Search PubMed⌕ Search

Biomedical subjects

R S Cooper

Publications and source records attributed to R S Cooper.

At least 127 records · Page 7Linked to original sources
PubMed1995

Basal and stimulated platelet calcium and sodium in hypertensive versus normotensive black people.

To examine further the potential role of intracellular cations in hypertension a nested case-control study was carried out in conjunction with a population-based survey. Based on a house-to-house sampling scheme, 43 hypertensive and 56 normotensive black residents of Maywood, IL, were recruited. Free cytosolic calcium (Cai) and intracellular stores of calcium after stimulation with ionomycin were determined in platelets with the fluoroprobe Indo-I; intracellular sodium (Nai) measured at rest and after incubation with ouabain was estimated with SBFI. Cell sodium content was also assayed in erythrocytes. Resting Cai and Nai were not different in hypertensives compared with normotensives, although ionomycin-stimulated levels of Cai were correlated with systolic blood pressure (r = 0.3; P = 0.04). A consistent set of inter-relations among the various cation parameters was observed, lending support to the hypothesis that the cellular metabolism of sodium and calcium may be linked in the pathophysiological pathway to hypertension.

Adult↗
PubMed1994

Iron status and coronary heart disease: negative findings from the NHANES I epidemiologic follow-up study.

The potential association between iron status and coronary heart disease has received increased attention recently. The authors examine this hypothesis in the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study. The study consisted of 4,237 respondents (1,827 men, 2,410 women) aged 40-74 years at baseline. During the average 13-year follow-up, 489 persons (289 men, 200 women) had an acute myocardial infarction, and 1,151 persons (633 men, 518 women) developed coronary heart disease (included myocardial infarction and other forms of chronic ischemic heart disease). In logistic regression analyses, adjusting for baseline age, systolic blood pressure, serum cholesterol, smoking status, and education, serum iron was inversely associated with the risk of myocardial infarction in women (relative risk = 0.82 for an increase of 5.4 mumol/liter (equivalent to about 1 standard deviation), 95% confidence interval (CI) 0.70-0.95), but not in men. Total iron-binding capacity and transferrin saturation were not related to myocardial infarction in either sex, while serum iron and transferrin saturation were inversely associated with coronary heart disease in both sexes. Among men, the relative risk was 0.92 (95% CI 0.85-1.00) for a 5.4-mumol/liter increase in serum iron, while a relative risk of 0.91 (95% CI 0.83-1.00) was observed for a 10% increase in transferrin saturation. For women, the corresponding relative risks were 0.86 (95% CI 0.77-0.95) and 0.88 (95% CI 0.79-0.98), respectively. Dietary iron intake based on 24-hour recall was not associated with the two disease end points. These findings from a large national sample do not support the hypothesis of a positive iron-coronary heart disease relation.

Adult↗
PubMed1994

Factors related to the presence of microalbuminuria in essential hypertension.

The objective of the present study was to assess factors related to the presence of microalbuminuria in essential hypertension. Ninety-five patients with essential hypertension (58 males and 37 females, mean age 38.6 +/- 6.1 years) who had never been treated previously for hypertension were included in the study. Patients with nephropathy or diabetes mellitus, hyperglycemia > 120 mg/dL, glomerular filtration rate < 80 mL/min/1.73 m2, urinary tract infection, or positive dipstick for albumin or glucose were excluded. Blood pressure, echocardiographically determined left ventricular mass, serum biochemistry, and lipid profile were obtained. Twenty-four-hour urinary albumin excretion (UAE) was measured on two separate days using an immunonephelometric assay. Microalbuminuria (UAE 30 to 300 mg/24 h) occurred in 26% of patients and was associated with higher diastolic blood pressure (DBP), left ventricular mass index (LVMI), and a higher prevalence of hypertriglyceridemia and hyperapolipoproteinemia B (apo-B). Logistic regression analysis showed that the risk of microalbuminuria was independently related to diastolic blood pressure and hypertriglyceridemia when controlling for age, sex, body mass index, LVMI, and apo-B. Multiple regression analysis likewise confirmed that both DBP and LVMI were linearly related to UAE independent of age, sex, body mass index, total cholesterol, triglycerides, and apo-B. In conclusion, our study indicates that among hypertensive patients with elevated excretion rates of urinary albumin, even at the subclinical level, an increased cardiovascular risk exists compared to normoalbuminuric patients with a similar blood pressure. Assessment of the presence of microalbuminuria may be useful in the evaluation and management of hypertension.

Adult↗
PubMed1994

Ambulatory blood pressure monitoring in normotensive children.

OBJECTIVE: To assess reference values of ambulatory blood pressure in normotensive children. SUBJECTS AND DESIGN: Twenty-four-hour non-invasive ambulatory blood pressure monitoring (ABPM) was carried out in 241 healthy normotensive children aged from 6 to 16 years (126 boys, mean +/- SD age 11.2 +/- 2.7 years; 115 girls, mean +/- SD age 10.9 +/- 2.9 years). The subjects were subdivided into three age-sex groups: 6-9, 10-12 and 13-16 years. SETTING: Primary care. MAIN OUTCOME MEASURES: ABPM was performed using an oscillometric device (SpaceLabs model 90207) and appropriate cuff size during a regular school day. Blood pressure was measured every 20 min from 0600 to 2400 h, and thereafter every 30 min. At each monitoring session the following parameters were calculated for both systolic (SBP) and diastolic blood pressure (DBP): means and centiles for 24-h, daytime (0800-2200 h) and night-time (2400-0600 h); circadian variability, estimated as the blood pressure fall between the day and the night periods and the day: night ratio; and load, as the percentage of measurements above the age- and sex-specific 95th centile (P95). RESULTS: The upper limits of 'normality' for the mean of 24-h SBP and DBP estimated as the P95 in each age subgroup were 121/71 and 119/71 mmHg, 123/78 and 120/74 mmHg, and 124/78 and 125/75 mmHg, for boys and girls, respectively. A progressive increase in SBP with age was observed in both sexes, in contrast, DBP was similar throughout the age range. A nocturnal blood pressure fall of approximately 11 mmHg was observed for both SBP and DBP in all subgroups. The day:night ratio was 1.12 and 1.22 for SBP and DBP, respectively. The upper limit of blood pressure load, estimated as the P95 in all children, was 39% for SBP and 26% for DBP. A significant positive correlation was observed between casual blood pressure and 24-h ambulatory blood pressure (SBP: r = 0.61, P < 0.0001; DBP: r = 0.31, P < 0.0001). In general, mean ambulatory blood pressure, during the 24-h or the daytime period, was higher than casual blood pressure for both SBP and DBP. CONCLUSION: ABPM is feasible in children, and the values obtained are useful as a departure point in establishing reference values.

Adolescent↗
PubMed1994

Ambulatory blood pressure and microalbuminuria in essential hypertension: role of circadian variability.

OBJECTIVE: To assess the relationship of subclinical urinary albumin excretion with ambulatory and circadian variability of blood pressure. DESIGN AND METHODS: Patients with essential hypertension (82 males and 59 females, mean +/- SD age 38.9 +/- 7.3 years) who had never been previously treated for hypertension were included in the study. Patients with nephropathy or diabetes mellitus, hyperglycemia > 120 mg/dl, glomerular filtration rate < 80 ml/min per 1.73 m2, urinary tract infection and positive dipstick for albumin or glucose were excluded. Twenty-four-hour ambulatory blood pressure monitoring on a regular working day using an oscillometric device was performed. Twenty-four-hour urinary albumin excretion was measured on two separate days using an immunonephelometric assay. RESULTS: Microalbuminuric patients (urinary albumin excretion 30-300 mg/24 h, n = 31) had significantly higher mean ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) than those with normoalbuminuria (urinary albumin excretion < 30 mg/24 h, n = 96) during the 24-h, daytime (0800-2200 h) and night (2400-0600 h) periods, whereas for office blood pressure only DBP was significantly higher. Urinary albumin excretion was positively correlated with the means of SBP and DBP. Multiple regression analysis similarly confirmed that DBP during daytime was positively and day:night ratio of DBP inversely associated with urinary albumin excretion independent of age, sex and other parameters of ambulatory blood pressure. CONCLUSIONS: In conclusion, the present study indicates that, in middle-aged essential hypertensive patients, the presence of microalbuminuria is a marker for the presence of higher values of blood pressure throughout a 24-h period.

Adult↗
PubMed1994

Spectrum of hypertensive target organ damage in Africa: a review of published studies.

This paper reviews the evidence of hypertensive target organ damage (HTOD) in Africa, and the difficulties of its assessment, with a focus on implications for further research and prevention. Specific examples of HTOD reviewed include left ventricular hypertrophy, heart failure, ischaemic heart disease, arrhythmias and sudden death, kidney failure, cerebrovascular accidents, retinopathy and central as well as peripheral vascular disease. There is evidence that the prevalence of hypertension is increasing in some parts of Africa, thus increasing the number of people who suffer from fatal and nonfatal complications. Analysis of the type, frequency and distribution of HTOD is critical to the design of interventions to prevent and manage hypertension, and in the design of future clinical research. As would be expected, the frequency of atherosclerotic complications, particularly involving the heart, is lower in Africa than in developed countries. Stroke, renal failure and heart failure appear to be the principal adverse outcomes and are likely to be associated with a high case fatality rate. Community-based data on these issues are limited, however, and hospital series cannot estimate the population burden and may be unreliable in describing the case mix. Improved data on HTOD will more accurately reflect the health impact of hypertension, provide the basis for aggressive efforts at prevention, detection and control of high BP and establish their relevance in the overall scheme of resource allocation during fiscal austerity and limited healthcare spending. Additionally, knowledge of the prevalence and relative frequencies of HTOD has direct and important implications for clinical outcomes research in hypertension.

Africa↗
PubMed1993

Determinants of incident non-insulin-dependent diabetes mellitus among blacks and whites in a national sample. The NHANES I Epidemiologic Follow-up Study.

The excess incidence of non-insulin-dependent diabetes mellitus noted among African Americans in the past two decades may be attributable to variations in the distribution of specific risk factors, or the impact of these risk factors may differ by ethnicity or sex. Over the 16 years (1971-1987) of the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, 880 incident cases of diabetes mellitus developed among 11,097 white and black participants who were between the ages of 25 and 70 years at baseline. There were substantial differences among the four race/sex groups with respect to age at baseline, as well as marked differences in the distribution of several major risk factors for diabetes, including obesity, subscapular and triceps skinfold thickness, blood pressure, income, activity, and educational level. The age-adjusted incidence of diabetes over the course of the study was 15.0% among black women, while it was 10.9% among black men. White women and men experienced similar, more moderate risks of 7.0% and 6.9%, respectively. The 100% excess risk among black women and the 50% excess among black men can in large measure explain the recent marked increase in diabetes rates in the black community. Furthermore, at nearly every level of obesity, blacks had a higher risk of diabetes than whites, suggesting that other factors contributed to risk. A significant interaction between race and body mass index (weight (kg)/height(m)2) was likewise demonstrated in multivariate analysis. Baseline age, race, body mass index, and ratio of subscapular skinfold to triceps skinfold were significantly related to incident diabetes, both overall and in separate models for men and women; in the entire cohort and in women alone, blood pressure, activity level, and education also contributed to risk. Other interactions were tested but were not found to be important. Despite sampling difficulties and inconsistencies in the data, the NHANES I Epidemiologic Follow-up Study provides evidence that the associations of anthropometric and sociodemographic variables with diabetes may vary among subgroups which have different mean levels and distributions of these risk factors.

Adult↗
PubMed1993

Health and the social status of blacks in the United States.

Inequalities in health status among various racial and ethnic groups form a prominent chapter in the history of public health in the United States. Inequalities are observed for a wide range of specific conditions, and evolve over time. Little evidence is available to support the contention that any sizable proportion of this overall inequality is caused by genetic factors operating at the population level. On the other hand, social status, as measured by proxy variables like income and education, does provide important information about the black-white differential in health status when used in standard epidemiologic analyses. What is often neglected in these analyses, however, is an attempt to define underlying pathogenic mechanisms that incorporate social processes. Causal explanations based on the broader observation that inequality determined by the structure of social relations is associated with health differentials in all populations offer a plausible theoretic framework. At the same time, the unique character of the experience of specific ethnic subpopulations must be accounted for. Any attempt to account for the impact of race with greater precision will require an attempt to define this demographic variable within the context of social class relations.

Black People↗
PubMed1993

Sex differences in the impact of coexistent diabetes on survival in patients with coronary heart disease.

OBJECTIVE: To evaluate the sex difference in the impact of diabetes on survival in patients with coronary heart disease. RESEARCH DESIGN AND METHODS: Cohort study based on a sample from a hospital registry in Chicago, IL. A total of 974 consecutive patients (585 men and 389 women) with angiographically confirmed coronary artery disease were followed for 4.6 yr. RESULTS: At baseline, 160 men and 155 women had diabetes. The age-adjusted relative risk of death from all causes for patients with diabetes versus patients without diabetes was 0.93 (95% confidence interval 0.65-1.34) in men and 1.99 (95% CI 1.30-3.05) in women. For cardiac death, the corresponding relative risk was 1.00 (95% CI 0.64-1.56) and 1.96 (95% CI 1.19-3.24) in men and women, respectively. Baseline differences in age, hypertension, body mass index, number of diseased vessels, and ejection fraction did not fully explain the excess mortality risk in diabetic women. Excess risk was apparent in both cardiac and noncardiovascular categories. Among nondiabetic patients, the risk of death was significantly lower in women compared with men (multivariate-adjusted relative risk = 0.61, 95% CI 0.41-0.89). However, the mortality risk of diabetic women became similar to men as a whole (relative risk = 1.13, 95% CI 0.80-1.60). CONCLUSIONS: Diabetes confers a substantially higher risk of mortality in women than in men when it occurs in the presence of coronary heart disease.

Age Factors↗
PubMed1993

Establishing the epidemiologic basis for prevention of cardiovascular diseases in Africa.

A child born today in the rich countries of the world will inherit the expectation of living into the mid-70s. In Africa, of those surviving to the age of 5 years, the expectation of reaching the mid-50s remains in doubt. Inequality in the opportunity to experience life itself remains the cruelest inequality of all. As in many other fields, the technological experience accumulated by the economically wealthy countries can be put to useful purposes in underdeveloped regions. Given the longer history of chronic disease epidemiology in wealthy societies, much has been learned and many successes have been achieved. These lessons are, to a large extent, exportable. An opportunity to avoid the transition to high rates of CVDs and cancer therefore exists through implementation of primary prevention programs. Despite the competing priorities, a coordinated and sustained effort to achieve this goal should be initiated without further delay.

Adult↗
PubMed1993

Delay between onset of chest pain and arrival to the coronary care unit among minority and disadvantaged patients.

Prehospital delay is an important cause of out-of-hospital coronary mortality. To determine the effects of decision time delay in a patient population comprised mainly of blacks and the underprivileged, 74 consecutive patients with acute chest pain necessitating admission to the coronary care unit in a large urban hospital were studied. Delay time from onset of chest pain to the decision to seek medical care was markedly prolonged in patients with myocardial infarction (n = 24; mean time: 11.3 +/- 18 hours) as well as in patients with chest pain who did not develop myocardial infarction (n = 50; mean time: 20.5 +/- 26 hours). In addition, transfer time from the emergency room to the coronary care unit was likewise unduly long (mean time: 4 +/- 3.8 and 4.1 +/- 6 hours for patients with and without myocardial infarction, respectively). This study documents a significant delay in the decision time among patients with low socioeconomic status, mostly inner-city blacks, and in the transfer time from emergency room to the critical care unit in a large public hospital. These findings must be taken into consideration when planning strategies to improve the health-care delivery system to blacks and the underprivileged and further lend support to the practice of initiating thrombolytic therapy in the emergency room.

Black or African American↗
PubMed1992

The prognostic role of left ventricular hypertrophy in patients with or without coronary artery disease.

OBJECTIVE: To examine the association between echocardiographically determined left ventricular hypertrophy and mortality in patients with and without coronary artery disease. DESIGN: Cohort study with a mean follow-up period of 4 years. SETTING: An inner-city public hospital in Chicago. PATIENTS: A cohort of 785 patients, most of whom were black and had hypertension. INTERVENTIONS: Coronary arteriography for presumed coronary artery disease and echocardiography. MAIN OUTCOME MEASURE: All-cause and cardiac mortality. RESULTS: Left ventricular hypertrophy, based on left ventricular mass corrected for body surface area, was present in 194 of 381 patients (51%) with coronary artery disease and in 162 of 404 patients (40%) without coronary artery disease. Patients with left ventricular hypertrophy had worse survival than those without hypertrophy in both the group with coronary artery disease and the group without coronary artery disease. After adjustment was made for age at baseline, sex, and hypertension, the relative risk for death from any cause in patients with hypertrophy compared with patients without hypertrophy was 2.14 (95% CI, 1.24 to 3.68) among those with coronary artery disease and 4.14 (CI, 1.77 to 9.71) among those without coronary artery disease. CONCLUSIONS: Echocardiographically determined left ventricular hypertrophy is an important prognostic marker in patients with or without coronary artery disease. The effect of reversing ventricular hypertrophy in patients with and without coronary disease deserves further study.

Adult↗
PubMed1992

Survival rates with coronary artery disease for black women compared with black men.

OBJECTIVE: To evaluate the influence of gender on the prognosis of coronary heart disease among black patients. DESIGN: Cohort study based on a consecutive sample from a hospital registry, with a mean follow-up of 4 years. SETTING: An inner-city public hospital in Chicago, Ill. PATIENTS: The study included 1719 consecutive black patients (780 men and 939 women) who had any one of the following events: cardiac catheterization for presumed coronary heart disease, hospitalization for acute myocardial infarction, or coronary artery bypass grafting. RESULTS: Hospital and operative mortality rates following acute myocardial infarction and coronary artery bypass grafting were similar between the two sexes. The relative risks for cardiac death in women vs men were 0.88 (95% confidence interval [CI], 0.60 to 1.28), 0.79 (95% CI, 0.53 to 1.17), and 0.79 (95% CI, 0.34 to 1.85) for coronary artery disease, acute myocardial infarction, and coronary artery bypass grafting, respectively, after adjusting for age, history of diabetes, hypertension, angina pectoris and myocardial infarction, number of diseased vessels, and ejection fraction. Compared with patients of the same sex with normal angiograms, relative risk estimates were 5.0, 10.1, and 6.3 for women and were 1.8, 4.0, and 2.0 for men in the same three groups of patients, respectively. CONCLUSIONS: Survival with coronary artery disease in black women is similar to that observed in black men, but relative to members of the same sex without the disease, the prognosis for women is considerably worse than for men.

Black or African American↗
PubMed1992

Changes in pulmonary hemodynamics with aging in a predominantly hypertensive population.

The impact of aging on pulmonary hemodynamics was investigated in 322 patients who underwent right- and left-sided cardiac catheterization and echocardiographic examination, and were free of coronary disease, impaired left ventricular systolic function and left ventricular dilatation. Most of the patients were black (83%) and hypertensive (78%). Mean pulmonary artery pressures increased progressively with age: 16.7 +/- 4.6, 17.9 +/- 6.4 and 20.6 +/- 8.0 mm Hg for those aged less than 45 (n = 50), 45 to 64 (n = 238) and greater than or equal to 65 years (n = 34), respectively (p = 0.020). Pulmonary vascular resistance was 99 +/- 42, 116 +/- 62 and 160 +/- 68 dynes s cm-5, and the ratio of pulmonary to systemic vascular resistance was 78, 80 and 105%, respectively, for the 3 age groups (p less than 0.001). Along with these changes, a decrease in cardiac output and an increase in systolic blood pressure and systemic vascular resistance with age were noted. The effect of age on mean pulmonary artery pressure and pulmonary vascular resistance was statistically significant after adjustment for gender, smoking status, body weight, left ventricular hypertrophy, systolic blood pressure and systemic vascular resistance. Consideration should be given to age-related changes in the pulmonary circulation when defining physiologically normal values.

Aged↗