Mucosal distribution of eosinophilic granulocytes within the gastrointestinal tract of horses.
ABSTRACT To establish reference values for the range of the number of eosinophils found in equine gastrointestinal mucosa and to describe the distribution of this cell within the equine gastrointestinal mucosa.
Gastrointestinal mucosal specimens from 14 adult horses euthanatized for reasons other than gastrointestinal disease.
Gastrointestinal mucosal specimens were collected and grouped according to their anatomic regions. For histologic examination slides were stained with Luna's eosinophil stain to determine eosinophil accumulation and distribution. The mucosa was divided into 5 sections for each anatomic location, and the percentage of eosinophils in each of the 5 sections relative to the total eosinophil count in all sections was determined. Additionally, the number of eosinophils per square millimeter of mucosa was calculated as a measure of the degree of eosinophil accumulation.
Lowest numbers of eosinophils were found in the stomach, and numbers increased from there to the cecum, then decreased from the ascending colon (right ventral colon, left ventral colon, pelvic flexure, left dorsal colon, and right dorsal colon) to small colon. In all gastrointestinal sections, most eosinophils were located near the muscularis mucosae and were rarely found near or on the luminal surface of the mucosa.
The distribution of eosinophils in the gastrointestinal tract of horses followed a pattern within the mucosa and between different sections of the gastrointestinal tract. The derived reference values and distribution data could be used to detect changes in eosinophil response in the equine gastrointestinal mucosa caused by diseases states.
Dataset: In vitro and in vivo responses of mucosa from the large colon of horses to ischemia and reperfusion[show abstract] [hide abstract]
ABSTRACT: S trangulating volvulus of the large colon is one of the most severe forms of colic and can account for 11% to 27% of horses requiring surgical correction of colic in referral hospitals. 1–3 Survival after surgery for correction of large colon volvulus is dependent on the degree of ischemic injury to the colon and severity of the systemic response. The survival rate without surgi-cal resection has been reported to be as low as 34.7%, 2 but resection improved the survival rate of affected horses in 2 studies (57.7% 4 and 74%, 5 respectively). In most horses that undergo colon resection, some isch-emic tissue remains. Thus, survival in these horses can Objective—To induce ischemia and reperfusion injury in the large colon mucosa of horses in vivo and evaluate the recovery and effects of components of an organ transplant solution on mucosal recovery in vitro. Animals—6 healthy horses. Procedures—Horses were anesthetized, and ischemia was induced for 60 minutes in the pelvic flexure, which was followed by reperfusion for 240 minutes. Ischemic (n = 4 horses), reperfused (6), and adjacent control (6) colonic mucosae were isolated for in vitro testing and histologic examinations. Tissues were mounted in Ussing chambers with plain Krebs Ringer bicarbonate (KRB), KRB with N-acetylcysteine (NAC), or KRB with a modified or-gan transplant solution (MOTS). Transepithelial electrical resistance (TER) and mannitol flux were used to assess mucosal integrity. Data were analyzed by use of ANOVA and Kruskal-Wallis tests. Results—The TER in reperfused tissues was similar to the TER in control tissues and great-er than the TER in ischemic tissues, which was consistent with morphological evidence of recovery in reperfused tissues. Mannitol flux was greater in ischemic tissues than in reperfused tissues. The TER and mannitol flux were not significantly affected by incubation of mucosa with NAC or MOTS. Conclusions and Clinical Relevance—Ischemia induced during the brief period allowed rapid mucosal repair and complete recovery of tissue barrier properties during reperfusion. Therefore, reperfusion injury was not observed for this method of ischemic damage in equine colonic mucosa. (Am J Vet Res 2011;72:982–989) be correlated with loss of the epithelial barrier in the remnant portion, which allows transmucosal leakage of endotoxins, bacterial chemotactic peptides, and bac-teria. 6 Therefore, rapid repair of the ischemic-injured epithelium is crucial to recovery of a horse after large colon volvulus but could be impaired by reperfusion injury. 7–12 The biochemical pathway responsible for reperfu-sion injury starts with accumulation of products that build up during ischemia and ROS generated on reper-fusion. 7–10 Neutrophil infiltration is a time-dependent process that occurs mostly during the reperfusion peri-od, 8,11 and activation of these cells results in degranula-tion and additional release of inflammatory mediators, such as cytokines, ROS, proteases, and other regulatory proteins. 12 Although ischemia is a major