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Biomedical subjects

R S Cooper

Publications and source records attributed to R S Cooper.

At least 91 records · Page 5Linked to original sources
PubMed1997

Mortality from coronary heart disease and cardiovascular disease among adult U.S. Hispanics: findings from the National Health Interview Survey (1986 to 1994).

OBJECTIVES: We sought to estimate the coronary heart disease (CHD) and cardiovascular disease (CVD) mortality experience of U.S. Hispanics. BACKGROUND: Limited information is available concerning the mortality from CHD among U.S. Hispanics, the nation's second largest minority group. METHODS: The study used data from the National Health Interview Survey (1986 to 1994), including representative national samples of 246,239 non-Hispanic whites, 38,042 blacks and 14,965 Hispanics who were > or = 45 years old at baseline. Mean follow-up of mortality was 5 years (range 1 to 10). RESULTS: During the follow-up period, 27,702 whites (11%), 4,976 blacks (13%) and 1,061 Hispanics (7%) died. Among men, the age-adjusted total mortality per 100,000 person-years was 3,089 in whites and 2,466 in Hispanics, and among women, it was 1,897 and 1,581 in whites and Hispanics, respectively. The Hispanic/white mortality rate ratio for CHD was 0.77 (95% confidence interval [CI] 0.64 to 0.93) and 0.82 (95% CI 0.66 to 1.01) for men and women, respectively. The rate ratio was 0.79 (95% CI 0.68 to 0.91) and 0.80 (95% CI 0.69 to 0.94), respectively, for mortality from cardiovascular diseases. Given the lower all-cause mortality in Hispanics, the proportion of total deaths due to CHD and CVD was similar between the two populations for the same gender and were, respectively, 29.7% and 44.7% in white men, 28.1% and 44.3% in Hispanic men, 24.9% and 43.2% in white women and 24.1% and 41% in Hispanic women. CONCLUSIONS: These data from a cohort of a large national sample are consistent with vital statistics that show that all-cause, CHD and CVD mortality is approximately 20% lower among adult Hispanics than among whites in the United States.

Aged↗
PubMed1997

Relation between body mass index and body fat in black population samples from Nigeria, Jamaica, and the United States.

Body mass index (BMI) is the most commonly used measure of obesity. Recently, some investigators have advocated direct measurement of adiposity rather than use of the BMI. This study was undertaken to determine the ability of BMI to predict body fat levels in three populations of West African heritage living in different environments. A total of 1,054 black men and women were examined in Nigeria, Jamaica, and the United States during 1994 and 1995. A standardized protocol was used to measure height, weight, waist and hip circumferences, and blood pressure at all sites; percentage of body fat was estimated using bioelectrical impedance analysis. Percentage of body fat and BMI were highly correlated within site- and sex-specific groups, and the resulting r2 ranged from 0.61 to 0.85. The relation was quadratic in all groups except Nigerian men, in whom it was linear. The regression coefficients were similar across sites, yet the mean body fat levels differed significantly (p < 0.001) as estimated by the intercept, making intersite comparison difficult. Compared with BMI, percentage of body fat was not a better predictor of blood pressure or waist or hip circumference.

Adult↗
PubMed1997

Evidence for the involvement of LCK and MAP kinase (ERK-1) in the signal transduction mechanism of interleukin-15.

Human IL-15 is a cytokine expressed by a variety of tissues and cells including myeloid progenitor cells and monocytes. It shares biologic properties of IL-2 and utilizes the beta subunit of the IL-2R. IL-15 regulates proliferation of activated B and NK cells and stimulates chemoattraction in blood T-lymphocytes, effects which are inhibited by an anti-IL-2R beta antibody. Because little is known about the mechanism(s) by which IL-15 signal is transduced, this study was conducted to identify some of the key molecules involved in IL-15-induced signaling cascade(s). We report that IL-15 induces tyr phosphorylation of the p75IL-2R beta and p64IL-2R gamma subunits and Shc. Also, it activates both p56lck and MAPK (ERK-1). These results strongly suggest that LCK and MAPK may play vital roles in mediation of cellular activation by IL-15.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1997

Prediction of mortality risk by different methods of indexation for left ventricular mass.

OBJECTIVES: We sought to compare the predictive value of echocardiographically determined left ventricular hypertrophy on death from all causes and cardiac mortality using various methods of indexation for left ventricular mass. BACKGROUND: Considerable controversy exists regarding the optimal method for indexing left ventricular mass to body size in the clinical setting. METHODS: The study included 988 consecutive patients who had both coronary angiograms and echocardiographic examinations in an inner-city public hospital in Chicago, Illinois. Patients were followed up for a mean of 7 years (range 2 to 11). RESULTS: Various left ventricular mass indexes (e.g., mass indexed for height, height2, height2.13, height2.7, body surface area and body surface area1.5 were highly correlated (r = 0.90 to 0.99). Used as a continuous measure, an increase in any left ventricular mass index was associated with similar risk of death from all causes and cardiac diseases. Although left ventricular hypertrophy assessed by mass indexed for body surface area using the published conventional partition values provided somewhat better prediction, the adjusted relative risk was in general not significantly different from hypertrophy based on other indexes. Patients with left ventricular hypertrophy defined concordantly by indexes based on both body surface area and height (or height2.7) had, by definition, the highest average mass indexes among all groups and experienced as much as a threefold greater risk of death than those without hypertrophy. A small proportion of patients (12%) who were classified into the hypertrophy group by height-based indexes alone, but not by body surface area, had a moderate increase in mass and showed no increase in risk, even though being overweight was extremely prevalent in this group. CONCLUSIONS: Because of the high correlation among various body size indexes, left ventricular hypertrophy, defined by different indexes for left ventricular mass, similarly confers increased risk of mortality in patients with or without coronary artery disease.

Body Constitution↗
PubMed1997

Race and the histologic grade of prostate cancer.

We collected data on the histologic grade, stage, and age at diagnosis of 4,114 cases of prostate cancer (1,380 blacks, and 2,734 whites) in the Chicago area. The relationship between histologic grade (high = poorly or undifferentiated vs. low = well or moderately differentiated) and race (black vs. white) was examined using logistic regression. After adjusting for stage (localized, regional, and distant), the odds of high histologic grade prostate cancer in blacks compared to whites equaled 1.7 (95% CI [1.4, 2.0], P < 0.0001). These data suggest that blacks have a significantly higher burden of high histologic grade prostate cancer than whites, even after adjustment for stage at presentation. This higher burden may explain, in part, their higher mortality rate from prostate cancer given the U.S. black vs. white difference in prostate cancer mortality of a similar magnitude.

Aged↗
PubMed1997

Serum distribution of lipoprotein(a) in African Americans and Nigerians: potential evidence for a genotype-environmental effect.

Differences in lipoprotein(a) [Lp(a)] levels across populations have been described and blacks are known to have higher Lp(a) values compared to whites. However, environmental factors which influence Lp(a) levels have been difficult to identify. We took advantage of the large environmental contrast which exists against a common genetic background between U.S. and Nigerian blacks to examine the relationship between Lp(a) and apolipoprotein(a) magnitude of apo(a) isoforms. Although the distribution of Lp(a) and apo(a) isoforms was nearly Gaussian in both populations, mean serum Lp(a) values were significantly higher in the United States than in Nigeria (20.5 vs. 12.7 mg/dl; P = 0.0001) and U.S. blacks had a higher frequency of the large molecular weight isoforms compared to Nigerians. Similar trends in the relationship between apo(a) isoform and Lp(a) concentration were seen in both populations; however, the magnitude of the effect was different. Compared to the Nigerians, U.S. blacks had significantly higher mean Lp(a) values for the same apo(a) isoform. The association of Lp(a) with low density lipoprotein-cholesterol (LDL-C) level was not significant after correcting for the contribution of Lp(a) cholesterol to LDL-C in both populations. Surprisingly, the association between Lp(a) and total-C remained significant (r = 0.20, P = 0.04) after similar correction for the contribution of Lp(a) cholesterol in the U.S. sample. Understanding the relationship between other factors including lifestyle characteristics capable of influencing total-C may help explain the unusually high Lp(a) level observed in this U.S. population.

Adult↗
PubMed1997

One size fits all: implications for assessing dietary behavior.

Accurate assessment of dietary behavior is central to the design, implementation, and evaluation of intervention programs aimed at behavior change, and use of an Eating Behaviors Questionnaire (EBQ) has been suggested for measuring dimensions of dietary fat behavior. The EBQ has proven useful in characterizing fat-related dietary patterns among middle-class, highly educated, highly motivated white women. To investigate the generalizability of the instrument, we provide findings from a community-based sample of 235 African-Americans in Maywood, Illinois, a middle-class working community outside Chicago. The sample consisted of 159 women and 76 men with an average age of 47.4 +/- 13.8 years for women and 48.1 +/- 12.1 years for men (mean +/- standard deviation; range, 18 to 87 years). The EBQ is based on four broad behavioral domains (ie, avoidance, modification, substitution, and replacement) associated with fat-related eating patterns. These behavioral domains are composed of specific dietary behaviors (factors). Using a scoring system that allowed all participants to be included in all analyses, we identified a set of factors characterizing eating patterns in our sample that differed from those reported previously. When the factors were converted to scales using unit scoring, the average value suggested a tendency toward a higher fat eating pattern. Results indicate that although behavioral domains appear to be constant across populations, fat-related eating patterns are not. These observations have implications for understanding the diversity of fat-related dietary patterns across groups and for planning appropriate behavior change strategies.

Adult↗
PubMed1997

Relative weight and mortality in U.S. blacks and whites: findings from representative national population samples.

PURPOSE: To examine the impact of relative weight on mortality in black and white men and women. METHODS: Two representative national populations samples were used: the NHANES-I Epidemiologic Follow-up Study (NHEFS), and the National Health Interview Survey (NHIS). The principal analysis focused on 13,242 participants in the NHEFS and 114,954 in the NHIS. Minimum mortality was estimated from both categorical analysis and a logistic model. RESULTS: Minimum mortality ranged from a body mass index (BMI) of 25 to 32 kg/m2. The model-estimated BMI of minimum mortality for NHEFS was 27.1 (24.8-29.4, 95% CI), 26.8 (24.7-28.9, 95% CI), 24.8 (23.8-25.9, 95% CI) and 24.3 (23.2-25.4, 95% CI); for black men, black women, white men and white women, respectively, whereas for NHIS the corresponding values were 30.2 (24.8-35.6, 95% CI) 26.4 (24.2-28.7, 95% CI), 27.1 (25.5-28.7, 95% CI), and 25.6 (24.2-27.0, 95% CI). In all groups the shape of the relative risk curve was virtually identical and a broad range of BMI values in the middle of the distribution was associated with low relative mortality risk. Averaging the results from both surveys, the observed BMI of minimum risk was 3.1 kg/m2 higher in black men and 1.5 kg/m2 higher in black women than in their white counterparts; when adjusted for covariates these differences were only of borderline statistical significance, however. CONCLUSIONS: Because of the wide range of BMI values associated with low risk, and the consistency of the point of the up-turn in risk, group specific definitions of optimal values do not appear to be warranted.

Adult↗
PubMed1997

Leptin concentration in women is influenced by regional distribution of adipose tissue.

Leptin concentrations in humans are increased with obesity, and women have higher leptin concentrations than men. This sex difference reflects the greater fat mass of women. However, there is evidence that factors other than the size of the adipose tissue mass contribute to serum leptin concentrations. This study was undertaken to determine whether anthropometric factors influenced leptin concentrations in our population. Leptin concentrations were measured in 375 persons from a population study of hypertension and diabetes for whom body-composition data (bio-electrical impedance analysis and anthropometry) were available. Serum leptin concentrations were more than four times higher in women than in men (18.5 +/- 13.9 compared with 3.8 +/- 3.6 ng/L, P < 0.0001). In individuals with comparable body mass indexes, these differences persisted after adjustment for either percentage fat (P < 0.05) or fat mass (P < 0.0001) by multivariate-regression analysis. After fat mass was adjusted for, the serum leptin concentration in both men and women was independent of waist circumference but in women was associated with hip circumference. Hip circumference is a proxy measure of peripheral fat and these results suggest that the larger hips of women may contribute to the sex difference in serum leptin concentration.

Adipose Tissue↗
PubMed1997

Relationship between blood pressure and body mass index in lean populations.

Associations between body mass index (BMI) and blood pressure (BP) have been consistently observed, but remain poorly understood. One unresolved question is whether there is a linear relationship across the entire BMI range. We investigated this question among 11,235 adult men and women from seven low-BMI populations in Africa and the Caribbean. We used kernel smoothing and multivariate linear and spline regression modeling to examine gender differences in the relationship and to test for a threshold. Age-adjusted slopes of BP on BMI were uniformly higher in men than women, with pooled slope ratios of 2.00 and 2.20 for systolic and diastolic BPs, respectively. Men displayed no evidence of age modification or nonlinearity in the relationship, and the age-adjusted slope of systolic BP on BMI was 0.90 (95% confidence interval [CI], 0.76 to 1.04). Women demonstrated both age modification and nonlinearity. For both younger (<45 years) and older (45+ years) women, the optimal change point for a single threshold model was found to be 21 kg/m2. Slopes of systolic BP on BMI above this threshold were positive and significant: 0.68 (95% CI, 0.54 to 0.81) and 0.53 (95% CI, 0.29 to 0.76) for younger and older women, respectively. Slopes below the threshold were essentially zero for both groups of women, and the difference between the slopes above and below the threshold was significant for younger women (P=.019). In summary, we observed a threshold at 21 kg/m2 in the relationship between BMI and BP for women but not for men. This contributes to the effort to identify the mechanisms that underlie this relationship and how they differ by gender.

Adult↗
PubMed1997

Prevalence of NIDDM among populations of the African diaspora.

OBJECTIVE: Rates of non-insulin-dependent diabetes mellitus have risen sharply in recent years among blacks in the U.S. and the U.K. Increases in risk have likewise been observed in the island nations of the Caribbean and in urban West Africa. To date, however, no systematic comparison of the geographic variation of NIDDM among black populations has been undertaken. RESEARCH DESIGN AND METHODS: In the course of an international collaborative study on cardiovascular disease, we used a standardized protocol to determine the rates of NIDDM and associated risk factors in populations of the African diaspora. Representative samples were drawn from sites in Nigeria, St. Lucia, Barbados, Jamaica, the United States, and the United Kingdom. A total of 4,823 individuals aged 25-74 years were recruited, all sites combined. RESULTS: In sharp contrast to a prevalence of 2% in Nigeria, age-adjusted prevalences of self-reported NIDDM were 9% in the Caribbean and 11% in the U.S. and the U.K. Mean BMI ranged from 22 kg/m2 among men in West Africa to 31 kg/m2 in women in the U.S. Disease prevalence across sites was essentially collinear with obesity, pointing to site differences in the balance between energy intake and expenditure as the primary determinant of differential NIDDM risk among these populations. CONCLUSIONS: In ethnic groups sharing a common genetic ancestry, these comparative data demonstrate the determining influence of changes in living conditions on the population risk of NIDDM.

Adult↗
PubMed1997

Lifestyle, education, and prevalence of hypertension in populations of African origin. Results from the International Collaborative Study on Hypertension in Blacks.

Lifestyle Incongruity has been shown to be associated with elevated blood pressure in various developing societies. We sought to test this model in an international collaborative study of hypertension in populations of African origin. Data were available for 4770 men and women, aged 25-74, from Africa, the Caribbean, and the United States. The main effects of lifestyle score (LSS) and education on hypertension prevalence were explored, as well as interactions predicted by the Lifestyle Incongruity model. Significant interactions were observed, but only the U.S. men conformed to the pattern predicted. For this group, adjusted ORs for LSS were 4.45 among low-education and 0.71 among high-education subgroups (risk OR = 0.16, 0.03-0.84 95% CI). The Lifestyle Incongruity model therefore received limited support. The model was designed to describe processes in societies experiencing modernization and opportunities for lifestyle differentiation, conditions that may not have been met in some sites.

Adult↗
PubMed1997

Prevalence of adult diabetes in Ibadan, Nigeria.

Within the framework of an international collaborative network, we measured the prevalence of diabetes mellitus in a traditional Yoruba community in the city of Ibadan, Nigeria. Using a random sampling technique we enrolled a community sample of 247 men and women. Fasting blood glucose (FBG) was measured at the community clinic from a fingerstick using the Companion2 Medisense blood glucose meter. The mean FBG was 4.7 mmol/L and 4.9 mmol/L for men and women, respectively. Using the 1985 WHO criteria, the prevalence of diabetes was 2.8%. There was no significant rise in FBG with age. Compared to the lowest quartile of the body mass index (BMI), there was about a 1.5 fold increased risk of developing elevated FBG. The test of trend between FBG and BMI was however not statistically significant. Despite a modest hypertension rate (22.3%), there was no significant difference in the FBG for hypertensives compared to normotensives. The findings of this study show that the prevalence of diabetes mellitus in this West African community remains low compared to nations in Western societies. However, in comparison to previous estimates from sub-Saharan Africa, the prevalence of adult onset diabetes seems to be on the increase.

Adult↗
PubMed1997

Socioeconomic status and health in blacks and whites: the problem of residual confounding and the resiliency of race.

A large number of epidemiologic studies have focused on racial/ethnic differences, particularly between blacks and whites. Because health endpoints and racial categorizations are associated with socioeconomic status, investigators generally adjust for socioeconomic indicators. The intention is usually to control for confounding, thereby making groups comparable and excluding socioeconomic status as an alternative explanation to hypotheses of innate physiologic differences. A threat to the validity of these analyses is therefore the presence of residual confounding. We identify four potential sources of residual confounding in this analytical design: categorization of socioeconomic status variables, measurement error in socioeconomic indicators, use of aggregated socioeconomic status measures, and incommensurate socioeconomic indicators. Using simulations and examples from the literature, we demonstrate that the effect of residual confounding is to bias interpretation of data toward the conclusion of independent racial/ethnic group effects. Investigators often refer to possible "genetic" differences on the basis of models that control for socioeconomic status. We propose that such conclusions on the basis of this analytical strategy are generally unwarranted. Racial/ethnic differences in disease are a pressing public health concern, but the current approach does not often provide a basis for inference about putative biological factors in the etiology of this disparity.

Black or African American↗
PubMed1997

The absence of adult mortality data for sub-Saharan Africa: a practical solution.

Information on cause of death among adults in sub-Saharan Africa is essentially nonexistent. Published sources provide statistics on both cause-specific and overall rates of mortality, but closer examination reveals that these data consist mostly of extrapolations and outright guesses. In the absence of accurate and comprehensive registries of vital events for the majority of the region's inhabitants, longitudinal studies of defined population-based cohorts represent the only realistic strategy to fill this void in basic public health information. The advantage of longitudinal studies is particularly clear for chronic diseases, the category for which the least is known. Noncommunicable diseases account for a significant portion of adult deaths in sub-Saharan Africa, yet the empirical bases for public health policies and interventions are essentially absent. Verbal autopsy has great potential to contribute to understanding about the cause of death among African adults. This method is discussed in the present article, and practical considerations for longitudinal studies using this methodology are reviewed.

Adolescent↗
PubMed1996

Determinants of hypertension in West Africa: contribution of anthropometric and dietary factors to urban-rural and socioeconomic gradients.

The determinants of hypertension in West Africa have not been well defined. The authors sampled 598 participants aged 45 years or more from a recent population-based survey in southwest Nigeria (190 rural men and women, 205 urban poor men and women, and 203 retired railway workmen). The estimated mean age was 61 (10) years. Mean pressures were low relative to westernized societies: systolic blood pressure = 124 (24) mmHg, diastolic blood pressure = 72 (13) mmHg. Both men and women were remarkably lean: body mass index = 21.3 (3.6) and 23.0 (5.2) kg/m2, respectively. Hypertension prevalence increased across the gradient from rural farmers to urban poor to railway workers: 14, 25, and 29 percent, respectively, had a blood pressure of 140/90 mmHg or greater, and 3, 11, and 14 percent, respectively, had a blood pressure of 160/95 mmHg or greater (p for trend < 0.01 for both cutpoints). On the basis of a 24-hour urine sample, daily electrolyte excretion was 110 (57) mEq of sodium and 46 (24) mEq of potassium. Mean sodium:potassium ratio was 2.6 (1.0) and was higher among the urban residents (p < 0.01) and correlated with systolic and diastolic pressures (r = 0.16-0.18, p < 0.01). These findings provide quantitative estimates of the impact of known hypertension risk factors in West Africa and demonstrate the basis for increased prevalence with urbanization and associated economic and dietary change. These results also provide support for recommendations for prevention in West Africa and provide a benchmark against which to compare populations in the African diaspora.

Aged↗
PubMed1996

Short stature and risk of mortality and cardiovascular disease: negative findings from the NHANES I epidemiologic follow-up study.

OBJECTIVES: This study sought to examine the relation between body height and incidence of myocardial infarction, coronary heart disease, overall mortality and mortality from cardiovascular disease. BACKGROUND: An association between short stature and increased risk of fatal and nonfatal cardiovascular disease has been observed in several studies, attracting considerable attention. METHODS: We used data from the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-Up Study, a prospective study of a large random sample of the U.S. population, to examine the association between height and risk of four end points. RESULTS: Baseline data were collected from 1971 to 1975 for 13,031 respondents (5,296 men, 7,735 women), and the average follow-up period was 13 years, through 1987. Height was inversely associated with risk of all four of the end points studied in both men and women. However, after adjustment for age and years of education in Cox proportional hazards analyses, the relation no longer existed. Using the same adjustment procedures, persons in the lowest height quintile had no increase in risk compared with those in the highest category. The findings were consistent for men and women, blacks and whites and different age groups. CONCLUSIONS: Data from this study in a national sample do not support the hypothesis of an inverse height-heart disease relation.

Adult↗