Insulin resistance, leptin and monocyte chemotactic protein-1 levels in diabetic and non-diabetic Afro-Caribbean subjects

AIM: To determine how the levels of leptin and monocyte chemotactic protein-1 (MCP-1) are associated with insulin resistance (IR) in obese, non-obese, diabetic and non-diabetic subjects. METHODS: 112 type 2 diabetics and 43 non-diabetics were studied fasting. Anthropometric indices were measured and glucose, insulin, leptin and MCP-1 were measured in blood. IR was calculated. RESULTS: MCP-1 level was significantly higher in diabetics than non-diabetics irrespective of gender (p < 0.05). Irrespective of diabetes status, the serum leptin concentration was significantly higher (p < 0.05) in obese and females subjects than in non-obese and male subjects respectively. There were no significant correlations between IR and MCP-1 or leptin in all subgroups of subjects studied. General linear modelling analysis showed that only diabetes state significantly predicted MCP-1 levels (p < 0.05) whereas non of the factors predicted leptin levels (p > 0.05). CONCLUSION: Routine measurement of leptin and MCP-1 would be potentially useful in assessment of patients for the metabolic syndrome or coronary heart disease especially in black population.

Correlates of bone mineral density among postmenopausal women of African Caribbean ancestry: Tobago women's health study

Population dynamics predict a drastic growth in the number of older minority women, and resultant increases in the number of fractures. Low bone mineral density (BMD) is an important risk factor for fracture. Many studies have identified the lifestyle and health-related factors that correlate with BMD in Whites. Few studies have focused on non-Whites. The objective of the current analyses is to examine the lifestyle, anthropometric and health-related factors that are correlated with BMD in a population based cohort of Caribbean women of West African ancestry. We enrolled 340 postmenopausal women residing on the Caribbean Island of Tobago. Participants completed a questionnaire and had anthropometric measures taken. Hip BMD was measured by DXA. We estimated volumetric BMD by calculating bone mineral apparent density (BMAD). BMD was >10% and >25% higher across all age groups in Tobagonian women compared to US non-Hispanic Black and White women, respectively. In multiple linear regression models, 35-36% of the variability in femoral neck and total hip BMD respectively was predicted. Each 16-kg (one standard deviation (SD)) increase in weight was associated with 5% higher BMD; and weight explained over 10% of the variability of BMD. Each 8-year (1 SD) increase in age was associated with 5% lower BMD. Current use of both thiazide diuretics and oral hypoglycemic medication were associated with 4-5% higher BMD. For femoral neck BMAD, 26% of the variability was explained by a multiple linear regression model. Current statin use was associated with 5% higher BMAD and a history of breast feeding or coronary heart disease was associated with 1-1.5% of higher BMAD. In conclusion, African Caribbean women have the highest BMD on a population level reported to date for women. This may reflect low European admixture. Correlates of BMD among Caribbean women of West African ancestry were similar to those reported for U.S. Black and White women.

Adipose tissue infiltration in skeletal muscle: age patterns and association with diabetes among men of African ancestry

BACKGROUND: Although obesity is strongly associated with diabetes, the greater prevalence of diabetes in persons of African ancestry than in those of other ancestries cannot be explained simply by differences in total or central adiposity. OBJECTIVE: We examined whether skeletal muscle composition is associated with diabetes in 1249 men of African ancestry aged >or=40 y. DESIGN: Anthropometry and fasting serum glucose were measured, and lower-leg skeletal muscle composition was assessed with peripheral quantitative computerized tomography (pQCT). RESULTS: The prevalence of diabetes in this population was high (21%). We observed an age-associated adipose tissue remodeling in skeletal muscle and greater intermuscular (IMAT) and lesser subcutaneous (SAT) adipose tissue area with advancing age (P < 0.0001). Multivariate stepwise logistic regression identified more IMAT and less SAT to be significantly associated with a greater prevalence of diabetes. Even among normal-weight men [body mass index (BMI; in kg/m(2)) < 25], diabetic men had significantly (P = 0.01) more IMAT than did those without diabetes. Greater IMAT was also associated with a greater prevalence of hyperglycemia in men with a family history of diabetes than in those without such history (P for interaction = 0.02). CONCLUSIONS: These findings underscore the independent associations of subcutaneous and intermuscular fat among men of African ancestry, an effect that may be modified by a family history of diabetes. Further studies are needed to identify the genetic and physiologic mechanisms that influence the distribution and remodeling of adipose tissue in skeletal muscle with aging.'

Genetic and environmental influences on skeletal muscle phenotypes as a function of age and sex in large, multigenerational families of African heritage

The aim of this study was to estimate the heritability of and environmental contributions to skeletal muscle phenotypes (appendicular lean mass and calf muscle cross-sectional area) in subjects of African descent and to determine whether heritability estimates are impacted by sex or age. Body composition was measured by dual-energy X-ray absorptiometry and computed tomography in 444 men and women aged 18 yr and older (mean: 43 yr) from eight large, multigenerational Afro-Caribbean families (family size range: 21-112). Using quantitative genetic methods, we estimated heritability and the association of anthropometric, lifestyle, and medical variables with skeletal muscle phenotypes. In the overall group, we estimated the heritability of lean mass and calf muscle cross-sectional area (h(2) = 0.18-0.23, P < 0.01) and contribution of environmental factors to these phenotypes (r(2) = 0.27-0.55, P < 0.05). In our age-specific analysis, the heritability of leg lean mass was lower in older vs. younger individuals (h(2) = 0.05 vs. 0.23, respectively, P = 0.1). Sex was a significant covariate in our models (P < 0.001), although sex-specific differences in heritability varied depending on the lean mass phenotype analyzed. High genetic correlations (rho(G) = 0.69-0.81; P < 0.01) between different lean mass measures suggest these traits share a large proportion of genetic components. Our results demonstrate the heritability of skeletal muscle traits in individuals of African heritage and that heritability may differ as a function of sex and age. As the loss of skeletal muscle mass is related to metabolic abnormalities, disability, and mortality in older individuals, further research is warranted to identify specific genetic loci that contribute to these traits in general and in a sex- and age-specific manner.

Cardiorespiratory fitness, all-cause mortality, and risk of cardiovascular disease in Trinidadian men--the St James survey

BACKGROUND: This study examined whether cardiorespiratory fitness is a risk factor for cardiovascular disease, myocardial infarction, and all-cause mortality in a low- to middle-income Trinidadian community of African, South Asian Indian, and European origin. Those of Indian descent have a distinctively high rate of myocardial infarction. METHODS: The St James Study is a prospective total community survey located in Port-of-Spain, Trinidad, West Indies. A random sample of 626 men aged 35-69 years, without angina of effort, previous myocardial infarction, partial or complete atrio-ventricular conduction defect, complete heart block, or exercise-induced asthma, was used for the assessment of cardiorespiratory fitness by cycle ergometry. Surveillance for morbidity and mortality was maintained for an average of 7.3 years. RESULTS: When the subjects were grouped into those with an age- and fat-free mass-adjusted peak oxygen uptake above and below the mean of 60.4 mmol/min (1.34 l/min), the hazard ratios (below/above) (95% confidence interval) for all-cause mortality, cardiovascular disease incidence, and incidence of myocardial infarction, after allowance for conventional cardiovascular risk factors, were 2.08 (1.23-3.52), 2.13 (1.22-3.69), and 2.36 (0.84-6.67), respectively. For those unable to achieve a level of work requiring an oxygen uptake of 67 mmol/min (1.5 l/min) during progressive exercise, the respective hazard ratios were 3.49 (1.57-7.76), 2.29 (1.21-4.33), and 5.45 (1.22-24.34). Indian ethnicity remained a predictor of myocardial infarction after allowance for cardiorespiratory performance. CONCLUSION: Low cardiorespiratory fitness is a risk factor for cardiovascular disease morbidity and mortality in the low- to middle-income developing community of Trinidad.

Estimates of African, European and Native American ancestry in Afro-Caribbean men on the island of Tobago

BACKGROUND/AIMS:The Tobago Afro-Caribbean population is a valuable resource for studying the genetics of diseases that show significant differences in prevalence between populations of African descent and populations of other ancestries. Empirical confirmation of low European and Native American admixture may help in clarifying the ethnic variation in risk for such diseases. We hypothesize that the degree of European and Native American admixture in the Tobago population is low.METHODS:Admixture was estimated in a random sample of 220 men, from a population-based prostate cancer screening survey of 3,082 Tobago males, aged 40 to 79 years. We used a set of six autosomal markers with large allele frequency differences between the major ethnic populations involved in the admixture process, Europeans, Native Americans and West Africans.RESULTS:The ancestral proportions of Tobago population are estimated as 94.0+/-1.2% African, 4.6+/-3.4% European and 1.4+/-3.6% Native American.CONCLUSIONS:We conclude that Tobago Afro-Caribbean men are predominantly of West African ancestry, with minimal European and Native American admixture. The Tobago population, thus, may carry a higher burden of high-risk alleles of African origin for certain diseases than the more admixed African-American population. Conversely, this population may benefit from a higher prevalence of protective alleles of African origin.

Pathways to care and ethnicity. 1: Sample characteristics and compulsory admission.

Background Many studies have found high levels of compulsory admission to psychiatric hospital in the UK among African–Caribbean and Black African patients with a psychotic illness. Aims To establish whether African–Caribbean and Black African ethnicity is associated with compulsory admission in an epidemiological sample of patients with a first episode of psychosis drawn from two UK centres. Method All patients with a firstepisode of psychosis who made contact with psychiatric services over a 2-year period and were living in defined areas were included in the (ÆSOP)study. For this analysis we included all White British, other White, African–Caribbean and Black African patients from the ÆSOP sampling frame. Clinical, socio-demographic and pathways to care data were collected frompatients, relatives and case notes. Results African–Caribbean patients were significantly more likely to be compulsorily admitted than White British patients, as were Black African patients. African–Caribbean men were the most likely to be compulsorily admitted. Conclusions These findings suggest that factors are operating at or prior to first presentation to increase the risk of compulsory admission among African–Caribbean and Black African patients.

Pathways to care and ethnicity. 2: Source of referral and help-seeking.

Background Previous research has found that African–Caribbean and Black African patients are likely to come into contact with mental health services via more negative routes, when compared with White patients. We soughtto investigate pathways to mental health care and ethnicityin a sample of patients with a first episode of psychosis drawn from two UK centres. Method We included all White British, other White, African–Caribbean and Black African patients with a first episode of psychosis who made contact with psychiatric services over a 2-year period and were living in defined areas. Clinical, socio-demographic and pathways to care data were collected from patients, relatives and case notes. Results Compared with White British patients, general practitioner referral was less frequent for both African–Caribbean and Black African patients and referral by a criminal justice agency was more common. With the exception of criminal justice referrals for Black African patients, these findings remained significant after adjusting for potential confounders. Conclusions These findings suggest that factors are operating during a first episode of psychosis to increase the risk that the pathway to care for Black patients will involve non-health professionals.

Reliability and validity of a short form household food security scale in a Caribbean community

BACKGROUND: We evaluated the reliability and validity of the short form household food security scale in a different setting from the one in which it was developed. METHODS: The scale was interview administered to 531 subjects from 286 households in north central Trinidad in Trinidad and Tobago, West Indies. We evaluated the six items by fitting item response theory models to estimate item thresholds, estimating agreement among respondents in the same households and estimating the slope index of income-related inequality (SII) after adjusting for age, sex and ethnicity. RESULTS: Item-score correlations ranged from 0.52 to 0.79 and Cronbach's alpha was 0.87. Item responses gave within-household correlation coefficients ranging from 0.70 to 0.78. Estimated item thresholds (standard errors) from the Rasch model ranged from -2.027 (0.063) for the 'balanced meal' item to 2.251 (0.116) for the 'hungry' item. The 'balanced meal' item had the lowest threshold in each ethnic group even though there was evidence of differential functioning for this item by ethnicity. Relative thresholds of other items were generally consistent with US data. Estimation of the SII, comparing those at the bottom with those at the top of the income scale, gave relative odds for an affirmative response of 3.77 (95% confidence interval 1.40 to 10.2) for the lowest severity item, and 20.8 (2.67 to 162.5) for highest severity item. Food insecurity was associated with reduced consumption of green vegetables after additionally adjusting for income and education (0.52, 0.28 to 0.96). CONCLUSIONS: The household food security scale gives reliable and valid responses in this setting. Differing relative item thresholds compared with US data do not require alteration to the cut-points for classification of 'food insecurity without hunger' or 'food insecurity with hunger'. The data provide further evidence that re-evaluation of the 'balanced meal' item is required.

Commentary: getting ahead of the childhood obesity curve

Comment on: Overweight, obesity and skinfold thicknesses of children of African or Indian descent in Trinidad and Tobago. Gulliford MC, Mahabir D, Rocke B, Chinn S, Rona R. Int J Epidemiol. 2001 Oct; 30(5):989-98.

Overweight, obesity and skinfold thicknesses of children of African or Indian descent in Trinidad and Tobago

BACKGROUND: To evaluate distribution of body mass index (BMI) and subcutaneous fat in children of African or Indian subcontinent descent living in Trinidad and Tobago. METHODS: A cross-sectional survey was carried out in a nationally representative sample of 66 government schools. Measurements were made of children's heights, weights, triceps and subscapular skinfold thicknesses. Data were analysed by sex and ethnic group and comparison was made with international standards for overweight and obesity and with British (1990) reference curves for BMI. RESULTS: Data were analysed for 5688/6731 (85%) eligible children including 1934 Afro-Trinidadian, 1689 Indo-Trinidadian, and 1794 of mixed ethnicity. Afro-Trinidadian and mixed children were taller, but Indo-Trinidadian children were shorter than reference. Values for BMI were lower than reference: mean standard deviation score (SDS), (95% confidence interval) Afro-Trinidadian -0.34 (-0.39 to -0.28), Indo-Trinidadian -1.32 (-1.39 to -1.25), mixed -0.67 (-0.74 to -0.61). Overall 486 (8.5%, 7.8 to 9.3%) of children were overweight and 138 (2.4%, 2.0 to 2.9%) were obese. Triceps skinfold thickness values were lower than reference (-0.45, -0.48 to -0.42 SDS) but subscapular skinfold thicknesses were higher (0.45, 0.43 to 0.47 SDS). Higher BMI were associated with higher BMI in the child's parents, higher reported birthweight, older age of the child's mother, smaller family size, and with higher maternal educational attainment. CONCLUSIONS: Overweight was prevalent and distribution of subcutaneous fat was central. Work is needed to determine whether these findings are associated with adult patterns of fat distribution and metabolic abnormalities.