1.
Ethnic and sex differences in body fat and visceral and subcutaneous adiposity in children and adolescents.
Staiano, AE, Katzmarzyk, PT
International journal of obesity (2005). 2012;(10):1261-9
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Abstract
Body fat and the specific depot where adipose tissue (AT) is stored can contribute to cardiometabolic health risks in children and adolescents. Imaging procedures including magnetic resonance imaging and computed tomography allow for the exploration of individual and group differences in pediatric adiposity. This review examines the variation in pediatric total body fat (TBF), visceral AT (VAT) and subcutaneous AT (SAT) due to age, sex, maturational status and ethnicity. TBF, VAT and SAT typically increase as a child ages, though different trends emerge. Girls tend to accumulate more TBF and SAT during and after puberty, depositing fat preferentially in the gynoid and extremity regions. In contrast, pubertal and postpubertal boys tend to deposit more fat in the abdominal region, particularly in the VAT depot. Sexual maturation significantly influences TBF, VAT and SAT. Ethnic differences in TBF are mixed. VAT tends to be higher in white and Hispanic youth, whereas SAT is typically higher in African American youth. Asian youth typically have less gynoid fat but more VAT than whites. Obesity per se may attenuate sex and ethnic differences. Particular health risks are associated with high amounts of TBF, VAT and SAT, including insulin resistance, hepatic steatosis, metabolic syndrome and hypertension. These risks are affected by genetic, biological and lifestyle factors including physical activity, nutrition and stress. Synthesizing evidence is difficult as there is no consistent methodology or definition to estimate and define depot-specific adiposity, and many analyses compare SAT and VAT without controlling for TBF. Future research should include longitudinal examinations of adiposity changes over time in representative samples of youth to make generalizations to the entire pediatric population and examine variation in organ-specific body fat.
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Local adipose tissue renin-angiotensin system.
Cassis, LA, Police, SB, Yiannikouris, F, Thatcher, SE
Current hypertension reports. 2008;(2):93-8
Abstract
A local renin-angiotensin system (RAS) has been proposed in adipocytes. Adipocytes are a suggested source of components of the RAS, with regulation of their production related to obesity-hypertension. Both angiotensin type 1 and 2 receptors have been localized to adipocytes. Angiotensin II has been demonstrated to regulate adipocyte growth and differentiation, lipid metabolism, and expression and release of adipokines and RAS components, and to promote oxidative stress. Differences in regional expression of RAS components in visceral versus subcutaneous adipose tissue have been suggested as a link between abdominal obesity and cardiovascular disease. Finally, several studies support antihypertensive efficacy of RAS blockade in patients with type 2 diabetes and obesity. Future studies should address the role of adipocyte-specific deficiency of RAS components to definitively determine the relevance of the adipose RAS to normal physiology and to the development of hypertension.