McGill University Thèses et mémoires publiés en 1971

A mathematical model of adaptation within the vestibulo-ocular system is presented. The output of the model is compared with the results from experiments in which 32 human subjects were rotated in, an earth-horizontal plane, and their responses measured. The mean Long Time Constant of the semicircular canals was found to be 15.0 sec (S.E.M. ± 0.78) and the mean adaptation Time Constant was found to be 73.4 see (S.E.M. ± 3.54). Half the subject population were fighter pilots of the Canadian Armed Forces, and their Vestibular Function was found to be statistically indistinguishable from that of non-flyers. [...]  Lire la suite

An investigation was undertaken to determine the feasibility of using rabbit leukocytes in the capillary migration technique. A procedure employing gelatin sedimentation and sucrose density gradient centrifugation was developed for harvesting appropriate white cell populations. Significant inhibition of migration was obtained when the cells from animals immunized with killed mycobacteria were tested with particulate antigen. PPD failed to give similar results under the same conditions of experiment. Migration inhibition was also obtained with cells harvested from animals immunized with ovalbumin. No conclusive results, however, were obtained in attempts to induce in vitro reactivity towards keyhole limpet haemocyanin. In those animals …  Lire la suite

Patterns of extracellularly-recorded, stationary, background impulse sequences, from individual cervical nerve sympathetic preganglionic units (SPU), have been systematized by time series analysis (interval histogram, IH; autocorrelogram, ACG). Experiments were conducted on anaesthetized (Nembutal, 30 mg/kg) or unanaesthetized (decerebrate) cats - thoracotomized, paralyzed (flaxedil, 8 mg/kg) and artificially ventilated. On the basis of the occurrence and properties of discharge in neuraxially intact and spinal preparations, and the influences of antidromic stimulation, qualitative models are proposed, of SPU spike initiation by a random threshold crossing process (set up by activity in many, independent, converging presynaptic inputs), with firing contiguity limited by postimpulse …  Lire la suite

Antibodies to human growth hormone were detected in 13 patients on long term HGH therapy for (2-7 years) by using immunofluorescence methods. No immunofluorescence was observed in human pituitary acidophils, however, hog pituitary acidophils showed strong fluorescence in all the thirteen patients studied when undiluted sera were used. On diluting the sera 1 to 8 immunofluorescence was inhibited completely in 4 patients who showed no binding to iodinated PGH. Acidophils stained were both somatotrophs and carminophils. Complete inhibition of fluorescent staining was only observed when these sera were incubated with both PGH and PLR and then used for immunofluorescent staining.  Lire la suite

This study was an exploratory attempt at isolating some of the characteristics which distinguish participants in low-income citizens' group from non-participants when both groups are drawn from the same geographic and socio-economio population.  Lire la suite

This investigation has been undertaken to study changes in high energy phosphate metabolism of the canine intestine following hemorrhagic shock. The information on energy metabolism in the intestine is scarce, necessitating extensive studies into normal metabolic properties of this tissue. Respiration of intestinal homogenates was not limited by the level of ADP, but it was limited by the level of cytochromes. These results indicated that oxidative phosphorylation in intestinal mucosa is loosely coupled, a fact that was supported further by the lack of effect of DNP on endogenous respiration. In studies with DNP and NaF, the increased turnover of ATP-phosphate …  Lire la suite

Experimental systems were established to study events occurring during the serum bactericidal reaction. These events are initiated within the first five minutes as shown by the effect of EDTA on phosphorus release. Lipopolysaccharide inhibited this reaction suggesting that the lipopolysaccharide-lipoprotein membrane was the primary target. RNA and DNA synthesis was affected shortly after as shown by incorporation of 3H-uridine and 3H-thymidine, respectively. Incorporation of glycerol-2-3H into membrane lipid ceased after 25 minutes probably due to formation of lesions as indicated by decrease in optical density. Respiratory function (measured by manometric techniques) and protein synthesis (measured by incorporation of 14C-leucine) were …  Lire la suite

The cardio-respiratory effects of a thoracic epidural anaesthetic as is given for pain relief following upper abdominal surgery were examined in thirteen surgical patients studied in the immediate pre-operative period, following an overnight fast and without premedication. The focus of interest was on its effects on FRC and on gas exchange (measured as A-aDO2 and QS/QT%), which have not been previously reported. All subjects were given 10 ml/Kg glucose in saline I.V. during the pre-epidural period. Lidocaine 1.5% was used in all cases, plain lidocaine for the first eight and lidocaine with epinephrine 1/200,000 in the other five subjects. This …  Lire la suite

This thesis concerns studies of arterio-arterial counterpulsation, a mechanical method advocated for support of failing circulation in cardiogenic shock. Its experimental rationale is reviewed and the results of experiments, designed to determine its safety and effectiveness for prolonged application (4 hours), are presented. The findings in normal dogs demonstrated that counterpulsation was well tolerated. It maintained normal cardiac output, arterial pressure and peripheral circulation for three hours with slight deterioration in the final hour. These parameters correlated with a normal arterial lactate concentration during the first three hours. Plasma hemoglobin and blood gases did not change significantly.  Lire la suite

Renal allografts were performed in dogs presensitized by 3-5 exchange skin grafts. Dogs were grouped in pairs, control and treated with sulfinpyrazone (125 mg/kg b.w.), a platelat release inhibitor. Urine flow for the control group was 7.5 hours and for the treated group was 33.1 hours. SeriaI determinations of renal artery and vein platelet and WBC counts showed little change from control in the treated group. However, in the control group there was a considerable fall in renal vein platelet counts at the time of anuria. No significant differences in WBC counts could be found in either group. Light microscopy …  Lire la suite

Steinberg, Blema (Supervisor)  Lire la suite

Bone marrow lymphoid cells ranged in nuclear diameter from 5.0 to 15.0 microns in smears. Smaller cells were predominantly pale; larger ones predominantly basophilic. Nearly all cells in DNA synthesis (determined by isotope uptake) were greater than or equal to 8.0 microns.  Lire la suite

Afferent transmission in the dorsal column - lemniscal sensory pathway of the decerebrate cat was recorded as evoked potentials during acute changes in brain tissue PC02, induced by the inhalation of 2 to 20% CO2. CO2 has a mainly depressant action on overall transmission from a forelimb nerve to the midbrain medial lemniscus, and on the excitability of the presynaptic afferent terminals and postsynaptic relay neurones in the cuneate. From an input/output analysis, correlating trans-synaptic responses at the medial lemniscus and antidromic responses at the nerve, it was concluded that (i) the efficiency of synaptic transmission at individual active synapses …  Lire la suite