CONTEXT AND OBJECTIVE: The prevalence of vitamin B12 deficiency varies from 5.8% to 30% among patients undergoing long-term treatment with metformin. Because of the paucity of data on Brazilian patients, this study aimed to determine the frequency of B12 deficiency and related factors among Brazilian patients with type 2 diabetes mellitus (T2DM) using metformin. DESIGN AND SETTING: Cross-sect...

The role of vitamin B12 in the folate dependent biosynthesis of thymidine nucleotides is controversial. In an attempt to clarify this, three methods have been used to assess the relative efficacy of vitamin B12 (hydroxocobalamin) and various folate analogues in titrated concentrations at correcting 'de novo' thymidylate synthesis by megaloblastic human marrow cells: (1) The deoxyuridine (dU) su...

Vitamin B12 plays an essential role in fetal and infant development. In regions where animal source food consumption is low and perinatal supplementation is uncommon, infants are at risk of vitamin B12 deficiency. In this secondary analysis, we measured total vitamin B12 concentrations in maternal and infant serum/plasma and breast milk among two samples of mother-infant dyads in Canada (assess...

OBJECTIVE The objective of this study was to evaluate the presence of vitamin B12 deficiency and the factors associated with serum vitamin B12 levels in a sample of metformin-treated Brazilian diabetic patients. METHOD Cross-sectional study. RESULTS 144 patients were included. Serum vitamin B12 levels were low (< 125 pmol/L) in 10 patients (6.9%) and possibly low (125 - 250 pmol/L) in 53 pa...

Incorporation of vitamin B12 into L1210 cells requires the protein binder transcobalamin II (TCII). The process is saturable, follows Michaelis-Menten kinetics (Km = 2.5 X 10(-9) M at 37 degrees C), is both temperature and calcium (K50 - 1 X 10(-6) M) dependent, and is inhibited by apo-TCII, indicating the presence of a TCII specific receptor on the cell membrane. B12 also leaves the cell by a ...

1. DNA synthesis in the bone marrow and lymphocytes of the vitamin B12-deficient fruit bat (Rosettus Aegyptiacus) has been studied via the deoxyuridine (dU) suppression test. 2. In contrast to vitamin B12 deficiency in man, the dU suppression test was not abnormal in the vitamin B12-deficient bat, and this correlates with the reported finding that the latter does not develop megaloblastic anaem...

A review of how vitamin B12 is used by the human body and the role it plays in DNA mutation is presented. Vitamin B12 is a compound needed for healthy function of the human body but produced downstream of the point of absorption in the digestive system, rendering it unusable. One may become B12 deficient in a variety of ways including lack of intake, disruption of B12 absorption due to disease,...

The wake-sleep rhythm is a typical circadian rhythm. It has been reported that severely disturbed wake-sleep rhythms are improved by the administration of vitamin B12. This study was designed to clarify whether vitamin B12 is universally related to the circadian rhythm. Three-week-old male Wistar Kyoto rats were fed a vitamin B12 deficient diet for 3 months. Then some of them were given intrape...

A radioisotope dilution assay for vitamin B12, using hemoglobin-coated charcoal, was modified in several respects, the most prominent of which was the use of cyanide extraction of sera. With these modifications, the B12 levels were significantly higher in sera from normal subjects and patients with folate deficiency, whereas sera from patients with pernicious anemia and other B12-deficient stat...

BACKGROUND Vitamin B12 deficiency is prevalent in many countries of origin of refugees. Using a threshold of 5% above which a prevalence of low Vitamin B12 is indicative of a population health problem, we hypothesised that Vitamin B12 deficiency exceeds this threshold among newly-arrived refugees resettling in Australia, and is higher among women due to their increased risk of food insecurity. ...