The nature and synthetic capacity of fragile cells ofBacillus megatherium partly deprived of cell walls

Zusammenfassung Kurzfristige Einwirkung von Lysozym in Phosphatpufferlösung aufBazillus megatherium ergibt Zellen mit bis zur Hälfte reduzierter Zellwand. Solche «fragile Zellen» sind gegen osmotische Schocks empfindlich und lassen sich in Formen überführen, die ausser der cytoplasmatischen Membran nur Zellwandreste besitzen. « Fragile Zellen » (auch von ihnen hergeleitete sedimentäre Formen) behalten die Fähigkeit der Zellwandsynthese. Sie sind fähig, in Medien, die 10% Saccharose enthalten, in eingeschränktem Masse sich zu normalen Zellen zu regenerieren.     

Effect of dipyridamole and adenosine monophosphate on cell proliferation in the hemopoietic tissue of normal and gamma-irradiated mice

Combined treatment with dipyridamole and adenosine monophosphate enhances cell proliferation in the hemopoietic tissue of normal and gamma-irradiated mice. This effect can be explained by the elevation of extracellular adenosine, and the receptor-mediated activation of the cell adenylate cyclase system.     

A biologically active analogue of oxytocin not containing a disulfide group

Zusammenfassung Die Synthese eines Analogen des Deamino-oxytocins, in dem ein Schwefelatom der Disulfidbrücke durch eine Methylengruppe ersetzt ist (I,X = CH₂,R=H), wird beschrieben. Die Verbindung hat oxytocinähnliche biologische Wirkungen.     

Tissue-specific inhibition of embryonic neural cell proliferation by rat brain extract

Summary The effect of rat brain tissue extract on the proliferative activity of chicken embryonic neural tube and other tissues was studied. Only tissue-specific inhibitory action was found to be similar to substances of the chalone group.     

Cortical acetylcholinesterase and ‘handedness’ in rats

Zusammenfassung Nachweis, dass es beim Lernprozess zu einem Anstieg der Acetylcholinesterase im kortikalen Repräsentationsareal einer trainierten Extremität der Ratte kommt.     

Adaptation to intermittent fasting as a factor modifying the radiation resistance of mice

Summary Mice adapted to intermittent food intake (24 h fasting:24 h feeding) for 2–3 weeks exhibit a higher resistance to whole-body gamma irradiation. This is manifested by increased survival of animals and a more effective recovery of blood leukocyte counts.     

Superallowed Gamow-Teller decay of the doubly magic nucleus 100Sn

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During β(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of (100)Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the β-decay of (100)Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear β-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, (100)In, are well reproduced by modern, large-scale shell model calculations.