The application of fluorescent-antibody test to cysts ofEntamoeba invadens

Zusammenfassung Die Methode fluoreszierender Antikörper wurde zur Darstellung von Blasen beiEntamoeba invadens benützt. Sowohl mit nativen, wie auch mit fixierten Zellen konnte eine befriedigende Reaktion erzielt werden. Formalin erwies sich als günstigstes Fixationsmittel.     

Antigenic relationship between the cysts and trophozoites ofEntamoeba invadens

Résumé La technique des anticorps fluorescents a été appliquée à l'étude de la relation antigénique des cystes et des trophozoïtes d'Entamoeba invadens. Le sérum anticyste préalablement absorbé par les trophozoïtes a montré chez ces derniers une fluorescence négligeable mais il continua a produire une fluorescence intense chez les cystes, ce qui indique que les antigènes de surface des cystes sont différents de ceux des trophozoïtes.     

Synaptogenesis in hippocampal cultures

Hippocampal cultures offer unique advantages for the study of neuronal development and synaptogenesis. Studies performed on this model enabled dissection of the temporal sequence of events which lead to the differentiation of pre- and postsynaptic compartments. Received 27 January 1999; received after revision 4 March 1999; accepted 5 March 1999     

Slice cultures of cerebellar,hippocampal and hypothalamic tissue

Summary Cerebellar, hippocampal and hypothalamic slices prepared from newborn and 7-day-old rats were cultured by means of the roller-tube technique. Identification of cells was made easier by the fact that at least part of the characteristic cytoarchitecture of the tissue was preserved in vitro. Cerebellar Purkinje cells and neurones of the deep cerebellar nuclei were recognized on the basis of their size, their location within the culture and their dendritic arborization. Pyramidal cells of all hippocampal subfields displayed their characteristic basal and apical dendritic trees with numerous spinous processes. Hippocampal granule cells gave rise to a monopolar dendritic arbor; their axons terminated in the dentate hilus and CA3 region. Golgi-like immuniperoxidase staining allowed localization of groups of neurophysin-positive neurones in slices prepared from the anterior hypothalamus. These neurones, bilaterally bordering the third ventricle, usually displayed a simple dendritic arborization and fine beaded axons.—Cultivation of brain slices prepared from young rats offers particular advantages in that the cultured cells are organized in an organotypic monolayer and individual living neurones may be directly visualized.Acknowledgments. I would like to thank Dr J. Zimmer and Dr M. Sofroniew for their valuable help with the Timms and immunoperoxidase staining techniques and Mr R. Schlichter and L. Wohlfart for illustrating the culture procedure. The excellent technical assistance of Ms L. Rietschin and E. Hoffmann is gratefully acknowledged.     

Paper tools in experimental cultures

The paper studies various functions of Berzelian formulas in European organic chemistry prior to the mid-nineteenth century from a semiotic, historical and epistemological perspective. I argue that chemists applied Berzelian formulas as productive ‘paper tools’ for creating a chemical order in the ‘jungle’ of organic chemistry. Beginning in the late 1820s, chemists applied chemical formulas to build models of the binary constitution of organic compounds in analogy to inorganic compounds. Based on these formula models, they constructed new classifications of organic substances. They further applied Berzelian formulas in a twofold way to experimentally investigate organic chemical reactions: as tools which supplemented laboratory tools and as tools for constructing interpretive models of organic reactions. The scrutiny of chemists' performances with chemical formulas on paper also reveals a dialectic which contributed considerably to the formation of the new experimental culture of synthetic carbon chemistry that emerged between the late 1820s and the early 1840s. In an unintended and unforeseen way, the tools reacted back on the goals of their users and contributed to conceptual development and a shift of scientific objects and practices (‘substitution’) which transcended the originally intended chemical order.     

Hydroxyproline production in chick fibroblast cultures

Zusammenfassung Kulturen von Hühnerherzfibroblasten wurden nach 10, 21 und 28 Tagenin vitro auf ihren Gehaltan Hydroxyprolin — einer wichtigen Aminosäure des Kollagens — untersucht. Nach 10, bzw. 21 Tagen ist eine signifikante, durch Prolinzugaben nicht beeinflussbare Vermehrung des zu 50% löslichen Hydroxyprolins feststellbar.

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Kantonsspital, Chur.     

Effect of L-amino-ethyl-cysteine,a sulfur analogue of L-lysine,on virus miltiplication in mammalian cell cultures

Summary L-amino-ethyl-cysteine clearly inhibits replication of Mengovirus; another RNA-virus (vesicular stomatitis virus) is completely insensitive. Protein synthesis is not impaired, but no active viral RNA-polymerase is detected.This work was partly supported by grant No. 73.01407.44 115.0107 of Consiglio Nazionale delle Ricerche, Roma, Italy. The technical collaboration of P. Meo and G. Conciatori is gratefully acknowledged.     

Some new aspects in human trophoblast cultures

Résumé L'évolution morphologique des cellules trophoblastiques humaines, ainsi que leur potentiel de sécrétion hormonale, in vitro, ont été examinés pendant plus de 2 mois, à l'aide d'une technique simplifiée de culture de placenta. La signification des cellules dites «géantes» l'aspect fibroblastique des trophoblastes dans les cultures agées, et le développement des vrais fibroblastes dans ces cultures, sont discutés.

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Acknowledgments: We thank Mr.I. Ofek and MissTechila Kehati for technical assistance.