Demonstration of two ATPases in human erythrocyte membranes

Zusammenfassung Menschliche Erythrozytenmembranen enthalten eine NEM-sensitive und eine NEM-insensitive ATPase, die wahrscheinlich beide an Membranoberflächen lokalisiert sind.

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These studies were carried out with the generous support of the Deutsche Forschungsgemeinschaft.     

Identification of steroid hormones fromLacerta sicula testes

Riassunto Gli autori hanno analizzato gli steroidi presenti nel tessuto testicolare diLacerta sicula. Sono stati identificati i seguenti steroidi: progesterone, androstenedione, testosterone, androsterone, deidroepiandrosterone, pregnenolone, 20-idrossipregn-4-ene-3-one, estradiolo-17, estrone. Viene discusso il rapporto progesterone androstenedione testosterone, paragonandolo a quello trovato in altri vertebrati inferiori.     

Effects of EDTA on (Na+-K+) ATPase bound to human erythrocyte membranes]

Membranes preincubation with high EDTA concentration induced an alteration on (Na"-K+) ATPase kinetic behaviour. This effect can be related to a change in calcium content tightly bound to the membranes.     

Effect of alkali cations on the interaction between detergents and erythrocyte membranes

Resumen Los distintos cationes alcalinos monovalentes (145 mM) y divalentes (100 mM) modifican marcadamente el grado de hemólisis de eritrocitos humanos provocado por Triton X-100 y por desoxicolato de Na (DOC). La serie de actividad con cationes monovalentes en hemólisis por Triton es K>Rb=Cs>NaLi, y por DOC es Li>Rb=Cs>K>Na. Por el contrario, el grado de solubilización de membranas eritrocitarias producido por Triton o DOC es independiente de los distintos cationes alcalinos.     

Identification and biosynthesis of steroid hormones in the gonads ofCiona intestinalis

Riassunto Da 185 g di tessuto testicolare diCiona intestinalis sono stati estratti ed identificati i seguenti ormoni steroidi: deidroepiandrosterone, cortisone e cortisolo. Nel tessuto ovarico é presente il cortisone. Incubando il tessuto testicolare con pregnenolone-7-H³ e progester-one-4-C¹⁴ sono stati isolati i seguenti metaboliti: deidroepiandrosterone, testosterone, e desossicorticosterone. Dalle incubazioni del tessuto ovarico con gli stessi precursori sono stati isolati i seguenti metaboliti: 17-idrossipregnenolone, deidroepiandrosterone, androstenedione, testosterone, desossicorticosterone e cortisone.

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Research supported by a grant from the National Research Council of Italy.     

(Ca−Mg) ATPase activity of human erythrocyte membranes: Influence of incubation buffer

Summary Activity of the (Ca–Mg) ATPase of human red blood cell membranes is highly dependent on the specific buffer used in the ATPase assay. Activity is highest in histidine and/or imidazole buffers and is lowest in HEPES buffer.This research was supported by Public Health Service Grants AH-16436 and GM 00109-16. We wish to acknowledge the useful suggestions of Thomas R. Hinds and the excellent clerical assistance of Ms Laurie Asher.     

In vitro conversion of steroid hormones in bovine ovarian follicles

Summary In bovine ovarian follicles an in vitro conversion of androstenedione and oestrone into oestradiol-17, and of oestradiol-17 into oestrone was observed. There was no in vitro conversion of pregnenolone, progesterone, dehydroepiandrosterone and testosterone.     

The effects of two neutral polymers on the geometry and deformability of the human erythrocyte

Summary Polyvinylpyrrolidone and dextran decrease cellular deformability. Changes in volume do not wholly account for the changes which imply a stiffening of the plasma membrane. The effects differ from those induced by charged macromolecules.The work was supported by the Medical Research Council of Canada.     

The effects of two neutral polymers on the geometry and deformability of the human erythrocyte.

Polyvinylpyrrolidone and dextran decrease cellular deformability. Changes in volume do not wholly account for the changes which imply a stiffening of the plasma membrane. The effects differ from those induced by charged macromolecules.     

A dialysis rate method for the measurement of free iodothyronine and steroid hormones in blood

From the dialysis rate of a small amount of tracer hormone from a serum sample through a semipermeable membrane towards an identical serum sample, the free hormone fraction can be calculated. This method is free from a number of artefacts that may occur in equilibrium dialysis.     

Effect of cholesterol oxidation on (Na+, K+) ATPase activity of erythrocyte membranes

Summary By incubation of human erythrocyte ghosts with cholesterol oxidase (EC 1.1.3.6) part of the cholesterol of the membrane is replaced by 4-cholesten-3-one. This alteration in the sterol composition is accompanied by an inhibition of the (Na⁺, K⁺) ATPase of the erythrocyte membrane.Acknowledgments. This study was supported by the Deutsche Forschungsgemeinschaft Bonn-Bad Godesberg and the Sonderforschungsbereich 90 of the University of Heidelberg. We thank Mr.J. Schmidt and MissI. Geldmacher for skilful technical assistance.     

Insulin effect in vitro on human erythrocyte plasma membrane

Summary The effect of porcine insulin has been tested in vitro on human erythrocyte plasma membrane (Na⁺–K⁺) and Mg²⁺-ATPase activities as well as on membrane fluidity. The results indicate that the hormonal treatment significantly inhibits (Na⁺–K⁺)-ATPase activity, and at the same time decreases membrane fluidity.This investigation has been supported by Consiglio Nazionale delle Richerche, Rome, Italy.     

Comparison of preparations of erythrocyte membranes and membrane proteins by SDS-Gel electrophoresis

Résumé Quelques préparations de membranes érythrocytaires et de leurs protéines extraites en phase aqueuse ont été comparées par électrophorèse sur gel de SDS-polyacrylamide. De faibles différences seulement ont été notées d'une préparation à l'autre. Les extraits obtenus à force ionique basse ou élevée contiennent tous la même protéine de poids moléculaire élevé (spectrine) mais different quant à leur contenu en peptides de faible poids moléculaire. Les préparations obtenues à l'intérieur de chaque groupe s'avèrent fondamentalement semblables.

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We would like to thank Dr.Paul Bredderman for many discussions about gel electrophoresis. This work was supported by postdoctoral fellowship No. 34600 from the National Heart and Lung Institute, and by USPHS Grant No. AM1548-03. This paper is also based on work performed under contract with the U.S. Atomic Energy Commission at the University of Rochester Atomic Energy Project and has been assigned Report No. UR-3490-239.     

Insulin effect in vitro on human erythrocyte plasma membrane

The effect of porcine insulin has been tested in vitro on human erythrocyte plasma membrane (Na+-K+) and Mg2+-ATPase activities as well as on membrane fluidity. The results indicate that the hormonal treatment significantly inhibits (Na+-K+)-ATPase activity, and at the same time decreases membrane fluidity.