Search PubMed⌕ Search

Biomedical subjects

M H Sleisenger

Publications and source records attributed to M H Sleisenger.

At least 19 recordsLinked to original sources
PubMed1979

Protein digestion and absorption in man. Normal mechanisms and protein-energy malnutrition.

Protein is an essential nutrient normally assimilated in an efficient manner following the action of gastric, pancreatic and small intestinal enzymes. After hydrolysis, protein digestion products in the form of amino acids and small peptides undergo mucosal uptake by distinct transport mechanisms. Although gastric and pancreatic enzymes are important, the small intestine appears to be the critical rate-limiting tissue in this process. Impaired intake, assimilation or excessive enteric protein loss may occur with several diseases leading to protein-energy malnutrition. Although the clinical and laboratory features of this condition are nonspecific and wide ranging in spectrum, their presence may provide a clue to underlying disease and serve as an index of patient nutritional status. Disease of the exocrine pancreas or small intestine may cause significant protein-energy malnutrition which, in turn, can cause major structural and functional abnormalities in these tissues.

Dietary Proteins↗
PubMed1979

Gastric, pancreatic, and biliary secretion and the rate of gastric emptying after parietal cell vagotomy.

We compared the gastric, pancreatic, and biliary secretory responses to a liquid test meal and the rates of gastric emptying of liquid and solid test meals in six patients at least 1 year after parietal cell vagotomy with eight unoperated subjects, one with duodenal ulcer disease and seven normal control subjects. Parietal cell vagotomy decreased gastric acid secretion to one third of normal, but total trypsin and bile salt secretion during the first 150 postcibal minutes were normal. The liquid test meal emptied from the stomach faster after parietal cell vagotomy, the pattern of emptying being exponential in the vagotomy patients and linear in the normal subjects. The rate of gastric emptying of a liquid meal, although faster than normal, was less precipitous after parietal cell vagotomy than after truncal vagotomy plus drainage or subtotal gastrectomy, and trypsin and bile salt concentrations were not diluted to abnormal levels, as occurs after these other procedures. Furthermore, emptying and dispersion of solid food remained normal after parietal cell vagotomy. These findings probably explain, at least in part, the decreased incidence of postprandial dumping and diarrhea that accompanies parietal cell vagotomy compared with the other popular operations for duodenal ulcer.

Adult↗
PubMed1979

Zymogram studies of human intestinal brush border and cytoplasmic peptidases.

Zymogram studies of peptide hydrolases from the human intestinal brush border and cytoplasmic fractions produced multiple bands--that is, up to seven--while the brush border membrane produced only a single band of enzyme activity. With all of the substrates tested except L-leucyl-L-leucyl-L-leucine, a band having anodic mobility identical with that produced by the brush border enzymes was produced by the cytoplasmic enzymes. With L-trileucine as a substrate, no overlapping band was produced. This band in the cytoplasmic fraction was heat sensitive, while that in the brush border fraction was not. Thus it would appear that there is a single human intestinal brush border peptide hydrolase capable of hydrolysing a variety of di- and tri-peptides. This peptide hydrolases of the brush border and the cytoplasmic fraction of human intestine are distinct.

Cell Membrane↗
PubMed1979

Comparison of oral feeding of peptide and amino acid meals to normal human subjects.

Intestinal perfusion studies performed in man have suggested that amino acid nitrogen may be absorbed more rapidly from peptides than free amino acids. The aim of the present study was to compare the effects of the oral administration of peptides and free amino acids. Two isonitrogenous liquid test meals, one containing 50 g of a partial enzymic hydrolysate of fish protein in which approximately 80% of the nitrogen content was present as small peptides (peptide meal), and the other a mixture of free amino acids (amino acid meal) the composition and molar pattern of which simulated that of the peptide meal, were administered on separate occasions to six normal subjects intubated with a triple lumen tube. Both meals contained the reference marker polyethylene glycol. Fractional absorption of amino acid residues one and two hours after ingestion of the two meals was similar at three intestinal locations situated 120, 160, and 200 cm from the mouth of each subject, and at two hours 73.8% and 72.0% of the amino acid residues had been absorbed respectively by the time the contents of the peptide and amino acid meals reached the middle sampling port of the tube. The total sum of individual amino acid increments in plasma was significantly greater 30 minutes (p < 0.025) and one hour (p < 0.05) after ingestion of the peptide than amino acid meals. By three hours the total area under the two plasma curves was similar. Normal human subjects thus appeared to be capable of assimilating orally administered mixtures of peptides and free amino acids with equal efficiency. Secretion of fluid into the lumen of the upper small intestine, assessed by reference to dilution of the polyethylene glycol, was less after ingestion of the peptide meal. In clinical situations characterised by fluid and electrolyte malabsorption consideration might be given to using small peptides rather than free amino acids as the nitrogen source in nutritional diets.

Adult↗
PubMed1978

The role of bile acids in determining ileal flow rates in normal subjects and following ileostomy.

The possibility that intraluminal bile acid concentrations contribute to fluid and electrolyte movement in the normal ileum, and that alterations following ileostomy aid ileostomy adaptation, has been investigated. A significant correlation between the concentration of chenodeoxycholic acid plus deoxycholic acid, and volume flow through the normal ileum and ileostomy effluent volume was found. However, the regression lines relating bile acid concentrations to volume flow in the two groups were clearly separated, indication that factors besides altered bile acid metabolism are predominant in ileostomy adaptation.

Adaptation, Physiological↗
PubMed1977

Amino acid concentrations in portal venous plasma during absorption from the small intestine of the guinea pig of an amino acid mixture simulating casein and a partial enzymic hydrolysate of casein.

1. The characteristics of absorption of individual amino acids from amino acid mixtures simulating casein and from enzymic hydrolysates of casein containing oligopeptides as well as free amino acids are known to be different. The differences, which are attributable to mucosal uptake of small peptides, involve more rapid absorption from the enzymic hydrolysates of certain amino acids which are relatively slowly absorbed from the amino acid mixtures. This could lead to more effective utilization of amino acids from the enzymic hydrolysates than from the amino acid mixtures. 2. To obtain further information bearing on this hypothesis, we have used a recently developed technique for portal cannulation in the guinea pig to make a preliminary investigation of amino acid concentrations in the portal venous plasma at intervals after the infusion into the duodenum of equivalent amounts of (a) an amino acid mixture simulating casein and (b) a partial enzymic (papain followed by kidney peptidases) hydrolysate of casein, the two preparations being infused in separate experiments. 3. For some amino acids, such as leucine, isoleucine, valine, phenylalanine and lysine, the curves after the enzymic hydrolysate were fairly similar to the corresponding curves after the amino acid mixture, though usually slightly lower. With other amino acids, the curves after the enzymic hydrolysate were very much lower than the corresponding curves after the amino acid mixture. With serine, glutamine, proline and glycine this discrepancy was particularly great. 4. The results cannot yet be fully explained, but their main features are explicable by the hypothesis that the lower amino acid concentrations in portal plasma after the enzymic hydrolysate are the result of entry of amino acids into the portal blood in peptide form, in which they would not be detectable by the analytical technique employed, and possibly also of more rapid clearance of amino acids from the blood during absorption of this preparation.

Amino Acids↗
PubMed1977

Malabsorption.

Explore the source record for details and available documents.

Biopsy↗
PubMed1976

Evidence for a single common carrier for uptake of a dipeptide and a tripeptide by hamster jejunum in vitro.

This paper describes an investigation of whether a dipeptide and a tripeptide were taken up by hamster jejunum by the same transport system, or whether there was evidence of uptake by more than one transport system. The work was carried out with rings of everted hamster jejunum in vitro, under conditions of influx, using the "model" peptides glycylsarcosine, glycylsarcosylsarcosine, and glycylsarcosylsarcosylsarcosine. These peptides are all exceptionally resistant to hydrolysis, appearing intact in the rings, and the di- and tripeptide have previously been shown to be concentrated in the rings by active transport. The results showed that influx of glycylsarcosine was inhibited by glycylsarcosylsarcosine in a competitive way, and that each of the peptides was capable of causing virtually complete inhibition of influx of the other. Glycylsarcosylsarcosylsarcosine had no effect on influx of glycylsarcosine or of glycylsarcosylsarcosine. It was concluded that although the existence of multiple transport systems shared by both glycylsarcosine and glycylsarcosylsarcosine could not be ruled out, the simplest hypothesis was that both the dipeptide and the tripeptide shared a single common carrier for uptake. The tetrapeptide glycylsarcosylsarcosylsarcosine was apparently not transported by this carrier, in agreement with previous results. The possible effects of the "unstirred layer" were taken into account in considering the results and are discussed. They do not alter the conclusions reached.

Animals↗