Inhibitory effect of 5-bromo-6-azauracil on growth and cell division ofSaccharomyces cerevisiae

Summary The most marked effect of 5-bromo-6-azauracil (BrAzU) on yeast cells is to cause cell lysis. The inhibition of the lytic process is delayed and this delay coincides in time with the capacity of preformed pyrimidines to reverse the effect of BrAzU.     

Lack of effect of dihydroergotamine on endothelial and smooth muscle cell proliferation and endothelial cell prostanoid production

The most important effect of dihydroergotamine is venoconstriction, but certain metabolic effects and changes in vessel prostanoid activity have also been suggested. In this study endothelial cell production of 6-keto PGF1 alpha and TxB2 was quantitated in vitro. No evidence of altered prostanoid production was noted after incubation with dihydroergotamine (exposure ranging from 5 x 10(-3) to 5 x 10(-7) g/l). Similarly, no effect of dihydroergotamine on the growth rates of endothelial cells or smooth muscle cells in vitro was documented.     

Lack of effect of dihydroergotamine on endothelial and smooth muscle cell proliferation and endothelial cell prostanoid production

Summary The most important effect of dihydroergotamine is venoconstriction, but certain metabolic effects and changes in vessel prostanoid activity have also been suggested. In this study endothelial cell production of 6-keto PGF₁ and TxB₂ was quantitated in vitro. No evidence of altered prostanoid production was noted after incubation with dihydroergotamine (exposure ranging from 5×10^–3 to 5×10^–7 g/l). Similarly, no effect of dihydroergotamine on the growth rates of endothelial cells or smooth muscle cells in vitro was documented.     

Dimethyl sulphoxide effect on division cells

Resumen Dimetil sulfóxido, potente antimetabolito, a distintas concentraciones altera significativamente la cinética de poblaciones meristemáticas radicales deAllium cepa L., produciendo un cuatro de alteraciones morfológicas y figuras mitóticas atípicas.     

Inhibitory effect of aromatic diamidines on trypsin and enterokinase

Zusammenfassung Aromatische Diamidinoverbindungen sind hochwirksame Hemmstoffe des Trypsins. 2,2-Dibromopropamidin, die stärkste der hier untersuchten Verbindungen, besitzt gegenüber der BANA-Hydrolyse eine Inhibitions-Konstante von 7.6×10^–7 M. Amicarbalid und M & B 4596 sind gute Hemmstoffe der Enterokinase, doch erreichen sie die Wirkung derp-Amidinophenylbrenztraubensäure nicht.     

Inhibitory effect of cytembena (sodium-cis-beta-methoxybenzoyl-beta-bromoacrylate) on the cell kinetics of HeLa cells in culture

The inhibiting effect of Cytembena on HeLa cell kinetics has been demonstrated and analyzed. The percentage of cycling cells decreases, according to the concentration, between 7.5 and 2.5 x 10(-5) M. Estimation of DNA by cell flow cytophotometry shows an important shift in the distribution of cycling cells with a relative decrease of G1 cells and a very important accumulation of G2 cells. According to our experimental conditions, the blocking up in G2 is irreversible only at 7.5 x 10(-5) M.     

Inhibitory effect of flavonoids on DNA-dependent DNA and RNA polymerases

Flavonoids, (-)-epigallocatechin (1), myricetin (2) and quercetin (3), were investigated for inhibitory effects on E. coli DNA polymerase I and T7 bacteriophage RNA polymerase. In both DNA and RNA synthesis, 1 and 3 inhibited enzyme reactions by non-competitive and mixed type inhibition respectively, with regard to template DNAs. Myricetin (2) inhibited DNA and RNA polymerase reactions by mixed type and competitive type inhibition, respectively, with template DNAs. It was suggested that 2 interacts with covalently closed circular DNA.     

Inhibitory effect of flavonoids on DNA-dependent DNA and RNA polymerases

Summary Flavonoids, (–)-epigallocatechin (1), myricetin (2) and quercetin (3), were investigated for inhibitory effects onE. coli DNA polymerase I and T7 bacteriophage RNA polymerase. In both DNA and RNA synthesis,1 and3 inhibited enzyme reactions by non-competitive and mixed type inhibition respecitively, with regard to template DNAs. Myricetin (2) inhibited DNA and RNA polymerase reactions by mixed type and competitive type inhibition, respectively, with template DNAs. It was suggested that2 interacts with covalently closed/circular DNA.     

Inhibitory effect of some heteropolyanions on potato virus X

Summary Heteropolyanions like 12-tungstozincic acid (i.i.), potassium 13-vanadomanganate (i.v.), potassium 13-vanadonickelate (i.v.) and sodium tungstoborate produced an inhibitory effect on potato virus X. Amongst these, tungstozincic acid was found to be the most potent.The authors are thankful to Prof. R. P. Rastogi, Head of the Chemistry Department, University of Gorakhpur for providing necessary facilities. The financial support by Council of Science and Technology, U.P., Lucknow is gratefully acknowledged.     

Inhibitory effect of cytokinins on PHA-induced human lymphocyte stimulation

Summary The inhibitory effect of various purine derivatives on PHA-induced human lymphocyte blast formation was studied. Two nucleoside cytokinins, N⁶-benzyladenosine and N⁶-isopentenyladenosine, inhibited blast formation at concentrations as low as 10^–6 M. However, the other cytokinins, which lacked the ribosyl residue at N⁹ position, had to be at the higher molar concentration of 10^–4 before they could induce the same inhibitory effect.     

Inhibitory effect of cytokinins on PHA-induced human lymphocyte stimulation.

The inhibitory effect of various purine derivatives on PHA-induced human lymphocyte blast formation was studied. Two nucleoside cytokinins, N6-benzyladenosine and N6-isopentenyladenosine, inhibited blast formation at concentrations as low as 10(-6) M. However, the other cytokinins, which lacked the ribosyl residue at N9 position, had to be at the higher molar concentration of 10(-4) before they could induce the same inhibitory effect.     

Inhibitory effect of bile acids on renin angiotensinogen reaction system

Zusammenfassung Die Wirkung verschiedener synthetischer Derivate der Gallensäure wurden auf die Reninaktivität in Form des Angiotensin in vitro untersucht und es wird darauf hingewiesen, dass die 7-Desoxyform der Gallensäuren für die Renininhibition wesentlich ist.

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The authors wish to thank Dr.T. Hoshita of Department of Biochemistry, Hiroshima University, for his kind supply of cholic acid.     

Inhibitory effect of tiaramide on ADP-induced aggregation in rabbit platelets

Summary Tiaramide in 10^–4 or 10^–5 M depressed the ADP-induced aggregation of rabbit platelets using the turbidimetric method. In modified Chandler's loop method, tiaramide in the same concentration accelerated the restoration of the time course of disaggregation.Acknowledgment. We are very grateful to Dr T. Takashima, Fujisawa Pharmaceutical Co. Ltd, for gifts of the pure tiaramide.T. Aikawa, T. Oishi, M. Goto and O. Tamura are students of Fukushima Medical College.     

The growth of cell membranes during synchronized cell division ofSaccharomyces cerevisiae

Riassunto Cellule diSaccharomyces cerevisiae venivano coltivate in brodo centenentel-Leucina-³H o³²PO ₄ ^– raccolte in fase log e quindi coltivate in modo sincrono in nuovo terreno privo di radioisotopi. Le cellule e le gemme venivano separate per centrifugazione su gradiente di saccarosio, quindi si isolavano le membrane. La radioattività specifica nelle membrane purificate risultava circa il 50% di quella presente inizialmente nelle cellule usate per la coltura sincronizzata.     

Inhibition of cell division in mammalian cell cultures by hypertonic medium

Résumé L'arrêt de la métaphase se produit dans les cellules de HeLa S-3 au contact d'un milieu de tonicité accrue (>165 mM). L'accumulation optimale intervient à 277 mM lorsque du NaCl a été utilisé pour augmenter l'influence du milieu. Les effets de l'usage d'autres sels et d'autres types de cellules sont décrits. La dilution du milieu à 165 mM donne lieu à un arrêt synchrone du processus de la mitose dans les cellules et assure la conservation d'un bon synchronisme au cours de la division cellulaire suivante.     

Inhibition of DNA synthesis and cell division by actinomycin D

Zusammenfassung Nach in-vitro-Kultur oder Verwundung in vivo der Froschlinsen wird zuerst meistens, im Epithel, eine intensive DNS-Synthese gefunden auf die später zahlreiche Kernteilungsfiguren folgen. Nach Behandlung mit Actinomycin D werden diese Reaktionen stark gehemmt. Autoradiographische Untersuchungen mit dem DNS-Vorläufer H-3-Thymidin und dem RNS-Vorläufer H-3 Uridin erlauben den Schluss, dass die DNS-Synthese (und damit Zellteilung) von einer früheren RNS-Synthese abhängt.

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This work was supported in part by Public Health Service Grant No. NB-05425-01 and also by institutional grant 71D from the American Cancer Society.

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Supported by U.S. National Science Foundation grant No. GE-6534 5/410-0056.     

Inhibitory effect of beta-hydroxyglutamic acid on a molluscan giant neurone.

We found a spontaneously firing neurone, inhibited by beta-hydroxy(erythro)-L-glutamic acid, identified in the subesophageal ganglia of an African giant snail (Achatina fulica Férussac), although this neurone is not sensitive to L-glutamic acid. We suggest that beta-hydroxy(erythro)-L-glutamic acid may be a putative inhibitory synaptic transmitter of the identified molluscan neurone.     

The relationship between cell division and cell specialization in the mouse intestinal epithelium

Zusammenfassung Der Zusammenhang zwischen der Teilung von Ursprungszellen und der Differenzierung ihrer Tochterzellen wurde anhand von Epithelzellen des Duodenums weisser Mäuser untersucht. Um den Zustand des «steady state» zu erhalten, finden die folgenden Arten von Teilung der Ursprungszellen statt: 1) zwei neue Ursprungszellen; 2) zwei differenzierte Tochterzellen; oder 3) eine neue Ursprungszelle und eine differenzierte Tochterzelle.

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I wish to particularly thank Mrs. Z.Trirogoff for her skilled technical assistance. This work was supported in part by Research Grant No. GM 14749-01, National Institutes of Health and General Research Support Funds, UCLA School of Medicine. Portions of this work were presented before the American Association of Anatomists, Anat. Rec.157, 333 (1967).