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Cobalamin malabsorption due to nondegradation of R proteins in the human intestine. Inhibited cobalamin absorption in exocrine pancreatic dysfunction.
J Clin Invest. 1980 Sep; 66(3):430-40.JCI

Abstract

In vivo studies demonstrate that the pancreatic enzymes and the ionic environment in the upper gastrointestinal tract are essential determining factors for transport and absorption of cobalamin in man. Jejunal fluid was aspirated from healthy human volunteers after administration of cyano[57Co]cobalamin preparations. Immunochemical analysis of the aspirates demonstrated that all isotopic vitamin was transferred to a protein that is identical to the gastric intrinsic factor in terms of molecular mass (57,500), ionic nature (mean pI, 5.09), and reactivity with anti-intrinsic factor sera. However, in the aspirates from patients with exocrine pancreatic dysfunction the vitamin was found to be coupled > 60% to a protein identical to R proteins in terms of molecular mass (125,000), ionic nature (mean pI, 3.51), and reactivity with anti-R protein and anti-intrinsic factor sera. The preferential transfer of cobalamin to R proteins in the patients and to intrinsic factor in healthy subjects was associated, respectively, with low and normal levels of pancreatic enzymes in the intestine and these in turn were paralleled respectively by impaired and normal ileal absorption of cobalamin. These findings confirm the suggestion that the formation of unabsorbable cobalamin complexes may be the reason of impaired vitamin absorption in exocrine pancreatic insufficiency. Observations made with other selected patients demonstrate: (a) that decreased enzyme activity and nondegradation of R proteins may also be due to nonactivation of pancreatic zymogens in an acidic pH of the intestinal juice the vitamin transported to the jejunum couples to intrinsic factor when pancreatic function is normal, and to intrinsic factor and R protein in exocrine pancreatic insufficiency. The observations made with these selected patients may explain why not all patients with exocrine pancreatic insufficiency develop imparied cobalamin absorption, and also why the malabsorption is corrected by the administration of bicarbonate in certain patients.

Authors

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Pub Type(s)

Journal Article

Language

eng

PubMed ID

7400324

Citation

Marcoullis, G, et al. "Cobalamin Malabsorption Due to Nondegradation of R Proteins in the Human Intestine. Inhibited Cobalamin Absorption in Exocrine Pancreatic Dysfunction." The Journal of Clinical Investigation, vol. 66, no. 3, 1980, pp. 430-40.
Marcoullis G, Parmentier Y, Nicolas JP, et al. Cobalamin malabsorption due to nondegradation of R proteins in the human intestine. Inhibited cobalamin absorption in exocrine pancreatic dysfunction. J Clin Invest. 1980;66(3):430-40.
Marcoullis, G., Parmentier, Y., Nicolas, J. P., Jimenez, M., & Gerard, P. (1980). Cobalamin malabsorption due to nondegradation of R proteins in the human intestine. Inhibited cobalamin absorption in exocrine pancreatic dysfunction. The Journal of Clinical Investigation, 66(3), 430-40.
Marcoullis G, et al. Cobalamin Malabsorption Due to Nondegradation of R Proteins in the Human Intestine. Inhibited Cobalamin Absorption in Exocrine Pancreatic Dysfunction. J Clin Invest. 1980;66(3):430-40. PubMed PMID: 7400324.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cobalamin malabsorption due to nondegradation of R proteins in the human intestine. Inhibited cobalamin absorption in exocrine pancreatic dysfunction. AU - Marcoullis,G, AU - Parmentier,Y, AU - Nicolas,J P, AU - Jimenez,M, AU - Gerard,P, PY - 1980/9/1/pubmed PY - 1980/9/1/medline PY - 1980/9/1/entrez SP - 430 EP - 40 JF - The Journal of clinical investigation JO - J Clin Invest VL - 66 IS - 3 N2 - In vivo studies demonstrate that the pancreatic enzymes and the ionic environment in the upper gastrointestinal tract are essential determining factors for transport and absorption of cobalamin in man. Jejunal fluid was aspirated from healthy human volunteers after administration of cyano[57Co]cobalamin preparations. Immunochemical analysis of the aspirates demonstrated that all isotopic vitamin was transferred to a protein that is identical to the gastric intrinsic factor in terms of molecular mass (57,500), ionic nature (mean pI, 5.09), and reactivity with anti-intrinsic factor sera. However, in the aspirates from patients with exocrine pancreatic dysfunction the vitamin was found to be coupled > 60% to a protein identical to R proteins in terms of molecular mass (125,000), ionic nature (mean pI, 3.51), and reactivity with anti-R protein and anti-intrinsic factor sera. The preferential transfer of cobalamin to R proteins in the patients and to intrinsic factor in healthy subjects was associated, respectively, with low and normal levels of pancreatic enzymes in the intestine and these in turn were paralleled respectively by impaired and normal ileal absorption of cobalamin. These findings confirm the suggestion that the formation of unabsorbable cobalamin complexes may be the reason of impaired vitamin absorption in exocrine pancreatic insufficiency. Observations made with other selected patients demonstrate: (a) that decreased enzyme activity and nondegradation of R proteins may also be due to nonactivation of pancreatic zymogens in an acidic pH of the intestinal juice the vitamin transported to the jejunum couples to intrinsic factor when pancreatic function is normal, and to intrinsic factor and R protein in exocrine pancreatic insufficiency. The observations made with these selected patients may explain why not all patients with exocrine pancreatic insufficiency develop imparied cobalamin absorption, and also why the malabsorption is corrected by the administration of bicarbonate in certain patients. SN - 0021-9738 UR - https://www.unboundmedicine.com/medline/citation/7400324/Cobalamin_malabsorption_due_to_nondegradation_of_R_proteins_in_the_human_intestine__Inhibited_cobalamin_absorption_in_exocrine_pancreatic_dysfunction_ L2 - https://doi.org/10.1172/JCI109873 DB - PRIME DP - Unbound Medicine ER -