De la réaction mitotique de l'épiderme de la tétine de cobaye à la suite d'applications répétées de diverses substances

Summary (1) The majority of substances tested produced a weaker mitotic reaction of the epidermis of the guinea pig nipple after 3 applications (24 h intervals) of the same substance than after a single application.(2) This decrease in the ability of the epidermic cells to be divided has to be attributed, it seems, to a habit-forming processus and not to an exhaustion of the cells; indeed after two applications of geraniol, the application of a substance of different nature, Hormoestrol, produced in the nipple epidermis a mitotic flare up as intense as that obtained in the epidermis of a nipple not previously treated.(3) Aldehyde C₉ alone, among the substances tested, does not produce a decrease of epidermic mitoses after three applications but induces cellular alterations.     

Effet inhibiteur de la tétrabénazine sur l'influence corticosurrénalienne de la réserpine

Summary Reserpine provokes an intense and long-lasting (more than 20 h) stimulation of the adrenocortical activity of the rat. Tetrabenazin (50 mg/kg) also produces an adrenocortical stimulation which is, however, of a much shorter duration. The injection of tetrabenazin 1 h before the injection of reserpine (5 mg/kg) prevents the prolonged stimulating effect of reserpine on the adrenal cortex. This effect can be compared with the blocking effect of tetrabenazin, a short-acting central depressant with monoamine-liberator properties, against the prolonged central sedative influence of reserpine.     

La spécificité de la réaction de Feulgen pour la détection de l'acide thymonucléique

Summary A number of experiments all led to the conclusion that the Feulgen reaction is a valuable test for thein situ localization of thymonucleic acid: there is thus no serious reason to doubt that this acid is a constituent of chromatin and chromosomes.     

Substances régulatrices de la croissance végétale

Zusammenfassung Durch Einwirkung von Simazin wird bei Elodea die Photosynthese gehemmt, der Sauerstoffverbrauch durch Atmung erhöht und keine Zerstörung der Zellbestandteile beobachtet. In Gegenwart von Simazin bleiben die Deshydrasesysteme der Zelle aktiv.

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5^e communication (voir les travaux précédents deA. Gast etB. Exer).     

Importance des modifications de la glycémie dans la régulation de la vitesse d'absorption de solutions de glucose de différentes concentrations chez l'animal intact

Summary In intact guinea-pigs fed with glucose solutions of different concentrations, the main limiting factor of absorption is not the gastric emptying but the hyperglycaemia.     

Effet de l'hypothermie modérée sur le comportement maternel de la rate

Summary The maternal behaviour in the female white rat was ascertained by the method of spontaneous reactions to several stimuli.The observed rats were divided into two groups, and each of them was refrigerated once a day, by the method of detension, from the fourth to the seventh day after parturition, the body temperature attained being, on an average, 30°C. Females of the first group were refrigerated in recipients of the capacity of 2 1, and females of the second group in recipients of the capacity of 5 1.Disturbances of maternal behaviour were much more pronounced in the females refrigerated in recipients of the greater capacity than of those refrigerated in smaller recipients.     

Recherches sur le mécanisme de la rétraction du caillot et de la métamorphose visqueuse des plaquettes

Summary The concept, that viscous metamorphosis of platelets and clot retraction is initiated by thrombin and a dialyzable factor was confirmed. Under certain circumstances glucose acts as dialyzable factor. Clot retraction seems to depend upon the catabolism of glucose.     

Action répressive de l'oxygène sur la biosynthèse de la fumarique-réductase d'Aerobacter aerogenes

Summary The cells obtained from anaerobic cultures ofA. aerogenes contain both a hydrogenase and a fumaric reductase, but lack one or several electron transporters necessary for the coupling of the two enzymes. It is possible to measure the fumaric reductase activity of the extracts in the presence of hydrogen, hydrogenase and benzyl viologen, using the Warburg manometric technique. In anaerobic cultures the reductase is an inducible enzyme. In aerobic cultures its formation is strongly repressed by atmospheric oxygen.     

Influence de laβ-mercaptoéthylamine sur la réponse de l'intestin grêle du rat à une irradiation rœntgénienne localisée

Summary Intra-peritoneal injections of 15 mg of B-mercaptoethylamine in rats, with an average weight of 200 g, protect the small intestine against a local irradiation of 500 r on the antero-upper portion of the abdomen.This protection is proved mainly, as compared with the control, by a smaller decrease of cells still in mitosis after 12 and 24 hours and of the migrant cells in resting stage, by a greater precocity and higher quantitative value of the post-radiation normal and subnormal mitotic processes, and by variations in the mitotic formula (namely, in protected animals, a relatively high increase in the amount of metaphases).These experiments seem to prove a certain local and immediate action of the radio-protector, whose effects are not solely limited to the preparation of the generating system of the intestine for the later complete repair of the digestive epithelium.

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(Travail du Centre anticancéreux de l'Université de Liège et du Centre national belge pour l'étude de la croissance normale et pathologique).     

Existence de sels biliaires et de cérébrosides associés à des protéines chezMoniezia expansa

Sans résumé     

Activation de la phosphatase acide par l'acide β-indolylacétique et ses répercussions sur la phosphorolyse de l'amidon

Summary IAA-induced activation of purified acid phosphatase is reported and shown to determine an acceleration of phosphorolysis of starch.     

Activation concomitante par l'hétéroauxine de la résorption du corps paranucléaire ribonucléique et de la germination des zygotes chezAllomyces

Summary Heteroauxin (optimal concentration 10^–5) activates the germination of the zygotes and the dissolution of their RNA nuclear cap inAllomyces javanicus.Alkaline phosphatase has been located cytochemically in the cytoplasm surrounding the RNA nuclear cap.These new observations lead the author to postulate a relationship between the stimulating action of heteroauxin, activation of the phosphatases and awakening of the RNA-protein synthesis dynamic system during the germination of the zygotes inAllomyces.     

Influence de l'anaérobiose et de différentes tensions d'oxygène sur la libération d'histamine dans la réaction anaphylactiquein vitro

Summary The influence of anaerobiose and of varied oxygen tensions upon respiration and histamine release during anaphylactic reaction in guineapig lung slicesin vitro was studied.No histamine was liberated in the absence of oxygen. With increasing oxygen tensions, increasing histamine quantities were released; these quantities reached the control values when the atmosphere contained 10% oxygen.These results indicate that the mechanism of histamine release in the anaphylactic reaction is linked with the aerobic metabolism of the cell.

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Boursicrs du Consclho Nacional de Pesquisas.     

Sur le rôle de la sélection sexuellen dans l'évolution

Zusammenfassung Von Darwins Theorie der geschlechtlichen Zuchtwahl ausgehend werden einige Resultate experimenteller Forschung dargestellt, die auf neue Aspekte dieser Frage hinweisen. Es wird der qualitative Unterschied zwischen interspezifischer und intraspezifischer geschlechtlicher Zuchtwahl aufgezeigt. Die erstere hindert den Genaustausch zwischen den Arten, die letztere dagegen führt zu einem optimalen Genaustausch innerhalb einer Art. Es werden die Rolle der Weibchen und Männchen, der selektive Wert des Wildtypus verglichen mit Mutanten und die genetische Basis der Aktivität der Männchen diskutiert.     

Activité de la glycéraldéhyde-3-phosphate déshydrogénase dans la rétine du lapin et dans la rétinite pigmentaire expérimentale provoquée par le monoiodacétate. Etude histo-chimique

Summary The author established that, at the moment of the extinction of the electroretinographic response after i.v. injection of iodacetate, the glyceraldehydephosphate dehydrogenase activity is suppressed in the retina of the rabbit.     

Étude quantitative de la régénération caudale,avec ou sans moelle épinière,chez la larve de Salamandre

Summary Tail regeneration in the absence of spinal cord was studied quantitatively in larval salamanders. Growth parameters were calculated according to the function =1/ny _i /x _i (Rao).The regeneration rate of despinalized tails was found to be approximatively half the normal rate in both the length and volume.The real nature of despinalized tail regenerates is discussed and two hypotheses are proposed for their explanation.

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Travail exécuté grâce une subvention de la «DonationGeorges etAntoine Claraz, instituta et curataJohannis Schinz professoris auspiciis».     

Microméthode potentiométrique pour la détermination de la cholinestérase

Sans résumé