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Biomedical subjects

A M Barrett

Publications and source records attributed to A M Barrett.

At least 55 records · Page 3Linked to original sources
PubMed1978

Accuracy of an automated blood-gas analyser operated by untrained staff.

Performance of the IL 613 automatic blood-gas analyser has been assessed using a group of 100 "analysts" with no previous training or experience in the use of the instrument. Test material consisted of blood equilibrated to a known PO2 and PCO2 in a tonometer: pH estimations were carried out on thawed aliquots of a large batch of frozen serum which were then equilibrated to a known PCO2. Eighty-six per cent of analyses were within acceptable limits of error. The largest proportion of errors was in the measurement of pH. Satisfactory results were obtained in 98% of the analyses of PO2 and PCO2. Eighty-eight per cent of operators were able to use the analyser after instruction lasting less than 1 min. These results were significantly better than those obtained in a regional survey of 16 blood-gas laboratories, staffed by trained technicians.

Autoanalysis↗
PubMed1975

Inhibition of drug-induced anorexia in rats by methysergide.

Iproniazid was found to reduce food consumption in fasting rats. Combined treatment of iproniazid with tryptophan resulted in a significantly greater anorexic action whilst tryptophan alone had no effect on food consumption. Iproniazid treatment was associated with a significant increase in brain 5-hydroxytryptamine (5-HT) concentration but in association with tryptophan higher brain 5-HT concentrations were recorded. The anorexic action of the iproniazid-tryptophan combination was antagonized in a dose-dependent fashion by methysergide. Equivalent levels of anorexia induced by fenfluramine and mazindol were similarly antagonized by methysergide in a dose-related manner. The results suggest a common role of 5-HT in the inhibition of eating behaviour in fasting rats when anorexia is induced by iproniazid, fenfluramine or mazindol, sensitive to a specific 5-HT antagonist.

Animals↗
PubMed1970

Comparative chronotropic activity of beta-adrenoceptive antagonists.

1. Chronotropic dose-response curves (non-cumulative) for beta-adrenoceptive antagonists were constructed from results in rats anaesthetized with pentobarbitone and depleted of catecholamines by pre-treatment with syrosingopine.2. Depletion of catecholamines lowered resting heart rate and reduced the threshold to the chronotropic action of isoprenaline by about 50%. Eight beta-adrenoceptive antagonists produced a dose-dependent chronotropic response but the maximum response was in all cases smaller than that obtained with isoprenaline. The order of activity was dichloroisoprenaline>LB 46>practolol>INPEA>oxprenolol>pronethalol>alprenolol>I.C.I. 45,763 (Kö 592). Propranolol and sotalol were without significant activity. The duration of the chronotropic response to the antagonists was more prolonged than that to isoprenaline. Propranolol caused a parallel shift to the right of the dose-response curves for the agonist effects of the antagonists.3. Estimation of beta-adrenoceptor blocking activity in anaesthetized cats gave an order of activity dissimilar to that found for maximum agonist responses: LB 46 > oxprenolol > alprenolol > propranolol > I.C.I. 45,763 > practolol > dichloroisoprenaline > sotalol > INPEA > pronethalol.4. Consideration of chemical structure and physico-chemical properties did not explain the differences between the agonist activities of the adrenoceptive antagonists.

Acetanilides↗