Certain characteristics of monosomes produced by carbon tetrachloride

Mechanism of inhibition of hepatic protein synthesis in rats by the carcinogen, methylazoxymethanol acetate

Treatment of rats with the carcinogen, methylazoxymethanol acetate, results in a rapid, marked inhibition of hepatic protein synthesis and disaggregation of polysomes. Studies were undertaken to learn the mechanism by which this carcinogen induces these effects in rat liver. The data show that the inhibition of endogenous protein synthesis is not due to an effect on the high speed supernatant 'factors' but rather at the level of the polysome, and that both free and membrane-bound polysomes are affected. Poly(U)-directed polyphenylalanine synthesis by native ribosomal subunits is greater in preparations isolated from rats treated with carcinogen than it is in controls. Moreover, the native ribosomal subunit fraction from treated livers in response to added rabbit globin mRNA is able to synthesize a protein similar in molecular weight to globin. These studies show that methylazoxymethanol acetate does not induce significant alterations of ribosomal subunits or of initiation factors and suggest that the inhibition of protein synthesis and disaggregation of polysomes may be the results of an alteration of cytoplasmic mRNA, or its association with ribosomes.

Morphological and biochemical studies on the effect of agents with liver protecting properties

The liver protective effect of Aicaphosphate in CC1(4)-induced acute, as well as CC1(4)-and thioacetamide-induced subacute and chronic liver damages is demonstrated. The effect of the protective drugs was studied in the forms of pre-, simultaneous and delayed treatment in acute and chronic liver damages induced by various toxic agents. The degree of liver damage was determined by morphological and biochemical methods, complementary to each other. For the completion of histological studies and morphometry used for the determination of the degree of fibrosis biochemical investigations are performed. In acute liver damage the determination of DNA, protein and lipid contents of the liver tissue and the radioactive aminoacid incorporation rate should be carried out with a simultaneous analysis of the serum enzymes. In chronic liver damage, the measurement of the hydroxyproline and DNA contents of the liver give useful data for the determination of the severity of the lesion and the effect of the protective drugs, respectively.