Effects of nitrogen mustard during the cell cycle of the Ehrlich ascites tumor

Replication-linked histone acetylation in rat liver tissue is sensitive to alkylating agents

The effect of alkylating agents on histone acetyltransferase (EC 2.3.1.48) activity and thymidine incorporation was investigated in benign and malignant proliferating rat liver tissue and compared with the effect in normal non-proliferating rat liver tissue. In both, benign and malignant proliferating tissue, but not in quiescent tissue, the histone acetylation is depressed by alkylating agents and this depression correlates with the inhibition of the thymidine incorporation. This effect suggests that the depression of the replication associated histone acetylation may be an important factor for the antiproliferative activity of alkylating agents.

The effect of cyclophosphamide on the growth and cellular kinetics of a transplantable rat fibrosarcoma

The gross response of a transplantable fibrosarcoma (RIB(5)) in rats treated with a single dose of 10, 50, 100 or 200 mg/kg body weight of cyclophosphamide (CP) is reported. The variation in mitotic and tritiated thymidine ((3)H-TdR) labelling indices after a single dose of 100 mg/kg CP was studied. Examination of chromosome spreads has shown the time course of the visible damage to DNA caused by CP and a transient arrest of cells in G(2) was demonstrated by microdensitometry. The effects of 100 mg/kg body weight CP given in 2 equal doses separated by various time intervals were examined in an attempt to relate tumour response to its altered cellular state at the time of the second dose.