Serum Co60 Vitamin B12 Binding Capacity in Some Hematologic Disorders.

Co58B12 ABSORPTION, PLASMA TRANSPORT AND EXCRETION IN PATIENTS WITH MYELOPROLIFERATIVE DISORDERS, SOLID TUMORS AND NON-NEOPLASTIC DISEASES*

“…The absorption in seven subjects with CML in the present study did not differ from this range, nor was the amount absorbed abnormal in the two subjects with myeloid metaplasia and a high serum B12. Heinrich and Erdmann-Oehlecker (12) The data also indicate that the plasma concentration of "unsaturated B12-binding protein" does not greatly influence the amount of B12 absorbed, since plasma from patients with CML has a markedly increased unsaturated B12-binding capacity (13)(14)(15)(16).…”

“…Therefore, the delayed plasma disappearance of the labeled vitamin may merely represent an isotope dilution effect. Since CML plasma has a high unsaturated B19-binding capacity (13)(14)(15)(16), an additional factor may be that as the tracer dose enters the plasma compartment a greater than normal fraction of it is tightly bound to plasma protein.…”

Some Characteristics of Binding of Vitamin B₁₂ by Normal Human Serum

“…Previous work reported from this laboratory has shown human serum to bind vitamin B12 in vitro in two phases (1). The first is constant for normals and elevated in myelocytic leukemia and some cases of myeloid metaplasia and polycythemia vera.…”

The Plasma Vitamin B12 Binding Substance: I. Its Detection in the Seromucoid Fraction of Plasma From Normal Subjects and Patients With Chronic Myelo-Cytic Leukemia *

“…control plasma bound 16 per cent of added Co58B12, whereas plasma from CML patients with a high serum B12 bound a mean of 47 per cent. Studies by others (3,4) More specific identification of the B12 binding naterial was attempted by using the scheme of Weimer, Mehl and Winzler (15) for the isolation of MP-1. These studies indicate that in sera from subjects with normal B12 concentrations the MP-1 fraction is not the major B12 binding substance.…”

“…The latter has been demonstrated in vitro (1)(2)(3)(4) using microbiologic assay or dialysis. In vivo studies in patients with CML have demonstrated a delay in the plasma disappearance of either an intravenously (5,6) or orally (7) administered dose of Co58B12 and would appear to confirm the in vitro findings.…”