Pancreatic proteases degrade the protein moiety of the R protein-cobalamin complex but not the intrinsic factor-cobalamin complex. Accordingly, we used these two proteins as substrates in an in vitro enzymatic assay to assess pancreatic function by incubating basal jejunal fluids with a mixture of intrinsic factor and cyano[57Co]cobalamin coupled to R-type protein and then using immunoprecipita...

Diagnosing cobalamin deficiency is often difficult. We investigated the diagnostic strategies that 224 general practitioners used to assess cobalamin status and the criteria on which they based their decisions to supplement patients. From all serum cobalamin analyses carried out at a single laboratory during 1993, individuals with serum cobalamin concentrations <300 pmol/L were identified, and ...

OBJECTIVE To study free- and protein-bound cobalamin absorption and the correlation with atrophic gastritis in healthy middle-aged and older subjects. DESIGN A cross-sectional study. PARTICIPANTS Fifty-two healthy subjects, aged 26 to 87 years, apparently free from conditions known to influence the cobalamin status. Middle-aged subjects were defined as those younger than 65 years of age (me...

BACKGROUND Measurement of serum cobalamin levels is routinely used to diagnose cobalamin deficiency. Surprisingly, approximately 15% of patients have high cobalamin levels and no consensus exists regarding the clinical implications. METHODS Hospital-treated patients above 18 years of age referred for serum cobalamin measurement were included in groups of patients [percentage cobalamin supplem...

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. Cobalamin-deficient bats had low hepatic methylmalonyl-CoA mutase holoenzyme activity, with elevated plasma and urinary methylmalonic acid levels. No significant changes could be demonstrated in the concentration...

Absorption of cobalamin free or bound to chicken serum was assessed in nine patients with pancreatic insufficiency. Simultaneously the in vitro effect of duodenal juice collected from six patients and seven controls was tested on labelled cobalamin complexed to chicken serum or to R salivary binder. Malabsorption of free cobalamin was observed in one of nine patients and in four of nine patient...

BACKGROUND There are conflicting results on the role of cobalamin and folate for epidemiology and carcinogenesis in colorectal cancer patients and the need of supplementation for prevention of chemotherapy toxicity. PATIENTS AND METHODS Serum cobalamin, folate, and homocysteine were analysed before and during the treatment of 93 patients with advanced colorectal cancer (ACRC) with first-line ...

BACKGROUND In patients with multiple myeloma a variety of metabolic events may occur. One of these are changes in the serum cobalamin (vitamin B12) concentration. Elevated as well as decreased serum cobalamin levels have been reported. The prevalence and clinical consequences of low cobalamin levels are largely unknown. OBJECTIVE To investigate the prevalence of low serum cobalamin levels in ...

Two pathways for methionine methyl formation, one cobalamindependent and one cobalamin-independent, corresponding to those observed in Escherichia coli PA 15 have been found in Aerobacter aerogenes. An initial difficulty in showing the cobalamin-dependent pathway in cellfree extracts proved to be due to the presence of enzymes which caused the removal of adenosylmethionine, a cofactor required ...

We have examined the distribution of cobalamin (coenzyme B12) synthetic ability and cobalamin-dependent metabolism among enteric bacteria. Most species of enteric bacteria tested synthesize cobalamin under both aerobic and anaerobic conditions and ferment glycerol in a cobalamin-dependent fashion. The group of species including Escherichia coli and Salmonella typhimurium cannot ferment glycerol...