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Biomedical subjects

J A Gray

Publications and source records attributed to J A Gray.

At least 19 recordsLinked to original sources
PubMed1979

The analysis of sound by the sprat ear.

In the acoustico-lateralis systems of vertebrates the individual hair cells are usually polarised in their responses to displacements of the liquid in which they lie, and are often arranged in back-to-back pairs or groups with different polarities. A simple example to investigate, mechanically as well as electrically, is the utriculus of the sprat (Clupea sprattus L.). The acoustico-lateralis system of the sprat and other clupeids has two partly gas-filled bony bullae which transform pressure changes into liquid displacements capable of stimulating the sense organs of the ear and lateral line. With its related structures the utriculus is a very sensitive sound pressure detector which has one population of receptors that respond to the compressions and another that respond to the decompressions of a sound wave. We now give additional evidence that this type of organisation is unlike that of the mammalian cochlea in being specialised more for the detection of phase/time relationships than for frequency analysis.

Animals↗
PubMed1979

Septo-hippocampal connections and the hippocampal theta rhythm.

Recordings were made of spontaneous hippocampal theta activity in free-moving rats, before and after a variety of lesions. Three recording sites were used to monitor activity in the dorsal hippocampus, the ventral hippocampus, or close to the site of the hippocampal flexure. Electrolytic lesions were made in the medial septal area or the dorso-lateral septal area; surgical transections were made of the fimbria or dorso-medial area of the fornix. Following lesions restricted to the medial septal area, theta was abolished throughout the hippocampus; after lesions restricted to the dorso-lateral septal area theta was retained. Fimbria lesions abolished it in the dorsal, but not the ventral, hippocampus. In some subjects the hippocampal formation was subsequently stained for cholinesterase: cholinesterase staining loss was generally associated with theta loss, but this was not clear at the flexure recording site. It was confirmed that theta is dependent upon the integrity of the medial septal area. It was concluded that damage to hippocampal afferents from the septum does abolish theta, while damaging the feedback efferents does not.

Animals↗
PubMed1979

Effect of runway training on rat brain tyrosine hydroxylase: differential effect of continuous and partial reinforcement schedules.

Previous experiments have implicated ascending noradrenergic systems in the development of the behavioural responses to different patterns of reward. In this report food deprived male Sprague--Dawley rats were trained to run a straight alley for good reward on a continuous reinforcement (CRF) or a partial reinforcement (PRF) schedule. Tyrosine hydroxylase measured in a partially solubilized preparation from hippocampus and hypothalamus at the end of acquisition was not different from controls, indicating that enzyme induction does not occur during either training schedules. However, hippocampal synaptosomal tyrosine hydroxylation rates from the CRF group was significantly higher than from either the PRF group or the handled controls. This indicates that at the end of the acquisition schedule the noradrenergic projection to hippocampus was more active in the CRF group than with the PRF group or the handled control.

Animals↗
PubMed1979

Emotionality in male and female rodents: a reply to Archer.

Archer (1979) has complained that his criticisms (Archer, 1971, 1973, 1975) of Gray's (1971 a, b) views on emotionality and on sex differences in fearfulness in rodents have not been answered. These criticisms are shown to lack substance and to depend on confused arguments and misleading reviews of the literature.

Animals↗
PubMed1979

Choosing priorities.

Dr Gray leaves us with a question at the conclusion of his article--how should we choose priorities? He says that the debate so far has been mainly on what we should choose, but perhaps we should consider how to choose even more. Under the various subheadings of Criteria, Principles and Persons Dr Gray sets out the pros and cons of the arguments in the priority debates and tries to offer some more specific guidelines to offset the criticism that the government's priority discussions have been too generalised. Yet this is a difficult task when everyone's priorities are so different.

Cost-Benefit Analysis↗
PubMed1979

Antibacterial prophylaxis--a clinician's view.

The principles of antibacterial prophylaxis and its advantages and disadvantages are reviewed. Controlled trials have shown chemoprophylaxis to be beneficial notably in preventing recurrences of rheumatic carditis and urinary infections and in controlling sepsis after cardiac and hip joint surgery and mid thigh amputations. The recently introduced metronidazole prophylaxis for gastrointestinal and gynaecological operations appears highly effective. The use of prophylaxis is briefly discussed in other situations where its value is less certain or where, in the author's opinion, it is contraindicated.

Adult↗
PubMed1979

Single alternation with water reward:effects of sodium amobarbital on two strains of rats selectively bred for high and low emotionality.

The action of sodium amobarbital is studied during the patterning effect in rats selectively bred for low and high emotionality. The drug disrupts patterned running in the goal section of the alley in Maudsley non-reactive but not in Maudsley reactive rats for the last five trial-pairs. Sodium amobarbital also affects the behavior of these strains in a differential manner, in start and run sections, during the first trial-pair. The results show that a function-related physiological change has taken place in the Maudsley strains of rats.

Amobarbital↗
PubMed1978

Housing, health, and illness.

Cases referred to a community physician in his role as medical adviser to a housing authority were reviewed. A new system of classifying health problems was devised because conventional diagnostic classification was found to be inappropriate. The effectiveness of medical intervention was apparently low, since only 29 out of 612 (4.7%) applications for rehousing on medical grounds were successful. The effectiveness of the community physician's role was limited by the available resources and the number of cases he could take before the housing committee. It is proposed that the use of medical resources for intervention in such cases is acceptably efficient, though this proposal is based on value judgement rather than on economic grounds. Doctors should be concerned in improving housing conditions, which are still unacceptably poor in many parts of Britain, in the interests of improving general standards of public health.

Community Health Services↗
PubMed1978

The effects of pre-admission antibiotics on the bacteriological diagnosis of pyogenic meningitis.

To assess the effects of pre-admission antibiotics on the accuracy of bacterial diagnosis in pyogenic meningitis, the case records of 154 patients admitted to an infectious diseases unit during a 10-year period (1966-1975) were reviewed. The causative organism was identified in 140 patients (91%). Although 63 patients had received antibiotics before admission, a bacteriological diagnosis was still possible in 57 of these (90%).

Adolescent↗
PubMed1977

A difficult decade.

Explore the source record for details and available documents.

Community Health Nursing↗