Un cas d'interprétation difficile: La nature du sel principal de l'os étudiée par la diffraction des rayons X

Summary The application of physical methods to the resolution of problems concerning biology might sometimes lead to misinterpretations. We consider, for instance, the successive stages of the study of the principal bone salt components by the X-ray diffraction method.     

Recalcificationin vitro de l'os compact décalcifié

Summary We report the possibility of recalcifying decalcified sections of adult compact bone. Recalcification occurs mainly in those osteons which had a low calcium contentin vivo.     

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.     

Sur la nature de l'estérase contenue dans le venin de cobra

Zusammenfassung Mit Hilfe derWarburg-Methode wird die Esterasewirkung von Kobragift geprüft. Das Ferment wirkt nicht nur auf Acetylcholin, sondern auch auf verschiedene andere Ester mit kleinerem Molekulargewicht, die die Acetylgruppe enthalten. Es ist demnach nicht als Cholinesterase, sondern als Acetylase zu bezeichnen. Myristicylcholin beeinflußt die Cholinesterase im Blutserum des Hundes nicht, hemmt dagegen die Acetylase im Kobragift.     

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.     

Le rôle du scientifique dans la conservation de la nature

Summary The concept of nature conservation has greatly varied in recent years. Instead of forbidding any human interference with nature the modern conservationnists think that man must control the natural balance in the protected areas through appropriate measures.This action must be under the permanent control of ecologists, who have the task of determining, among many other data, the carrying capacity of the area, the evolution of habitats under physical and biological influences, the structure of animal populations and the rate of reproduction.In the case of large animals, this new concept leads to substituting game management for static protection. Thus conservation of natural resources will need more and more cooperation from scientists, especially in the field of ecology and population studies.     

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 détermination expérimentale de la masse des mésotons par les méthodes d'ionisation

Sans résumé     

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.     

Microméthode potentiométrique pour la détermination de la cholinestérase

Summary A simple very sensitive and usefull method is described for the potentiometric micro-determination of the cholinesterase of blood serum, globules and tissues, using an ordinary potentiometer and an antimonium electrode. This method makes it possible to determine the cholinesterase in solutions of acetylcholine down to 3 mg %.     

Microméthode potentiométrique pour la détermination de la cholinestérase

Sans résumé     

Pharmacodynamie de la circulation cérébrale

Sans résuméRelation présentée au XXI^e Congrès International des Sciences Physiologiques, Buenos Aires, 9–15 août 1959.     

Les effets de l'autotransplantation préportale de la thyroïde chez la Rate

Zusammenfassung 90 Tage nach einer in der Gegend der Pfortader erfolgten Autotransplantation der Schilddrüse bei weiblichen Albinoratten zeigt die histologische Untersuchung der Transplantate alle Zeichen einer gesteigerten Tätigkeit. Dem entgegengesetzt befinden sich Nebenniere, Leber und Hypophysis in dem als Folge der Schilddrüsenextirpation beschriebenen Zustand. Dieser scheinbare Widerspruch stützt die Annahme einer Inaktivierung des Schilddrüsenhormons durch die Leber.     

Essais de solubilisation et de détoxification de la Tyrothricine

Summary As Tyrothricin —Dubos's discovery of the antibiotic agent extracted from cultures ofB. brevis — does not give true aqueous solutions and retains, in the colloïdal state of the usually employed solutions, toxic properties for polymorphonuclear blood cells, we have attempted to effect the solubilization and detoxification of this compound. Treatment with formalin in given proportions results in making it water-soluble. The action of the formalin-treated compound on blood cells suspended in Ringer's solution seems to show a loss of toxicity. Subcutaneous and intramuscular injections in mice do not give visible general toxic effects, and the experiments incite to further investigations in this direction.     

Etude photophysique de la ptérobiline

Summary The first results of a photophysical study on pterobilin (biliverdin IX , a Lepidopter blue bile pigment) are presented. From the absorption and fluorescence spectra, it is deduced that the low yield of fluorescence indicates a desactivation of the excited singlet state occurring mainly by a non-radiative process. Analyses of the chemical compounds formed after irradiation of pterobilin in methanol show that it is rearranged into a series of new blue pigments among which phorcabilin and sarpedobilin (the two neobiliverdins IX isolated from Lepidopters) have been identified.

---

---

Remerciements. Nous remercions le ProfesseurJ. Bergerard pour son intérêt. Ces recherches ont été réalisées dans le cadre de l'ATP CNRS No. 4699-10.     

Le Palais de la Découverte

Sans résumé     

Aspects biochimiques de la Régénération

Summary A survey of the biochemistry of regenerating animals has been made: after a critical discussion ofChild's metabolic gradients theory, the relative importance of respiration rate, carbohydrates, proteins and nucleic acids metabolism are stressed. The similarities between biochemical processes in the embryo and the regenerating organism are pointed out.

---

---

Une grande partie de cet article est la reproduction d'un chapitre de notre livre « Embryologie chimique » (Masson, Paris, etDesoer, Liége); nous tenons à remercier les éditeurs de l'ouvrage qui ont bien voulu marquer leur accord. On y trouvera une bibliographie étendue sur les modifications chimiques dont l'organisme en régénération est le siège.     

Propriétés phytobiologiques de la sérotonine

Summary The serotonin (5-hydroxytryptamin) which shows a slight influence upon the growth of plant tissues, acts upon water uptake by regulating cellular permeability (latter is activated in the case of K⁺).