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AIM - Few epidemiological studies have investigated the association between circulating concentrations of the active vitamin D metabolite 1,25(OH)2D and metabolic syndrome. We sought to determine whether blood levels of 1,25(OH)2D are associated with metabolic syndrome and its individual components, including waist circumference, triglycerides, blood pressure, and glucose, and high-density lipoprotein. We also investigated these associations for the more abundant precursor vitamin D metabolite, 25(OH)D.
METHODS - Participants from two completed clinical trials of colorectal neoplasia with available metabolic syndrome data and blood samples for measurement of 1,25(OH)2D (n=1048) and 25(OH)D (n=2096) were included. Cross-sectional analyses of the association between concentrations of 1,25(OH)2D, 25(OH)D, metabolic syndrome, and its components were conducted.
RESULTS - A statistically significant inverse association was observed for circulating concentrations of 1,25(OH)2D and metabolic syndrome, with adjusted ORs (95% CIs) of 0.73 (0.52-1.04) and 0.52 (0.36-0.75) for the second and third tertiles of 1,25(OH)2D, respectively (p-trend <0.001). Significant inverse relationships were also observed between 1,25(OH)2D and high triglycerides (p-trend <0.001), and low high-density lipoprotein (p-trend <0.001). For 25(OH)D concentrations, significant inverse associations were found for metabolic syndrome (p-trend <0.01), high waist circumference (p-trend <0.04) and triglyceride levels (p-trend <0.01). Participants with 25(OH)D ≥30 ng/ml and in the highest tertile of 1,25(OH)2D demonstrated significantly lower odds of metabolic syndrome, with an OR (95% CI) of 0.38 (0.19-0.75) compared to those in the lowest category for both metabolites.
CONCLUSION - These results provide new evidence that the relatively rarely-studied active hormonal form of vitamin D, 1,25(OH)2D, is associated with metabolic syndrome and its components, and confirm prior findings for 25(OH)D. The finding that 1,25(OH)2D is related to high-density lipoprotein, while 25(OH)D is not, suggests that there may be an independent mechanism of action for 1,25(OH)2D in relation to metabolic dysregulation.
Copyright © 2015 Elsevier Inc. All rights reserved.
BACKGROUND AND OBJECTIVES - Modifiable factors, such as body size and body composition, could influence physical function and quality of life in patients undergoing maintenance hemodialysis (MHD).
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS - From January 2008 to June 2012, in body mass index (BMI), waist circumference (WC), and magnetic resonance imaging measurements of midthigh muscle area (MTMA) and intra-abdominal fat area (IAFA) were obtained at baseline in 105 MHD patients. Six-minute walk distances and physical and mental component scores (PCS and MCS) from the Short Form-12 questionnaire were obtained at baseline and 6 and 12 months. Separate mixed-effects regression models were used to relate baseline BMI, WC, and IAFA with baseline and the average of follow-up 6-minute walk distances and PCS and MCS after adjustment for baseline covariates and MTMA.
RESULTS - for baseline covariates and baseline MTMA, each SD increase in baseline BMI was inversely associated with baseline (-31.5 m; 95% confidence interval [95% CI], -53.0 to -10.0 m) and follow-up (-36.9 m; 95% CI, -54.6 to -19.2 m) 6-minute walk distances. Results were similar for WC and IAFA. In each of these models, each SD increase in MTMA had a strong positive association with 6-minute walk distance. Adiposity measures were not associated with baseline or follow-up PCS and MCS. After adjustment for baseline BMI, each SD increase in baseline MTMA was associated with higher baseline PCS score (3.78; 95% CI, 0.73 to 6.82) and MCS (3.75; 95% CI, 0.44 to 7.05) but had weaker associations with follow-up PCS and MCS.
CONCLUSIONS - Body size and composition are significantly associated with physical functioning and quality of life. Interventions that improve muscle mass and decrease obesity might improve these measures in patients undergoing MHD.
Copyright © 2014 by the American Society of Nephrology.
OBJECTIVE - Many studies have shown that low sex hormone-binding globulin (SHBG) is associated with insulin resistance, but only few studies have examined how serum SHBG is regulated by insulin in humans. This interventional study aimed to investigate the effect of insulin therapy (IT) on serum SHBG levels in newly diagnosed type 2 diabetic patients.
METHODS - A total of 80 newly diagnosed type 2 diabetic subjects were enrolled and randomly grouped into a 2-week intensive IT with/without metformin. Serum SHBG, total testosterone, glucose, liver enzymes, lipids, insulin, and C-peptide levels were measured before and after IT.
RESULTS - Before IT, serum SHBG levels were negatively correlated with BMI, waist circumference (WC), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (γ-GT), triglyceride (TG), fasting insulin, and C-peptide, and homeostatic model assessment of insulin resistance (HOMA-IR), and positively with HDL-C (all P for trend <0.05), after adjustment for age and sex. IT increased serum SHBG levels from 26.5±14.5 to 33.2±15.0 nmol/l (P<0.001), increased by 25.2% (95% CI, 20.3 to 30.9%, P<0.001). In a multiple linear regression model adjusting for age, sex, BMI, and WC, the decreases in ΔALT (standardized regression coefficient β=-0.374, P=0.012) and ΔTG (β=-0.380, P=0.020) were independent contributors to the increase in ΔSHBG.
CONCLUSIONS - IT increases serum SHBG likely through improving insulin resistance and liver function.
BACKGROUND - The childhood obesity epidemic disproportionately affects Hispanics. This paper reports on the design of the ongoing Healthy Families Study, a randomized controlled trial testing the efficacy of a community-based, behavioral family intervention to prevent excessive weight gain in Hispanic children using a community-based participatory research approach.
METHODS - The study will enroll 272 Hispanic families with children ages 5-7 residing in greater Nashville, Tennessee, United States. Families are randomized to the active weight gain prevention intervention or an alternative intervention focused on oral health. Lay community health promoters implement the interventions primarily in Spanish in a community center. The active intervention was adapted from the We Can! parent program to be culturally-targeted for Hispanic families and for younger children. This 12-month intervention promotes healthy eating behaviors, increased physical activity, and decreased sedentary behavior, with an emphasis on parental modeling and experiential learning for children. Families attend eight bi-monthly group sessions during four months then receive information and/or support by phone or mail each month for eight months. The primary outcome is change in children's body mass index. Secondary outcomes are changes in children's waist circumference, dietary behaviors, preferences for fruits and vegetables, physical activity, and screen time.
RESULTS - Enrollment and data collection are in progress.
CONCLUSION - This study will contribute valuable evidence on efficacy of a childhood obesity prevention intervention targeting Hispanic families with implications for reducing disparities.
Copyright © 2013 Elsevier Inc. All rights reserved.
OBJECTIVE - The objective was to evaluate the association of body size and fat distribution with the risk of colorectal cancer (CRC) in Chinese men and women.
DESIGN - This was a population-based, prospective cohort study.
SUBJECTS - The analysis included 134,255 Chinese adults enrolled in the Shanghai Women's Health Study and the Shanghai Men's Health Study, with an average follow-up of 11.0 and 5.5 years, respectively.
MEASUREMENTS - Waist circumference (WC), body mass index (BMI) and waist-to-hip ratio (WHR) were measured by trained interviewers at baseline. Multivariable Cox models were used to calculate adjusted hazard ratios (HRs) for incident CRC.
RESULTS - A total of 935 incident CRC cases were identified. Both measures of general adiposity (measured by BMI) and central adiposity (measured by WHR and WC) were significantly associated with an increased risk of colon cancer in men but not in women. Multivariable-adjusted HRs for colon cancer in men in the highest compared with the lowest quintiles were 2.15 (95% confidence interval (CI): 1.35-3.43; P for trend=0.0006) for BMI, 1.97 (95% CI: 1.19-3.24; P for trend=0.0004) for WHR and 2.00 (95% CI: 1.21-3.29; P for trend=0.0002) for WC. The BMI-associated risk was attenuated in analyses stratified by WHR, whereas the WHR-associated risk remained significant in the high BMI stratum (HR for comparison of extreme tertiles of WHR: 3.38, 95% CI: 1.47-7.75; P for trend =0.0002). None of these anthropometric measures were significantly associated with rectal cancer.
CONCLUSION - Obesity, particularly central obesity, was associated with an increased risk of colon cancer in men.
BACKGROUND - Abnormal sleep duration, either long or short, is associated with disease risk and mortality. Little information is available on sleep duration and its correlates among Chinese women.
METHODS - Using information collected from 68,832 women who participated in the Shanghai Women's Health Study (SWHS), we evaluated sleep duration and its correlations with sociodemographic and lifestyle factors, health status, and anthropometric measurements and their indexes using polynomial logistic regression.
RESULTS - The mean age of the study population was 59.6 years (SD=9.0; range: 44.6-79.9 years) at time of sleep duration assessment. Approximately 80% of women reported sleeping 6-8 h/day, 11.5% slept 5h or less, and 8.7% slept 9h or more. As expected, age was the strongest predictor for sleep duration and was negatively correlated with sleep duration. In general, sleep duration was positively associated with energy intake, intakes of total meat and fruits, body mass index (BMI), waist-hip ratio (WHR), and waist circumference (WC) after adjustment for age and other factors. Both short and long sleep duration were negatively associated with education level, family income, and leisure-time physical activity and positively associated with number of live births, history of night shift work, and certain chronic diseases, compared to sleep duration around 7 h/day (6.5-7.4h/day). Short sleep duration was related to tea consumption and passive smoking. Long sleep duration was related to menopausal status and marital status.
CONCLUSIONS - In this large, population-based study, we found that sleep duration among middle-aged and elderly Chinese women was associated with several sociodemographic and lifestyle factors and with disease status. The main limitation of the study is the cross-sectional design that does not allow us to draw any causal inference. However, this study provides information for future investigation into the nature of these associations so that recommendations can be developed to reduce sleep problems in middle-aged and elderly Chinese women. It also provides important information on potential confounders for investigation of sleep duration on health outcomes in this population.
Copyright © 2012 Elsevier B.V. All rights reserved.
BACKGROUND - Although metabolic risk factors are known to cluster in individuals who are prone to developing diabetes mellitus and cardiovascular disease, the underlying biological mechanisms remain poorly understood.
METHODS AND RESULTS - To identify pathways associated with cardiometabolic risk, we used liquid chromatography/mass spectrometry to determine the plasma concentrations of 45 distinct metabolites and to examine their relation to cardiometabolic risk in the Framingham Heart Study (FHS; n=1015) and the Malmö Diet and Cancer Study (MDC; n=746). We then interrogated significant findings in experimental models of cardiovascular and metabolic disease. We observed that metabolic risk factors (obesity, insulin resistance, high blood pressure, and dyslipidemia) were associated with multiple metabolites, including branched-chain amino acids, other hydrophobic amino acids, tryptophan breakdown products, and nucleotide metabolites. We observed strong associations of insulin resistance traits with glutamine (standardized regression coefficients, -0.04 to -0.22 per 1-SD change in log-glutamine; P<0.001), glutamate (0.05 to 0.14; P<0.001), and the glutamine-to-glutamate ratio (-0.05 to -0.20; P<0.001) in the discovery sample (FHS); similar associations were observed in the replication sample (MDC). High glutamine-to-glutamate ratio was associated with lower risk of incident diabetes mellitus in FHS (odds ratio, 0.79; adjusted P=0.03) but not in MDC. In experimental models, administration of glutamine in mice led to both increased glucose tolerance (P=0.01) and decreased blood pressure (P<0.05).
CONCLUSIONS - Biochemical profiling identified circulating metabolites not previously associated with metabolic traits. Experimentally interrogating one of these pathways demonstrated that excess glutamine relative to glutamate, resulting from exogenous administration, is associated with reduced metabolic risk in mice.
BACKGROUND - Established risk factors for prostate cancer have not translated to effective prevention or adjuvant care strategies. Several epidemiologic studies suggest greater body adiposity may be a modifiable risk factor for high-grade (Gleason 7, Gleason 8-10) prostate cancer and prostate cancer mortality. However, BMI only approximates body adiposity, and may be confounded by centralized fat deposition or lean body mass in older men. Our objective was to use bioelectric impedance analysis (BIA) to measure body composition and determine the association between prostate cancer and total body fat mass (FM) fat-free mass (FFM), and percent body fat (%BF), and which body composition measure mediated the association between BMI or waist circumference (WC) with prostate cancer.
METHODS - The study used a multi-centered recruitment protocol targeting men scheduled for prostate biopsy. Men without prostate cancer at biopsy served as controls (n = 1057). Prostate cancer cases were classified as having Gleason 6 (n = 402), Gleason 7 (n = 272), or Gleason 8-10 (n = 135) cancer. BIA and body size measures were ascertained by trained staff prior to diagnosis, and clinical and comorbidity status were determined by chart review. Analyses utilized multivariable linear and logistic regression.
RESULTS - Body size and composition measures were not significantly associated with low-grade (Gleason 6) prostate cancer. In contrast, BMI, WC, FM, and FFM were associated with an increased risk of Gleason 7 and Gleason 8-10 prostate cancer. Furthermore, BMI and WC were no longer associated with Gleason 8-10 (OR(BMI) = 1.039 (1.000, 1.081), OR(WC) = 1.016 (0.999, 1.033), continuous scales) with control for total body FFM (OR(BMI) = 0.998 (0.946, 1.052), OR(WC) = 0.995 (0.974, 1.017)). Furthermore, increasing FFM remained significantly associated with Gleason 7 (OR(FFM) = 1.030 (1.008, 1.052)) and Gleason 8-10 (OR(FFM) = 1.044 (1.014, 1.074)) after controlling for FM.
CONCLUSIONS - Our results suggest that associations between BMI and WC with high-grade prostate cancer are mediated through the measurement of total body FFM. It is unlikely that FFM causes prostate cancer, but instead provides a marker of testosterone or IGF1 activities involved with retaining lean mass as men age.
Insulin resistance is linked to general and abdominal obesity, but its relation to hepatic lipid content and pericardial adipose tissue is less clear. The purpose of this study was to examine cross-sectional associations of liver attenuation, pericardial adipose tissue, BMI, and waist circumference with insulin resistance. We measured liver attenuation and pericardial adipose tissue using the existing cardiac computed tomography scans in 5,291 individuals free of clinical cardiovascular disease and diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA) during the study's baseline visit (2000-2002). Low liver attenuation was defined as the lowest quartile and high pericardial adipose tissue as the upper quartile of volume (cm(3)). We used standard clinical definitions for obesity and abdominal obesity. Insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMA(IR)) index. In multivariate linear regression with all adiposity measures in the model simultaneously, all adiposity measures were significantly (P < 0.0001) associated with insulin resistance: regression coefficients (±s.e.) were 0.31 (±0.02) for low liver attenuation, 0.27 (±0.02) for high pericardial adipose tissue, 0.27 (±0.02) for obesity, and 0.32 (±0.02) for abdominal obesity. We found significant differences (P = 0.003) between standardized liver attenuation and insulin resistance by ethnicity: regression coefficients per 1 s.d. increment were 0.10 ± 0.01 for whites, 0.11 ± 0.02 for Chinese, 0.08 ± 0.2 for blacks, and 0.14 ± 0.01 for Hispanics. Liver attenuation and pericardial adipose tissue were associated with insulin resistance, independent of BMI and waist circumference.
Inflammation biomarkers, including higher high-sensitivity C-reactive protein (hsCRP) levels, higher white blood cell (WBC) counts, and lower serum albumin levels, are associated with an increased risk of all-cause mortality. Many studies have examined these biomarkers individually, but less is known about their joint association with mortality. hsCRP, WBC count, and serum albumin were measured at baseline in the Reasons for Geographic and Racial Differences in Stroke Study cohort members, who were enrolled in 2003-2007. Over 4.5 years, there were 1,062 deaths in 17,845 participants. High-risk categories were defined as hsCRP or WBC levels above the 75th percentile (5.1 mg/L and 6.9 × 10(9) cells/L, respectively) and albumin levels below the 25th percentile (4.00 g/dL). The authors derived 4 groups that corresponded to 0 (n = 8,341), 1 (n = 6,277), 2 (n = 2,635), or 3 (n = 592) biomarkers in the high-risk category. After adjustment for age, sex, waist circumference, race, region, smoking, alcohol use, income, educational level, physical activity frequency, and medical history and compared with those with no biomarkers in the high-risk category, the hazard ratios for all-cause mortality for 1, 2, and 3 biomarkers in the high-risk category were 1.56 (95% confidence interval: 1.33, 1.82), 2.19 (95% confidence interval: 1.84, 2.62), and 2.96 (95% confidence interval: 2.30, 3.80), respectively (P(trend) < 0.0001). Adding the 3 inflammation biomarkers to a fully adjusted model improved risk discrimination by 23.7% (95% confidence interval: 9.3, 39.9). Measurement of more than 1 biomarker is more useful in risk prediction than single biomarkers.