resuscitation

GASTROENTEROLOGY Vol. 114, No. 4

A434 AGA ABSTRACTS

• G1767 ARE COLLAGENOUS AND LYMPHOCYTIC COLITIS ONE DISEASE? A HISTOLOGIC ANALYSIS OF 178 CASES. K Wouters*, F. Baert, C. Sempoux, W. Tanghe, M. Marichal, C. Cuveiier, P. Rntgeerts, N. Ectors*, K. Geboes* and the Belgian IBD group. *Department of Pathology, K.U. Leuven, Belgium. Background: The diagnosis of microscopic colitis (MC) depends largely upon histologic analysis of multiple colonic biopsies. Two major subtypes have been identified: Collagenous colitis (CC) and Lymphocytic colitis (LC). Whether these are two distinct entities is still not clear. Furthermore, some patients present with clinical features suggestive of MC but have not characteristic microscopic features. Aim: The purpose of the present study was to identify patients showing features of both LC and CC, and to verify the classical diagnostic criteria. Material and Methods: Colonic biopsies taken at the moment of diagnosis (at least 4) of 178 patients from 14 different centres identified as having MC were reviewed. A diagnosis of CC was accepted when the subepitheiial collagen table measured 10 micron or more. A diagnosis of LC was accepted when 25 or more intraepithelial lymphocytes (IEL) were counted for 100 surface epithelial cells. In addition features of active and chronic inflammation had to be present. Results: 88 patients were identified as having CC (mean age 64.1 yrs, range 23-87; M/F=24/64; mean thickness of collagen band=ll.5+/-3 micron). 70 patients had LC (mean age 63 yrs, range 22-91; M/F=34/36; mean IEL=29.8+/-9). In 1 case an erosion was present. 20 patients did not fuUfill the diagnostic criteria of either LC or CC (mean age 65yrs, range 19-82; IEL were increased in 12 pts; mean=8.5, range 5-15; a thickened collagen band was present in 10; mean=5.3 micron). In 2 cases a striking high number of macrophages-histiocytes (1) or giant cells (1) were present in a subepithelial position. 25/88 (28%) patients of the CC group had an increase of IEL with a mean of 13.6 (range 5-27). 15/70 (21%) patients with LC had a thickened collagen table (mean 5.2+/-2.1, range 3-8). Conclusion: Only a limited number of patients (25%) show features of both CC and LC. Yet if a thickening of the subepithelial collagen table and increase of IEL are present, the features are less prominent than in biopsies from patients with typical features. Long term follow up is indicated to see if these patients develop full blown characteristics of one disease, or if they form a particular subset. A subset of patients have only mild alterations with a clinical pattern suggestive of MC. Histiocytic colitis may be a new form of MC. • G1768 XANTHINE OXIDASE, REACTIVE OXIDANTS AND NEUTROPHILS IN HEPATIC INJURY FOLLOWING HEMORRHAGIC SHOCK/ RESUSCITATION. Y. Yamakawa. M. Takano, KB. Wilkins, N. Tien, M. Patel and GB. Bulkley. Johns Hopkins Medical Institutions, Baltimore, MD. We have reported that inhibition of xanthine oxidase (XO), with either allopurinol or a tungsten diet, inhibited both neutrophil accumulation and centrilobular necrosis in the liver following hemorrhagic shock/resuscitation (S/R). (Shock, 5: 1-9, 1996) However, this association between XO activity, neutrophil accumulation, and hepatic injury doesn't necessarily indicate causality. We therefore reevaluated this relationship following selective ablation of its components. Un-heparinized male rats were bled to a mean blood pressure of 45 ~_3 mmHg. After 2h. of shock, the rats were resuscitated by reinfusion of shed blood and crystalloid. SIR alone generated centrilobular neutrophil accumulation at 6h, followed by predominantly centrilobular hepatocellular injury, evaluated by alcohol dehydrogenase (ADH) and asparate aminotransferase (AST), and centrilobular necrosis by trypan blue exclusion and (blinded) histologic exam. Each of these components was attenuated by either XO inhibition with allopurinol, antioxidant treatment with N-acetylcysteine (NAC), or severe neutropenia ( < 103/ml)induced by vinblastine.

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In each case, the degree of neutrophil accumulation at 6h was proportional to the hepatocellular injury seen at 24h. However, XO inhibition with allopurinol failed to further attenuate either neutrophil accumulation nor hepatcellular injury in the neutropenic rats. These findings suggest that reactive oxidants generated by XO at reperfusion mediate hepatcellular injury by triggering neutrophil accumulation in the centrilobular sinusoids.

G1769

THE LATE PHASE REACTION IN RAT INTESTINE: PERSISTENT PATHOPHYSIOLOGY A F I ~ R A SINGLE ORAL DOSE OF ANTIGEN. P-C Yang, MC Berin, MA Benjamin and MH Perdue. Intestinal Disease Research Program, McMaster University, Hamilton, ON, Canada Reactions to antigen result in pathophysiology and inflammation in the airways that continues for days after initial challenge (termed the late phase reaction, LPR). Little information exists on LPR in the intestinal tract. Here, we characterized the physiological, cellular and pathological changes in rat jejunum during LPR. METHODS: Sprague-Dawley (SD) and mast-ceU deficient (Ws/Ws) rats were sensitized to a model protein, horseradish peroxidase (HRP). Rats were challenged 14 days later with ig HRP. Naive unchallenged and challenged rats served as controls. At 0.5, 8, 48 and 72 h later, jejunal segments were excised and mounted in Ussing chambers where short-circuit current (Isc) and conductance were measured. Immune ceils were counted by light microscopy and ultrastrncture was assessed by electron microscopy (EM). RESULTS: SD rats. Baseline Isc (indicating ongoing ion secretion) increased 40% to 65% and conductance (indicating increased permeability) increased 34% to 52% at all time points in intestine from sensitized rats following HRP challenge, indicating persistent pathophysiology. Numbers of mast cells (MC), eosinophils (Eo), neutrophils (N) and mononuclear ceils (MNC) were significantly greater in mucosa of sensitized rats vs controls and showed additional increases after HRP challenge. By EM, degranulation of MC and Eo was frequently observed. Abnormalities were identified in intestinal epithelial cells, including large vacuoles and edematous mitochondria. In addition, disruption of the basement membrane was observed. Ws/Ws rats. After sensitization, serum IgE was increased to the same extent as in SD rats, but no MC were present in intestinal mucosa. Ussing chamber studies and microscopy revealed completely normal physiology and morphology. Eo, N and MNC numbers were not statistically different from naive controls. CONCLUSIONS: In rat small intestine, LPR after ig antigen challenge is characterized by infiltration of inflammatory ceils, associated with significant structural and functional abnormalities, all dependent on the presence of MC. We concluded that MC play a key role in LPR of gut mucosa, and are directly or indirectly responsible for gut dysfunction, that continues for days after antigen exposure. This research was funded by a grant from The Medical Research Council of Canada. • G1770 ACTIVATION OF TRANSCRIPTIONAL FACTOR AP-1 AND NF-•B OCCURS IN CELLS SURVIVING INTESTINAL ISCHEMIAREPERFUSION IN RATS, Ky, yCh, M. Yeh, DN. Granger, and J. Glass. The Cancer Center, Departments of Medicine, and Molecular and Cellular Physiology, LSU Medical Center, Shreveport, LA. The intestinal epithelium is a constantly renewing tissue. Cell proliferation takes place at defined positions in the crypt. Cell differentiation occurs as cells migrate to new positions. Cell death occurs at the crypt bottom and villus tip. Although cell proliferation, differentiation and death proceed in different locations, these events are regulated by poorly defined feedback mechanisms. To examine the molecular events related to cellular homeostasis, we surgically induced intestinal ischemia-reperfusion (IR) and examined morphological damage and repair in parallel to changes in the activity of nuclear activator protein 1 (AP-1) and nuclear factor kappa B (NF-~:B). Both AP-1 and NF-KB are cellular sensors to oxidative stress and mitogens and are early transcription factors that are activated after partial hepatectomy. Activation of AP-1 and NF-~:B may occur after damage induced by IR. Adult rats were fed 5% glucose in saline overnight. After laparotomy to expose the small intestine, the blood supply of a 10 cm jejunal loop was clamped for 30 min to produce an episode of IR. Rats were killed at defined times after reperfusion. The ischemia-reperfused jejunum (RJ) and the immediate proximal control jejunum (CJ) were collected for analyses. At 3 and 6 h after reperfusion, a 60% reduction in the villus height was observed. The villus height did not increase until 24 h and recovered to the normal height at 48 h after reperfusion. In contrast, crypt depth did not change throughout the experimental period, although an insignificant increase was noticed at 12 h after IR. Northern analysis showed that the mucosal sucrase-isomaltase mRNA decreased about 60-70% and cryptdin I mRNA increased 3-5 fold at 3 and 6 h, suggesting that the loss of mature villus cells attributed to shortened villus height. Electrophoretic mobility shift assays of nuclear extracts showed that in the ILl, AP-1 activity increased~5 fold at 1 h and then subsided thereafter to the resting level by 12 h. In the CJ, a 2-fold increase occurred during 1 to 6 h period and returned to the normal low level by 12 h. Addition of anti-c-fos or anti-c-jun antiserum greatly increased activity, but only anti-cfos produced a supershift band. The c-fos mRNA also showed 3 to 5-fold increase at 1 h and subsided thereafter. IR induced a greater change in NF-~zB than AP-1 activity, as NF-~:B increased 5- and 7-fold at 1 and 3 h respectively and remained 3-fold higher than the resting level at 12 h. In the CJ, NF-~:B was not activated between 1 and 6 h but increased 2-fold at 12 h. Anti-p50, but not p65 antiserum produced a supershift band with the disappearance of the activated complex, suggesting that the p50/p50 homodimers and/or p50 heterodimers with other members of NF-~:B family are activated. In