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.     

Recherches sur la biosynthèse des caroténoïdes chez un microorganisme. Production de caroténoïdes marqués parPhycomyces blakesleeanus

Zusammenfassung Unter Verwendung eines speziellen Milieus wurde gezeigt, daß beiPhycomyces Na-Azetat die Vorstufe des -Karotins darstellt. Durch Verwendung von markiertem Azetat (¹⁴CH₃·COONa und CH₃·¹⁴COONa) wurde bewiesen, daß 25% des Gesamtkohlenstoffes des Karotins aus der CH₃-Gruppe und 50% aus der COOH-Gruppe stammen.     

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.     

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.     

Sur l'action des esters amides polyphosphoriques de l'aneurine sur la glycolyse par le sang lavé

Summary The polyphosphoric amidic esters of thiamine and the sodium polyphosphates markedly influence the formation of lactic acid in the fermentatory processus established by employing washed human blood. Under the same conditions cocarboxylase does not act.     

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).     

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.     

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.     

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.     

Influence de l'énervation sur la composition des extraits protidiques des muscles striés

Summary The denervation atrophy (16 to 48 days duration) of striated rabbit muscles shows, according to electrophoretic investigations of crude protein extracts, a characteristic complex alteration in the protein composition of these muscles. Beside of the decrease in the myosin content, as previously described by others, a progressive decrease of the myogens and rise of the myoalbumin are noticeable. These quantitative changes, observable in tissue extracts, are almost surely related to corresponding quantitative changes occurring in the tissue in the cases of the myogens and myoalbumin. As far the myosins are concerned, the fact does not appear so clearly because the observed decrease could be related also to changes either in the conditions of extractibility or in these of solubility.     

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.     

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.     

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.