Biomedical subjects

Terrence Forrester

Publications and source records attributed to Terrence Forrester.

29 records · Page 2Linked to original sources

PubMed2004

Association between blood pressure and resting energy expenditure independent of body size.

Obesity is an important risk factor for hypertension; however, the pathway through which it raises blood pressure (BP) is poorly understood. Body size is also the primary determinant of energy expenditure, and we therefore examined the joint relationship of energy expenditure and body size to blood pressure. Resting energy expenditure (REE) was measured using respiratory gas exchange in population-based samples of 997 Nigerians and 452 African Americans. In a third sample of 118 individuals, nonresting energy expenditure (ie, physical activity) was measured in addition to REE. The univariate correlation between REE and BP ranged from 0.10 to 0.22 in the 3 samples (P<0.001). In multivariate models, adiposity, whether defined by body mass, fat mass, or leptin, was no longer associated with BP, while REE remained highly significant (P<0.001). The REE-BP association also persisted after adjustment for physical activity measured with doubly labeled water. The odds ratio for hypertension among persons in the highest quartile versus the lowest quartile of REE, after adjustment for body size, was 1.7. This relationship was not the result of hypertension among the obese, because it did not vary across the range of BMI and was the same in lean Nigerians as in obese Americans. These data suggest that metabolic processes represented by REE may mediate the effect of body size on BP. The interrelationship of REE with sympathetic tone, transmembrane ion exchange, or other metabolic processes that determine energy costs at rest could provide physiological explanations for this observation.

Adult↗

PubMed2004

Angiotensin I-converting enzyme polymorphisms, ACE level and blood pressure among Nigerians, Jamaicans and African-Americans.

The genes in the renin-angiotensin system are important physiologic candidates in studies of the genetic susceptibility to hypertension. Limited information has been available in most studies on the extent of variation in the candidate loci or the modifying effects of different environmental settings. We consequently genotyped 13 polymorphisms at the angiotensin I-converting enzyme (ACE) locus at an average distance of 2 kb in 2776 family members from Nigeria, Jamaica and an African-American community in the US. Allele and haplotype frequencies were similar in the three populations, with modest evidence of European admixture in the US. Two markers were consistently associated with ACE level in the three samples and the proportion of variance accounted for by ACE8 was similar in the three groups. No evidence of consistent association of single markers was noted with blood pressure across the three population samples, however. Likewise, in a haplotype-based analysis, despite significant associations within each population, the findings were not replicated consistently across all three samples. We did observe, however, that the overtransmitted haplotypes among hypertensives were drawn from a single clade, suggesting that susceptibility may cluster in patterns not captured directly by our markers.

Adult↗

PubMed2004

Under- and overreporting of energy is related to obesity, lifestyle factors and food group intakes in Jamaican adults.

OBJECTIVE: Research in industrialised countries has documented a high prevalence of underreported energy intakes associated with characteristics such as obesity. This paper examines the prevalence, patterns and impact of energy under- and overreporting on diet-obesity relationships in a middle-income developing country. DESIGN: A 70-item food-frequency questionnaire was used. Underreporters had reported energy intakes <1.35 x basal metabolic rate (BMR), overreporters >2.4 x BMR. Multinomial models were used to identify characteristics associated with implausible reporting. Intakes were compared across reporting groups to assess evidence of bias. Associations between diet and obesity were compared with and without adjustment for implausible reporting. SETTING: Spanish Town, neighbouring the capital city of Kingston, Jamaica. SUBJECTS: Eight hundred and ninety-one Jamaican adults, aged 25-75 years, were randomly recruited. RESULTS: More women than men (38.6% vs. 22.5%) underreported, but more men overreported energy (23.7% vs. 16.0%). Underreporting was positively associated with obesity, special diets, smoking and age; age was inversely associated with overreporting. Underreporters estimated lower energy from potentially socially undesirable food groups (e.g. snacks) and higher intakes of 'healthy' foods (e.g. fruit) than did plausible reporters. For some of these food groups, significant differences in intakes among normal-weight versus obese subjects observed among plausible reporters were absent when implausible reporters were included. In models of food group-obesity associations, adjusting for implausible energy yielded more credible results that more closely resembled findings in plausible reporters. CONCLUSIONS: Energy under- and overreporting are highly prevalent in Jamaica. Adjusting for implausible reporting may help to reduce bias in diet-health outcome associations.

Adult↗

PubMed2004

Historic and early life origins of hypertension in Africans.

Cardiovascular disease (CVD) causes 12.4 million deaths annually, most (9.6 million) occurring in developing countries. Hypertension, the most common CVD, arises within the context of obesity, but the underlying mechanisms remain obscure. Obesity and salt intake are two important risk factors for hypertension and are the focus of this paper. Traditional African populations show a low prevalence of hypertension, but hypertension is more common in migrant African populations in the West than in other ethnic groups. One explanation is genetic, but no causative gene has been confidently identified. Nongenetic susceptibilities such as fetal programming are an alternative explanation. Hypothetically, fetal programming induced by transient stimuli permanently alters fetal structure and function at the cellular, organ and whole-body levels. Birth weight is inversely related to blood pressure and hypertension risk, suggesting that susceptibility to hypertension risk factors such as obesity and salt sensitivity are themselves programmed. In support of this hypothesis, obesity (especially central obesity) is also inversely related to size at birth. Likewise, salt sensitivity might derive from undernutrition in utero, reducing the nephron number and resetting the pressure-natriuresis curve rightward. However, no robust human data or evidence of enhanced salt sensitivity among African-origin populations exist. In the United States, blacks have a greater prevalence of low birth weight than whites, suggesting that the higher prevalence of hypertension among blacks is related to fetal programming. Nevertheless, we need to be scrupulous in ascribing risk to the myriad other confounders of this relationship, including environmental and behavioral correlates of ethnicity, before concluding that excess risk of hypertension in Africans is programmed in utero.

Africa↗

PubMed2004

Supplementation with aromatic amino acids improves leucine kinetics but not aromatic amino acid kinetics in infants with infection, severe malnutrition, and edema.

We investigated whether supplementation with an aromatic amino acid (AAA) cocktail consisting of 0.5 mmol each of phenylalanine, tryptophan, and tyrosine compared with isonitrogenous amounts of alanine (Ala) would improve measures of protein kinetics in 14 (8 with AAA, 6 Ala) children with edematous malnutrition (aged 6-24 mo) during the infected acute malnourished state. Supplementation started immediately after the baseline experiment, 2 d postadmission and continued to the end of the acute phase of treatment. The second (postsupplementation) experiment was done approximately 12 d postadmission. We measured leucine kinetics, phenylalanine and tyrosine fluxes, using an i.g. 8-h prime continuous infusion of (2)H(3)-leucine, and an i.v. 6-h prime continuous infusion of (13)C-leucine, (2)H(2)-tyrosine, and (2)H(5)-phenylalanine in the fed state. Leucine flux tended to be faster (P = 0.06) in the AAA group compared with Ala group after supplementation (mean difference +/- SEM): 22.6 +/- 10.9 micromol/(kg . h). The rate of leucine appearance from protein breakdown [28.1 +/- 9.4 micromol/(kg . h)] and the nonoxidative disposal of leucine [i.e., leucine to protein synthesis; 35.4 +/- 12.9 micromol/(kg . h)] were faster (P < 0.02) in the AAA group than in the Ala group. There was no significant effect of supplementation on leucine splanchnic metabolism, phenylalanine, and tyrosine fluxes. These findings are consistent with the hypothesis that the blunting of the protein catabolic response to infection in children with edematous malnutrition syndrome is due to limited availability of aromatic amino acids.

Alanine↗

PubMed2003

Income, education, and blood pressure in adults in Jamaica, a middle-income developing country.

BACKGROUND: At present, little is known about how socioeconomic status (SES) is related to blood pressure (BP) and hypertension in developing countries. This cross-sectional study examined associations between SES and BP in 2082 adults from a peri-urban area of Jamaica, a middle-income developing country. METHODS: Hypertension (systolic BP >/=140 mmHg, diastolic BP >/=90 mmHg or current hypertensive medication use) was estimated based on self-reported medication use and the mean of the second and third of three manual BP measurements. Income and education were self-reported. Linear or logistic regressions were used to estimate multivariate associations between BP or hypertension and SES. RESULTS: Hypertension prevalence was 20% in men and 28% in women. In both men and women, the income distributions of BP and hypertension were non-linear, indicating elevated levels in low as well as in high-income groups. In contrast to the negative relationships typical for industrialized countries, multivariate-adjusted BP and hypertension were highest in the wealthiest women. In men with some high school education, income was positively associated with BP, while there were negative associations in men with lesser education. Unlike women, mean BP were highest in poor men with limited education. Low SES men were also least likely to receive diagnosis and treatment. CONCLUSIONS: Socioeconomic status is related to BP and hypertension in Jamaica, although relationships are non-linear. Behavioural and environmental factors that explain elevated BP among both low and high SES adults in developing countries must be identified to develop effective prevention strategies.

Adult↗

PubMed2002

Non-fatal violence-related injuries in Kingston, Jamaica: a preventable drain on resources.

Using data for a one-year period from the Kingston Public Hospital (KPH) in Jamaica, we describe patterns of non-fatal violence-related injuries, and carry out simulation analysis to estimate rates of hospital admission under various injury reduction scenarios, and the potential savings that can be realized by reducing violent crimes. In this period there were 6107 registered violence-related visits to the KPH representing 11.5% of all recorded visits. Of these 16.6% (1001) were admitted. The most common methods of inflicting injury was by stabbing (52.1%), blunt injuries (37.9%) and gunshot wounds (7.3%). Multivariate analyses indicated that gunshot injuries, stab injuries, being male between the ages of 15 and 44 years, receiving the injury in November or December, and being injured by a stranger or unknown assailant, were significant correlates of a higher probability of admission. Simulation analysis with various injury reduction scenarios indicated decreases in the probability of admission ranging from 12% to 44%, with estimated savings of up to 31% of the annual supplies budget of KPH.

Adolescent↗

PubMed2002

Response of splanchnic and whole-body leucine kinetics to treatment of children with edematous protein-energy malnutrition accompanied by infection.

BACKGROUND: Although the reduction in whole-body protein turnover and net protein loss induced by protein-energy malnutrition (PEM) has been well documented, it is unclear whether the protein-sparing mechanisms elicited by chronically inadequate intakes of dietary protein and energy are affected by the protein catabolic response to infection. OBJECTIVE: The objective of this study was to determine whether the presence of infection alters the PEM-induced reduction in whole-body protein metabolism. DESIGN: We determined whole-body leucine kinetics in 4 boys and 3 girls aged 6-15 mo with edematous PEM and infection approximately 3 d after admission (study 1), when they were both infected and malnourished; approximately 11 d after admission (study 2), when infection had resolved but they were still anthropometrically malnourished; and at recovery (study 3), when weight-for-length was at least 90% of that expected. RESULTS: The children had significantly less leucine flux in both study 1 and study 2 than they had in study 3. There were no significant differences in the amount of leucine released from protein breakdown or used for protein synthesis between study 1 and study 2. There were no significant differences in leucine balance or in either the amount or percentage of enteral leucine extracted by the splanchnic tissues among the 3 studies. CONCLUSIONS: When subjects are in the fed state, severe PEM induces a marked reduction in whole-body protein synthesis and breakdown rates, and the presence of infection does not alter this adaptation and hence the overall protein balance. A corollary is that children with severe PEM do not mount a protein catabolic response to infection.

Deuterium↗

PubMed2002

Cysteine supplementation improves the erythrocyte glutathione synthesis rate in children with severe edematous malnutrition.

BACKGROUND: Children with severe edematous malnutrition have higher than normal oxidant damage and lower concentrations of the antioxidant reduced glutathione (GSH), which are associated with slower synthesis of GSH and with low extra- and intracellular concentrations of the precursor amino acid cysteine. OBJECTIVE: We tested whether early dietary supplementation with cysteine could restore a normal GSH concentration and synthesis rate in these children. DESIGN: Erythrocyte cysteine and GSH concentrations and the fractional and absolute synthesis rates of GSH were measured in 2 groups of 16 edematous malnourished children, 10 boys and 6 girls aged 6-18 mo, at 3 times after hospital admission: at approximately 2 d (period 1), when they were malnourished and infected; at approximately 11 d (period 2), when they were malnourished but cleared of infection; and at approximately 50 d (period 3), when they had recovered. Supplementation with either 0.5 mmol. kg(-1). d(-1) N-acetylcysteine (NAC group) or alanine (control group) started immediately after period 1 and continued until recovery. RESULTS: From period 1 to period 2 the concentration and the absolute synthesis rate of GSH increased significantly (P < 0.05) in the NAC group but not in the control group. The increases in the GSH concentration and synthesis rate were approximately 150% and 510% greater, respectively, in the NAC group than in the control group. The increases in the NAC group were associated with a significant effect of supplement (P < 0.03) on erythrocyte cysteine concentration. CONCLUSION: These results suggest that the GSH synthesis rate and concentration can be restored during the early phase of treatment if patients are supplemented with cysteine.

Acetylcysteine↗

PubMed2002

The acute-phase protein response to infection in edematous and nonedematous protein-energy malnutrition.

BACKGROUND: Immune structure and function are more compromised in edematous protein-energy malnutrition (PEM) than in nonedematous PEM. Whether the positive acute-phase protein (APP) response to infection is affected remains unknown. OBJECTIVE: We assessed whether children with edematous PEM can mount a general APP response and compared the kinetic mechanisms of the response in children with edematous PEM with those in children with nonedematous PEM. DESIGN: Plasma C-reactive protein, alpha(1)-acid glycoprotein, alpha(1)-antitrypsin, haptoglobin, and fibrinogen concentrations and the fractional and absolute synthesis rates of alpha(1)-antitrypsin, haptoglobin, and fibrinogen were measured in 14 children with edematous PEM, aged 11.4 +/- 2 mo, and 9 children with nonedematous PEM, aged 10.1 +/- 1.4 mo, at 3 times: approximately 2 d after hospital admission (period 1), when they were malnourished and infected; approximately 8 d after admission (period 2), when they were malnourished but free of infection; and approximately 54 d after admission (period 3), when they had recovered. RESULTS: Children with edematous and nonedematous PEM had higher plasma concentrations of 4 of 5 APPs in period 1 than in period 3. The magnitude of the difference in concentration and in the rate of synthesis of the individual APPs was less in the children with edematous PEM than in those with nonedematous PEM. The kinetic data show that the characteristics of the APP response were different in the 2 groups. CONCLUSIONS: These results suggest that severely malnourished children can mount only a partial APP response to the stress of infection and that the magnitude of this response is less in those with edema.

Acute-Phase Proteins↗

PubMed2002

Application of stable isotopic techniques in the prevention of degenerative diseases like obesity and NIDDM in developing societies.

Economic development in developing societies characterized by industrialization, urbanization, and globalization has seen the emergence of an epidemic of diet- and life-style-related chronic degenerative diseases. A research project was initiated under the aegis of the International Atomic Energy Agency (IAEA), Vienna, Austria under its Coordinated Research Programme (CRP) to promote the use of stable isotopic techniques to document the extent of the problem and to understand the determinants of this epidemic. The principal objectives of this CRP involving countries both in the North and the South are to define the magnitude of the problem of obesity and non-insulin dependent diabetes mellitus (NIDDM) in developing countries, to identify the vulnerable groups at increased risk, and to attempt to describe the metabolic and physiological mechanisms underlying this phenomenon. These comparative international studies of obesity and NIDDM are looking at the effects of childhood malnutrition (Brazil) and socioeconomic differentials (Mexico) on adult risk factors; the composition of the daily diet on obesity (Chile); levels of patterns of physical activity of older adults (China) as well as their influence on weight gain and obesity (Cuba, Nigeria); the impact of body composition and energy expenditure on the evolution frank diabetes from impaired glucose tolerance (Jamaica), and of body compositional changes and the role of inflammatory cytokines on impaired glucose tolerance (India). The last study conducted in New Zealand was aimed at comparing the energy expenditures of Maori (Pacific Island) with New Zealanders of European descent.

Africa↗