To the Editor: In their article, Shipkova et al. (1 ) present evidence to indicate that the concentration of erythrocyte thioguanine nucleotides (TGNs) measured by the method of Lennard (2 ) differ considerably from those measured by the method of Dervieux and Boulieu (3 ). The assay method studied by Shipkova et al. was superseded over a decade ago for studies of thiopurine metabolism (4 ). Ho...

A series of phosphinegold(I) thionucleobase analogues, [R(3)PAu(SR(x))] (R = Et, Ph or chexyl; HSR(1) = 2-mercaptobenzoic acid, HSR(2) = 2-thiouracil, HSR(3) = 6-mercaptopurine and HSR(4) = 6-thioguanine) have been examined for their in vitro cytotoxicity in L1210 murine leukemia cells in culture. The range of ID(50) values (continuous 48 h exposure) for the complexes is 0.041 - 0.131 muM. The ...