Patterns of plasma cobalamins in control subjects and in cases of vitamin B₁₂deficiency

Abstract

SYNOPSIS A method for thin-layer chromatography and bioautography of plasma cobalamins is described. It requires only 5 ml of blood.Results are reported in 35 healthy people and hospital controls, and in 14 cases of untreated pernicious anaemia. In the control group there were two major components, methylcobalamin and a component which is probably a mixture of hydroxocobalamin and deoxyadenosyl cobalamin. Many cases of untreated pernicious anaemia showed a characteristic pattern in which methylcobalamin was reduced in relation to hydroxocobalamin. This pattern was also seen in one vegan who was taking a diet without B12 supplement. A minority of subjects showed traces of cyanocobalamin; this compound was not confined to smokers.The significance of the results and possible diagnostic utility of the technique are discussed.

Effect of Vegetarianism and Smoking on Vitamin B12, Thiocyanate, and Folate Levels in the Blood of Normal Subjects

“…In a vegan who did not receive any B,,. supplement Linnell et al (1969) found a serum %. value of 100 pg/ml, measured by the isotopic assay that we also used.…”

“…The concentration of true cyanocobalamin in the blood may be raised in tobacco amblyopia and hereditary optic neuropathies in the presence of a normal total B1, level; this rise is thought to be functionally unimportant (Wilson et al, 1971;Matthews 1971). The other important feature shown by bioautography is that methylcobalamin is biologically the most important fraction of vitamin B1, and that this is the fraction which is depleted in pernicious anaemia and not hydroxocobalamin, which may in some cases be the predominant component (Linnell et al, 1969). In view of this, the earlier suggestion of Smith (1961a, 1961b) that the difference between values A and B represents the amount of hydroxocobalamin in the blood and that this is the physiologically active fraction concerned with the detoxication of cyanide appears untenable.…”

Accurate assessment and identification of naturally occurring cellular cobalamins

“…The standard protocols for extraction and purification of Cbls from biological samples involve heated ethanol extraction, treatment with very alkaline or acidic solutions, and a final organic-phase extraction step (13)(14)(15)(16)(17). The major Cbls extracted and identified in these early studies included methylcobalamin (MeCbl), adenosylcobalamin (Ado-Cbl) and aqua(hydroxo)cobalamin (H 2 OCbl + /HOCbl) [reviewed by Gimsing and Nexo (18)].…”

Experimental approach in chemical pathology.

“…In the method we have developed the plasma extracts are run on thin-layer chromatograms with precautions againstlight, and the separated cobalamins, which are quite invisible, are identified by the growth-response of a B1,-dependent organism (Linnell et al, 1969c). The resulting spots, stained crimson with a redox indicator, can thus be located, and estimated by photometric scnng.…”