[Metabolism of nucleic acids in normal, regenerating and neoplastic tissues of the liver].

Under study was the kinetic growth of three hepatomas-22A, 60 and 46, characterized by a various degree of differentiation. There was found a correlation between the degree of differentiation and parameters of the hepatomas growth. For the hepatomas a correlation between the DNA content and rate of growth was observed, for hepatoma 46 a value of the DNA content proved to be near to that of normal liver. Moreover, in a regenerating liver the DNA content is the same as normal, that indicates the difference between normal and neoplastic actively proliferating tissues. The processes of DNA synthesis, studied by thymidine-C14 incorporation, showed a linear correlation with the rate of growth in regenerating, normal and neoplastic tissues. The ratio RNA/DNA in tumors is regularly decreased with respect to normal liver (a linear correlation between RNA/DNA and the maximum rate of growth). In a regenerating liver the ratio is high. Variations in the ratio RNA/DNA reflect changes in the functional activity and related disorders in the metabolism of nucleic acids in hepatomas. There was found a suppressed DNA decomposition in autolysis of homogenates from hepatoma tissues. It is essential to note that in a minimum deviated hepatoma some inhibition of the DNA decomposition is the only observed disorder in the nucleic acids metabolism. Spin-labelled DNA preparations of tissues under study were obtained. The presence of structural differences between separate DNA samples has been demonstrated.