Über den zeitlichen Ablauf der Aktivierung von Cyclophosphamid im Menschen und die Testung der zytostatisch aktiven Form an Ehrlich-Mäuse-Aszites-Tumorzellen

Summary The cytostatic action of human blood serum, following intravenous injection of cyclophosphamid, on cell proliferation and lactic production of Ehrlich mouse ascites tumour cells in vitro was tested. The maximum cytostatic activity was found 2 h after injection.     

A role for Drosophila LKB1 in anterior-posterior axis formation and epithelial polarity

The PAR-4 and PAR-1 kinases are necessary for the formation of the anterior-posterior (A-P) axis in Caenorhabditis elegans. PAR-1 is also required for A-P axis determination in Drosophila. Here we show that the Drosophila par-4 homologue, lkb1, is required for the early A-P polarity of the oocyte, and for the repolarization of the oocyte cytoskeleton that defines the embryonic A-P axis. LKB1 is phosphorylated by PAR-1 in vitro, and overexpression of LKB1 partially rescues the par-1 phenotype. These two kinases therefore function in a conserved pathway for axis formation in flies and worms. lkb1 mutant clones also disrupt apical-basal epithelial polarity, suggesting a general role in cell polarization. The human homologue, LKB1, is mutated in Peutz-Jeghers syndrome and is regulated by prenylation and by phosphorylation by protein kinase A. We show that protein kinase A phosphorylates Drosophila LKB1 on a conserved site that is important for its activity. Thus, Drosophila and human LKB1 may be functional homologues, suggesting that loss of cell polarity may contribute to tumour formation in individuals with Peutz-Jeghers syndrome.     

Intraaxonal iodate inhibits sodium inactivation

Zusammenfassung Iodat (IO ₃ ^– )-Ionen hemmen den Inaktivierungsvorgang des Natriumsystems, falls sie intraaxonal durch Diffusion vom abgeschnittenen Ende einer markhaltigen Froschnervenfaser her ans Innere der Schnürringmembran gelangen. Mit der Spannungsklemme erhält man dann in TEA-Ringer eine Strom-Spannungskurve des Natriumsystems auch mit lang dauernden Potentialänderungen. In der Stromklemme lassen sich unter diesen Umständen Aktionspotentiale mit Dauern bis zu 1 min registrieren.

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Dedicated to Prof. A. vonMuralt on the occasion of his 70th birthday.

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Sponsored by the Deutsche Forschungsgemeinschaft Sonderforschungsbereich 38 — Membranforschung.     

Ein neues Alkaloid aus dem Mycel einesClaviceps purpurea-Stammes. Zur Biogenese von Ergocristin

Summary A new alkaloid from the lyophilized mycelia of aClaviceps purpurea strain, N-[N-(d-Lysergyl)-l-valyl]-l-phenylalanyl-d-prolin-lactam, has been isolated and characterized. From its fast methanolysis it is deduced that the previously reported N-(d-Lysergyl)-l-valinmethylester is actually an artefact. The biogenetic significance and its possible role in biogenesis of Ergocristine is discussed.     

Monoclonal antibodies against antigens on breast cancer cells

Of 360 mAb obtained in a cell fusion experiment with the spleen cells of a mouse immunized with a mixture of different human breast carcinoma cell lines, 30 mAb were selected which reacted more strongly with tumor cells than with (noncancerous) fibroblasts. These mAb were tested for reactivity with additional types of cancerous and noncancerous tissues. Two mAb showed high tumor selectivity, but the corresponding epitopes on individual tumor cells were heterogeneously expressed. The mAb will be evaluated for in vivo applications.