Growth inhibition by methotrexate (MTX) of a cultured mouse mammary carcinoma FM3A line and its mutants deficient in thymidine kinase and thymidylate synthetase was studied under a variety of conditions. In medium containing 10 microM thymidine, the thymidylate synthetase-deficient mutants were slightly more resistant to MTX than the wild-type line and the thymidine kinase-deficient mutant. The...

The pyrimidine deoxyribonucleoside kinase activities were very low in the normal mouse parotid gland, while uridine kinase activity was high. Isoproterenol administration increased uridine, deoxycytidine, and thymidine kinase activities 2-, lo-, and 30-fold, the enzymes reaching maximum activity at 12 to 14, 27, and 30 hours after isoproterenol injection, respectively. DNA synthesis was maximal...

That the regulation of cell division and deoxyribonucleic acid synthesis is subject to some kind of chemical control in higher organisms is widely accepted (2-5). Davidson (2) has suggested that deoxyribonucleic acid synthesis takes place at critical concentrations of the deoxyribonucleoside triphosphates and that these compounds are components of a homeostatic mechanism. There are now at least...

That the regulation of cell division and deoxyribonucleic acid synthesis is subject to some kind of chemical control in higher organisms is widely accepted (2-5). Davidson (2) has suggested that deoxyribonucleic acid synthesis takes place at critical concentrations of the deoxyribonucleoside triphosphates and that these compounds are components of a homeostatic mechanism. There are now at least...

beta-L-5-Iododioxolane uracil was shown to have potent anti-Epstein-Barr virus (EBV) activity (50% effective concentration = 0.03 microM) with low cytotoxicity (50% cytotoxic concentration = 1,000 microM). It exerts its antiviral activity by suppressing replicative EBV DNA and viral protein synthesis. This compound is phosphorylated in cells where the EBV is replicating but not in cells where t...