EFFECT OF VITAMIN B12IN VITRO ON INCORPORATION OF NUCLEIC ACID PRECURSORS BY PERNICIOUS ANEMIA BONE MARROW*

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Abstract
Other investigators reported that the ratios ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) and uracil to thymine were about 2.5 times higher in bone marrow from pernicious anemia (PA) patients before treatment than in marrow from normal subjects. Clinical cures caused these ratios to return to normal. It was suggested that the megaloblast of vitamin B12 deficiency is in a state of "unbalanced growth" that is analogous to filamentous forms of Lactobacillus leichmannii produced by B12 or deoxyribonucleoside starvation. We measured the effect of B12 on incorporation of cytidien-2-C14 and adenine-2-C14 by bone marrow from untreated PA and, to evaluate the specificity of any effect, by nonmegaloblastic, hyperplastic erythroid marrows from hemolytic anemia (HA). Five PA bone marrows were incubatedfor 2 hours in their own plasma diluted with glucose-salts medium, and 1 in glucose-salts medium alone. Added B12 (hydroxycobalamin), 1.7 m[mu]g/ml, stimulated incorporation into DNA bases but not into RNA bases. Addition of this level of B12 to HA marrows, incubated in their own plasma, PA plasma, or glucose-salts medium did not stimulate incorporation into either RNA or DNA.