Human adenovirus type 5 enhances the thymidine kinase activity of KB cells but does not induce the enzyme in kinase-deficient HeLa (BU25) cells. Vaccinia induces thymidine kinase activity in both KB and HeLa (BU25) cells. Human adenovirus types 2, 4, 7, and 12 also fail to induce the enzyme in HeLa (BU25) cells. Vaccinia replicates equally well in the presence or absence of HATG (hypoxanthine-a...

Variations in the treatment conditions which affect the frequency of BUdR-induced morphogenic lesions in Drosophila melanogaster have been studied. By varying the concentrations of BUdR and FU, or by changing the duration of treatment, it has been demonstrated that increased incorporation of BUdR into DNA results in a concomitant increase in morphogenic lesions. A quantitative analysis of the d...

A pseudorabies virus mutant lacking thymidine kinase activity (TK-) was isolated and characterized. The mutant replicated as well in cell culture as the parental TK+ strain, was not temperature sensitive at 38.5 degrees C, and did not revert to TK+. Two pseudorabies virus field isolates and three commercial modified live virus vaccine strains were compared for TK activity and virulence for the ...

In estrogen-dependent rat adrenocortical carcinomas, thymidine kinase activity decreased during tumor regression following removal of estrogen from the host. The change in the kinase activity could be prevented by estrogen administration but not by the administration of growth hormone or adrenocorticotropic hormone. The alterations in kinase activity were not due to changes in the activity of c...

Plasma thymidine kinase (TK) activity was evaluated as a plasma marker for canine lymphoma and leukemia. A tentative "cut-off" value was set at 6.0 U/l as the upper level of plasma TK based on the mean + 2SD of plasma TK activity in 13 clinically healthy dogs. The levels of plasma TK activity in all of the 20 dogs with lymphoma and leukemia were higher than the cut-off value, whereas those in d...

Kinetic studies of the reactions catalyzed by herpes simplex virus type l-encoded thymidine and thymidylate multifunctional kinase indicate that the addition of substrates (thymidine and ATP*Mg’+, or thymidylate and ATP l Mg2+) to the enzyme is random, while release of the products (thymidylate and ADP*M8+, or thymidine diphosphate and ADP*Mg+) is ordered, with ADP.Mg2+ being released first. Th...

The amount of thymidine-H(3) converted to thymidine-H(3) monophosphate in 30 min formed the basis for assays of thymidine kinase in cell extracts from Tetrahymena pyriformis. The optimal concentration of adenosine triphosphate is lower than that required by other cell types. Thymidine triphosphate does not exercise any feedback control of the enzyme. Other deoxyprimidine nucleotides were tested...