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At least 19 recordsLinked to original sources
PubMed1977

Vitamin B12 and vitamin B12 binding proteins in liver diseases.

Serum vitamin B12 and vitamin B12 binding proteins (transcobalamins, TCS) were determined in patients with malaria, amoebic liver abscess, carcinoma of the liver, infectious hepatitis, cirrhosis and chronic myelocytic leukemia (CML) as well as in 60 blood donor subjects. Serum vitamin B12 in patients with infectious hepatitis, cirrhosis and CML were higher than that of the normal subjects. The values of unsaturated vitamin B12 binding capacity (UBBC) in patients with carcinoma of the liver, infectious hepatitis, cirrhosis were lower while that of patients with CML were higher than that of the normal subjects. A markedly increased TCI and decreased TCII was observed in patients with CML while these changes was much less in patients with other liver diseases. The difference was possibly due to a flooding of vitamin B12 from damaged liver cells into the circulation and the decreased synthesis of transcobalamins in patients with liver diseases while the increased granulocytes, the source of TCI, was much increased in patients with CML.

Carrier Proteins↗
PubMed1978

Vitamin B12 and vitamin B12 binding proteins in iron deficiency anaemia.

Vitamin B12 and vitamin B12 binding proteins were determined in 20 patients with iron deficiency anaemia who showed low haemoglobin, haematocrit, serum iron levels and hypochromic microcytic red blood cells. The serum vitamin B12 levels in these patients were significantly lower than that of the normal subjects. Nine of 20 patients had serum vitamin B12 less than 350 pg/ml. There was a significant increase in serum UBBC and TBBC levels in patient group and 9 of 20 patients had higher UBBC values than those of the normal subjects. The absolute values of TCI and TCII increased significantly while TCIII was within the normal limit even though the percentage of UBBC were not different from that of the normal subjects.

Anemia, Hypochromic↗
PubMed1977

HLA phenotype A2;B12 in vitamin B12 neuromyelopathy.

Severe neurological complications (either peripheral neuropathy, subacute combined degeneration of the cord or cerebral changes) are a characteristic feature in some patients with marked vitamin B12 deficiency. Although Addisonian pernicious anaemia (PA) is the major cause of this neurological syndrome, the disorder has been described in association with other conditions in which there is a profound depletion of vitamin B12 stores. Sixteen patients with vitamin B12 neuromyelopathy, associated with PA, have been HLA-typed for 27 alleles of the A and B loci and compared with 53 cases of PA without neurological damage and 60 controls of the same ethnic group. There is a significantly increased frequency of the HLA phenotype. A12;B12 (44% instead of 4% in PA patients without neurological damage) in the disease group studied (P less than 0.0005). The signficance of these findings in relation to the pathogenesis of vitamin B12 neuromyelopathy is discussed.

Anemia, Pernicious↗
PubMed1977

Serum vitamin B12 and folate levels, vitamin B12 and folic acid binding proteins in patients with primary carcinoma of the liver.

Serum vitamin B12, folic acid, vitamin B12 and folic acid binding protein concentration were determined in 31 patients with primary carcinoma of the liver. Serum vitamin B12 level was found to be higher in 16 of 31 (52%) patients with carcinoma of the liver and the mean value was also significantly higher than that of the control group. There was no significant difference between the mean values of serum UBBC of these 2 groups. TCI and TCIII increased while TCII decreased considerably in the patient group. Serum folate level in patients with primary carcinoma of the liver was significantly lower than that of the control group. About 39% of these patients had serum folate level lower than the lowest value of the control group. Serum FABP in the former group was also significantly higher than that of the latter group.

Adult↗
PubMed1977

Sparing effect of folic acid deficiency on the development of vitamin B12 deficiency in baboons fed a vitamin B12 deficient diet.

The effect of a vitamin B12 and folic acid deficient diet on juvenile and adolescent baboons (Papio cynocephalus anubis) was studied. The baboons developed clinical and hematological signs characteristics of folacin deficiency, although they were less severe in juvenile baboons. The signs disappeared when folic acid was replaced in the diet. The serum vitamin B12 levels increased in all baboons fed the vitamin B12 and folic acid deficient diet. When folic acid was added to the diet, the levels gradually decreased in adolescent baboons, liver vitamin B12 levels decreased to a lesser extent when fed a vitamin B12 and folic acid deficient diet than when fed a vitamin B12 deficient diet. In juvenile baboons fed a vitamin B12 and folic acid deficient diet, for 7 months and a vitamin B12 deficient diet for a further 11 months, liver vitamin B12 levels did not decrease at any time but were similar to those in baboons fed a vitamin B12 and folic acid supplemented diet.

Aging↗
PubMed1978

Reductive dechlorination and degradation of mirex and kepone with Vitamin B12.

Vitamin B12s effects the reductive dechlorination of mirex (dechlorane) in protic solvent systems, under both catalytic and stoichiometric conditions, mainly to yield compounds of composition C10Cl12-nHn, with n = 1-8, in which the basic dihomocubane cage structure is retained; the formation of cage-opened, reductively dehalogenated derivatives of 4,7-methanoindene occurs only to a very minor extent. The corresponding reactions of kepone (chlordecone), in contrast, occur with predominant formation of indene derivatives. Under certain mild conditions, vitamin B12s induces a fragmentation of kepone leading to the destruction of the dihomocubane moiety and the formation of an isolable organocobalamin having a C3Cl3H2 residue attached to the cobalt atom. In strongly alkaline media, the reaction of kepone with vitamin B12s may in addition yield high-molecular-weight condensation products of unknown constitution. Reactions of this type are of interest as prototypes of soil-decontamination processes.

Chemical Phenomena↗
PubMed1977

Serum vitamin B12, serum and red cell folates, vitamin B12 and folic acid binding proteins in women taking oral contraceptives.

Serum and red cell folate, FABP, serum vitamin B12 and vitamin B12 binding proteins were determined in 20 women taking oral contraceptives continuously for at least one year. Studies were also performed on 50 apparently healthy women with history of never taken or not taking oral contraceptives for at least one year as a control group. Serum vitamin B12 level, UBBC and TBBC in women taking oral contraceptives were slightly but not significantly lower than those of the control group. TCI and TCIII increased with a decreased TCII, so that UBBC was within the normal limit. Serum folate was non-significantly lower while red cell folate was significantly lower in the oral contraceptive group than those of the control group. However, all cases of the former showed red cell folate over 200 ng/ml. A highly significant increased serum FABP was demonstrated in the women taking oral contraceptives. This was probably due to the increased synthesis of the FABP in order to bind more folate from the low serum folate and the hormonally induced stimulation.

Adult↗
PubMed1978

Nutritional vitamin-B12 deficiency. Possible contributory role of subtle vitamin-B12 malabsorption.

Dietary deficiency of vitamin B-12 has been reported, yet most people ingesting vitamin-B12-deficient diets even for many years appear to achieve a balance that does not lead to overt signs and symptoms of deficiency. I present the case of a vegan of 25 years' duration who developed severe neurologic abnormalities due to vitamin-B12 deficiency. His diet provided 1.2 microgram of vitamin B12 daily at most. Despite normal Schilling test findings, he absorbed subnormal amounts of vitamin B12 given with ovalbumin. This poor absorption appeared to be related to his gastritis, achlorhydria, and subnormal intrinsic-factor secretion. Probably, vitamin-B12 deficiency in this patient resulted from both dietary restriction and the subtle malabsorption, neither of which would have sufficed alone to produce the clinical problem. Possibly such malabsorption may also be present in many of those vegans developing overt vitamin-B12 deficiency in whom Schilling test findings have been normal.

Diet, Vegetarian↗
PubMed1976

Inhibitory effect of eggs on vitamin B12 absorption: description of a simple ovalbumin 57Co-vitamin B12 absorption test.

Ovalbumin and egg yolks, mixed separately in vitro with radiocyanocobalamin (57 Co-vitamin B12), were served to normal volunteers in a cooked form. Ovalbumin, and to a lesser degree, egg yolks were observed to inhibit vitamin B12 absorption. This observation explains the rather poor assimilation of vitamin B12 from eggs labelled in vivo with 57 Co-vitamin B12.

Absorption↗
PubMed1976

[Vitamin B12 metabolism of human granulocytes. Differences in vitamin B12 uptake of normal granulocytes and CML leukocytes].

The total cell B12 level in chronic myelocytic leukaemia (CML) is low. The uptake of 57Co-cyanocobalamin by normal granulocytes, lymphocytes and CML leukocytes was studied. It was found that the uptake of vitamin B12 was dependent on its concentration. The velocity of the uptake by CML leukocytes was decreased. The reaction showed a non-competitive inhibition. Lymphocytes had the lowest uptake. Na2EDTA inhibited the vitamin B12 uptake of normal granulocytes.

Cobalt Radioisotopes↗
PubMedDate not supplied

Vitamin B12 absorption studies using radioactive vitamin B12: comparison of whole body retention and urinary excretion after flushing dose (Schilling's test).

Vitamin B-12 absorption of 12 healthy young male subjects was determined by using labelled vitamin B-12 by Schilling's test and whole body retention test. The whole body retention test was performed first using low energy Co57 isotope and a week later, Schilling's test was performed. Whole body retention showed a mean absorption of 56.5% while Schilling's test showed mean absorption of 16.9% in the same subjects. Data supports the whole body retention test being more accurate.

Adult↗
PubMed1979

The effect of oral contraceptives on vitamin B12 metabolism.

Serum vitamin vitamin B12 levels were determined in 199 women who were on a regimen of oral contraceptives of either the combination or sequential type and in a control group of 196 women. The group using oral contraceptive agents (OCA) had significantly lower serum levels of vitamin B12 vitamin as compared to those of the control group. A total of 19 women using OCAs had serum vitamin B12 levels that were lower than normal values. However, the Schilling test and urinary methylmalonate excretion in this group were normal. The OCA group had a significantly lower total serum vitamin B12 binding capacity, a lower total transcobalamin I level, and a higher transcobalamin III level. Our study suggests that the fall of serum vitamin B12 in OCA users is due to the changes in vitamin B12 binders of serum and does not represent vitamin B12 deficiency. Therefore, according to our data, there is no justification for vitamin B12 supplementation in users of oral contraceptives.

Absorption↗