The photosynthetic coccolithophoid alga, Pleurochrysis (Hymenomonas) carterae, could take up and accumulate exogenous vitamin B12, most of which was converted into the coenzyme forms of vitamin B12. Two vitamin B12-dependent enzyme activities (methylmalonyl-CoA mutase, 2.6+/-0.4 nmol/min/mg protein and methionine synthase, 85.1+/-38.9 pmol/min/mg protein) could be found in a cell homogenate of ...

BACKGROUND The standard screening test for vitamin B12 deficiency, measurement of total plasma vitamin B12, has limitations of sensitivity and specificity. Plasma vitamin B12 bound to transcobalamin (holoTC) is the fraction of total vitamin B12 available for tissue uptake and therefore has been proposed as a potentially useful alternative indicator of vitamin B12 status. METHODS We compared t...

Extensive research on the formation of methionine has implicated vitamin B12 as a cofactor in the final reaction of the biosynthetic sequence. Since plants and fungi do not produce or require B12, an alternate reaction must also exist. It is thus not surprising that Escherichia coli has been found to possess two mechanisms for the methylation of homocysteine to methionine (9). These reactions a...

Background and objectives: Breast carcinoma is one of the most common malignant diseases among women worldwide. In Iraq there are noticeable elevation in incidence rates and prevalence of advanced stages of breast cancer. Cobalamin (vitamin B12) is essential micronutrient involved in one carbon metabolism and DNA methylation, which affects cancer. All of these may be change in breast cancer. Th...

Vitamin b12 deficiency (VBD) rarely cause involvement of optic nerve. Moreover, atrophy has been reported more commonly than neuritis secondary to VBD. Here, we report a 31-years old male presenting with bilateral but asymmetrical as the first clinical presentation undiagnosed VBD and showed drastic improvement in vision after replacement parenteral followed by oral Vitamin-B12. Thus, patients ...

Vitamin B12 is a cofactor of methionine synthase in the synthesis of methionine, the precursor of the universal methyl donor S-Adenosylmethionine (SAMe), which is involved in different epigenomic regulatory mechanisms and especially in brain development. A Vitamin B12 deficiency expresses itself by a wide variety of neurological manifestations such as paraesthesias, skin numbness, coordination ...

In 1953, the authors (1) reported that a decrease of thiamine and vitamin B12 was found in the blood as the result of the energy metabolism of cattle, and that the deficiency of the vitamins was com pletely protected against by a prophylactic injection of the vitamins at the beginning of the experiment. The intimate relation between both vitamins and metabolism was thus recognized for the forma...

Objective: Oral isotretinoin is the most effective agent in treatment of acne vulgaris. The risk pigmentation due to systemic may be associated with decrease serum levels Vit B12. study aims contribute literature by defining association between increase caused oral [O-ISO] use and low vitamin B12 level [vit-B12]. Methods: In our we evaluated 144 patients, who have facial acnes at medium degree ...

Using comparative analysis of genes, operons, and regulatory elements, we describe the cobalamin (vitamin B12) biosynthetic pathway in available prokaryotic genomes. Here we found a highly conserved RNA secondary structure, the regulatory B12 element, which is widely distributed in the upstream regions of cobalamin biosynthetic/transport genes in eubacteria. In addition, the binding signal (CBL...

Human deficiencies of folate and vitamin B12 result in adverse effects which may be of public health significance, but the magnitude of these deficiencies is unknown. Therefore, we examine the prevalence data currently available, assess global coverage of surveys, determine the frequency with which vitamin status assessment methods are used, and identify patterns of status related to geographic...