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Biomedical subjects

P C Pearce

Publications and source records attributed to P C Pearce.

32 records · Page 2Linked to original sources
PubMed1989

A method of remote physiological monitoring of a fully mobile primate in a single animal cage.

A system was designed to allow the physiological monitoring of a fully mobile, unstressed baboon (Papio anubis) in a single animal cage for the purpose of measuring the changes occurring in a hyperbaric environment. It was required to operate for at least three months, both inside a pressure chamber and outside, and to measure the following parameters: electroencephalogram (EEG, three channels), electrooculogram (EOG), electromyelogram (EMG, two channels), electrocardiogram (ECG), arterial blood pressure, respiration and body temperature. Also in the system were catheters through which blood samples could be taken and intravenous drugs given. The overall system consisted of a harness and jacket, an umbilical and back pack, a combined electrical and fluid transmission swivel and a monitoring implant and catheters.

Animal Welfare↗
PubMed1989

Sodium valproate interactions with the HPNS: EEG and behavioral observations.

A new baboon model was used to investigate the therapuetic effect of sodium valproate on the high pressure neurologic syndrome (HPNS). A hyperbaric chamber was used to achieve environmental pressures of 61 ATA, over a 5-h period. Eight animals underwent two compressions, a control and a valproate-treated compression (half the animals had valproate on the first compression). Mild signs of HPNS (e.g., paw and limb tremor) were first observed at approximately 20 ATA. More severe signs (e.g., whole body tremor, myoclonus, and vomiting) were observed above 40 ATA. Sodium valproate was administered during the compression phase and for 2 wk previously. It was effective at the higher pressures above 41 ATA in reducing the severity of the signs of HPNS. The major effect of pressure on the EEG was to increase alpha and theta wave amplitude in a linear manner. Alpha wave amplitude was reduced by sodium valproate.

Animals↗
PubMed1989

Cochlear degeneration in minipigs after repeated hyperbaric exposures.

Auditory function and cochlear pathology were investigated in 4 minipigs subjected to compression to 4 ATA, held for 1 h, and decompressed using a standard schedule (Blackpool Tables) on 21 occasions. Three minipigs were used as controls. Brainstem auditory evoked response testing was carried out after the last hyperbaric exposure and showed no response bilaterally in 3 and unilaterally in 1 of the test animals. Light microscopy demonstrated a loss of hair cells throughout the cochlea in all the compressed animals; in one the tectorial membrane was detached and adherent to Reissner's membrane. Vestibular changes were confined to the saccule. Hemorrhage was not a prominent feature. On scanning electron microscopy the pathologic changes included missing hair cells and fused and giant stereocilia. Possible causes of the pathology include barotrauma or direct effects of repeated compression and decompression on the inner ear, or both. The compression-decompression profile used was one that is thought to be safe for compressed air workers who are repeatedly exposed to hyperbaric conditions.

Animals↗
PubMed1989

Physiological effects of etorphine, acepromazine and xylazine on the black fallow deer (Dama dama).

Confined and unconfined fallow deer (Dama dama) of the black variety kept at Whipsnade Park were sedated with etorphine in combination with acepromazine, or xylazine or both, with or without atropine. Induction, sedation and recovery times were recorded. During the period under sedation, systemic and pulmonary arterial pressures, electrocardiographs, body temperature, arterial blood gas pressures and pH, packed cell volume and plasma electrolytes and enzymes were monitored. In both groups, and with all drug combinations, heart rates (except where atropine was used and respiratory rates were depressed, pulmonary arterial pressures were elevated, and blood oxygen tension and pH lowered compared with interspecies norms. In confined animals, systemic arterial pressures were depressed. Unconfined animals and animals in which atropine was used showed higher and more varied systemic arterial pressures and more varied heart rates. Cardiac arrests occurred in eight animals, five during induction and three during sedation, one of which was revived with oxygen. Severe arrhythmia occurred in an animal in which atrioventricular block was confirmed and reversed by oxygen treatment.

Acepromazine↗
PubMed1989

Physiological effects of etorphine, acepromazine and xylazine in the scimitar horned oryx (Oryx dammah).

Scimitar horned oryx (Oryx dammah), kept under confined and unconfined conditions were immobilised with etorphine in combination with acepromazine or xylazine or both, and with xylazine alone. Both groups of animals were successfully sedated with etorphine and xylzine, with or without acepromazine, although hypothermia and mild hypoxaemia and a fall in packed cell volume were frequently noted. Xylazine alone produced a dose dependent degree of sedation in semitame subadult animals kept in confinement, but only slight depression in their wild, unconfined counterparts. If xylazine was not included in the immobilising mixture induction was traumatic and full sedation not achieved. Heart rates and arterial pressures (systemic and pulmonary) were also monitored but no remarkable changes were noted. The only abnormalities in blood biochemistry were raised aspartate transminase and creatine kinase. Ruminal regurgitation could be a major problem if endotracheal intubation was not achieved early in the procedure.

Acepromazine↗
PubMed1988

The importance of membrane stabilization in protecting the developing rat myocardium from the actions of triac.

Administration of triiodothyroacetic acid (triac) to pregnant rats produces cardiac hypertrophy and myofibrillar disarray in the hearts of the newborn offspring. Previous experiments have shown that concurrent administration of dl exprenolol or dl or d propranolol prevent the disarray but not the hypertrophy, suggesting that membrane stabilization and not beta-adrenergic blockade may be responsible for modifying the actions of triac. In order to clarify this, further experiments have been carried out whereby timolol, a beta-blocking agent with minimal or no membrane stabilizing activity, and procainamide, a pure membrane stabilizing compound, have been administered with triac. Timolol had no effect, but procainamide reduced the level of disarray and the hypertrophy to a minor degree. The results have thus confirmed the proposal that membrane stabilization is of major importance in modifying the actions of triac.

Animals↗
PubMed1986

Changes in red cell volume distribution frequency after acute blood loss in goats (Capra hircus).

Red blood cell volume distribution frequency, red cell counts, packed cell volumes and reticulocyte counts were monitored during recovery from severe haemorrhagic anaemia in goats. During the first three weeks after haemorrhage there was a small transient reticulocyte response and the cells produced were significantly larger than normal. These large cells persisted in the circulation as a distinct subpopulation of macrocytes, so that the rate of red cell production during this phase could be measured. The findings suggest that red cell volume distribution measurement is a useful method for retrospective diagnosis of severe haemorrhage and for monitoring recovery. The technique also provided a means of assessing erythropoietic activity in a species in which the reticulocyte response to red cell loss is minimal.

Animals↗
PubMed1983

Effect of triac and beta-adrenergic blocking agents on the myocardium of developing rats.

Triiodothyroacetic acid, triac, when given to rats during pregnancy, causes hypertrophy and intracellular disarray in the hearts of their offspring and concurrent treatment with dl propranolol can prevent the latter abnormality. Further experiments have been carried out to test the effect of dl oxprenolol and d propranolol on triac-induced myofibrillar disarray. Administration of dl oxprenolol at the same time as triac prevented disarray but a higher dose than that of dl propranolol was required to produce this effect. Disarray was also prevented by d propranolol. Selective consideration of the membrane stabilising, beta blocking and agonist activities of dl oxprenolol and d and dl propranolol leads to the conclusion that although direct or indirect beta stimulation by triac may play a small part in its disruptive effect on the developing myocardium, its main deleterious action can be blocked by membrane stabilisation.

Animals↗
PubMed1979

Is there a future for single photon emission tomography?

Emission tomography has the potential to be developed into a clinically useful technique. Its clinical applications, however, will be limited and not in the main stream of space occupying disease detection but in the definition of quantitative information particularly relevant in those disease processes where the metabolic component is the most important one. Special purpose designed instrumentation may prove to be the best of several possible compromises.

Elementary Particles↗
PubMed1978

Validation of "transit renography" for the determination of the intrarenal distribution of plasma flow: comparison with the microsphere method in the anaesthetized rabbit and pig.

1. The spectrum of transit times of sodium o-iodohippurate (Hippuran) through the kidney can be derived from an 131I- (or 123I-) labelled Hippuran renogram by deconvolution. In the rabbit and pig, as has previously been shown in man, the frequency distribution curve for the transit times was bimodal. Since the transit time is likely to be proportional to the nephron length, the area of the first mode is likely to represent plasma flow to the shorter outer cortical nephrons whereas the delayed mode represents flow to the long juxtamedullary nephrons. 2. This interpretation was tested by simultaneously comparing renography with the microsphere method of measuring intrarenal plasma flow distribution in 12 rabbits and two pigs with a variety of anaesthetics. A close agreement was found between both methods for the percentage of plasma flow distributed to the outer cortical nephrons, thus supporting the use of "transit renography" to determine the intrarenal distribution of plasma flow.

Anesthetics↗
PubMed1977

High-quality, high-throughput, early whole-body bone scanning.

99mTc-IDP allows for high-quality, high-throughput and early whole-body bone scanning. Whole-body bone scans obtained at 30 min after intravenous administration of the tracer were compared with the standard and delayed 180 min p.i images. A subtraction technique allowed for the anlysis of the 30 min scans and it was found that in both types of investigation the same clinical information was present. This procedure will therefore increase considerably the throughput of whole-body bone scans in a busy department of nuclear medicine. It is however inadequate for detailed analysis of the skeleton (evaluation of benign bone disease).

Adult↗