Functional Variation in the Androgen-Receptor Gene Is Associated With Visceral Adiposity and Blood Pressure in Male Adolescents

Pathophysiology of primary hypertension in children and adolescents

The progress in research on the physiology of the cardiovascular system made in the last 100 years allowed for the development of the pathogenesis not only of secondary forms of hypertension but also of primary hypertension. The main determinants of blood pressure are described by the relationship between stroke volume, heart rate, peripheral resistance, and arterial stiffness. The theories developed by Guyton and Folkow describe the importance of the volume factor and total peripheral resistance. However, none of them fully presents the pathogenesis of essential hypertension. The multifactorial model of primary hypertension pathogenesis developed by Irving Page in the 1940s, called Page's mosaic, covers most of the pathophysiological phenomena observed in essential hypertension. The most important pathophysiological phenomena included in Page's mosaic form a network of interconnected "nodes". New discoveries both from experimental and clinical studies made in recent decades have allowed the original Page mosaic to be modified and the addition of new pathophysiological nodes. Most of the clinical studies confirming the validity of the multifactorial pathogenesis of primary hypertension concern adults. However, hypertension develops in childhood and is even perinatally programmed. Therefore, the next nodes in Page's mosaic should be age and perinatal factors. This article presents data from pediatric clinical trials describing the most important pathophysiological processes associated with the development of essential hypertension in children and adolescents.

Association between body composition and blood pressure in normal-weight Chinese children and adolescents

Background

The aim of this study was to assess the associations of body fat distribution and lean body mass (LBM) with blood pressure (BP) in normal-weight Chinese children and adolescents.

Methods

A total of 898 normal-weight Chinese children and adolescents, aged 10–18 years, were included this cross-sectional study via a cluster sampling method. The bioelectrical impedance analysis (BIA) was used to measure body composition. The participants were measured for blood pressure (BP) using a calibrated electronic sphygmomanometer according to the standard method by the "American Hypertension Education Project Working Group".

Results

Body composition was related to abnormal BP in normal-weight children and adolescents. After the model adjusted for age, smoking, and drinking, regression analysis showed that fat mass percentage (FMP) was negatively associated with abnormal BP, while LBM was positively associated with abnormal BP in boys(P < 0.05). Whereas FMP and visceral fat level (VFL) were positively associated with abnormal BP in girls (P < 0.05).

Conclusions

There are sex differences in the relationships between total body fat, visceral fat and lean body mass with abnormal BP in normal-weight youths. Therefore, it is of great significance to pay attention to the relative influence of the body composition of the boys and girls in the prevention and treatment of hypertension in youths.

Comparative Transcriptome Analysis Provides Insight into Spatio-Temporal Expression Characteristics and Genetic Regulatory Network in Postnatal Developing Subcutaneous and Visceral Fat of Bama Pig

The depot differences between Subcutaneous Fat (SAF) and Visceral Fat (VAF) are critical for human well-being and disease processes in regard to energy metabolism and endocrine function. Miniature pigs (Sus scrofa) are ideal biomedical models for human energy metabolism and obesity due to the similarity of their lipid metabolism with that of humans. However, the regulation of differences in fat deposition and development remains unclear. In this study, the development of SAF and VAF was characterized and compared in Bama pig during postnatal development (infancy, puberty and adulthood), using RNA sequencing techniques (RNA-Seq). The transcriptome of SAF and VAF was profiled and isolated from 1-, 3- and 6 months-old pigs and identified 23,636 expressed genes, of which 1,165 genes were differentially expressed between the depots and/or developmental stages. Upregulated genes in SAF showed significant function and pathway enrichment in the central nervous system development, lipid metabolism, oxidation-reduction process and cell adhesion, whereas genes involved in the immune system, actin cytoskeleton organization, male gonad development and the hippo signaling pathway were preferentially expressed in VAF. Miner analysis of short time-series expression demonstrated that differentiation in gene expression patterns between the two depots corresponded to their distinct responses in sexual development, hormone signaling pathways, lipid metabolism and the hippo signaling pathway. Transcriptome analysis of SAF and VAF suggested that the depot differences in adipose tissue are not only related to lipid metabolism and endocrine function, but are closely associated with sexual development and organ size regulation.

Obesity in childhood: how to improve male adolescence incoming

INTRODUCTION

Earlier or delayed puberty can be determined by numerous causes, but the exact mechanisms are not fully known. Anyway, those may be independent from the hypothalamicpituitary-gonadal axis involvement. Certainly, obesity is one of the main factors. In fact, obesity and infertility are strongly linked. For this reason, we want to analyse the relationship between puberty and obesity and give an updated state-of-the-art starting by discussing a 14-year-old obese boy's clinical case.

EVIDENCE ACQUISITION

Literature data are conflicting. Main criticisms are related to study design and evaluation criteria. Indeed, examined populations are not homogeneous by age, Tanner stage and BMI classification. The obesity epidemic is involved in earlier puberty, and puberty seems to be anticipated in all BMI groups. Very few studies evaluate the level of adiposity in the diagnosis of obesity. However, the role of the adipose tissue is crucial for hormone synthesis and regulation. Therefore, fat mass age-related and not simply BMI has to be considered by clinicians for appropriate diagnosis.

EVIDENCE SYNTHESIS

Regarding the clinical case, in three months our patient recovered delayed pubertal development following an anti-inflammatory and antioxidant Mediterranean Diet. Loss of weight, as in decrease of fat mass but saving of lean mass, increased testicular volume and testosterone levels occurred.

CONCLUSIONS

Puberty depends on several factors, including obesity. Further studies are needed to evaluate age groups, Tanner stage, diet and lifestyle, ethnicity and above all the fat/lean mass ratio. Lack of adequate tools could hinder a clinician's ability to recognize when or if therapeutic intervention is needed.

Characterization of mice bearing humanized androgen receptor genes (h/mAr) varying in polymorphism length

The androgen receptor (AR) is known for masculinization of behavior and brain. To better understand the role that AR plays, mice bearing humanized Ar genes with varying lengths of a polymorphic N-terminal glutamine (Q) tract were created (Albertelli et al., 2006). The length of the Q tract is inversely proporitional to AR activity. Biological studies of the Q tract length may also provide a window into potential AR contributions to sex-biases in disease risk. Here we take a multi-pronged approach to characterizing AR signaling effects on brain and behavior in mice using the humanized Ar Q tract model. We first map effects of Q tract length on regional brain anatomy, and consider if these are modified by gonadal sex. We then test the notion that spatial patterns of anatomical variation related to Q tract length could be organized by intrinsic spatiotemporal patterning of AR gene expression in the mouse brain. Finally, we test influences of Q tract length on four behavioral tests.Altering Q tract length led to neuroanatomical differences in a non-linear dosage-dependent fashion. Gene expression analyses indicated that adult neu- roanatomical changes due to Q tract length are only associated with neurode- velopment (as opposed to adulthood). No significant effect of Q tract length was found on the behavior of the three mouse models. These results indicate that AR activity differentially mediates neuroanatomy and behavior, that AR activity alone does not mediate sex differences, and that neurodevelopmen- tal processes are associated with spatial patterns of volume changes due to Q tract length in adulthood. They also indicate that androgen sensitivity in adulthood is not likely to lead to autism-related behaviors or neuroanatomy, although neurodevelopmental processes may play a role earlier. Further study into sex differences, development, other behaviors, and other sex-specific mech- anisms are needed to better understand AR sensitivity, neurodevelopmental disorders, and the sex difference in their prevalence.

Relación entre nivel de condición física y percepción de la calidad de vida relacionada con la salud en adolescentes del sureste español

Introducción. La condición física relacionada con la salud (CFS) es considerada como uno de los factores que determinan el concepto de calidad de vida relacionada con la salud (CVS).Objetivo. Analizar la relación entre el nivel de CFS y la percepción de la CVS en adolescentes españoles.Materiales y métodos. Estudio multicéntrico realizado en una población de 1 037 adolescentes (15.52±1.11 años) del sureste de España (Región de Murcia). La CFS y la CVS se evaluaron mediante la batería COFISA y el Cuestionario de Salud SF-36, respectivamente.Resultados. La prueba MANOVA mostró que los varones tuvieron un mejor rendimiento físico global (p<0.001). Respecto a la CVS, las mujeres tuvieron una mejor percepción en la dimensión salud general (p=0.011), mientras que la percepción de los varones fue mejor en las dimensiones rol emocional (p=0.010) y salud mental (p<0.001). Los adolescentes con mayor nivel CFS tuvieron valores superiores en la percepción global de la CVS (p<0.001 en todas las variables).Conclusión. La asociación entre niveles altos de CFS y puntajes superiores de percepción de la CVS hace necesario establecer estrategias y acciones que busquen aumentar los niveles de participación de los jóvenes en actividades físicas y deportivas.

Association of triglyceride-glucose index and its interaction with obesity on hypertension risk in Chinese: a population-based study

Hypertension and triglyceride-glucose (TyG) index are both closely associated with insulin resistance, respectively, while the role of TyG index and the association between TyG index and obesity on hypertension risk remain unclear. This study aimed to examine the association and interactive effect of TyG index and obesity on hypertension risk. There was a population-based cross-sectional survey in Henan, China. Multivariate logistic regression analysis was performed to estimate the association between TyG index and the risk of prehypertension and hypertension. The area under curves (AUC) of TyG index and joint indicators (TyG index and obesity indices) was calculated to assess the predictive ability of hypertension. The additive interaction was computed to evaluate the interactive effect between TyG index and obesity. Compared with the lowest TyG quartile, participants in the highest quartile had an increased risk of prehypertension (odds ratio (OR): 1.69, 95% confidence interval (CI): 1.18-2.44) and hypertension (OR: 2.53, 95% CI: 1.80-3.57). The AUCs of joint indicators were significantly higher than TyG index in predicting hypertension (all P < 0.01). Presence of higher TyG index enhanced the ORs of waist-to-height ratio (WHtR) and percent body fat (PBF) from 3.50 (95% CI: 2.55-4.80) to 6.51 (95% CI: 4.81-8.82), and from 3.88 (95% CI: 2.78-5.42) to 7.09 (95% CI: 5.11-9.84) with significant additive interaction on hypertension, respectively. Increased TyG index was significantly associated with a higher risk of prehypertension and hypertension in Chinese adults. Besides, our results also demonstrated the interactions of TyG index and WHtR and PBF on hypertension risk.

Visceral fat reduction is positively associated with blood pressure reduction in overweight or obese males but not females: an observational study

BACKGROUND

Visceral adiposity has been reported to play a key role in hypertension compared with other measurements of regional or general obesity. The aim of current study was to evaluate the relationship between visceral fat reduction and changes in blood pressure in a group of overweight or obese Chinese individuals.

METHODS

An observational study was conducted with 168 participants (ChiCTR-OOC-17012000). Body composition, blood parameters and blood pressure were assessed at the beginning and end of the intervention. Males and females were categorized separately into quartiles according to changes in visceral fat during the intervention. Multiple linear regression models were used to assess the associations of changes in systolic and diastolic blood pressure with changes of visceral fat area, adjusted for potential confounders.

RESULTS

Changes in visceral fat was significantly associated with systolic and diastolic blood pressure in men for systolic (β = 0.234, 95% CI: 0.103, 0.365; p = 0.001) and diastolic blood pressure (β = 0.237; 95% CI: 0.127, 0.346; p <0.001), but not in women after adjustment for the same potential confounders for systolic blood (β = - 0.003, 95% CI: - 0.260, 0.255; p = 0.984) and diastolic blood pressure (β = 0.101, 95% CI: - 0.072, 0.273; p = 0.249).

CONCLUSIONS

A positive association was observed between reduction in visceral fat and improvements in both systolic blood and diastolic blood pressures in males but not females in a 12-week meal replacement intervention.

TRIAL REGISTRATION

The Ethics Committee of Peking University Health Science Center approved the study protocol on 6 July 2017. The authors confirm that all ongoing and related trials for this intervention were carried out following the rules of the Declaration of Helsinki of 1975 and registered (ChiCTR-OOC-17012000). http://www.chictr.org.cn/showprojen.aspx?proj=20426.

Viscus fat area contributes to the Framingham 10-year general cardiovascular disease risk in patients with type 2 diabetes mellitus

OBJECTIVE

To explore the correlation of the viscus fat area (VFA) with the Framingham 10-year general cardiovascular disease risk in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 202 patients with T2DM were divided into two groups based on VFA (a VFA ≥ 100 cm² group and a VFA < 100 cm² group), or four groups based on sex and age (a middle-aged male group, an elderly male group, a middle-aged female group, and an elderly female group). The correlation between the Framingham 10-year general cardiovascular disease risk and body fat indexes was analyzed.

RESULTS

Patients in the VFA ≥ 100 cm² group had higher body fat indexes and Framingham Risk Scores (FRSs) and lower levels of high density lipoprotein-cholesterol (HDL-C) when compared to the VFA < 100 cm² group (P < 0.05). Female patients had higher body fat mass (BFM) and body fat percentage (BFP) levels and a lower VFA when compared to male patients. The VFA was significantly higher in the elderly than in the middle-aged patients. The waist hip fat ratio (WHFR) was significantly higher in elderly females than in elderly males (P < 0.05). Elderly females had the highest FRS of all patients. Multiple stepwise regression analysis revealed the VFA as a contributor to the Framingham 10-year general cardiovascular disease risk after statistical correction for other multiple factors affecting cardiovascular disease risk.

CONCLUSION

The VFA is an independent factor that contributes to the Framingham 10-year general cardiovascular disease risk in patients with T2DM.

Neuroendocrine stress response is moderated by sex and sex hormone receptor polymorphisms

Sex hormones are significant regulators of stress reactivity, however, little is known about how genetic variation in hormone receptors contributes to this process. Here we report interactions between biological sex and repeat polymorphisms in genes encoding sex hormone receptors, and their effects on salivary cortisol reactivity in a sample of 100 participants (47 men & 53 women; 24.7 ± 3.23 years). Three genes were investigated: estrogen receptors alpha (ESR1) and beta (ESR2), and the androgen receptor (AR). Participants were classified as carrying 'Short' or 'Long' alleles based on median splits of the repeat distribution for each gene. Measures of physiological reactivity were collected before and after exposure to a canonical laboratory stressor and converted to traditional summary measures for analyses. Overall, men exhibited greater cortisol (p = 0.001) and mean arterial pressure reactivity (p = 0.002), while women displayed elevated heart rate throughout the session (p = 0.02). The effect of polymorphisms on salivary cortisol was sex sensitive. ESR1 was associated with differential reactivity in men (p = 0.04), but not women (p = 0.24). ESR2 genotype interacted with sex such that each additional 'Long' allele was associated with a 6.4% decrease in salivary cortisol in men, but a 9.5% increase in the levels of women (p = 0.02 for interaction). For the X-linked AR, the 'Long' allele was associated with decreased cortisol levels in men (p = 0.047), but in women had no effect (p = 0.75). Together, these results provide evidence for the saliency of genetic variation in sex hormone receptors on stress reactivity in humans and highlight their important role as mediators of hormonal activity.

Comparison of adiposity indices in relation to prehypertension by age and gender: A community-based survey in Henan, China

BACKGROUND

To compare the efficiency of bioelectrical indices (visceral fat index [VFI], percentage body fat [PBF]) and anthropometric indices (body mass index, waist circumference, waist-to-height ratio, a body shape index ) in the relation to prehypertension (120-139/80-89 mm Hg) among the Chinese population.

METHODS

Using stratified multistage random sampling method, a general population-based sample of 11 175 adults in Henan province were selected from 2013 to 2015. The individuals were divided into three categories by blood pressure levels: normotension (<120 and 80 mm Hg), stage 1 prehypertension (120-129/80-84 mm Hg) and stage 2 prehypertension (130-139/85-89 mm Hg).

RESULTS

VFI and PBF tended to increase with age in men and women. However, for each age-specific group, men tended to have higher VFI than women (all P < 0.01) and women tended to have greater PBF (all P < 0.0001). The odds ratios (OR) and area under the receiver operating characteristic curves for prehypertension associated with adiposity indices declined with age. VFI and PBF showed higher standardized adjusted ORs for prehypertension in young (~40 years) men (VFI: 2.02-3.05; PBF: 1.82-2.80) and young women (VFI: 1.90-2.58; PBF:1.70-2.29). Moreover, based on Youden's index, VFI and PBF exhibited the superiority for identifying prehypertension in men (0.20-0.32) and women (0.31-0.39), respectively.

CONCLUSION

In summary, there was stronger association of VFI and PBF with prehypertension in men than in women, respectively, especially for young adults.

Dose-response relationship between visceral fat index and untreated hypertension in Chinese rural population: the RuralDiab study

The study aimed to explore the association of visceral fat index (VFI) with untreated hypertension in different genders and evaluate the practicability of VFI as a marker for discriminating untreated hypertension in Chinese rural population. A total of 12,536 eligible participants aged 35 years and older were derived from the RuralDiab study in China. VFI was assessed with bioelectrical impendence methods and divided into sex-specific quartiles. Logistic regression and restricted cubic spline regression were performed. Receiver operating characteristic curve was applied to analyze the discriminating performance of VFI. Meanwhile, a meta-analysis was conducted to validate the result of this study. Compared with the lowest VFI quartile, the adjusted odds ratios (ORs) and 95% confidence interval (95% CI) in the highest VFI quartile were 3.68 (2.91-4.66) in male and 2.63 (2.12-3.25) in female (P_trend < .01). Nonlinear increasing trends about the risk of untreated hypertension were observed with the continuously increasing VFI in both genders (P_linearity < .01). The sensitivity and specificity in the optimal cutoff values for VFI were 58.37% and 62.26% in male, and 49.09% and 66.67% in female. The area under the curves (95% CI) were 0.64 (0.63-0.66) in male and 0.61 (0.60-0.62) in female. Meta-analysis results displayed the pooled odds ratios (95% CI) of 2.65 (1.79-3.93) in male and 2.27 (1.74-2.95) in female. VFI was significantly positively correlated with the risk of untreated hypertension, and dose-response relationships were observed in both genders in Chinese rural population. However, VFI as a marker had limited potential for discriminating untreated hypertension.

Androgen receptor CAG repeat polymorphism is not associated with insulin resistance and diabetes among South Asian males

Objective

To study relationship between androgen receptor (AR) CAG repeat polymorphism, insulin resistance (IR), β-cell function and other clinical/biochemical parameters in ethnic South Asian adults. A case (males with diabetes), control (males without diabetes) study, was conducted and 110 males were invited. Anthropometry, blood pressure and biochemical parameters (fasting Insulin, blood sugar, HbA1c and lipid profile) were measured. IR and β-cell function was calculated. A multiple-linear-regression analysis was performed, using number of AR CAG repeats as the continuous dependent variable.

Results

Sample size was 100 (response rate—90.9%, cases—53). Mean age was 49.6 ± 10.7 years. CAG repeat length did not show any significant correlation with IR or β-cell function. In all males there was a significant correlation between number of AR CAG repeats and systolic blood pressure (r = 0.25; p = 0.016), diastolic blood pressure (r = 0.21; p = 0.045), total cholesterol (r = − 0.22; p = 0.037) and low-density lipoprotein cholesterol (r = − 0.22; p = 0.037). Only total cholesterol (β = − 4.41; p < 0.001) and estrogen (β = 2.25; p = 0.03) were significantly associated with number of AR CAG repeats in regression analysis. In conclusion, AR CAG repeat length did not show any significant correlation with IR or β-cell function. Positive association of AR CAG with systolic and diastolic blood pressure and negative association of AR CAG with total and low-density lipoprotein cholesterol deserves further attention.

Cardiometabolic Risk Factors and Health-Related Quality of Life in Adolescents with Obesity

BACKGROUND

A number of research studies have demonstrated a decrease in health-related quality of life (HRQL) measures among obese children. Moreover, the causes of HRQL impairments are not completely clear. Adolescent obesity is oftentimes associated with other cardiometabolic risk factors (CRFs); hence, the aim of our research was to estimate the frequency of CRFs and to determine whether there is an association between CRFs and HRQL scores among obese adolescents.

METHODS

Our research included 92 treatment-seeking obese adolescents (11-17 years), 34 males. We looked at medical records and performed physical examinations, including anthropometry and laboratory evaluations. PedsQL™ 4.0 was used to assess the HRQL score. Logistic regression models were used to identify CRFs associated with worse HRQL scores, both in total and in each domain.

RESULTS

The vast majority (70.6%) of adolescents had at least one CRF in addition to obesity. A cluster of three to four CRFs was found in 23.3% and was associated with males more than with the degree of obesity [odds ratio (OR) 4; confidence interval (95% CI) 1.3-11.6, p = 0.01]. HRQL scores in emotional functioning domain and scores of HRQL total were directly associated with waist circumference Z-score (OR 4.1; 95% CI 1.1-14.9, p = 0.03 and OR 3.4; 95% CI 1-11.6, p = 0.049). Hypertension was associated with worsening HRQL scores in school functioning domain (OR 3.3; 95% CI 1-10.9, p = 0.049).

CONCLUSION

Obesity in adolescents is associated with a high frequency of associated CRFs and decreased HRQL scores. Although CRFs have an influence on reducing adolescents' HRQL, they are not a determining factor.

The polymorphic CAG repeat in exon 1 of androgen receptor is associated with level of HDL cholesterol and hypertension in Chinese middle-aged and elderly men

OBJECTIVE

The length of the CAG repeats in exon 1 of the androgen receptor (AR) gene has been shown to be inversely correlated with AR transcriptional activity. This study aimed to investigate the correlations between the length of CAG repeat in AR and serum lipids and hypertension in Chinese men.

DESIGN AND PATIENTS

The relationship between length of the CAG repeat in exon 1 of AR with prevalence of hypertension and the levels of serum lipids among Chinese men (aged ≥40 years).

MEASUREMENTS

The physical condition of the subjects was examined and recorded. The concentrations of blood lipids and sex hormones were measured, and the CAG repeat lengths of the AR gene were determined.

RESULTS

The length of the AR CAG repeats was associated with HDL cholesterol (HDL-C) concentration, and the stepwise multiple regression model showed that this association was independent of body mass index (BMI), triglycerides (TG) and total cholesterol (TC), although these factors influence HDL-C concentration. Furthermore, men with <22 vs men with ≥22 CAG repeats showed higher blood pressure and higher prevalence of hypertension. Shorter CAG repeat numbers were associated with the increased risk of hypertension in a multivariate logistic regression analysis (odds ratio = 0·715; 95% confidence interval, 0·517-0·989; P = 0·043). No significant correlation of AR CAG repeat polymorphism with sex hormone levels, TG, LDL cholesterol (LDL-C) or TC was found.

CONCLUSIONS

This study provides evidence that men carrying shorter (<22) AR CAG repeats have lower HDL-C level and increased risk of hypertension. The androgenic activity may differ due to the polymorphic length of CAG repeats of the AR gene.

Cohort Profile: The Saguenay Youth Study (SYS)

The Saguenay Youth Study (SYS) is a two-generational study of adolescents and their parents (n = 1029 adolescents and 962 parents) aimed at investigating the aetiology, early stages and trans-generational trajectories of common cardiometabolic and brain diseases. The ultimate goal of this study is to identify effective means for increasing healthy life expectancy. The cohort was recruited from the genetic founder population of the Saguenay Lac St Jean region of Quebec, Canada. The participants underwent extensive (15-h) phenotyping, including an hour-long recording of beat-by-beat blood pressure, magnetic resonance imaging of the brain and abdomen, and serum lipidomic profiling with LC-ESI-MS. All participants have been genome-wide genotyped (with ∼ 8 M imputed single nucleotide polymorphisms) and a subset of them (144 adolescents and their 288 parents) has been genome-wide epityped (whole blood DNA, Infinium HumanMethylation450K BeadChip). These assessments are complemented by a detailed evaluation of each participant in a number of domains, including cognition, mental health and substance use, diet, physical activity and sleep, and family environment. The data collection took place during 2003-12 in adolescents (full) and their parents (partial), and during 2012-15 in parents (full). All data are available upon request.

Androgen receptor GGC repeat might be more involved than CAG repeat in the regulation of the metabolic profile in men

The influence of androgen receptor (AR) GGC repeat polymorphism on the metabolic profile of men has been much less studied than the one of CAG tract polymorphism. Therefore, in this study, we looked for the association of GGC and CAG tract with cardiovascular risk factors in men. Ninety-eight men followed by our andrological unit were retrospectively reviewed. Clinical and biochemical parameters on cardiovascular risk were considered. AR CAG and GGC polymorphisms were studied. GGC triplets were found to be positively and significantly correlated with several cardiovascular risk factors. On the other hand, inverse and significant correlations of CAG triplets were found with insulin and HOMA. As expected, age was positively correlated with cardiovascular risk, whereas total testosterone was inversely correlated with metabolic profile. Estradiol was not found to be correlated with any of the metabolic parameters. In the total sample, multivariate linear regression analysis confirms the positive and independent association of GGC triplets with glycemia, glycated hemoglobin, total cholesterol, triglycerides and homeostasis model assessment of insulin resistance (HOMA), whereas CAG repeat length is negatively associated with insulin and HOMA. Such associations are also substantially confirmed in non-diabetic subjects, whereas in diabetic patients only the GGC tract seems to be involved in the metabolic profile regulation. Our work shows a relevant role for GGC repeat tract in conditioning male cardiovascular risk, thus rendering necessary a deeper analysis on the role of GGC polymorphism both from the molecular and the clinical point of view.

Intra-abdominal fat accumulation is a hypertension risk factor in young adulthood: A cross-sectional study

Accumulation of intra-abdominal fat is related to hypertension. Despite this, a relationship between hypertension and intra-abdominal fat in young adulthood is not clear. In this study, we verify whether intra-abdominal fat accumulation increases a hypertension risk in young adult subjects.In a cross-sectional study, intra-abdominal fat area was measured using a dual bioelectrical impedance analysis instrument in 697 university students (20.3 ± 0.7 years, 425 men). Blood pressure and anthropometric factors were measured. Lifestyle variables including smoking, drinking, physical activity, and eating behavior were assessed with questionnaire. High blood pressure risk (systolic blood pressure ≥130 mm Hg and/or diastolic blood pressure ≥85 mm Hg) with increasing intra-abdominal fat area was evaluated.Participants were divided into 5 groups according to their intra-abdominal fat area (≤24.9, 25-49.9, 50-74.9, 75-99.9, and ≥100 cm). As compared with the values of the smallest intra-abdominal fat area group, the crude and lifestyle-adjusted odds ratios (ORs) were elevated in larger intra-abdominal fat area groups [OR 1.31, 95% confidence interval (CI) 0.66-2.80; OR 3.38, 95% CI 1.60-7.57; OR 7.71, 95% CI 2.75-22.22; OR 18.74, 95% CI 3.93-105.64, respectively). The risk increase was observed only in men.Intra-abdominal fat accumulation is related to high blood pressure in men around 20 years of age. These results indicate the importance of evaluation and reduction of intra-abdominal fat to prevent hypertension.

Androgen receptor CAG repeat polymorphism and hypothalamic-pituitary-gonadal function in Filipino young adult males

OBJECTIVES

Testosterone (T), the primary androgenic hormone in males, is stimulated through pulsatile secretion of LH and regulated through negative feedback inhibition at the hypothalamus and pituitary. The hypothalamic-pituitary-gonadal (HPG) axis also controls sperm production through the secretion of follicle-stimulating hormone (FSH). Negative feedback in the HPG axis is achieved in part through the binding of T to the androgen receptor (AR), which contains a highly variable trinucleotide repeat polymorphism (AR-CAGn). The number of repeats in the AR-CAGn inversely correlates with transcriptional activity of the AR. Thus, we predicted longer AR-CAGn to be associated with higher T, LH, and FSH levels.

METHODS

We examined the relationship between AR-CAGn and total plasma T, LH, and FSH, as well as "bioavailable" morning (AM-T) and evening (PM-T) testosterone in 722 young (21.5 ± 0.5 years) Filipino males.

RESULTS

There was no relationship between AR-CAGn and total T, AM-T, or LH (P > .25 for all). We did observe a marginally non-significant (P = .066) correlation between AR-CAGn and PM-T in the predicted direction, and a negative correlation between AR-CAGn and FSH (P = .005).

CONCLUSIONS

Our results both support and differ from previous findings in this area, and study parameters that differ between our study and others, such as participant age, sample time, and the role of other hormones should be considered when interpreting our findings. While our data point to a modest effect of AR-CAGn on HPG regulation at best, the AR-CAGn may still affect somatic traits by regulating androgenic activity at peripheral tissues.

Comparison of visceral and body fat indices and anthropometric measures in relation to untreated hypertension by age and gender among Chinese

BACKGROUND

The aim of the study was to compare the efficiency of bioelectrical indices (percentage body fat, PBF; visceral fat index, VFI) and various anthropometric measures (body mass index, BMI; waist circumference, WC; waist-to-height ratio, WHtR) on determining hypertension in Chinese.

METHODS

We conducted the community-based cross-sectional survey during August of 2013 to August of 2015 in 66 sample sites selected by multistage random sampling method from Henan province. 14,364 residents were included in the study.

RESULTS

In both genders, VFI and PBF tended to rise with age. However, for each age-specific group, men consistently had significantly greater VFI than women (all P<0.0001) and women had considerably higher PBF (all P<0.0001). The odds ratios and area under the ROC curves (AUCs) for hypertension associated with adiposity indices decreased with age. In younger (15~34year) men and women, VFI had the highest crude (2.43-7.95) and adjusted (2.40-11.63) odds ratio for hypertension. The AUCs for PBF, VFI and WHtR were significantly larger than those for BMI and WC (all P<0.01). Whereas no statistically significant difference were found in AUCs among PBF, VFI and WHtR (all P>0.10). Additionally, VFI and PBF yielded the greatest Youden index in identifying hypertension in men (0.27) and women (0.34), respectively. Optimal cutoffs for VFI/PBF were 11.70/24.45 and 7.55/33.65 in men and women, respectively.

CONCLUSIONS

VFI and PBF could be better candidates for identifying hypertension in men and women, respectively. Adolescents and young adults should be highlighted in preventing hypertension by control of excess body and visceral fat.

Association of visceral and total body fat with hypertension and prehypertension in a middle-aged Chinese population

OBJECTIVE

This article investigates the relative effects of percentage body fat (PBF) and visceral fat index (VFI) on the prevalence of hypertension and prehypertension, and evaluates if excess visceral deposition of body fat increased the risk of hypertension or prehypertension.

METHODS

A general population-based sample of men (n = 5297) and women (n = 6232), aged 35-64 years, was studied. Based on blood pressure (BP) levels, normotensive, prehypertensive, and hypertensive study participants were identified. Multivariate linear regression models with SBP or DBP as a dependent variable and multivariate ordinal logistic regression models with BP categories as a dependent variable were performed.

RESULTS

In the normotensive, prehypertensive, and hypertensive participants, the mean (standard deviation) PBF was 27.83 (6.85), 28.91 (6.65), and 30.2 (6.73), respectively, whereas VFI was 6.97 (3.78), 8.89 (4.35), and 10.75 (5.05), respectively. After adjusting for age, smoking, alcohol consumption, education, regions (north or south), areas (urban or rural), diabetes, and family history, PBF and VFI (in separate models) showed a strong positive association with hypertension or prehypertension (P < 0.0001). However, when both PBF and VFI were adjusted for in the same multivariate model, VFI but not PBF remained positively associated with hypertension and prehypertension for both genders (P < 0.0001). A similar positive association was reported with the VFI/PBF ratio (P < 0.0001).

CONCLUSION

As excess visceral body fat is strongly associated with higher risk of hypertension and prehypertension, measurements of VFI or VFI/PBF ratio, in addition to PBF, will provide a better understanding of adiposity-related risks for hypertension and prehypertension.

Androgen receptor (AR) gene CAG trinucleotide repeat length associated with body composition measures in non-syndromic obese, non-obese and Prader-Willi syndrome individuals

PURPOSE

Total body mass impacts reproductive health and infertility which has increased in the United States with rising rates of obesity. Overlapping genetic and environmental factors contribute to obesity and infertility including the androgen receptor (AR), a steroid hormone-activated transcription factor that is key in regulating androgen activity and sensitivity to sex hormones, weight and body composition in both males and females. The AR gene which is X-linked contains a polymorphic CAG trinucleotide repeat which varies in length and inversely correlated with gene expression.

METHODS

We examined the AR gene CAG repeat length and measures of weight and body mass index (BMI) in 27 non-syndromic obese and 33 lean controls and for the first time compared with 28 individuals with Prader-Willi syndrome (PWS), a rare obesity-related genetic disorder with natural sex hormone deficits to examine the effects of AR gene CAG repeat length on androgen-mediated response and obesity-related factors relevant to human infertility and reproduction.

RESULTS

Mean CAG repeat length in base pairs (278 ± 7.9) did not significantly differ by subject group (F = 2.6, p = 0.08) but was strongly positively correlated with height standard deviation (SD) among males (r = 0.31, p < 0.05), mainly lean and obese, but not PWS (r = 0.02, p = 0.94). A negative correlation was observed for weight SD among females (r = -0.29, p < 0.04) when grouped together.

CONCLUSIONS

The results were consistent with an androgen-mediated effect on height and weight negligible in PWS and supporting the role of sex hormones and AR gene interaction in obesity and infertility, both cardinal features of PWS. CAG repeat length of the AR gene is a marker for increased androgen sensitivity with shorter lengths predicting smaller stature in non-PWS adult males possibly due to accelerating fusion of bone growth plates and reducing the growth phase. Increased androgen effects from shorter CAG repeat lengths in non-PWS females could impact pregnancy-related weight gain and pregnancy outcomes.

Genetics of cardiovascular disease: Importance of sex and ethnicity

Sex differences in incidence and prevalence of and morbidity and mortality from cardiovascular disease are well documented. However, many studies examining the genetic basis for cardiovascular disease fail to consider sex as a variable in the study design, in part, because there is an inherent difficulty in studying the contribution of the sex chromosomes in women due to X chromosome inactivation. This paper will provide general background on the X and Y chromosomes (including gene content, the pseudoautosomal regions, and X chromosome inactivation), discuss how sex chromosomes have been ignored in Genome-wide Association Studies (GWAS) of cardiovascular diseases, and discuss genetics influencing development of cardiovascular risk factors and atherosclerosis with particular attention to carotid intima-medial thickness, and coronary arterial calcification based on sex-specific studies. In addition, a brief discussion of how ethnicity and hormonal status act as confounding variables in sex-based analysis will be considered along with methods for statistical analysis to account for sex in cardiovascular disease.

Saguenay Youth Study: a multi-generational approach to studying virtual trajectories of the brain and cardio-metabolic health

This paper provides an overview of the Saguenay Youth Study (SYS) and its parental arm. The overarching goal of this effort is to develop trans-generational models of developmental cascades contributing to the emergence of common chronic disorders, such as depression, addictions, dementia and cardio-metabolic diseases. Over the past 10 years, we have acquired detailed brain and cardio-metabolic phenotypes, and genome-wide genotypes, in 1029 adolescents recruited in a population with a known genetic founder effect. At present, we are extending this dataset to acquire comparable phenotypes and genotypes in the biological parents of these individuals. After providing conceptual background for this work (transactions across time, systems and organs), we describe briefly the tools employed in the adolescent arm of this cohort and highlight some of the initial accomplishments. We then outline in detail the phenotyping protocol used to acquire comparable data in the parents.

Influence of CAG Repeat Polymorphism on the Targets of Testosterone Action

In the last decade, ample evidence has demonstrated the growing importance of androgen receptor (AR) CAG repeat polymorphism in andrology. This genetic parameter is able to condition the peripheral effects of testosterone and therefore to influence male sexual function and fertility, cardiovascular risk, body composition, bone metabolism, the risk of prostate and testicular cancer, the psychiatric status, and the onset of neurodegenerative disorders. In this review, we extensively discuss the literature data and identify a role for AR CAG repeat polymorphism in conditioning the systemic testosterone effects. In particular, our main purpose was to provide an updated text able to shed light on the many and often contradictory findings reporting an influence of CAG repeat polymorphism on the targets of testosterone action.

The gonadal function in obese adolescents: review

This review deals with the relationship between obesity in male adolescents and gonadal function. The article is structured in two main paragraphs; the first one is about population studies that have assessed puberty timing and its mode of onset in relation with body weight to evaluate if and how the latter can influence the gonadal function in this phase of life. These studies analyze issues such as increased BMI and early onset of male puberty, gender differences, secular trend toward early onset of puberty in males, effects of a different body composition on male puberty and consequences of a different stage of childhood obesity on the onset of male puberty. The second paragraph examines the possible mechanisms through which, obesity may alter the timing of puberty in young males, including the role of SHBG, leptin, insulin resistance, ghrelin, GH-IGF-1 axis, AR polymorphisms, primary testicular dysfunction, retinol binding protein 4 (RBP-4) and liver function abnormalities. However, despite the numerous studies in the literature, the etiology of gonadal disfunction in obese adolescents on puberty remains uncertain.

Prevalence of high blood pressure in 122,053 adolescents: a systematic review and meta-regression

Several studies have reported high prevalence of risk factors for cardiovascular disease in adolescents. To perform: i) systematically review the literature on the prevalence of high blood pressure (HBP) in adolescents; ii) analyze the possible methodological factors associated with HBP; and iii) compare the prevalence between developed and developing countries. We revised 10 electronic databases up to August 11, 2013. Only original articles using international diagnosis of HBP were considered. The pooled prevalence's of HBP were estimated by random effects. Meta-regression analysis was used to identify the sources of heterogeneity across studies. Fifty-five studies met the inclusion criteria and total of 122,053 adolescents included. The pooled-prevalence of HBP was 11.2%, 13% for boys, and 9.6% for girls (P < 0.01). Method of measurement of BP and year in which the survey was conducted were associated with heterogeneity in the estimates of HBP among boys. The data indicate that HBP is higher among boys than girls, and that the method of measurement plays an important role in the overall heterogeneity of HBP value distributions, particularly in boys.

Autonomic nervous system dysregulation in pediatric hypertension

Historically, primary hypertension (HTN) has been prevalent typically in adults. Recent data however, suggests an increasing number of children diagnosed with primary HTN, mainly in the setting of obesity. One of the factors considered in the etiology of HTN is the autonomous nervous system, namely its dysregulation. In the past, the sympathetic nervous system (SNS) was regarded as a system engaged mostly in buffering major acute changes in blood pressure (BP), in response to physical and emotional stressors. Recent evidence suggests that the SNS plays a much broader role in the regulation of BP, including the development and maintenance of sustained HTN by a chronically elevated central sympathetic tone in adults and children with central/visceral obesity. Consequently, attempts have been made to reduce the SNS hyperactivity, in order to intervene early in the course of the disease and prevent HTN-related complications later in life.

Potential biases in the classification, analysis and interpretations in cross-sectional study: commentaries - surrounding the article "resting heart rate: its correlations and potential for screening metabolic dysfunctions in adolescents"

BACKGROUND

Resting heart rate reflects sympathetic nerve activity. A significant association between resting heart rate (HR) and all causes of cardiovascular mortality has been reported by some epidemiologic studies. Despite suggestive evidence, resting heart rate (RHR) has not been formally explored as a prognostic factor and potential therapeutic outcome and, therefore, is not generally accepted in adolescents.

DISCUSSION

The core of the debate is the methodological aspects used in "Resting heart rate: its correlations and potential for screening metabolic dysfunctions in adolescents"; the points are: cutoff used for cluster RHR, two different statistical models used to analyze the same set of variables, one for continuous data, and another for categorical data; interpretation of p-value < 0.05, sampling process involving two random stages, analysis of design effect and the parameters of screening tests.

SUMMARY

Aspects that must be taken into account for evaluation of a screening test to measure the potential for discrimination for a common variable (population with outcome vs. no outcome population), the main indicators are: sensitivity, specificity, accuracy, positive predictive value and negative predictive value. The measures of argumentation equality (CI) or difference (p-valor) are important to validate these indicators but do not indicate quality of screening.

Vitamins and iron blood biomarkers are associated with blood pressure levels in European adolescents. The HELENA study

OBJECTIVES

Previous research showed that low concentration of biomarkers in the blood during adolescence (i.e., iron status; retinol; and vitamins B6, B12, C, and D) may be involved in the early stages of development of many chronic diseases, such as hypertension. The aim was to evaluate if iron biomarkers and vitamins in the blood are associated with blood pressure in European adolescents.

METHODS

Participants from the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study (N = 1089; 12.5-17.5 y; 580 girls) were selected by complex sampling. Multilevel linear regression models examined the associations between iron biomarkers and vitamins in the blood and blood pressure; the analyses were stratified by sex and adjusted for contextual and individual potential confounders.

RESULTS

A positive association was found in girls between RBC folate concentration and systolic blood pressure (SBP) (β = 3.19; 95% confidence interval [CI], 0.61-5.77), although no association between the vitamin serum biomarkers concentrations and diastolic blood pressure (DBP) was found. In boys, retinol was positively associated with DBP (β = 3.84; 95% CI, 0.51-7.17) and vitamin B6 was positively associated with SBP (β = 3.82; 95% CI, 1.46-6.18). In contrast, holotranscobalamin was inversely associated with SBP (β = -3.74; 95% CI, -7.28 to -0.21).

CONCLUSIONS

Levels of RBC folate and vitamin B6 in blood may affect BP in adolescents. In this context, programs aimed at avoiding high BP levels should promote healthy eating behavior by focusing on the promotion of vegetable proteins and foods rich in vitamin B12 (i.e., white meat and eggs), which may help to achieve BP blood control in adolescents.

Urinary phthalates are associated with higher blood pressure in childhood

OBJECTIVE

To examine associations of urinary phthalate levels with blood pressure (BP) and serum triglyceride and lipoprotein levels in children.

STUDY DESIGN

We performed a cross-sectional analysis of a subsample of US children aged 6-19 years who participated in the National Health and Nutrition Examination Survey between 2003 and 2008. We quantified exposure to 3 families of phthalates--low molecular weight, high molecular weight and di-2-ethylhexylphthalate (DEHP)--based on molar concentration of urinary metabolites. We assessed descriptive, bivariate, and multivariate associations with BP and lipid levels.

RESULTS

Controlling for an array of sociodemographic and behavioral factors, as well as diet and body mass index, levels of metabolites of DEHP, a phthalate commonly found in processed foods, were associated with higher age-, sex-, and height-standardized BP. For each log unit (roughly 3-fold) increase in DEHP metabolites, a 0.041 SD unit increase in systolic BP z-score was identified (P = .047). Metabolites of low molecular weight phthalates commonly found in cosmetics and personal care products were not associated with BP. Phthalate metabolites were not associated with triglyceride levels, high-density lipoprotein level, or prehypertension.

CONCLUSIONS

Dietary phthalate exposure is associated with higher systolic BP in children and adolescents. Further work is needed to confirm these associations, as well as to evaluate opportunities for intervention.

Visceral fat is associated with lower executive functioning in adolescents

BACKGROUND

Obesity, a major risk factor for cardiometabolic disease, is associated with lower cognitive performance from childhood to senescence, especially on tasks of executive function. In the cardiovascular domain, fat stored viscerally rather than elsewhere in the body carries particularly high risk. It is unknown whether this is also true in case of obesity-cognition relationships. The aim of this study was to assess the cross-sectional relationship between visceral fat (VF) and cognitive performance in a community sample of healthy adolescents.

METHODS

In a community-based sample of 983 adolescents (12-18 years old, 480 males), VF was quantified using magnetic resonance imaging, total body fat was measured using a multifrequency bioimpedance, and cognitive performance was assessed using a battery of cognitive tests measuring executive function and memory.

RESULTS

We found that larger volumes of VF were associated with lower performance on six measures of executive function (P=0.0001-0.02). We also found that the association of VF with executive function was moderated by sex for a subset of measures, such that relationship was present mainly in female subjects and not in male subjects (sex-by-VF interaction: P=0.001-0.04). These relationships were independent of the quantity of total body fat and a number of potential confounders, including age, puberty stage and household income.

CONCLUSIONS

Our results suggest that the adverse association between obesity and executive function may be attributed to fat stored viscerally and not to fat stored elsewhere in the body. They also suggest that female subjects compared with male subjects may be more sensitive to the potentially detrimental effects of VF on cognition.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Androgen receptor (CAG)n polymorphism and androgen levels in women with systemic lupus erythematosus and healthy controls

Systemic lupus erythematosus (SLE) is an autoimmune disorder that affects mainly females. Therefore, interrelations between the reproductive and immune system have been assumed. Considering the complex influence of hormones and receptors, we aimed to investigate the influence of androgens and androgen receptor (AR) polymorphism in women with SLE. One hundred and sixteen patients and 44 healthy women were investigated. Testosterone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone-sulphate (DHEAS) concentrations and AR (CAG)n polymorphism were determined. SLE patients had significantly lower levels of total and free testosterone and DHEAS in comparison with the controls. No differences in the CAG repeat length between the groups were established. Women with two alleles carrying more than 22 CAG repeats had significantly higher levels of SHBG (101.51 ± 61.81 vs. 69.22 ± 45.93 nmol/l, p = 0.015) and DHEAS (3.11 ± 2.65 vs. 2.11 ± 3.06 μmol/l, p = 0.007) and a tendency to higher testosterone concentrations (2.35 ± 2.10 vs. 1.71 ± 1.70 nmol/l, p = 0.056) in comparison with other women. The CAG repeat length in the relatively longer (CAG)n allele was inversely related to the Systemic Lupus International Collaborating Clinics/ACR index (r = -0.258, p = 0.009). In conclusion, the androgen receptor (CAG)n polymorphism is not related to the development of SLE, but it could modulate the severity of the lupus chronic damages as well as the androgen levels in women.

Androgen signaling promotes translation of TMEFF2 in prostate cancer cells via phosphorylation of the α subunit of the translation initiation factor 2

The type I transmembrane protein with epidermal growth factor and two follistatin motifs 2 (TMEFF2), is expressed mainly in brain and prostate. Expression of TMEFF2 is deregulated in prostate cancer, suggesting a role in this disease, but the molecular mechanism(s) involved in this effect are not clear. Although androgens promote tmeff2 transcription, androgen delivery to castrated animals carrying CWR22 xenografts increases TMEFF2 protein levels in the absence of mRNA changes, suggesting that TMEFF2 may also be post-transcriptionally regulated. Here we show that translation of TMEFF2 is regulated by androgens. Addition of physiological concentrations of dihydrotestosterone (DHT) to prostate cancer cell lines increases translation of endogenous TMEFF2 or transfected TMEFF2-Luciferase fusions, and this effect requires the presence of upstream open reading frames (uORFs) in the 5′-untranslated region (5′-UTR) of TMEFF2. Using chemical and siRNA inhibition of the androgen receptor (AR), we show that the androgen effect on TMEFF2 translation is mediated by the AR. Importantly, DHT also promotes phosphorylation of the α subunit of the translation initiation factor 2 (eIF2α) in an AR-dependent manner, paralleling the effect on TMEFF2 translation. Moreover, endoplasmic reticulum (ER) stress conditions, which promote eIF2α phosphorylation, also stimulate TMEFF2 translation. These results indicate that androgen signaling promotes eIF2α phosphorylation and subsequent translation of TMEFF2 via a mechanism that requires uORFs in the 5′-UTR of TMEFF2.

Use of MRI and CT for fat imaging in children and youth: what have we learned about obesity, fat distribution and metabolic disease risk?

Childhood obesity is a matter of great concern for public health. Efforts have been made to understand its impact on health through advanced imaging techniques. An increasing number of studies focus on fat distribution and its associations with metabolic risk, in interaction with genetics, environment and ethnicity, in children. The present review is a qualitative synthesis of the existing literature on visceral and subcutaneous abdominal, intrahepatic and intramuscular fat. Our search revealed 80 original articles. Abdominal as well as ectopic fat depots are prevalent already in childhood and contribute to abnormal metabolic parameters, starting early in life. Visceral, hepatic and intramuscular fat seem to be interrelated but their patterns as well as their independent contribution on metabolic risk are not clear. Some ethnic-specific characteristics are also prevalent. These results encourage further research in childhood obesity by using imaging techniques such as magnetic resonance imaging and computed tomography. These imaging methods can provide a better understanding of fat distribution and its relationships with metabolic risk, compared to less detailed fat and obesity assessment. However, studies on bigger samples and with a prospective character are warranted.

Androgen receptor polyglutamine repeat number: models of selection and disease susceptibility

Variation in polyglutamine repeat number in the androgen receptor (AR CAGn) is negatively correlated with the transcription of androgen-responsive genes and is associated with susceptibility to an extensive list of human disease. Only a small portion of the heritability for many of these diseases is explained by conventional SNP-based genome-wide association studies, and the forces shaping AR CAGn among humans remains largely unexplored. Here, we propose evolutionary models for understanding selection at the AR CAG locus, namely balancing selection, sexual conflict, accumulation-selection, and antagonistic pleiotropy. We evaluate these models by examining AR CAGn-linked susceptibility to eight extensively studied diseases representing the diverse physiological roles of androgens, and consider the costs of these diseases by their frequency and fitness effects. Five diseases could contribute to the distribution of AR CAGn observed among contemporary human populations. With support for disease susceptibilities associated with long and short AR CAGn, balancing selection provides a useful model for studying selection at this locus. Gender-specific differences AR CAGn health effects also support this locus as a candidate for sexual conflict over repeat number. Accompanied by the accumulation of AR CAGn in humans, these models help explain the distribution of repeat number in contemporary human populations.

Sex differences in the contributions of visceral and total body fat to blood pressure in adolescence

Excess body fat deposited viscerally rather than elsewhere in the body is associated with higher risk for hypertension; this relationship is stronger in men than in women. Here we investigated whether similar sex dimorphism exists already in adolescence. A population-based sample of adolescent boys (n=237) and girls (n=262), age 12 to 18 years, was studied. Total body fat (TBF) was assessed with multifrequency bioelectrical impedance, and visceral fat (VF) was quantified with MRI. Blood pressure (BP) was measured beat by beat during an hour-long protocol, including supine, standing, sitting, mental stress, and poststress sections. Multivariate mixed-model analysis was used to assess the relative contributions of TBF and VF to BP during these sections. In boys, BP was strongly positively associated with VF (P<0.0001), whereas it was less strongly and negatively associated with TBF (P=0.004); these relationships did not substantially vary during the protocol. In contrast, in girls, BP was strongly positively associated with TBF (P=0.0006), whereas it was not associated with VF (P=0.08); the relationship with TBF varied during the protocol and was most apparent during mental stress (TBF*section interaction: P=0.002). Furthermore, when waist circumference was included in multivariate models instead of VF, it was not associated with BP in either sex; this indicates that waist circumference may not be an appropriate surrogate for VF. Thus, in adolescence, adiposity-related BP elevation is driven mainly by visceral fat in males and by fat deposited elsewhere in females. This dimorphism suggests sex-specific mechanisms of obesity-induced hypertension and the need for sex-specific criteria of its prevention.

Blood Pressure Control at Rest and during Exercise in Obese Children and Adults

The hemodynamic responses to exercise have been studied to a great extent over the past decades, and an exaggerated blood pressure response during an acute exercise bout has been considered as an indicator of cardiovascular risk. Obesity is a major factor influencing the blood pressure response to exercise since evidence indicates that the arterial pressure response to exercise is exacerbated in obese compared with lean adults. Signs of augmented responses (such as an exaggerated blood pressure response) to physical exertion appear early in life (from the prepubertal years) in obese individuals. Understanding the mechanisms that drive the altered hemodynamic responses during exercise in obese individuals and prevent the progression to hypertension is vitally important. This paper focuses on the evidence linking obesity with alterations of the autonomic nervous system and discusses the potential mechanisms and consequences of the altered sympathetic nervous system behavior in obese individuals at rest and during exercise. Furthermore, this paper presents the alterations in the reflex regulatory mechanisms ("exercise pressor reflex" and baroreflex) in obese children and adults and addresses the effects of training on obesity-related disturbances.

What can allostasis tell us about anabolic-androgenic steroid addiction?

Anabolic-androgenic steroids (AASs) are synthetic hormones used by individuals who want to look better or perform better in athletics and at the gym. Their use raises an interesting paradox in which drug use is associated with a number of health benefits, but also the possibility of negative health consequences. Existing models of AAS addiction follow the traditional framework of drug abuse and dependence, which suggest that harmful use occurs as a result of the drug's ability to hijack the motivation-reward system. However, AASs, unlike typical drugs of abuse, are not used for acute intoxication effects or euphoria. Rather, AASs are used to affect the body through changes to the musculoskeletal system and the hypothalamic-pituitary-gonadal axis as opposed to stimulating the reward system. We offer an allostatic model of AAS addiction to resolve this inconsistency between traditional drug addiction and AAS addiction. This allostatic framework provides a way to (a) incorporate exercise into AAS misuse, (b) identify where AAS use transitions from recreational use into a drug problem, and (c) describe individual differences in vulnerability or resilience to AASs. Implications for this model of AAS addiction are discussed.

Sex-based differences in vascular function

Cardiovascular disease is the leading cause of morbidity and mortality for both men and women in the USA. However, there are differences between the sexes in age-dependent onset, severity, symptoms and outcomes. Basic research into the causes of sex-dependent differences in cardiovascular disease is ongoing and includes investigation into genetic variation in expression and distribution of receptors for the sex steroids; specificity of natural and synthetic ligands that activate the sex steroid receptors; and intracellular mechanisms that are activated by the receptors in all components of the vessel wall and blood elements, which integrate to regulate vascular tone, vascular repair and remodeling in health and disease. In this era of personalized medicine, basic research into mechanisms of sex differences in vascular function will result in improved prevention, detection and treatment of cardiovascular disease in both men and women.

Altered hemodynamic regulation and reflex control during exercise and recovery in obese boys

The aims of the present study were to assess in obese and lean boys 1) the hemodynamic responses and baroreflex sensitivity (BRS) to isometric handgrip exercise (HG) and recovery and 2) the muscle metaboreflex-induced blood pressure response and the variables that determine this response. Twenty-seven boys (14 obese and 13 lean boys, body mass index: 29.2 ± 0.9 vs. 18.9 ± 0.3 kg/m(2), respectively) participated. The testing protocol involved 3 min of baseline, 3 min of HG (30% maximum voluntary contraction), 3 min of circulatory occlusion, and 3 min of recovery. The same protocol was repeated without occlusion. At baseline, no differences were detected between groups in beat-to-beat arterial pressure (AP), heart rate (HR), and BRS; however, obese boys had higher stroke volume and lower total peripheral resistance than lean boys (P < 0.05). During HG, lean boys exhibited higher HR and lower BRS compared with their obese counterparts. In lean boys, BRS decreased during HG compared with baseline, whereas in obese boys, it was not significantly modified. In lean boys, TPR was elevated during HG and declined after exercise, whereas in obese boys, TPR did not significantly decrease after exercise cessation. In the postexercise period, BRS in lean boys returned to baseline, whereas an overshoot was observed in obese boys. Postexercise BRS was correlated with body mass index (R = 0.56, P < 0.05). Although the metaboreflex-induced increase in AP was similar between obese and lean children, it was achieved via different mechanisms: in lean children, total peripheral resistance was the main contributor to AP maintenance during the metaboreflex, whereas in obese children, stroke volume significantly contributed to AP maintenance during the metaboreflex. In conclusion, obese normotensive children demonstrated altered cardiovascular hemodynamics and reflex control during exercise and recovery.