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Changes in circulating transcobalamin II after injection of cyanocobalamin.
N Engl J Med. 1977 Jun 23; 296(25):1427-30.NEJM

Abstract

Since transcobalamin II is the plasma binder of vitamin B12(cobalamin) that mediates delivery of cobalamin to tissues, we measured circulating levels of transcobalamin II after intravenous injection unlabeled cyanocobalamin in 12 control subjects and, because the liver is a major source of transcobalamin II, in eight patients with decompensated cirrhosis. Thirty minutes after injection of cyanocobalamin (200 ng per kilogram of body weight), total transcobalamin II (unsaturated plus cobalamin bound) declined in all 20 subjects to levels that averaged (+/- S.E.) 53.5 +/- 4.6 per cent of initial values. Subsequently, unsaturated transcobalamin II rapidly increased so that by eight hours, total transcobalamin II approached preinjection levels. Rates of regeneration of transcobalamin II were similar in control subjects and patients with liver disease. Unlike total transcobalamin II, total transcobalamin I was unaltered by injection of cyanocobalamin. Moreover, addition of cyanocobalamin to plasma in vitro did not alter measurements of total transcobalamin II. The rapid response of circulating transcobalamin II to cyanocobalamin injection strongly supports a dynamic role for this polypeptide during transport of a relatively large load of cobalamin.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

865512

Citation

Donaldson, R M., et al. "Changes in Circulating Transcobalamin II After Injection of Cyanocobalamin." The New England Journal of Medicine, vol. 296, no. 25, 1977, pp. 1427-30.
Donaldson RM, Brand M, Serfilippi D. Changes in circulating transcobalamin II after injection of cyanocobalamin. N Engl J Med. 1977;296(25):1427-30.
Donaldson, R. M., Brand, M., & Serfilippi, D. (1977). Changes in circulating transcobalamin II after injection of cyanocobalamin. The New England Journal of Medicine, 296(25), 1427-30.
Donaldson RM, Brand M, Serfilippi D. Changes in Circulating Transcobalamin II After Injection of Cyanocobalamin. N Engl J Med. 1977 Jun 23;296(25):1427-30. PubMed PMID: 865512.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Changes in circulating transcobalamin II after injection of cyanocobalamin. AU - Donaldson,R M,Jr AU - Brand,M, AU - Serfilippi,D, PY - 1977/6/23/pubmed PY - 2001/3/28/medline PY - 1977/6/23/entrez SP - 1427 EP - 30 JF - The New England journal of medicine JO - N Engl J Med VL - 296 IS - 25 N2 - Since transcobalamin II is the plasma binder of vitamin B12(cobalamin) that mediates delivery of cobalamin to tissues, we measured circulating levels of transcobalamin II after intravenous injection unlabeled cyanocobalamin in 12 control subjects and, because the liver is a major source of transcobalamin II, in eight patients with decompensated cirrhosis. Thirty minutes after injection of cyanocobalamin (200 ng per kilogram of body weight), total transcobalamin II (unsaturated plus cobalamin bound) declined in all 20 subjects to levels that averaged (+/- S.E.) 53.5 +/- 4.6 per cent of initial values. Subsequently, unsaturated transcobalamin II rapidly increased so that by eight hours, total transcobalamin II approached preinjection levels. Rates of regeneration of transcobalamin II were similar in control subjects and patients with liver disease. Unlike total transcobalamin II, total transcobalamin I was unaltered by injection of cyanocobalamin. Moreover, addition of cyanocobalamin to plasma in vitro did not alter measurements of total transcobalamin II. The rapid response of circulating transcobalamin II to cyanocobalamin injection strongly supports a dynamic role for this polypeptide during transport of a relatively large load of cobalamin. SN - 0028-4793 UR - https://www.unboundmedicine.com/medline/citation/865512/Changes_in_circulating_transcobalamin_II_after_injection_of_cyanocobalamin_ L2 - https://www.nejm.org/doi/10.1056/NEJM197706232962502?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -