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Biomedical subjects

W L Haskell

Publications and source records attributed to W L Haskell.

At least 145 records · Page 8Linked to original sources
PubMed1984

Indirect measures of cigarette use: expired-air carbon monoxide versus plasma thiocyanate.

Indirect, biochemical measures of cigarette use are valuable in confirming smoking status in both cross-sectional and cessation studies. This study compares two such biochemical markers, expired-air carbon monoxide (CO) and plasma thiocyanate (SCN), in a representative population sample of 2,237 adults (ages 18-74) from the baseline survey of the Stanford Five City Project. CO and SCN are both significantly higher in self-reported smokers than in nonsmokers and correlate well with number of cigarettes smoked per day. CO appears to be more sensitive and specific than SCN in comparison to self-report, and CO misclassifies a significantly smaller number of nonsmokers, regular smokers, and light smokers (less than 9 cigarettes per day) than does SCN. Together, CO and SCN better classify smokers and nonsmokers than do either alone. Neither biochemical is a reliable indicator in irregular smokers (no cigarettes in past 48 hr). Despite its much shorter metabolic half-life, CO is a better indicator of cigarette use than is SCN in this cross-sectional study. CO is generally simpler and less expensive to measure than is SCN, and CO may be a preferable indirect measure of smoking status in some studies of smoking cessation.

Adolescent↗
PubMed1984

Seven-day activity and self-report compared to a direct measure of physical activity.

To determine how well a seven-day interview-administered activity recall used in a large epidemiologic study at Stanford University reflected seven days of self-reported activity and directly measured physical activity, 30 white males, mean age 52 years, recorded daily physical activity for a week, and half of these wore an ambulatory solid-state minicomputer (Vitalog) which measures continuous heart rate and motion. Total hours of moderate, hard, and hard plus very hard activity were not significantly different for weekdays and weekends for self-report and recall and were significantly correlated. Total energy expenditure for subjects wearing the Vitalog averaged 38.5 +/- 6.7 kcal/kg/day compared to an average of 37.7 +/- 4.5 kcal/kg/day for recall or 39.6 +/- 7.2 kcal/kg/day for self-report. Conditioning activities are best remembered followed by home or leisure and job activities. Mean hours of sleep per week night were significantly greater reported by self-report than reported by recall, but the two were significantly correlated. It is concluded that a seven-day activity recall accurately reflects mean kcal/day expenditure, with conditioning activities being the best recalled. A self-report log used in conjunction with an interview-based seven-day recall might maximize accuracy of recall.

Adult↗
PubMed1984

Home versus group exercise training for increasing functional capacity after myocardial infarction.

To evaluate the efficacy of exercise training for increasing functional capacity in the 6 months after clinically uncomplicated myocardial infarction, 198 men 52 +/- 9 years of age participated in a training study. They were randomly assigned to one of four exercise protocols: 8 to 26 weeks of training at home (group 1, n = 66) or in a group program (group 2, n = 61) following treadmill testing performed 3 weeks after infarction, treadmill testing at 3 weeks without subsequent training (group 3, n = 34), and treadmill testing for the first time at 26 weeks (control, n = 37). At 26 weeks functional capacity was significantly higher in patients training at home or in a group program than that in patients without training or in control patients: 8.1 +/- 1.5, 8.5 +/- 1.3, 7.5 +/- 1.8, and 7.0 +/- 1.7 METs, respectively (p less than .05 and p less than .001). No significant differences in functional capacity were noted between patients training at home and those in a group program. No training-related complications occurred. Home and group training are equally effective in increasing functional capacity of low-risk patients after myocardial infarction.

Aged↗
PubMed1984

The influence of exercise on the concentrations of triglyceride and cholesterol in human plasma.

Exercise exerts both acute and chronic effects on plasma lipid and lipoprotein concentrations. Much of the triglyceride-lowering effect is an acute response, with the changes in cholesterol having a greater chronic component. The acute Tg decrease seems to be due to accelerated catabolism resulting from increased LPL activity. Following exercise, and on a more chronic basis, decreased VLDL-Tg synthesis may also occur in response to an increase in tissue insulin sensitivity. The low body fat content of endurance-trained athletes also contributes to lower Tg concentrations, through this same mechanism. The magnitude of the plasma Tg response to acute or chronic exercise is highly influenced by preexercise values--decreases in plasma Tg occur only when preexercise values are elevated. The major exercise effect on plasma cholesterol appears to be an increase in HDL-C as a result of endurance training, very likely related to the increase in LPL activity and Tg catabolism. This response is not always achieved with exercise training, and has been especially difficult to demonstrate in previously sedentary women. Exercise effects on HDL-C may be augmented by weight loss or changes in nutrient intake, but these interrelationships are not well established. A dose-response relationship exists, with the lower threshold influenced by baseline HDL-C values and exercise status. The higher HDL-C associated with endurance training is the result of increases in the less dense HDL2 subfraction, with elevations in both the lipid and protein components. Relatively small decreases in LDL-C occur with training. The biological mechanisms for these exercise effects have not been established.

Adolescent↗
PubMed1984

Safety of outpatient cardiac exercise programs. Issues regarding medical supervision.

Medical supervision of cardiac exercise programs should be individualized to each patient's needs. In order for this to be done, several factors must be considered, including the nature of increased risk during exercise due to coronary heart disease, ways to minimize the risk of cardiovascular complications during exercise, the types of medical supervision available and their contributions to safety, and the other factors that are influenced by medical supervision, such as program availability and cost and patient reactivity and compliance.

Ambulatory Care↗
PubMed1983

Growth and tissue abnormalities in young people with cyanotic congenital heart disease receiving systemic-pulmonary artery shunts.

The effects of systemic-pulmonary artery shunts on growth, body composition, and adipose tissue were studied in 29 children, aged 2 to 16 years, with cyanotic congenital heart disease. Of these, 16 received surgical shunts and 13 were unoperated. Postoperatively, all patients who received shunts were better oxygenated (systemic oxygen saturation 69 +/- 11% preoperatively and 84 +/- 4% postoperatively; mean +/- standard error of the mean) and were symptomatically improved. However, the groups were not significantly different in height, weight, lean body mass, total body fat, lean/fat ratio, cellular lipid content, or total number of lipid-containing fat cells. Age at operation did not seem to influence the effects of surgery. These observations suggest that growth and certain measurements of tissue development were unaffected by surgical systemic-pulmonary artery shunts despite increased oxygenation and symptomatic improvement after operation.

Adipose Tissue↗
PubMed1983

Does weight loss cause the exercise-induced increase in plasma high density lipoproteins?

Studies showing an increase in plasma concentration of high density lipoprotein cholesterol (HDL-C) with moderate exercise have usually rejected the role of body weight change in the HDL-C raising process, ostensibly because the amount of weight lost has been negligible. To investigate HDL-C changes more thoroughly, we followed initially sedentary middle-aged men randomly assigned to either a moderate running (n = 36) or a sedentary control (n = 28) group for one year. Among runners, one-year changes in plasma HDL-C concentrations correlated strongly with their body weight changes (r = - 0.53, P less than 0.001). Curve-fitting procedures and regression analysis suggested that processes associated with weight change produce much of the plasma HDL-C changes induced by moderate exercise and that changes in HDL-C concentration predominantly reflect changes in the reputedly anti-atherogenic HDL2 sub-component. Further, the interaction between weight change and plasma HDL-C concentration was significantly different (P less than 0.001) in exercisers and controls suggesting that the metabolic consequences of exercise-induced weight change are different from the consequences of weight change in the sedentary state.

Adult↗
PubMed1983

Increased exercise level and plasma lipoprotein concentrations: a one-year, randomized, controlled study in sedentary, middle-aged men.

Eighty-one sedentary but healthy men aged 30-55 participated in a 1 yr randomized study of the effects of exercise on plasma lipoprotein concentrations. Forty-eight were assigned to a running program, while 33 remained as sedentary controls (an approximately 3:2 ratio). After 1 yr the running group had become significantly fitter and leaner than the control group. Lipoprotein concentration changes in the runners (vs. controls) uniformly favored reduced risk of coronary heart disease, but were not significant when all 46 participants with complete data were included. However, the 25 men who averaged at least eight miles (12.9 kilometers) per wk of running increased their plasma high-density-lipoprotein (HDL) cholesterol level by 4.4 mg/dl (p = 0.045) and their HDL2 mass level by 33 mg/dl (p = 0.059), vs. controls. Significant correlations were found for distance run per wk vs. change in plasma HDL-cholesterol (r = 0.48), HDL2 (r = 0.41), and low-density-lipoprotein cholesterol (r = -0.31). Changes in percent body fat and in HDL-cholesterol were correlated (r = -0.47) in runners. There appears to be a threshold at about 8 miles per wk above which a 1-yr running program leads to beneficial lipoprotein changes.

Adult↗
PubMed1983

The association of blood pressure and dietary alcohol: differences by age, sex, and estrogen use.

This paper presents the results of an analysis of dietary alcohol use and blood pressure in representative population samples from four northern California cities surveyed in 1979-1980 as part of the Stanford Five City Project. The pooled samples included 883 men and 959 women aged 20-74 who were not taking blood pressure medications. Blood pressure was obtained while seated using a standard manometer. Alcohol was assessed by self-report of usual intake. In men, age-specific analysis revealed a positive association between dietary alcohol and both systolic (SBP) and diastolic blood pressure (DBP). The association was linear in men aged 20-34 and 50-74 and was stronger in the oldest men. Both linear and quadratic terms were significant for men aged 35-49. This association remained significant in a linear regression model that included age, relative weight, income, education, physical activity, cigarette use, and untimed urinary sodium/creatinine; for alcohol in ml/day in men aged 50-74, beta = 0.21, p = 0.0001, R2 = 0.32 for SBP; beta = 0.09, p = 0.0002, R2 = 0.18 for DBP. In women, alcohol use was significantly associated with blood pressure only in those above age 49 and was more striking in those not taking estrogens; this association was also independent of the same variables listed above for men (beta = 0.43, p = 0.0001, R2 = 0.23 for SBP; beta = 0.17, p = 0.001, R2 = 0.13 for DBP). Multiple logistic analyses with hypertension as a dichotomous dependent variable and including all subjects showed similar results. These results could be due to any one or more of the following hypotheses: 1) a biologic response to alcohol in older men and in older women that is different from the response in younger persons; 2) a delayed effect of alcohol use on blood pressure; 3) effects of a different pattern of alcohol use in the different age groups; or 4) the presence of some unmeasured confounding factor in the older age groups.

Adolescent↗
PubMed1983

Predictors of systolic blood pressure response to treadmill exercise: the Lipid Research Clinics Program Prevalence Study.

We used multiple linear regression to study predictors of systolic blood pressure response (SBPR), i.e., the increase in pressure above baseline after 3, 6, and 9 min of treadmill exercise, in 4262 men and women. Predictors considered were usual SBP, the difference (delta SBP) between resting SBP and SBP immediately before exercise, age, education, obesity index, alcohol consumption, cigarette smoking, preexercise heart rate and, in women, gonadal hormone use. In men, age, obesity index, and cigarette smoking were positively associated with SBPR and in women 20 to 49 years old, age, obesity index, and alcohol consumption were positively associated with SBPR. In women 50 years old or older, usual SBP was negatively associated with SBPR. In both men and women a larger delta SBP was associated with a smaller SBPR. These results help explain the considerable variation in SBPR, and the delta SBP results suggest that potential SBPR may, to certain extent, have a specific, finite range. The similarity of predictor variables for SBPR to predictor variables for hypertension is concordant with the previous observation that a high SBPR may foreshadow subsequent hypertension.

Adult↗
PubMed1983

Demonstration of a relationship between level of physical training and insulin-stimulated glucose utilization in normal humans.

The relationship between level of physical training and in vivo insulin-stimulated glucose utilization was investigated in 33 healthy nonobese subjects. Status of physical training was estimated by maximal oxygen consumption (VO2 max) during graded bicycle ergometry, and insulin action by the insulin clamp technique. Within the study population we defined a significant (r = 0.63, P less than 0.001) correlation between these two variables. This relationship was independent of age and obesity and accounted for over 40% of the variance in insulin-stimulated glucose utilization among these subjects. In addition, significant correlations existed between VO2 max and the plasma glucose (r = -0.35, P less than 0.05) and insulin (r = -0.37, P less than 0.05) responses to an oral glucose load. These results suggest that differences in level of physical training play a regulatory role in control of in vivo insulin action.

Adult↗
PubMed1982

The effects of running mileage and duration on plasma lipoprotein levels.

Eighty-one healthy, sedentary men aged 30 to 55 years were randomly assigned to supervised running (n = 48) or to sedentary control groups (n = 33) and followed up in a one-year trial. Measurements of plasma lipoproteins, fitness, and percent body fat were made at three-month intervals. Results and conclusions from this study are (1) that cross-sectional studies of lipoprotein concentrations in exercisers may be biased by a self-selection effect, since study participants with initially higher high-density lipoprotein cholesterol (HDL-C) and lower triglyceride concentrations were more easily persuaded to run more miles; (2) that plasma concentrations of HDL-C and low-density lipoprotein cholesterol (LDL-C) generally did not begin to change until a threshold exercise level (ten miles run per week) was maintained for at least nine months; and (3) that fitness increased and percent body fat decreased sooner and at lower exercise levels than required for HDL-C and LDL-C concentration changes.

Adipose Tissue↗
PubMed1982

Factors influencing estimated oxygen uptake during exercise testing soon after myocardial infarction.

To determine the extent to which oxygen uptake (VO2) estimated from exercise testing in healthy adults is applicable to patients tested soon after myocardial infarction, VO2 was measured during symptom-limited treadmill testing 3 and 11 weeks after the acute event. Twenty-two men (Group I) underwent treadmill testing using a "standard" modified Balke protocol (3 miles/h [80 m/min] with 2.5 percent increments in grade every 3 minutes) 3 and 11 weeks after infarction. Twenty-five clinically similar men (Group II) underwent treadmill testing using a standard protocol at 3 weeks but an "accelerated" protocol (3 miles/h with 5 percent increments in grade every 3 minutes) at 11 weeks. Measured and estimated values of peak VO2 were nearly identical for both groups of patients performing the standard protocol at 2 weeks (mean +/- standard deviation 20.5 +/- 4.7 versus 20.4 +/- 6.1 and 22.1 +/0 4.1 versus 22.5 +/- 4.5 ml/kg per min for Groups I and II, respectively). Measured and estimated values of peak VO2 were also similar for patients completing the standard protocol at 11 weeks (26.3 +/- 7.6 versus 26.7 +/- 6.9 ml/kg per min). In contrast, estimated values of peak VO2 were significantly higher than measured values in patients completing the accelerated protocol at 11 weeks (30.8 +/- 4.3 versus 27.7 +/- 5.0 ml/kg per min (probability [p] = 0.001). Holding onto the treadmill handrails significantly increased estimated peak VO2 (32.7 to 37.9 ml/kg per min) but did not affect measured peak VO2 (32.1 to 31.8 ml/kg per min). These results indicate that VO2 for patients performing treadmill exercise testing after myocardial infarction can be estimated from data derived from healthy adults so long as the exercise intensity is increased slowly and holding onto the handrails is avoided.

Aged↗
PubMed1982

Association arrays for the study of familial height, weight, lipid, and lipoprotein similarity in three West Coast populations.

A more refined understanding of familial similarity may be achieved through a collection of measures of dependence that is sensitive to a variety of nonlinear trends ans stochastic relationships between trait values. Parent-offspring, spouse, and sibling similarities are examined by association arrays that assess dependence between variables for appropriate classes of functions (e.g., the class of all increasing functions). The methodology is applied to height, weight, lipid, and lipoprotein variables collected in nuclear families at the Seattle, Stanford, and La Jolla Lipid Research Clinics. Among the results obtained using association arrays, there is the suggestion that spouse similarity for standardized weight is strongest for functions emphasizing the higher values of the wives' weight independent of the husbands' weight, and that sibling similarity for high density lipoprotein cholesterol concentrations appears strongest for functions emphasizing the higher values of the siblings. The results deduced from the method of association arrays are compared and contrasted with those obtained from standard correlations.

Adolescent↗
PubMed1982

Autonomic contribution to heart rate recovery from exercise in humans.

To assess the contribution of the autonomic nervous system to heart rate recovery following exertion, heart rate was observed after peak treadmill exercise in six men following parasympathetic blockade (PB) with atropine sulfate (0.03 mg/kg), sympathetic blockade (SB) with propranolol hydrochloride (0.20 mg/kg), double blockade (DB) with both drugs, and no drugs (ND). Least-squares analysis of each subject's heart rate (HR) as an exponential function of recovery time (t) was computed for each treatment giving an equation of the form HR = aebt. HRs at rest, peak exercise, and 10 min of recovery, the coefficients a and b, and the least-squares correlation coefficient (r) were compared among treatments by nonparametric analysis of variance and rank-sum multiple comparisons. HR recovered in an exponential manner after dynamic exercise in each subject with each of the treatment modes (P less than 0.01 for each r, mean across all treatments r = 0.94). Coefficients a and b differed the most between PB and SB. At the cessation of exercise the decreases in venous return and the systemic need for cardiac output are accompanied by an exponential HR decline. The exponential character of the cardiodeceleration seen after peak exercise appears to be an intrinsic property of the circulation because it occurred under each experimental condition.

Adult↗
PubMed1981

Effect of health education on dietary behavior: the Stanford Three Community Study.

A 2-yr mass media cardiovascular health education program in two communities was followed by a 3rd, maintenance yr of reduced effort. In each community, a representative cohort reported its dietary behavior annually to an interviewer using a questionnaire which estimated daily consumption of cholesterol and fat. Relative weight and plasma cholesterol were also measured annually. Both men and women in the treatment towns reported reductions in dietary cholesterol (23 to 34%) and saturated fat (25 to 30%) which were significantly larger than those reported in a 3rd, control community. Relative weight was increased in the control community when compared to the treatment towns, perhaps as a result of the aging of the cohorts. Similar patterns were observed for plasma cholesterol changes. The 2-yr changes were maintained or increased during the 3rd, maintenance yr. The changes in individual values for plasma cholesterol showed low level correlations with dietary cholesterol and saturated fat, but the association with weight change was more important. These results suggest that mass media health education can achieve lasting changes in diet, obesity, and plasma cholesterol on a community level.

Adult↗