Michael S. Boyne

Growth, body composition, and the onset of puberty: longitudinal observations in Afro-Caribbean children

CONTEXT Childhood growth and body composition may influence the onset of puberty. OBJECTIVE We examined the effects of birth size, growth rates throughout childhood, and body composition on the onset of puberty in Afro-Caribbean children. DESIGN AND SETTING This was a longitudinal birth cohort study (the Vulnerable Windows Cohort Study) in Jamaica. SUBJECTS AND MEASUREMENTS The anthropometry (weight, height, skinfold measurements, and waist circumference) of 259 children was measured at birth, at 6 wk, every 3 months to 2 yr, and then every 6 months. Tanner staging for puberty and orchidometry were performed every 6 months starting at approximately age 8 yr. Bioelectrical impedance was done at age 11 yr. RESULTS In the girls, thelarche, pubarche, and menarche occurred at median ages of 8.8, 9.9, and 12.0 yr, respectively. Pubarche in boys occurred at a median age of 11.3 yr when the median testicular volume was 2.8 ml. Faster weight gain during infancy (age 0-6 months) and childhood, but not birth size, was associated with more advanced puberty (P values <0.05). Fat mass at age 8 yr was associated with more advanced puberty (P values <0.001) in both sexes. At age 11 yr, lean mass, but not fat mass, was associated with more advanced puberty (P values <0.001). CONCLUSION These data support the hypothesis that faster growth throughout childhood, especially with fat mass accretion, is associated with more advanced puberty apart from menarche. With the onset of puberty, lean mass accretion significantly increases.

The transfer of 15N from urea to lysine in the human infant.

To explore the nutritional significance of urea hydrolysis for human subjects, male infants being treated for severe undernutrition were given oral doses of 10 mg [15N15N]urea every 3 h for 36 h, on admission, during rapid growth and after repletion with either moderate or generous intakes of protein. Urea hydrolysis was calculated from the 15N enrichment of urinary urea, and where possible, lysine, alanine, glycine and histidine were isolated from urine by preparative ion-exchange chromatography for measurement of 15N enrichment. Sufficient N was obtained for 15N enrichment of lysine to be measured on fifteen occasions from six children. Urea hydrolysis accounted for half of all urea production with 130 (SD 85) mg N/kg hydrolysed per d, most of which appeared to be utilized in synthetic pathways. Of the samples analysed successfully, nine samples of lysine were enriched with 15N (mean atom percent excess 0.0102, range 0.0017-0.0208) with relative enrichment ratios with respect to lysine of 1.63 (range 0.18-3.15), 1.96 (range 0.7-3.73) and 0.9 (range 0.4-1.8) for glycine, alanine and histidine respectively. Enriched samples were identified at each treatment phase and 68% of the variation in lysine enrichment was explained by the variation in urea enrichment with 54% explained by the overall rate of delivery of 15N to the lower gastrointestinal tract. The results indicate a minimum of 4.7 mg lysine per kg body weight made available by de novo synthesis with the more likely value an order of magnitude higher. Thus, urea hydrolysis can improve the quality of the dietary protein supply by enabling an increased supply of lysine and other indispensable amino acids.

Rapid increases in obesity in Jamaica, compared to Nigeria and the United States

BackgroundWeight gain in adulthood is now common in many populations, ranging from modest gains in developing countries to a substantial percentage of body weight in some Western societies. To examine the rate of change across the spectrum of low to high-income countries we compared rates of weight change in samples drawn from three countries, Nigeria, Jamaica and the United States.MethodsPopulation samples from Nigeria (n = 1,242), Jamaica (n = 1,409), and the US (n = 809) were selected during the period 1995–1999 in adults over the age of 19; participation rates in the original survey were 96%, 60%, and 60%, respectively. Weight in (kg) was measured on 3 different occasions, ending in 2005. Multi-level regression models were used to estimate weight change over time and pattern-mixture models were applied to assess the potential effect of missing data on estimates of the model parameters.ResultsThe unadjusted weight gain rate (standard error) was 0.34(0.06), 1.26(0.12), 0.34(0.19) kg/year among men and 0.43(0.06), 1.28(0.10), 0.40(0.15) kg/year among women in Nigeria, Jamaica, US, respectively. Regression-adjusted weight change rates were significantly different across country, sex, and baseline BMI. Adjusted weight gain in Nigeria, Jamaica and US was 0.31(0.05), 1.37(.04), and 0.52(0.05) kg/year respectively. Women in Nigeria and the US had higher weight gains than men, with the converse observed among Jamaicans. The obese experienced weight loss across all three samples, whereas the normal weight (BMI < 25) had significant weight gains. Missing data patterns had an effect on the rates of weight change.ConclusionWeight change in sample cohorts from a middle-income country was greater than in cohorts from either of the low- or high-income countries. The steep trajectory of weight gain in Jamaica, relative to Nigeria and the US, is most likely attributable to the accelerating effects of the cultural and behavioral shifts which have come to bear on transitional societies.

Impact of adiponectin and ghrelin on incident glucose intolerance and on weight change

Objectives  Adiponectin and ghrelin are associated with adiposity and type 2 diabetes in several studies. We sought to prospectively determine the interaction of adiponectin and ghrelin in the development of adiposity and hyperglycaemia.

The association of hypothalamic-pituitary-adrenal axis activity and blood pressure in an Afro-Caribbean population

Hyperactivity of the hypothalamic-pituitary-adrenal axis (HPAA) resulting from fetal programming may play a role in the development of high blood pressure (BP) in black people. We assessed the diurnal salivary cortisol profile in children with and without increased BP and evaluated their mothers HPAA. In a cross-sectional study, 20 Afro-Caribbean children (mean age 9.6 years) with higher blood pressures and 20 children with lower blood pressures were chosen from a prospective study of 569 mothers and children in Jamaica. Daytime salivary cortisol profiles were collected in the children and their mothers. The mothers were also assessed for features of the metabolic syndrome. Children with higher BP had higher mean morning salivary cortisol concentrations than those with lower BP (7.9 S.D. 1.9 vs. 4.5 S.D. 2.4nmol/l; p=0.03). Their mothers also had increased morning salivary cortisol concentrations (9.9 S.D. 1.8 vs. 5.5 S.D. 2.5nmol/l; p=0.02), but no changes in fasting glucose, insulin, lipids, BP or adiposity. Maternal and offspring cortisol concentrations correlated significantly (r=0.465, p=0.004). Maternal cortisol concentrations were significantly associated with the childs BP. We conclude that Afro-Caribbean children with higher BP have higher morning salivary cortisol concentrations. The childrens cortisol concentrations correlate significantly with the mothers cortisol concentrations. These findings suggest that the HPAA may play a role in the development of raised BP in Afro-Caribbean people.

Developmental origins of cardiovascular risk in Jamaican children: The Vulnerable Windows Cohort Study

Both intra-uterine and early childhood development contribute to the risk of developing CVD in adult life. We therefore evaluated the maternal, placental, fetal, birth, infant and childhood determinants of cardiovascular risk in a cohort of Afro-Jamaican children. The Vulnerable Windows Cohort is a longitudinal survey of 569 mothers and their offspring recruited from the first trimester. The offsprings anthropometry was measured at birth, at 6 weeks, every 3 months to 1 year and then every 6 months. At mean age 11.5 years, fasting blood was sampled for glucose, insulin and lipids. Analyses were confined to 296 women and their offspring who had complete data. Waist circumference (WC) was related to maternal weight and BMI, placental weight and to the size of the offspring in utero, at birth and the rate of growth in childhood (P < 0.05). Total cholesterol, TAG and glucose concentrations were unrelated to maternal, placental, fetal, neonatal and childhood measurements. Fasting insulin and homeostasis model assessment of insulin resistance were related to maternal weight and BMI (P < 0.05), but not after adjusting for WC. HDL-cholesterol was inversely related to placental and birth weight, and inversely related to weight and BMI throughout childhood (P < 0.001), but not after adjusting for WC. Systolic blood pressure was directly related to maternal weight, childs height, weight and BMI (P < 0.05), but not after adjustment for WC. Systolic blood pressure and fasting glucose concentration were inversely related to birth weight in boys but directly associated in girls. We concluded that maternal anthropometry during pregnancy, fetal size, and childhood growth rate contribute to cardiovascular risk factors in childhood.

Diabetes in the Caribbean: Trouble in paradise

Abstract Background : Many developing countries, including countries of the English-speaking Caribbean, are undergoing an epidemiologic transition and experiencing rapid increases in the prevalence of diabetes. Objectives : This article examines the epidemiology of diabetes, the types of diabetes, the etiologic factors and complications of diabetes, and the public health burden associated with diabetes in the Caribbean. Methods : An extensive PubMed literature search was conducted for the period 1951 to 2008 using the search terms diabetes, glucose intolerance, Caribbean, Jamaica, Barbados, Trinidad, Bahamas, Guyana, and the names of all the other English-speaking Caribbean countries. Results : Four hundred articles were identified in the literature search. Of these, 131 original articles were selected for inclusion in this review. Prevalence rates for diabetes ranged from 11% to 18% of the population in several countries. The prevalence of atypical diabetes (ketosis-prone diabetes) may be declining because of increases in the proportions of the population with type 2 diabetes mellitus. Ecologic studies show an east-to-west gradient from West Africa to the Caribbean for obesity and obesity-related diseases. The steep increase in the prevalence of obesity and the increase in sedentarism in Caribbean societies are the main risk factors driving the diabetes epidemic. The roles of early-life origins (specifically, in infants with low birth weight and rapid catch-up growth and/or macrosomic infants) and genetic factors await further clarification in this population. Diabetic foot, nephropathy, and stroke are common complications. Conclusions : In the English-speaking Caribbean, diabetes is a major public health burden that threatens the gross domestic product of these developing island nations. Macroeconomic initiatives are needed to start the combat against diabetes.

Sex-differences in adiponectin levels and body fat distribution: Longitudinal observations in Afro-Jamaicans §

We longitudinally explored the relationship of body size and adiponectin levels in 393 community-dwelling Afro-Jamaicans. Adiponectin levels were greater in women, increased with age and declined with abdominal adiposity. Multivariate regression analyses suggest that subcutaneous fat in women may contribute significantly to the variance in their adiponectin levels.

Impaired Cardiovascular Structure and Function in Adult Survivors of Severe Acute Malnutrition

Malnutrition below 5 years remains a global health issue. Severe acute malnutrition (SAM) presents in childhood as oedematous (kwashiorkor) or nonoedematous (marasmic) forms, with unknown long-term cardiovascular consequences. We hypothesized that cardiovascular structure and function would be poorer in SAM survivors than unexposed controls. We studied 116 adult SAM survivors, 54 after marasmus, 62 kwashiorkor, and 45 age/sex/body mass index–matched community controls who had standardized anthropometry, blood pressure, echocardiography, and arterial tonometry performed. Left ventricular indices and outflow tract diameter, carotid parameters, and pulse wave velocity were measured, with systemic vascular resistance calculated. All were expressed as SD scores. Mean (SD) age was 28.8±7.8 years (55% men). Adjusting for age, sex, height, and weight, SAM survivors had mean (SE) reductions for left ventricular outflow tract diameter of 0.67 (0.16; P<0.001), stroke volume 0.44 (0.17; P=0.009), cardiac output 0.5 (0.16; P=0.001), and pulse wave velocity 0.32 (0.15; P=0.03) compared with controls but higher diastolic blood pressures (by 4.3; 1.2–7.3 mm Hg; P=0.007). Systemic vascular resistance was higher in marasmus and kwashiorkor survivors (30.2 [1.2] and 30.8 [1.1], respectively) than controls 25.3 (0.8), overall difference 5.5 (95% confidence interval, 2.8–8.4 mm Hg min/L; P<0.0001). No evidence of large vessel or cardiac remodeling was found, except closer relationships between these indices in former marasmic survivors. Other parameters did not differ between SAM survivor groups. We conclude that adult SAM survivors had smaller outflow tracts and cardiac output when compared with controls, yet markedly elevated peripheral resistance. Malnutrition survivors are thus likely to develop excess hypertension in later life, especially when exposed to obesity.

A preliminary report on an assessment of a community-based intervention for diabetes control in adults with type 2 diabetes

OBJECTIVE The aim of this study was to evaluate the effectiveness of lay diabetes facilitators (LDFs) to increase knowledge and improve control among persons with diabetes. Methodology. A prospective cohort study was conducted among persons with diabetes in 16 health care centres in Jamaica to evaluate the effect of LDFs on glycaemia [haemoglobin A1c (HbA1c)] and body mass index (BMI). One hundred and fifty-nine persons with diabetes were recruited for the intervention from eight clinical settings in which LDFs had been recruited and trained. A matched group of 159 were recruited as a comparison sample from eight clinical settings without LDFs. HbA1c and BMI were measured at baseline and 6 months. RESULTS Mean HbA1c at baseline for the intervention and comparison groups were 7.9% and 8%, respectively. After 6 months, the intervention group showed a mean decrease of 0.6% while the comparison group showed an increase of 0.6%, significant after control for potential confounders (P < 0.05). There was no statistically significant change in BMI between groups. CONCLUSION Patients educated by LDFs showed improved metabolic control over the first 6 months of observation.