Concentrations Of Cyanocobalamin Research Articles

Some metabolic effects of sodium nitroprusside in man.

The infusion of sodium nitroprusside during surgical operations produced plasma levels of cyanide of up to four times the control value. Plasma thiocyanate showed little change except during prolonged infusion of the drug, but total plasma B(12) tended to fall, as did methylcobalamin. Other cobalamins showed little change after nitroprusside infusion for short periods. During longer infusions the ratio of methylcobalamin to adenosyl + hydroxocobalamin fell and cyanocobalamin concentrations were high.

Activities of various cobalamins for Euglena gracilis with reference to vitamin B 12 assay with Euglena.

Coenzyme B(12) and methylcobalamin in water are less active in promoting growth of Euglena gracilis Z strain than the same concentrations of cyanocobalamin and hydroxocobalamin which are equally active. When bound to human serum or human liver homogenate, however, the activities of these four cobalamins do not differ significantly with one exception. The results suggest that the Euglena assay using cyanocobalamin standards is not satisfactory for quantitation of coenzyme B(12) and methylcobalamin in water but acceptable when coenzyme B(12) and methylcobalamin are bound to serum or liver. Sulphitocobalamin in water is as active as cyanocobalamin and hydroxocobalamin but nitritocobalamin is less active. Factor B, the monocarboxylic acids of cyanocobalamin and hydroxocobalamin, and the dicarboxylic acid of cyanocobalamin in water were inactive.

The distribution of Co58-labeled vitamin B12 in the rat with fatty metamorphosis and cirrhosis of the liver.

Abstract 1.1. The distribution pattern of Co 58 -cyanocobalamin, mainly in kidney and liver, has been studied in the normal rat and the rat with fatty metamorphosis and cirrhosis of the liver. 2.2. The fatty and cirrhotic liver has been found to have a diminished binding capacity for Co 58 -cyanocobalamin. The data suggest that this binding capacity is more severely impaired in the fatty than in the cirrhotic liver. 3.3. In the normal rat, the concentration of administered Co 58 -cyanocobalamin in the liver increases gradually and reaches a maximum around the fourteenth day; in the fatty liver the concentration is smaller on the fourteenth than on the second day. 4.4. The kidney of the animals with fatty metamorphosis and cirrhosis of the liver has been shown to have an increased binding capacity for Co 58 -cyanocobalamin. In the normal kidney, the Co 58 -cyanocobalamin concentration diminishes between the second and fourteenth days following the administration of the labeled vitamin. In contrast, the kidney of the animal with fatty metamorphosis of the liver maintains or increases its Co 58 -cyanocobalamin content during this period. 5.5. It is suggested that the diminished binding capacity of the damaged liver leads to the utilization of other potential binding sites for the vitamin, especially the kidney.

The influence of vitamin B12 on growth rate and cell composition of the flagellate Ochromonas malhamensis.

SUMMARY: In cultures of the flagellate Ochromonas malhamensis the rate of growth is determined by the concentration of cyanocobalamin up to a limit at which a maximum growth rate is achieved. In organisms grown exponentially with different rate-limiting concentrations of cyanocobalamin, the amounts of protein and nucleic acids were approximately proportional to the rates at which the organisms had grown. With increasing growth rate the concentrations of riboflavin, nicotinic acid, pantothenic acid and chlorophylls increased. Carbohydrate showed little change, whereas fat and ‘free’ amino-nitrogen diminished in concentration as the growth rate increased. In cultures of O. malhamensis grown with limiting or near-limiting concentrations of cyanocobalamin and with increasing concentrations of chloramphenicol, the rates of division declined asymptotically to a low value corresponding with 500 μg. chloramphenicol/ml. culture medium. Inhibition of growth caused by the antibiotic was annulled by increasing the concentration of cyanocobalamin in the culture medium.

The clinical significance of serum cyanocobalamin (vitamin B12) in liver disease.

Concentrations of cyanocobalamin (vitamin B 12 ) in serum have been found to be elevated in acute 1-4 and chronic 2,5,6 liver disease associated with hepatocellular damage. In acute viral hepatitis the rise in serum cyanocobalamin was most pronounced in the first two weeks of the disease, when bilirubinemia is marked and the liver-function tests indicative of hepatocellular damage are positive. In cirrhosis of the liver elevated cyanocobalamin values were found when clinical and laboratory signs of active hepatitis were present. In extrahepatic obstructive jaundice the serum cyanocobalamin level was found to be normal. 1,3 These studies were extended to a larger group of patients. The serum cyanocobalamin values were correlated with the common liver-function tests and particularly with the degree and duration of bilirubinemia. It appeared from these studies that the estimation of serum cyanocobalamin may serve as an early and sensitive test for differentiating the various types of jaundice.