Interaction of sulfonylurea with the pancreatic B-cell

Conclusions Sulfonylureas have a variety of effects on pancreatic B-cells. In the present review an attempt has been made to identify those that appear fundamental from a mechanistic point of view and in that sense common to all hypoglycemic drugs tested. On several points the available able experimental information is limited. With this reservation in mind, the following general hypothesis is presented for the insulin-releasing action of this class of drugs. Hypoglycemic sulfonylureas and related [(acylamino)alkyl]benzoic acids bind to the B-cell plasma membrane, a step in which hydrophobic anchoring is essential. Dissociated acidic COOH or SO₂NHCO groups in the drugs are thus presented to an ion-gating protein in the plasma membrane, possibly in the vicinity of a pair of sulfur atoms. The reduced state of these sulfurs is promoted, preventing the formation of a disulfide bridge. K⁺ permeability is thereby decreased, favoring depolarization of the B-cell and Ca²⁺ influx through voltage-dependent channels. Finally, Ca²⁺ triggers the physiological apparatus for discharge of the insulin secretory granules. The effect of this insulinreleasing signal chain is amplified by cyclic AMP which increases in the B-cell as a consequence of depolarization and Ca²⁺ influx. This hypothesis does not attribute an ionophoretic role to the sulfonylureas per sebecause various experiments with cells and artificial membrane systems render such an idea apparently less tenable.     

Isolation and some properties of the heparin-neutralizing factor (PF4) released from human blood platelets

Zusammenfassung Der in Form eines hochmolekularen Komplexes von den Plättchen freigesetzte, heparinneutralisierende Faktor (PF 4) konnte reversibel in ein Träger-Material und ein aktives Protein (Molekulargewicht ca. 30000) aufgespalten werden.

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This work was supported by the Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung.     

Drosophila enzyme-genetics: A table

Summary A method for the vacuum distillation of microgram amounts of substances is described.     

Effect of cerium on drug metabolizing activity in rat liver

Zusammenfassung Es wird gezeigt, dass i.v. injiziertes Cerium (2 mg/kg) eine hemmende Wirkung auf den Stoffwechsel von Arzneien in der Rattenleber hat.     

A new method for measuring membrane potentials with external electrodes

Zusammenfassung Beschreibung einer neuen Methode, die es gestattet, mit Aussenelektroden die wahre Grösse der Membranpotentialschwankungen, die durch den Einfluss von hyper- oder hypopolarisierenden Substanzen oder durch die Erregung in markhaltigen Nervenfasern erzeugt werden, zu registrieren.     

The histamine and heparin content of the rat's mesenterial mast cells regenerating after application of compound 48/80

Zusammenfassung Der Histamin- und Heparingehalt in Mastzellen, die nach totaler Zerstörung mit Histaminliberator 48/80 regenerieren, wird untersucht. Die Ergebnisse zeigen, dass während des Regenerationsprozesses die Anzahl der Mastzellen, in denen sich das Histamin mit Reineckesalzlösung anfärbt, kleiner ist, als die Anzahl der Mastzellen, die mit Toluidinblau darzustellen sind.     

Die Genomsonderung in den Mitosen der Rattenleber

Summary Model squashes with gelatine cubes containing 8 files like the chromosomes ofBellevalia romana (2n=8) showed the chromosomes only in groupings that correspond to the original position of metaphase chromosomes. The metaphase chromosomes in root tip cells ofBellevalia romana are arranged at random; there is neither somatic pairing nor genome segregation (= grouping of metaphase chromosomes into two complete chromosome sets). In contradiction to these results, the chromosomes in the regenerating liver cells (2n=42) show a certain precentage of grouping into complete genomes. It is concluded that in rat liver cells a mechanism exists which, starting with the genome segregation, may produce a change in chromosome number. Thus these same euploid or aneuploid chromosome numbers can be explained which are really observed in normal and treated rat liver. 4 possibilities of such mechanism are discussed.

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Nach einem Vortrag, gehalten anlässlich des IV. Symposium histologicum internationale Lausanne (Suisse), 5.–8. September 1961.     

Hypothalamic monoamines and pineal dopamine during the sexual differentiation of the rat brain

Zusammenfassung Der Gehalt an Monoaminen im Hypothalamus der Ratte wurde während der sexuellen Differenzierung bestimmt, wobei für das hypothalamische Noradrenalin eine signifikante Zunahme zwischen dem 4. und 10. Tag gefunden wurde.

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Supported by grants from The Yrjö Jahnsson Foundation and the National Research Council for Medical Sciences, Finland.     

Gel-electrophoretic description of European populations ofTerellia virens (Loew) (Diptera,Tephritidae); implications for its use as an agent for the biological control ofCentaurea spp. (Asteraceae) in North America

Allozyme frequencies of 15 enzyme loci, 14 of which were polymorphic, were used to characterize sevenTerellia virens populations originating from three allopatrically distributedCentaurea species. The two populations whose origins were geographically furthest apart, from Israel (onC. iberica) and from Switzerland (onC. vallesiaca), showed relatively high values of genetic distance from the 5 populations sampled in Austria and Hungary (onC. maculosa) (Nei's D>0.07). The latter five displayed a high degree of genetic similarity. No diagnostic (fixed) allelic differences were observed between these three groups ofT. virens populations, but they could be well characterized by significant differences in allelic frequencies at 9 enzyme loci. Independently of this study, the populations from Switzerland (C. vallesiaca) and eastern Austria (C. maculosa) were selected as potential source populations for future introductions into North America for the biological control of introducedC. maculosa andC. diffusa. Based on the observed genetic differences and results from field experiments on the host specificity of these two potential source populations, it is argued that host specificity screening tests should be conducted separately for local (host plant) populations, as such populations might accept a different set of hosts. Biotype mismatch and the risk of spill-overs to native species could thus possibly be reduced.