494 VITAMIN Bi2 



which require B12 to estabHsh themselves at such sites and conceivably 

 produce absorbable substances which are injurious to the host. 



The ability of gastric juice and derivatives of gastric tissue to form an 

 unstable combination with B12 was first demonstrated by Ternberg and 

 Eakin.-" These authors postulated the existence of a specific substance re- 

 sponsible for the B12 binding phenomenon and applied to it the term a'po- 

 erythein. They considered that apoerythein is the intrinsic factor, although 

 their conclusions and hypotheses were unsupported by clinical evidenc^e. 

 It has since been shown by Beerstecher-^ that saliva also contains a sub- 

 stance capable of forming a complex with B12 which renders the vitamin 

 inactive in supporting microbial growth. However, Beerstecher's inference 

 that the intrinsic factor activity (apoerythein) of gastric juice is derived 

 from saliva, which in pernicious anemia patients undergoes inactivation 

 because of lack of hydrochloric acid in the gastric secretion, is completely 

 unsupported by any evidence and must be considered untenable. Saliva 

 has no intrinsic factor activity when tested in patients with pernicious 

 anemia, and, moreover, gastric achlorhydria is of common occurrence in 

 persons who do not have pernicious anemia. 



Lysozyme, derived from egg white, was shown by C. E. Meyer and as- 

 sociates^^ to possess the property of combining with B12, but the complex 

 so formed is no more effective in the treatment of pernicious anemia than 

 the equivalent amount of orally administered free vitamin.-^ The existence 

 of any relationship between binding capacity and intrinsic factor activity, 

 even in the case of stomach tissue derivatives, has been questioned bj^ 

 Prusoff and associates.^* These authors, by chemical fractionation of des- 

 iccated defatted hog stomach, have obtained materials which possess high 

 binding power but are said to have low therapeutic effect as sources of 

 intrinsic factor. However, the reported observations in substantiation of 

 their claim are scanty. It has been the experience of others'- that, with the 

 methods of concentration employed, a parallelism exists l)etween the in- 

 trinsic factor activity of gastric and duodenal preparations and their capac- 

 ity to combine with B12. 



Recently, significant observations on the Bv> binding phenomenon have 

 been reported by Chow and Davis.^^ These authors and their associates-^' " 



20 J. L. Ternberg and R. E. Eakin, ./. Am. Chcm. Soc. 71, 3858 (1949). 



2> E. Beerstecher, Jr., and S. Altselt, J. Biol. Chcm. 189, 31 (1951). 



22 C. E. Meyer, S. II. Epp.stein, F. II. Betlioll, and B. E. Hall, Federation Proc. 9, 

 205 (1950). 



" B. E. Hall, Bnt. Med. J. II, 585 (1950). 



" W. H. Prusoff, G.C. Meacham, R. W. Heinle, and .\. D. Welch, Absfr. 118th Meet- 

 ing, Am. Chem. Soc. Chciago p. 27A (1950). 



26 B. F. Chow and R. L. Davis, Proc. Scient. Sessions 7th Ann. Meeting, Natl. Vitamin 

 Found, p. 17 (1952). 



