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Biomedical subjects

H Blackburn

Publications and source records attributed to H Blackburn.

At least 145 records · Page 8Linked to original sources
PubMed1981

Effects of thiazide diuretics on plasma lipids and lipoproteins in mildly hypertensive patients: a double-blind controlled trial.

A blood lipid-lipoprotein elevating effect of the diuretics hydrochlorothiazide and chlorthalidone in mildly hypertensive men has been established by a cross-over, randomized controlled trial, confirming previous clinical observations. Compared to baseline, plasma total cholesterol increased 6% and 8% and triglycerides 17% and 15% under treatment with hydrochlorothiazide and chlorthalidone, respectively. A cholesterol-lowering diet largely prevents this increase. Because these effects may be long-lasting and may cancel part of the potential benefit of blood pressure control in mildly hypertensive patients, with thiazide diuretics attention should be given to prescription of a cholesterol-lowering diet and to periodic monitoring of blood lipid levels. Different antihypertensive agents might be considered in patients with elevated blood lipid levels. Other antihypertensive agents currently in use need to be studied for potential effects on lipid metabolism.

Adult↗
PubMed1980

Ventricular premature beats: screening and induction tests in normal men.

Effective future research on the significance of ventricular premature beats (VPB) and their therapeutic suppression require improved and simpler methods for arrhythmia detection, characterization, and measurement. This study considers the comparative yield, repeatability, and validity of several methods of VPB detection and induction in a sample of the general population of middle-aged men. Isometric exercise inducers VPB. Treadmill exercise both induces and suppresses VPB. Cartotid sinus pressure and cold stress provide a small extra yield of VPB.

Adult↗
PubMed1980

Does sex make a difference? Gender, age, and stimulus realism in perception and evaluation of aggression.

Judged aggressiveness and its justifiability were examined with caricature cartoons and films of people doing comparable things. Effects of viewer gender, interactant gender, and facial expression were examined. Facial expression strongly affected both types of judgment, viewer gender had no influence, and interactant gender contributed slightly. Real-cartoon differences were significant, but accounted for little variance. Major response patterns were similar for films of people and cartoons. In two developmental studies, only facial expression influenced judgments of friendliness-hostility in cartoons, but condemnation of aggression decreased as viewer age increased. Results with films of real children followed those for cartoons. Facial expression influenced judged aggressiveness, but only viewer age affected judged justifiability. Cross-experiment comparisons revealed that facial expression and the facial expression X real-cartoon interaction yielded major differences on both dependent variables. Subject and interactant gender were not significant for major dependent variables. Results of the developmental studies were similar to adults' suggesting that for judgments of simple aggressive acts, sex makes no difference, but facial expression does make a difference.

Adolescent↗
PubMed1979

Diet and serum cholesterol: do zero correlations negate the relationship?

The confounding that results from the uncontrolled conditions under which most epidemiologic observations are made is sufficient to undermine their validity with respect to investigation of the relationship between diet and serum cholesterol. In this paper, the authors show, using both a mathematical model and referring to empirical data, that if certain variances are sufficiently great, even when there is cause and effect, correlation coefficients close to zero would be expected from the actual data of a cross-sectional study. Cross-sectional designs are therefore not suitable for studying this relationship.

Cholesterol↗
PubMed1979

Ventricular premature contractions: a randomized non-drug intervention trial in normal men.

The influence of a 6-week intervention on factors thought to be related to ectopic cardiac rhythms was tested in normal men with frequent ventricular premature contractions (VPCs), using a randomized, controlled and partial crossover design. The VPC intervention trial experimental regimen included total abstinence from caffeine and smoking, reduction of alcohol intake, and a physical conditioning program. Effects were studied in detail among 81 healthy men with persistent VPCs. VPCs were measured during standard states of rest, dynamic and isometric exercise and other stresses, and 24-hour ambulatory monitoring. Adherence to the treatment was excellent. The experimental group achieved more than 80% of activities asked of them, and little "contamination" occurred in the control group. VPCs were analyzed according to VPC/min, VPC/man and VPC/total number of heart beats. Moderate changes in VPC rates occurred in both experimental and control groups but no significant group differences were found at rest or during any induction test. This 6-week, multiple-factor "hygienic" intervention program had no significant influence on the frequency or occurrence of VPCs in apparently normal men with persistent and frequent VPCs. Because the mechanisms and the significance of VPCs are different in patients with ischemic heart disease, our approach and methods may be useful for similar trials among cardiac patients of adjunct or non-drug therapy for ectopic rhythms.

Adult↗
PubMed1978

Ventricular premature beats. Reliability in various measurement methods at rest and during exercise.

The yield and reproducibility of various methods of ventricular premature beat (VPB) detection are examined in otherwise healthy middle-aged men first found to have VPB in a 2-min lead I ECG rhythm strip. With a combination of an isometric and treadmill exercise test, VPB were repeatedly detected in 83%. Test-retest reliability in classifying the subjects by frequency of VPB was 67%. The reliability of detecting complex VPB was 47% for multiform VPB, 35% for pairs of VPB, 17% for runs and 36% for VPB showing the R-on-T phenomenon. These data suggest that simple and complex VPB detected by the described methods among normal men are poorly reproducible in the individual. Taking the VPB reproducibility for the group as a whole, the proportion of subjects having different frequency or kinds of ectopic beats is reasonably stable for the different test occasions.

Adult↗