502 VITAMIN Bi2 



before B12 had been isolated and identified as extrinsic factor, von 

 Bonsdorff^^ had shown that for anemia to occur in fish tapeworm infestation 

 it was necessary that the worm be lodged in the upper portion of the small 

 intestine. He believed that the worm interfered with the interaction of 

 intrinsic and extrinsic factors, and he made the shrewd observation: "Much 

 confusion in the discussions could, I believe, be avoided if the ability of 

 the worm to produce pernicious anemia was consistently kept separate 

 from its other toxic properties." Later studies have established the validity 

 of this statement, since von Bonsdorff and his colleagues^^' ^^ have dem- 

 onstrated the presence of B12 in considerable amounts in dried fish tapeworm. 

 They obtained therapeutic responses in addisonian pernicious anemia pa- 

 tients who were given the dried worm as a source of extrinsic factor (B12) 

 in combination with normal gastric juice containing intrinsic factor, as well 

 as in patients with fish tapeworm anemia who received the dried worm 

 without a source of intrinsic factor. These observations are interpreted as 

 indicating that the worm, if located sufficiently high in the intestine, may 

 utilize the naturally available B12 even in the presence of intrinsic factor 

 and so lead to B12 deficiency in the host. If B12 is administered orally in 

 amounts greater than the worm can assimilate, the deficiency will be over- 

 come. 



5. Gastrectomy 



Megaloblastic anemia following total gastrectomy may be attributed, 

 at least in part, to removal of the source of supply of intrinsic factor. How- 

 ever, other digestive disturbances affecting nutrition appear to be of im- 

 portance in some cases. Thus, some patients who develop macrocj'^tic 

 anemia after removal of the stomach can be maintained in satisfactory 

 remission for long periods by the parenteral administration of purified 

 liver extract or B12 (author's cases) whereas others fail to regain fully nor- 

 mal hematologic values or exhibit a fall in values after good initial responses. 

 There is evidence that deficiency of PGA, not relieved by B12, may be pres- 

 ent after gastrectomy.^^ 



6. Intestinal Abnormalities 



In megaloblastic anemia associated Avith intestinal strictures or anas- 

 tomoses, the therapeutic response to B12 has been variable, and it appears 

 that PGA rather than B12 deficiency may be largely responsible for the 

 development of anemia in these cases. Unglcy^^ reported two such cases 



S'' B. von Bonsdorff, Blood 3, 91 (1948). 



«6 B. von Bonsdorff and R. Gordin, Acta Med. Scand. 140, Suppl. 259, 112 (1951). 



66 B. von Bonsdorff and R. Gordin, Acta Med. Scand. 142, Suppl. 268, 2S3 (1952). 



•' N. S. Conway and H. Conway, Brit. Med. J. I, 158 (1951). 



68 C. C. Ungley, Proc. Roy. Soc. Med. 43, 537 (1950). 



