11 CARBOHYDRATES AND LIPIDS 895 



into CO2 and other metabolites in slices of mouse liver or mouse hepatoma 

 C954. The tumor was capable of incorporating isotope into tri- and dicarboxylic 

 acids, glutamate and aspartate. While normal liver readily incorporated isotope 

 from labeled 2-carbon fragments into glucose, the hepatoma failed to carry 

 out this incorporation. Certain quantitative differences were observed in the 

 pattern of labeling of various intermediates when the above components were 

 incubated with slices of liver or hepatoma. The overall conclusion was reached, 

 however, that the citric cycle was operative in the tumor (Brown et al., 1956). 



A series of recent publications has contributed to our knowledge of the meta- 

 bolism of neoplastic tissues. (Emmelot and Bos, 1955, 1955a, 1955b; Emmelot 

 and Bos, 1955a, 1955b; Emmelot et al., 1956). A marked stimulation of fatty 

 acid and cholesterol synthesis from labeled acetate was found after addition of 

 glucose to surviving slices of transplanted mouse tumor. This fatty acid synthesis 

 appeared to be directly related to glycolysis in tumor tissues (Emmelot and Bos, 

 1955b). The ATPase from tumor mitochondria was also capable of destroying 

 the ATP that is required for the formation of acyl coenzyme A and further fatty 

 acid metabolism (Emmelot and Bos, 1955, 1955a). Further evidence was obtained 

 that increased ATPase and DPNase activities may be an inherent feature of tumor 

 mitochondria. This could account for the inhibition of fatty acid oxidation that 

 is present in tumor tissues (Emmelot et al. 1956; Emmelot and Bos, 1956). 



Tumors of adrenal origin utilize acetate- i-^'^C for the synthesis of cholesterol 

 (Smith and Werthessen, 1953). Medes et al. (1956) found that the in vitro conver- 

 sion of labeled acetate to CO2 and cholesterol was essentially the same in normal 

 rat liver, in the precancerous liver of rats fed diets containing 4-dimethylamino- 

 azobenzene, or in the resulting hepatomas. The synthesis of cholesterol from 

 labeled acetate in transplanted mouse tumors was also investigated by Emmelot 

 and Bos (1955a), who found that the total activity incorporated into the choles- 

 terol of the tumors was at least equal to that of liver. A much higher rate of choles- 

 terol synthesis occurred in hepatoma than in ovarian tumor, indicating that all 

 tumors do not behave quantitatively in this respect. 



Berliner et al. (1956) stvidied the chemical transformation of cortisol-4-''*G by 

 normal and leukemic lymphatic tissues of mice. The latter cells converted 10-20% 

 of the Cortisol to six or more metabolites, i.e., cortisone, substances E and U 

 (Reichstein). No conversion was obtained with the normal lymphatic tissues. The 

 significance of this effect of the leukemic tissues upon corticoid metabolism must 

 await further studies. Extracts of ultraviolet irradiated methyl lineolate and methyl 

 linolenate, according to Shuster (1955), inhibited respiratory and glycolytic ac- 

 tivities of Ehrlich ascites tumor cells. Since ascites cells contain unsaturated fatty 

 acids this investigator assumed that a mechanism must be present within the cell 

 with prevents the oxidation of these unsaturated fatty acids, since the fatty acid 

 oxidation products would inhibit cellular activity. 



Literature p. gig 



