Sorbitol dehydrogenase in Anas platyrhynchos and Zenaida auriculata auriculata during development.

Sorbitol dehydrogenase (E.C.N. 1.1.1.14) was studied in liver, kidney and gonads of Zenaida auriculata auriculata (golden pigeon) and of Anas platyrhynchos (creole domestic duck) from South American faunes. The specific activity of SDH increased from embryonic to adult stage and is higher in the Anas platyrhynchos tissues. The electrophoretic studies performed in liver and kidney of both species during development showed variations in the number and intensity of the bands in accordance with the age and the species.     

Corticotrophin-releasing action of adrenaline,serotonin and pitressin

Zusammenfassung Der Einfluss von Serotonin, Adrenalin und Pitressin auf den Mechanismus der ACTH-Ausschüttung durch den Hypophysenvorderlappen wurde unter verschiedenen experimentellen Bedingungen untersucht.Bei normalen Ratten zeigten alle geprüften Pharmaka auf die Adenohypophyse eine stimulierende Wirkung, welche nach der Abnahme des suprarenalen Askorbinsäuregehaltes beurteilt wurde.     

Characterization of prehistoric flint mine products

Trace element analyses of flint show statistically valid differences between products of major British and European Neolithic flint mines.     

Morphological effects of serotonin and ketanserin on embryonic chick skin in vitro

Summary Cell and organotypical cultures are used to study the direct effect of serotonin and of ketanserin, a serotonin antagonist, on dermal and epidermal cells of embryonic chick skin. Ketanserin stimulates the increase in cell number and inhibits the differentiation, whereas serotonin stimulates differentiation and inhibits the increase in cell number.     

Endocytotic activity in lizard erythroblasts

Zusammenfassung In Eidechsen-Erythroblasten mit Blutungsanämie wurden elektronenmikroskopisch Zellorganellen und eine aktive Pinocytose nachgewiesen bei gleichzeitiger Aktivitätssteigerung der sauren Phosphatase, die durch Eisenzufuhr noch-verstärkt wurde.

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Dr. C. C.Monteiro carried out this work with the aid of a grant from the Gulbekian Foundation, Lisboa (Portugal).     

Histologische und zytologische Untersuchungen über das Ependym und seine Abkömmlinge (insbesondere die Epiphyse und den Saccus vasculosus) bei niederen Vertebraten

Summary In the brain wall of different vertebrate species, ependymal cells of different type occur. These cells possess protuberances which protrude into the ventricle.Although cytologically these structures are all variations of one theme, they must at present be interpreted in different ways as regards function.Probably these cell types form a complex system for the regulation of the cerebrospinal fluid. It remains possible that one or more of these cell types act as light receptors.     

Ca2+ channel modulation by 8-bromocyclic AMP in cultured heart cells

Modulation of ion channels is of increasing interest as it is an important step in the regulation of cellular functions. We have analysed the effect of 8-bromocyclic AMP on Ca2+ channels in cultured cardiac cells by the patch-clamp method and report here that there was a large increase in the probability of opening of the channels. On the basis of a recently proposed kinetic reaction scheme we suggest that cyclic AMP-dependent phosphorylation of Ca2+ channels primarily promotes the forward rate constants which lead to the open state of a Ca2+ channel during depolarization.