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Biomedical subjects

D Sparrow

Publications and source records attributed to D Sparrow.

At least 109 records · Page 6Linked to original sources
PubMed1987

Aging-associated changes in indices of thrombin generation and protein C activation in humans. Normative Aging Study.

In view of the known association of vascular disease with increasing age, we have conducted an analysis of hemostatic system activity with respect to perturbations induced by aging phenomena. We have utilized an immunochemical assay for prothrombin fragment F1 + 2 to quantify Factor Xa activity upon prothrombin in the plasma of 199 healthy males between the ages of 42 and 80. The levels of F1 + 2 in this population generally increased as a function of age (P less than 0.0001). The metabolic behavior of this marker was determined in 10 individuals greater than 65 yr of age with varying levels of F1 + 2, which ranged from 1.28 to 5.85 nM. The elevations in the concentration of this component were not due to diminished clearance of the fragment. Radio-immunoassays for fibrinopeptide A (FPA) and the protein C activation peptide (PCP) were subsequently employed to measure thrombin activity upon fibrinogen and thrombin-thrombomodulin activity upon protein C, respectively, in 82 members of this population ranging in age from 42 to 80. Significant positive correlations were again observed between increasing age and the level of F1 + 2 (P less than 0.0001) as well as FPA (P less than 0.01) and PCP (P less than 0.002). The results of this cross-sectional study indicate that many apparently normal males of increasing age with normal immunologic levels of antithrombin III and protein C exhibit a biochemical defect that denotes the presence of an acquired prethrombotic state.

Adult↗
PubMed1986

Relation of blood pressure measured in several positions to the subsequent development of systemic hypertension. The Normative Aging Study.

To assess the relation of initial blood pressure (BP) taken in sitting, supine and standing positions to subsequent development of systemic hypertension, 1,564 men were followed for an average of 6.6 years. The men were participants in the Normative Aging Study, a longitudinal study of aging initiated in 1963 at the Veterans Administration Outpatient Clinic in Boston. After controlling for sitting levels of systolic BP and diastolic BP in a Cox regression model, supine systolic BP was found to be a significant predictor of subsequent hypertension. This effect of position was not solely a result of decreases in measurement error associated with using additional BP measurements. Although the physiologic mechanism for the observed predictive influence of postural BP on the development of hypertension are unknown, these findings may have important influences on identifying subjects at risk and also providing insight into disease pathogenesis.

Adult↗
PubMed1986

The relationship of blood lead to blood pressure in a longitudinal study of working men.

The relationship of lead exposure to blood pressure has been examined in a longitudinal study of a cohort of 89 Boston, Massachusetts, policemen. At the baseline examination, subjects had a blood lead determination and three consecutive blood pressure measurements. Triplicate blood pressure measurements were also taken at years 3, 4, and 5. Multivariate analysis revealed that, after correction for previous systolic blood pressure, body mass index, age, and smoking, a high level of blood lead was a significant predictor of subsequent elevation of systolic pressure. Bootstrap simulations of these models provided supporting evidence for the observed associations. These data suggest that lead exposure can significantly affect systolic pressure.

Blood Pressure↗
PubMed1986

Body weight and coronary disease risk: patterns of risk factor change associated with long-term weight change. The Normative Aging Study.

Previous studies have suggested that excess body weight increases coronary disease risk by modification of the levels of other risk factors and in addition may contribute to overall risk independently. Few studies, however, have systematically characterized long-term change in risk factors with specific changes in overall weight while they have controlled for the effects of multiple potential confounders. Also, very little information is available on the differential impact of weight change on risk factor changes with advancing age. The present investigation used 15 years of longitudinal data collected on 1,396 men participating in the Veterans Administration Normative Aging Study in Boston, Massachusetts. Multiple regression analysis was used to predict change in each of eight putative coronary disease risk factors from change in weight and the interaction between weight change and age. These included blood pressure, serum cholesterol, triglycerides, fasting and two-hour postprandial blood glucose, uric acid, and forced vital capacity of the lungs. After controlling for initial levels of the risk factor, weight, age, and smoking status, change in weight remained a significant predictor of long-term change in each of the risk factors studied. In addition, the interaction between weight change and age was significant for fasting glucose, uric acid, and forced vital capacity, indicating that the effect of weight gain on uric acid and forced vital capacity was greater in younger men whereas the effect of weight gain on fasting glucose was greater in older men.

Adult↗
PubMed1986

Relationship of fat distribution to glucose tolerance. Results of computed tomography in male participants of the Normative Aging Study.

Computed tomography (CT) scanning was used to assess the relationship of glucose tolerance to fat distribution in men. Three cross sections [chest (including upper arms), abdomen, and thigh] were scanned in 41 men randomly selected from the Normative Aging Study, a longitudinal study of aging. Greater amounts of fat in the upper body and greater ratios of upper-body fat to lower-body fat were significantly correlated with higher 2-h serum glucose levels after adjustment for age and body mass index. In particular, intra-abdominal fat, a feature uniquely measured by CT, was a significant correlate of 2-h glucose. Largely parallel results were obtained when we compared a sample of male diabetic subjects (N = 8) with the male normal subjects from our random sample. This investigation demonstrates that body fat distribution, adjusted for overall degree of obesity, is a significant correlate of glucose tolerance even in a sample unselected for extremes of physique.

Abdomen↗
PubMed1985

The relationship of various indices of heart size on chest x-ray to the 10-year incidence of hypertension. The Normative Aging Study.

A total of 598 males (aged 30-74 years) who had baseline (1961-1970) chest radiography and baseline blood pressure less than 140/90 mmHg were observed prospectively for 10 years. Subjects were participants of the Normative Aging Study, a longitudinal study on aging initiated in 1961 at the Veterans Administration Outpatient Clinic in Boston, Massachusetts. Blood pressures were taken at five- and 10-year follow-up examinations. Multiple logistic regression analysis indicated that the long diameter of the heart (on posteroanterior film) and the cardiac depth (on lateral film) were statistically significant predictors of subsequent hypertension after controlling for baseline body mass index, systolic pressure, and diastolic pressure. A similar model considering various composite indices of heart size indicated that the heart volume was a statistically significant and independent predictor of hypertension. Thus, increases in heart size may precede and predict the development of sustained hypertension.

Adult↗
PubMed1984

Trace metals in drinking water: lack of influence on blood pressure.

It has been suggested that certain trace metals may affect human blood pressure. We recently measured trace metals in the tapwater from the homes of 246 male participants of the Normative Aging Study. Participants were free of any disease or medication known to influence blood pressure. No statistically significant relationship was found between lead concentration and systolic blood pressure in an analysis of covariance, controlling for age and body mass index. Diastolic pressure was examined as well and the results were almost identical. Since educational level and town of residence were potential confounders, we stratified on these variables but no association between lead concentration and blood pressure emerged. Similarly, no statistically significant relationships were found between blood pressure and copper or iron. Blood pressure did differ significantly among zinc concentration groups but no uniform trend appeared. In light of evidence from other studies suggesting that blood pressure is influenced by lead or other elements in drinking water, further investigations with more highly exposed subjects or a prospective design appear warranted.

Adult↗
PubMed1984

Change in blood pressure and total cholesterol with retirement.

This study examines change in systolic blood pressure, diastolic blood pressure, and total serum cholesterol over a three-year span in two groups of men aged 55-74 years at follow-up: 1) 262 men who were working at baseline but retired at follow-up, and 2) 409 age peers who remained employed at both measurement times. Measures were obtained from medical examinations conducted since the early 1970s as part of the prospective Veterans Administration Normative Aging Study in Boston. Regression analyses showed an average increase of 3.44 mmHg in systolic blood pressure, 1.62 mmHg in diastolic blood pressure, and 5.56 mg/dl in cholesterol for retirees compared with workers. The relative increases in the blood pressure variables were statistically significant. However, a logistic regression analysis did not show a greater incidence of hypertension among retirees compared with workers. The odds ratio, standardized for baseline blood pressure, body mass index, and age, was 0.90 (95 per cent confidence interval 0.56-1.45). Among retirees only, analyses of covariance showed that levels of blood pressure and cholesterol were comparable from one six-month interval to the next in the three years preceding and following retirement. Overall, the effects of retirement were not of sufficient magnitude to conclude that retirement had a clinically significant impact on blood pressure or cholesterol.

Aged↗
PubMed1984

Postural changes in diastolic blood pressure and the risk of myocardial infarction: the Normative Aging Study.

To assess the relationship of postural changes in blood pressure to risk of myocardial infarction, 1359 men were followed for an average of 8.7 years. The men were participants in the Normative Aging Study, a longitudinal study of aging initiated in 1963 at the Veterans Administration Outpatient Clinic in Boston. It was found that the relationship of sitting blood pressure to the subsequent incidence of myocardial infarction was modified by a variable formed by subtracting supine from standing diastolic blood pressure (delta DBP). The effect of sitting diastolic blood pressure on risk of myocardial infarction was confined primarily to men with a delta DBP of 10 mm Hg or more. The effect of sitting systolic blood pressure on risk of myocardial infarction was apparent in all categories of delta DBP (less than 1, 1 to 9, greater than or equal to 10 mm Hg), but the gradient of risk became stronger with increasing levels of delta DBP. The modifying influence of delta DBP remained even when standard coronary risk factors were included in multivariate analyses. These findings suggest a relationship of vascular responsiveness to risk of subsequent myocardial infarction and may have clinical utility.

Adult↗
PubMed1984

The relationship of the peripheral leukocyte count and cigarette smoking to pulmonary function among adult men.

The relationship of the peripheral leukocyte count to pulmonary function was examined in 1,510 men. There were 466 current cigarette smokers, 485 former cigarette smokers, and 559 never smokers enrolled in a longitudinal study of aging. Spirometry was performed twice on all subjects ten years apart. A multiple regression analysis indicated that leukocyte count was inversely related to baseline levels of both forced vital capacity (FVC) (p less than 0.001) and forced expiratory volume in one second (FEV1) (p less than 0.001) after adjustment for age, height, and smoking habits. Similarly, change in leukocyte count over a ten-year period was inversely related to follow-up levels of both FVC (p = 0.036) and FEV1 (p = 0.004) after adjustment for baseline levels of leukocyte count, pulmonary function, age, height, and smoking habits. These data suggest that the peripheral leukocyte count is an important determinant of level of pulmonary function. Further investigation of the pathophysiologic mechanisms involved in this association seems indicated.

Adult↗
PubMed1983

The relationship of the baseline ECG to blood pressure change.

A total of 1,090 male participants (aged 23 to 80 years) of the Normative Aging Study who had baseline BP less than 140/90 mm Hg were observed prospectively for ten years. Blood pressures were taken at five- and ten-year follow-up examinations. Multiple linear regression analysis indicated that baseline levels of systolic pressure, age, R-wave amplitude (aVL), hematocrit, T-wave amplitude (V5), and S-wave amplitude (V4, V5, and V6) were statistically significant predictors of systolic pressure change. Baseline levels of diastolic pressure, R-wave amplitude (aVL), and hematocrit were statistically significant predictors of diastolic pressure change. Multiple logistic regression analysis showed that baseline levels of BP, S-wave amplitude (V1, V2, and V3), body mass index, R-wave amplitude (V4, V5, and V6), and T-wave amplitude (V5) were statistically significant predictors of subsequent hypertension. Whether the identified ECG amplitudes are an indicator of early increases in peripheral resistance or a function of neurohumoral factors, or both, is unknown.

Adult↗
PubMed1983

The relationship of the U wave to the 10-year incidence of myocardial infarction.

The relationship between the baseline electrocardiogram and 10-year incidence of myocardial infarction was examined in a cohort of 1013 men. The men were participants in the Normative Aging Study, a longitudinal study of aging initiated in 1963 at the Veterans Administration Outpatient Clinic in Boston, Massachusetts. Absence of the U wave among these men yielded a relative risk estimate of myocardial infarction of 2.7 as compared to men with a U wave present (95% confidence interval, 1.4-5.2). This association persisted when standard coronary risk factors (cholesterol, blood pressure, and cigarette smoking) were taken into consideration in a multivariate analysis. The results support the conclusion that an abnormality in the electrocardiogram considered to be of little importance indicates an increased risk of myocardial infarction independent of known coronary risk factors.

Adult↗
PubMed1983

Coronary heart disease in police officers participating in the Normative Aging Study.

There is evidence suggesting that male police officers are at a higher risk of developing coronary heart disease than males in the general population. Thus, 1648 men (including 220 police officers and 1428 non-police officers) were followed for 10 years to determine the incidence of coronary heart disease. Subjects were participants of the Normative Aging Study, a longitudinal study of aging initiated in 1963 at the Veterans Administration Outpatient Clinic in Boston, Massachusetts. Comparison of police officers and non-police officers showed no statistically significant differences in the crude incidence rates of coronary heart disease (myocardial infarction, angina pectoris, or death from coronary heart disease) and myocardial infarction alone. When baseline age, serum cholesterol, blood pressure, cigarette smoking, and body mass index were taken into consideration in multiple logistic regression analyses, the lack of significant differences between groups persisted. Police officers relative to non-police officers had an adjusted risk ratio (odds ratio) of 1.4 (95% confidence interval = 0.7-2.4) for coronary heart disease and 1.0 (95% confidence interval = 0.4-2.4) for myocardial infarction. Differences between occupational groups were not statistically significant.

Adult↗
PubMed1983

The relationship of tar content to decline in pulmonary function in cigarette smokers.

The impact of the tar content of cigarettes on pulmonary function was examined in 1,355 men. These men represented 383 current cigarette smokers, 555 former cigarette smokers, and 417 never smokers enrolled in longitudinal study of aging. Current smokers' cigarette exposure was estimated by the number of cigarettes smoked per day and tar content per cigarette. spirometry was performed twice on all subjects at a 5-yr interval. A multiple regression analysis indicated that tar content did not significantly influence baseline levels of forced vital capacity (FVC) or forced expiratory volume in one second (FEV1), after controlling for age, height, and number of cigarettes smoked. Similarly, tar content did not significantly influence follow-up levels of FVC or FEV1, after controlling for age, height, number of cigarettes, and baseline pulmonary function. These data suggest that low tar cigarettes may not protect smokers from an increased rate of decline in pulmonary function.

Adult↗
PubMed1983

Alcohol consumption and pulmonary function. A cross-sectional and longitudinal study.

The impact of alcohol consumption on pulmonary function was examined in 1,067 men. Subjects were classified according to their average weekly alcohol consumption, and spirometry was performed twice on all subjects over a 5-year interval. A multiple regression analysis indicated that alcohol consumption did not significantly influence baseline levels of forced vital capacity (FVC) or forced expiratory volume in one second (FEV1) after controlling for age, height, cigarette smoking habits, and educational attainment. Similarly, alcohol consumption did not significantly influence follow-up levels of FVC or FEV1 after controlling for age, height, cigarette smoking habits, educational attainment, and baseline pulmonary function. Although these results do not rule out a possible independent effect of alcohol on pulmonary function, any such effect would be relatively small.

Adult↗
PubMed1983

Asbestos exposure correlates with alterations in circulating T cell subsets.

Peripheral blood lymphocytes were analysed from 40 subjects with occupational asbestos exposure and 40 controls matched for age and smoking habits. Patients were classified by duration of exposure as short or long, and by chest radiograph as normal, pleural plaques or interstitial changes. As a group, subjects with asbestos exposure had decreased percentages of OKT3+ and OKT8+ cells and increased OKT4+/OKT8+ ratio compared to controls. Correcting for age and smoking, those with short exposure were similar to controls, while those with long exposure had decreased percentages OKT3+ and OKT8+ cells and an increased OKT4+/OKT8+ ratio. Among radiographic subgroups, those with normal radiographs were similar to controls, but those with plaques had increased circulating OKT4+ cells, and those with interstitial changes had decreased percentages OKT3+ and OKT8+ cells and OKT8+ cells/mm3, with an increased OKT4+/OKT8+ ratio. There were no differences between subjects and controls in OKT10+ cells and OKIa+ cells. There appears to be a progressive decrease in percentage OKT8+ cells and increase in OKT4+/OKT8+ ratio with increasing exposure to asbestos, as determined by length of exposure and by radiographic abnormalities.

Antibodies, Monoclonal↗
PubMed1982

Effect of age on insulin stimulation of sympathetic nervous system activity in man.

Previous studies have shown that oral glucose increases plasma norepinephrine (NE) in man, an effect which is more pronounced in the elderly. Recently we have shown that hyperinsulinemia results in a dose-dependent increase in sympathetic nervous system (SNS) activity in young men independent of changes in blood glucose. We now report studies of the influence of hyperinsulinemia on SNS activity in healthy elderly. Euglycemic glucose clamp studies were performed at 2 insulin infusion rates, 2 mU/kg/min (young 22-37 yr, n = 7; old 63-77 yr, n = 9) and 5 mU/kg/min (young 22-36 yr, n = 7; old 64-75 yr, n = 5) nonobese men. Control studies were performed in 5 young and 3 old subjects. In control studies there were no significant changes in NE or cardiovascular measures in either group. Insulin infusion at 2 mU/kg/min in young subjects were associated with significant increases in NE, (p less than 0.001) pulse (p less than 0.05), pulse pressure (p less than 0.005) and double product (pulse x systolic pressure) (p less than 0.01). In contrast 2 mU/kg/min insulin infusion in the elderly did not result in an increase in NE, and cardiovascular changes were limited to an increase in pulse pressure (p less than 0.01). The changes in NE at this insulin infusion dose were greater in the young than in the old (p less than 0.005). Insulin infusion at 5 mU/kg/min in young subjects were associated with significant increases in NE, (p less than 0.001) mean arterial blood pressure (MABP) (p less than 0.001), pulse pressure (p less than 0.001) and double product (p less than 0.001). In contrast 5 mU/kg/min insulin infusion in the elderly did not result in an increase in NE, and cardiovascular changes were limited to a decrease in MABP (p less than 0.001) only. The change in NE and MABP at this insulin infusion dose were greater in the young than in the old (p less than 0.001) for each). In the young group the increases in NE were greater during the 2 mU/kg/min studies than in the control studies (p less than 0.001) and the increases in NE during the 5 mU/kg/min studies were greater than during the 2 mU/kg/min studies (p less than 0.001). In the old group there were no differences in NE or cardiovascular measures between the control, 2 mU or 5 mU insulin infusions. These studies indicate diminished insulin-induced SNS activation in the elderly. The disparity in the elderly between the enhanced SNS response to oral glucose and the blunted response to intravenous insulin and glucose suggests that splanchnic factors may mediate the SNS activation after oral glucose.

Adult↗