British Journal of Haematology, 1976,33, 152.

Correspondence VITAMIN B

ANALOGUES

I read with interest the findings of Abe et a1 (1975) concerning the forms of vitamin B,, in the blood and bone marrow of patients with pernicious anaemia. Three out of five patients continued to have no or low concentrations of niethylcobalamin 24 h following the administration of IOO pg of cyanocobalaniin. The relatively high concentration of 5’-deoxyadenosylcobalamin before therapy and its continued rise following therapy would suggest that if there is a rapid turnover of methylcobalamin it is in the direction of the adenosyl form. Thcrefore, the low concentration of marrow inethylcobalaniin during the first 24 h of therapy would make it unlikely that the homocysteinemethionine niethylfolate transferase, the methylcobalamin-dependent reaction, is a critical step in niegaloblastic maturation due to vitamin B deficiency. This is particularly so when considering that the megaloblastic appearance of the bone marrow is corrected in 24 h or sooner following therapy (Davidson e t al, 1942; Stasney & Pizzlato, 1943) and that the ferrokinetic evidence of a repopulation of the bone marrow by nornioblastic red cell precursors is apparent on thc second day of therapy (Hillman et al, 1968). The data provided in this article seem to be in keeping with the suggestion that vitamin B,,, in a form other than the methyl, corrects the niegaloblastic development. This corrcction could be through the formation of the enzyme thymidylate synthetase (Haurani, 1973).

FARIDI. HAURANI 2 February 1976

C a r d e z a Foundation for Heniatologic Research, T h o m a s j e f e r s o n University, Philadelphia, PA 19107, U.S.A. REFERENCES

ABE,T., GIBBS,B. & COOPER, B.A. (1975) Fornis of vitamin B I Zin blood and bone marrow in patients with pernicious anaemia. British Journal of HaematOlOgY, 31, 493. DAVIDSON, L.S.P., DAVIS,L.J. & INNES,J. (1942) The effect of liver therapy on erythropoiesis as observed by serial sternal puncture in twelve cases of pernicious anaemia. Quarterly Joirrnal of Medicine, IT. 19. HAURANI, F.I. (1973) Vitainin B I 2 and the megaloblastic development. Science, 182, 7 8 .

HILLMAN, R.S., ADAMSON, J. & BURKA,E. (1968) Characteristics of vitamin B I 2 correction of the abnormal erythropoiesis of pernicious anemia. Blood, 31, 419. STASNEY, J. & PIZZLATO, P. (1943) Serial bone marrow studies in pernicious anemia. Proceedingr of the Society .for Experimental Biology and Medicine, 51, 3 3 5 . 3 3 8 , 340.

Letter: Vitamin b12 analogues.

British Journal of Haematology, 1976,33, 152. Correspondence VITAMIN B ANALOGUES I read with interest the findings of Abe et a1 (1975) concerning t...
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