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Biomedical subjects

W A Littler

Publications and source records attributed to W A Littler.

At least 19 recordsLinked to original sources
PubMed1979

Cold-pressor test.

Explore the source record for details and available documents.

Cardiomyopathies↗
PubMed1979

Influence of once-daily administration of beta-adrenoceptor antagonists on arterial pressure and its variability.

Intra-arterial pressure was recorded over 24 h in hypertensive patients before and during long-term treatment with beta-adrenoceptor antagonists given once daily under standardised conditions. Arterial pressure was reduced throughout the 24 h after the last dose as was variability of pressure during physical activity; variability during sleep and rest did not change significantly.

Acebutolol↗
PubMed1979

Sleep and blood pressure: further observations.

Twenty-seven healthy people with a wide range of casual blood pressure readings (120/70 to 230/120 mm. Hg) had their blood pressure recorded continuously over a 24-hour period. Arterial pressure fell during sleep and only rose appreciably after the patients had awakened and a further rise was associated with physical activity, once they were out of bed. This pattern was observed in 18 untreated patients and in nine currently receiving hypotensive treatment. This study suggests that arterial pressure is not specifically related to time and is chiefly governed by physical activity and sleep.

Adult↗
PubMed1979

Effects of beta-adrenoreceptor antagonists on sino-aortic baroreflex sensitivity and blood pressure in hypertensive man.

1. Sensitivity of the sino-aortic baroreflex was investigated before and after acute (23 patients) and chronic (23 patients) beta-adrenoreceptor antagonism in patients with essential hypertension. 2. Sensitivity was inversely related to age (r = -0.60) and systolic blood pressure (r = -0.46); a positive relationship was noted between sensitivity and initial pulse intervals (r = 0.40). 3. Sensitivity increased significantly in patients less than 40 years of age after chronic treatment. No change occurred after acute treatment or in older patients treated chronically. 4. The fall in ambulatory intra-arterial blood pressure after chronic treatment was unrelated to alteration of baroreflex sensitivity.

Acebutolol↗
PubMed1979

Plasma noradrenaline concentrations at different vascular sites during rest and isometric and dynamic exercise.

1. Blood samples were obtained simultaneously from femoral artery and vein, pulmonary artery and antecubital vein at rest and during isometric and dynamic exercise in six patients during cardiac catheterization and plasma noradrenaline was measured radioenzymatically. 2. Analysis of variance indicated that differences between vascular sites were not significant, whereas differences between patients (P less than 0.001) and differences between activities (P less than 0.001) were significant. 3. Mean systemic arterial concentrations tended to be lower than pulmonary arterial concentrations during each activity, although the difference was not significant. 4. We conclude that forearm venous plasma noradrenaline concentrations are representative of those from other sites.

Adult↗
PubMed1979

Factors determining the variability of arterial pressure in hypertension.

1. Intra-arterial pressure was recorded continuously in 26 patients with uncomplicated essential hypertension under standardized conditions. Pressure was analysed beat by beat by computer and variability measured as the standard deviation of the normally distributed frequency histogram. 2. Variability was strongly influenced by physical activity, being least during sleep and increasing progressively with bed rest and ambulation. Variability during daytime was not related to time. 3. Systolic variability correlated directly with systolic pressure. An independent inverse relationship with baroreflex sensitivity was observed. Systolic variability tended to increase with obesity. 4. None of the following were related independently with variability: age; race; sex; plasma renin activity; plasma angiotensin II; plasma noradrenaline; plasma adrenaline.

Adolescent↗
PubMed1979

Onset and duration of beta-adrenergic receptor blockade following single oral dose acebutolol hydrochloride (Sectral).

1. The onset and duration of action of once daily acebutolol (400 mg) on resting and exercise heart rate and blood pressure were studied in normal subjects in a double-blind, cross-over trial against placebo. Subjects were studied 1.5, 3, 8 and 24 h after the first dose and 24 h after the fifth dose. 2. Resting and exercise heart rate and blood pressure were significantly reduced within 90 min of the first dose. 3. A significant reduction in these variables persisted throughout 24 h after the fifth daily dose. However, at 24 h the effects were considerably attenuated, the falls in resting and exercise systolic blood pressure being only 5%. 4. A linear relationship was noted between log serum drug level and percentage reduction of exercise heart rate.

Acebutolol↗
PubMed1978

Critical assessment of diagnostic value of endomyocardial biopsy. Assessment of cardiac biopsy.

Right or left ventricular endomyocardial biopsy with the Konno or the Olympus bioptome was attempted in 73 patients aged 5 months to 61 years, with 82 per cent success. Light and electron microscopy showed non-specific features in over half the biopsies with new or diagnostically useful information in only 10 per cent of cases, usually as a result of electron microscopy. The method is safe but is of strictly limited diagnostic value and is likely to be of most help as a research tool in the biochemical study of cardiomyopathies.

Adolescent↗
PubMed1978

Closing volume during normal pregnancy.

Serial lung function studies were performed in ten healthy, primiparous women aged 21--28. Measurements were made at two-monthly intervals during pregnancy and included functional residual capacity (FRC), total lung capacity (TLC), vital capacity (VC), specific conductance (SGaw) and closing volume (CV) on each occasion. Closing volume expressed as formular: (see text), showed a progressive rise during pregnancy in all subjects with a linear relationship to time (P less than 0.001, P greater than 0.01, respectively). No consistent changes in lung volume could be shown during pregnancy over the study period. It is suggested that the increase in closing volume during pregnancy might result in abnormalities of distribution of ventilation sufficient to explain the maternal blood gas disturbances of pregnancy.

Adult↗
PubMed1977

Cardiac biopsy in childhood.

Endomyocardial biopsy was attempted in 18 children aged 5 months to 15 years with 82% success. Biopsies obtained from 15 children were examined by light and electron microscope making positive morphological diagnoses in 3 cases. The biopsy findings were actively helpful in 7 other cases, which contrasts with experience in adult biopsy series. This is a low risk procedure which does not add to the hazards of cardiac catheterization in children.

Adolescent↗
PubMed1976

Blood pressure variability in patients on beta-blockers.

The direct arterial blood pressure was monitored over 24 hours in unrestricted untreated patients in order to obtain the average pressure and standard deviation over 24 hours. The standard deviation was taken as the index of variability of pressure. In eight subjects the study was repeated three months after commencement of treatment with a beta-adrenergic blocking agent (tolamolol, 300 mg/day). In these subjects tolamolol resulted in a fall in mean blood pressure from 107 to 92 mmHg (P less than 0-05) and a fall in heart rate from 82 to 70 beats per minute (P less than 0-01). The variability in blood pressure, however, was unaffected by treatment.

Adrenergic beta-Antagonists↗