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E Leach

Publications and source records attributed to E Leach.

14 recordsLinked to original sources

Effect of personality on magnitude-estimation scaling of complex auditory stimuli.

The purpose of the present study was to examine the effect of the personality trait of extraversion/introversion on magnitude-estimation scaling of complex auditory stimuli. Two groups of subjects, 10 who liked rock music (M age = 22.4 yr.) and 10 who disliked rock music (M age = 21.9 yr.), were tested. Subjects were instructed to assign numerical values to a random series of nine suprathreshold intensity levels of a 10-sec. sample of rock music. Each subject was given the Eysenck Personality Inventory, a test designed to measure the personality trait of extraversion/introversion. Statistical analyses indicated that the personality trait of extraversion/introversion did not appear to have an effect on the way the subjects scaled the rock-music stimulus.

Adolescent

Effect of acetylsalicylic acid on platelet aggregation and thromboxane B2 production in flowing aortic blood in the rat studied with a filter loop technique.

A method of measuring in vivo platelet function using a filter loop technique has been used to study platelet aggregation in response to Adenosine Diphosphate (ADP) and Sodium Arachidonate infusion in flowing aortic blood in the rat. ADP infusion produced reversible platelet aggregation in vivo with no change in thromboxane B2 (TXB2) levels whereas sodium arachidonate infusion resulted in virtually irreversible aggregation with a rise in TXB2 levels. Oral Acetylsalicylic Acid (ASA) in doses of 1-100 mg/kg had no effect on ADP induced aggregation but prevented platelet aggregation in vivo induced by sodium arachidonate and the concomitant rise in TXB2 levels.

Adenosine Diphosphate

The effects of vincristine on platelet aggregation studied by a filter loop technique in the rat.

1 A method for measuring aggregation of platelets of adenosine diphosphate (ADP) is described using a filter inserted into the flowing aortic blood in the rat. 2 Repeated infusions of ADP resulted in a fall in the calculated aggregation index without significant changes in the platelet count. 3 Vincristine (0.05 mg/kg) intravenously caused significant inhibition of ADP-induced platelet aggregation. 4 Infusion of ADP caused some peripheral vasodilatation though it is unlikely that this contributed to the effects seen to any great extent.

Adenosine Diphosphate

Resolution of pulmonary hypertension and other features induced by chronic hypoxia in rats during complete and intermittent normoxia.

Rats subjected to 10% O2 (hypoxic rats) for various periods and recovery regimens were compared with control animals with respect to pulmonary artery pressure (Ppa), right ventricular hypertrophy (RVH), and muscularisation of small pulmonary vessels. Mean Ppa was measured in anaesthetised animals spontaneously breathing air and rose from 16 mmHg in controls to 36 mmHg in rats exposed to hypoxia for three weeks. Ppa had returned to normal after 20 weeks' recovery in air. RVH regressed a little more quickly, but muscularisation of small pulmonary vessels. Mean Ppa was measured in anaesthetised animals spontaneously breathing air and rose from 16 mmHg in controls to 36 mmHg in rats exposed to hypoxia for three weeks. Ppa had returned to normal after 20 weeks' recovery in air. RVH regressed a little more quickly, but muscularisation of small pulmonary vessels was still apparent after 20 weeks. Some hypoxic rats were subjected to an intermittent normoxic recovery regimen for either 40 or 80 hours a week in air, the remainder in 10% O2. Some reduction in RVH probably occurred after six weeks on the 80-hour regimen, but there was no reduction in Ppa or muscularisation of small pulmonary vessels. These results suggest that the pulmonary hypertension of chronic alveolar hypoxia resolves very slowly and is probably related to structural changes in the pulmonary vessels. Their relevance to human cor pulmonale and intermittent long-term oxygen treatment for these patients is discussed.

Altitude

Resolution of hypoxic changes in the heart and pulmonary arterioles of rats during intermittent correction of hypoxia.

1. Rats kept in a hypoxic chamber (10% O2) for 3 or more weeks developed right ventricular hypertrophy, muscularization of pulmonary arterioles and polycythaemia. These changes resemble those found in human hypoxic disease and, in particular, in patients dying from chronic airways obstruction. 2. Resolution of these changes was studied in a normal environment and in an intermittently normal, intermittently hypoxic environment. The latter regimen modelled the situation of patients with cor pulmonale receiving long-term intermittent oxygen therapy. 3. In a normal environment right ventricular hypertrophy and polycythaemia were resolved in 6 weeks but vessel changes were not resolved in 12 weeks. 4. In the intermittently normoxic environment (40 or 80 h in air per week) there was some resolution of right ventricular hypertrophy in 6 weeks but no significant reduction in vessel thickening or in polycythaemia in 12 weeks.

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Child