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R L Dion

Publications and source records attributed to R L Dion.

7 recordsLinked to original sources
PubMed1979

Absolute DNA determinations by flow microfluorometry.

The DNA content of Euglena gracilis and murine leukemic cell line L-1210 were varied by growth under abnormal conditions. DNA measurements by colormetry and by flow microfluorometry were compared and absolute calibration of the flow device was established.

Animals↗
PubMed1978

Effects of chartreusin on cell survival and cell cycle progression.

Chartreusin was lethal to both L1210 and P388 cells in culture with 90% of the cells being killed after a 24-hr exposure to 1.1 and 2.6 microgram/ml, respectively. The lethality of the drug increased in direct proportion to dose and exposure time. Both L1210 and Chinese hamster ovary cells in S phase were more sensitive to the lethality of the drug than were their corresponding non-S-phase cells. L1210 cells were partially synchronized by exposing an asynchronous culture to [methyl-3H]thymidine (20 Ci/mmol) and Colcemid for 3 hr. Synchronous culture of Chinese hamster ovary cells was established by planting mitotic cells. The progression of cells through the cell cycle was studied with flow microfluorometry both in the presence of the drug and after the drug had been washed off. In the presence of chartreusin the progression of mitotic cells into G1 was not affected. The movement of G1 cells into S was slower, and the movement of G2 cells into mitosis was blocked. When the drug was removed, the G2 to M block persisted for at least 4 hr but the progression of G1 cells to S was no longer inhibited.

Animals↗
PubMed1976

Binding of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea to L1210 cell nuclear proteins.

The binding of 1-(2-chloroethyl)-3-(cyclohexyl)-1-nitrosourea (CCNU) to the proteins of the L1210 cell nucleus has been studied using both [cyclohexyl-14C]CCNU and [chloroethyl-14C]CCNU. Most of the bound [cyclohexyl-14C] moiety of CCNU was found to exist in a form that was stable in acid solution but labile and dialyzable in alkaline solution. A small amount of the cyclohexyl moiety was bound to histones in a stable, nondialyzable form. The drug/protein ratio for the H1 histone was about 0.01 to 0.02 mole/mole. No binding of the cyclohexyl group to acidic proteins or of the chloroethyl group to either histones or acidic proteins was observed. Thus, the interaction of CCNU with the proteins of the cell nucleus can be defined in terms of the modification of histones by the cyclohexyl moiety.

Animals↗
PubMedDate not supplied

L-[alphaS, 5S]-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (NSC-163501): a new amino acid antibiotic with the properties of an antagonist of L-glutamine.

L-[alphaS,5S]-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (NSC-163501), an antibiotic elaborated by Streptomyces sviceus, has been shown to be a powerful inhibitor of many mammalian and bacterial reactions involving the transfer of nitrogen from the gamma-carboxamide of L-glutamine. Thus, the utilization of L-glutamine for the synthesis of carbamyl phosphate, L-asparagine, guanosine-5'-monophosphate, cytidine-5'-triphosphate, N-formylglycinamidine ribonucleotide, NAD, glucosamine-6-phosphate, and anthranilic acid is strongly or totally inhibited by a concentration of NSC-163501 of 1 X 10(-3) M. L-Glutamate synthetase of Escherichia coli is only modestly inhibited and 5-phosphoribosylamine synthesis in fetal rat liver is comparatively refractory to inhibition. NSC-163501 treatment of L1210 cells growing in a low L-glutamine culture medium produced arrest in G or early S phase. Of the amino acids tested, only L-glutamine antagonized such growth inhibition.

Animals↗