Quantitative studies on the influence of the temperature applied in freeze-substitution on P,N, and dry mass losses in fixed tissues

Résumé Les auteurs ont constaté que la température a une influence sur la diminution du contenu en azote et en phosphore et sur celle de la masse déséchée après l'usage de méthanol au cours de la congelation-dissolution (freeze-substitution) des tissus. Ces diminutions sont moins marquées à la temperature de – 79°C. Après l'usage d'acétone, les diminutions atteignent leur minimum.     

Investigation of the blood brain barrier permeability in experimental P avitaminosis

Zusammenfassung Eine erhöhte Permeabilität der Blut-Hirn-Schranke für Evans-Blau wurde bei Ratten nach einer Flavon-Mangeldiät festgestellt.     

Investigation of the physiologically different glycogen fractions in newborn rabbits

Zusammenfassung Es wird das Verhältnis von gebundenem und trichloressigsürelöslichem Glykogen in verschiedenen Muskeln, Leber und Lunge von neugeborenen und ausgewachsenen Kaninchen bestimmt und auf einen Zusammenhang zwischen Glykogenspiegel und Resistenz gegenüber Sauerstoffmangel hingewiesen; ferner auf Änderungen im Glykogenspiegel bei akutem Sauerstoffmangel und Hunger.     

Effect of different bathing media on the short-circuit current across the intestine of the rat and guinea-pig

Summary The changes in short-circuit current occurring when one or both solutions bathing the intestine of rat or guinea-pig mounted in flux chambers were recorded. The results with the guinea-pig can be explained in terms of diffusion potentials arising from the ionic replacements, and an electrogenic sodium pump, sensitive to ouabain, in the contraluminal membrane of the cell. In the rat, the situation is more complicated, and the enterocyte probably possesses an electrogenic sodium pump in the brush-border membrane.     

Effect of different bathing media on the short-circuit current across the intestine of the rat and guinea-pig.

The changes in short-circuit current occurring when one or both solutions bathing the intestine of rat or guinea-pig mounted in flux chambers were recorded. The results with the guinea-pig can be explained in terms of diffusion potentials arising from the ionic replacements, and an electrogenic sodium pump, sensitive to ouabain, in the contraluminal membrane of the cell. In the rat, the situation is more complicated, and the enterocyte probably possesses an electrogenic sodium pump in the brush-border membrane.     

Isethionate may not be an inert substitute for extracellular chloride in the central nervous system

Summary Replacement of extracellular chloride with isethionate or methylsulphate causes an increased efflux of 1-[¹⁴C]-GABA from the in vivo superfused rat cuneate nucleus. This raises the question of the suitability of these anions as inert substitutes for chloride in studies on the ionic dependency of membrane phenomena in the central nervous system.Supported in part by a grant from the Medical Endowment Funds of the University of Aberdeen.N. B. supported by grants from CAPES and FAPESP, Brazil, J. A. A. supported by grants from CNPq and FAPESP, Brazil.     

Membrane transport of Na and K and cell dehydration in sickle erythrocytes

The cellular concentration of Hb S plays a central role in the kinetic of Hb S polymerization and cell sickling. Blood of patients with homozygous sickle cell (SS) anemia contains a variable fraction of cells which are markedly dehydrated and have increased Hb S concentration. Since a decrease in cellular Hb S concentration reduces Hb S polymerization and sickling, the study of the processes leading to sickle cell dehydration has important pathophysiological and therapeutic implications. Sickle cell dehydration is due to cellular loss of K and Cl. K loss in sickle cells can take place via either the Ca²⁺-activated K⁺ channel, or the K?Cl cotransport, or the combined effect of oxidative damage and deformation of the red cell membrane. Inhibitors of K transport through these pathways could be used to prevent dehydration of sickle cells in vivo, provided that they can be administered safely.     

Effect of mercuric acetate on mobilization of N and P during germination and seedling growth ofCicer arietinum

Summary Mercuric acetate, at 5.0×10^–5 M, stimulates the mobilization of total nitrogen and phosphate reserves from cotyledons during seedling growth inCicer arietinum cv H208 whereas it suppresses the same process at 2.5×10^–4 M.Thanks are due to Dr D. Banerji for providing facilities and helpful suggestions.     

Synthesis and contractile activity of the C-terminal heptapeptide of substance P with N5-dimethyl glutamine in the 6-position. Active site studies

The synthesis and testing of [N5-dimethyl-Gln6]-SP5-11 showed 37 +/- 12% contractile activity relative to SP, and intrinsic efficacy 98 +/- 4%. This finding indicates that the carboxamide groups of the dual Gln5-Cln6 moiety are not equally related with the contractile response of the C-terminal heptapeptide of SP.     

Synthesis and contractile activity of the C-terminal heptapeptide of substance P with N5-dimethyl glutamine in the 6-position. Active site studies

Summary The synthesis and testing of [N⁵-dimethyl-Gln⁶]-SP_5–11 showed 37±12% contractile activity relative to SP, and intrinsic efficacy 98±4%. This finding indicates that the carboxamide groups of the dual Gln⁵-Gln⁶ moiety are not equally related with the contractile response of the C-terminal heptapeptide of SP.The authors wish to express their deep appreciation to Professor H. Niedrich and Dr J. Bergmann of the Institute of Drug Research, Academy of Sciences of DDR, Berlin, for their valuable help in providing the biological data.     

Persisting circadian rhythm in hepatic glycogen of mice during inanition and dehydration

Zusammenfassung Eine Circadianrhythmik des Mäuseleberglycogens lässt sich durch Standardisierung anderer biologischer Frequenzen und «Lärm» isolieren. Dies gelingt auch nach Entzug von Futter oder Futter und Wasser. Persistente Rhythmen mit grosser Amplitude kennzeichnen eine Reihe physiologischer Funktionen nach Futter- und Flüssigkeitsentzug und können als Chossatphänomene bezeichnet werden.

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Work supported by the Elsa U. Pardee Foundation, the National Aeronautics and Space Administration of the USA (NsG-517) and the US Public Health Service (5-K6-GM-13).     

Neurotrophic effects of conditioned media of astrocytes isolated from different brain regions on hippocampal and cortical neurons

The present study was designed to reveal whether astroglial cells from different brain regions produce diffusible factors that differentially support the survival of neurons and the establishment of neuronal morphology. For this purpose, astrocyte conditioned media (ACM) were prepared by conditioning chemically-defined medium with type I astrocyte culture dissociated from cerebral cortex, hippocampus and hypothalamus. Hippocampal and cortical neurons were cultured in ACM or in non-conditioned medium. ACM derived from three brain regions all supported the survival of hippocampal and cortical neurons better than non-conditioned control medium. Of these, hypothalamic ACM was the most effective in supporting the survival of cortical neurons. The ACM also potentiated the elongation of the longest neurite of hippocampal and cortical neurons. However, there were no significant differences in the promoting effects on neurite elongation among ACM from three brain regions.     

A comparison of the degree of chimaerism produced when allogeneic cells from four different tissues are used to create tolerance in the mouse

Résumé La tolérance immunologique produite chez la souris avec les cellules de foie d'embryon, ou des cellules de rate, de tissus lymphoïdes ou de moelle osseuse d'adulte, a été comparée au degré de chimérisme. Le foie d'embryon a produit le plus haut degré de chimérisme (10,7%).