K W Smithson | PubMed Health

PubMed1978

Food sensitivity in reflux esophagitis.

We examined 66 patients with pain of possible esophageal origin for sensitivity to intraesophageal infusions of coffee, orange juice, spicy tomato drink, or HCl of varying concentrations as an addendum to their acid infusion (Bernstein) tests. Compared to Berstein-negative subjects, acid-sensitive patients were sensitive to infusion of coffee (P less than 0.01), orange juice (P less than 0.001), and tomato drink (P less than 0.001). Patients were largely insensitive to HCl solutions with a titratable acidity of 1 mEq per liter or less, less than the least acidic food solution tested. However, Berstein-positive patients were still highly sensitive to infusions of coffee, orange juice, and tomato drink adjusted to pH 7 (P less than 0.001). Patients were unable to differentiate symptoms caused by acid or food infusions, and solutions did not differ in the duration of infusion needed either to cause symptoms or to relieve them by saline. We conclude that the pain of esophagitis is nonspecific and can be precipitated by variety of seemingly unrelated substances.

Adult↗

PubMed1977

Intestinal assimilation of a tetrapeptide in the rat. Obligate function of brush border aminopeptidase.

The small intestine is capable of taking up peptide nutrients of two or three amino acid residues, but the mechanism of intestinal assimilation of larger oligopeptides has not been established. The amino-oligopeptidase of the intestinal brush border possesses high specificity for oligopeptides having bulky side chains and is a candidate for a crucial role in the overall assimilation of dietary protein. Rat jejunum was used for in vitro gut sac and in vivo perfusion experiments with Gly-l-Leu-Gly-Gly (2 mM) as the test substrate with analysis of parent peptide and products by automatic ion-exchange chromatography. In these experiments, the tetrapeptide disappeared rapidly from the test solution (20 mumol/s per cm(2) in vitro; 17 mumol/s per cm(2) in vivo) by sequential removal of amino acid residues from the N-terminus to yield amino acids and the C-terminal dipeptide. In gut sac experiments, 61-100% of these products of hydrolysis appeared in the incubation medium and the remainder in the tissue. In contrast, only small amounts of hydrolytic products were found within intestinal lumen in vivo.Gly-l-Pro (10 mM), a peptide known to be transported intact but not to be hydrolyzed by the brush border aminopeptidase, failed to inhibit Gly-l-Leu-Gly-Gly disappearance suggesting that the tetrapeptide does not utilize the known intact transport mechanism. Hypoxic conditions (N(2) atmosphere) in vitro markedly inhibited transport of glucose, leucine, and Gly-Gly but failed to impair Gly-l-Leu-Gly-Gly disappearance suggesting that the first step in assimilation of the tetrapeptide does not involve a transport process. Disappearance of the tetrapeptide was completely blocked by l-leucyl-beta-naphthylamide (10 mM), a specific substrate for brush border aminopeptidase and by the phthalimido derivative of l-leucine bromomethyl ketone, a potent peptidase inhibitor. Hence, the amino-oligopeptidase at the intestinal surface appears to be essential for the initial stages of assimilation of this model tetrapeptide.

Aminopeptidases↗