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PubMed1977

Intestinal immune response to E. coli antigens in the germ-free chicken.

The secretory intestinal immune response to live and heat-inactivated E. coli 02 has been studied in young germ-free chicks. A response to live organisms was evident from an infiltration of the intestinal mucosa with IgA and IgM immunoglobulin-producing cells (IPC). Antibody associated with both immunoglobulin classes which was specific for E. coli 02 was demonstrated in saline extracts of contents from the small intestine. Repeated oral immunization with heat-killed E. coli 02 failed to stimulate serum or intestinal antibody. This finding reflected the complete absence of IPC within the intestinal mucosa of these birds. The IPC profile of unimmunized germ-free chicks was identical to that seen in chicks orally immunized with inactivated E. coli. An interesting feature of all gnotobiotic birds was a considerable elevation of serum IgM levels, compared to those of conventional birds, which was unassociated with immunization procedures. Serum IgG and IgA levels in gnotobiotes were much lower than those in the serum of conventional birds of comparable age. Studies on the fate of orally administered antigen using radiolabelled E. coli endotoxin indicated that a proportion remained intact as far down the intestinal tract as the caecum. However, unaccountably high levels of low mol. wt antigen in the faeces suggested degradation, intestinal absorption and subsequent excretion of endotoxin fragments in the urine. The differences between the avian response and that observed in mammals are discussed in relation to the comparative roles of Peyer's patches and the bursa of Fabricius in initiating intestinal immununity.

Animals↗
PubMed1977

Studies on translocation of immunoglobulins across intestinal epithelium. IV. Evidence for binding of IgA and IgM to secretory component in intestinal epithelium.

We conducted studies concerning the issue of whether secretory component (SC) is a specific receptor on intestinal epithelial cells for IgA and IgM. Initially, frozen sections of human intestinal mucosa were incubated with dimeric monoclonal human IgA, conjugated to horseradish peroxidase; adjacent sections were reacted with peroxidase-conjugated antibodies to SC. The conjugated IgA and anti-SC bound to similar sites in the epithelium, that is to basolateral margins and supranuclear cytoplasm of columnar epithelial cells, principally in gland crypts. In subsequent tests of binding specificity, binding of the dimeric IgA conjugate was inhibited by pretreating the tissues with unconjugated dimeric IgA or 19S IgM, pretreating the tissues with unconjugated antibodies to SC, or preincubating the dimeric IgA conjugate with free SC. Binding was not inhibited or only partially inhibited by pretreating the tissues with monomeric IgA or IgG, pretreating the tissues with antibodies to human or heterologous immunoglobulins, or preincubating the dimeric IgA conjugate with 11S secretory colostral IgA. The findings indicate that dimeric IgA and 19S IgM are capable of binding in vitro to specific sites on intestinal epithelial cells, most likely to SC. This supports the hypothesis that transport of these immunoglobulins into intestinal fluids involves their combination with SC in the epithelium.

Binding Sites, Antibody↗
PubMed1986

Acceleration of the elimination of tenoxicam by cholestyramine in the dog.

Two commonly used adsorbents, activated charcoal and cholestyramine, were evaluated in vitro for their ability to adsorb the nonsteroidal anti-inflammatory drug tenoxicam and in vivo for their use in influencing the elimination kinetics of this drug. The Langmuir binding isotherms determined in buffer solutions at pH 7.5 indicated a much greater adsorption capacity of cholestyramine (1.63 g of drug per g of resin) than of charcoal (0.18 g/g of adsorbent) for the acidic drug with a pKa of 5.3. When single i.v. tenoxicam administrations to dogs were followed by multiple p.o. cholestyramine doses the elimination rate of the drug was accelerated drastically. Due to an increased total body clearance (0.65 vs. 0.13 liters/hr), the elimination half-life was reduced from a median base-line value of 31 to 5.4 hr and the mean residence time of drug in the body was decreased from 41 to 7.9 hr. In contrast to cholestyramine, charcoal hardly increased the rate of elimination of tenoxicam over the base-line values determined in the same animals. Inasmuch as these results were similar in all three animals investigated and because the study design precluded an influence of the treatment sequence, it is concluded that cholestyramine efficiently sequesters intestinally secreted tenoxicam and can thereby accelerate drug elimination from the body.

Administration, Oral↗
PubMed1986

[Morphofunctional status of the small intestine after disruption of its extrinsic innervation].

Within 6 months after decentralization of the rat and dog intestine, signs of reinnervation appear. Hypersecretion of the intestine juice, a decrease in the acetylcholine and noradrenaline contents, reduction of the invertase and alkaline phosphatase activity in the juice and homogenate of the small intestine occur during first weeks. The activating effect of the food on transmitter-enzymatic processes weakens whereas activity of the enteral nervous system is enhanced. The data obtained are significant for intestine transplantation research.

Acetylcholine↗
PubMed1985

A reappraisal of upper gastrointestinal response to low-dose glucagon.

Although glucagon is the most commonly used pharmacologic agent for gastrointestinal studies, its exact effects on upper gastrointestinal examinations have not been properly elucidated. A large study by our group did redemonstrate glucagon's significant effect on gastrointestinal motility. However, gastric distention and coating are not improved by glucagon, nor does it have a predictable effect on gastric emptying. Duodenal visualization does appear to be enhanced by the drug. Patient age, weight, and sex are not significant factors in glucagon's response, although they are variables that have an effect on UGI examinations. This article will review physiologic considerations in upper gastrointestinal examinations, with emphasis on glucagon's pharmacodynamics.

Age Factors↗
PubMedDate not supplied

[Assessment of the in vitro digestibility of dietary proteins and of the degree of the breakdown of their antigenic structures by using polyenzyme systems].

A comparative assessment was made of the digestion of bovine serum albumin (BSA), chicken ovalbumin (OVA), and casein by means of the gastric juice--duodenal contents floccular gel structures (FGS) system and a four-enzymic system including trypsin, chymotrypsin, peptidase, and bacterial protease preparations. Decomposition of the BSA and OVA antigenic structures with the use of the two systems was also studied. Significant differences in BSA and OVA digestion by the gastric juice--FGS system were detected both with respect to amino nitrogen content and to the degree of their antigenic structure decomposition, whereas no such differences were observed when the four-enzymic system was used. The systems most accurately simulating the 'proteolytic conveyer' conditions of the gastrointestinal tract are preferable for the studies. The developed method is recommended for use in comparative assessment of the nutrient protein sensitizing properties.

Animals↗