Cardiometabolic risk factors and fat distribution in children and adolescents.

OBJECTIVES: To determine if cardiometabolic risk factors have differential associations with the proportion of fat distributed in the trunk, leg, and arm, in White and African American children and adolescents. STUDY DESIGN: The sample included 391 White and African American 5- to 18 year-olds. Total and regional (trunk, leg, and arm) fat were measured by dual energy X-ray absorptiometry. Resting blood pressure and fasting triglycerides, high density lipoprotein cholesterol (HDL-C), glucose, insulin, and C-reactive protein were measured in a clinical setting. Insulin resistance was determined with the homeostatic model of insulin resistance. Multivariable linear and logistic regression models were used to examine associations between each cardiometabolic risk factor and proportion of fat (trunk, leg, or arm fat divided by whole body fat), with whole body fat, age, sex, race, sexual maturity status, and self-reported physical activity as covariates. RESULTS: Higher odds of low HDL-C, high triglycerides, insulin resistance, and high C-reactive protein were associated with % trunk fat. Lower odds of low HDL-C, high triglycerides, and insulin resistance were associated with % leg fat. No cardiometabolic risk factor was associated with % arm fat. CONCLUSIONS: Cardiometabolic risk factors in children and adolescents were attenuated when a larger proportion of fat was distributed in the leg. The clinical assessment of children's fat distribution may be useful in determining cardiometabolic risk.

Predisease conditions and serum vitamin D levels in healthy Mexican American adults.

AIMS: To elucidate the relationship between low circulating serum vitamin D levels and predisease conditions (ie, prediabetes and prehypertension) in healthy Mexican American adults. METHODS: Analyses were conducted using data from the United States National Health and Nutrition Examination Survey (NHANES) from 2001 through 2006. Free-living (ie, community-dwelling, nonimprisoned) adult Mexican American subjects (N = 788; men, n = 443; women, n = 345) who had provided written informed consent and had no history of diabetes, hypertension, dyslipidemia, metabolic syndrome, and/or cardiovascular disease were included in this report. Participants were not ingesting any prescription medications, nor did they exhibit any evidence of malabsorption. Participants were determined to be disease free. RESULTS: The mean serum vitamin D level for Mexican American adults (N = 788) of 50.5 nmol/L was significantly higher (P < 0.0001) than the mean of 35.9 nmol/L for non-Hispanic black adults (n = 621), and significantly lower (P < 0.0001) than the mean of 65.0 nmol/L for non-Hispanic white adults (n = 1711). Although age, sex, and body mass index were all significantly associated with prehypertension and prediabetes, no such association was found for serum vitamin D levels. CONCLUSION: A successive, incremental shift of approximately 15 nmol/L in vitamin D distribution was seen in the transition from the dark-skinned non-Hispanic black population to the brown-skinned Mexican American population, and from the brown-skinned Mexican American population to the non-Hispanic white population. In contrast to the non-Hispanic black and non-Hispanic white populations, wherein previous studies found that serum vitamin D levels below the 75th percentile were associated with prediabetes and prehypertension, no such association was detected among the Mexican American population. The reason for this lack of association among the Mexican American population is unclear.

Long-term renal and cardiovascular outcomes in Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) participants by baseline estimated GFR.

BACKGROUND AND OBJECTIVES: CKD is common among older patients. This article assesses long-term renal and cardiovascular outcomes in older high-risk hypertensive patients, stratified by baseline estimated GFR (eGFR), and long-term outcome efficacy of 5-year first-step treatment with amlodipine or lisinopril, each compared with chlorthalidone. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a long-term post-trial follow-up of hypertensive participants (n=31,350), aged ≥55 years, randomized to receive chlorthalidone, amlodipine, or lisinopril for 4-8 years at 593 centers. Participants were stratified by baseline eGFR (ml/min per 1.73 m(2)) as follows: normal/increased (≥90; n=8027), mild reduction (60-89; n=17,778), and moderate/severe reduction (<60; n=5545). Outcomes were cardiovascular mortality (primary outcome), total mortality, coronary heart disease, cardiovascular disease, stroke, heart failure, and ESRD. RESULTS: After an average 8.8-year follow-up, total mortality was significantly higher in participants with moderate/severe eGFR reduction compared with those with normal and mildly reduced eGFR (P<0.001). In participants with an eGFR <60, there was no significant difference in cardiovascular mortality between chlorthalidone and amlodipine (P=0.64), or chlorthalidone and lisinopril (P=0.56). Likewise, no significant differences were observed for total mortality, coronary heart disease, cardiovascular disease, stroke, or ESRD. CONCLUSIONS: CKD is associated with significantly higher long-term risk of cardiovascular events and mortality in older hypertensive patients. By eGFR stratum, 5-year treatment with amlodipine or lisinopril was not superior to chlorthalidone in preventing cardiovascular events, mortality, or ESRD during 9-year follow-up. Because data on proteinuria were not available, these findings may not be extrapolated to proteinuric CKD.

Role of skeletal muscle mitochondrial density on exercise-stimulated lipid oxidation.

Reduced skeletal muscle mitochondrial density is proposed to lead to impaired muscle lipid oxidation and increased lipid accumulation in sedentary individuals. We assessed exercise-stimulated lipid oxidation by imposing a prolonged moderate-intensity exercise in men with variable skeletal muscle mitochondrial density as measured by citrate synthase (CS) activity. After a 2-day isoenergetic high-fat diet, lipid oxidation was measured before and during exercise (650 kcal at 50% VO(2)max) in 20 healthy men with either high (HI-CS = 24 ± 1; mean ± s.e.) or low (LO-CS = 17 ± 1 nmol/min/mg protein) muscle CS activity. Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Respiratory exchange data and blood samples were collected at rest and throughout the exercise. HI-CS subjects had higher VO(2)max (50 ± 1 vs. 44 ± 2 ml/kg fat free mass/min; P = 0.01), lower fasting respiratory quotient (RQ) (0.81 ± 0.01 vs. 0.85 ± 0.01; P = 0.04) and higher ex vivo muscle palmitate oxidation (866 ± 168 vs. 482 ± 78 nmol/h/mg muscle; P = 0.05) compared to LO-CS individuals. However, whole-body exercise-stimulated lipid oxidation (20 ± 2 g vs. 19 ± 1 g; P = 0.65) and plasma glucose, lactate, insulin, and catecholamine responses were similar between the two groups. In conclusion, in response to the same energy demand during a moderate prolonged exercise bout, reliance on lipid oxidation was similar in individuals with high and low skeletal muscle mitochondrial density. This data suggests that decreased muscle mitochondrial density may not necessarily impair reliance on lipid oxidation over the course of the day since it was normal under a high-lipid oxidative demand condition. Twenty-four-hour lipid oxidation and its relationship with mitochondrial density need to be assessed.