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Biomedical subjects

I A Silver

Publications and source records attributed to I A Silver.

123 records · Page 7Linked to original sources
PubMed1971

Excitation of certain posterolateral hypothalamic units by cyclopropane and ether.

1. Extracellular activity was recorded from single units in the posterolateral hypothalamus in nineteen cats before, during, and after the administration of the inhalation anaesthetics cyclopropane, diethyl ether and halothane.2. Unit discharge was significantly increased by 25-50% cyclopropane in eighteen of the forty-four cells tested with this anaesthetic, and in seven of fourteen cells tested with diethyl ether. This excitatory effect was associated with cortical EEG suppression.3. The remaining cells tested were depressed by cyclopropane or ether, and this also occurred during halothane administration.4. Excitation of certain cells in the posterolateral hypothalamus is discussed in relation to the increased preganglionic sympathetic activity evoked by cyclopropane and ether.

Action Potentials↗
PubMedDate not supplied

Sweep potential polarography and multiwire surface tissue electrodes.

A multitipped seven barrelled platinum electrode for brain surface oxygen measurements during neurosurgery is described. Its performance has been examined when employed under conditions of sweep potential polarography. Although there is no plateau within the oxygen polarogram, the electrode displays linear performance within the physiological range, gives reproducible results in practice, has an acceptable temperature coefficient and a fast response time.

Cerebral Cortex↗
PubMedDate not supplied

Effect of hypotension induced by ATP and adenosine on brain surface oxygen tensions in the sheep.

A multitipped oxygen electrode has been used to measure cortical surface oxygen tensions in the sheep. A histogram of the pattern of supply of oxygen to cortical tissue within the microcirculation during normal conditions is presented. Systemic arterial pressure was reduced to a mean of 30 mmHg with either Adenosine or ATP, and further oxygen tension measurements undertaken. The oxygen histogram was shifted to the left in these circumstances, and there was an increase in the frequency of occurrence of very low tissue oxygen tensions. This suggests that the use of these agents to induce profound hypotension may be associated with significant ischaemia within the microcirculation.

Adenosine↗
PubMedDate not supplied

Effect of carotid artery ligation and infusion of fluosol FC-43 emulsion on brain surface oxygen tensions.

In eight rabbits, the common carotid artery was ligated and multiple estimations of brain surface oxygen tension performed using a seven barrelled mini-electrode. In five rabbits ligation of the carotid artery resulted in impairment of cortical oxygenation. The remaining three rabbits showed no impairment in the supply of oxygen to the cerebral cortex after carotid occlusion. In the five rabbits who displayed a reduction in oxygen supply after carotid ligation, ventilation with 33% oxygen after the infusion of 15 ml/kg of Fluosol FC-43 produced an improvement in cortical oxygenation in only three of the five rabbits. When these animals were ventilated with 100% oxygen after carotid ligation and Fluosol infusion, oxygen supply in all five was commensurate with or greater than that during control conditions.

Animals↗