The thymidine and leucine methods were examined and used to estimate bacterial production in the Delaware Estuary. During growth experiments that minimized grazing on bacteria, conversion factors for both thymidine and leucine were initially high and then rapidly decreased to values lower than commonly-used factors (2.0 X 10" cells mol-' for thymidine). The low thymidine conversion factors may ...

DnaA protein is the initiator of chromosomal DNA replication in Escherichia coli. We report here our evidence that thymidine transport across cytoplasmic membranes in temperature-sensitive dnaA mutants is greatly decreased at a permissive temperature for growth of the mutants. Complementation analysis with a plasmid containing the wild type dnaA gene and P1 phage-mediated transduction confirmed...

Crystal structures of equine herpesvirus type-4 thymidine kinase (EHV4-TK) in complex with (i). thymidine and ADP, (ii). thymidine and SO(4) and the bisubstrate analogs, (iii). TP(4)A, and (iv). TP(5)A have been solved. Additionally, the structure of herpes simplex virus type-1 thymidine kinase (HSV1-TK) in complex with TP(5)A has been determined. These are the first structures of nucleoside ki...

The rate of tritiated thymidine incorporation into DNA was used to estimate bacterial growth rates in aquatic environments. To be accurate, the calculation of growth rates has to include a factor for the dilution of isotope before incorporation. The validity of an isotope dilution analysis to determine this factor was verified in experiments reported here with cultures of a marine bacterium gro...

To avoid infusing large volumes of fluid while treating patients with the standard thymidine solution (30 g/liter), it may be possible to administer this drug in more concentrated form. At 25 degrees C, thymidine is saturating at a concentration of 52 g/liter of 0.6% NaCl solution, and the thymidine concentration at saturation increases with temperature. Nude mice were infused at 29 degrees C w...

Inhibition of thymidylate synthase (TS) results in a transient "flare" in DNA thymidine salvage pathway activity measurable with FLT ([18F]thymidine)-positron emission tomography (PET). Here we characterize this imaging strategy for potential clinical translation in non-small cell lung cancer (NSCLC). Since pemetrexed acts by inhibiting TS, we defined the kinetics of increases in thymidine salv...

Rich media support the growth of bacteria in the presence of concentrations of sulfonamides and diaminopyrimidines that are highly inhibitory when the organisms are grown on minimal media. Many such rich media can be made more suitable for susceptibility testing by the incorporation of lysed horse blood. Harper and Cawston characterized the active substance, Harper-Cawston factor (HCF), and lat...

Deoxyuridine suppression tests have been performed by two different methods of six normoblastic and eight megaloblastic marrows. A good correlation was obtained between the results by the modified and the original methods. The simplified method was found to be applicable for a clinical purpose to diagnose megaloblastosis in the marrow. Uptake of 3H-deoxyuridine into DNA and effect of various co...

Labelled nuclei were counted in stratified squamous epithelium in mice killed after 24 h intraperitoneal administration of tritiated thymidine to label cells synthesizing deoxyribonucleic acid. Multiple injections produced the same result as an infusion of tritiated thymidine given after 24 h infusion of saline, but infusion of tritiated thymidine alone produced a different result. Thus, cell p...

Cells of the Morris hepatoma 7777 cultured in vitro have elevated levels of cytoplasmic thymidine kinase similar to those found in vivo. The cell-doubling time is slightly less than 24 hr. The addition of 5-fluorouracil to the culture medium (10 micrograms/ml) inhibits cell division, stimulates thymidine kinase production, and results in cell death which increases with time. Treated cells relea...