The effect of 2',6'-dimethyl-N(4')-benzyl-N(4')- [desmethyl]rifampicin on viral transformation induced by two unrelated oncogenic viruses was compared. Transformation of Balb/3T3 cells by the small, DNA-containing papova virus simian virus 40 was completely normal under conditions where transformation by the large, RNA-containing oncornavirus murine sarcoma virus was inhibited more than 150-fol...

The frequency of sister chromatid exchange (SCE) has been followed sequentially after the addition of SV40 to human diploid fibroblast cultures. The SCE frequency was nearly the same in uninfected controls and in infected cultures before they became tumor antigen positive. When cells exhibited tumor antigen, the SCE frequency increased over a wide range, and changes in chromosome number and str...

We investigate Room squares and subsquares. All terminology is as in [6] and [7], and we will assume the reader is familiar with the definitions contained therein. (These include group-divisible designs, transverial designs, and frames.) We will refer to an incomplete Room square of side s missing a subsquare of side t as an (s, t)-incompZefe Room square. It is known that for any odd t, there i...