Association of Ang-(1-7) and des-Arg9BK as new biomarkers of obesity and cardiometabolic risk factors in adolescents.

Children with obesity have a high risk of developing cardiovascular disease and hypertension, which is associated with the renin-angiotensin system (RAS) activation and kallikrein-kinin system (KKS) inactivation. Although recent studies have identified several peptide-based biomarkers for obesity, circulating peptides from the RAS and KKS in adolescents with obesity have not been described. The aim of this study was to examine circulating levels of RAS and KKS peptides in adolescents with obesity to investigate the turnover of these peptides and their relationship to metabolic disorders resulting from weight gain. The subjects (n = 104) were divided into normal weight (NW), overweight (OW), obese (OB), and morbidly obese (MO) groups. Anthropometric profiles were created by measuring height, weight, blood pressure, and skinfolds. Plasma levels of Ang I, II, (1-7), BK, and des-Arg9BK were quantified by high-performance liquid chromatography. The levels were as follows: Ang-(1-7)-MO 58.3 ± 50, OB 223.2 ± 150, OW 318.6 ± 190, NW 479.1 ± 160 pmol/mL, and Bradykinin (BK)-MO 367.6 ± 103, OB 253.8 ± 130, OW 484 ± 279, NW 874.9 ± 385 pmol/mL. Ang-(1-7) correlated inversely with weight, body mass index, leptin, diastolic blood pressure, and systolic blood pressure. BK and Ang-(1-7) levels correlated inversely with skinfolds, waist-hip ratio (WHR), leptin, and arm circumference. BK levels correlated with adiponectin and Ang-(1-7) levels. Plasma Ang I levels were higher in the MO and OB groups than in the NW group, but plasma Ang II levels were similar in all groups. We suggest that Ang-(1-7) and des-Arg9BK metabolites are novel biomarkers of childhood obesity that are important for determining treatment strategies.

Effect of calcium intake, tennis playing, and body composition on bone-mineral density of Brazilian male adolescents.

In this prospective, cross-sectional study male adolescent tennis players (44) and nonathletic controls (32) were evaluated to determine the effects of physical activity, dietary nutrient intakes, sexual maturation, and body composition on bone-mineral density (BMD). Dietary nutrient intakes and physical activity expenditure were estimated by 4-d diaries. Total body composition, bone-mineral content (BMC), and BMD (L1-L4, femur, and nondominant forearm) were assessed by dual-energy X-ray absorptiometry. Tennis players had significantly greater lean body mass (mean [SEM] 50.6 [1.6] kg vs. 45.1 [1.7] kg, p = .022), trochanter BMD (1.0 [0.02] g/cm2 vs. 0.9 [0.03] g/cm2, p = .032), and dominant forearm BMC (173.7 [7.4] g vs. 146.5 [9.3] g) but lower BMD in the nondominant forearm (0.7 [0.02] g/cm2 vs. 0.8 [0.03] g/cm2, p = .028). Daily average calcium intake was below the recommendation in both groups. No correlation was found between BMD and calcium intake and exercise. Lean body mass was the best predictor of BMD and BMC for both tennis players and controls (R2 = .825, .628, and .693 for L1-L4, total femur, and nondominant forearm, respectively). Based on these results the authors conclude that lean body mass is the best predictor of BMD and BMC for both tennis players and others. Tennis exerts a site-specific effect, and training should focus on ways minimize this effect. Although calcium intake showed no effect on BMD, nutrition education for young athletes should focus on promoting a balanced diet, providing energy and nutrients in adequate amounts.