Strain difference in sex ratio response of mice to lactate dehydrogenase virus infection

Zusammenfassung Durch Infektion mit LDH-Virus wird bei Mäusen, deren Nachkommen normalerweise ein Geschlechtsverhältnis <1 aufweisen, ein solches von 1 erreicht. Da sich die Infektion der Eltern beider Stämme nicht in einer unterschiedlichen Zunahme der Serum-LDH, wohl aber in einer solchen der Spermien-LDH auswirkt, wird angenommen, dass die LDH-Aktivität der Spermien sich in einer zwar noch unbekannten Weise auf das Geschlechtsverhältnis der Nachkommen auswirkt.

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Supported by a grant from the Maryland Division of the American Cancer Society.     

Magnetic vortex core reversal by excitation with short bursts of an alternating field

The vortex state, characterized by a curling magnetization, is one of the equilibrium configurations of soft magnetic materials and occurs in thin ferromagnetic square and disk-shaped elements of micrometre size and below. The interplay between the magnetostatic and the exchange energy favours an in-plane, closed flux domain structure. This curling magnetization turns out of the plane at the centre of the vortex structure, in an area with a radius of about 10 nanometres--the vortex core. The vortex state has a specific excitation mode: the in-plane gyration of the vortex structure about its equilibrium position. The sense of gyration is determined by the vortex core polarization. Here we report on the controlled manipulation of the vortex core polarization by excitation with small bursts of an alternating magnetic field. The vortex motion was imaged by time-resolved scanning transmission X-ray microscopy. We demonstrate that the sense of gyration of the vortex structure can be reversed by applying short bursts of the sinusoidal excitation field with amplitude of about 1.5 mT. This reversal unambiguously indicates a switching of the out-of-plane core polarization. The observed switching mechanism, which can be understood in the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application in data storage.     

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Cellular and Molecular Life Sciences -     

Nouveaux livres

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Reviews

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The structure of amoorastatone and the cytotoxic limonoid 12-hydroxyamoorastatin

Summary 2 new limonoid-type terpenes have been isolated from an aqueous extract of seeds produced by the Eastern Himalayan (India) plantAphanamixis grandifolia Bl. By interpreting principally mass spectral and nuclear magnetic resonance data, the structures of 12-hydroxyamoorastatin (2b) and amoorastatone (3) were elucidated. Unequivocal evidence for the 12-hydroxyamoorastatin structural assignment was obtained by chemical conversion to sendanin (4). Amoorastatin derivative2b was found to significantly inhibit growth of the murine P388 lymphocytic leukemia cell lines but amoorastatone in the same system was inactive. In a comparative biological study, sendanin (4) and anthothecol (7) were also found significantly to inhibit growth of the P388 cell line, while rohitukin (8) and limonin (9) were found to be inactive.Part 63 of the series Antineoplastic Agents. For the previous contribution refer to G.R. Pettit, T.S. Krupa and R.M. Reynolds, Int. J. Peptide Protein Res., in preparation. The present investigation was supported in part by Public Health Research Grant No. CA-16049-05 from the National Cancer Institute, the Fannie E. Rippel Foundation, Mrs Mary Dell Pritzlaff, the Spencer T. and Ann W. Olin Foundation, Mr John F. Schmidt, and the Phoenix Coca-Cola Bottling Company.     

The homo-isoflavones III. isolation and structure of punctatin, 3,9-dihydro-punctatin, 4′-O-methyl-3,9-dihydro-punctatin, 4′-demethyl-eucomin and 4′-demethyl-5-O-methyl-3,9-dihydro-eucomin

Zusammenfassung Aus den Zwiebeln vonEucomis punctata L'Hérit. (Liliaceae) wurden 5 neue Homoisoflavone isoliert und ihre Struktur aufgeklärt.     

Effects of dimethylsulfoxide (DMSO) and potassium chloride on the resting potential of the isolated frog nerve

Zusammenfassung Da DMSO da Ruhepotential depolarisiert, verglichen wir seine Wirkung mit der von Kaliumchlorid. Infolge verschieden schneller Depolarisationen und einer jahreszeitlich abhängigen Ruhepotentialänderung durch Kaliumchlorid schliessen wir auf unterschiedliche Wirkungsmechanismen beider Substanzen. DMSO hat ausser einer Kurzzeitwirkung einen länger persistierenden reversiblen Effekt auf die Nervenmembran, der durch nachfolgende kurzwirksame Kaliumchloriddepolarisationen nachgewiesen werden kann.

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Acknowledgement: The authors express their appreciation to MissMonika Höcker for her skillful technical assistance.     

An apparatus for investigation of heterogeneous reactions in a flow system

Zusammenfassung Es wird eine Apparatur zum Studium heterogener und pyrolytischer Reaktionen in Fliess-Systemen beschrieben, die für flüssige und gasförmige Ausgangsstoffe, Reaktionsprodukte sowie für deren Mischungen geeignet ist.     

Developmental characteristics of histamine methyltransferase and phenylethanolamine-N-methyltransferase of rat brain

Summary The specific activity of histamine methyltransferase of rat brain increases rapidly from the 16th until the 25th day of gestation (7 days after birth). The specific activity of phenylethanolamine-N-methyl-transferase shows a rapid incrase during the 1st and the 2nd week after birth, the adult values being obtained by the end of the 2nd week.