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Biomedical subjects

U Bachrach

Publications and source records attributed to U Bachrach.

At least 73 records · Page 4Linked to original sources
PubMed1980

Increase in S-adenosyl-L-methionine decarboxylase activity during the transformation of chick embroy fibroblasts by Rous sarcoma virus.

The increase in S-adenosyl-L-methionine decarboxylase activity in chick embryo fibroblasts after infection with Rous sarcoma virus has been studied. It has been shown that enzyme levels in transformed cells were two or three times higher than those of the non-infected controls. The activity of this enzyme was not elevated in chick embryo fibroblasts infected with a temperature sensitive mutant of Rous sarcoma virus (RSV-T5) at 42 degrees C, the non-permissive temperature. When the temperature of these infected cultures was shifted from 42 degrees C to 37 degrees C a two- or three-fold increase in decarboxlase activity was detected after 10 to 12 h. The half-live of S-adenosyl-L-methionine decarboxylase was practically identical in normal and RSV-transformed fibroblasts.

Adenosylmethionine Decarboxylase↗
PubMed1980

Metabolism of polyamines by cultured glioma cells. Effect of asparagine on gamma-aminobutyric acid concentrations.

The activity of ornithine decarboxylase (EC 4.1.1.17) increased in confluent cultures of glioma C6BU-1 cells 3 h after adding a complete serum-containing medium, and was maximal 5 h later. The activity of S-adenoxyl-L-methionine decarboxylase (EC 4.1.1.50) increased soon after addition of the complete medium to the cells, and reached its peak after 11 h. The activity of diamine oxidase (EC 1.4.3.6) also increased soon after adding complete medium and was maximal 8h later, when the activity of ornithine decarboxylase reached its peak. The increase in the activity of S-adenosyl-L-methionine decarboxylase was accompanied by changes in cellular spermidine and spermine concentrations, whereas the increase in the activity of diamine oxidase was followed by the accumulation of gamma-aminobutyric acid, which was detected both in the cells and in the medium. Asparagine enhanced the utilization of radioactive putrescine by glioma cells suspended in buffered-salt/glucose solution and increased intracellular and extracellular gamma-aminobutyric acid concentrations. Radioactive putrescine was converted into spermidine and spermine by glioma cells after addition of a serum-containing medium, but not after adding buffered--salt/glucose solutions, in the presence or absence of asparagine. The kinetics of ornithine decarboxylase 'induction' and the half-life of the enzyme differed in cells incubated with buffered asparagine solutions and serum-containing media.

Amine Oxidase (Copper-Containing)↗
PubMed1980

Studies on phage internal proteins. VI. Interaction of bacteriophage T4 internal proteins with T4 DNA in vivo and in vitro.

Internal proteins are basic proteins bound to the DNA of T4 coliphage. Centrifugation in sucrose gradients was employed to isolate DNA-internal proteins complexes formed in vitro. Polyacrylamide gel electrophoresis of radioactive internal proteins in the presence of sodium dodecyl sulfate followed by autoradiography of the gels was used to identify the DNA-bound proteins and to determine their respective abundance in these complexes as well as in the bacteriophage head. The internal proteins were found to bind to the phage DNA (in vitro experiments) at the same ratio as that of internal proteins associated with the viral DNA within the phage head (in vivo binding).

Centrifugation, Density Gradient↗
PubMed1979

Polyamines and cellular adenosine 3' :5'-cyclic monophosphate.

The effect of polyamines on the cellular concentrations of cyclic AMP was studied. It was shown that 1 microM-spermine caused a decrease in cyclic AMP in chick-embryo heart cells, chick-embryo fibroblasts, neuroblastoma, glioma and neuroblastoma-glioma hybrid cells, grown in culture. A similar decrease was observed when polyamines were added to cells in the presence of a phosphodiesterase inhibitor or after stimulating the cells with various hormones. Noradrenaline was used in cultures of heart cells, prostaglandin E1 and adenosine for neuroblastoma and neuroblastoma-glioma hybrids, whereas isoproterenol was used for the stimulation of glioma cells. Polyamines at higher concentrations were either without effect or caused a slight increase in cyclic AMP. Spermidine (10 microM) also caused a decrease in cellular cyclic AMP, as did 0.1 microM-putrescine. It is suggested that the effect of polyamines on cellular cyclic AMP may be explained by the effect of these polycations on the activity of cellular phosphodiesterase.

Adenosine↗
PubMed1977

Effect of hydrolyzed formaldehyde-treated RNA on neoplastic and normal human cells.

Alkaline hydrolysate of dialyzed formaldehyde-treated RNA, in which 39% of purine nucleotides are modified to methylene bis derivatives (R-CH2-R'), displays cytotoxic activity toward cultured human tumor cells. The alkaline hydrolysate of dialyzed formaldehyde-treated RNA is substantially less toxic to normal human embryonic cells. There is a correlation between the cytotoxic effect and cell growth rate, which has been traced by quantitative tests.

Antineoplastic Agents↗