BIOTIN 



egg white or casein. The animals fed casein showed an incidence of 

 liver tumours amounting to 77 to 88 %, whilst groups of rats on egg 

 white showed an incidence of tumours ranging from o to 18 %. The 

 injection of biotin did not increase the incidence of tumours, however, 

 and, since symptoms of biotin deficiency developed on the unheated egg 

 white diet but not on the heated diet, it was evident that the protection 

 afforded by egg white against hepatoma formation was independent 

 of any relation between biotin and avidin. 



The biotin content of cancerous tissue ranged from 20 to 100 m/xg. 

 per g. , the lowest value being 5 m^g. per g. for human ovarian adeno- 

 carcinoma and the highest 200 m/x,g. per g. for rat hepatoma.^® These 

 values are within the range recorded for non-cancerous brain, lung, 

 spleen and muscle tissue and much below the values accepted for liver 

 and kidney. 



References to Section 9 



1. P. Gyorgy and C. E. Poling, Proc. Soc. Exp. Biol. Med., 1940, 45, 



773. 



2. E. Nielsen and C. A. Elvehjem, ibid., 1941, 48, 349 ; /• Biol. Chem., 



1942, 144, 405. 



3. G. A. Emerson and J. C. Keresztesy, Proc. Soc. Exp. Biol. Med., 



1942, 51, 358. 



4. J. H. Shaw and P. H. Phillips, ibid., 406. 



5. C. Kennedy and L. S. Palmer, Arch. Biochem., 1945, 7, 9. 

 5a. M. M. Nelson and H. M. Evans, ibid., 1948, 18, 477. 



6. G. A. Emerson and E. Wurtz, Proc. Soc. Exp. Biol. Med., 1945, 69, 



297. 



7. H. R, Skeggs and L. D. Wright, /. Nutrition, 1946, 32, 375. 



8. E. Nielsen and A. Black, ibid., 1944, 28, 203. 



8a. J. W. Wilson, E. H. Leduc and D. H. Winston, ibid., 1949, 38, 73. 

 Sb. L. Mirone and L. R. Cerecedo, Arch. Biochem., 1947, 15, 324. 



9. L. W. McElroy and T. H. Jukes, Proc. Soc. Exp. Biol. Med., 1940, 



45, 296. 



10. S. Ansbacher and M. Landy, ibid., 1941, 48, 3. 



11. T. H. Jukes and F. H. Bird, ibid., 1942, 49, 231. 



12. D. M. Hegsted, R. C. Mills. G. M. Briggs, C. A. Elvehjem and E. B. 



Hart, /. Nutrition, 1942, 23, 175. 



13. W. W. Cravens, E. E. Sebesta, J. G. Halpin and E. B. Hart, Proc. 



Soc. Exp. Biol. Med., 1942, 50, loi ; W. W. Cravens, W. H. 

 McGibbon and E. E. Sebesta, Anat. Rec, 1944, 90, 55 ; J. R. 

 Couch, W. W. Cravens, C. A. Elvehjem and J. G. Halpin, Arch. 

 Biochem., 1949, 21, 77. 



14. L. K. Richardson, A. G. Hogan and O. N. Miller, Univ. Missouri 



Agr. Exp. Stat. Res. Bull., 1942, 343. 



15. J. H. Shaw and P. H. Phillips, J. Nutrition, 1945. 29, 107. 



16. H. Patrick, R. V. Boucher, R. A. Dutcher and H. C. Knandel, Proc. 



Soc. Exp. Biol. Med., 1941, 48, 456; /. Nutrition, 1943, 26, 197. 



430 



