Synthese des Neopodophyllotoxins und der Podophyllinsäure

Summary Methanolysis of podophyllotoxin (I) with ZnCl₂ as catalyst yields podophyllinic acid methyl ester (IV) and neopodophyllotoxin (V), a new isomer of podophyllotoxin. Neopodophyllotoxin which contains the lactone group in the 1,3-position is stereospecifically hydrolyzed by alkali to the hitherto unknown podophyllinic acid (VI).

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12. Mitteilung über mitosehemmende Naturstoffe.     

Appetite stimulating effect of barbiturate-induced therapeutic sleep

Zusammenfassung Im Gegensatz zum Chlorpromazin- und bedingt reflektorischen Heilschlaf l?st die Medikation von kleinen Dosen kurzwirkender Barbiturate w?hrend der 14t?gigen Schlafperiode bei Geschwürkranken und Neurotikern eine zeitweilige Hyperphagie verschiedenen Grades aus. Der relative Anteil von einzelnen mitbeteiligten Mechanismen wird diskutiert.      

The influence of magnesium and calcium ions on the force produced in rigor muscle

Zusammenfassung Die Rigorspannung glycerinextrahierter Skeletmuskelfasern (Caiman crocodilus) und fibrillärer Insektenflugmuskelfasern (DLM) (L. maximus) konnte durch Zugabe von zweiwertigen Kationen und pH-Erniedrigung reversibel erniedrigt werden sowie durch pH-Erhöhung und Zugabe von Sulfationen erhöht werden. Da unter ähnlichen Bedingungen im Rigor Veränderungen des Abstandes von Aktin- und Myosinfilamenten nachgewiesen wurden^4,5, wurden die beobachteten Spannungsänderungen im Rigor auf Grund neuerer Crossbridgemodelle^3,9 diskutiert.

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We are grateful to Prof. Dr.J. C. Rüegg for helpful suggestions.

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Supported by Deutsche Forschungsgemeinschaft, Grant No. Ru 154/7.     

Synaptic development in brains of rats exposed perinatally to ethanol

Summary Development of brain synaptosomal uptakes of³H-norepinephrine and³H-dopamine in pups whose mothers received ethanol were nearly normal. However, development of synaptosomal uptake of³H-serotonin was significantly lower than in controls, while uptake of³H-norepinephrine into synaptic storage vesicles was increased.The authors thank F.J. Seidler and W.L. Whitmore for their technical assistance. Research was supported by U.S. Public Health Service grants AA-02935 and DA-00465. TAS is recipient of Research Scientist Development Award DA-00006 from the National Institute on Drug Abuse, and SMS is recipient of Research Scientist Award MH-06489 from the National Institute of Mental Health.     

Structure and thermal history of the H-chondrite parent asteroid revealed by thermochronometry

Our Solar System formed approximately 4.6 billion years ago from the collapse of a dense core inside an interstellar molecular cloud. The subsequent formation of solid bodies took place rapidly. The period of &<10 million years over which planetesimals were assembled can be investigated through the study of meteorites. Although some planetesimals differentiated and formed metallic cores like the larger terrestrial planets, the parent bodies of undifferentiated chondritic meteorites experienced comparatively mild thermal metamorphism that was insufficient to separate metal from silicate. There is debate about the nature of the heat source as well as the structure and cooling history of the parent bodies. Here we report a study of 244Pu fission-track and 40Ar-39Ar thermochronologies of unshocked H chondrites, which are presumed to have a common, single, parent body. We show that, after fast accretion, an internal heating source (most probably 26Al decay) resulted in a layered parent body that cooled relatively undisturbed: rocks in the outer shells reached lower maximum metamorphic temperatures and cooled faster than the more recrystallized and chemically equilibrated rocks from the centre, which needed approximately 160 Myr to reach 390K.