Previous data in our lab demonstrated an inability to induce oral tolerance when using a feeding needle gavage for 14 days. Given that the upper gastrointestinal (GI) tract is the site of antigen introduction, and the interplay between immune cells of the mucosal tissues, we questioned if inflammation in this tissue, induced by physical trauma, would affect oral tolerance induction. We performed studies on Balb/c mice using a needle gavage or syringe feeding method followed by doses of the immunogenic protein ovalbumin (OVA) to induce tolerance. Immunohistochemistry was used to assess inflammation in esophageal tissues and to correlate with an ability or inability to induce tolerance. Non-cellular alterations within the tissue were also assessed using a pathology grading score. Although fluctuations in cell populations were observed in both the syringe and gavage treated mice, the needle gavage caused significant noncellular damage to esophageal mucosal tissue, which is the most likely cause of failed tolerance induction to the OVA. / Department of Biology

Thesis (Ph. D.)--University of New South Wales, 2004. / Title from PDF title page (viewed on Mar. 25, 2006). Includes bibliographical references (p. 264-286).

<p>Drugs and other foreign compounds must often be metabolised before they can be excreted from the body. One enzyme system that is responsible for this is the cytochrome P450 gene family (CYP). In this thesis, new sensitive molecular techniques have been used to study the human gene expression of some CYP enzymes, as well as the P-glycoprotein transporter (P-gp). The aim was to evaluate whether tissues other than the liver, e.g. the blood, could be used to assess an individual's drug metabolic capacity. Another aim was to investigate the gene expression in relation to the liver transplant process and a third aim was to evaluate the expression in gastrointestinal mucosa in both normal and inflamed mucosa.</p><p>We evaluated the CYP gene expression in paired specimens of liver and blood but found no correlation in the expression patterns of these two tissues. Instead, we found the opposite pattern, where, for example, CYP1B1 had the highest expression in the blood but the lowest in the liver and CYP2E1 was the enzyme with the highest expression in the liver. In an investigation of the expression of four different CYP enzymes and P-gp in liver transplants before and during the first year after transplantation, we found that the levels of all the CYP enzymes but not P-gp increased with time. We also found that the expression of CYP3A4 was inversely related to the normalised plasma levels of the immunosuppressive drugs cyclosporine and tacrolimus.</p><p>In the gastrointestinal tract, CYP2E1 was the enzyme with the highest mRNA expression compared with CYP3A4, CYP3A5 and the transporter P-gp. CYP3A4 has its highest expression in the duodenum compared with the expression in the stomach and the colon. CYP3A5 is expressed at a higher level than CYP3A4 in the colon. P-gp expression levels increase through the gastrointestinal tract to the left colon. Gene expression levels of CYP2E1 and CYP3A4 decrease in severely inflamed rectal mucosa. </p><p>In conclusion, this is a sensitive method for studying gene activity in a clinical situation, even though at this point we are not able to use blood or gastrointestinal mucosa as “surrogate” tissue to estimate an individual’s drug metabolic capacity. The studies in liver transplants and gastrointestinal mucosa are unique in that the gene expression is investigated during a clinical course of events.</p>

Drugs and other foreign compounds must often be metabolised before they can be excreted from the body. One enzyme system that is responsible for this is the cytochrome P450 gene family (CYP). In this thesis, new sensitive molecular techniques have been used to study the human gene expression of some CYP enzymes, as well as the P-glycoprotein transporter (P-gp). The aim was to evaluate whether tissues other than the liver, e.g. the blood, could be used to assess an individual's drug metabolic capacity. Another aim was to investigate the gene expression in relation to the liver transplant process and a third aim was to evaluate the expression in gastrointestinal mucosa in both normal and inflamed mucosa. We evaluated the CYP gene expression in paired specimens of liver and blood but found no correlation in the expression patterns of these two tissues. Instead, we found the opposite pattern, where, for example, CYP1B1 had the highest expression in the blood but the lowest in the liver and CYP2E1 was the enzyme with the highest expression in the liver. In an investigation of the expression of four different CYP enzymes and P-gp in liver transplants before and during the first year after transplantation, we found that the levels of all the CYP enzymes but not P-gp increased with time. We also found that the expression of CYP3A4 was inversely related to the normalised plasma levels of the immunosuppressive drugs cyclosporine and tacrolimus. In the gastrointestinal tract, CYP2E1 was the enzyme with the highest mRNA expression compared with CYP3A4, CYP3A5 and the transporter P-gp. CYP3A4 has its highest expression in the duodenum compared with the expression in the stomach and the colon. CYP3A5 is expressed at a higher level than CYP3A4 in the colon. P-gp expression levels increase through the gastrointestinal tract to the left colon. Gene expression levels of CYP2E1 and CYP3A4 decrease in severely inflamed rectal mucosa. In conclusion, this is a sensitive method for studying gene activity in a clinical situation, even though at this point we are not able to use blood or gastrointestinal mucosa as “surrogate” tissue to estimate an individual’s drug metabolic capacity. The studies in liver transplants and gastrointestinal mucosa are unique in that the gene expression is investigated during a clinical course of events.