Surface scintillation measurements in humans of the uptake of parenterally administered radioactive vitamin B12.

IN EARLIER WORK'. 2 the metabolism of vitamin B12 was studied in pa-tietits with pernicious and other nutritional anemias. The microbiological assay with E. coli mutant' and Euglena gracilis2 was used for the quantitation of vitamin B12 in urine and blood, following injection or oral administration of vita-mm B12 alone or with various gastric materials of humaii or animal origin, coi'-taming intrinsic factor. The output of vitamin B12 in the urine, as well as its levels iii the blood, were correlated in these studies with the hematologic status of patients studied and their hematopoietic responses to vitamin B12 therapy. In the present work we approached the problem of the metabolism of vitamin B12 by isotopic technic, using vitamiii B12 containing radioactive Co60. In animals the radioactive vitamin B12 was used for quantitation of the excre-tion of vitamin B12 in the urine and feces3-8, as well as for the study of its absorption and storage in various organs of the body. The radioactivity counts were obtained on rats postmortem, and conclusions were drawn regarding the metabolic turnover of vitamin B12 in the animal body. On living human subjects radioactive vitamin B12 was previously used only for determination of the excretion of vitamin B12 in the feces in cases of pernicious anemia,9 10 sprue, " or following total gastrectomy,'2 or in the urine.'3 New Jersey, who supplied us generously with radioactive vitamin B,2 on allocation of Isotope Division of the Atomic Energy Commission is gratefully acknowledged. Medical College, in obtaining the radioactive material from the Atomic Energy Commission, as well as in some technical matters connected with the equipment. and performance of measurements is thankfully acknowledged. was most helpful in assigning the case of total gastrectomy from the surgical wards for these studies. Fifth Avenue Hospitals, were very helpful in assigning patients for study, and their cooperation is gratefully acknowledged. sIiss Rose Schiseider, Ph.D., performed some of the radioactivity counts on (lie first two cases. All ptttietsts who submitted themselves to these prolonged studies are gratefully remembered. 95 For personal use only. on April 14, 2017. by guest www.bloodjournal.org From 96 INTRINSIC FACTOR AND VITAMIN B12 In this work we have measured the uptake of the radioactive vitamin B12 by various areas of the human body, as determined by surface measurements of the radioactivity on cutaneous proj ections of underlying organs following parenteral administration of Co60-B12. The technic is similar to that …