intrinsic-factor and Exocrine-Pancreatic-Insufficiency

Topics: Animals; Bile; Calcium; Exocrine Pancreatic Insufficiency; Humans; Intestinal Absorption; Intestinal Secretions; Intrinsic Factor; Microvilli; Pancreas; Protein Binding; Transcobalamins; Vitamin B 12

Topics: Blood Proteins; Exocrine Pancreatic Insufficiency; Humans; Intrinsic Factor; Pancreas; Peptide Hydrolases; Transcobalamins

Pancreatic proteases degrade the protein moiety of the R protein-cobalamin complex but not the intrinsic factor-cobalamin complex. Accordingly, we used these two proteins as substrates in an in vitro enzymatic assay to assess pancreatic function by incubating basal jejunal fluids with a mixture of intrinsic factor and cyano[57Co]cobalamin coupled to R-type protein and then using immunoprecipitation to determine the distribution of isotopically labeled cobalamin bound to the two proteins. With normal jejunal fluids, 91.2 (SD 6.1)% and 4.5 (SD 5.5)% of cyano[57Co]cobalamin was precipitated with antisera to intrinsic factor and anti-R protein, respectively. In the patients' jejunal fluids, the cyano[57Co]cobalamin precipitated with the respective antisera was 5.3 (SD 10.0)% and 96 (SD 6.2)%. In patients with other gastrointestinal problems, the sequestration of cobalamin was indistinguishable from that observed with the normal fluids. The clearcut discrimination this radioimmunoassay provided between abnormal and normal samples was confirmed by parallel comparative chromatographic analysis.

Topics: Chromatography, Gel; Exocrine Pancreatic Insufficiency; Humans; Ileum; Intestinal Absorption; Intestinal Secretions; Intrinsic Factor; Jejunum; Pancreas; Peptide Hydrolases; Radioimmunoassay; Transcobalamins; Vitamin B 12

It is important to understand which pancreatic function tests are available and how to interpret them when evaluating patients with malabsorption. Available direct tests are the secretin stimulation test, the Lundh test meal, and measurement of serum or fecal enzymes. Indirect tests assess pancreatic exocrine function by measuring the effect of pancreatic secretion on various nutrients. These include triglycerides labeled with carbon 14, cobalamin labeled with cobalt 57 and cobalt 58, and para-aminobenzoic acid bound to a dipeptide. Of all these tests the secretin stimulation test is the most accurate and reliable if done by experienced personnel. However, the indirect tests are simpler to do and appear to be comparable to the secretin test at detecting pancreatic exocrine insufficiency. These indirect tests are becoming clinically available and clinicians should familiarize themselves with the strengths and weaknesses of each.

Topics: 4-Aminobenzoic Acid; Amylases; Carbon Radioisotopes; Exocrine Pancreatic Insufficiency; Fats; Feces; Humans; Intrinsic Factor; Lipase; Malabsorption Syndromes; Pancreas; Pancreatic Function Tests; Pancreatin; Secretin; Triolein; Vitamin B 12

Ingested cyano[57Co]cobalamin was recovered as coupled to intrinsic factor from the jejunum of healthy humans. This vitamin-protein complex and the analogous complex from patients having exocrine pancreatic insufficiency were indistinguishable from each other in terms of molecular radius (3.30 nm), ionic nature (eight well-defined isoproteins isoelectric at pH 4.71, 4.84, 4.90, 5.13, 5.23, 5.31, 5.40 and 5.69), and antigenic structure. These findings indicate that the pancreatic proteases do not alter the intrinsic factor cobalamin complex in vivo. Purified R type protein-cyano [57Co]cobalamin complex recovered from patients with exocrine pancreatic insufficiency was similar to the analogous gastric protein in terms of molecular radius (alpha = 4.78 nm) and types of isoproteins (seven well-defined isoproteins isoelectric at pH 2.70, 3.03, 3.38, 3.74, 3.87, 4.05 and 4.20). However, this R protein complex from patients and the intrinsic factor complex from both control subjects and from patients was comprised of more of the acidic type of isoproteins, thereby supporting the notion that carbohydrate-rich isoproteins are more resistant to digestion in the intestine.

Topics: Biological Transport; Carrier Proteins; Digestion; Exocrine Pancreatic Insufficiency; Humans; Intestine, Small; Intrinsic Factor; Isoelectric Focusing; Jejunum; Transcobalamins

Topics: Alcoholism; Celiac Disease; Exocrine Pancreatic Insufficiency; Folic Acid; Folic Acid Deficiency; Gastric Mucosa; Glutamates; Humans; Ileum; Intestinal Absorption; Intrinsic Factor; Malabsorption Syndromes; Protein Binding; Transcobalamins; Vitamin B 12; Vitamin B 12 Deficiency