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JAMA. 1948;138(8):595. doi:10.1001/jama.1948.02900080053011.
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Shorb1 in 1947 reported finding in refined liver extracts a factor required by Lactobacillus lactis Dorner (L. L. D. factor) which was present in an almost linear relationship to the unit potency of the extracts used in the treatment of pernicious anemia. Rickes2 and his associates have isolated from liver a crystalline compound, vitamin B12, and Shorb, who assayed its potency value for L. lactis Dorner, considered it to be either wholly or partially responsible for the L. lactis Dorner growth activity observed for liver extracts. West3 reported a positive hematologic response in 3 patients with pernicious anemia following the intramuscular administration of vitamin B12 in single doses of 3, 6 and 150 micrograms. Spies,4 in 1948, reported on the use of crystalline vitamin B12 in the treatment of addisonian pernicious anemia in 2 cases, nutritional macrocytic anemia in 2 cases and nontropical


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