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Biomedical subjects

M Bourassa

Publications and source records attributed to M Bourassa.

51 records · Page 3Linked to original sources
PubMed1978

Immunoreactive beta-endorphin in the rat mammotropic transplantable tumor (MtT-F4).

Raised levels of what appeared to be beta-lipotropin (beta-LPH), beta-melanotropic hormone, and beta-endorphin were detected by radioimmunoassay in the plasma of rats bearing the mammotropic transplantable pituitary tumor MtT-F4. The immunoreactivity to anti-beta-endorphin in the assay was displayed by a substance with the molecular weight of beta-LPH, as determined by gel filtration. Isolated cells of MtT-F4 tumor incubated in vitro released immunoreactive beta-LPH and beta-endorphin, with the expected molecular weights, into the incubation medium. These results suggest that the pituitary transplantable rat tumor MtT-F4 secretes peptides structurally related to beta-LPH.

Adrenocorticotropic Hormone↗
PubMed1977

Catecholamines in coronary sinus during exercise in man before and after training.

Coronary patients exercised on an ergometric bicycle before and after physical training. Plasma catecholamines were sampled simultaneously at the arterial and coronary sinus levels and assayed with a radioenzymatic method. The increase in the level of coronary sinus catecholamines exceeded the increase in the arterial level, indicating a liberation of catecholamines by the myocardium and an activation of the peripheral sympathetic fibers during exercise. With high work loads, these values no longer differed, suggesting that the additional increase in circulating catecholamines originate from extra-myocardial stores, presumably the adrenal medulla. Arterial catecholamine levels were significantly correlated with work loads, heart rate, changes in systolic blood pressure, and rate-pressure product. After physical training, arterial catecholamine increases for various work loads were lower; these lower elevations were associated with diminished responses in heart rate and systolic blood pressure, resulting in a lower rate-pressure product. Physical training results in diminished sympathetic responses for a given level of exercise, which could be associated with the clinical improvement of these patients.

Adult↗
PubMed1974

The effect of oxytetracycline on insulin resistance in obese mice.

1. Chronic oxytetracycline treatment was found to improve the insulin resistance of the obese-hyperglycaemic mouse. 2. The improved response to insulin was accompanied by decreased concentrations of circulating insulin and glucose, by a decrease in the lipid content of the liver and by an increase in the insulin-receptor sites of the liver and adipose tissue. 3. The increase in insulin-receptor sites preceded the fall in blood glucose. 4. Comparable studies done on food-restricted animals indicated that although chronic food restriction corrected the hyperinsulinaemia it did not restore the insulin-receptor sites or the hyperglycaemia.

Animals↗
PubMed1965

Vectorcardiographic evaluation of postoperative changes in patients with interatrial septal defect: a review of 55 cases.

The pre- and post-operative vectorcardiograms of 55 patients with atrial septal defect (ASD) are discussed. Forty-nine were of ostium secundum type and six of ostium primum type. The criteria used to study the regression of right ventricular hypertrophy were: in the horizontal plane, the ratio of anterior-over-posterior forces, the right-over-left forces and the rotation of the body of the QRS loop; in the frontal plane, the direction of half-area vector. Using these criteria, 46 out of 49 patients with defects of the ostium secundum type had vectorcardiographic evidence of regression of right ventricular hypertrophy. Marked clinical improvement was also demonstrated in all these patients. The three patients in whom improvement was not demonstrated on the vectorcardiogram had persistence of a cardiac defect. Following surgery two children with ostium primum defects showed no change in the frontal plane, whereas in the horizontal plane a normalization of vectorial forces was observed.

Electrocardiography↗
PubMedDate not supplied

Effects of probucol on vascular remodeling after coronary angioplasty. Multivitamins and Protocol Study Group.

BACKGROUND: We have shown that probucol reduces restenosis after balloon angioplasty. Whether probucol acted via prevention of neointimal formation or improvement in vascular remodeling could not be addressed by angiography and required the use of intravascular ultrasound (IVUS). METHODS AND RESULTS: Beginning 30 days before angioplasty, 317 patients were randomly assigned to receive probucol, multivitamins, combined treatment, or placebo. Patients were then treated for 6 months after angioplasty. IVUS examination was performed immediately after angioplasty and at follow-up in 94 patients (111 segments). The cross section selected for serial analysis was the one at the angioplasty site with the smallest lumen area at follow-up. In the placebo group, lumen area decreased by -1. 21+/-1.88 mm2 at follow-up, and wall area and external elastic membrane (EEM) area increased by 1.50+/-2.50 and 0.29+/-2.93 mm2, respectively. Change in lumen area, however, correlated more strongly with the change in EEM area (r=0.53, P=0.002) than with the change in wall area (r=-0.13, P=0.49). Lumen loss was -1.21+/-1.88 mm2 for placebo, -0.83+/-1.22 mm2 for vitamins, -0.25+/-1.17 mm2 for combined treatment, and -0.15+/-1.70 mm2 for probucol alone (P=0.002 for probucol, P=0.84 for vitamins). Change in wall area was similar for all groups. EEM area increased by 0.29+/-2.93 mm2 for placebo, 0. 09+/-2.33 mm2 for vitamins only, 1.17+/-1.61 mm2 for combined treatment, and 1.74+/-1.80 mm2 for probucol only (P=0.005 for probucol). CONCLUSIONS: Lumen loss after balloon angioplasty is due to inadequate vessel remodeling in response to neointimal formation. Probucol exerts its antirestenotic effects by improving vascular remodeling after angioplasty.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Stimulus-response incompatibility effects on event-related potentials in children with attention-deficit hyperactivity disorder.

In order to test the hypothesis of a response choice deficit in attention-deficit hyperactivity disorder (ADHD) children, event-related potentials (ERPs) were recorded from 30 scalp electrodes in 21 ADHD and 21 normal boys during a spatial stimulus-response compatibility (SRC) task. ADHD children made fewer correct responses than control children, but did not show a larger incompatibility effect on response speed and accuracy. In ERPs, ADHD children had longer N1 latency and larger condition effect on the frontal N2, which would reflect a greater frontal involvement for the correct responses. The ADHD group who performed the SRC task first showed a larger condition effect on an early occipital P3 only, while the ADHD group who performed the SRC task second showed a larger condition effect on a later central P650 component and on a late parietal NSW, as compared with normal controls. These results suggest strategic differences in information processing in ADHD children, rather than a specific deficit.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

ERPs and behavioral inhibition in a Go/No-go task in children with attention-deficit hyperactivity disorder.

In order to study the behavioral responses and the brain inhibition process in children with attention-deficit hyperactivity disorder (ADHD), Event-Related Potentials (ERPs) were recorded from 30 scalp electrodes in 21 ADHD and 21 normal boys during performing a Go/No-go task. ADHD children made fewer correct responses to both Go and No-go stimuli than normal controls. The frontal N2 amplitude was larger for No-go stimuli than Go stimuli in both groups, reflecting inhibition of responding. Smaller N2 amplitudes to No-go stimuli were found in ADHD children, but only when the Go/No-go task was performed after a first stimulus-response compatibility (SRC) task. In addition, the controls exhibited a prolonged N2 only when the Go/No-go task was performed second. However, the ADHD subjects exhibited this prolonged N2 when the task was first, but not when it was second. These results suggest an inhibitory regulation problem rather an inhibition deficit in ADHD children.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

Diagnosis and management of heart failure. Canadian Cardiovascular Society.

Many of the recommendations presented in this consensus report are summarized in Figure 2. All patients with known or suspected heart failure should undergo a detailed history and physical examination. Other causes for the symptoms and/or clinical signs indicative of heart failure should be excluded. Routine biochemical tests, as well as a standard chest x-ray and ECG, should be performed on all patients with heart failure. Precipitating or aggravating causes of heart failure should be eliminated. Patients with potentially surgically correctable lesions, such as constrictive pericarditis, valvular disease or left ventricular aneurysm, should be referred for cardiological evaluation and the appropriate surgery. Patients with ischemic induced heart failure should be assessed for possible revascularization by either angioplasty or bypass surgery. Pending clinical findings and the degree of systolic or diastolic dysfunction present, determined by noninvasive tests, the panel made recommendations concerning the choice of various therapeutic agents. These clinical guidelines have been developed for practising physicians who manage patients with heart failure. The process by which consensus recommendations were developed by the Canadian Cardiovascular Society was based on the principle that guidelines have the best chance of succeeding if they are developed by those who will be using them. Strategies that ensure physicians are aware of the current guidelines, and that their implementation leads to measurable improvement in the diagnosis and management of patients with heart failure must be developed. Consensus reports represent an ongoing process which is subject to revision when further conclusive evidence is obtained by ongoing and future clinical trials.

Cardiac Output, Low↗