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Title: Effect of tetrahydrouridine on metabolism and transport of 1-beta-D-arabinofuranosylcytosine in human cells. Author: Riva C, Barra Y, Carcassonne Y, Cano JP, Rustum Y. Journal: Chemotherapy; 1992; 38(5):358-66. PubMed ID: 1286578. Abstract: Deamination of cytosine arabinoside (ara-C) by cytidine deaminase is the main mode of inactivation of this drug which can be responsible for ara-C resistance. The present study was undertaken to determine the effect of tetrahydrouridine (THU; a potent inhibitor of cytidine deaminase) on ara-C transport and metabolism in human cells. A rapid transport of ara-C into freshly isolated hepatocytes and an increased intracellular accumulation of the unchanged drug were observed in the presence of 50 micrograms/ml THU. THU inhibited the intracellular deamination of ara-C by 80% and slowed elimination of the compound extracellularly. The intracellular ara-C concentrations achieved after incubation with 1 micrograms/ml ara-C plus 50 micrograms/ml THU are similar to those attained with ara-C (10 micrograms/ml) alone. Treatment of leukemic K562 cells with the combination of THU (50 micrograms/ml) and ara-C (1 micrograms/ml) led to an augmentation of intracellular ara-C triphosphate formation up to twofold.[Abstract] [Full Text] [Related] [New Search]