Central adiposity and hemodynamic functioning at rest and during stress in adolescents.

OBJECTIVE: To examine the impact of central adiposity upon hemodynamic functioning at rest and during stress in adolescents. DESIGN: Cross-sectional, correlational study. SUBJECTS: 46 White and 49 Black normotensive adolescents with family histories of essential hypertension. MEASUREMENTS: Systolic and diastolic blood pressure (SBP, DBP), cardiac output and total peripheral resistance responses were assessed at rest, during postural change, video game challenge and forehead cold stimulation. Specific lower and higher waist-to-hip ratio (WHR) tertiles were created for each gender and then integrated for analyses. This resulted in a lower WHR tertile of 11 Whites and 21 Blacks and an upper WHR tertile of 15 Whites and 17 Blacks. RESULTS: No differences in age, gender or ethnicity proportions were found between tertile groups (all P > 0.21). The upper WHR group showed greater body weight, waist and hip circumferences, body mass index (BMI), triceps skinfold and body surface area (all P < 0.001). Controlling for peripheral (that is, triceps skinfold) and overall (that is, BMI) adiposity, the upper WHR group exhibited greater SBP (that is, peak response minus mean pre-stressor level) to all three stressors and greater DBP reactivity to postural change and cold pressor (all P < 0.05). CONCLUSION: Central adiposity appears to adversely influence hemodynamic functioning during adolescence. Underlying mechanisms responsible for these associations require exploration.

Antibiotic resistance of bacterial litter isolates.

Use of antibiotics in subtherapeutic doses as growth-promoting feed additives for animal production is widespread in the U.S. and throughout the world. Previous studies by our research group concluded that size fractionation of poultry (broiler) litter followed by storage facilitated reutilization of litter as a soil amendment or bedding supplement. However, litter microbial contamination, including antibiotic-resistant populations, and accumulation of metals and other elements may limit litter reutilization. Litter from four broiler houses was separated into a fine fraction for use as a soil amendment, and a coarse fraction for reutilization as a bedding supplement in growing subsequent flocks of broilers. Fractions and whole litter were stored in indoor piles simulating farm storage conditions for 4 mo with periodic analysis for metals, other elements, and culturable bacteria (including total and fecal coliform, Aeromonas hydrophila, Pseudomonas aeruginosa, Yersinia enterocolitica, and Campylobacter jejuni). Representative bacterial isolates were tested for their sensitivity to 12 common antibiotics (ampicillin, bacitracin, cephalothin, erythromycin, gentamicin, kanamycin, nalidixic acid, neomycin, penicillin, streptomycin, sulfisoxazole, and tetracycline) using the Kirby-Bauer technique. Pathogens and indicator bacteria tested were found to be resistant to multiple antibiotics. Data suggest that microbial contamination of litter should be reduced or eliminated prior to reutilization to minimize environmental health risks related to transfer of antibiotic-resistant bacteria to humans or other animals.