Cobalamin metabolism and function were investigated at the levels from transcobalamin II (TCII) receptor to the cobalamin-dependent enzymes, methionine synthase and methylmalonyl-CoA mutase, in a methionine-dependent (P60) and a methionine-independent (P60H) glioma cell line. Using P60H as reference, the P60 cells cultured in a methionine medium had slightly lower TCII receptor activity and nor...

BACKGROUND Arsenic is a carcinogen to which 35 million people in Bangladesh are chronically exposed. The enzymatic transfer of methyl groups to inorganic As (iAs) generates monomethylarsonic (MMA) and dimethylarsinic acids (DMA) and facilitates urinary As (uAs) elimination. This process is dependent on one-carbon metabolism, a pathway in which folate and cobalamin have essential roles in the re...

In this study, we showed that cyanocobalamin dodecylamine, a ribose 5'-carbamate derivative of cyanocobalamin, was absorbed and accumulated to significant levels by Caenorhabditis elegans and was not further metabolized. The levels of methylmalonic acid and homocysteine, which serve as indicators of cobalamin deficiency, were significantly increased in C. elegans treated with the dodecylamine d...

A 5-year-old Amish boy diagnosed at birth as having a defect in intracellular cobalamin metabolism, cobalamin C disease (cb1C), presented to the pediatric ophthalmology service with severe visual impairment. Ophthalmoscopy showed bilateral bull's eye macular lesions. Visual loss occurs from retinal degeneration in cb1C disease. This report highlights the importance of post-natal metabolic testi...

A marine eukaryotic microorganism, Schizochytrium limacinum SR21, had the ability to absorb and accumulate exogenous cobalamin, which was converted to the cobalamin coenzymes 5'-deoxyadenosylcobalamin (20.1%) and methylcobalamin (29.6%). A considerably high activity (about 38 mU/mg protein) of 5'-deoxyadenosylcobalamin-dependent methylmalonyl-CoA mutase (EC 5.4.99.2) involved in amino acid and ...

BACKGROUND Differences in the distribution of the MTRR rs326119 polymorphism (c.56 + 781 A > C) between patients with congenital heart disease (CHD) and controls have been described in Chinese individuals. The association is thought to be due to deregulation of homocysteine-cobalamin pathways. This has not been replicated in other populations. The primary objective of this study was to assess t...

BACKGROUND Vitamin B12 (cobalamin) is an essential cofactor in several metabolic pathways. Intracellular conversion of cobalamin to its two coenzymes, adenosylcobalamin in mitochondria and methylcobalamin in the cytoplasm, is necessary for the homeostasis of methylmalonic acid and homocysteine. Nine defects of intracellular cobalamin metabolism have been defined by means of somatic complementat...

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...

To investigate the fate of intrinsic factor and cobalamin during cobalamin absorption, we incubated enterocytes isolated from guinea pig ileum for periods of up to 30 min with (57)Co-labeled cyano-cobalamin bound either to human intrinsic factor or to rabbit intrinsic factor biosynthetically labeled with [(35)S]methionine. When the labeled complex was incubated for 30 min with isolated ileal ce...

OBJECTIVES The etiology of conotruncal heart defects (CHD) remains unknown; however relation between homocysteine, folate levels, and congenital heart disease was found. With this perspective in mind, the aim of the study was to investigate biomarkers of homosyteine metabolism pathway in mothers and their neonates with CHD. MATERIAL AND METHODS Forty-three pairs of mothers and their neonates ...