Kinetic study of membrane 5'-nucleotidase activity in cultured diploid cells]

5'-nucleotidase activity of cultured diplo?d cells was measured using intact suspended cells. This depended on the substrate amount, but did not vary with Mg ++ concentration-Kinetic data were determined using Con. A,a specific inhibitor.     

Demonstration of poliomyelitis virus in homogenates and ureadesoxycholate lysates of cells exhibiting or lacking cytopathogenicity

Zusammenfassung Stark cytolytisch wirkende Urea-Desoxycholatlösung zertört die biologische Aktivität des Poliovirus (Typ I, Mahoney-Stamm)nicht; somit ist dieses Mittel zur Freisetzung infektiösen Materials aus latent oder manifest infizierten Zellkulturen sehr geeignet.     

The inhibitory effect of D-glucosamine on thymidine kinase in chick embryo retinas and HeLa cells

D-Glucosamine markedly inhibits thymidine incorporation into the TCA-insoluble fraction and thymidine kinase activity in HeLa cells. Both the inhibitory effects are also observed in isolated retinas of chick embryos. In this case the inhibitory effects are age-dependent and the magnitude of the responses decreases with embryonic development. In addition the time of exposure to D-glucosamine which is necessary to reveal the inhibitory effect on thymidine kinase increases with the age of the embryos.     

The inhibitory effect of D-glucosamine on thymidine kinase in chick embryo retinas and HeLa cells

Summary D-Glucosamine markedly inhibits thymidine incorporation into the TCA-insoluble fraction and thymidine kinase activity in HeLa cells. Both the inhibitory effects are also observed in isolated retinas of chick embryos. In this case the inhibitory effects are age-dependent and the magnitude of the responses decreases with embryonic development. In addition the time of exposure to D-glucosamine which is necessary to reveal the inhibitory effect on thymidine kinase increases with the age of the embryos.     

The effect of acridities on the synthesis of RNA in isolated nuclei and intact HeLa cells

Zusammenfassung Eine Reihe von Acridinen wurde auf ihre Hemmung der RNS-Synthese intakter Zellen und isolierter Kerne untersucht. In Kernen wurden ähnliche Hemmungsverhältnisse gefunden wie in Bakterien, während in intakten Zellen die Reihenfolge der Stärke der Hemmwirkungen sehr verschieden ist.     

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.     

Creatine phosphate inhibition of heart 5'-nucleotidase appears due to contaminants

Creatine phosphate does not inhibit 5'-nucleotidase preparations from rat, dog or guinea-pig hearts. Previously reported inhibitory effects must have been due to contaminants present in some commercial preparations of creatine phosphate.     

Immunity and cancer: suppressor effect on the cytotoxic activity of lymphoid cells from animals carrying syngeneic tumors]

When it is tested in vitro, the cytotoxic action of lymphocytes from mice bearing a syngeneic tumour (T2) vary with the age of the graft. At a time when it is very low, the lymphoid cells are cultivated for 3 days and then can be fractionated in two subpopulations on a glass bead column: a cytotoxic "non adherent" group of cells and an "adherent" group that inhibits the activity of the first group when it is added to it.     

Early effect of estradiol on ultrastructure of chromatin in the endometrium and hormone-dependent mammary tumors]

After in vivo and in vitro administration of aestradiol, the chromatin of lamb endometrium and of hormone-dependent 7,12-dimethylbenzanthracene Rat mammary tumors is rapidly transformed from a condensed into a diffuse chromatin. A stimulation of 3H leucine incorporation into protein was also observed. These modifications were specific for estrogen receptor ligands and for estrogen responsive tissues. In vitro tamoxifen induced pycnosis. These changes could be used to improve the prediction of hormone dependency of human breast and uterine cancers.     

Poliovirus production in HeLa cells in presence of colchicine

Zusammenfassung Die Vermehrung des Poliovirus in HeLa Zellen war in Gegenwart oder Abwesenheit starker Colchicindosengleich hoch. Die biochemischen Prozesse bei der Spindelbildung sind scheinbar unabhängig von denen der Biosynthese eines RNA-Virus.     

5-hydroxytryptamine-sensitive adenylate cyclase activity in brain synaptosomal membrane preparations]

A serotonine-sensitive adenylate cyclase system has been observed in horse brain membrane preparations. In crude mitochondrial fraction two types of activation sites were characterized, the Ka being = 2 nM and 1 micrometer. In purified synaptosomal membranes, a single adenylate cyclase activation was observed corresponding to the highest apparent affinity (KD = 2nM). This activation site might be related to the high affinity binding site (KD = 2NM) were previously described in the same membrane preparations.     

Compared expression of murine plasmacytoma associated virus in tumor cells and in mouse embryo cells]

A DNA complementary to the viral genome of C-type particles produced by a Mouse myeloma derived cell line (MF2 cell line) was synthesized. This cDNA was used as a probe to study the viral genome expression among the total RNA and the poly (A)-rich RNA extracted from the MF2 and Balb/c embryonic cells. As evidenced by molecular hybridization experiments, the presence of at least one endogenous Balb/c virus in the MF2 virus stocks is suggested. In the productive cells, the viral RNA sequences are expressed in the poly (A)-rich RNA fraction.     

Induction of dolykaryocytes by vesicular stomatitis virus in XC rat cells]

V.S.V. induced polycaryocytes in rat embryonic fibroblasts, transformed by the Prague strain of Sarcoma Rous (XC cells). This fusion is strictly dependent on the expression of the viral genome and is probably due to the incorporation of viral antigens in the cell membrane. The integrity of cellular RNA synthesis is however not required. The fusion is probably due to a membrane structure characteristic of these transformed cells.     

Influence of ionizing radiation on protein production by HeLa cells in culture

Zusammenfassung Bei der Züchtung von HeLa-Krebszellen in tritiumhaltiger Nährlösung während 48 h wurde festgestellt, dass die Mitoserate durch viel kleinere Strahlendosen nachweisbar herabgesetzt wird als die radiochemisch gemessene Rate der Proteinsynthese.