RESUMEN
Body composition and muscle strength change vary by age and ethnicity, and have a major impact on health and physical function. Little is known about the patterns of these changes in African-ancestry populations. Herein, we examined age-specific (5-year age groups) rates-of-change in lean and fat mass in 1918 African-ancestry men on the Caribbean island of Tobago (baseline age: 62.0±11.8 years, range: 40-99 years). Body composition (DXA) and grip strength were measured at three time points (baseline, 4- and 9-year follow-up). Annualized rates of change were calculated with all 3 time-points using Generalized Estimating Equations. We found that whole body lean mass declined at constant rate until age 65 (-0.72%/year; 95% CI: -0.76, -0.67), which accelerated to -0.92 %/year (-1.02, -0.82) among those 65-69, and again to -1.16 %/year (-1.30, -1.03 ) among those aged 70+. Whole body fat mass increased by a near constant rate of 2.93 %/year (2.72, 3.15%) across the lifespan. Finally, grip strength decline accelerated at age 50, and about 2x faster than lean mass through the lifespan after the age of 50. To conclude, in African-Caribbean men, the acceleration in muscle strength decline precedes the acceleration in lean mass decline by 10-15 years, suggesting decrements in factors other than lean mass drive this initial acceleration in muscle strength decline. We also found that African-Caribbean men undergo a constant shift to a more adipogenic phenotype throughout the adult lifespan (aged 40-99), which likely contributes to age-related loss of muscle and physical function.
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Composición Corporal , Longevidad , Anciano , Anciano de 80 o más Años , Envejecimiento , Humanos , Estudios Longitudinales , Masculino , Trinidad y TobagoRESUMEN
UNLABELLED: We tested if serum lipid and lipoprotein cholesterol levels are associated with longitudinal measures of bone mineral density (BMD) in 1289 African ancestry men. After 6 years of mean follow-up, men with clinically optimal levels of low-density lipoprotein (LDL), high-density lipoprotein (HDL), or triglycerides at baseline experienced the greatest BMD loss, independent of potential confounding factors (all p < 0.05). INTRODUCTION: Studies of lipid and lipoprotein cholesterol associations with bone mineral density (BMD) and bone loss have been inconclusive, and longitudinal data are sparse. Therefore, the aim of this study was to test if fasting serum lipid and lipoprotein cholesterol levels are associated with areal and volumetric BMD and BMD change. METHODS: We determined the association of serum triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol concentrations with cross-sectional and longitudinal (mean follow-up, 6.1 years) measures of BMD in a cohort of 1289 in African ancestry men (mean age, 56.4 years). Fasting serum triglycerides, HDL, and LDL were measured at baseline concurrent with BMD assessments. Dual-energy X-ray absorptiometry was used to quantify integral hip BMD, and peripheral quantitative computed tomography at the radius and tibia was used to quantify volumetric BMD. Men were categorized as optimal, borderline, or high risk for triglyceride, HDL, and LDL concentrations based on Adult Treatment Panel III guidelines. RESULTS: Lower serum triglyceride or LDL and higher HDL concentrations were associated with lower trabecular BMD at baseline (all p < 0.05). Similarly, men classified as having optimal levels of LDL, HDL, or triglycerides at baseline experienced the greatest integral BMD loss at the hip and trabecular BMD loss at the tibia (all p < 0.05), independent of potential confounding factors. CONCLUSIONS: We found that clinically optimal serum lipid and lipoprotein cholesterol concentrations were associated with accelerated bone loss among Afro-Caribbean men. Further studies are needed to better understand the mechanisms involved and potential clinical significance of these findings.
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Población Negra/estadística & datos numéricos , Enfermedades Óseas Metabólicas/sangre , Enfermedades Óseas Metabólicas/etnología , Colesterol/sangre , Absorciometría de Fotón/métodos , Adulto , Anciano , Anciano de 80 o más Años , Densidad Ósea/fisiología , LDL-Colesterol/sangre , Estudios de Seguimiento , Humanos , Lípidos/sangre , Lipoproteínas/sangre , Masculino , Persona de Mediana Edad , Triglicéridos/sangre , Trinidad y Tobago/epidemiologíaRESUMEN
SUMMARY: To determine whether there are race/ethnic differences in bone mineral density (BMD) by fracture history in men aged 65 years and older, we performed cross-sectional analysis in five large independent cohorts. Low BMD was associated with a higher prevalence of fracture in all cohorts, and the magnitude of the BMD differences by fracture status was similar across groups. INTRODUCTION: We aimed to determine whether there are race/ethnic and geographic differences in bone mineral density by fracture history in men aged 65 years and older. METHOD: The datasets included the Osteoporotic Fractures in Men (MrOS) Study (5,342 White, 243 African-American, 190 Asian, and 126 Hispanic), MrOS Hong Kong (1,968 Hong Kong Chinese), Tobago Bone Health Study (641 Afro-Caribbean), Namwon Study (1,834 Korean), and Dong-gu Study (2,057 Korean). The two Korean cohorts were combined. RESULTS: The prevalence of self-reported non-traumatic fracture was US white, 17.1 %; Afro-Caribbean, 5.5 %; US African-American, 15.1 %; US Hispanic, 13.7 %; US Asian, 10.5 %; Hong Kong Chinese, 5.6 %, and Korean, 5.1 %. The mean differences in hip and lumbar spine BMD between subjects with fracture and without fracture were statistically significant in all cohorts except US African American and US Asian men. There was a significant race/ethnic interaction for lumbar spine BMD by fracture status (p for interaction = 0.02), which was driven by the small number of Hispanic men. There was no interaction for femoral neck or total hip BMD. There were no significant race/ethnic differences in the odds ratio of fracture by BMD. CONCLUSIONS: Low BMD was associated with a higher prevalence of fracture in all cohorts and the magnitude of the BMD differences by fracture status was similar across groups suggesting homogeneity in the BMD-fracture relationship among older men.
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Densidad Ósea/fisiología , Osteoporosis/etnología , Fracturas Osteoporóticas/etnología , Anciano , Anciano de 80 o más Años , Envejecimiento/etnología , Envejecimiento/fisiología , Pueblo Asiatico/estadística & datos numéricos , Población Negra/estadística & datos numéricos , Estudios Transversales , Cuello Femoral/fisiopatología , Articulación de la Cadera/fisiopatología , Hong Kong/epidemiología , Humanos , Vértebras Lumbares/fisiopatología , Masculino , Osteoporosis/fisiopatología , Fracturas Osteoporóticas/fisiopatología , Trinidad y Tobago/epidemiología , Estados Unidos/epidemiología , Población Blanca/estadística & datos numéricosRESUMEN
SUMMARY: We tested for association between cortical and trabecular volumetric bone mineral density (vBMD) with abdominal aortic calcification (AAC) prevalence in 278 Afro-Caribbean men. AAC was present in 68.3 % of the men. Greater cortical, but not trabecular, vBMD was associated with significantly decreased odds of AAC independent of traditional risk factors. INTRODUCTION: The aim of this study is to assess the prevalence and correlates of AAC in a sample of 278 Afro-Caribbean men (mean age 56) and to test for a largely unexplored association between cortical and trabecular vBMD with AAC prevalence. METHODS: Men were recruited consecutively as part of an ongoing prospective cohort study of body composition in men aged 40+. For this analysis, AAC was assessed by computed tomography of the abdomen from L3 to S1. Aortic calcium was scored using the Agatston method, and prevalence was defined as a score ≥10 to rule out false positives. Men also had BMD assessed using peripheral quantitative computed tomography at 4 % (trabecular vBMD) and 33 % (cortical vBMD) of the radius and tibia. RESULTS: Abdominal aortic calcification was present in 68.3 % of the men. Significant independent predictors of AAC prevalence were increased age, increased BMI, hypertension, and current smoking. Age was the strongest predictor, with each SD (7.8 year) increase in age conferring 2.7 times increased odds of having AAC (P < 0.0001). A one SD greater cortical, but not trabecular, vBMD was associated with a significant decreased odds of AAC prevalence independent of other traditional risk factors (OR 0.65; 95 % CI 0.45-0.92). CONCLUSIONS: Cortical vBMD is inversely associated with AAC presence. This finding suggests that there may be shared physiology between cortical bone compartment remodeling and vascular calcification.
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Enfermedades de la Aorta/fisiopatología , Densidad Ósea/fisiología , Calcificación Vascular/fisiopatología , Adulto , Anciano , Aorta Abdominal , Enfermedades de la Aorta/etnología , Población Negra/estadística & datos numéricos , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Prospectivos , Factores de Riesgo , Tomografía Computarizada por Rayos X/métodos , Trinidad y Tobago/epidemiología , Calcificación Vascular/etnologíaRESUMEN
UNLABELLED: We examined the association of serum 25-hydroxyvitamin D [25(OH)D] with indices of bone quality in older men. Positive associations for 25(OH)D and bone mineral density, content, cortical thickness, and axial and polar strength strain indices were observed among Caucasians; however, among men of African descent findings were either null or negative. INTRODUCTION: There are limited data on serum 25(OH)D and bone measures in men of African ancestry. To better understand racial differences in vitamin D status and bone health, a cross-sectional study among 446 Caucasian men in the US and 496 men of African ancestry in Tobago (age ≥ 65 years) was conducted. METHODS: Serum 25(OH)D (liquid chromatography and tandem mass spectrometry) was measured, and peripheral quantitative computed tomography scans were administered. Bone measures estimated included trabecular and cortical volumetric bone mineral density (vBMD), bone mineral content (BMC), bone geometry (cross-sectional area and cortical thickness), and polar and axial strength strain indices (SSIp and SSIx). RESULTS: Men of African ancestry had higher 25(OH)D than Caucasians (34.7 vs. 27.6 ng/ml, p < 0.01). Among Caucasians, 25(OH)D was positively (p trend < 0.05) associated with cortical vBMD, total BMC, cortical thickness, SSIp, and SSIx at the distal radius after adjustment for potential confounders. Similar patterns were observed at the distal tibia. In contrast, in men of African ancestry, there was an inverse association (p trend < 0.05) between 25(OH)D and the cross-sectional area, and SSIx. Race modified (p for interaction < 0.05) the association between 25(OH)D and total BMC, cross-sectional area, SSIp, SSIx, and trabecular vBMD of the radius. In men of African ancestry, there was evidence of a threshold effect (at approximately 18 ng/ml) for 25(OH)D on tibial total BMC and cortical thickness. CONCLUSIONS: More studies are needed to better comprehend these race differences for 25(OH)D and bone density, geometry, and indices of bone strength.
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Densidad Ósea/fisiología , Radio (Anatomía) , Tibia , Vitamina D/análogos & derivados , Anciano , Población Negra , Estudios Transversales , Humanos , Masculino , Pennsylvania , Radio (Anatomía)/anatomía & histología , Radio (Anatomía)/fisiología , Tibia/anatomía & histología , Tibia/fisiología , Trinidad y Tobago/etnología , Vitamina D/sangre , Población BlancaRESUMEN
African ancestry individuals have a more favorable lipoprotein profile than Caucasians, although the mechanisms for these differences remain unclear. We measured fasting serum lipoproteins and genotyped 768 tagging or potentially functional single nucleotide polymorphisms (SNPs) across 33 candidate gene regions in 401 Afro-Caribbeans older than 18 years belonging to 7 multi-generational pedigrees (mean family size 51, range 21-113, 3,426 relative pairs). All lipoproteins were significantly heritable (P<0.05). Gender-specific analysis showed that heritability for triglycerides was much higher (P<0.01) in women than in men (women, 0.62+/-0.18, P<0.01; men, 0.13+/-0.17, P>0.10), but the heritability for LDL cholesterol (LDL-C) was higher (P<0.05) in men than in women (men, 0.79+/-0.21, P<0.01; women, 0.39+/-0.12, P<0.01). The top 14 SNPs that passed the false discovery rate threshold in the families were then tested for replication in an independent population-based sample of 1,750 Afro-Caribbean men aged 40+ years. Our results revealed significant associations for three SNPs in two genes (rs5929 and rs6511720 in LDLR and rs7517090 in PCSK9) and LDL-C in both the family study and in the replication study. Our findings suggest that LDLR and PCSK9 variants may contribute to a variation in LDL-C among African ancestry individuals. Future sequencing and functional studies of these loci may advance our understanding of genetic factors contributing to LDL-C in African ancestry populations.
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Población Negra/genética , Estudios de Asociación Genética , Lipoproteínas/genética , Polimorfismo de Nucleótido Simple , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , LDL-Colesterol/sangre , LDL-Colesterol/genética , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Lipoproteínas/sangre , Masculino , Persona de Mediana Edad , Linaje , Trinidad y Tobago , Adulto JovenRESUMEN
Osteoporotic fractures are less prevalent in African Americans than in caucasians, possibly because of differences in bone structural strength. Bone structural adaptation can be attributed to changes in load, crudely measured as lean and fat mass throughout life. The purpose of this analysis was to describe the associations of leg lean mass, total body fat mass, and hours walked per week with femoral bone mineral density (BMD) and bone geometry in a cross-sectional sample of 1,748 men of African descent between the ages of 40 and 79 years. BMD, section modulus (Z), cross-sectional area (CSA), and subperiosteal width were measured from dual energy X-ray absortiometry (DXA) scans using the hip structural analysis (HSA) program. Multiple linear regression models explained 35% to 48% of the variance in bending (Z) and axial (CSA) strength at the femoral neck and shaft. Independent of all covariates including total body fat mass, one standard deviation increase in leg lean mass was significantly associated with a 5% to 8% higher Z, CSA, and BMD (P < 0.010) at the neck and shaft. The number of hours walked per week was not a strong or consistent independent predictor of bone geometry or BMD. We have shown that weight is the strongest independent predictor of femur BMD and geometric strength although the effect appears to be mediated by lean mass since leg lean mass fraction and total body fat mass fraction had significant and opposing effects at the narrow neck and shaft in this group of middle aged and elderly men.
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Composición Corporal , Fémur/anatomía & histología , Actividad Motora/fisiología , Absorciometría de Fotón , Adulto , Anciano , Densidad Ósea , Fuerza Compresiva/fisiología , Femenino , Fémur/diagnóstico por imagen , Fémur/fisiología , Humanos , Persona de Mediana Edad , Osteoporosis/diagnóstico por imagen , Osteoporosis/epidemiología , Osteoporosis/patología , Docilidad/efectos de la radiación , Trinidad y Tobago/epidemiología , Caminata/fisiologíaRESUMEN
Numerous studies have examined factors regulating high-density lipoprotein cholesterol (HDL-C) levels in male endurance athletes, but few studies have examined HDL-C regulation in female athletes. The present study compared lipid and lipoprotein concentrations, postheparin lipolytic activities, and the clearance rate (K2) of triglycerides following an intravenous fat infusion in 12 female distance runners (aged 33 +/- 9 years, mean +/- SD) and 13 sedentary women (33 +/- 9 years). Runners were leaner and had greater maximum oxygen uptake values than controls. Runners also had nonsignificantly lower triglyceride (53 +/- 15 v 65 +/- 13 mg/dL) and higher HDL-C (62 +/- 14 v 52 +/- 8 mg/dL, P = .06). Lipoprotein lipase activity (LPLA) was 33% greater (P < .05) and fat clearance (K2) was 27% faster (P < .01) in the trained women, and LPLA correlated directly with K2 (r = .61) and HDL-C (r = .62) in this group (P < .05 for both). K2 was directly related to HDL-C in the athletes (r = .57, P = .06), and also when the active and sedentary women were combined (r = .43, P < .05). These results suggest that increased LPLA and enhanced plasma triglyceride clearance may contribute to the HDL-C levels of physically active premenopausal women.