic transition; therefore relationships with disease still remain uncertain. This study assessed whether absolute PA energy expenditure (PAEE), PAEE/kg, and PAEE/kg_FFM could be accurately estimated using accelerometry and a questionnaire in Indian adolescents and how these values compared to those of other populations. PAEE was assessed using doubly labeled water (DLW) in 30 adolescents from Chennai, India, over seven consecutive days, simultaneous with the measurement of PA using accelerometry and a previous‐week recall questionnaire. Accelerometry counts (regression analysis) and questionnaire data were used to estimate PAEE; estimates were cross‐validated using the Bland‐Altman method. Accelerometry data and DLW‐derived PAEE were visually compared to values from four North American and European populations. For boys, 49% of the variance in DLW‐derived PAEE was explained with an equation including accelerometry counts and fat‐free mass (FFM). Questionnaire‐derived estimates did not contribute to the explained variance in DLW derived PAEE. The group‐level PA of these Indian adolescents was successfully assessed using accelerometry, but not questionnaire. DLW‐derived PAEE/kg_FFM (mean (s.d.): 53.0 (27.5) kJ/kg_FFM/day) was lower in this group than other adolescent populations in Europe and similar to those in North America. Additionally, four boys and none of the girls accumulated ≥60 min/day of accelerometry‐derived moderate intensity activity, indicating low levels of PAEE and PA in these adolescents. Further research is necessary to investigate the association between PA and health outcomes in Indian adolescents.     

Weight Loss,HbA1c Reduction,and Tolerability of Cetilistat in a Randomized,Placebo‐controlled Phase 2 Trial in Obese Diabetics: Comparison With Orlistat (Xenical)

The objective of this multicenter, randomized, double‐blind study was to determine the efficacy and safety of cetilistat and orlistat relative to placebo in obese patients with type 2 diabetes, on metformin. Following a 2‐week run‐in, patients were randomized to placebo, cetilistat (40, 80, or 120 mg three times daily), or orlistat 120 mg t.i.d., for 12 weeks. The primary endpoint was absolute change in body weight from baseline. Secondary endpoints included other measures of obesity and glycemic control. Similar reductions in body weight were observed in patients receiving cetilistat 80 or 120 mg t.i.d. or 120 mg t.i.d. orlistat; these reductions were significant vs. placebo (3.85 kg, P = 0.01; 4.32 kg, P = 0.0002; 3.78 kg, P = 0.008). In the 40 mg t.i.d. and placebo groups, reductions were 2.94 kg, P = 0.958 and 2.86 kg, respectively. Statistically significant reductions in glycosylated hemoglobin (HbA_1c) were noted. Cetilistat was well tolerated, and showed fewer discontinuations due to adverse events (AEs) than in the placebo and orlistat groups. Discontinuation in the orlistat group was significantly worse than in the 120 mg cetilistat and placebo groups and was entirely due to gastrointestinal (GI) AEs. Treatment with cetilistat 80 or 120 mg t.i.d., or with orlistat 120 mg t.i.d., significantly reduced body weight and improved glycemic control relative to placebo in obese diabetic patients. Cetilistat was well tolerated with the number of discontinuations due to AEs being similar to placebo.     

Physical activity attenuates the influence of FTO variants on obesity risk: a meta-analysis of 218,166 adults and 19,268 children

Background

The FTO gene harbors the strongest known susceptibility locus for obesity. While many individual studies have suggested that physical activity (PA) may attenuate the effect of FTO on obesity risk, other studies have not been able to confirm this interaction. To confirm or refute unambiguously whether PA attenuates the association of FTO with obesity risk, we meta-analyzed data from 45 studies of adults (n = 218,166) and nine studies of children and adolescents (n = 19,268).

Methods and Findings

All studies identified to have data on the FTO rs9939609 variant (or any proxy [r ²>0.8]) and PA were invited to participate, regardless of ethnicity or age of the participants. PA was standardized by categorizing it into a dichotomous variable (physically inactive versus active) in each study. Overall, 25% of adults and 13% of children were categorized as inactive. Interaction analyses were performed within each study by including the FTO×PA interaction term in an additive model, adjusting for age and sex. Subsequently, random effects meta-analysis was used to pool the interaction terms. In adults, the minor (A−) allele of rs9939609 increased the odds of obesity by 1.23-fold/allele (95% CI 1.20–1.26), but PA attenuated this effect (p _interaction  = 0.001). More specifically, the minor allele of rs9939609 increased the odds of obesity less in the physically active group (odds ratio  = 1.22/allele, 95% CI 1.19–1.25) than in the inactive group (odds ratio  = 1.30/allele, 95% CI 1.24–1.36). No such interaction was found in children and adolescents.

Conclusions

The association of the FTO risk allele with the odds of obesity is attenuated by 27% in physically active adults, highlighting the importance of PA in particular in those genetically predisposed to obesity. Please see later in the article for the Editors'' Summary     

Sexual selection and speciation in mammals,butterflies and spiders

Recently refined evolutionary theories propose that sexual selection and reproductive conflict could be drivers of speciation. Male and female reproductive optima invariably differ because the potential reproductive rate of males almost always exceeds that of females: females are selected to maximize mate 'quality', while males can increase fitness through mate 'quantity'. A dynamic, sexually selected conflict therefore exists in which 'competitive' males are selected to override the preference tactics evolved by 'choosy' females. The wide variation across taxa in mating systems therefore generates variance in the outcome of intrasexual conflict and the strength of sexual selection: monandry constrains reproductive heterozygosity and allows female choice to select and maintain particular (preferred) genes; polyandry promotes reproductive heterozygosity and will more likely override female choice. Two different theories predict how sexual selection might influence speciation. Traditional ideas indicate that increased sexual selection (and hence conflict) generates a greater diversity of male reproductive strategies to be counteracted by female mate preferences, thus providing elevated potentials for speciation as more evolutionary avenues of male-female interaction are created. A less intuitively obvious theory proposes that increased sexual selection and conflict constrains speciation by reducing the opportunities for female mate choice under polyandry. We use a comparative approach to test these theories by investigating whether two general measures of sexual selection and the potential for sexual conflict have influenced speciation. Sexual size dimorphism (across 480 mammalian genera, 105 butterfly genera and 148 spider genera) and degree of polyandry (measured as relative testes size in mammals (72 genera) and mating frequency in female butterflies (54 genera)) showed no associations with the variance in speciosity. Our results therefore show that speciation occurs independently of sexual selection.     

RIBOSOMAL DNA AND RAPD VARIATION IN THE RARE PLANT FAMILY LACTORIDACEAE

Lactoris fernandeziana, endemic to the island of Masatierra in the Juan Fernandez Archipelago, is the only living member of the primitive angiosperm family, Lactoridaceae. The species was surveyed for ribosomal DNA (rDNA) and RAPD (Random Amplified Polymorphic DNA) variation. Previous analyses of allozymes had revealed no variation within the species. Variation was found for length in the intergenic spacer and for restriction sites in the 18S–25S genes of rDNA, and for the presence of amplified bands using 16 primers. Different rDNA repeat lengths and restriction site variants were detected within individuals as well as within and among populations. The level of variation in RAPDs is low relative to other Juan Fernandez endemic species surveyed, and nearly all variants were restricted to single populations. The rDNA length variants were distributed throughout the island, whereas the rDNA restriction site variants and RAPD markers indicated minor genetic differences among the populations.