Diatoms are responsible for ~40% of marine primary production and are key players in global carbon cycling. There is mounting evidence that diatom growth is influenced by cobalamin (vitamin B(12)) availability. This cobalt-containing micronutrient is only produced by some bacteria and archaea but is required by many diatoms and other eukaryotic phytoplankton. Despite its potential importance, l...

BACKGROUND Measurement of milk cobalamin is hampered by the high content of the cobalamin-binding protein haptocorrin, and limited data are available relating trustworthy measures of milk cobalamin to cobalamin status in healthy mothers and their children. OBJECTIVES The objectives were to explore the concentration of cobalamin and haptocorrin in foremilk and hindmilk during the first 9 mo of...

Cobalamin neuropathy was produced in cape fruit bats (Rousettus aegyptiacus) by a cobalamin-free diet combined with intermittent exposure to nitrous oxide, which inactivates cobalamin. There were no significant differences in S-adenosylmethionine/S-adenosylhomocysteine ratios in the central nervous system of cobalamin-deficient and cobalamin-replete bats. Taken with other data there are no grou...

The serum of an 84 year old man with disseminated carcinoma was found to contain extremely high concentrations of cobalamin and of a cobalamin binding protein with trans-cobalamin I characteristics. Tumour tissue samples obtained at necropsy contained considerably higher concentrations of cobalamin binding protein (R-binder) than normal tissues. Tumour tissues also contained increased concentra...

objective(s): incidence of neurocognitive and psychological disorders may be related to serum homocystein (hcy), cobalamin (vitamin b12 ) and folate levels in old people. the aim of this study was to assess the relation between hcy, cobalamin, folate and neurocognitive and/or psychological disorders in the elderly.   materials and methods: in this cross-sectional study, 280 subjects with ≥ 65 y...

In humans, three soluble extracellular cobalamin-binding proteins; transcobalamin (TC), intrinsic factor (IF), and haptocorrin (HC), are involved in the uptake and transport of cobalamin. In this study, we investigate a cobalamin-binding protein from zebrafish (Danio rerio) and summarize current knowledge concerning the phylogenetic evolution of kindred proteins. We identified a cobalamin bindi...

Vitamin B12 or cobalamin deficiency occurs frequently (> 20%) among elderly people, but it is often unrecognized because the clinical manifestations are subtle; they are also potentially serious, particularly from a neuropsychiatric and hematological perspective. Causes of the deficiency include, most frequently, food-cobalamin malabsorption syndrome (> 60% of all cases), pernicious anemia (15%...

We have read with interest Maktouf et al.’s letter about the etiological role of deficiencies of cobalamin or folate in megaloblastic anemia. In this large prospective series, they investigated 478 patients with megaloblastic changes in bone marrow smears and reported the demographic, biological and clinical findings in cobalamin-deficient patients and patients with pernicious anemia. Out of 43...

BACKGROUND Early detection of cobalamin deficiency is clinically important, and there is evidence that such deficiency occurs more frequently than previously anticipated. However, serum cobalamin and other commonly used tests have limited ability to diagnose a deficiency state. METHODS We investigated the ability of hematological variables, serum cobalamin, plasma total homocysteine (tHcy), s...

To determine whether the increased prevalence of low serum cobalamin concentrations in elderly people represents true deficiency, serum concentrations of cobalamin and folate and of metabolites that are sensitive indicators of cobalamin deficiency were measured in 548 surviving members of the original Framingham Study cohort. Serum cobalamin concentrations < 258 pmol/L were found in 222 subject...