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Biomedical subjects

M Palmer

Publications and source records attributed to M Palmer.

At least 217 records · Page 12Linked to original sources
PubMed1982

Evidence for genetic correlation of hypnotic effects and cerebellar Purkinje neuron depression in response to ethanol in mice.

In the present study, we compared phenotypic differences in behavioral and neurophysiological responses to acute ethanol administration among eight inbred strains of mice. Genetic variation for behavioral sedation, as measured by loss of the righting reflex (sleep time) after a hypnotic dose of ethanol, was shown to be present among the inbred strain population. In addition, a large genetic component of variation in the depressant action of ethanol on the spontaneous discharge of cerebellar Purkinje neurons was found. Results from an analysis of covariance of the behavioral and electrophysiological phenotypes, measured on each mouse among the inbred strains, provided strong evidence for a high genetic correlation between sleep time and inhibition of cerebellar Purkinje neuron discharge in response to acute ethanol administration. Taken together with our previously reported data on ethanol-induced electrophysiological changes in selectively bred lines, the results described here strongly support the hypothesis that the cerebellar Purkinje neuron is one important locus for the acute soporific effects of alcohol.

Animals↗
PubMed1982

The spatial organization of the hierarchical proliferative cells of the crypts of the small intestine into clusters of 'synchronized' cells.

A statistical analysis of the distribution of [3H]TdR-labelled cells in longitudinal and transverse sections of crypts from the ileum of the mouse, indicated that there was a strong tendency for labelled or unlabelled cells to be associated in short vertical runs and lateral clumps, suggesting the presence of clusters of labelled cells on the sides of the crypts. A model is discussed for the cellular spatial organization of the crypt that proposes a vertical alignment of the cells within branches of the proliferative cell lineage. The model would predict vertical alignment of partially synchronized cells as well as some lateral clumping. In the present studies mitoses were not observed at higher levels in the crypt than labelled (S phase) cells. This observation would be predicted by the non-random spatial organization suggested by the model. The model would also make certain predictions concerning cell migration. These are discussed in relation to cell migration studies which include evidence that migration continues in the absence of mitotic activity.

Animals↗
PubMed1981

Differential electrophysiological and behavioral responses to optically active derivatives of phencyclidine.

Dextro- and levorotatory isomers of 1-(1-phenylcyclohexyl)-3-methylpiperidine (PCMP) were synthesized. Both isomers inhibited spontaneous cerebellar Purkinje neuron firing when applied locally by pressure ejection. This effect was dose-dependent, with the (+)-isomer about 5--7 times more potent than the (-)-isomer. Both isomers also depressed rotarod performance in mice. Again, the (+)-isomer was about 5 times more potent than the (-)-isomer. Both rotarod performance and Purkinje cells discharge were depressed maximally 10--15 min after i.p. injection of drug. Our results suggest a correlation between behavioral performance and central neuron electrophysiological activity and suggest that the central actions of PCP or its derivatives are probably mediated at one locus, by a stereospecific mechanism.

Animals↗
PubMed1980

Electrophysiological correlates of ethanol-induced sedation in differentially sensitive lines of mice.

Acute electrophysiological effects of ethanol were studied in two lines of mice that differ markedly in their response to the soporific effects of systemic alcohol administration. Cerebellar Purkinje neurons from the genetic line that had long sleep times were one to two orders of magnitude more sensitive to the depressant effects of locally administered ethanol than those from the line that had short sleep times. The data suggest that there are genetically determined specificities in the acute effects of ethanol on central neurons and that such specificities might be used to determine which regions of the cerebellum participate in differences in behavioral responses to this substance.

Action Potentials↗
PubMed1980

Electrophysiological interactions of enkephalins with neuronal circuitry in the rat hippocampus. I. Effects on pyramidal cell activity.

Effects of enkephalins on hippocampal pyramidal cell activity were studied in situ and in the in vitro hippocampal slice. Active enkephalin derivatives produced a dose-dependent naloxone-reversible excitation in both preparations whereas inactive enkephalin derivatives had no effect. Several different types of experiments, carried out in the slice, strongly suggest that this excitation is due to blockade of inhibitory pathways. First, when the pyramidal cell population spike is increased during enkephalin administration, no change is seen in the simultaneously recorded EPSP. Second, the magnitude of the enkephalin effect is highly correlated with the amount of inhibition, as judged by paired-pulse stimulation, initially present in the slice. Third, if inhibitory pathways are depressed by a brief period of hypoxia, enkephalin has little effect. Finally, enkephalin responses are mimicked by picrotoxin, which selectively antagonizes inhibitory input to the pyramidal neuron. Since enkephalins do not block the effects of GABA, the putative inhibitory transmitter, these data suggest that opioid peptides depress the inhibitory interneurons and disinhibit the pyramidal cells.

Animals↗
PubMed1979

Spinal-cord compression in myeloma.

Clinical records of 47 patients in whom spinal-cord compression was the presenting feature of plasma-cell myeloma were analysed retrospectively. Patients were referred during 1954-78. Median survival was 30 months and prognosis was best for those in whom the site of cord compression was the thoracic region. Early laminectomy and decompression followed by adequate radiotherapy resulted in complete or good partial response in over a third of patients who presented with complete paraplegia. Improvements in supportive care and more effective chemotherapy allow spinal-cord compression in myeloma to be treated promptly and vigorously, thus improving duration and quality of survival in a substantial proportion of patients.

Female↗
PubMed1979

A prospective randomized trial of vagotomy in chronic duodenal ulceration.

In a prospective, randomized trial, 76 patients with duodenal ulceration treated by truncal vagotomy and pyloroplasty were compared with 77 patients who underwent highly selective vagotomy. A total of 149 patients was followed up for from 1 to 4 years, the average follow-up period being 2.6 years. There was no operative mortality and no significant difference in postoperative morbidity between the two groups. The incidence of recurrent ulceration was greater after highly selective vagotomy, but this difference was not statistically significant. The clinical results were comparable in each group, and although the incidence of diarrhoea and dumping was greater after vagotomy and pyloroplasty, this difference was not statistically significant.

Adult↗
PubMed1978

Management of congenital adrenal hyperplasia. Urinary steroid estimations--review of their value.

A retrospective study was made of 16 children with 21-hydroxylase-deficient congenital adrenal hyperplasia of the salt-losing variety, who were treated with fludrocortisone and prednisone and were in good health during the period under review. The height velocity of the children was subnormal, height achievement was poor, and their bone ages retarded. Urinary 17-oxosteroid and pregnanetriol excretion were used to monitor the therapy of the children and these data have been related to growth velocities. In spite of urinary steroid figures in excess of those published as desirable for monitoring therapy, the children failed to grow properly, probably as a result of glucocorticoid overdosage. Published urinary steroid criteria are considered too strict and in order to achieve them one would need to give unnecessarily high doses of steroid. Regular measurement of height velocity and skeletal maturation rate are better indicators of therapeutic control and should lead to more satisfactory growth and ultimate height.

17-Ketosteroids↗
PubMed1976

Distribution of survival times of 12,000 head and neck cancer patients who died with their disease.

The lognormal parametric statistical model can provide, for groups of carcinoma cervix patients, good estimates of long-term survival fractions several years earlier than would otherwise be possible. The present paper extends this model work to head and neck cancer by using a minimum chi-squared test for goodness of fit (P greater than 0-05), to study the distribution of survival times of patients who died with their cancer present. Some 12,000 case histories were available from 7 hospital registries, 4 regional cancer registries and one national registry (the OPCS). All histories were followed up for at least 10 years subsequent to treatment and could be grouped into one of 8 cancer sites: antrum, floor of mouth, larynx, nasopharynx, pyriform fossa, post cricoid, tonsil and tongue. The theoretical distributions investigated were the lognormal, negative exponential and skew exponential. The results showed that the lognormal provided the best overall fit to the data, although the range of optimum values for the lognormal parameter, S, differed with cancer site. The optimum range did, however, usually include the value S=0-45. These results will now permit the second stage of validation of the lognormal model to proceed for head and neck cancers.

England↗