Contribution à l'étude d'une propriété répétitive du cerveau

Summary While pursuing the study of cortical functioning by the EEG. and after-image methods, we have come to believe that every stimulation evokes in the corresponding area of the cortex not only a simultaneous excitation but also acontinued action, i.e. after stimulation, several successive excitations of progressively diminishing intensity appear in the same area of the cortex.We have investigated the continued groups appearing on corticographical tracings taken from different cortical areas of the experimental animal (the rabbit) after various forms of stimulation (auditory, electrical, and visual). By comparing them with the after-images seen by human subjects in EEG. experiments, we have been led to identify the two phenomena.In order to carry this study further, we have undertaken two series of corticographical experiments, recording tracings takensimultaneously from the parietal and striate areas of the rabbit. The first series was intended to study the effects on the tracings of visual stimuli. The second was concerned with the effects on the same tracings of weak electrical stimuli.

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Nous avons consacré à cette propriété répétitive du cerveau une note parue dans les Comptesrendus de l'Académie des Sciences, Juillet 1955, Paris — dont le présent article constitue le développement.     

Activation thyréotrope des urines du cobaye par la rupture de l'équilibre thymus-thyroïde-gonades

Summary (1) It had been stated previously that in guinea-pigs the rupture of the thymus-thyroid-gonad balance resulted in an increased thyrotropic activity of the anterior pituitary.(2) An attempt is made to verify this assertion. It was to be expected that in thymi-thyreoprive castrated guinea-pigs (which do not secrete any thyrotropic factor) injections of one or several hormones of the thymusthyroid-gonad group in an unbalanced relation might determine an increased thyrotropic activity of the urine.(3) Experimental results have confirmed this supposition.     

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.     

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.     

Sur l'apparition d'organes variés dans l'ectoblaste, à la suite de la centrifugation de la blastula et de la gastrula chez les Amphibiens

Summary The centrifugation of the Amphibia blastula or gastrula produces in the ectoblastic area the appearance of complexes of ecto- and mesoblastic organs. Experiments of explantations and cultivationin vitro and also of grafts on a normal embryo demonstrate that those very abnormal secundary embryos are formed without any intervention of the normal organizer. The ectoblastic cells that undergo this increase of morphogenetic potential are characterized by a great concentration of ribonucleic acid in their cytoplasm (this part of work in collaboration withJ. Brachet). Those secundary embryos vary greatly in their frequence, their nature, and their location, depending on the stage in which the centrifugation was done. It is supposed that the nature of the organs formed is dependent on the degree of potency attained by the ectoblast at the time when the reaction arises that is produced by the cellular trauma.     

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.     

Principes généraux de la magnétochimie,ses applications à l'étude des structures

Summary This article presents the general principles of magnetochemistry, its methods and the results to which it leads. Firstly, the definitions of magnetic units of isotropic substances are defined. Then the main apparatus for measuring magnetic susceptibilities is indicated.The notion of a magneto-chemical system is developed and its use in the study of molecular structure is shown. Finally, the author shows how magnetochemistry has been used to study the electronic delocalisation in aromatic molecules, and the concomitance existing between this delocalization and the biological properties of certain substances, such as their mitotic and carcinogenic activities.     

Injection à des souris nouveau-nées de cellules hématopoiétïques homologues de donneurs adultes ou embryonnaires. Fréquence de la greffe érythroblastique et de la «Runt Disease»

Summary The endoveinous injection to newborn mice of homologous hemafopoietic cells either adult or embryonnic, may result in a lasting and functional graft.The former statement can be demonstrated by use of starch gel electrophoresis which shows the specific hemoglobin of the donors.In both uses this graft can induce a runt disease.     

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.     

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).     

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.     

Etat chimique des atomes issus de U238 au cours de la réaction (η, γ) et de la désintégration naturelleα

Zusammenfassung Eine Lösung von Uranylsalizylaldehyd-o-phenylendiimin in Pyridin wurde einer Neutronenbestrahlung unterworfen und das Verhalten der durch Szilardeffekt entstandenen radioaktiven Atome in einem elektrischen Feld untersucht. Es wurde folgendes festgestellt: a) die aus U durch natürlichen -Zerfall entstandenen UX₁-Atome sind geladen und werden an der Kathode gesammelt; b) die durch Neutroneneinfang gebildeten U²³⁹-Atome liegen neutral in der Lösung als Oxyd vor und werden nicht an den Elektroden gesammelt.     

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.     

Quelques problèmes physiologiques posés par leSalmo Salar. Intérêt de l'étude de lasmoltification type de préparation au comportement migratoire

Summary The author considers some physiological problems raised by particularities of the physiological cycle ofSalmo salar L. about which he and his fellow-workers have produced new data (especially those brought out by the physiological, normal fasting so particular to the adultS: The synchonic fasting of Mislin).He insists on the importance, for studies on the physiological mechanism of migrations and from the methodological point of view, of the following feature of the young Salmon in fresh water: a transformation which, in the population studied (S. s. of Adour waters), is so characteristic of and tightly bound to the preparation to catadromic migration that it marks the subjects ready for migration and makes it possible to particularise the new physiological conditions accompanying the phenomenon of migratory instinct (activation of thyroid and interrenal function, of some pituitary neurosecretions and secretions, metabolic changes ). By studying simultaneously: smoltified but not yet migrant fishes, smolts during migration, and a salmonid fish subjected to a current in conditions simulating those of migrating smolts, it is now possible to begin to distinguish the physiological features bound to the preparation for migration, from those resulting from migratory activity.     

L'acide thymonucléique polymérisé, principe paraissant susceptible de déterminer la spécificité sérologique et l'équipement enzymatique des bactéries. Signification pour la biochimie de l'hérédité

Summary Interactions between two types of bacteria can produce either inhibition of the growth of one of these bacteria or transformation of their biochemical or antigenic properties. Authors have shown and studied one case of induction of a new serological specificity and a new enzymic equipment in aBacterium coli. This induction was produced through a substance liberated, during autolysis, by an otherBacterium coli. Active principle is a thymonucleic acid which, maybe, results from a solubilisation of chromosomes of the inductor bacteria. Hypothesis appears likely.