Tissue ascorbic acid and a liver dehydroascorbatase in guinea-pigs

Summary The extraction, partial purification and assay of a dehydroascorbatase from guinea-pig liver is described. There was no evidence that changes in dehydroascorbatase activity could account for the modified tissue ascorbic acid concentrations associated with ageing or with the ingestion of fluoride, flavonoids or anthocyanin material.Supported by a Beechams Products grant.     

Tissue ascorbic acid and a liver dehydroascorbatase in guinea-pigs.

The extraction, partial purification and assay of a dehydroascorbatase from guinea-pig liver is described. There was no evidence that changes in dehydroascorbatase activity could account for the modified tissue ascorbic acid concentrations associated with aging or with the ingestion of fluoride, flavonoids or anthocyanin material.     

Effect of heparin pretreatment on stress-induced adrenal ascorbic acid changes in the rat

Zusammenfassung Vorbehandlung mit Heparin hat keinen Einfluss auf die Verminderung der Ascorbinsäure der Nebennierenrinde nach Verabfolgung von Natriumsalicylat, Epinephrin, Histamin und Kälteeinwirkung.

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Holder of a Lederle Medical Research Fellowship, at the University of Saskatchewan, College of Medicine, from June 1 to August 31, 1954.     

Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus)

Summary Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.Acknowledgment. The authors' thanks are due to Prof.C. Deb, Head of the Department of Physiology, Calcutta University, for encouragements.     

Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus).

Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.     

Effect of age on the ascorbic acid content of the liver ofCalotes versicolor

Zusammenfassung Eine altersabhängige Konzentrationsänderung der Ascorbinsäure in der Leber vonCalotes versicolor wurde festgestellt: Auf einen allmählichen Konzentrationsanstieg erfolgt eine entsprechende Abnahme. Vergleiche mit der Rattenleber wurden durchgeführt.     

Effect of caffeine on adenosine-induced heart block in guinea-pigs

Zusammenfassung Adenosin (0,25 mg/kg i.v. und mehr) ruft beim Meerschweinchen einen vorübergehenden atrioventrikulären Herzblock hervor. Coffein hat in Dosen von 1,25 mg/kg i.v. und mehr eine antagonistische Wirkung. Es wird angenommen, dass die Coffein-Wirkung auf der Beeinflussung des intrazellulären Ca⁺⁺ Haushalts beruht.

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Supported by institutional grants, Philadelphia General Hospital.     

Effect of cytosine arabinoside on thyroid autoimmunity in guinea-pigs

Zusammenfassung An einer Untersuchungsserie experimentell induzierter Autoimmunthyreoiditis beim Meerschweinchen wird gezeigt, dass Cytosine Atabinoside nur einen geringen suppressiven Effekt auf die Autoimmuninduktion hat und die Gewebezerstörung nicht zu verhindern vermag.

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This study was supported solely by a research gift from the Upjohn Pharmaceutical Company.     

Effect of parathion on the skin of guinea-pigs

Zusammenfassung Nach täglicher Applikation of Parathion werden histologisch Veränderungen der Meerschweinchenhaut festgestellt.     

Ascorbic acid: Effect of high doses on brain and heart catecholamine levels in guinea-pigs and rats

Zusammenfassung Längerdauernde Zufuhr hoher Dosen von Ascorbinsäure (1000 mg/kg) senkt bei Meerschweinchen, nicht aber bei Ratten, den Noradrenalin-Spiegel im Herzen signifikant. Hingegen wird bei beiden Tierspezies der Noradrenalin-Spiegel im Hirn nicht verändert.     

Ascorbic acid and cholesterol: Effect of graded oral intakes on cholesterol conversion to bile acids in guinea-pigs

Summary A significant correlation between liver ascorbic acid (AA) and total bile acids or liver bile acids has been established in guinea-pigs by direct determination of the bile acids, confirming an earlier hypothesis. The oxidation of cholesterol to bile acids is dependent on the AA status, but it cannot be further stimulated by AA when the animals are already on an adequate intake of the vitamin. This suggests that AA has a hypocholesterolaemic effect over a limited range of AA status.     

Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Biosynthesis of ascorbic acid in chick embryos

Summary Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples