Biosynthèse des hormones stéroïdes

Summary The different pathways of biosynthesis are described, by which steroid hormones are producedin vivo in the gonads, the adrenal cortex and the placenta, orin vitro by corresponding tissue preparations. First of all a short outline of the origin of cholesterol from acetyl coenzyme A through the biological isoprene unit, the pyrophosphate of ³-iso-pentenol, through squalene, lanosterol and zymosterol is given. Partial side-chain degradation of cholesterol, where ACTH plays an important role, leads to pregnenolone and further to progesterone.The latter compounds are the starting material for the other steroid hormones. On the one hand, they are converted in the gonads and adrenals into 17-hydroxy derivatives, in which the side chain is completely removed by enzymes of the said and also of non-endocrine tissues, to form the androgens. Furthermore the adrenals produce their own typical androgens. After hydroxylation of the angular 19-methyl group, androgens are aromatised to estrogens.On the other hand, the adrenal converts progesterone by hydroxylation in 21- and, depending on the case, also in 11- and/or 17-position into the classical adrenocortical hormones. The special feature of an 18-hydroxylation and -dehydrogenation forms part of the biogenesis of aldosterone; a new example is given for the methods used towards its elucidation, consisting in the biosynthetic conversion of progesterone into two virtual intermediates, 18-oxo-progesterone and 21-desoxyaldosterone, which already contain the 18-aldehyde group, characteristic for aldosterone.The regulation of the biogenesis of the different hormones is mentioned and compounds are discussed which block one or other of the biosynthetic steps.

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D'après une conférence faite aux VIes Journées biochimiques latines, Genève (Suisse), 25 mai 1961.

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Publication No. 179Über Steroide. Communication No. 178 voirK. Heusler, P. Wieland etA. Wettstein, Helv. chim. Acta, sous presse.     

Sur la caractérisation de dérivés guanidiques d'origine biologique par électrophorèse et chromatographie sur papier (chromatoélectrophorèse)

Summary Paper chromatography has been used in conjonction with electrophoresis in a perpendicular direction (chromatoelectrophoresis), in order to characterize various guanidoderivatives of biological interest and also citrulline. The isolation of definite spots can be obtained with a satisfactory selectivity by this procedure, at a higher speed than by bidimensional chromatography; and the use of a few coloured reactions (ninhydrine,Sakaguchi, diacetyle--naphtol andp-dimethylaminobenzaldehyde) on the same electrochromatogram has been successfully practised in this field.     

L'électrophorèse sur papier des protéines hydrosolubles du cristallin

Summary By using paper electrophoresis, the authors succeeded in demonstrating different protein fractions in human and animal lenses.Qualitative and quantitative differences were noted in different animals, between the cortical and the nuclear areas of the lens, and also according to age.

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Chargé de Recherches du Fonds national de la Recherche scientifique.     

Séparation chromatographique de sucres méthylés isomères

Summary The qualitative and quantitative analysis of synthetic mixtures of non-isomeric and isomeric methylated glucoses, as present in the hydrolysate of methylated glucopolysaccharides, has been achieved by hydrogenation of the methylated sugars to the corresponding methylated hexitols, esterification withp-azobenzoylchlorid, and chromatographic analysis on activated alumina.     

Préparation des sous-unités de la dopamineβ hydroxylase humaine et des anticorps anti-sous-unités

Summary The present study deals with the dissociation of human dopamine hydroxylase (DBH) in subunits with a mol. wt of 79,500, and the preparation of specific antibodies in rabbits. No cross-reactivity was observed between human DBH and antibodies against human DBH subunits.

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Nous remercions Madame M. Le Maout pour son excellente aide technique.

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Ce travail a bénéficié de l'aide de l'INSERM (contrat no 75.4.161.2).     

Recherches sur la fraction Y des protéines de muscles de Lapin

Summary The proteinic material corresponding toDubuisson's electrophoretic gradient has been prepared by a new method. This fraction migrates as a single peak in the U-tube, but is heterogeneous in the ultra-centrifugation.     

Age des halos pléochroïques de la granodiorite de Lausitz

Summary By a quantitative study of pleochroic haloes in biotite, the haloe age of the Lausitz granodiorite, in comparison with the granite age of the Elba Isle, was estimated to 280±150 M.Y. The granodiorite is either caledonian or hercynian.

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Attachée à l'Institut Interuniversitaire des Sciences Nucléaires.     

Dosage de la procaïnestérase sérique par spectrophotométrie différentielle

Summary A method is proposed for dosage of serum procainesterase by differential spectrophotometry, based on the decrease of the optical density at 295 mµ in the course of the hydrolysis.     

Modifications de l'excitabilité des centres vasopresseurs hypothalamiques par des injections locales de catécholamines

Summary The blood pressure is not disturbed by a local injection of norepinephrine into the hypothalamus, but the excitability of vasopressor centres is affected. Often, the excitability of these centres is decreased; sometimes, it is increased, and, more rarely, it is first potentiated and then inhibited. Epinephrine has the same action, but dopamine is less potent; isoprenaline produces both facilitation and inhibition of these centres, but the facilitating effect is more frequent than with norepinephrine.     

Mesure des âges géologiques par les halos pléochroïques

Summary In this preliminary work, the possibility of dating crystalline rocks by pleochroic haloes has been studied.Halo-microphotometry has been combined with measurement of the alpha-activity of the inclusions by the photographic method.Standard thin sections of well dated granites have been used for calibration purposes. The reciprocity law is shown to be valid within the limit of error. The resolving power of this method depends essentially on the age ratio. Tertiary and primary rocks are easily separated.     

Action des enzymes sur la gonadotropine urinaire de ménopause

Summary The action of various proteolytic and glucidolytic enzymes on the biological potency of Human Menopausal Gonadotropin was studied. Trypsin, chymotrypsin, papaïn and glucosidase attack the gonadotropin only after 6 h of digestion. Carboxypeptidase and RDE produce a rapid inactivation.     

Etude de la glucose-6-phosphatase dans la membrane chorioallantoïdienne traitée par des microsomes du foie

Summary In order to test the possibility for microsomes to multiply like viruses, microsomes of chick liver were inoculated on chorioallantoïc membranes. The glucose-6-phosphatase activity, an enzyme located in the liver microsomes, was determined in the treated membranes. The activity decreased during the first 24 h after inoculation. It reached, after 48 h, from two to six times the value attained after 24 h.A suspension of heated granules, or of heatedTétrahymèna géléii, though producing the same lesions of the membrane, did not increase the phosphatase activity of the microsome fraction after 48 h.The present results are compatible with the idea that liver microsomes multiply by autoduplication.     

Age des halos pléochroïques de quelques granites tertiaires de la Toscane

Riassunto Sono stati studiati gli aloni dei graniti delle isole di Montecristo e del Giglio (arcipelago toscano) e del continente (Gavorrano).Tale studio ha permesso di dimostrare che il loro consolidamento è avvenuto in momenti diversi la cui successione ripete quella dei corrugamenti appenninici. Le età di tali graniti, comparate a quella dell'Elba (Monte Capanne), sono nel seguente ordine:Elba = Montecristo > Giglio > Gavorrano.I singoli stadi sono largamente spaziati nel tempo e gli intervalli sono risultati dell'ordine di circa dieci millioni di anni.

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Attachée à l'Institut Interuniversitaire des Sciences Nucléaires.

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Comitato Nazionale per le Ricerche Nucleari.     

Etude histochimique de l'action des rayons X sur les cholinestérases

Summary Using a histochemical method, we have observed the cholinesterase activity in mice after X irradiation. Both types of cholinesterases were examined: AChE (specific ChE) of megacaryocytes of spleen and bone marrow, and AChE of motor endplates; and non-specific ChE of liver, pancreas and prostate. There is no inactivation of AChE even after 5000 r. ChE is also very resistant: activity is slowed down only 12 h or even a few days following irradiation and the inactivation remains slight. We suppose that the great alterations in cellular permeability caused by irradiation are not correlated with these enzymes.     

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.     

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.     

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

Sans résumé