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Biomedical subjects

H L Taylor

Publications and source records attributed to H L Taylor.

At least 37 records · Page 2Linked to original sources

Improvement in hypertension detection and control from 1973-1974 to 1980-1981. The Minnesota Heart Survey experience.

Blood pressures from a 1980-1981 survey of 1,656 adults in Minneapolis-St Paul were compared with BPs from a similar community survey of 3,475 adults conducted in 1973-1974. Mean age-adjusted BPs in 1980-1981 were 3 mm Hg lower for men and 2 mm Hg lower for women than in 1973-1974. Hypertension prevalence, defined as diastolic BP of 95 mm Hg or greater and/or use of antihypertensive medication, was essentially unchanged. In 1973-1974, however, only 40.4% of hypertensive persons had adequately controlled BPs, 13.7% were treated but had conditions that were uncontrolled, 20.4% had known hypertension but were untreated, and 25.5% had previously undetected hypertension. In 1980-1981, the respective percentages were 76.1%, 8.5%, 8.8% and 6.6%. These impressive changes in hypertension detection and control may have contributed to the recent decline in cardiovascular disease mortality in this community.

Adult↗

The relationship of body fat weight, determined densitometrically, to relative weight and triceps skinfold in American youths, 12-17 years of age.

The relationship between fat weight, measured densitometrically, and the triceps skinfold and Quetelet's Index has been analyzed by means of linear regression analysis of 235 American youths, 12-17 years of age; 48 males and 41 females were from Minneapolis and 121 males and 25 females from the Greater Philadelphia area. Validation was accomplished by using the results of 10 separate regression analysis, each on 90% of the sample, the remaining 10% serving in each instance as the validation group; this is known as the Jackknife Method. When the Minneapolis and Philadelphia components were pooled, suitable regression models were derived with standard deviations of the errors of prediction of 3.330 kg in males and 2.056 in females. When the sample was subdivided by city the SD's remained essentially the same, but the mean errors were larger. It is concluded that the linear regression models can be used on closely similar populations to estimate fat weight for groups, but estimates for individuals may be expected to have an error of +/- 5-6 kg (i.e., 2 SD's) and are therefore not likely to be suitably accurate for use. The regression weights indicate a greater contribution of the triceps skinfold to fat weight than of Quetelet's Index in males. In females the reverse was found. This may affect sex differences in prevalence rates of obesity, if the diagnosis is based upon a single anthropometric indicator.

Adipose Tissue↗

Blood lipids in young men followed 32 years.

The relationship of baseline characteristics to serum cholesterol at baseline (CHL47) when aged 16-25 (mean 20.5) yr and at 32-yr follow-up (CHL79) was assessed in 162 men. Mean CHL rose over the follow-up period. CHL47 predicted CHL79 (r = 0.61, p less than 0.001) but not CHL79-CHL47. The mean (+/- SD) weight change (DW) was 12.0 kg (+/- 26.0 kg). DW was not significantly related to CHL47, but was independently related to CHL79-CHL47 (4 = 0.30, p less than 0.001). Age, height, DW, any of 7 measures of baseline obesity and CHL47 predicted CHL79 with R2 of 0.40 and CHL79-CHL47 with R2 of 0.37. Thus, weight change but not baseline relative weight was a determinant of serum cholesterol change from youth to middle age. There was strong tracking of serum cholesterol over this period.

Adult↗

Indices of obesity and blood pressure in young men followed 32 years.

In order to assess the effects of baseline indices of obesity, lean body mass, blood pressure, and weight change on future blood pressure, 112 former college men were examined 20 and 32 years after initial examination at age 20.5 (+/- 2) yr. Baseline body weight, relative body weight, body mass index and body density all showed similar significant correlations with baseline systolic blood pressure (r = 0.35, 0.31, 0.30 - 0.31) but not baseline diastolic blood pressure (r = 0.13, 0.07, 0.10 - 0.11) or follow-up blood pressure. Changes in body weight, relative body weight, body mass index and sum of skinfolds were significantly correlated with change in both systolic and diastolic blood pressure. Baseline systolic blood pressure was the most powerful predictor of 20- and 32-yr follow-up systolic (r = 0.57, 0.42), but baseline diastolic was a much weaker correlate of follow-up diastolic blood pressure (r = 0.24, 0.18).

Adolescent↗

Relationship of physical characteristics and life habits to treadmill exercise capacity.

Apparently healthy middle-aged men (n = 175) were recruited from a population sample and completed questionnaires about habitual physical activity, smoking, beverage consumption and sleep habits. Body mass index (BMI), heart rate and blood pressure were measured at rest and during submaximal exercise; frequency of ventricular premature beats (VPB) on an ECG rhythm strip; hand grip strength; and serum cholesterol. These characteristics were correlated with duration of treadmill exercise by the Bruce protocol. Univariate analysis indicated that treadmill performance was significantly and positively correlated with leisure-time physical activity and personal reports of sweating and/or dyspnea occurring regularly during such physical activity. Performance was negatively correlated with age, BMI, resting heart rate, cigarette smoking, and consumption of caffeine-containing beverages, but was insignificantly related to job physical activity, hand grip strength, alcohol consumption, sleep habits, blood pressure, cigar smoking, serum cholesterol, and the frequency of VPB. A 0.75 multiple correlation coefficient was found between treadmill performance and 11 of the above variables and the r is increased to 0.81 by adding heart rate during submaximal exercise. It is concluded that substantial prediction of work capacity and physical fitness of population is achieved by questionnaires and easily obtained, noninvasive physical measures.

Adult↗

Effect of pentobarbital anesthesia on vulnerability to ventricular fibrillation.

Ventricular fibrillation threshold (VFT), frequently determined in dogs during pentobarbital sodium anesthesia, usually is replaced by a single repetitive extrasystole threshold (SRET) or a multiple repetitive extrasystole threshold (MRET) determination in conscious animals and in the human being. In the present study SRET, MRET, and VFT were determined initially in 39 pentobarbital sodium-anesthetized dogs. One week later these three thresholds were redetermined during anesthesia in 13 of the 39 dogs (control group). In the remaining 26 dogs (experimental group), thresholds were redetermined while the dogs were conscious. Significant changes in threshold values occurred only in the experimental group for VFT (P < 0.001) and MRET (P < 0.02). The square of the linear correlation coefficient showed conscious state MRET to be a good predictor of conscious state VFT (R2 = 0.90). Conscious state SRET and anesthetized state VFT showed less predictiveness for the conscious VFT (R2 = 0.72 and 0.51, respectively). These data indicate that MRET may be preferable to SRET as an index of VFT. The SRET, MRET, and VFT determined during pentobarbital anesthesia may not accurately reflect the value of these parameters in the conscious animal.

Animals↗

Strenuous physical activity, treadmill exercise test performance and plasma high-density lipoprotein cholesterol. The Lipid Research Clinics Program Prevalence Study.

During the Lipid Research Clinics North American Prevalence Study, plasma lipoprotien determinations and treadmill exercise testing were performed on 2319 white men and 2067 white women ages 20 years or older randomly selected from population surveys by nine clinics in the U.S. and Canada. Before exercise testing, participants were asked if they performed any strenuous physical activity on a regular basis. Data were analyzed to determine the relationship of plasma high-density lipoprotein (HDL) cholesterol to treadmill exercise test performance and a self-report of strenuous activity. Neither treadmill exercise test duration nor heart rate response to submaximal exercise was significantly related to HDL cholesterol levels for either men or women. However, participants who reported some strenuous physical activity generally had higher HDL cholesterol levels than those who reported none, and the more active men ages 30-49 years and active women ages 20-39 had significantly higher values (p < 0.05). When HDL cholesterol was adjusted for age, body mass index, alcohol use, cigarette smoking and interclinic population variation, more active men (47.1 vs 45.2 mg/dl; p = 0.0001) and more active women (59.6 vs 57.7 mg/dl; p = 0.02) had higher HDL cholesterol levels than their sedentary counterparts. Thus, the association between HDL cholesterol and reported physical activity was, at least in part, independent of other factors that influence HDL cholesterol concentration, but was not associated with exercise tolerance as determined by treadmill exercise testing.

Adult↗

Plasma high-density lipoprotein cholesterol: association with measurements of body mass. The Lipid Research Clinics Program Prevalence Study.

Relationships between weight, height and ponderal indexes and plasma high-density lipoprotein (HDL) cholesterol and triglyceride were assessed by the Lipid Research Clinics Prevalence Study for 6865 white children and adults (3517 males and 3348 females). Overall, weight, weight/height, weight/height and weight/height were significantly and inversely associated with plasma HDL cholesterol levels and positively associated with plasma triglyceride levels. When the relationships of Quetelet index (weight/height) to HDL cholesterol were assessed by multiple regression analysis, including the explanatory variables of cigarette smoking, alcohol intake and exogenous estrogen hormone use, the Quetelet index was significantly and inversely associated with HDL cholesterol levels in children (by age 12-16 years) and adults of both sexes. After covariance adjustment for smoking, alcohol intake, hormone use and age, mean HDL cholesterol levels for individuals at the Quetelet tenth percentile were 3 mg/dl higher than for those at the fiftieth percentile, and these in turn were 3-4 mg/dl higher than for those at the ninetieth percentile. These differences in HDL cholesterol differences reported to be related to coronary heart disease mortality. Improved approaches to the primary prevention of atherosclerosis may be realized by a better understanding of the inverse relationship of body mass to HDL cholesterol levels.

Adolescent↗

Effect of submaximal exercise on vulnerability to fibrillation in the canine ventricle.

The risk of instantaneous death due to ventricular fibrillation was compared in resting and exercised dogs. Three weeks before testing, all dogs had bipolar left ventricular stimulating electrodes implanted and a reversible snare was placed around the anterior descending coronary artery. The dogs were randomly assigned to either an exercise (13 dogs) or a control (12 dogs) group. We measured ventricular fibrillation thresholds (VFTs) in all dogs before and after inducing ischemia by tightening the snare while the dogs stood at rest. The next day, nonischemic and ischemic VFTs were redetermined for control dogs at rest and for the exercise group during a treadmill run. No statistically significant changes were noted within and between groups in nonischemic or in ischemic VFTs at rest. In five exercise dogs, spontaneous ventricular fibrillation occurred during the first 8 minutes of the ischemic run, For the eight other exercise dogs, running increased the mean drop in VFTs during coronary occlusion by 23% (p less than 0.01). These data suggest that moderate dynamic exercise may greatly enhance the risk of ventricular fibrillation and sudden death in the presence of myocardial ischemia. In the absence of ischemia, exercise does not appear to increase vulnerability to ventricular fibrillation.

Animals↗

A method for assessing volunteer bias and its application to a cardiovascular disease prevention progamme involving physical activity.

Studies of chronic disease may require long-term observation of volunteer participants. This is a characteristic of investigations of primary or secondary prevention of cardiovascular disease by increased level of physical activity. Activation of sedentary, middle-aged, high risk men requires a substantial personal commitment on their part to a long-term programme. Because of self-selection, individuals who volunteer for such programmes cannot be assumed to be representative of the populations from which they come. To the best of our knowledge, there has been no systematic investigation of such self-selection based upon a study designed for that purpose. We found little consistent tendency for vouunteering behaviour to be associated with serum cholesterol, blood pressure, relative weight, level of activity at work, or Type A hehaviour variables.

Adult↗