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Biomedical subjects

M P Thomas

Publications and source records attributed to M P Thomas.

11 recordsLinked to original sources
PubMed1990

Thermal effects on long-term potentiation in the hamster hippocampus.

Extracellular CA1 pyramidal cell activity was measured at different temperatures in hippocampal slices from the Syrian hamster (Mesocricetus auratus), a hibernator. Control records taken before and after tetanic stimulation of Schaffer collateral/commissural pathways were compared to determine if long-term potentiation (LTP) was established. LTP (an enhancement of the population spike amplitude or population synaptic response following tetanus) was elicited in slices at temperatures above 22 degrees C, but not in slices at temperatures of 20 degrees C. When LTP was established at temperatures above 24 degrees C, however, lowering the temperature to 20 degrees C did not abolish the LTP. Furthermore, when a tetanus was delivered at 20 degrees C and the bath temperature was then raised above 22 degrees C, LTP was established. These results for step changes in temperature suggest that the sequence of cellular mechanisms leading to LTP is activated, but then arrested in slices maintained at a constant temperature of 20 degrees C. Assuming this type of activity in the slice parallels in vivo hippocampal activity, it follows that the ability to elicit LTP in CA1 hippocampal pyramidal cells is lost when the core temperature of an animal entering hibernation falls to 20 degrees C.

Animals↗
PubMed1990

Myocardial infarct size reduction by the synergistic effect of hyperbaric oxygen and recombinant tissue plasminogen activator.

Fasting mongrel dogs underwent hyperbaric oxygen treatment (HBOT), recombinant tissue plasminogen activator (rt-PA) treatment, and simultaneous HBOT and rt-PA treatment following prior experimental left anterior descending coronary artery occlusion for 2 hours. Thrombosis in and around a copper coil was recorded angiographically at regular intervals, and immediately prior to treatment conclusion. Controls (n = 10) were untreated. Group two animals (n = 10) were treated additionally with 90 minutes of HBOT at 2 atm absolute. Group three animals (n = 8) were treated additionally with 50 mg rt-PA over 90 minutes. Group four animals (n = 10) were treated additionally with simultaneous HBOT and rt-PA over 90 minutes. Myocardial injury was determined by a combination of triphenyltetrazolium chloride histochemical staining and by formazan dye extraction. Damage was measured as a percent of left ventricular cross-sectional area studied. HBOT alone restored 35.9% of oxidative enzyme activity (p greater than 0.001). Treatment with rt-PA alone restored 48.9% of enzyme activity (p greater than 0.001). The combination of HBOT and simultaneous rt-PA resulted in 96.9% restoration of oxidative enzyme activity versus the control group (p greater than 0.001).

Animals↗
PubMed1977

Incidence of some surgically correctable congenital abnormalities in South Australia.

A retrospective 5 yr survey of the incidence of some neonatal surgically correctable congenital abnormalities in South Australia has been carried out. Meaningful figures have been obtained for the incidence, in terms of the live birth rate, of obstructive malformation of the gastrointestinal tract, major abdominal wall and diaphragmatic defects, and some anomalies of the genitourinary system. In the main, the incidence of these malformations is similar to that reported from other centers. However the incidence of exomphalos and small bowel obstructions is lower in this series than in others, and the incidence of tracheoesophageal and anorectal anomalies appears to be slightly higher in South Australia than in Victoria. The incidence of diaphragmatic defects, excluding esophageal hiatus, is very similar to that ascertained by the perinatal mortality survey carried out by Butler and Claireaux.

Australia↗