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Biomedical subjects

A E Doyle

Publications and source records attributed to A E Doyle.

At least 91 records · Page 5Linked to original sources
PubMed1982

A double-blind comparison of verapamil and labetalol in hypertensive patients with coexisting chronic obstructive airways disease.

A randomized, double-blind, cross-over trial was carried out in nine hypertensive patients with coexisting chronic obstructive lung disease to evaluate the hypotensive efficacy and safety of verapamil and labetalol. The effects on respiratory function were also assessed. Verapamil in doses of 160 mg twice daily was equally effective as 200 mg twice daily of labetalol. Labetalol significantly reduced both forced expiration volume at 1 s (FEV1) and forced vital capacity (FVC), suggesting a bronchoconstrictor effect. Verapamil was devoid of any such effect. Neither drug caused significant side effects.

Aged↗
PubMed1982

Hypertension and calcium antagonists.

1. Recent evidence suggests that mild hypertensives benefit from antihypertensive drug treatment. 2. The variable course of mild hypertension suggests that drug treatment is best reserved for patients whose blood pressures do not fall in repeated observation. 3. The possibility that thiazide diuretics and beta-adrenoceptor blocking drugs may have adverse effects suggest that calcium channel blockers should be considered for the early treatment of mild hypertension.

Airway Resistance↗
PubMed1981

Vasodepressor effects of arachidonic acid and prostacyclin (PGI2) in hypertensive rats.

1. Vasodepressor responses to prostacyclin and nitroprusside were compared in anaesthetized, spontaneously hypertensive rats of the Okamoto strain and Wistar--Kyoto controls, and also in one-kidney, one-clip hypertensive rats and unilaterally nephrectomized controls of the Sprague--Dawley strain. The responses, measured as a percentage of resting blood pressure, did not differ significantly between the hypertensive rats and the normotensive controls within each strain. 2. The effects of intravenous injections of arachidonic acid were also studied in each strain. 3. The vasodepressor effects of high doses of arachidonic acid (1 or 3 mg/kg) were much greater and more prolonged in both groups of hypertensive rats. These differences were abolished by indomethacin (2 mg/kg). 4. Comparisons between the strains showed that whereas Okamoto rats have significantly greater depressor responsiveness to nitroprusside and prostacyclin than Sprague--Dawley rats, the depressor effects of high doses of arachidonic acid (1 and 3 mg/kg) were smaller in the normotensive Wistar--Kyoto than in the Sprague--Dawley rats. 5. It is concluded that hypertensive rats have enhanced ability to transform exogenous arachidonic acid into vasodilator prostanoids. This occurs both in spontaneous hypertension and in experimental renal hypertension. However, rats of the Okamoto strain appear to have reduced ability to form prostacyclin when compared with Sprague--Dawley rats.

Animals↗
PubMed1980

Hypotensive effects of captopril, saralasin and bromocriptine in spontaneously hypertensive rats.

1. Neurosecretion of peptides from superfused neurohypophyses in vitro was inhibited by dopamine. 2. This inhibition was dose-dependent. 3. Intravenous injection of the dopamine agonist, bromocriptine, lowered blood pressure in spontaneously hypertensive rats within 15 min. 4. Saralasin or captopril also lowered blood pressure of spontaneously hypertensive rats, but progressively over a period of 3 h. 5. The results suggest that dopamine and angiotensin have opposite effects on the neurosecretion of vasopressin. 6. Vasopressin appears to be involved in maintenance of blood pressure in the spontaneously hypertensive rat but is apparently not the only factor.

Angiotensin II↗
PubMed1980

A clinical evaluation of serum angiotensin converting enzyme in sarcoidosis.

Angiotensin converting enzyme was measured in the serum of 52 patients with sarcoidosis, 67 healthy control subjects and 64 patients with pulmonary and non-pulmonary diseases. The patients with sarcoidosis were classified on clinical grounds as having active or inactive disease. In 26 patients with active sarcoidosis not taking corticosteroids the mean serum ACE was significantly higher than in normal controls (P less than 0 . 001). 73% of these patients had elevated serum ACE. Only two out of 12 (17%) patients with inactive sarcoidosis not taking corticosteroids had elevated serum ACE. Serum ACE was normal in patients taking oral corticosteroids for longer than two weeks. Eighty per cent of patients with active sarcoidosis with radiological evidence of pulmonary parenchymal involvement had an elevated serum ACE compared to 25% in patients with normal chest X-rays and 60% of those with bilateral hilar lymphadenopathy. All sarcoid patients with hypercalcaemia had elevated serum ACE whereas only half of those with normal serum calcium had elevated ACE. In the patients with other thoracic and granulomatous conditions serum ACE was normal or rarely marginally elevated. Serum ACE appears to be of value in the diagnosis of active sarcoidosis.

Adolescent↗
PubMed1979

Comparison of metoprolol and pindolol in the treatment of mild to moderate hypertension: a double-blind crossover study.

Matched doses of metoprolol and pindolol were administered to 31 hypertensive outpatients in a double-blind randomized crossover trial, which was designed to compare the antihypertensive efficacy and pattern of side effects of the two drugs. Twenty-nine patients completed the study. A tenfold difference in dose (25 +/- 2 mg/day of pindolol and 234 +/- 22 mg/day of metoprolol) was required to produce a similar antihypertensive effect. There was a significantly greater fall in pulse rate during metoprolol treatment. Complaints of dry mouth, mild Raynaud's phenomenon, and eye discomfort were more frequent during treatment with metoprolol; and sleep disturbances and abnormal dreaming patterns were more frequent during treatment with pindolol.

Adult↗
PubMed1978

The combined use of L-alpha-methyldopa hydrazine and methyldopa in the treatment of hypertension.

1. The combined use of alpha-methyldopa and L-alpha-methyldopa hydrazine (a peripheral decarboxylase inhibitor) has been studied, in a double-blind cross-over comparison, with alpha-methyldopa and L-alpha-methyldopa hydrazine placebo in the treatment of eight patients with essential hypertension. 2. L-alpha-methyldopa hydrazine did not enhance the antihypertensive effect of alpha-methyldopa. This suggests that because methyldopa can inhibit its own decarboxylation, peripheral decarboxylation is not an important metabolic pathway for methyldopa and elevated brain levels of methyldopa do not necessarily result in elevated brain levels of methyldopamine.

Adult↗
PubMed1976

Urinary sodium, potassium and creatinine excretion in hypertensive and normotensive Australians.

Studies were made in urine obtained from people attending for routine measurement of blood pressure in a screening programme. Subjects with diastolic blood pressure between 95 and 109 mm Hg excreted significantly more sodium than the group with diastolic blood pressure below 90 mm Hg. Urine volumes, potassium excretion and creatinine excretion did not differ significantly between the groups.

Adult↗
PubMed1976

Double-blind cross-over evaluation of mazindol in the treatment of obese hypertensive patients.

The effect of mazindol (AN 448) on weight and blood pressure was evaluated in a double-blind cross-over trial in 28 obese hypertensive patients, whose blood pressure was under stable control with one or more of the common antihypertensive agents--diuretics, beta-blocking drugs and methyldopa. There was a statistically significant decrease in weight, but no significant change in blood pressure (systolic and diastolic) or pulse rate during active treatment. It was considered that the drug might be of benefit to some patients, provided that they were properly motivated to adhere to the dietary regime.

Adult↗
PubMed1976

Exchangeable sodium in experimental hypertension in rats.

1. Total exchangeable sodium was measured in rats by a radio-sodium equilibration method, before and after the production of hypertension by clipping the left renal artery, with or without contralateral naphrectomy. 2. Clipping of one renal artery with removal of the other kidney produced severe hypertension with no significant changes in exchangeable sodium or plasma renin levels. 3. Clipping of one renal artery without contralateral nephrectomy produced severe hypertension in some animals, but little change in blood pressure in others. The animals which developed severe hypertension had a marked increase in exchangeable sodium with a concomitant rise in plasma renin; the animals with smaller rises in blood pressure did not have these changes. 4. The fact that both plasma renin levels and exchangeable sodium levels increase according to this method, suggests that hypertension in the two-kidney model is renin-dependent.

Animals↗