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R S Cooper

Publications and source records attributed to R S Cooper.

At least 55 records · Page 3Linked to original sources
PubMed2000

Heritability of angiotensin-converting enzyme and angiotensinogen: A comparison of US blacks and Nigerians.

Angiotensinogen (AGT) and angiotensin I-converting enzyme (ACE) are heritable traits, but whether the environmental context influences heritability has not been examined. Known genetic factors explain only a portion of variation in AGT and ACE, and levels of both proteins are influenced by the environment. The African diaspora provides an opportunity to compare these traits in genetically related populations in contrasting environments. As part of a study of the genetics of hypertension, we examined families that included 1449 Nigerians and 1147 African Americans. Body mass index (weight [kg]/height [m](2)) was 21 kg/m(2) in Nigeria and 29 kg/m(2) in the United States, which is consistent with a large environmental contrast. AGT was considerably higher among African Americans (1919 versus 1396, P<0.01), whereas ACE was higher in Nigerians (630 versus 517, P<0.01). A household effect was observed among the Nigerian families (spouse correlations 0.30 for AGT, 0.18 for ACE), and correlations among first-degree relatives were large (0.42 to 0. 51 and 0.36 to 0.38 for AGT and ACE, respectively). Among African Americans, the familial aggregations of AGT and ACE were very limited, and the familial correlation for AGT was not different from zero. Heritability was 77% for AGT and 67% for ACE in Nigeria and 18% for AGT and ACE in the United States. The familial patterns of body mass index and blood pressure were similar among both family sets. In conclusion, less familial aggregation was observed for AGT and ACE in the United States than in Nigeria, most likely reflecting a greater random individual environmental effect on these traits. Variation in heritability of traits could influence the power of epidemiological studies to identify genetic effects.

Adult↗
PubMed2000

The Idikan adult mortality study.

The Idikan adult mortality study is designed to explore the usefulness of the verbal autopsy methodology in the determination of cause-specific adult mortality. Such data have been largely unavailable in developing countries. Members of a stable urban community (4333 adults) were registered in their family units and followed up every 3 months to ascertain deaths, exits and new entries to the study population. Deaths were investigated by means of a verbal autopsy, which was administered by a trained interviewer to the relative closest to the decedent. Two physicians independently studied the results and assigned a cause of death, and these were then confirmed or resolved by a senior physician colleague. Hospitals where deaths occurred were visited and assignable cause of death was obtained where available and compared with the cause assigned by verbal autopsy. Only 8 of the 60 investigated deaths were confirmed to have occurred in a hospital in the first 2 years of the study. The cause of death assigned by verbal autopsy agreed moderately both between the independent coders as well as with the hospital assigned cause of death using the Kappa statistics for agreement beyond chance. We therefore concluded that verbal autopsies appear moderately useful for adult death statistics (Kappa = 0.23 to 0.1). Accumulation of more hospital deaths is needed, however, to make more definite conclusions about the validity of the technique.

Adolescent↗
PubMed1999

Evidence for the involvement of JAK/STAT pathway in the signaling mechanism of interleukin-17.

Interleukin-17 is a T-cell-derived pro-inflammatory cytokine, exhibiting multiple biological activities in a variety of cells and believed to fine tune all general phases of hematopoietic response. However, the signaling mechanism of this novel cytokine remains unknown. Here, we report for the first time that the early signaling events triggered by interleukin-17 involve tyrosine phosphorylation of several members of the JAK and STAT proteins in human U937 monocytic leukemia cells. Immunoprecipitation with specific antibodies followed by Western blot analysis with antiphosphotyrosine antibody has shown that in U937 cells, interleukin-17 induces time-dependent stimulation of tyrosine phosphorylation of JAK 1, 2 and 3, Tyk 2 and STAT 1, 2, 3 and 4 within 0.5 to 30 min. Interleukin-17-mediated tyrosine phosphorylation of these proteins strongly suggests that the JAK/STAT signaling pathway may play a major role in transducing signals from interleukin-17 receptors to the nucleus.

Blotting, Western↗
PubMed1999

Seeking causal explanations in social epidemiology.

Social factors are associated with a wide variety of health outcomes. Social epidemiology has successfully used the traditional methods of surveillance and description to establish consistent relations between social factors and health status. Epidemiology as an etiologic science, however, has been largely ineffective in moving toward causal explanations for these observed patterns. Using the counterfactual approach to causal inference, the authors describe several fundamental problems that often arise when researchers seek to infer explanatory mechanisms from data on social factors. Contrasts that form standard causal effect estimates require implicit unobserved (counterfactual) quantities, because observational data provide only one exposure state for each individual. Although application of counterfactual arguments has successfully advanced etiologic understanding in other observational settings, the particular nature of social factors often leads to logical contradictions or misleading inferences when investigators fail to clearly articulate the counterfactual contrasts that are implied. For example, because social factors are often attributes of individuals and are components of structured social relations, random assignment is not plausible even as a hypothetical experiment, making typical epidemiologic contrasts inappropriate and the inference equivocal at best. Accordingly, more deliberate and creative approaches to causal inference in social epidemiology are required. Infectious disease epidemiology and systems analysis provide examples of approaches to causal inference that can be used when statistical mimicry of simple experimental designs is not tenable. In an era of increasing social inequality, valid approaches for the study of social factors and health are needed more urgently than ever.

Black or African American↗
PubMed1999

Prediction of coronary heart disease mortality in blacks and whites: pooled data from two national cohorts.

Statistical models used to predict personal risk of death from coronary heart disease (CHD) have been based on studies among white populations. We compared the predictive functions derived from black and white men and women, using the pooled data of 2 national cohorts: the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study and the Second National Health and Nutrition Examination Survey (NHANES II) Mortality Study. The participants included 6,937 white men, 940 black men, 9,202 white women, and 1,463 black women aged 30 to 74 years who were free of CHD at baseline. The 2 cohorts were followed for 20 and 15 years, respectively. There were no significant differences between blacks and whites in the magnitude of the Cox coefficients for most of the personal risk factors (i.e., age, systolic blood pressure, serum total cholesterol, smoking, and diabetes mellitus status) for men and women. The receiver operating characteristic (ROC) analyses, with all risk factors considered collectively, suggest that the models have similar ability to rank personal relative risk among blacks and whites. The areas under the ROC curve were 0.77 and 0.76 for white and black men, respectively, and 0.84 and 0.82 for white and black women, respectively. However, the equation derived from white men overestimated the 15-year cumulative CHD mortality in black men by about 60%. Thus, predictive functions derived from 1 demographic group (e.g., whites) can be applied to another subgroup (e.g., blacks) to rank personal risk. However, prediction of absolute risk is less accurate.

Black or African American↗
PubMed1999

Black-white differences in disability and morbidity in the last years of life.

To assess black-white differences in disability and morbidity in the last years of life, the authors analyzed data from the National Health Interview Survey from 1986 to 1994, with mortality follow-up through December 1995. A baseline household interview was conducted for 10,187 decedents aged 50 years and over within 2 years before death. Data collected included long-term limitation of activity, number of chronic conditions, number of bed days, doctor visits, and days of short hospital stay during the year preceding the interview. For both blacks and whites, educational attainment was inversely associated with disability/morbidity indices. Black decedents had greater morbidity compared with whites, and this difference was consistent across educational levels. Adjustment for education reduced the black-white difference in limitation of activity score by 32%, bed days by 59%, and hospital stay days by 40%. This study from a national representative US sample indicates that black decedents experienced greater disability/morbidity and worse quality of life through their last few months or years of life. Educational attainment was associated with morbidity before death and accounted for much of the black-white difference.

Activities of Daily Living↗
PubMed1999

Self-reported health status and mortality in a multiethnic US cohort.

The authors examined the relation between self-reported health status and mortality among the following racial/ethnic groups: Native Americans, Asian/Pacific Islanders, blacks, whites, and Hispanics. They pooled 1986-1994 data from the National Health Interview Survey to obtain information on more than 700,000 cohort participants. Although fewer than 5,000 Native Americans are included in this cohort, the data provide information previously unavailable for this group. Also included are almost 17,000 Asian/Pacific Islanders, over 90,000 blacks, and over 50,000 Hispanics. The authors found strong associations between self-reported health status and both socioeconomic status and subsequent mortality. A self-report of fair or poor health was associated with at least a twofold increased risk of mortality for all racial/ethnic groups. Even after adjustment for socioeconomic status and measures of comorbidity, a significant relation was found between self-reported health status and subsequent mortality. The authors found that self-reported health status is a strong prognostic indicator for subsequent mortality for both genders and all racial/ethnic groups examined. These results emphasize the utility of using simple filter questions in population research.

Adult↗
PubMed1999

Abdominal adiposity in six populations of West African descent: prevalence and population attributable fraction of hypertension.

OBJECTIVES: The objective of this investigation was to examine the prevalence of abdominal adiposity and its association with the prevalence of hypertension among African descent populations in Nigeria, Cameroon, Jamaica, St. Lucia, Barbados, and the United States (US). RESEARCH METHOD: The data for this investigation were obtained from the International Collaborative Study on Hypertension in Blacks. Hypertension was defined as mean diastolic blood pressure > or =90 mmHg, systolic blood pressure > or = 140 mmHg or current treatment with prescribed anti-hypertension medication. Abdominal overweight was defined as waist circumference (WC) > or =94 and > or =80 cm for men and women, respectively. Abdominal obesity was defined as WC > or =102 and > or =88 cm for men and women, respectively. We estimated the site-specific prevalence of abdominal overweight and obesity across age and body mass index cut-points. We also calculated the population attributable fraction (AF) of hypertension due to abdominal adiposity. RESULTS: The prevalence of hypertension in these populations was tightly linked to abdominal adiposity. Increases in abdominal overweight accompanied an increasing degree of Westernization, rising from 6.4% and 26.3% in Nigeria, 16.5% and 62.8% in Cameroon, 15.8% and 58.6% in Jamaica, 14.3% and 62.1% in St. Lucia, 21.4% and 70.3% in Barbados to 38.9%, and 76.4% in the US for men and women, respectively. The corresponding values for abdominal obesity were 1.6% and 12.3% in Nigeria, 5.1% and 38.9% in Cameroon, 5.5% and 34.0% in Jamaica, 2.7% and 40.7% in St. Lucia, 7.8% and 44.7% in Barbados to 21.7% and 54.1% in the US for men and women, respectively. Body mass index-adjusted estimates of AF suggest that in most of these populations, especially in females, avoidance of abdominal overweight or obesity would help to curb the development of hypertension. DISCUSSION: An important public health challenge is to clarify how lifestyle factors influence risks of abdominal adiposity and ultimately the increased risk of cardiovascular diseases.

Abdomen↗
PubMed1999

How generalizable are coronary risk prediction models? Comparison of Framingham and two national cohorts.

BACKGROUND: Previous models used to predict individual risk of death from coronary heart disease (CHD) were developed from data of 3 decades ago from the Framingham Heart Study. CHD mortality rates have declined markedly since that period as a result of improvement in both risk factor status and medical interventions. Generalization of the results from this one study to the population at large remains a matter of concern. We compared predictive functions derived from the major risk factors for CHD from Framingham and 2 more recent national cohorts, the First and Second National Health and Nutrition Examination Survey (NHANES I and NHANES II). METHODS AND RESULTS: The participants included 1846 men and 2323 women 35 to 69 years of age and free of CHD at the fourth examination (1954 to 1958) from the Framingham Study; 2753 men and 3858 women from the NHANES I (1971 to 1975); and 2655 men and 3050 women from NHANES II (1976 to 1980). The 3 cohorts were monitored for 24, 20, and 15 years, respectively. Significant heterogeneity existed among studies in the magnitude of the Cox coefficients for the individual factors (ie, age, systolic blood pressure, serum total cholesterol, and smoking status), especially among men. When risk factors were considered collectively, however, functions derived from and applied to different cohorts had a similar ability to rank individual risk. The areas under the receiver operating characteristic curves were 0. 71 to 0.76 in men and 0.76 to 0.81 in women when different risk functions were applied to their own population or to a second population. The cumulative CHD survival observed in women in the 2 national cohorts was close to what was predicted from the Framingham equation. However, Framingham overestimated the cumulative CHD mortality rates in men in NHANES I and NHANES II. CONCLUSIONS: The Framingham risk model for the prediction of CHD mortality rates provides a reasonable rank ordering of risk for individuals in the US white population for the period 1975 to 1990. However, prediction of absolute risk is less accurate.

Adolescent↗
PubMed1999

Association of waist circumference with ApoB to ApoAI ratio in black and white Americans.

BACKGROUND: Although numerous studies have demonstrated obesity as an aspect of the insulin resistance syndrome in cardiovascular disease (CVD), the mechanism is not clear. Central adiposity, acting through many CVD risk factors, including, plasma glucose, insulin, total cholesterol, low density lipoprotein-cholesterol (LDL-C) and lipoprotein moities-apolipoprotein B (ApoB), apolipoprotein A-I (ApoAI), by atherogenic and thrombotic mechanisms has been proposed as a possible mechanism. In this study, we examined the relationship between central fat distribution (defined by waist circumference) and the ratio of these lipoproteins (ApoB/ApoAI). SUBJECTS AND METHODS: Association between ApoB/ApoAI ratio and waist circumference was compared in Blacks (n = 854) and Whites (n = 2552) using the NHANES III population-based samples. Correlation analyses and multiple regression analyses were used to determine the association between ApoB/ApoAI and waist circumference, controlling for age, body mass index (BMI), race, gender, plasma glucose, insulin, serum triglyceride and total cholesterol. RESULTS: Adjusting for age, ApoB/ApoAI was significantly correlated with waist circumference (Black men: r = 0.38, White men: r = 0.26, Black women: r = 0.20, White women: r = 0.36) (all P < 0.01). Adjusting for age and triglyceride or insulin, waist circumference was also positively correlated with CVD risk factors including, ApoB, LDL-C, plasma glucose and fasting insulin, and inversely correlated with ApoAI and HDL-C in Blacks and Whites (P < 0.05). Overall, triglyceride and total cholesterol were the strongest predictors of ApoB/ApoAI in Blacks and Whites adjusting for age, BMI and insulin, than waist girth (P < 0.01). CONCLUSIONS: The result of this study suggests the need to investigate ApoB/ApoAI as another possible facet in the insulin resistant syndrome.

Adolescent↗
PubMed1999

The long isoform uncoupling protein-3 (UCP3L) in human energy homeostasis.

The biological role(s) proposed for UCP3 in energy homeostasis have been based primarily upon amino acid sequence homology to UCP1. Spontaneous mutations of UCP3> have been described in humans, but not in rodents. The functional consequences-or lack thereof-of these mutations in humans will be of great importance in elucidating the biology of this protein. The results of two such studies are summarized here.

Animals↗
PubMed1999

Abdominal obesity in the United States: prevalence and attributable risk of hypertension.

OBJECTIVE: The aim of this study was to determine the prevalence of abdominal obesity and its impact on the risks of hypertension in the US adult population. DESIGN AND METHODS: Data from the third US National Health and Nutrition Examination Surveys, 1988-1994, were utilised. Abdominal obesity was defined as waist circumference > or =102 cm in men and > or =88 cm in women. Hypertension was defined as mean diastolic blood pressure > or =90 mm Hg, systolic blood pressure > or =140 mm Hg or current treatment with prescribed hypertension medication. Prevalences of abdominal obesity were estimated in non-Hispanic White, non-Hispanic Black and Hispanic Americans. Gender-specific logistic regression analysis using empirical waist cut-off points was used to determine the risks of hypertension. The impact of abdominal adiposity on risk of hypertension was estimated from population-attributable risk adjusting for age, current smoking and alcohol intake. RESULTS: The prevalences of abdominal obesity were 27.1%, 20.2% and 21.4% in White, Black and Hispanic men, respectively. The corresponding values in women were 43.2%, 56.0% and 55.4%. Abdominal obesity was found to be associated with a two to three-fold increased risk of hypertension in this population. In men, the attributable risk percent ranged from 20.9% in Hispanics to 27.3% in Whites and in women ranged from 36.5% in Whites to 56.5% in Hispanics. We estimated that 24 million adult men and 40 million adult women of Hispanic and non-Hispanic Black and White ethnicity were suffering from abdominal obesity. CONCLUSIONS: In this population, hypertension appears to be associated with abdominal obesity. The estimates of population attributable risks suggest that the risk of hypertension could be potentially reduced if waist size were reduced to <102 cm in men and <88 cm in women.

Abdomen↗
PubMed1999

Diabetes in the Caribbean: results of a population survey from Spanish Town, Jamaica.

AIMS: To characterize the prevalence of diabetes and associated risk attributes in the Jamaican population. METHODS: A random population sample was recruited by door-to-door canvassing (n = 1303). A final participation of 60% was achieved. Oral glucose tolerance testing was conducted after an overnight fast and standard anthropometric and demographic data were collected. RESULTS: The prevalence of Type 2 diabetes mellitus was 9.8% (95% confidence interval (CI) 7.2-12.4) among men and 15.7% (95% CI 13.1-18.3) among women with an overall prevalence of 13.4% (95% CI 11.5-15.2). Impaired glucose tolerance was found among 12.3% of men and 14.7% of women. The sex patterns were consistent with a fourfold excess of obesity in women compared to men. The odds ratios for diabetes, fourth vs. first quartiles were 5.42 (95% CI 2.02-16.88) in men and 3.32 (95% CI 1.73-6.63) in women for body mass index (BMI) and 17.39 (95% CI 3.86-78.27) in men and 5.48 (95% CI 2.84-11.00) in women for WHR in a logistic model controlling for age. The population attributes risk percentage, for diabetes, of being overweight and having waist-to-hip ratio (WHR) greater than the median (0.80) were 66% and 80%, respectively. The contribution of central obesity, as characterized by WHR, was also significant in sex-specific multivariate models that included age and BMI. Prevalent hypertension and family history of diabetes were likewise associated with increased odds of having the disease. CONCLUSIONS: The prevalence of diabetes in Jamaica now exceeds that observed among European-origin populations and reflects the emerging epidemic of obesity. The excess risk for this population could not be attributed entirely to relative weight. The pronounced sexual dimorphism in diabetes prevalence most likely reflects the substantial excess of obesity among women compared to men. Like many other island nations, Caribbean societies now appear to be at substantial risk of diabetes.

Aged↗
PubMed1999

Maximum-likelihood generalized heritability estimate for blood pressure in Nigerian families.

Elevated blood pressure (BP) is more common in relatives of hypertensives than in relatives of normotensives, indicating familial resemblance of the BP phenotypes. Most published studies have been conducted in westernized societies. To assess the ability to generalize these estimates, we examined familial patterns of BP in a population-based sample of 510 nuclear families, including 1552 individuals (320 fathers, 370 mothers, 475 sons, and 387 daughters) from Ibadan, Nigeria. The prevalence of obesity in this community is low (body mass index: fathers, 21.6; mothers, 23.6; sons, 19.2; and daughters=21.0 kg/m2). The BP phenotype used in all analyses was created from the best regression model by standardizing the age-adjusted systolic blood pressure (SBP) and diastolic blood pressure (DBP) to 0 mean and unit variance. Heritability was estimated by use of the computer program SEGPATH from the most parsimonious model of "no spouse and neither gender nor generation difference" as 45% for SBP and 43% for DBP. The lack of a significant spouse correlation is consistent with little or no influence of the common familial environment. However, the heritability estimate of <50% for both SBP and DBPs reinforces the importance of the nonshared environmental effect.

Adult↗
PubMed1999

Socioeconomic status and morbidity in the last years of life.

OBJECTIVES: This study evaluated the effect of socioeconomic status, as characterized by level of education, on morbidity and disability in the last years of life. METHODS: The analysis used data from the National Health Interview Survey (1986-1990), with mortality follow-up through December 1991. RESULTS: Among 10,932 decedents 50 years or older at baseline interview, educational attainment was inversely associated with long-term limitation of activity, number of chronic conditions, number of bed days, and days of short hospital stay during the year preceding the interview. CONCLUSIONS: Decedents with higher socioeconomic status experienced lower morbidity and disability and better quality of life even in their last years of life.

Absenteeism↗
PubMed1999

Genetic and physiologic analysis of the role of uncoupling protein 3 in human energy homeostasis.

By virtue of its potential effects on rates of energy expenditure, uncoupling protein 3 (UCP3) is an obesity candidate gene. We identified nine sequence variants in UCP3, including Val9Met, Val102Ile, Arg282Cys, and a splice site mutation in the intron between exons 6 and 7. The splice mutation results in an inability to synthesize mRNA for the long isoform (UCP3L) of UCP3. Linkage (sib pair), association, and transmission disequilibrium testing studies on 942 African-Americans did not suggest a significant effect of UCP3 on body composition in this group. In vastus lateralis skeletal muscle of individuals homozygous for the splice mutation, no UCP3L mRNA was detectable; the short isoform (UCP3S) was present in an increased amount. In this muscle, we detected no alterations of in vitro mitochondrial coupling activity, mitochondrial respiratory enzyme activity, or systemic oxygen consumption or respiratory quotient at rest or during exercise. These genetic and physiologic data suggest the following possibilities: UCP3S has uncoupling capabilities equivalent to UCP3L; other UCPs may compensate for a deficiency of bioactive UCP3L; UCP3L does not function primarily as a mitochondrial uncoupling protein.

Alternative Splicing↗