Chemicals such as PB, DDT, EED, sodium deoxycholate, thiobenzamide, orotic acid and SorFAE which enhance the formation of liver tumors or HN, caused a marked decrease in PK activity in Wistar rat liver that persisted for at least 4 weeks, though the decrease caused by EED was not so marked as that caused by other hepatic promoters. Non-promoting agents such as DH, and some chemicals, such as DEXA, testosterone and AB, which enhance the formation of GGT-positive foci in rat livers, but do not enhance the formation of tumors or HN, caused decreases in PK activity in some cases. Any such decreases, however, were only transient and normal levels were restored within 4 weeks. The results suggest that the continuous decrease in PK activity may be a useful marker in screening tests for the promoters of hepatocarcinogenesis.
The effect of a safflower margarine on hepatocarcinogenesis by N, N′-2,7-fluorenylenebisacetamide was compared with that of safflower oil from which the margarine was made. A high-dextrin diet was used as a control for the two high-fat diets. The number of surviving mice in the margarine group at the end of the experiment was significantly lower compared with both the dextrin and the oil groups. A significantly high incidence of hepatic nodules type 2 was observed in the margarine group, whereas most liver tumors in both the dextrin and the safflower oil groups were of HN type 1 (p < 0.05). Hepatocellular carcinomas were induced in some mice in all the groups. However, no statistical difference was found among the three dietary groups. Thus the difference in the types of the hepatic nodules among the three groups was not reflected in the incidence of hepatocellular carcinoma.
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