Showing papers by "Université de Montréal published in 1969"

The pluricausal cardiopathies

Abstract: The very fact that scientists of so many countries have contributed to this monograph on “metabolic” cardiopathies bears witness to the great change in outlook that has taken place in the interpretation of the pathogenesis of heart disease during the last decade. Barely eight years ago, in September, 1959, at the International Symposium on Arteriosclerosis and Coronary Disease in Mexico City, I tried to prove that infarct-like cardiac necroses can be produced without vascular obstruction, e.g. by combined treatment with corticoids and electrolytes or corticoids and stress; at that time, with the notable exception of Dr. Sodi-Pallares, few of the participants were prepared to believe that such metabolic factors could play a role in the genesis of “true” cardiac infarcts in man. Although the functional effect of many electrolytes upon the heart had long been known, the finding that sodium increases and potassium and magnesium diminish the susceptibility to cardiac necrosis was also received with the greatest reserve. Seemingly even more incongruous were the observations showing that many essentially distinct experimental cardiopathies (characterized by hyalinization, calcification, inflammation, and endomyocardial fibrosis) can be produced merely by varying the types of steroids and electrolytes used, or the length of treatment. It was especially puzzling how potassium and magnesium could offer protection against so many cardiac lesions differing from one another in their morphological structure and the method of their production. The basic facts have since been confirmed in many laboratories, and, although their interpretation is still very difficult, several contributors to this monograph begin to show the direction that future research must take. It appears that the heart is capable of responding only with a limited number of reactions to the innumerable agents and combinations of agents that can act upon it. There must be a limited number of final common pathways of response. The morphologists look for them in cell membranes, structurally identifiable subcellular particles, or the “transit zone” of Hauss; the biochemist thinks of them primarily in terms of enzyme systems related to the production and utilization of energy. Undoubtedly, it is along some of these lines that a deeper understanding of the metabolic cardiopathies will come. Perhaps the best way to illustrate the limited response of the heart to various stress factors would be to present a brief outline of the concept of “pluricausal diseases,” which acted as our guide in this work, and a concise summary of the procedures developed for the production and prevention of various experimental cardiopathies.

Digitoxin Poisoning: Prevention by Spironolactone

Abstract: Spironolactone (Aldactone®) protects the rat against the production of myocardial necroses and other manifestations of digitoxin poisoning.

Renin-Aldosterone System in Parkinson's Disease

Abstract: Low blood pressure is frequent in the akinetic form of Parkinson's disease. A low renin activity in plasma as well as a low rate of aldosterone secretion is demonstrated in these patients. Renin activity in the plasma is further decreased by treatment with L-dihy-droxyphenylalanine, thus partially accouinting for the hypotensive episodes seen with this form of therapy.

Increased hepatic microsomal activity induced by spironolactone and other steroids.

Abstract: SummaryIn the rat, pretreatment with spironolactone, norbolethone, or ethylestrenol increased the oxidation of pentobarbital by liver microsomes, enhanced its disappearance from blood and proportionally decreased the depth of anesthesia.The authors wish to thank Miss Angelika Behrendt and Miss Celine Wandowska for technical assistance.

The fine structure of proliferating cells in preneoplastic rat livers during azo-dye carcinogenesis

Abstract: The continuous feeding of the carcinogenic aminoazo dye DAB to rats produces hyperbasophilic foci in the preneoplastic livers. After injections of thymidine-3H into the rats, such foci were isolated from the livers and studied by radioautography with the phase-contrast and electron microscopes. In these foci, the only cells found to be proliferating, as determined by the uptake of thymidine-3H into their nuclei, were a poorly differentiated type; well differentiated hepatocytes in the same regions were not labeled with the isotope. The labeled cells had an irregular cell outline and a high nucleocytoplasmic ratio; the cytoplasm had almost completely lost the specialized elements characteristic of hepatocytes; the irregular nuclei with prominent nucleoli, the altered mitochondria, and the increased free ribosomes noted in these cells are features which are characteristic of neoplastic cells induced by DAB. Thus, it seems likely that the hyperbasophilic foci represent the sites of extensive dedifferentiation of hepatocytes followed by rapid cellular proliferation, leading to neoplastic growth.

Fate of angiotensin I and II in the human pulmonary circulation

Abstract: The systemic pressure response technic was applied in 4 patients undergoing diagnostic catheterization. Injections were made alternately into the pulmonary artery and the ascending aorta and the systemic arterial pressor responses to each of these two routes of administration were compared. In 2 subjects, the pressor potency of angiotensin II given by way of the pulmonary artery was identical to that resulting from aortic injections, thus indicating the absence of pulmonary extraction of the octapeptide. In 2 other patients, angiotensin I was twice as potent by the pulmonary than by the aortic route; this could have resulted only from the marked conversion of the inactive decapeptide under the influence of pulmonary converting-enzyme activity. These data provide the clinical confirmation of previous animal observations pointing to the important role played by the lungs in the renin-angiotensin system. Application of the systemic pressure response technic has proved to be easy and safe during cardiac catheterization in man, and it can now be used to study the fate of vasoactive drugs or hormones in the pulmonary circulation.

Nutrition of plant‐sucking insects on chemically defined diets

Abstract: With the advent of suitable techniques for rearing plant-sucking insects, especially aphids, on chemically defined diets, knowledge of their nutrition has evolved considerably over the past 7 years. Thus, contrary to some earlier beliefs, the nutritional requirements of plant-sucking insects have been found to be, with minor exceptions, generally similar to those of other insects, and it is now possible to sustain aphid colonies on artificial diets for two or more generations, and in some cases, for an almost indefinite period of time. A discussion is presented on the comparative requirements of aphids and other Hemiptera for the main classes of nutrients and for individual compounds, both on a qualitative and quantitative basis, and on the relative importance of symbiotes in the nutrition and metabolism of these insects. Some nutritional and related factors that may influence feeding behaviour will be examined, such as the influence of the pH of the medium, the light, the quality of the diet and the concentration of certain nutrients on feeding preferences by aphids. Correlations will be attempted on the significance of these findings in relation to parasite-hostplant relationships. The main subject of the entire paper will be centered on the nutrition of about half a dozen species of aphids, but some examples will be given using other plant-sucking insects. RESUME LA NUTRITION DES INSECTES SUCEURS-PHYTOPHAGES SUR DES REGIMES DE COMPOSITION CHIMIQUE DEFINIE Les besoins nutritifs des insectes suceurs de seve, et tout particulierement des aphides, ont ete etudies a l'aide de regimes de composition chimique connue. Ces besoins se sont averes comparables a ceux des insectes en general, et on a pu jusqu'a present maintenir indefiniment des cultures d'au moins deux especes d'aphides sur de tels regimes. Il semble que ces insectes soient parmi les premiers Metazoaires a etre gardes vivants indefiniment sur des regimes chimiques definis. Les composes nutritifs essentiels aux aphides comprennent des acides amines, des vitamines hydrosolubles, dont l'acide ascorbique, des sels mineraux, et du sucrose. Dans certains cas, les microorganismes symbiotiques procurent a leurs hotes aphidiens quelques substances nutritives, dont des acides amines, des vitamines et du sterol. De plus, les proprietes phagostimulantes du sucrose et de certains composes amines ont ete demontrees experimentalement, de meme que l'influence du pH et de la qualite de la lumiere sur la prise de nourriture. Les resultats des tests de choix multiples, dans lesquels differents regimes nutritifs etaient accessibles aux aphidiens, ont demontre clairement que ces insectes peuvent choisir entre les regimes et preferer ceux qui sont de valeur nutritive superieure, c'est-a-dire ceux sur lesquels leur croissance, leur reproduction et leur survivance sont maximales. Ces resultats confirment l'hypothese par laquelle, chez les insectes, le choix d'un aliment peut etre influence considerablement par sa valeur nutritive. Il apparait evident que dans les conditions naturelles, le choix de la plante-hote, et, plus particulierement, le choix de l'endroit precis de la plante pour la prise de nourriture, et eventuellement, la pullulation de l'insecte, seront influences, entre autres, par le metabolisme et les qualites nutritives de l'hote. Finalement, il semble que des differences qualitatives et quantitatives observees entre les besoins nutritifs des differents insectes suceurs de seve se reveleront etre en relation de plus en plus etroite avec leurs habitudes oligophages ou polyphages, et avec le pouvoir de synthese de leurs symbiotes.

Relationship of piaget measures to standard intelligence and motor scales

Abstract: A 3-yr. longitudinal study of standard IQ tests and Piaget developmental scales for children ages 5 to 8, shows a high relationship (.52, .57, .62) between the tests despite theoretical differences...

Endothelial microvilli in the vessels of the rat gasserian ganglion and testis.

Abstract: In the Gasserian ganglion and testis of the rat the endothelium of the small blood vessels has a singular appearance due to the presence of a high number of microvillous processes. These arise from the luminal surface, either individually, or in small groups. The significance of this structure is not known. It is pointed out that these vessels are particularly sensitive to cadmium intoxication.

An Approximation to the Wilcoxon-Mann-Whitney Distribution

Abstract: An approximation, based on the sum of independent uniform random variables, to the Wilcoxon-Mann-Whitney null-distribution, is proposed. Numerical comparisons with the normal approximation show that this uniform approximation is appreciably more accurate even when the smaller sample size is large. A table of percentiles of the distributions of the sum of independent uniform random variables is given for the uniform approximation. An extension of existing tables of percentiles of the exact distribution is also given.

Prevention by spironolactone of 7,12-dimethylbenz(a)anthracene-induced adrenal necrosis.

Abstract: SummaryAdministration of spironolactone protects the rat against 7,12-dimethylbenz (a) anthracene-induced adrenal necrosis.

Carbohydrate intolerance in gout.

Abstract: A three-hour oral glucose tolerance test (OGTT) was carried out in thirty consecutive cases of gouty arthritis. All subjects were male members of the Canadian Armed Forces. According to the most widely used criteria, the OGTT curve was “borderline” in two-thirds of the subjects, and strongly suggestive of diabetes in one-third to one-half. Depending on the criteria used for diagnosis, from 7 to 55 per cent of the subjects were “established” diabetics. In none of the 30 subjects had diabetes been previously suspected. It is apparent that the variability of currently accepted criteria for the interpretation of the OGTT, especialy in the range where a distinction is established between those individuals with a diabetic tendency and those without, greatly affects the significance of studies such as this one. It is difficult, however, not to conclude that in the present group, carbohydrate intolerance of the type found in diabetes mellitus was much more frequent than could be explained by chance alone.

The action in vivo of a structural analogue of GABA: hydrazinopropionic acid.

Abstract: — The action of hydrazinopropionic acid in vivo on the metabolism of amino acids in the CNS of mice was studied over a period of 24 hr. At 82 μmoles/kg, a transient fourfold rise in the levels of tyrosine occurred followed by a more moderate and prolonged increase in the levels of GABA. When the dose of hydrazinopropionate was raised to 123 μmoles/kg, the changes in the levels of tyrosine were identical with those at the lower dose, while levels of GABA rose further before reaching a steady state. Levels of glutamate decreased concomitantly. In addition, the concentrations of alanine, β-aminoisobutyric acid and an unknown compound tended to rise. A doubling of the dose to 246 μmoles/kg enhanced the effects obtained with the lower doses but did not produce any new changes in the patterns of amino acids of the CNS. The elevation in the concentrations of alanine paralleled changes in the levels of tyrosine. The changes in the concentrations of the unknown compound, tentatively identified as α-aminoadipate, and of β-aminoisobutyric acid resembled those of GABA. The results are interpreted to indicate an inhibition by hydrazinopropionic acid of tyrosine aminotransferase and aminobutyrate aminotransferase.