Three topics affecting cobalamin, folate, and homocysteine that have generated interest, activity, and advances in recent years are discussed. These are: (I). the application of an expanded variety of tools to the diagnosis of cobalamin deficiency, and how these affect and are affected by our current understanding of deficiency; (II). the nature of the interaction between homocysteine and vascu...

In adults, the diagnostic utility of total homocysteine (tHcy) determination is well established. Elevated tHcy is a risk factor for adverse pregnancy outcomes [1,2], impaired cognitive function [3] and occlusive arterial and venous disease [4], and the use of tHcy has been recommended in cardiovascular risk assessment [5]. Levels of tHcy are increased in folate and cobalamin deficiencies, and ...

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/mI). Several cobalaminbinding protein abnormalities coexisted and antedated cobal...

Cobalamin-dependent methionine synthase is a large enzyme composed of structurally and functionally distinct regions. Recent studies have begun to define the roles of several regions of the protein. In particular, the structure of a 27 kDa cobalamin-binding fragment of the enzyme from Escherichia coli has been determined by X-ray crystallography, and has revealed the motifs and interactions res...

Until the 1990s, the most common recognised cause of cobalamin deficiency in adults was pernicious anaemia [1]. Thanks to progress made during the last 10-20 years in the understanding of vitamin B12 metabolism, “new” physiopathological concepts have emerged or recognized, including a controversial medical concept entitled food-cobalamin malabsorption (FCM) in Anglo-Saxon literature, also known...

Samples of maternal and foetal blood and of human milk, cow's milk, and dried cow's milk have been analysed for cobalamins by chromatography and bioautography. Plasma cobalamins in late pregnancy and after delivery differed quantitatively from those in healthy non-pregnant women. Differences in the proportions of plasma cobalamins were also observed between mothers and their newborn infants. Th...

PURPOSE Determine acceptance of and compliance with intranasal cobalamin (vitamin B12) replacement therapy. METHODS Veteran subjects were recruited from VA Outpatient facilities in Hawai'i. Information was obtained by interview and medical record review. Subjects received the standard dose of intranasal cobalamin of 500 micrograms intranasally, once a week. A follow-up questionnaire was admin...

Cobalamins are stored in high concentrations in the human liver and thus are available to participate in the regulation of hepatotropic virus functions. We show that cyanocobalamin (vitamin B12) inhibited the HCV internal ribosome entry site (IRES)-dependent translation of a reporter gene in vitro in a dose-dependent manner without significantly affecting the cap-dependent mechanism. Vitamin B1...

Methylmalonic acid concentrations are increased in serum in vitamin B12 (cobalamin) deficiency. Here I demonstrate the successful use of anion-exchange extraction for improving newly developed analytical procedures and describe well-documented, reliable performance of this method for rapid determination of methylmalonic acid. The sorbent counter ion is formate, and the elution solvent is formic...

Methanotrophs play a key role in the global carbon cycle, in which they affect methane emissions and help to sustain diverse microbial communities through the conversion of methane to organic compounds. To investigate the microbial interactions that cause positive effects on methanotrophs, cocultures were constructed using Methylovulum miyakonense HT12 and each of nine nonmethanotrophic bacteri...