Abdominal fat and hip fracture risk in the elderly: the Dubbo Osteoporosis Epidemiology Study.
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BACKGROUND: Fat mass, which is a major component of body weight, is directly related to bone mineral density and reduced fracture risk. It is not known whether abdominal fat is associated with hip fracture. The present study was designed to examine the association between abdominal fat and hip fracture in women and men aged 60+ years. METHODS: This was a nested case-control study with one fracture case being matched with two controls of the same age. In women 63 cases were matched with 126 controls, and in men 26 cases were matched with 52 controls. Hip fracture was confirmed by X-ray and personal interview. Other measurements included weight, height, body mass index (BMI), abdominal fat, and femoral neck bone density (FNBMD). Conditional logistic regression model was used to analyse data. RESULTS: The odds ratio of hip fracture risk associated with each 10% lower abdominal fat was 1.5 (95% CI, 1.1 to 2.1) in women and 1.2 (95% CI, 0.7 to 2.0) in men. However after adjusting for FNBMD or body weight, the abdominal fat-fracture association was no longer statistically significant. Similarly, body weight and BMI was each significantly associated with hip fracture risk (in women), but after taking with account the effect of FNBMD, the association become statistically non-significant. CONCLUSION: Lower abdominal fat was associated with an increased risk of hip fracture in elderly women, but the association was not independent of FNBMD or weight. The contribution of abdominal fat to hip fracture risk is likely to be modest. (+info)
Inactivity, exercise, and visceral fat. STRRIDE: a randomized, controlled study of exercise intensity and amount.
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Despite the importance of randomized, dose-response studies for proper evaluation of effective clinical interventions, there have been no dose-response studies on the effects of exercise amount on abdominal obesity, a major risk factor for metabolic syndrome, diabetes, and cardiovascular disease. One hundred seventy-five sedentary, overweight men and women with mild to moderate dyslipidemia were randomly assigned to participate for 6 mo in a control group or for approximately 8 mo in one of three exercise groups: 1) low amount, moderate intensity, equivalent to walking 12 miles/wk (19.2 km) at 40-55% of peak oxygen consumption; 2) low amount, vigorous intensity, equivalent to jogging 12 miles/wk at 65-80% of peak oxygen consumption; or 3) high amount, vigorous intensity, equivalent to jogging 20 miles/wk (32.0 km). Computed tomography scans were analyzed for abdominal fat. Controls gained visceral fat (8.6 +/- 17.2%; P = 0.001). The equivalent of 11 miles of exercise per week, at either intensity, prevented significant accumulation of visceral fat. The highest amount of exercise resulted in decreased visceral (-6.9 +/- 20.8%; P = 0.038) and subcutaneous (-7.0 +/- 10.8%; P < 0.001) abdominal fat. Significant gains in visceral fat over only 6 mo emphasize the high cost of continued inactivity. A modest exercise program, consistent with recommendations from the Centers for Disease Control/American College of Sports Medicine (CDC/ACSM), prevented significant increases in visceral fat. Importantly, a modest increase over the CDC/ACSM exercise recommendations resulted in significant decreases in visceral, subcutaneous, and total abdominal fat without changes in caloric intake. (+info)
Increased plasma adiponectin in response to pioglitazone does not result from increased gene expression.
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Plasma levels of adiponectin are lower in obese and insulin-resistant subjects compared with lean and insulin-sensitive ones. Thiazolidinediones increase plasma adiponectin levels in diabetic subjects, although the mechanism of this increased plasma adiponectin has not been well studied. In the present study, we compared the plasma levels and adipose tissue expression of adiponectin in subjects with normal (NGT) and impaired glucose tolerance (IGT) and also studied the effects of metformin and pioglitazone on plasma and adipose tissue mRNA level of adiponectin in IGT subjects. IGT subjects had lower plasma adiponectin levels compared with NGT subjects, and similarly IGT subjects had lower adiponectin mRNA levels. In contrast, the increased plasma levels of adiponectin in response to pioglitazone were not associated with increased adiponectin expression in adipose tissue. Metformin did not cause any change in plasma or expression levels of adiponectin. Other adipokines were examined, and both pioglitazone and metformin decreased plasma levels of resistin in IGT subjects, and pioglitazone (but not metformin) decreased plasma levels of leptin. These data suggest that pioglitazone increases plasma adiponectin levels by posttranscriptional regulation in contrast to transcriptional regulation of adiponectin in relation to insulin sensitivity in NGT vs. IGT subjects. (+info)
Rats with steroid-induced polycystic ovaries develop hypertension and increased sympathetic nervous system activity.
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BACKGROUND: Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder associated with ovulatory dysfunction, abdominal obesity, hyperandrogenism, hypertension, and insulin resistance. METHODS: Our objectives in this study were (1) to estimate sympathetic-adrenal medullary (SAM) activity by measuring mean systolic blood pressure (MSAP) in rats with estradiol valerate (EV)-induced PCO; (2) to estimate alpha1a and alpha2a adrenoceptor expression in a brain area thought to mediate central effects on MSAP regulation and in the adrenal medulla; (3) to assess hypothalamic-pituitary-adrenal (HPA) axis regulation by measuring adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels in response to novel-environment stress; and (4) to measure abdominal obesity, sex steroids, and insulin sensitivity. RESULTS: The PCO rats had significantly higher MSAP than controls, higher levels of alpha1a adrenoceptor mRNA in the hypothalamic paraventricular nucleus (PVN), and lower levels of alpha2a adrenoceptor mRNA in the PVN and adrenal medulla. After exposure to stress, PCO rats had higher ACTH and CORT levels. Plasma testosterone concentrations were lower in PCO rats, and no differences in insulin sensitivity or in the weight of intraabdominal fat depots were found. CONCLUSION: Thus, rats with EV-induced PCO develop hypertension and increased sympathetic and HPA-axis activity without reduced insulin sensitivity, obesity, or hyperandrogenism. These findings may have implications for mechanisms underlying hypertension in PCOS. (+info)
High prevalence of metabolic syndrome among men in Okinawa.
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We determined the prevalence of metabolic syndrome (MS) in Okinawa from cross-sectional results of an annual physical checkup. We also calculated the homeostasis model assessment ratio (HOMA-R) as an index of insulin resistance, and examined the relationship between HOMA-R and MS. We studied 3,839 men (mean age 49.2 years) and 3,146 women (mean age 50.0 years), a total of 6,985 people aged from 30 to 79 years, who underwent an annual physical checkup in our hospital between May 2003 and March 2004. The diagnosis of MS was based on the criteria in the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III: ATP III). Abdominal circumference was assessed in accordance with the diagnostic criteria of the Japan Society for the Study of Obesity. The prevalence of MS was 30.2% in men and 10.3% in women. Mean HOMA-R significantly increased with an increase in the number of ATP III risk factors. Logistic regression analysis with the independent variables of sex, age, and HOMA-R gave an odds ratio of MS of 3.6 for men, 1.4 for a 10-year age increment, and 2.0 for an elevation of HOMA-R above 1.0. (+info)
Short-term predictors of abdominal obesity in children.
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BACKGROUND: The aim of this study was to examine the short-term tracking of abdominal adiposity in children. METHODS: A total of 918 children (477 boys) aged 6-12 years at baseline were followed-up for 2 years. Central obesity was assessed by waist circumference (WaistC), whereas body fat distribution by waist-to-hip ratio. Maturity was assessed by the Khamis-Roche method. Parental fatness and children's cardiorespiratory fitness (CRF) were also evaluated. Multiple and logistic regressions were employed to identify the predictors of BMI and WaistC. RESULTS: Tracking of body fatness and body fat distribution was high (r = 0.69-0.86, P < 0.01). More boys remained obese than girls (P < 0.05), whereas a greater percentage of boys moved to a higher quartile of WaistC after the 2-year follow-up (22.0 vs 14.1%, P < 0.01). Sex, child's maturity and WaistC at baseline, CRF, and maternal BMI explained 76% of the variability in BMI and WaistC at the follow-up (n = 290). Children with high WaistC at baseline and low CRF presented 1.9- and 4.3-fold increased risk of remaining in the upper quartile of WaistC at the follow-up (P < 0.01; n = 552). CONCLUSION: Youth with increased WaistC at baseline and low CRF presented an increased chance of maintaining central obesity at the follow-up. More boys than girls moved into a higher quartile of abdominal obesity during the 2-year follow-up period and this should be taken into account in designing programmes for childhood obesity. (+info)
Effect of leptin on insulin resistance of muscle--direct or indirect?
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We examined the effect of leptin on the insulin resistance in skeletal muscles by measuring glucose transport. Male Wistar rats were fed rat chow or high-fat diets for 30 days. Before sacrifice, rats fed high-fat diet were subcutaneously injected with leptin (1 mg/kg b.w.) for 3 days. The glucose transport in epitrochlearis and soleus muscles did not differ in the experimental groups under basal conditions, however these values decreased significantly in the rats fed high-fat diet under insulin stimulation (p<0.01). Leptin treatment recovered the decreased glucose transport in epitrochlearis (p<0.05) and soleus muscles (p=0.08). Triglyceride concentrations in soleus muscles were increased significantly in the rats fed high-fat diet as compared to rats fed chow diet (p<0.01), and were decreased significantly by leptin treatment (p<0.01). The glucose transport was measured under basal conditions and after 60 microU/ml of insulin treatment with or without 50 ng/ml of leptin. Leptin had no direct stimulatory effect on glucose transport under both basal and insulin-stimulated conditions in vitro. These results demonstrate that leptin injection to rats fed high-fat diet recovered impaired insulin responsiveness of skeletal muscles and muscle triglyceride concentrations. However, there was no direct stimulatory effect of leptin on insulin sensitivity of skeletal muscles in vitro. (+info)
Administration of recombinant human GHRH-1,44-amide for 3 months reduces abdominal visceral fat mass and increases physical performance measures in postmenopausal women.
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OBJECTIVE: A recent study indicated that twice-daily s.c. administration of a high dose of recombinant human GHRH-1,44-amide (GHRH) for 90 days can alter body composition in healthy older men. No data establish whether this is also true in postmenopausal women. The present study tests the hypothesis that the same GHRH regimen applied in women will: (i) elevate both IGF-I and GH concentrations; and (ii) reduce abdominal visceral fat mass, augment total body water and enhance functional performance. DESIGN: Ten postmenopausal volunteers underwent baseline study and then received 1 mg GHRH twice daily s.c. for 3 months. METHODS: Statistical comparisons were made with pre-intervention baseline data. RESULTS: GHRH administration stimulated: (i) a mean 98 +/- 14% elevation of overnight GH concentrations after administration of the peptide for 1 and 3 months (P < 0.005); (ii) a sustained 71 +/- 3.5% rise in IGF-I concentrations over the interval from 2 weeks to 3 months (P < 0.0012); (iii) a 16 +/- 7% reduction in abdominal visceral fat mass (P = 0.029) and a 14 +/- 5% increase in tri-tiated water space (P < 0.025); (iv) an abbreviation of the times required to walk 30 m (P = 0.015) and ascend two flights of stairs (P = 0.003). Most (70%) subjects experienced local skin reactivity. There were no systemic adverse events. CONCLUSIONS: A 3-month regimen of GHRH supplementation in postmenopausal women can stimulate GH and IGF-I production, reduce abdominal visceral fat and improve selected measures of physical performance, while inducing significant local skin reactivity. (+info)