Villus growth and cell replacement in the small intestine of the neonatal pig

Summary Cells produced in the crypts of newborn pig ileum migrate onto villi during development. There is little or no corresponding loss of cells from villus tips during the first week of postnatal life. Villus growth during this period is largely responsible for the slow rate of cellular renewal seen to take place.     

Differentiation antigens in keratinocytes]

By means of indirect immunofluorescence with human sera it has been demonstrated that cytoplasmic components of the basal cell layer showed antigenic differences as compared to the upper cell layers. Moreover there were differences whether the cells were involved in a mucous, a parakeratinized or an orthokeratinized differentiation.     

Interferon-dependent induction of mRNA activity for (2'-5')oligo-isoadenylate synthetase

At least three different enzymes involved in the regulation of protein synthesis are induced in a variety of cells by interferon (IFN). Sensitive assays for these enzymes have been developed and used to establish the specificity, dose dependence and time course of their induction by IFN. One of these enzymes, the oligo-isoadenylate synthetase E, whose product (2'-5')pppApApA activates the latent ribonuclease F, is increased over 50-fold after IFN treatment. We describe here the assay for an mRNA from IFN-treated mouse L cells, that produces oligo-isoadenylate synthetase activity when injected into Xenopus oocytes. This mRNA is found in the cells only after exposure to IFN. The mRNA increases in mouse L cells with the same time course as the enzyme activity itself. In particular, there is a 3-h lag period between IFN addition and the onset of enzyme and mRNA accumulation. Using anti-IFN antibodies, we show that during this lag period the continued interaction of IFN with the cells is necessary for the full induction of the oligo-isoadenylate synthetase.     

Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine

Summary Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.     

125I-Insulin is preferentially internalized in regions of the hepatocytes rich in lysosomal and Golgi structures

Summary ¹²⁵I-Insulin initially localizes to the plasma membrane of isolated rat hepatocytes but is subsequently internalized and preferentially associates with lysosomal structures. In the present study, we show that this preferential association to lysosomes occurs in regions of the cell rich in lysosomal and Golgi structures.This work was performed while Dr Gorden was visiting professor of the Institute of Histology and Embryology, University of Geneva, Geneva, Switzerland.This work was supported by grant No. 3.120.77 from Swiss National Science Foundation. We thank M.M. Sidler-Ansermet, O. Jerotic and N. Maalaoui for their valuable help.     

The effects of oxamate on the contractility of isolated rat atria

Zusammenfassung Oxamat, das die Lactat-Dehydrogenase hemmt, erniedrigt die Kontraktionsfähigkeit des Vorhofs mit und ohne Anwesenheit von Glucose im Medium und bei Hinzufügung von 2-DG oder Atropin. Hohe Konzentration von Pyruvat erhöht die Depression von Oxamat auf den Vorhof im Glucose-Milieu. Oxamat sensibilisiert das Gewebe für funktionellen Abbau durch Glycolyse.

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This research was supported by grants No. 1441 and No. HE-994801 from Consejo Nacional de Investigaciones de la República Argentina, and from the National Institute of Health, respectively.

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Research Fellow from the Consejo Nacional de Investigaciones de la República Argentina.

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Established Investigator from the Consejo Nacional de Investigaciones de la República Argentina.     

Intracellular localization and heterogeneity of alkaline phosphatase of Yoshida ascites sarcoma

Zusammenfassung In Yoshida-Sarkomzellen ist die alkalische Phosphatase vorwiegend in der partikelfreien Fraktion in gelöster Form lokalisiert. Gelfiltration fÜhrt zu einer Auftrennung des Enzyms im partikelfreien Überstand von 6 Fraktionen, des Enzyms in den Zellkernen bei 2 Fraktionen.

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We are grateful to Tenovus (Wales) for financial support.     

The margin of overgrowth of the embryonic chick blastoderm as a study model for cell-to-cell contacts

Zusammenfassung Die Entwicklung vom «margin of overgrowth» junger Hühnerkeime ist verschieden nach Kontakt mit Helazellen und mit Mesonephros oder Hautgewebe; die ersteren hemmen die Entwicklung, die anderen werden vom Keim aufgenommen. Deshalb wird der «margin of overgrowth» als Modell für die Studie von Zellkontakten vorgeschlagen.