Biophysical investigations on L1210 mouse leukemia cells treated with activated cyclophosphamide metabolites: determination of selective properties of DNA-interstrand and DNA-protein cross-linking mechanisms (alkaline elution and 31P-NMR-spectroscopy) and some aspects of the combination drug and radiotherapy.

Dose-effect relationships have been studied by using L1210 mouse leukemia cells treated with the activated cyclophosphamide derivatives 4-hydroperoxy-cyclophosphamide and 4-sulfido-cyclophosphamide. The combined treatment of the cells with the drugs and irradiation with X-rays indicates synergistic effects, if the irradiation of the cells is performed four to six hours after the drug treatment. DNA-interstrand and DNA-protein cross-linkings have been determined by an alkaline elution procedure. The yield of cross-linkings has been monitoring by either the 3H-14C method or by a 31P-NMR Fourier spectroscopy analysis of the eluted substrates.