This study describes the identification and the structural and spectroscopic analysis of a cobalamin-binding protein (termed CobDH) implicated in O-demethylation by the organohalide-respiring bacterium Desulfitobacterium hafniense DCB-2. The 1.5 Å resolution crystal structure of CobDH is presented in the cobalamin-bound state and reveals that the protein is composed of an N-terminal helix-bundl...

A patient presented at the age of 77 yr with a low serum cobalamin level. Subsequent study showed that he had persistently very low R binder (TC I) cobalamin-binding capacity in serum (< 5 ng/liter versus 213 ± 171 ng/liter in normal controls). and that almost all of his endogenous serum cobalamin was carried by TC II instead of TC I. His saliva also demonstrated virtually undetectable R binder...

Serum cobalamin and homocysteine levels were studied in patients with chronic myelogenous leukemia (CML) and in stem cell donors treated with granulocyte-colony stimulating factor (G-CSF). Cytoreductive treatment in patients with CML resulted in a decrease of cobalamin and homocysteine levels. In stem cell donors cobalamin and homocysteine levels increased after G-CSF administration. The increa...

BACKGROUND Low serum cobalamin levels are often found in apparently normal older subjects. A major worry of leaving cobalamin deficiency untreated is that it may lead to subtle deterioration in cognitive function. OBJECTIVES To investigate the effect of supplementation on the cognitive function of older people with cobalamin deficiency by a randomized trial. METHODS Fifty Chinese subjects m...

Methylmalonic acid (MMA) concentrations are increased in cobalamin (vitamin B12) deficiency, but the relative diagnostic usefulness of determination of MMA in serum vs urine has not yet been assessed. We obtained urine collections and matched serum samples from 28 healthy volunteers and from 20 consecutive patients admitted for clinical and hematological evaluation because of low cobalamin conc...

BACKGROUND Hyperthyroidism, the most common endocrine disorder in cats, has been associated with low serum cobalamin concentrations. Whether this is a functional cobalamin deficiency of clinical importance has not been assessed. HYPOTHESIS/OBJECTIVES Cats with hyperthyroidism experience a functional cobalamin deficiency which correlates with their clinical catabolic state and is reversible wi...

BACKGROUND Two proteins carry vitamin B12 in plasma. Transcobalamin (TC) carries approximately 25% of total plasma vitamin B12 and is 6% to 20% saturated with cobalamin. Haptocorrin (HC) binds approximately 80% of total cobalamin and is largely saturated with cobalamin. METHODS We investigated the distribution and the relationship between concentrations of cobalamin, total and holo forms of T...

BACKGROUND Exclusive breastfeeding for 6 months is assumed to ensure adequate micronutrients for term infants. Our objective was to investigate the effects of prolonged breastfeeding on B vitamin status and neurodevelopment in 80 infants with subnormal birth weights (2000-3000 g) and examine if cobalamin supplementation may benefit motor function in infants who developed biochemical signs of im...

A case of transcobalamin II deficiency with several unique features is described. The clinical presentation was typical, except for a slightly delayed age at presentation and the occurrence of apparent neurologic dysfunction from the beginning. The unusual biochemical feature was a low serum cobalamin level (97 pg/ml). Several cobalamin-binding protein abnormalities coexisted and antedated coba...

A patient presented at the age of 77 yr with a low serum cobalamin level. Subsequent study showed that he had persistently very low R binder (TC I) cobalamin-binding capacity in serum (< 5 ng/liter versus 213 ± 171 ng/liter in normal controls). and that almost all of his endogenous serum cobalamin was carried by TC II instead of TC I. His saliva also demonstrated virtually undetectable R binder...