Enhancement by caffeine of sister-chromatid exchange frequency induced by antineoplastic agents in human lymphocytes

Summary The SCE frequency induced by Thiotepa and the effect of this antineoplastic drug in combination with caffeine have been studied in cultures of human peripheral blood. Caffeine was found to enhance SCE and breakage frequencies induced by Thiotepa in human lymphocytes.Acknowledgment. I am deeply grateful to Dr M.J.W. Faed, for stimulating discussions, guidance and constructive criticism. This paper is a part of my Ph.D. thesis submitted to Dundee University.     

Enhancement by caffeine of sister-chromatid exchange frequency induced by antineoplastic agents in human lymphocytes.

The SCE frequency induced by Thiotepa and the effect of this antineoplastic drug in combination with caffeine have been studied in cultures of human peripheral blood. Caffeine was found to enchance SCE and breakage frequencies induced by Thiotepa in human lymphocytes.     

Enhancement of ethylemethane sulfonate-induced mutation frequency inDrosophila by dimethyl sulphoxide

Zusammenfassung Die mutagene Wirkung von Aethylenmethansulfonat inDrosophila-Männchen wird durch DMSO um 46% erhöht. DMSO allein kann keine Mutation über die Spontanrate hinaus induzieren.     

Zinc ions block the intracellular calcium release induced by caffeine in guinea-pig taenia caeci

Zn²⁺ in low concentrations (0.005–0.1 mM) inhibited the transient contractions in response to caffeine (25 mM) in a dose-dependent manner in smooth muscle of intact guinea-pig taenia caeci. At Zn²⁺ concentrations higher than 0.1 mM, caffeine did not elicit any response. After saponin-treatment of the fibres, which leaves the Ca²⁺ storage sites intact, caffeine contraction was completely inhibited by Zn²⁺ at a relatively low concentration (0.03 mM). However, in Triton-X-100-treated fibres, in which the Ca²⁺ release sites are destroyed, the contraction could be induced in the presence of Zn²⁺ by an increase in Ca²⁺. In conclusion, Zn²⁺ can block the intracellular Ca²⁺ release from caffeine-sensitive release sites in taenia caeci.     

Monocentric nature of the chromosomes ofRanatra (heteroptera) verified by the induced fragmentation experiments

Résumé Les chromosomes deRanatra filiformis Fabr. (Heteroptera) a été exposé à la radiation gamma de 5000 à 10000r à raison de 4,45 Kr/min. Dans beaucoup de cellules, les fragments du chromosome, ainsi produits, atteignent le pÔle ou bien forment des ponts durant l'anaphase ou des masses irrégulières de chromatine. Un pareil comportement des fragments indiquent nettement que les chromosomes de ce genre sont monocentriques et non polycentriques.     

Enzymatic phosphorylation of proteins of rat liver chromatin by (γ-32P) ATP in vitro

Zusammenfassung Isoliertes Rattenleberchromatin baut die endständige Phosphat-Gruppe von (-³²P) ATP in seine Proteine in Form von Phosphatester von Serin und Threonin ein. Der Einbau ist Mg⁺⁺ und Mn⁺⁺ abhängig und steigt mit Erhöhung des pH des Inkubationsmediums an. Phosphat und Pyrophosphat stimulieren die Phosphorylierung, zyklisches AMP hat keinen Effekt. Die sauren Proteine werden viel stärker als die Histone phosphoryliert. Das eingebaute Phosphat wird sehr schnell freigesetzt, ein Prozess, der von der Anwesenheit von dephosphorylierenden Enzymen abhängt.     

Granulocyte colony formation in vitro: Enhancement by human placental (umbilical cord) serum

Summary Addition of human placental umbilical cord serum to bone marrow cultures reproducibly increased the number of granulocyte colonies in vitro. This stimulatory effect was significantly greater than that of fetal calf serum which was seen in cultures of human bone marrow under the conditions described.This work was financed by grant FOR. No. 004.AK.71 (1) from the Swiss Cancer League.The authors wish to express their gratitute to colleagues from Maternity Ward, Frauenspital, Bern, and Department of Thoracic and Vascular Surgery, Inselspital, Bern, through whose kind assistance samples of umbilical blood and fragments of ribs removed at thotacotomies were obtained. MissJ. Blom provided excellent technical assistance.     

Pseudolymphoma of skin induced by oriental hornet (Vespa orientalis) venom

Summary Intradermal injection of saline suspension ofVespa orientalis venom sac to 57 black mice caused a local nodule composed o flymphocytes, few histiocytes and plasma cells 10 to 12 days following the injection. This reaction simulates the pseudolymphoma reaction observed in humans following arthropode stings.     

Sleep induced by the administration of melatonin (5-methoxy-N-acetyltryptamine) to the hypothalamus in unrestrained cats

Zusammenfassung An nicht narkotisierten Katzen wurde die Wirkung einer direkten lokalen chemischen Reizung subkortikaler Strukturen durch Melatonin untersucht. Diese Substanz, appliziert im Bereich der Area praeoptica, löste trophotropische Effekte und Schlaf aus.     

Pseudolymphoma of skin induced by oriental hornet (Vespa orientalis) venom.

Intradermal injection of saline suspension of Vespa orientalis venom sac to 57 black mice caused a local nodule composed of lymphocytes, few histiocytes and plasma cells 10 to 12 days following the injection. This reaction simulates the pseudolymphoma reaction observed in humans following arthropode stings.