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Biomedical subjects

T Forrester

Publications and source records attributed to T Forrester.

At least 19 recordsLinked to original sources
PubMed2006

Relationship between birth weight and urea kinetics in children.

OBJECTIVE: To explore the effect of birth weight on urea kinetics in young healthy children. DESIGN: Observational study. SETTING: Tertiary center for treatment of malnutrition. SUBJECTS: A total of 17 male children, 6-24 months old, who had recovered from malnutrition. INTERVENTIONS: Urea kinetics were measured using stable isotope methodology with [(15)N(15)N]-urea over 36 h. RESULTS: Birth weight was negatively related to urea hydrolysis after controlling for the intake of protein (adjusted R (2 ) = 0.91, P = 0.001) and separately for energy intake (adjusted R (2) = 0.95, P = 0.001), age (adjusted R (2) = 0.90, P = 0.001) and rate of weight gain (adjusted R (2) = 0.91, P = 0.001). There was a tendency for higher urea production in the children with lower birth weight after controlling for nitrogen intake (adjusted R (2) = 0.93, P = 0.099), and separately for age (adjusted R (2) = 0.94, P = 0.06) and rate of weight gain (adjusted (R (2) = 0.92, P = 0.096). Urea excretion was not significantly related to birth weight. CONCLUSIONS: The salvaging of urea nitrogen following urea hydrolysis contributed significantly more to the nitrogen economy in children with lower birth weight compared to those with higher birth weight. This may be as a result of reductive adaptation in the children with lower birth weight as a consequence of inappropriate prenatal nutrition and growth.

Adaptation, Physiological↗
PubMed2006

Anticardiolipin antibodies in Jamaican primiparae.

A prevalence survey of anticardiolipin antibodies (aCL) was done among 924 primiparae. aCL were measured in serum by the standardised anticardiolipin enzyme linked immunosorbent assays (ELISA) and beta(2)-glycoprotein 1 assays to determine the seroprevalence of both beta(2) glycoprotein 1 dependent aCL and beta(2)-glycoprotein 1 independent aCL in Jamaican primiparae, to determine whether aCL are associated with abnormal pregnancy outcomes and if treatment with aspirin had any effect on pregnancy outcome in aCL positive primiparae. The prevalence of aCL was (32/671) 4.8% (95%CI 3.2-6.4) in women who were tested twice. A total of 49 of 924 primiparae or 5.3% (95%CI 3.9-6.7) were positive for aCL on at least one occasion. Only three of the 32 primiparae 3/32 (9.4%) who were positive for aCL on two occasions were positive for beta(2)-glycoprotein 1 dependent aCL. Pregnancy outcome did not differ significantly with respect to aCL status. Aspirin therapy did not influence pregnancy outcome in the 49 aCL positive primiparae studied.

Adolescent↗
PubMed2005

A randomized trial on sodium reduction in two developing countries.

Hypertension remains the most common cardiovascular risk factor in developing countries, yet the majority of patients have no access to pharmacological therapy. Population-wide preventive strategies, such as salt restriction, are an attractive alternative, but experience in resource-poor settings is limited. To address this question, we conducted a randomized crossover study of salt restriction in adults living in Nigeria and Jamaica in order to estimate the mean blood pressure (BP) response. After a 4-week run-in period to determine willingness to adhere to a low-salt diet, 56 Jamaicans and 58 Nigerians completed an 8-week crossover study of low-salt and high-salt intake. Baseline BPs were in the normotensive range (systolic=125 mmHg in Jamaica, 114 mmHg in Nigeria). Baseline urinary sodium excretion was 86.8 and 125.6 mEq/day in Nigeria and Jamaica, respectively. The mean difference between urinary sodium excretion at baseline and at the end of the 3-week low-sodium phase was 33.6 mEq/day in Nigeria and 57.5 mEq/day in Jamaica. During the high-sodium phase, mean change in urinary sodium excretion from baseline to week 3 was 35.0 and 5.5 mEq/day in Nigeria and Jamaica, respectively. The mean change in systolic BP ('high' vs 'low' sodium phase) was approximately 5 mmHg in both groups. This study suggests that the efficacy of sodium reduction in developing countries equals those noted in more affluent cultures. If promoted on a wide scale, sodium reduction could be used to treat persons with established hypertension, and more importantly, to prevent age-related increases in BP in poor communities.

Adult↗
PubMed2005

Relationship between blood pressure and physical activity assessed with stable isotopes.

Intrapopulation and interpopulation variation in blood pressure (BP) often reflects the joint effect of a complex set of risk factors, including lifestyle factors such as physical activity, diet, smoking and alcohol use. In this study, we set out to quantify the impact of habitual levels of physical activity on BP within and between three populations at contrasting levels of population risk of hypertension. Individuals were randomly sampled from communities in Nigeria (n=57), Jamaica (from Kingston, n=35) and the United States (from the Chicago area, n=32). Activity energy expenditure (AEE) (estimated from resting energy expenditure measured by indirect calorimetry and total expenditure measured with doubly labelled water) was used as an objective estimate of physical activity. In each of the three samples, there was a consistent negative correlation between BP and AEE. This negative association persisted after adjustment for age, sex and body fat (body mass index or percent fat mass). In multivariate models, adiposity was no longer a significant predictor of BP after accounting for low AEE. In conclusion these data suggest that habitual levels of physical activity may have a generalizable relationship with BP in populations with widely different social and environmental characteristics.

Adult↗
PubMed2004

Fetal growth is directly related to maternal anthropometry and placental volume.

OBJECTIVE: To describe the influence of maternal weight and weight gain, placental volume and the rate of placental growth in early pregnancy on fetal dimensions measured sonographically. DESIGN: In a prospective study, 712 women were recruited from the antenatal clinic of the University Hospital of the West Indies. Data analysis was confined to 374 women on whom measurements of the placental volume at 14, 17 and 20 weeks gestation were complete. Measurements of maternal anthropometry and fetal size (by ultrasound) were performed. Weight gain in pregnancy between the first antenatal visit (8-10 weeks) and 20 weeks gestation, and the rate of growth of the placenta between 14-17 and 17-20 weeks gestation were calculated. MAIN OUTCOME MEASURES: Fetal anthropometry (abdominal and head circumferences, femoral length, and biparietal diameter) at 35 weeks gestation. RESULTS: Lower maternal weight at the first antenatal visit was associated with a significantly smaller placental volume at 17 and 20 weeks gestation (P<0.002 and <0.0001 respectively). In all women, maternal weight gain was directly related to fetal anthropometry. Placental volume at 14 weeks gestation and the rate of growth of the placenta between 17 and 20 weeks gestation were significantly related to all four fetal measurements. CONCLUSION: This study has provided evidence that both placental volume, and the rate of placental growth may influence fetal size. These effects are evident in the first half of pregnancy, and appear to be mediated through maternal weight and weight gain.

Adult↗
PubMed2004

Higher income is more strongly associated with obesity than with obesity-related metabolic disorders in Jamaican adults.

OBJECTIVE: This study compares how income is related to obesity vs two obesity-related cardiovascular disease (CVD) risk factors-diabetes and hypertension-in adults from Jamaica. DESIGN: A cross-sectional population-based survey was used. In total, 847 men and 1249 women aged 25-74 y were randomly recruited from a periurban area in 1993-1998. MEASUREMENTS: Trained interviewers measured anthropometry and blood pressure, obtained fasting blood and collected self-reported data on income and disease history. RESULTS: Income was strongly and positively associated with obesity in men. In women, obesity levels were high even among the very poor, and the income gradient was more moderate. Although obesity-and particularly central fatness-was strongly associated with diabetes and hypertension prevalence, income was not significantly related to these disorders. CONCLUSIONS: Future research in developing countries should independently explore associations between income and obesity vs obesity-related disorders, and identify factors that explain any disparities.

Adult↗
PubMed2003

Social and dietary determinants of body mass index of adult Jamaicans of African origin.

OBJECTIVES: To determine the relationships between body mass index (BMI) and diet, social and behavioural factors among adult Jamaicans of African origin. DESIGN: Cross-sectional. SETTING: Urban communities in Jamaica, West Indies. SUBJECTS: Three-hundred and sixty-three males and 561 females of African origin, aged 25-74 y. RESULTS: Women had higher mean BMIs (27.5+/-6.4 kg/m(2)) than men (23.4+/-4.3 kg/m(2)); 30.7% of women compared with 6.7% of men were obese. There was a tendency for obese men to have higher percentage of intakes from fat and less from carbohydrate, and women reported diets in which the percentage contribution of protein increased significantly with increasing BMI. In multivariate analyses, BMI was not explained by energy but was associated with protein intakes in females only. Predictors of relative weight were inversely related. Social (marital status) and behavioural (cigarette smoking) factors predicted BMI in both genders; older age in men and increased fibre intakes in women were associated with lower BMI. CONCLUSIONS: Social and behavioural factors are important determinants of body weight. Further investigations are needed which consider factors such as physical activity, genetic and other environmental variables as predictors of relative weight.

Adult↗
PubMed2002

Shortness at birth is associated with insulin resistance in pre-pubertal Jamaican children.

AIM: To investigate the relationship between anthropometry at birth and glucose/insulin metabolism in childhood using the response to an oral glucose challenge. METHOD: Four hundred mother/child pairs on whom gestational and birth data were available were studied. After an overnight fast, anthropometric measurements were made on the children and an oral glucose tolerance test performed. The plasma concentrations of insulin, pro-insulin and 32-33 split pro-insulin were also measured. Skinfold thicknesses were used to calculate percentage body fat and fat mass was derived from the percentage fat and absolute weight. RESULTS: The mean age of the children was 8 y (range 7.5-10.5), and six exhibited impaired glucose tolerance based on WHO criteria. Insulin concentration 120 min after the oral glucose load (a measure of insulin resistance) was inversely related to length at birth (P<0.005). The children who were in the shortest quartile at birth and were heaviest at 8 y old had the highest insulin concentration. CONCLUSION: Shortness at birth is related to insulin resistance. Such insensitivity to the action of insulin is greater in heavier children.

Blood Glucose↗
PubMed2001

Trans-ethnic fine mapping of a quantitative trait locus for circulating angiotensin I-converting enzyme (ACE).

Circulating angiotensin I-converting enzyme (ACE) levels are influenced by a major quantitative trait locus (QTL) that maps to the ACE gene. Phylogenetic and measured haplotype analyses have suggested that the ACE-linked QTL lies downstream of a putative ancestral breakpoint located near to position 6435. However, strong linkage disequilibrium between markers in the 3' portion of the gene has prevented further resolution of the QTL in Caucasian subjects. We have examined 10 ACE gene polymorphisms in Afro-Caribbean families recruited in JAMAICA: Variance components analyses showed strong evidence of linkage and association to circulating ACE levels. When the linkage results were contrasted with those from a set of British Caucasian families, there was no evidence for heterogeneity between the samples. However, patterns of allelic association between the markers and circulating ACE levels differed significantly in the two data sets. In the British families, three markers [G2215A, Alu insertion/deletion and G2350A] were in complete disequilibrium with the ACE-linked QTL. In the Jamaican families, only marker G2350A showed strong but incomplete disequilibrium with the ACE-linked QTL. These results suggest that additional unobserved polymorphisms have an effect on circulating ACE levels in Jamaican families. Furthermore, our results show that a variance components approach combined with structured, quantitative comparisons between families from different ethnic groups may be a useful strategy for helping to determine which, if any, variants in a small genomic region directly influence a quantitative trait.

Black People↗
PubMed2001

Heritability of obesity-related traits among Nigerians, Jamaicans and US black people.

OBJECTIVE: The mean values for anthropometric traits vary across population groups and this variation is clearly determined for the most part by the environment. The familiarity of anthropometric traits also varies in reports from different populations, although this variation has not been shown to follow a consistent pattern. To examine whether heritability is influenced by socio-cultural factors, we conducted a cross-cultural study of populations of the African diaspora. PARTICIPANTS: Data were collected on 1868 family members from Nigeria, 623 from Jamaica and 2132 from metropolitan Chicago, IL, USA. MEASUREMENTS: Height and weight were measured and body mass index (kg/m(2)) calculated. Fat-free mass, fat mass and percentage body fat were estimated using bioelectrical impedance analysis. Plasma leptin concentrations were also measured. The proportion of variance attributable to additive genetic and non-shared environmental components was estimated with the maximum likelihood variance decomposition method. RESULTS: Mean values for all anthropometric traits increased along the socio-cultural gradient, and obesity increased from 5% in Nigeria to 23% in Jamaica and 39% in the USA. Within populations the relationships among traits both within individuals and within families were highly consistent. Heritability estimates for weight, body mass index, fat mass and percentage body fat were approximately 50% for all groups. Heritability for height was lower in Nigeria (62%) than in Jamaica (74%) or the US (87%). CONCLUSION: The familial patterns of body size and energy storage appear to be consistent in these genetically related populations across a wide range of environmental conditions.

Adult↗
PubMed2001

Habitual diet in four populations of African origin: a descriptive paper on nutrient intakes in rural and urban Cameroon, Jamaica and Caribbean migrants in Britain.

BACKGROUND: The prevalence of chronic diseases is increasing in West Africa, the Caribbean and its migrants to Britain. This trend may be due to the transition in the habitual diet, with increasing (saturated) fat and decreasing fruit and vegetable intakes, both within and between countries. OBJECTIVE: We have tested this hypothesis by comparing habitual diet in four African-origin populations with a similar genetic background at different stages in this transition. DESIGN: The study populations included subjects from rural Cameroon urban Cameroon Jamaica and African-Caribbeans in Manchester, UK all aged 25-74 years. Habitual diet was assessed by a food-frequency questionnaire, specifically developed for each country separately. RESULTS: Total energy intake was greatest in rural Cameroon and lowest in Manchester for all age/sex groups. A tendency towards the same pattern was seen for carbohydrates, protein and total fat intake. Saturated and polyunsaturated fat intake and alcohol intake were highest in rural Cameroon, and lowest in Jamaica, with the intakes in the UK lower than those in urban Cameroon. The percentage of energy from total fat was higher in rural and urban Cameroon than in Jamaica and the UK for all age/sex groups. The opposite was seen for percentage of energy from carbohydrate intake, the intake being highest in Jamaica and lowest in rural Cameroon. The percentage of energy from protein increased gradually from rural Cameroon to the UK. CONCLUSIONS: These results do not support our hypothesis that carbohydrate intake increased, while (saturated) fat intake decreased, from rural Cameroon to the UK.

Adult↗
PubMed2001

Reproducibility and validity of a quantitative food-frequency questionnaire among Jamaicans of African origin.

BACKGROUND: An interviewer-administered quantitative food-frequency questionnaire (FFQ) was developed to determine the energy and nutrient intakes of adult Jamaicans of African origin as part of a study of the epidemiology of diabetes and hypertension. METHODS: Reproducibility of the questionnaire was investigated in 123 participants aged 25-74 years. The relative validity of the FFQ was assessed against twelve 24-hour recalls administered over 12 months in 73 of the participants. In addition, energy intakes (EI) were compared with estimated basal metabolic rates (BMR). RESULTS: Reproducibility correlation coefficients (Pearson and intraclass) varied between 0.42 for retinol and 0.71 for carbohydrate, with most values falling between 0.50 and 0.60. When compared with repeated 24-hour recalls, the FFQ estimated slightly higher energy (mean 6%) and macronutrient intakes (mean 2-14%), and was within 5% when expressed as a percentage of energy intake. Micronutrients were higher by 1.19 (calcium) to 1.61 times (vitamin C). Unadjusted correlations between the FFQ and the reference method ranged from 0.20 for beta-carotene to 0.86 for alcohol. Cross-classification of nutrients into quartiles showed that 46-48% of participants in the lowest and highest quartiles were jointly classified by both methods. Misclassifications were low for most nutrients with one or two persons misclassified at the extreme quartiles. EI/BMR ratios suggested light to moderate activity levels appropriate for an urban population in a developing country. CONCLUSIONS: The FFQ showed reasonable reproducibility and validity and is suitable for estimating the habitual intakes of energy and macronutrients, but was poor for some micronutrients (retinol and beta-carotene).

Adult↗
PubMed2001

Sick genes, sick individuals or sick populations with chronic disease? The emergence of diabetes and high blood pressure in African-origin populations.

AIM AND METHODS: To discuss evidence for and against genetic 'causes' of type 2 diabetes, illustrated by standardized study of glucose intolerance and high blood pressure in four representative African origin populations. Comparison of two genetically closer sites: rural (site 1) and urban Cameroon (2); then Jamaica (3) and Caribbean migrants to Britain (80% from Jamaica-4). BACKGROUND: Alternatives to the reductionist search for genetic 'causes' of chronic disease include Rose's concept that populations give rise to 'sick' individuals. Twin studies offer little support to genetic hypotheses because monozygotic twins share more than genes in utero and suffer from ascertainment bias. Non-genetic intergenerational mechanisms include amniotic fluid growth factors and maternal exposures. Type 2 diabetes and hypertension incidence accelerate in low-risk European populations from body mass > or =23 kg/m2, well within 'desirable' limits. Transition from subsistence agriculture in West Africa occurred this century and from western hemisphere slavery only six generations ago, with slow escape from intergenerational poverty since. RESULTS: 'Caseness' increased clearly within and between genetically similar populations: age-adjusted diabetes rates were 0.8, 2.4, 8.5 and 16.4% for sites 1-4, respectively; for 'hypertension', rates were 7, 16, 21 and 34%, with small shifts in risk factors. Body mass index rose similarly. CONCLUSION: Energy imbalance and intergenerational socioeconomic influences are much more likely causes of diabetes (and most chronic disease) than ethnic/genetic variation, which does occur, poorly related to phenotype. The newer method of 'proteomics' holds promise for identifying environmental triggers influencing gene products. Even in lower prevalence 'westernized' societies, genetic screening per se for diabetes/chronic disease is likely to be imprecise and inefficient hence unreliable and expensive.

Black People↗
PubMed2001

Hypertension in four African-origin populations: current 'Rule of Halves', quality of blood pressure control and attributable risk of cardiovascular disease.

OBJECTIVE: To assess the public health burden from high blood pressure and the current status of its detection and management in four African-origin populations at emerging or high cardiovascular risk. DESIGN: Cross-site comparison using standardized measurement and techniques. SETTING: Rural and urban Cameroon; Jamaica; Manchester, Britain. SUBJECTS: Representative population samples in each setting. African-Caribbeans (80% of Jamaican origin) and a local European sample in Manchester. MAIN OUTCOME MEASURES: Cross-site age-adjusted prevalence; population attributable risk. RESULTS: Among 1,587 men and 2,087 women, age-adjusted rates of blood pressure > or =160 or 95 mmHg or its treatment rose from 5% in rural to 17% in urban Cameroon, despite young mean ages, to 21% in Jamaica and 29% in Caribbeans in Britain. Treatment rates reached 34% in urban Cameroon, and 69% in Jamaican- and British-Caribbean-origin women. Sub-optimal blood pressure control (> 140 and 90 mmHg) on treatment reached 88% in European women. Population attributable risks (or fractions) indicated that up to 22% of premature all-cause, and 45% of stroke mortality could be reduced by appropriate detection and treatment. Additional benefit on just strokes occurring on treatment could be up to 47% (e.g. in both urban Cameroon men and European women) from tighter blood pressure control on therapy. Cheap, effective therapy is available. CONCLUSION: With mortality risk now higher from non-communicable than communicable diseases in sub-Saharan Africa and elsewhere, systematic measurement, detection and genuine control of hypertension once treated can go hand-in-hand with other adult health programmes in primary care. Cost implications are not great. The data from this collaborative study suggest that such efforts should be well rewarded.

Adult↗
PubMed2001

Anticardiolipin antibodies and risk of thromboembolic disease in young Jamaican women.

BACKGROUND: Anticardiolipin antibodies (aCL) are a heterogeneous group of antiphospholipid antibodies that are associated with arterial and venous thrombosis. We measured aCL in women, aged 15-49 years, to determine if they are an independent risk factor for thromboembolic disease. STUDY DESIGN: Case--control study METHODS: Fifty cases were studied including venous thromboembolism (n=29), stroke and myocardial infarction (n=21), along with 148 age-matched controls. Serum samples were assayed for aCL and anti-beta2 glycoprotein 1 antibodies using the enzyme-linked immunosorbent assay (ELISA). Information on other risk factors was obtained by a standardized questionnaire. RESULTS: aCL were present in 16/50 (32%) of cases compared with 25/148 (17%) of controls (P[?]=[?]0.02). Unadjusted odds ratio (OR) and 95% confidence interval (95% CI) for thromboembolic disease associated with aCL was 2.32 (1.10--4.87). Other risk factors were hypertension, 2.93 (1.20--7.17) and a history of other heart diseases, 12.78 (1.32--123.60). Adjustment for hypertension, diabetes, oral contraceptive use, smoking, alcohol use, varicose veins, a family history of cardiovascular disease and a history of other heart diseases yielded OR (95%CI) 2.99 (1.32--6.80). beta2 glycoprotein 1-dependent aCL were also an independent risk factor, OR 4.56 (1.76--17.83). Subgroup analysis was carried out separately for cases of MI and stroke and for venous thrombosis. Adjusted OR (95% CI) associated with aCL in cases of MI and stroke was 1.76 (0.46--6.73) and 3.32 (1.15--9.54) for venous thromboembolism. CONCLUSION: aCL are a risk factor for thromboembolic disease in young Jamaican women. They confer a strong independent risk for venous thromboembolism.

Adolescent↗
PubMed2000

Localization of a small genomic region associated with elevated ACE.

Defining the relationship between multiple polymorphisms in a small genomic region and an underlying quantitative trait locus (QTL) represents a major challenge in human genetics. Pedigree analyses have shown that angiotensin I-converting enzyme (ACE) levels are influenced by a QTL located within or close to the ACE gene and most likely resides in the 3' region of this locus. We genotyped seven polymorphisms spanning 13 kb in the 3' end of ACE in 159 Afro-Caribbean subjects to evaluate the linkage disequilibrium between these sites and to narrow the genomic region associated with an elevated ACE level using a cladistic analysis. The linkage disequilibrium measurement D' and a haplotype tree revealed three distinct haplotype segments, presumably because of recombination. The value of the linkage disequilibrium parameter p(excess) was highest for site 22982, which is located in the middle segment. A series of nested, cladistic analyses confirmed that the other two regions are unlikely to be the ACE-linked QTL and that the variant resides in the middle region. Analyses of the same polymorphisms in 98 unrelated Europeans in the Monitoring Trends and Determinants in Cardiovascular Diseases (MONICA) study resulted in fewer haplotypes than were observed among the Afro-Caribbean subjects, suggesting that populations with greater genetic diversity may be especially informative for fine-scale mapping.

Black People↗
PubMed2000

Underreporting of energy intake in four populations of African origin.

OBJECTIVE: To investigate the frequency of dietary underreporting in four African populations in different geographic and cultural settings. SUBJECTS: Seven-hundred and forty three men and women from rural Cameroon, 1042 men and women from urban Cameroon, 857 men and women from Jamaica and 243 male and female African Caribbeans from the UK. Subjects who reported dieting or weight control were excluded. MEASUREMENTS: Habitual dietary intake was estimated with a quantitative food frequency questionnaire, developed specifically for each country. Underreporting was defined using three cut-off levels for energy intake/estimated basic metabolic rate (EI/BMRest), based on age, sex and weight, in each site. RESULTS: The EI/BMRest was highest in rural Cameroonian men at 3.07 (95% confidence interval: 2.97, 3.17) and women at 2.84 (2.74, 2.94), intermediate in urban Cameroon and Jamaica and lowest in the UK men and women at 1.44 (1.26, 1.62) and 1.41 (1.21, 1.61). This trend existed even after adjustment for age, BMI and education (P for trend<0.0001). The trend in the frequency of underreporting using the lowest cut-off level for EI/BMRest of 1.15 was 6% and 6% in rural Cameroon for women and men, respectively, 4% and 5% in urban Cameroon, 24% and 19% in Jamaica and 28% and 39% in the UK. With higher cut off levels this trend was similar. CONCLUSION: The results suggest that the frequency of dietary underreporting differs between societies and that Westernization may be one of the factors underlying this phenomenon.

Adult↗