Effect of storage on the apparent concentration of folate in erythrocytes, as measured by competitive protein binding radioassay.

Inadequate sample-preparation technique as a source of error in determination of erythrocyte folate by competitive binding radioassay.

Detergent activation of the binding protein in the folate radioassay.

A minor cow's whey protein associated with beta-lactoglobulin is used as binding protein in the competitive radioassay for serum and erythrocyte folate. Seeking to optimize the assay, we tested the performance of binder solutions of increasing purity. The folate binding protein was isolated from cow's whey by means of CM-Sepharose CL-6B cation-exchange chromatography, and further purified on a ...

The determination of erythrocyte folate concentration using a two-phase ligand-binding radioassay.

The concentration of folate in erythrocytes was determined using a two-phase ligandbIndIng radloasuy procedure described previously for measuring serum folate. The mean (± SD) folate concentration In erythrocytes of 20 normal subjects was 210 * 67 ng/mI. In 12 patients clinically folate deficient who had normal serum B2 concentration, the mean (± SD) erythrocyte folate was 71 * 39 ng/ml. Incuba...

A comparison of the interference of fatty acids in the competitive binding radioassay and radioimmunoassay for serum T4.

Several investigations have reported an increase, in stored serum, in apparent thyroxine (T4) concentration measured by competitive binding radioassay (CPBR) with thyroxine-binding globulin (TBG) as the binding reagent [l-7]. Watson and Lees [4] attributed this increase to the production of a “mimic T4” during storage. Recently, we [6] and Rootwelt [7], working independently, discovered that th...

Clinical and laboratory observations on serum folate-binding protein.

We studied the effect of serum folate-binding protein (FBP) on folate radioassays and the relationship of the serum level of unsaturated FBP to the serum folate level in various clinical states. Our modification of a heat-extracted radioassay was compared to a whole serum radioassay. Our results confirmed the existence of elevated serum levels of unsaturated FBP in some normal subjects, in some...