The investigation of the action of ultrasound on some proteid substances. Part II. The action of ultrasound on diastase

Zusammenfassung Die Ultraschallwirkung auf Diastase wurde an deren Aktivitäts- und pH-Änderung untersucht. Verschieden lang beschallte, 0.5% ige wässerige Diastaselösungen ergaben stufenweises und regelmässiges Absinken der Aktivitäten und pH-Werte.

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Part I: Bull. Soc. chim. Belgrade (in press).     

The toxic effects of certain mutagenic substances on three species of acridids

Summary The toxicities of 4 alkylating agents (EMS, MMS, DES and MNU) were compared using 5th instar males ofLocusta migratoria cinerascens. The substances in order of (decreasing) toxicity were: MMS, MNU, DES and EMS. Treatment of different species, strains, stages and sexes revealed that the toxicity of EMS is not invariant with respect to these factors. Acridids compared to most insects are extremely radiosensitive; this study shows that they are mutagen-sensitive also.     

Investigations on the toxic action ofAmanita phalloides Fr. on the hepatic cell

Riassunto Nel ratto intossicato con estratto diAmanita phalloide le prime alterazioni strutturali dell'epatocita si realizzano a livello del nucleo e del nucleolo con formazioni di «nucleolar caps». Da queste stesse strutture iniziano i fenomeni di regressione delle alterazioni. Le manifestazioni sia del danno che della sua regressione a livello citoplasmatico risultano essere successive a quelle nucleari. Il comportamento del DNA e di alcuni enzimi del tessuto epatico è risultato nel complesso coerente con le alterazioni morfologiche. In rapporto con la dose usata queste alterazioni risultano reversibili poichè nelle cellule colpite entro 12 h cominciano i fenomeni di ristrutturazione.     

The mechanism of action of glyceraldehyde-3-phosphate dehydrogenase

Zusammenfassung Zur Erforschung des Wirkungsmechanismus einer komplexen Enzymreaktion vom Typus der GAPD können die mit der Wirkung dieses Enzyms verknüpften hypokatalytischen Vorgänge gewisse Anhaltspunkte geben. Als hypokatalytische Vorgänge werden die Reaktionen bezeichnet, die durch einen Teil des natürlichen aktiven Enzyms GAPD auf unspezifische Substrate ausgeübt werden. Auf Grund der Analyse einer solchen Reaktion, d. h. der Hydrolyse desp-NPA durch GAPD, wird die natürliche Funktion des Enzyms diskutiert.Während der Hydrolyse desp-NPA wird die-Aminogruppe eines Lysinrestes der GAPD spezifisch acetyliert, die möglicherweise einen Teil des Bindungsortes der GAPD bildet.Auf Grund unserer Experimente und mit Hinblick auf frühere Publikationen anderer Forscher wird ein mögliches Modell des aktiven Bereichs der GAPD vorgeschlagen.     

Supercontraction of conifer chromosomes under the action of alkylating nitrosocompounds

Summary After treatment of seeds of the Norway spruce and of the Scotch pine with alkylating nitrosocompounds, an extremely strong contraction effect on mitotic metaphase chromosomes was observed in the first cell-cycles of the posttreatment period.     

The fasciolicidal activity of a halogenated benzenesulfonanilide.

Halogenated benzenesulfonanilides have potent fasciolicidal activity. The efficacy of 1 such compound in mice, sheep, and cattle is reported.     

Inhibition of phosphatase by open-chain nucleoside analogues in insects

(S)-9-(2,3-dihydroxypropyl) adenine (DHPA), D-eritadenine and some other open-chain nucleoside analogues, which exhibit adverse biological effects in microorganisms, plants and animals, cause pronounced inhibition of intestinal phosphatases in the hemipteran insect Pyrrhocoris apterus. The rate of p-nitrophenylphosphate hydrolysis by homogenates from intestinal epithelium and Malpighian tubules was inhibited up to 94% by 2-10 millimolar concentrations of these drugs. This effect is stronger than that of sodium fluoride, which is recognized as a common inhibitor of phosphatase. We conclude that inhibition of phosphatase activity in the digestive and excretory organs may be responsible for the previously reported massive excretion of phosphorylated derivatives of the nucleoside analogues after their oral administration to insects.     

Inhibition of the NADP-linked glutamate dehydrogenase from Trypanosoma cruzi by silver nitrate.

The purified NADP-linked glutamate dehydrogenase from Trypanosoma cruzi was strongly inhibited by silver nitrate. The inhibition was reversed by reduced glutathione, and was modified by the presence of the substrates during preincubation of the enzyme with the inhibitor.     

Inhibition of testicular androgenesis by urinary gonadotropin-inhibiting substances in rats

The effect of urinary gonadotropin-inhibiting substances (GIS) on the androgen synthesis in rat testes was studied in vitro and in vivo. GIS, which was added to the incubation medium containing tesased testicular tissues and injected into rats for 2 days, showed a suppressive effect on the formation of androstenedione from pregnenolone in the testis.