Results with radioisotopic assay of serum B₁₂using serum binding agent

Abstract

Results obtained with a radioisotope method for assay of serum vitamin B12(Ekins and Sgherzi, 1965) are described. This method, which uses serum as binding agent, is simple, easy to set up, and suitable for routine diagnostic use. It gives results extremely similar to those obtained with standard microbiological assays.

Distribution of Endogenous Cobalamin between the Transcobalamins in Various Mammals

“…A column was freshly prepared for each experiment. The absorbance of each fraction was measured at 280 nm and its total cobalamin concentration determined by radioisotopic assay (Matthews, Gunasegaram & Linnell, 1967;England et al, 1976). The sensitivity of the assay was well below 4.6 pmol/l over the required range of total cobalamin concentrations (5-1 8 pmol/l) (England et al, 1976).…”

Abnormal cobalamin metabolism in a megaloblastic child with homocystinuria, cystathioninuria and methylmalonic aciduria

“…Total cobalamin (Cbl) in plasma and erythrocytes was estimated by a radioisotopic assay using human serum as binding agent (Matthews et al, 1967). MeCbl, AdoCbl and hydroxocobalamin (OHCbl) were estimated by thin-layer chromatography and bioautography (Linnett et al, 1974).…”

Cobalamins in Fibroblasts Cultured from Normal Control Subjects and Patients with Methylmalonic Aciduria

“…Precuations were taken to avoid exposure of samples to light. Total vitamin B,, was estimated on I-ml aliquots of cell suspension by a radioisotopic assay (19). Total nitrogen was estimated by an automated micro-Kjeldahl method (30) using a continuous digester and a modified digestion mixture of 95% sulfuric acid containing 30 g selenium dioxide and 10 ml perchloric acid/liter (9).…”