Studies on the Biochemical Defect of Pernicious Anemia. I. In Vitro Observations on Oxygen Consumption, Heme Synthesis and Deoxyribonucleic Acid Synthesis by Pernicious Anemia Bone Marrow12

Abstract

In microbiological systems, folic acid and vitamin B12 appear to be important in the synthesis of purines and pyrimidines, in the synthesis of methyl groups, and possibly in the synthesis of deoxyribose (1-3). Studies at the clinical level, summarized by Mueller and Will (4), indicate that similar biochemical processes may be involved in patients with pernicious anemia (P. A.). Because such studies on patients are difficult to carry out and interpret, precise methods of in vitro assessment of the biochemical activity of P. A. marrow cells are needed.Direct studies on P. A. marrow have been confined, for the most part, to observations of morphologic changes and cell counts in tissue culture (5)(6)(7)(8)(9)(10)(11)(12). In attempting to avoid the difficulties inherent in evaluating these changes in tissue culture and in an effort to secure more direct biochemical information, P. A. marrow has been studied in our laboratory by the following techniques: 1) oxygen consumption, 2) heme synthesis as measured by the rate of incorporation of C14-glycine into heme, and 3) deoxyribonucleic acid (DNA) synthesis by measurement of the rate of incorporation of C14-formate into thymine.With these techniques, which permit measurements of biochemical activity over short periods of time and with small amounts of bone marrow, we have attempted to answer the following questions: 1) Does vitamin B12 have a direct effect on P. A. marrow cells? 2) Why has the liquid culture-vaccine vial technique failed to demonstrate an

Deranged DNA Synthesis by Bone Marrow from Vitamin B12‐Deficient Humans*

“…Studies with human bone marrow from BIZ-deficient patients have likewise failed to consistently demonstrate a direct role for the vitamin in DNA synthesis. Thomas and Lochte (1958) reported that B,, enhanced the rate of incorporation of 14C formate into DNA in bone marrow cultures from patients with pernicious anaemia. However, they did not run a control with added PGA instead of Biz.…”

High plasma folate is negatively associated with leukocyte telomere length in Framingham Offspring cohort

“…In a lesion model of central nervous system injury, administration of folic acid resulted in neuronal regeneration, but use of higher concentrations folic acid had a negative influence on neuronal regeneration [42]. Deficiency of folate impairs DNA synthesis and results in anemia [43, 44]. At the other end of the spectrum, presence of unmetabolized folic acid in plasma that is indicative of high folic acid intake is associated with higher incidence of anemia in humans [45], which suggests impairment of DNA synthesis.…”

Pyrimidine Metabolism in Man. Iii. Studies on Leukocytes and Erythrocytes in Pernicious Anemia*†

“…In this way B12 40 cX might be concerned with the synthesis of thymine, n which has been reported to produce a partial re-30 I-mission in pernicious anemia when given in large > oral doses (14). In marrow cells from pernicious 20 0 anemia studied in vitro the addition of B.2 to the plasma suspension has been shown to stimulate 0 the incorporation of C14-formate into thymine,°p resumably an indication of increased synthesis of DNA (4). There is evidence that as a second function, B12 may be concerned with the synthesis of deoxyriboside or deoxyribotide derivatives of purine and pyrimidine bases (2).…”

“…In such a capacity, B12 might be concerned with the synthesis of the methyl group of thymine (3) or of the pentose moiety of thymidylic and deoxycytidylic acids. In vitro studies of pernicous anemia marrow have indicated a direct stimulation by B12 of the incorporation of C14-formate into thymine (4).…”