X. EFFECTS OF DEFICIENCY 89 



(DAB), or butter yellow, demethylation prior to fission of the azo 

 linkage-'*^ • -^^ and methylation of the resulting p-monomethylaminoazoben- 

 zene-"*^ were demonstrated in rats. This observation appeared to support 

 the conclusion of Jacobi and Baumann that DAB was a methyl donor be- 

 cause it prevented the development of renal lesions in young rats on a 

 choline-deficient diet.^^^ Later, Baumann was of the opinion that the pro- 

 tection against renal lesions must have had another explanation-^^ in view 

 of the failure of choline or of choline deficiency to affect the incidence of 

 tumors following DAB administration.^^^-^so Subsequently, it was shown by 

 the feeding of C-"-methyl-labeled DAB that the tagged carbon appeared 

 quickly as carbon dioxide in the expired air and that none was found in the 

 methyls of tissue choline or creatine.-^^ Choline in drinking water did not 

 affect the induction of tumors in rats following the injection of 1,2,5,6- 

 dibenzanthracene-^- or the lesions of bone marrow produced by nitrogen 

 mustards.-^^ 



Using a strain of rats with a high choline requirement,-^"* ■ -" Engel et al. 

 observed that over one-half of chronically deficient animals developed neo- 

 plasms of various types whereas no lesions appeared in control animals.^^®' ^"^ 

 A similar finding was reported l^y Viollier.-^* Aloisi and Bonetti described 

 lesions in the muscles of rats suffering from a prolonged deficiency of methyl 

 donors.-^^ The abnormality differed from the experimental dystrophy due 

 to a deficiency of vitamin E, but it was not possible to separate the direct 

 effect of a lack of methyl from the secondary influence of the hepatic 

 pathology. 



Malignant tumors of the human brain contained elevated levels of free 



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