Association of PPARG2 Pro12Ala variant with larger body mass index in Mestizo and Amerindian populations of Mexico.

Previous studies have sought to associate the Pro12Ala variant of the peroxisome proliferator-activated receptor gamma2 (PPARG2) gene with type 2 diabetes, insulin resistance, and obesity, with controversial results. We have determined the Pro12Ala variant frequency in 370 nondiabetic Mexican Mestizo subjects and in five Mexican Amerindian groups and have investigated its possible association with lipid metabolism, insulin serum levels, and obesity in three of these populations. Two independent case-control studies were conducted in 239 nondiabetic individuals: 135 case subjects (BMI > or = 25 kg/m2) and 104 control subjects (BMI < 25 kg/m2). The PPARG2 Ala12 allele frequency was higher in most Amerindian populations (0.17 in Yaquis, 0.16 in Mazahuas, 0.16 in Mayans, and 0.20 in Triquis) than in Asians, African Americans, and Caucasians. The Pro12Ala and Ala12Ala (X12Ala) genotypes were significantly associated with greater BMI in Mexican Mestizos and in two Amerindian groups. X12Ala individuals had a higher risk of overweight or obesity than noncarriers in Mestizos (OR = 3.67; 95% CI, 1.42-9.48; p = 0.007) and in Yaquis plus Mazahuas (OR = 3.21; 95% CI, 1.27-8.11; p = 0.013). Our results provide further support of the association between the PPARG2 Ala12 allele and risk of overweight or obesity in Mestizos and two Amerindian populations from Mexico.

Skeletal muscle mitochondria in the elderly: effects of physical fitness and exercise training.

Context: Sarcopenia is thought to be associated with mitochondrial (M) loss. It is unclear whether the decrease in M content is consequent to aging per se or to decreased physical activity. Objectives: To examine the influence of fitness on M content and function, and to assess whether exercise could improve M function in older adults. Design and subjects: Three distinct studies were conducted: 1) a cross-sectional observation comparing M content and fitness in a large heterogeneous cohort of older adults; 2) a case-control study comparing chronically endurance-trained older adults (A) and sedentary (S) subjects matched for age and gender; 3) a 4-month exercise intervention in S. Setting: University-based clinical research center Outcomes: M volume density (Mv) was assessed by electron microscopy from vastus lateralis biopsies, electron transport chain proteins (ETC) by western blotting, mRNAs for transcription factors involved in M biogenesis by qRT-PCR and in-vivo oxidative capacity (ATPmax) by (31)P-MR spectroscopy. Peak oxygen uptake (VO2peak) was measured by GXT. Results: VO2peak was strongly correlated with Mv in eighty 60-80 yo adults. Comparison of A vs. S revealed differences in Mv, ATPmax and some ETC complexes. Finally, exercise intervention confirmed that S are able to recover Mv, ATPmax and specific transcription factors. Conclusions: These data suggest that 1) aging per se is not the primary culprit leading to M dysfunction, 2) an aerobic exercise program, even at an older age, can ameliorate the loss in skeletal muscle M content and may prevent aging muscle comorbidities and 3) the improvement of M function is all about content.