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Biomedical subjects

J R Turner

Publications and source records attributed to J R Turner.

At least 109 records · Page 6Linked to original sources
PubMed1988

Equivalence of continuous flow nebulizer and metered-dose inhaler with reservoir bag for treatment of acute airflow obstruction.

Traditionally, patients with acute airflow obstruction are treated with bronchodilator aerosols delivered by continuous flow nebulizers. While bronchodilator administration with the metered dose inhaler (MDI) and reservoir or spacer attachment is as effective as administration with the nebulizer in most settings, the former has not been widely accepted for treatment of acute airway obstruction in the emergency room. We compared the efficacy of the continuous flow nebulizer to that of the MDI with InspirEase (reservoir spacer) in 75 patients (45 men and 30 women), ages 18-73 (chi 44 years) who presented to the emergency room with acute asthma and COPD. Subjects in each group (22 COPD and 53 asthma) were randomly assigned to treatment with three puffs of metaproterenol (0.65 mg/puff) via the MDI with InspirEase plus nebulizer with placebo, or placebo MDI with InspirEase plus nebulizer with 15 mg metaproterenol in double blind fashion. Either treatment was given three times at 30 min intervals. The FEV1 and dyspnea scores according to the Borg scale were measured at baseline, 30 min after the first treatment, and 30 min after the third. There was no significant outcome difference between the two treatments in either diagnostic group. There also was no significant outcome difference for patients with baseline FEV1 less than 0.9L. Serum theophylline levels, the need for concomitant therapy with corticosteroids, or additional emergency room therapy after the study, hospitalizations and treatment side effects did not differ between treatment groups. We conclude that there is no demonstrable advantage of a continuous flow nebulizer over an MDI with InspirEase for the treatment of acute airflow obstruction.

Adult↗
PubMed1987

Heart rate reactions to standard laboratory challenges and a naturalistic stressor.

Extreme high and low heart rate reactors were selected on the basis of responses to two laboratory stressors; a video game, and mental arithmetic. The heart rates of the same subjects were then recorded during a public speaking competition. Heart rate reactions to this more naturalistic stressor were generally in line with the laboratory-based designations.

Adult↗
PubMed1987

A comparative evaluation of heart rate reactivity during MATH and a standard mental arithmetic task.

Heart rate was monitored while 20 young males completed MATH, a computer-operated mental arithmetic task specifically designed for use in experiments involving subjects of heterogeneous numerical ability, and a standard mental arithmetic task used in this laboratory on several occasions. Both tasks elicited sizeable increases in heart rate, and comparison of subjects' reactivity scores revealed significant inter-task consistency of reaction.

Adult↗
PubMed1987

A family study of developmental effects upon blood pressure variation.

In an earlier study of blood pressure variation in middle aged parents and their young adult twin offspring, the greater blood pressure variation observed in the parent sample was accounted for in terms of an increasing influence of individual environmental experiences with increasing age and a commensurate reduction in the impact of heredity. In the present study, the sample size was enlarged to provide a more powerful test of these effects. Maximum likelihood model-fitting techniques were applied to blood pressure covariation in balanced pedigrees, consisting of 85 families (40 MZ and 45 DZ twin pairs). As before, our analysis indicated that a developmental effect was a salient factor in the older age group.

Adult↗
PubMed1986

Purification and characterization of a membrane protein (gp45-70) that is a cofactor for cleavage of C3b and C4b.

Based on preliminary evidence indicating that a cell-associated protein of U937 (a human monocyte-like cell line) possessed cofactor activity and was not the C3b/C4b receptor, we sought to further characterize this protein. A sequential four-column purification procedure was devised that includes C3(H2O) affinity chromatography to isolate in reasonable yields and purity a cell-associated protein of U937 and several other human cell lines. Based on its pattern and Mr on SDS-PAGE, acidic pI, and ligand specificity, it is identical to a recently described C3(H2O) or C3b-binding membrane glycoprotein of human PBL and cell lines; having no presently identified function, it was termed gp45-70. After purifying this protein, we determined its functional capabilities and compared them to those of the other complement proteins with regulatory activity directed at components comprising the C3 convertases. This protein was the most efficient (50 times that of H) yet-described cofactor for the I-mediated first cleavage of C3b. It also was a cofactor for the first cleavage of C4b, but was not as efficient as C4bp. The second cleavage of C3b and C4b was not efficiently mediated. It had no ability to accelerate decay in the classical or alternative pathway C3 convertases. Based on this unique activity profile and ability to be surface labeled, we have renamed this molecule membrane cofactor protein (MCP). We suggest that this protein plays a major role in preventing autologous complement activation.

Antigens, CD↗
PubMed1986

Temporal and inter-task consistency of heart rate reactivity during active psychological challenge: a twin study.

Heart rate was monitored while 22 pairs of young male monozygotic and 29 pairs of young male dizygotic twins were exposed to a video game and a mental arithmetic task. The heart rate reactions of the monozygotic twins showed much greater concordance than those of the dizygotic twins. Analysis of the data for the 102 individuals demonstrated reliable inter-task consistency of heart rate reaction. In addition, comparison of the heart rate reactions of ten pairs of monozygotic and ten pairs of dizygotic twins who had been tested more than a year earlier and their present reactivities revealed impressive temporal consistency.

Adolescent↗
PubMed1986

The effects of level of difficulty of mental arithmetic challenge on heart rate and oxygen consumption.

Heart rate plus various metabolic and ventilatory indices were monitored while 18 young males engaged in a mental arithmetic task, structured to include 3 levels of difficulty; easy, difficult and impossible. Measurements were also taken while subjects undertook graded isotonic exercise on a bicycle ergometer; for each subject heart rate was plotted against oxygen consumption over the various exercise loads. Knowing oxygen consumption during the psychological tasks, these regression equations permitted the calculation of expected heart rates during each task condition and thus the computation of 'additional heart rate' as the difference between actual and predicted heart rate values. Additional heart rate was sensitive to variations in difficulty level; the difficult condition elicited reliably more additional heart rate than the easy and impossible conditions. Subjects' performance as well as their perceptions closely reflected the a priori classification of difficulty. Although subjects rated the easy condition as particularly unengaging, the impossible condition attracted relatively high rates of task involvement. It was argued that self-reports of this sort are probably more susceptible than cardiac activity to social demand characteristics.

Adolescent↗
PubMed1986

Graded mental arithmetic as an active psychological challenge.

A computer-operated mental arithmetic task is outlined which presents questions at a level of difficulty continuously determined by subjects' accuracy of response on the previous question. The programme incorporates 5 levels of difficulty, and all questions concern the addition or subtraction of two numbers which vary in digit-span according to the current level of difficulty. Response requirements are manual rather than verbal so that, in addition to monitoring heart rate, subjects' exhaled air may be collected throughout the task in order to determine oxygen consumption.

Computers↗
PubMed1986

Familial and individual influences on blood pressure.

Although familial aggregation of blood pressure is well documented, few studies have considered the changing contribution of genetic and environmental influences during adulthood. Applying maximum likelihood model fitting to blood pressure covariation in balanced pedigrees including both parents and their young adult twin offsprings (25 MZ, 32 DZ, aged between 16 and 24 years), it is shown that the increased variation in parents is explained by such developmental changes. For DBP, an apparent reduction in heritability from 68% to 38% from young adulthood to middle age results from the increasing impact of individual environmental experience (E1), with little or no influence from shared family environmental (E2). For SBP, shared environmental effects may play a part. Given the relatively small size of the present sample, the conclusions are to be seen as tentative. An augmented family study, incorporating middle aged twins and their young adult offspring, will clarify the causation of these developmental changes.

Adolescent↗
PubMed1986

Preparation and evaluation of 3,4''-ester derivatives of 16-membered macrolide antibiotics related to tylosin.

A large group of ester derivatives of tylosin-related macrolides was prepared in which the hydroxyl groups at C-3 and C-4'' were acylated by either chemical or biochemical methods. Most of the derivatives exhibited excellent in vitro antimicrobial activity. However, only the 3,4''-diacyl derivatives of tylosin and macrocin showed any significant improvements of in vivo efficacy against experimental infections in rodents.

Acylation↗
PubMed1985

A twin study of cardiac reactivity and its relationship to parental blood pressure.

The cardiac reactivity of 40 monozygotic and 40 dizygotic pairs of young male twins was monitored during psychological challenge, as afforded by a video game. The observed pattern of variation could not be accounted for solely by environmental factors. In fact, a simple genetic model that implicated additive genetic effects, along with those stemming from individual environments, best fitted the data. In addition, cardiac reactions were substantially greater for subjects whose parents both had relatively elevated blood pressure. Overall, these data suggest individual differences in cardiac reactivity have a heritable component, and that high reactivity may be a precursor of elevated blood pressure.

Adolescent↗