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Biomedical subjects

P Keane

Publications and source records attributed to P Keane.

42 records · Page 3Linked to original sources
PubMed1980

Genetic studies of daily variations of first-step enzymes of monoamines metabolism in the brain of inbred strains of mice and hybrids. II. Daily variations of tyrosine hydroxylase activity in the locus coeruleus.

Daily variations of tyrosine hydroxylase (TH) activity in the locus coeruleus of 3 inbred strains of mice (BALB/c; C57BL6; C57Br) and the F1 hybrids obtained from BALB/c and C57BL/6 are discussed. Precise characteristics of the circadian rhythms were observed in each strain. They were found significantly different in two genetically pure parents (BALB/c and C57BL6). In their two F1 hybrids the daily variation of TH activity was similar to that observed in one of the parents (C57BL6). This strongly suggests selective and genetically controlled mechanisms of regulation responsible for the daily variation of TH activity in the locus coeruleus of mice.

Animals↗
PubMedDate not supplied

Evidence for a relationship between recovery from anaesthesia, modified state of consciousness and striatal voltammetric levels of ascorbic acid.

The effects of various procedures which modify consciousness were studied on the extracellular concentration of ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindolacetic acid (5HIAA) in rat striatum, as measured by differential pulse voltammetry (DPV) with electrically pretreated carbon fibre micro-electrodes (CFE). Recovery from anaesthesia (produced by 500 mg/kg i.p. chloral hydrate) was accompanied by a six-fold increase in extracellular striatal AA levels, while negligible changes in DOPAC and 5HIAA occurred. Following complete recovery from anaesthesia, the animals were re-injected with the same dose of anaesthetic which specifically reduced AA levels by 90% (DOPAC levels were unchanged and 5HIAA concentrations slightly reduced). In conscious rats, the neuroleptic haloperidol (1 mg/kg i.p., n = 5) and the minor tranquillizer diazepam (10 mg/kg i.p., n = 5), both considered as behaviourally depressant drugs, reduced extracellular AA levels to 50% of controls. The psychomotor stimulant D-amphetamine (1 mg/kg i.p., n = 5) increased AA levels by 90% over controls. Stress activation of animals (handling for 10 min, n = 10) also produced a transient, significant increase (180% of control values) in this striatal parameter. Taken together with previous reports, our results suggest a close relationship between the state of consciousness and extracellular AA levels in the rat striatum and that this relationship appears to be more correlated to AA as no such clear interdependence was noted between the levels of consciousness and extracellular striatal DOPAC or 5HIAA.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Cognitive impairments induced by triazolam in healthy volunteers: antagonism by a partial inverse agonist of benzodiazepine receptor.

Pharmacological studies revealed that SR 25776 possesses marked stimulant activity characteristic of a partial inverse agonist of benzodiazepine receptor. The effects of SR 25776 500 mg alone and in combination with triazolam 0.25 mg on psychomotor performance and memory were assessed in 8 healthy consenting male volunteers in a double-blind placebo controlled trial. Treatment effects were monitored before and two and half hours following oral medication. The present study suggest that at the studied dose SR 25776 may incompletely antagonize the sedative and amnesic effects of a benzodiazepine agonist without producing marked effects of its own.

Adult↗