424 VITAMIN Bi2 



especially on diets which supplied borderline quantities of precursors of 

 choline. Hall and DrilP^ found that either choline or crude liver extract 

 prevented fatty infiltration and fibrosis in the livers of rats fed a diet 

 containing 16% casein and 59% fat. The effects of the liver extract could 

 not be attributed to its choline content. 



Another reason for a connection between vitamin B12 and liver function 

 was postulated by Stern and coworkers.-^ These workers, noting the rela- 

 tionship of vitamin B12 to the formation of desoxyribosides, investigated 

 the effect of vitamin B12 upon nucleic acids in the rat as measured by the 

 concentration of basophilia in the liver tissue. It was found that rats which 

 were deficient in vitamin B12 showed few or no liver basophilia whereas 

 those which received vitamin B12 or liver grew well and had a considerable 

 number of cytoplasmic basophilia in their liver cells. This suggested to 

 Popper and coworkers^^ that vitamin B12 might alleviate the hepatic injury 

 due to carbon tetrachloride poisoning, since ribonucleic acid disappears from 

 the cells of the liver in the early stages of carbon tetrachloride intoxication. 

 Administration of 15 7 of vitamin B12 per 100 g. of body weight to rats 

 preceding a toxic dose of 0.033 ml. of carbon tetrachloride per 100 g. in- 

 hibited the development of histologic changes, the deposition of lipids, 

 and the retention of bromosulfalein. Gyorgy and Rose-^ also found that 

 vitamin B12 had a lipotropic effect in rats when 0.5 7 was fed daily. 



Confirmatory evidence of the preventive effects of vitamin B12 against 

 carbon tetrachloride poisoning was given by Mushett,-^ who found pro- 

 tection against a single dose, but when both substances were given daily 

 for a period of three weeks, the vitamin failed to prevent the hepatic 

 changes. Hove and Hardin^'' found that either vitamin B12 or vitamin E 

 protected against carbon tetrachloride toxicity. The requirement of vita- 

 min B12 for protection was considerably higher than for growth. 



In studies with dogs^^ a basal diet was used containing 30% extracted 

 peanut meal, 39.5% sucrose, 6% washed casein, 19% lard, 0.1% cystine, 

 vitamins (except B12), and minerals, plus choline 0.05%. Severe edema 

 and ascites were developed which could be prevented by adding a concen- 

 trate of vitamin B12 or by raising the level of choline to 0.30 %. Cirrhosis 

 was noted in several dogs on the low-choline diet without vitamin B12. 



26 C. A. Hall and V. A. Drill, Proc. Soc. Exptl. Biol. Med. 69, 3 (1948). 



26 J. R. Stern, M. W. Taylor, and W. C. Russell, Proc. Soc. Exptl. Biol. Med. 70, 551 



(1949). 

 " H. Popper, D. Koch-Weter, and P. B. Szanto, Proc. Soc. Exptl. Biol. Med. 71, 



688 (1949). 

 2» P. Gyorgy and C. S. Rose, Proc. Soc. Exptl. Biol. Med. 73. 372 (1950). 

 " C. W. Mushett, Federation Proc. 9, 339 (1950). 



30 E. L. Hove and J. O. Hardin, Proc. Soc. Exptl. Biol. Med. 77, 502 (1951). 



31 A. E. Schaefer, D. H. Copeland, and W. D. Salmon, J. Nutrition 43, 201 (1951). 



