The effect of concanavalin-A on the reaggregation of cells dissociated from Xenopus laevis early embryos

Summary The effects of concanavalin-A on the reaggregation and sorting of cells from Xenopus laevis early embroys have been studied. The results suggest that at high concentrations, concanavalin-A can prevent reaggregation.     

A comparative study of the differentiation of dissociated nerve cells under different culture conditions

Summary In vitro differentiation of chick embryo brain cells was compared under several culture conditions. Morphological observations and acetylcholinesterase histochemical staining revealed that the development was similar in all conditions tested if cells have been derived from 7 days embryos. Considering the cultures from 11 days embryos, the cell dissociation by trypsin and the plastic surface proved to be the most favourable conditions in contrast to mechanical dissection and collagen surface.M. Sensenbrenner is Maitre de Recherche au CNRS.     

Two different iodinating systems in isolated thyroid cells

Résumé Deux systèmes distincts d'iodination ont été mis en évidence dans des préparations de cellules isolées de thyroide. Les résultats expérimentaux obtenus suggèrent une localisation intracellulaire à l'un des systèmes et extracellulaire à l'autre.

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Aspirant of the Fonds national de la recherche scientifique.     

A comparative study of the differentiation of dissociated nerve cells under different culture conditions.

In vitro differentiation of chick embryo brain cells was compared under several culture conditions. Morphological observations and acetylcholinesterase histochemical staining revealed that the development was similar in all conditions tested if cells have been derived from 7 days embryos. Considering the cultures from 11 days embryos, the cell dissociation by trypsin and the plastic surface proved to be the most favourable conditions in contrast to mechanical dissection and collagen surface.     

Histochemical study of dissociated nerve cells from embryonic chick cerebral hemispheres in flask cultures

Zusammenfassung Die Differenzierung von dissoziierten Grosshirnneuronen in Plastikflaschenkulturen wurde mit histochemischen Methoden, Nisslfärbung, Silberimprägnation der Nervenfasern und Acetylcholinesteraseaktivität untersucht.

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with the technical assistance ofM. F. Knoetgen

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Chargée de Recherche au C.N.R.S.     

ADP-induced platelet aggregation in vivo after exclusion of different circulatory districts.

The effect of the ADP infusion on the basal platelet count was studied in controls and in rats submitted to the exclusion of the following circulatory districts: splenic, renal, cerebral and of a hind-limb. After these exclusions the ADP-induced thrombocytopenia was less marked than the controls.     

Evidence for the presence of viable endothelial cells in cultures derived from dissociated rat brain

Summary The morphology and histochemistry of dissociated newborn rat brain was studied in tissue culture. Direct microscopy of developing cells, electron microscopy and the alkaline phosphatase activity were used to identify the capillary endothelial cells.Acknowledgments. We thank Dr J. Gripenberg for technical assistance. This research was supported by Finnish Cultural Foundation and carried out during the tenure of a fellowship provided for F. J. from the Finnish-Hungarian Cultural Exchange Program.     

Distribution and seasonal variation of toxic principles of sea-cucumber (Holothuria leucospilota brandt)

Zusammenfassung Die jahreszeitlichen Schwankungen des Saponingehaltes der SeegurkeHolothuria leucospilota Brandt wurde untersucht. Hohe Saponinkonzentrationen fanden sich besonders in Cuviers-Drüsen und in Ovarien mit Eiern. Höchste Saponingehalte werden von Juni bis August gemessen.     

Effects of drugs and ions on a primitive system of spontaneous contractions in a sponge (Euspongia officinalis)

Résumé ChezEuspongia officinalis, l'acetylcholine et l'adrénaline agissent comme excitateurs des contractions spontanées, localisées et brèves, et favorisent en outre l'extrusion des glycoprotéines contenues dans les cellules contractiles. Na⁺ et Ca⁺⁺ sont nécessaires au fonctionnement des pacemakers.

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This work was supported by the Centre National de la Recherche Scientifique (E.R.A. No. 183). We thank Dr.E. A. Robson for the help of her valuable criticisms.     

Effect of bromelain (ananase?) on human platelet aggregation

Zusammenfassung Die orale Verabreichung von Bromelain in Form von 2 Ananase^®-100-Tabletten an freiwillige Versuchspersonen verminderte bei diesen die Empfänglichkeit für die durch ADP induzierte Aggregation der Blutplättchen.

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This work was supported by the Honolulu Chamber of Commerce research grants.     

Stimulation of cell aggregation by theophylline in the asexual reproduction of fresh-water sponges (Ephydatia fluviatilis)

Résumé La formation de gemmules dans les éponges d'eau douce est fortement stimulée par la théophylline 10^–4 M, mais non par une augmentation globale de la concentration en adénosine monophosphate cyclique dans le milieu.     

State space trend-cycle decomposition of the ARIMA(1,1,1) process

It has been common practice to decompose an integrated time series into a random walk trend and a stationary cycle using the state space model. Application of state space trend-cycle decomposition, however, often results in a misleading interpretation of the model, especially when the observability of the state space model and the redundant relationships among the model parameters are not properly considered. In this study, it is shown that spurious trend-cycle decomposition, discussed by Nelson (1988), results from an unobservable state space model, and the usual assumption of independent noise processes in the model results in parameter redundancy. Equivalence relationships for the ARIMA(1,1,1) process and the state space model consisting of a random walk trend and an AR(1) cycle, where the noise processes of the trend and of the cycle are generally correlated, are also derived. © 1997 John Wiley & Sons, Ltd.     

Attraction ofScolytus scolytus (F.) to the components of Multilure,the aggregation pheromone ofS. multistriatus (Marsham) (Coleoptera: Scolytidae)

Summary The attraction ofS. scolytus to the components of Multilure is described. 4-Methyl-3-heptanol is an attractant which is synergised bya-cubebene. Multistriatin appears to be an inhibitor. A combination of 4-methyl-3-heptanol and cubeb oil is more effective as a bait forS. scolytus than Multilure.We thank Mr A. K. Hughes and Mr J. Boswell for their cooperation in allowing us to conduct experiments on Parham Estate; Mr D. Mobbs and Mr C. Thorne for the statistical analyses; Dr J. W. Peacock for samples of mixed isomers of multistriatin and distilled cubeb oil; Mrs J. Allsop and Mr N. J. Fielding for technical assistance. We are grateful to Mr D. Bevan, Dr J. H. Borden, Dr J. F. Grove and Prof. A. W. Johnson for their interest and encouragement.