Liver B₁₂ in Subjects With and Without Vitamin B₁₂ Deficiency. A Quantitative and Qualitative Study

Abstract

In six subjects with normal serum‐B12 level the liver B12 was about 1 μg per gram liver tissue wet weight. In the livers of eleven subjects with B12 deficiency the B12 content was only one fourth to one fiftieth of the normal amount. Methyl‐B12, deoxyadenosyl‐B12 and hydroxo‐B12 were demonstrated in control livers by the chromatographic‐bioautographic technique. Deoxyadenosyl‐B12 was the major component. The liver methyl‐B12/deoxyadenosyl‐B12 quotient was increased in four of seven subjects with vitamin B12‐deficiency.

Systematic Review on Daily Vitamin B12 Losses and Bioavailability for Deriving Recommendations on Vitamin B12 Intake with the Factorial Approach

“…Our review on total body stores of vitamin B12 showed that in adults mean total body stores are between 1.1 and 3.9 mg. This is in line with reported mean values on vitamin B12 liver content (0.7-1.0 µg/g liver) [49,50,51,52,53] and liver weights [men: 1,677 g (range: 670-2,900), women: 1,475 g (range 508-3,081) [54]] assuming that half of vitamin B12 in the human body is stored in the liver [39]. Based on these stores and a rate of loss of 0.13% of the store per day, total losses would range from 1.4 to 5.1 µg per day under the assumption that the size of the total body store of vitamin B12 is the major determinant of the amount of vitamin B12 lost per day (table 5).…”

Molecular Imaging of Labile Iron(II) Pools in Living Cells with a Turn-On Fluorescent Probe

“…54 As an additional control experiment, we therefore tested the fluorescence response of IP1 towards cobalamin (vitamin B 12 ), which is the dominant form of cobalt in mammalian systems under physiological conditions. 55 As expected, because the cobalt ion in cobalamin is tightly bound, no change in emission of IP1 was observed after reaction with 20 μM cobalamin, a level which is 20-fold above the maximum limit found in the human body. 55 In addition to cobalamin, the fluorescence response of IP1 toward Fe 2+ in the presence of various concentrations of Co 2+ and Zn 2+ was also evaluated under conditions that mimic cellular overload of these metal (Fig.…”

Activity-based sensing fluorescent probes for iron in biological systems

“…Binding of Fe 2+ and O 2 at this recognition motif results in an oxidative cleavage of the C–O bond and release of a fluorescent fluorescein alcohol [45]. The Fe 2+ -triggered turn-on response for IP1 is highly selective over other biologically relevant metals, noting that mammalian Co 2+ exists primarily in tightly-bound vitamin B12/cobalamin forms [47].…”