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Biomedical subjects

J P Webb

Publications and source records attributed to J P Webb.

34 records · Page 2Linked to original sources
PubMed1975

A study of relations between the absorption of amino acids, dipeptides, water and electrolytes in the normal human jejunum.

1. A double-lumen perfusion technique was used to study the effect of a wide range of concentrations of the dipeptide glycyl-L-alanine and its constituent amino acids on water and electrolyte absorption from iso-osmotic solutions in the upper jejunum of normal human subjects. 2. There was no significant absorption of water and electrolytes from sodium chloride solution (150 mmol/l) but the presence of the dipeptide or its constituent amino acids stimulated water and electrolyte absorption. 3. Water absorption reached a peak at increasing amino acid and dipeptide concentrations and then tailed off. Our data suggest that the tailing off is not solely due to the diminished sodium content of the solutions. 4. During perfusion of the dipeptide-sodium chloride and amino acid-sodium chloride solutions solute and water were absorbed as an iso-osmotic solution. Analysis of the results indicates that this could occur at high dipeptide concentrations only if the majority of the dipeptide enters the cell intact.

Adult↗
PubMed1975

Ileal function in patients with untreated adult coeliac disease.

A double-lumen perfusion technique has been used to investigate jejunal and ileal absorption of glucose, water, and electrolytes in a group of patients with untreated adult coeliac disease. Correct positioning of the tube was confirmed by measuring the differential jejunal and ileal handling of bicarbonate. Eight control subjects and eight patients with coeliac disease were perfused with an isotonic electrolyte solution containing 50 mM glucose and 25 mM bicarbonate. The group of coeliac patients had impaired jejunal absorption of glucose (P less than 0.001), water (P less than 0.01), sodium (P less than 0.02), and chloride (P greater than 0.05) compared with the control group. In contrast the group of coeliac patients had normal ileal glucose and water absorption and increased ileal sodium (P greater than 0.01) and chloride (P greater than 0.05) absorption compared with the controls. Evidence for ileal adaptation was found in three individual patients who had absorptive values outside 2SD of the normal mean. The results indicate that the distal small intestine in coeliac disease has the ability to adopt to the damage and loss of absorptive capacity in the proximal small intestine.

Adolescent↗
PubMed1974

Functional differentiation of human jejunum and ileum: a comparison of the handling of glucose, peptides, and amino acids.

The characteristics of glucose, glycine, L-alanine, and glycyl-L-alanine absorption from the jejunum and ileum have been compared in normal human subjects. A perfusion technique has been used, and correct positioning of the perfusion tube has been confirmed by measuring the differential jejunal and ileal handling of bicarbonate. Glucose and glycine were absorbed faster from the jejunum than from the ileum of all subjects studied, and L-alanine was absorbed faster from the jejunum than from the ileum in five out of six subjects studied. In contrast, the dipeptide glycyl-L-alanine was absorbed at comparable rates from the jejunum and ileum. Higher concentrations of free amino acids were detected in the luminal contents aspirated during the ileal dipeptide perfusions.These results emphasize the importance of oligopeptide transport in the absorption of protein digestion products, especially in the human ileum, and the practical implications of these findings are discussed.

Adult↗