Biomedical subjects

S Evans

Publications and source records attributed to S Evans.

At least 361 records · Page 20Linked to original sources

PubMed1976

Effect of serotonin on brown adipose tissue and on its sympathetic neurons.

Previously we have shown that there are two types of sympathetic neurons in the rat interscapular brown fat-pad: long adrenergic neurons with cell bodies located in the paraspinal ganglia and short adrenergic neurons with cell bodies located within the pad itself. The present studies examine 1) the uptake of [3H]norepinephrine by these neurons, 2) the effect of serotonin on release of the catecholamine, and 3) the metabolic action of serotonin on brown fat. [3H]norepinephrine uptake from the medium in which brown fat slices are incubated is linear with time up to 90 min. This uptake is blocked by both cocaine and imipramine. As these drugs block uptake by sympathetic neurons, the [3H]norepinephrine is probably taken up by neurons and not by some other cell in the pad. Serotonin creatinine sulfate, but not creatinine sulfate, promotes the release of the catecholamine from these neurons. Serotonin also exerts a norepinephrine-like metabolic effect on slices of normal brown fat. It stimulates lipolysis and inhibits lipogenesis. Serotonin has no effect on isolated brown fat cells or on slices of reserpinized tissue. It also does not potentiate the action of norepinephrine on these last two preparations. Therefore serotonin's action on brown fat is mediated by norepinephrine-containing stromal cells. The data suggest that the rat brown fat-pad has sympathetic neurons that can take up norepinephrine and that serotonin exerts its metabolic effect by stimulating the release of norepinephrine from these neurons.

Adipose Tissue, Brown↗

PubMed1975

Histochemistry of trauma after electrode implantation and stimulation in the hippocampus.

Electrodes were implanted into the rat hippocampus in both hemispheres for increasing periods of up to 60 days, and the effects of trauma and electrical stimulation of enzymes controlling cell metabolism in the region of implantation were examined and assessed in relation to studies on humans. In the unstimulated hippocampus as a control, enzyme changes were mainly confined to a narrow area of tissue damage surrounding the electrode. The enzyme changes in response to trauma varied widely; some enzymes controlling tissue respiration showed early and rapid changes, increasing in hyperactive, swollen glial cells and vascular endothelium and decreasing in nerve cells and neuropile. Acid phosphatase activity also increased rapidly in glial cells; other phosphate-releasing enzymes increased more gradually with time. A turning point in these chages was apparent between 25 and 40 days, followed by a reversion to more normal levels at 60 days. Electrical stimulation of the hippocampus in the contralateral hemisphere produced no detectable enzyme changes from those of the unstimulated hippocampus.

Acetylcholinesterase↗

PubMed1975

Disposition of disodium cromoglycate administered in three particle sizes.

1 Disodium cromoglycate (DSCG) was administered in three particle sizes to five human subjects. 2 Urinary excretion of DSCG, as a proportion of the dose, was highest following small particles; the lower values recorded following intermediate-sized and large particles were similar. 3 DSCG deposited in the mouth was highest following large particles; the lower values recorded following intermediate-sized and small particles were similar. 4 The data were examined in relation to the recent observation that the protective effect of small particles of DSCG is dramatically superior to that of large particles.

Adult↗

PubMed1975

Assay of 7-hydroxychlorpromazine, and failure to detect more than small quantities, in plasma of responding schizophrenics.

A method for the assay of 7-hydroxychlorpromazine in biological fluids is described. The stages of the method are extraction into ether, back extraction into acid, alkalinisation and further extraction into ether, evaporation of the extract to dryness, and gas-chromatography of the extracted material as a silylated derivative using conditions previously described for chlorpromazine. The method is applicable to certain other hydroxylated chlorpromazines, but it is not superior to existing methods for the assay of nonhydroxylated analogues. Only small quantities of 7-hydroxychlorpromazine were detected in the plasma of schizophrenics showing a satisfactory clinical response, even when the compound was present in urine, providing strong evidence that the presence of 7-hydroxychlorpromazine in blood is not a pre-requisite of successful therapy.

Animals↗

PubMed1975

Herpesvirus-induced availability of host DNA to exogenous endonuclease.

Deoxyribonuclease I penetrates herpesvirus-infected L cells and degrades host DNA without interfering with viral multiplication. The DNA of uninfected control monolayers of L cells, disrupted by scraping, is similarly attacked. In contrast, undisturbed L cells are not affected. This suggests that altered cell membrane permeability allows the nuclease to enter the cell, thereby permitting access of exogenous deoxyribonuclease to cellular DNA.

Animals↗

PubMed1974