Date of Award
Animal, Dairy, and Veterinary Sciences
Cryptosporidium parvum, a protozoan parasite infecting epithelial cells lining the intestinal tract of animals and humans, causes fulminate diarrhea and malabsorption of essential nutrients following damage to the cellular brush border. The present study was undertaken to evaluate the use of a pentose sugar (D-xylose) in a standardized tolerance test as an indicator of malabsorption due to cryptosporidiosis in the dexamethasone (DEX)-immunosuppressed adult C57BL/6N mouse model. One group containing 14 experimental mice (in addition to appropriate control groups) was immunosuppressed using daily intraperitoneal injections of DEX (125 μg/mouse). On day 7 postimmunosuppression, mice were inoculated orally with 104 C. parvum oocysts/mouse. Approximately 1 month postinoculation, feces from individual mice were checked for oocyst shedding using an indirect immunofluorescent assay to confirm patent infections. After 24 hours of fasting, infected mice were administered Dxylose (2.5 mg/ g body weight) by gavage. Mice were killed at either 45 or 90 minutes post-D-xylose administration, blood was collected from the chest cavity, and the serum was harvested. Sections of the proximal duodenum and distal ileum of each mouse were histologically prepared for quantitation of C. parvum using brightfield microscopy. Serum was analyzed with a spectrophotometer (520 nm) by employing a calorimetric reaction as a measure of the absorptive capacity of D-xylose in the small intestine of C. parvum-infected mice. Statistical analysis revealed no significant correlation between the number of parasites present and intestinal absorption of D-xylose. However, administration of DEX was positively correlated to D-xylose absorption. These findings indicate that the xylose tolerance test is inappropriate in the adult C57BL/6N mouse model for evaluating malabsorption due to cryptosporidiosis in the presence of
Evans, James A., "The Use of the Xylose Tolerance Test as an Indicator of Malabsorption in Cryptosporidiosis" (1996). Undergraduate Honors Capstone Projects. 300.
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Mark C. Healey