In this study, immunohistochemistry was used to examine the changes in the density of colonic endocrine cells - argyrophil and argentaffin cells, chromogranin A (CGA), serotonin, somatostatin and glucagon-containing cells in trinitrobenzene sulfonic acid (TNBS)-induced rat colitis. Ulcerative colitis was induced by the instillation of 10 mg of TNBS into the colonic lumen through the anus. To confirm the inducement of ulcerative colitis, the macroscopic and microscopic scores as well as the colonic myeloperoxidase (MPO) activities were monitored for 8 days after TNBS instillation in the colonic lumens. In addition, the number of argyrophil and argentaffin cells, CGA, serotonin, somatostatin and glucagon-immunoreactive cells were counted in the colonic mucosa, respectively. After TNBS instillation into the lumen of the colon from the anus in rats, increases in macroscopic and microscopic scores in the colon tissues were observed along with increases in the colonic MPO activities. Therefore, ulcerative colitis was relatively well induced by the TNBS instillations. Marked decreases in the number of colonic endocrine cells were detected in the TNBS-treated animal compared to the sham control. These results suggest that colonic endocrine cells were also disrupted by TNBS-induced ulcerative colitis.

Effects of low-flow ischemia and reperfusion of the large colon on systemic and colonic hemodynamic and metabolic variables were determined in horses. Twenty-four adult horses were randomly allocated to 3 groups: sham-operated (n = 6), 6 hours of ischemia (n = 9), and 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia was induced in groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. Heart rate, arterial blood pressures, cardiac index, pulmonary artery pressure, right atrial pressure, and colonic blood flow were monitored. Arterial, mixed-venous, and colonic venous blood gas and oximetry analyses; PCV; and blood lactate and pyruvate and plasma total protein concentrations were measured. Data were recorded, and blood samples were collected at baseline and at 30-minute intervals for 6 hours; additionally, data were collected at 185, 190, and 195 minutes (corresponding to 5, 10, and 15 minutes of reperfusion in group-3 horses). There were no differences among groups at baseline or across time for any systemic hemodynamic or metabolic variable. Colonic blood flow did not change across time in group-1 horses. Colonic blood flow significantly (P < 0.05) decreased to 20% of baseline at induction of ischemia in horses of groups 2 and 3 and remained significantly decreased throughout the ischemic period in horses of groups 2 (6 hours) and 3 (3 hours). Colonic blood flow significantly (P < 0.05) increased above baseline by 5 minutes of reperfusion in group-3 horses. Colonic oxygen delivery and oxygen consumption, and colonic venous pH, PO2, percentage saturation of hemoglobin, and oxygen content were significantly (P < 0.05) decreased within 30 minutes after induction of ischemia in horses of groups 2 and 3; colonic venous PCO2, colonic oxygen extraction ratio, and lactate and pyruvate concentrations were significantly (P < 0.05) increased by 30 minutes of ischemia. These alterations continued throughout ischemia, but within 5 minutes of reperfusion in group-3 horses, these variables either returned to baseline (pH, PCO2, lactate, pyruvate), significantly (P < 0.05) increased above baseline (PO2, oxygen content, % saturation of hemoglobin), or significantly (P < 0.05) decreased below baseline (colonic oxygen extraction ratio). Colonic oxygen consumption remained decreased during reperfusion in group-3 horses. Colonic mucosal ischemia-reperfusion injury observed in this model of ischemia was associated with local colonic hemodynamic and metabolic alterations in the presence of systemic hemodynamic and metabolic stability. Reactive hyperemia was observed at restoration of colonic blood flow in group-3 horses and persisted during reperfusion. Colonic venous metabolic alterations were corrected at reperfusion, indicating adaptation of the colon to the return of blood flow and oxygen delivery with resultant decrease in anaerobic metabolism. The early alterations in these variables may simply represent a washout of metabolic by-products.

Sixteen healthy ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocytes. Of the 16 ponies, 15 developed clinical signs of equine ehrlichial colitis. Twenty-four hours after onset of fever (rectal temperature > 38.8 degrees C), 7 ponies were treated with 25 mg of erythromycin stearate/kg of body weight and 10 mg of rifampin/kg, given orally every 12 hours for 5 days. The remaining 8 ill ponies served as nontreated controls. All ponies were observed for progression of clinical signs typical of equine ehrlichial colitis. Within 12 hours of initiation of treatment, 4 of the 7 treated ponies had rectal temperature < 38.4 C and, within 24 hours, 6 of the 7 ponies had rectal temperature < 38.3C. In contrast, all control ponies had rectal temperature > 39.2 C at 24 hours (P < 0.05). Of the 7 treated ponies, 4 no longer had signs of mental depression after the second day of treatment, and only 1 of the 7 ponies had mild signs of depression after the third day of treatment. In contrast, control ponies had high mental depression score during the observation period (P < 0.05). Feed intake improved in ponies of the treatment group, with feed intake of 4 of the 7 ponies returning to normal; the other 3 ponies were only mildly anorectic by the second day of treatment. Control ponies progressively decreased their feed intake during the observation period (P < 0.05). One control pony and 2 treated ponies developed diarrhea before the treatment/observation period began. Only 1 treated pony developed diarrhea after treatment began. Of the 8 control ponies, 7 developed diarrhea. Profound decrease in borborygmal sounds with silent periods lasting longer than 3 minutes was observed in 7 of the 8 control ponies. Only 1 of the 7 treated ponies had such profound decrease in borborygmi (P < 0.05). The decrease in borborygmal sounds progressed in the control ponies during the observation period. None of the treated ponies continued to have decreased borborygmi after treatment day 2 (P < 0.05). Of the 8 control ponies, 2 were euthanatized; all treated ponies survived. In survivors, signs lasted 8 to 17 (mean, 10) days in control ponies but only 1 to 5 (mean, 2.9) days in treated ponies.

Forty 3- to 17-week old domestic ferrets, including 2 gnotobiotes, were inoculated orally and/or rectally with 10(6), to 10(9) colony-forming units of 1 or more of 4 strains of Campylobacter jejuni, 3 of mink and 1 of human origin. Feeding or gavage of any of the 4 strains, in milk or broth, with or without preinoculation sodium bicarbonate treatment to neutralize stomach acid, induced colonization in 38/40 ferrets; diarrhea lasted 2 to 4 days in conventional kits, 6 days in gnotobiotes. Bacteremia was detected in 4 of 18 tested, 2 to 5 days after inoculation. Two strains caused no more severe disease or prolonged colonization after 3 serial IV passages in kits than they did before passage. Multiple inoculations with a given strain resulted in progressively briefer colonization and milder disease, but subsequent inoculation with a different strain induced colonization and gastrointestinal disease similar to a primary infection. Five kits inoculated rectally after 4 previous homologous inoculations were resistant to colonization as well as to disease. Agglutinin titers of ferrets inoculated orally or rectally once were low or undetectable, but increased in response to repeated inoculation. Pretreatment with a 1% formalin enema caused mild colon irritation without clinical or histologic evidence of proliferative colitis in ferrets concurrently inoculated orally and/or rectally, whether or not they had preexisting antibodies to any strain of C jejuni. Histologic examination of tissues revealed leukocytic infiltration of intestinal lamina propria in 29 of 35 infected kits and 5 of 8 noninfected controls, and cryptosporidiosis in 5 infected kits plus 1 control. Examination of silver-stained sections of intestine from 15 infected ferrets revealed Campylobacter-like organisms on the surface of, but never inside, epithelial cells. The lack of characteristic gross or histologic lesions suggested that C jejuni is not, by itself, responsible for proliferative colitis in ferrets.

Effects of low-flow ischemia and reperfusion of the large colon on mucosal architecture were determined in horses. Twenty-four adult horses were randomly allocated to 3 groups: sham-operated (n = 6), 6 hours of ischemia (n = 9), and 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline values. Systemic hemodynamic and metabolic variables were maintained constant and in a normal physiologic range. Full-thickness biopsy specimens were obtained from the left ventral colon for histomorphologic and morphometric examination at baseline and at 30-minute intervals for 6 hours; additional biopsy specimens were collected at 185, 190, and 195 minutes (corresponding to 5-, 10-, and 15-minute periods of reperfusion in group-3 horses). There were no differences among groups at baseline or across time in group-1 horses for any of the histopathologic variables. There were significant (P < 0.05) increases in percentage of surface mucosal disruption, estimated and measured percentage depth of mucosal loss, mucosal hemorrhage, mucosal edema, and cellular debris index during 0 hour to 3 hours, compared with baseline, and from 3 hours to 6 hours, compared with 3 hours in horses of groups 2 and 3. Estimated percentage depth of mucosal loss and cellular debris index were significantly (P < 0.05) greater in group-3 horses, compared with group-2 horses during the interval from 3 to 6 hours. There were trends toward greater percentage of surface mucosal disruption and mucosal edema during the early phase of reperfusion (3 to 4 hours) and greater mucosal hemorrhage, measured percentage depth of mucosal loss, and mucosal interstitial-to-crypt ratio during the late phase (4 to 6 hours) of reperfusion in group-3 horses vs group-2 horses. Reestablishment of colonic arterial blood flow after low-flow ischemia caused greater mucosal injury than did a comparable period of continued ischemia. Thus, reperfusion injury was detected in the large colon of horses after low-flow arterial ischemia. The serial mucosal alterations that developed in the colon were comparable in horses of groups 2 and 3; however, reperfusion exacerbated colonic mucosal injury.

Histomorphologic/morphometric evaluation, leukocyte scintigraphy, and myeloperoxidase activity were used to determine whether neutrophils accumulate in the large colon of horses during low-flow ischemia and reperfusion. Twenty-four adult horses were assigned to 1 of 3 groups: group 1, sham-operated (n = 6); group 2, 6 hours of ischemia (n = 9); and group 3, 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia of the large colon was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. Radiolabeled (99mTc) autogenous neutrophils were injected at 175 minutes, which corresponded to 5 minutes prior to reperfusion in group-3 horses. Full-thickness biopsy specimens of the left ventral colon were collected at baseline and at 30-minute intervals for 6 hours; a portion of the biopsy specimen was placed in formalin for histologic examination, and the remainder was used to measure mucosal radioactivity and myeloperoxidase activity. There were no differences in baseline mucosal neutrophil index, mucosal neutrophil numbers, submucosal venular neutrophil numbers, mucosal radioactivity, or mucosal myeloperoxidase activity among groups, or over time in group-1 horses. Neutrophils accumulated in the colonic mucosa during ischemia and further increased at reperfusion, as indicated by neutrophil index (morphology) and mucosal neutrophil numbers (morphometry); mucosal neutrophil index was significantly (P < 0.05) greater in group-3 horses during reperfusion than at the corresponding periods of ischemia in group-2 horses. Neutrophil numbers were significantly (P < 0.05) increased in submucosal venules at 10 minutes of reperfusion in group-3 horses and were significantly (P < 0.05) greater in group-3 than in group-2 horses during the interval from 3 to 6 hours. Mucosal radioactivity significantly (P < 0.05) increased at reperfusion in group-3 horses; there was a trend (P = 0.076) toward greater mucosal radioactivity in group-3, compared with group-2 horses, throughout the 3- to 6-hour interval. There were no differences in mucosal myeloperoxidase activity among or within any of the 3 groups over time. Neutrophils accumulated in the large colon of horses during low-flow ischemia and reperfusion. Neutrophil infiltration was detected by histologic examination and leukocyte scintigraphy, but not by measurement of myeloperoxidase activity. The accumulation of neutrophils during ischemia and the further neutrophil infiltration during reperfusion indicate that neutrophils may contribute to reperfusion injury of the large colon.

Eighteen ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocyte cells. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 9 ponies were treated with oxytetracycline (6.6 mg/kg of body weight, IV, q 24 h) for 5 days. The remaining 9 ponies served as infected nontreated controls. Mean scores of the following variables were not significantly different between groups on the day treatment was begun: rectal temperature, diarrhea, borborygmal sounds, feed intake, mental attitude, and evidence of a hyperresonant area in the abdomen. All ponies were observed for progression of clinical signs typical of ehrlichial colitis. Within 12 hours of initiation of treatment, only 1 treated pony had a rectal temperature > 38.8 C and most rectal temperatures were < 38.3 C. In contrast, only 2 control ponies had rectal temperatures < 38.8 C (mean rectal temperature values were significantly, P = 0.01, different between groups). In the treatment group, 4 ponies had no signs of depression after the first day of treatment, and only 1 had signs of depression after the second day of treatment (mean scores between groups were significantly different, P = 0.01). Feed intake remained normal in 4 treated ponies and improved in 4 of the remaining 5 after treatment began. Most of the control ponies had a progressive decrease in their feed intake during the observation period (mean scores between groups were significantly, P = 0.01, different). Three ponies in the control group and 2 ponies in the treatment group developed diarrhea before the treatment observation period began. Of the remaining 6 control ponies, 4 developed diarrhea after the treatment observation period began. None of the ponies in the treatment group developed diarrhea after treatment began. A profound decrease in borborygmal sounds, with silent periods lasting longer than 3 minutes, developed in 7 control ponies. Only 2 treatment ponies had borborygmi decreased to this level (mean scores between groups were significantly, P = 0.01, different). Three of 9 control group ponies developed severe disease and were euthanatized. All treatment-group ponies survived. In surviving ponies, clinical signs lasted 8 to 16 days (mean, 11.5) in the control group, but lasted only 1 to 7 days (mean, 4.5) in the treatment group (P = 0.01). Ponies from the treatment group did not develop clinical signs when reinoculated with Ehrlichia risticii at 4 and 8 months after original inoculation.

Fourteen ponies and 3 horses were inoculated with Ehrlichia risticii 2 to 20 months after a similar initial inoculation. Although all 17 had clinical signs of equine ehrlichial colitis after the first inoculation, 16 of 17 remained clinically normal following the second inoculation. The remaining pony had a transient fever and developed signs of depression. Before the initial inoculation, none of the animals had a detectable antibody titer to E risticii. All animals developed titers after the initial infection; however, a significant change of titer did not develop after reinoculation in most animals.

OBJECTIVE To evaluate use of serum amyloid A (SAA) and haptoglobin concentrations as prognostic indicators for horses with inflammatory disease in regard to euthanasia, complications, and hospitalization duration and cost. ANIMALS 20 clinically normal horses and 53 horses with inflammatory disease. PROCEDURES Total WBC count, neutrophil count, and fibrinogen, SAA, and haptoglobin concentrations were determined for clinically normal horses and horses with suspected inflammatory disease. Clinicopathologic values at admission were compared to test the use of SAA and haptoglobin concentrations in predicting euthanasia, complications, and hospitalization duration and cost. Haptoglobin and SAA concentrations of 22 horses were monitored during hospitalization to test the use of serial measurements in predicting survival and complications. RESULTS Neutrophil count and SAA and haptoglobin concentrations were significantly different at admission for horses with inflammatory disease, compared with those for clinically normal horses. Horses with colitis and peritonitis had significantly higher SAA and haptoglobin concentrations than clinically normal horses. A moderate positive correlation (r = 0.355) between hospitalization duration and haptoglobin concentration was identified. Horses with an increase in SAA concentration between 24 and 72 hours after admission, compared with admission SAA concentration, were significantly more likely (OR, 7.0; 95% confidence interval, 1.1 to 45.9) to be euthanized or develop complications. CONCLUSIONS AND CLINICAL RELEVANCE Concentrations of SAA and haptoglobin at admission were not significantly correlated with outcome in horses with inflammatory conditions. Acute-phase proteins likely have more utility in serial analysis rather than testing at a single time point for horses with inflammatory conditions.