Body Composition Across the Adult Lifespan in African Caribbean Men: The Tobago Longitudinal Study of Aging.

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.

Serum Vitamin D and Age-Related Muscle Loss in Afro-Caribbean Men: The Importance of Age and Diabetic Status.

BACKGROUND: Prospective studies examining the potential association of vitamin D with age-related muscle loss have shown inconsistent results. OBJECTIVE: To examine the association between baseline serum 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), and prospective change in lean mass with aging in African ancestry population. We also determined if associations were modulated by age and diabetes mellitus (DM). DESIGN: Prospective observational cohort study. SETTING: Data were collected from a random sub-sample of 574 men, participants of the Tobago Bone Health Study (TBHS). PARTICIPANTS: 574 Afro-Caribbean men, aged 43+ years (mean age: 59.1 ± 10.5), who were randomly selected as the participants in both the baseline and the follow-up visits. MEASUREMENTS: Baseline fasting serum 25(OH)D was measured using liquid chromatography mass spectrometry (LC-MS/MS), and and 1,25(OH)2D was measured using radioimmunosassay (RIA). Changes in dual-energy X-ray absorptiometry (DXA)-measured appendicular lean mass (ALM), and total body lean mass (TBLM) were measured over an average of 6.0 ± 0.5 years. The associations of 25(OH)D and 1,25(OH)2D with ALM and TBLM were assessed by multiple linear regression model after adjusting for potential confounders. RESULTS: When stratifying all men into two groups by age, greater baseline 25(OH)D and 1,25(OH)2D levels were associated with smaller losses of ALM and TBLM in older (age 60+ years) but not in younger (age 43 - 59 years) men. When stratifying by DM status, the associations of 25(OH)D and 1,25(OH)2D with declines in ALM and TBLM were statistically significant only in prediabetic, but not among normal glycemic or diabetic men. CONCLUSION: Higher endogenous vitamin D concentrations are associated with less lean mass loss with aging among older and prediabetic Afro-Caribbean men independent of potential confounders. Our findings raise a possibility that maintaining high serum vitamin D level might be important for musculoskeletal health in elderly and prediabetic African ancestry men.

Optimal serum cholesterol concentrations are associated with accelerated bone loss in African ancestry men.

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.

Relative influence of heritability, environment and genetics on serum sclerostin.

SUMMARY: We determined factors associated with serum sclerostin in 446 Afro-Caribbean family members. Age, weight, sex, diabetes and kidney function were associated with sclerostin. Sclerostin was heritable, and nine SNPs in the SOST gene region were associated with sclerostin. Variation in serum sclerostin is a heritable factor that is determined by both genetic and environmental factors. INTRODUCTION: Sclerostin, encoded by the SOST gene, is a Wnt inhibitor that regulates bone mineralization and is a candidate gene locus for osteoporosis. However, little is known about the genetic and non-genetic sources of inter-individual variation in serum sclerostin levels. METHODS: Serum sclerostin was measured in 446 Afro-Caribbean men and women aged 18+ from seven large, multigenerational families (mean family size, 64; 3,840 relative pairs). Thirty-six common single nucleotide polymorphisms (SNP) were genotyped within a 100 kb region encompassing the gene encoding sclerostin (SOST). Genetic and non-genetic factors were tested for association with serum sclerostin. RESULTS: Mean serum sclerostin was 41.3 pmol/l and was greater in men than in women (P < 0.05). Factors associated with higher serum sclerostin were increased age and body weight, male sex, diabetes and decreased glomerular filtration rate, which collectively accounted for 25.4 % of its variation. Residual genetic heritability of serum sclerostin was 0.393 (P < 0.0001). Nine SNPs reached nominal significance with sclerostin. Three of those nine SNPs represented independent association signals (rs851056, rs41455049 and rs9909172), which accounted for 7.8 % of the phenotypic variation in sclerostin, although none of these SNPs surpassed a Bonferroni correction for multiple comparisons. CONCLUSIONS: Serum sclerostin is a heritable trait that is also determined by environmental factors including age, sex, adiposity, diabetes and kidney function. Three independent common SNPs within the SOST region may collectively account for a significant proportion of the variation in serum sclerostin.

Association of volumetric bone mineral density with abdominal aortic calcification in African ancestry men.

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.

Skeletal muscle adiposity is associated with serum lipid and lipoprotein levels in Afro-Caribbean men.

OBJECTIVE: When compared with other ethnic groups, African ancestry individuals have lower triglycerides and higher High-density lipoprotein cholesterol (HDL-C) levels, although the mechanisms for these differences remain unclear. A comprehensive array of factors potentially related to fasting serum lipid and lipoprotein levels in African ancestry men was evaluated. DESIGN AND METHODS: Men (1,821) underwent dual-energy X-ray absorptiometry measures of total body fat and quantitative computed tomography assessments of calf skeletal muscle adiposity [subcutaneous and intermuscular adipose tissue (AT), and muscle density as a measure of intra-muscular AT]. RESULTS: Multivariable linear regression analysis identified age (-), total body fat (+), subcutaneous AT (-), fasting glucose (+), fasting insulin (+), diastolic blood pressure (+), and non-African ancestry (+) as independent correlates of triglycerides (all P < 0.05). Total body fat (+), intra-muscular AT (-), and diastolic blood pressure (+) were independent correlates of Low-density lipoprotein cholesterol (LDL-C) (all P < 0.001). Age (+), waist circumference (-), fasting insulin (-), physical activity (+), and alcohol intake (+) were independent correlates of HDL-C (all P < 0.05). CONCLUSIONS: A novel relationship between skeletal muscle adiposity and serum lipid and lipoprotein levels in African ancestry men, independent of total and central adiposity was illuminated. In African ancestry populations, genetic factors are likely a significant determinant of triglycerides levels.

Association analysis of 33 lipoprotein candidate genes in multi-generational families of African ancestry.

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.

[Problems in severe injuries of the radial nerve]. / Problemi kod teskih ostecenja n. radialisa.

By the presentation of the clinical material a series of 14 cases of the radial nerve microsurgical reparation has been analyzed with the reference to the modern achievements in this field and the possibilities of its quicker and better rehabilitation have been quoted. In our material we used the intraneural microsurgical technique with the direct funiculoraphy (3), the interfascicular nerve transplantation (8) and the external and internal microneurolysis (3). Twelve reconstructed radial nerves were evaluated by these methods. The successful motoric function (M3 and more), with the performance of will-power in the proximal and distal muscles, which spontaneously act on the resistance, and with the independent finger movements, have been detected in 84% of the cases in the period from 8 to 24 months after the reconstruction of this extensor nerve. The state of the contemporary micro-surgery prefers the timely and the exact neurological status, as well as the information on the extensiveness of the radial nerve lesion, on which bases the method for its functional restoration and anatomic rehabilitation should be determined.