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Background: Surgical manipulation of the intestine results in the massive movement of leukocytes into the intestinal muscularis at 24 hours. This is associated with muscle inhibition. The aim of this study was to temporally associate leukocyte extravasation with ileus after surgical manipulation., Methods: Rats underwent a simple manipulation of the small bowel and were killed at various times (0, 0.25, 0.5, 1, 3, 6, 12, and 24 hours) postoperatively. Jejunal circular-muscle contractile activity was assessed in a standard organ bath. Both extravasating and resident leukocytes were immunohistochemically stained in muscularis whole mounts., Results: Contractile activity was significantly reduced immediately after surgery, but rapidly returned to control levels at 3 hours. After recovery, muscle function decreased at 12 and 24 hours (41% and 81%, respectively). The resident muscularis macrophage network demonstrated cellular activation 1 hour postoperatively. The number of leukocytes increased over time (neutrophils, 67.5-fold; monocytes, 98.2-fold; and mast cells, 47-fold at 24 hours)., Conclusions: The functional results demonstrate a biphasic response in the suppression of muscle activity after surgical manipulation. Regression analysis (r2 = 0.998) of the temporal development of leukocyte infiltration and the protracted phase of muscle inhibition provides evidence for a correlation between cellular inflammation and postoperative dysmotility.

Background: The purpose of this study was to determine whether morphologic and functional changes in intestinal smooth muscle occur after small bowel transplantation (SBTx) and during chronic rejection., Methods: Orthotopic SBTx was performed in syngeneic (ACI-ACI, n = 6) and allogeneic (ACI-Lewis, n = 6) rat strain combinations. The latter received temporary immunosuppression (cyclosporine 15 mg/kg/body weight on postoperative days 0 to 6 once a day, postoperative days 7 to 28 every other day), which led to clinically quiescent chronic rejection of the graft by 90 days after SBTx. At that time structure and function of the jejunal muscularis externa were evaluated with histochemistry, mechanical organ bath, and intracellular electrical recording techniques., Results: Histochemistry showed a 1.5-fold thickening of the intestinal muscularis externa of syngeneic grafts, although contractile properties and intracellular electrical activity were not significantly different from controls. Allogeneic, chronically rejecting grafts showed a threefold increase in the thickness of the muscularis externa as a result of both smooth muscle hyperplasia and hypertrophy. Muscle strips from chronically rejecting grafts generated only 23% of the maximal contractile force generated by controls (bethanechol 300 mumol/L). Median effective concentration and threshold values were not significantly different. Intracellular electrical activity of circular smooth muscle cells revealed a significantly more depolarized resting membrane potential and a reduction in slow wave amplitude compared with controls., Conclusions: Syngeneic SBTx resulted in a significant thickening of the muscularis externa with an apparent adaptation to control in vitro physiologic function. Allogeneic SBTx subject to chronic rejection leads to profound morphologic changes and functional impairments. Changes in muscle structure and function evolve before the clinical signs of graft rejection.

Background: Our previous observation that nitric oxide (NO) is synthesized during antigen-specific immune reactions in vitro led us to investigate whether NO is produced during the in vivo immune response to a vascularized organ allograft., Methods: Orthotopic small-bowel transplantation in the rat was performed by standard microsurgical techniques in the LBNF1 to Lewis (rejection alone), Lewis to LBNF1 (graft-versus-host disease [GVHD] alone), and a syngeneic strain combination with and without immunosuppressive therapy with FK 506. The recipient serum NO2-/NO3- levels (stable end products of NO metabolism) were measured and erythrocytes were evaluated for the presence of nitrosylferrohemoglobin (specific for NO bound to hemoglobin)., Results: Animals that acutely rejected small-bowel allografts or suffered from acute GVHD showed significantly elevated serum NO2-/NO3- levels on days 6 and 9, and nitrosylferrohemoglobin electron paramagnetic resonance signals of different intensity were detected on days 3, 6, and 9. FK 506-treated allograft recipients and recipients of syngeneic grafts showed normal serum NO2-/NO3- levels and lacked nitrosylferrohemoglobin signals at all time points., Conclusions: This study indicates that NO is produced early during the course of small-bowel allograft rejection and GVHD and might therefore serve as a simple marker to detect such immune reactions.

Activated macrophages are known to oxidatively metabolize L-arginine to nitric oxide and citrulline. We have recently shown that nitric oxide is a potent inhibitory molecule in the in vitro rat mixed-splenocyte culture, resulting in inhibition of proliferation and cytolytic T-cell induction. We undertook this study using the sponge matrix allograft model in the rat to determine whether nitric oxide plays a role in an in vivo allograft response. Our experiments showed that on day 6 after grafting, when cytolytic activity of allograft-infiltrating cells is first detected, allogeneic graft fluid contains higher levels of NO2-/NO3- (the stable endproducts of nitric oxide metabolism) than syngeneic graft fluid. Furthermore, evaluation of the supernatants of cultured graft-infiltrating cells revealed that allogeneic graft-infiltrating cells spontaneously produce higher amounts of nitric oxide than syngeneic graft-infiltrating cells. The nitric oxide production was inhibited in the presence of NG-monomethyl-L-arginine (NMA), the competitive inhibitor of nitric oxide production. Most of the nitric oxide production was observed in the adherent macrophage fraction of the allograft-infiltrating cells. When allograft-infiltrating cells were cultured in the presence of NMA, donor-specific cytolytic activity was observed, whereas allograft-infiltrating cells cultured in the absence of NMA showed no cytolytic activity. These data show that nitric oxide production may play an important regulatory role in the allograft response.

S-shaped ileal reservoirs (SSRs) and double-barreled ileal reservoirs (DBRs) of equal size were placed 6 or 2 cm from the anus and evaluated over 1 year for their ability to improve the functional incontinence noted after an ileoanal anastomosis (IAA). Compared to straight IAA, both reservoirs prolonged intestinal transit (235 minutes versus 135 minutes, P less than 0.001) and alleviated frequency without causing nutritional abnormalities. The capacity of the reservoirs was greater than that of a comparable length of distal ileum in dogs (n = 6) with straight IAA (304 +/- 16 ml versus 102 +/- 2 ml, P less than 0.001). The SSRs (n = 9), in contrast to the DBRs (n = 10), developed excessive volume capacity (360 +/- 30 ml versus 254 +/- 104 ml, P less than 0.01) and obstructive complications. Reservoirs with 6 cm efferent conduits (n = 13), in contrast to those with a 2 cm efferent conduit (n = 6), underwent marked dilatation (334 +/- 24 ml versus 238 +/- 13 ml, P less than 0.005). Electromyography and manometry revealed the DBRs to be more contractile than the SSRs but less than ileum proximal to the anus in dogs with a straight IAA. Ileal reservoirs improve results after IAA. Reservoirs should be complaint and yet contractile (e.g., DBR) so as to discourage excessive dilatation, which is the harbinger of obstruction. Ileal conduits facilitate reservoir placement, but if longer than 2 cm they excessively impeded reservoir emptying, predisposing to excessive reservoir dilatation and obstruction. A DBR with a 2 cm efferent conduit results in continence without obstructive problems.

The effect of portal venous drainage (PV-D) on the survival of accessory small-bowel allografts was studied in a rat model. In the LBN-F1----LEW combination (rejection reaction only), grafts with caval venous drainage (CV-D) were rejected acutely (mean 11.8 days) and those with PV-D were rejected chronically (mean, 22.8 days). In the LEW----LBN-F1 combination, the survival of recipients subject perforce to a fatal graft-versus-host reaction was not influenced by the type of venous drainage used (CV-D: 14.1 days; PV-D: 14.8 days). These findings suggest that the delaying influence of the liver on the rejection process is not due to unspecific filtration of antigens but must involve their specific recognition or alteration. In the BN----LEW combination, in which rejection and the graft-versus-host reaction occur simultaneously, the type of venous drainage used did not influence graft survival (CV-D: 16.2 days; PV-D: 15.5 days), nor did it modify the rejection process. This indicates that the liver has a minor effect on the rejection process, sufficient to inhibit the rejection of semiallogeneic LBN-F1 grafts but insufficient to alter the rejection of allogeneic BN grafts by LEW recipients. With CV-D, LBN-F1 grafts were rejected as rapidly as were BN grafts. This unexpected finding may be explained by the fact that in the LBN-F1----LEW combination only rejection occurs, unimpeded by a graft-versus-host reaction, which is known to impair the immune system of the recipient; in the BN----LEW combination, however, the graft-versus-host reaction temporarily opposes the rejection reaction, thereby allowing prolonged graft survival.

Endorectal ileoanal anastomosis with proximal interposition of an ileal reservoir was evaluated experimentally in dogs as an approach to retain sphincteric control of defecation after proctocolectomy. Two months after the operative procedure, eight animals with a reservoir had four to eight semisolid stools per day and were continent. In contrast, six animals with straight ileoanal anastomosis were incontinent with 10 to 14 evacuations per day. Motility studies demonstrated a reduction of propulsive peristalsis within the undistended reservoir, which is considered the responsible factor for increased intestinal transit time and reduced stool frequency. Filling of the reservoir to capacity elicited strong peristaltic contractions, which may assure a more complete evacuation of the reservoir during defecation. Reservoir capacity increased substantially (150% to 200%) within 2 months but only to a minor degree thereafter, indicating that the reservoir does not dilate progressively into an atonic viscus. Motility patterns remained unaltered as the reservoir became more complaint with time. Mucosal alterations (flattening of villi, submucosal inflammation) were detected in the reservoir but did not result in nutritional defects within an observation period of 1 year.

The potential metabolic and technical consequences of systemic (portacaval anastomosis [PC-A]) as opposed to portal venous drainage (portaportal anastomosis [PP-A]) of orthotopic small bowel isografts was evaluated in a rat model. Rats with portacaval (PC) shunts were studied for comparison. During the study period of 6 months, rats with small bowel grafts (PP-A or PC-A) gained weight at rates equal to that of normal age-matched rats (+40% of the preoperative weight) whereas rats with PC shunts lost 20% of their weight. At autopsy 6 months after operation, rats with PC shunts had significant liver atrophy (2.0% of total body weight) in comparison with rats with orthotopic isografts. Moderate liver atrophy was detected in rats with grafts and PC-A in comparison with those with PP-A (2.6% versus 2.8% of total body weight, statistically not significant). Serum ammonia levels were significantly elevated for PC shunts (560 +/- 148 micrograms/dl) and PC-A (140 +/- 22 micrograms/dl) when compared with PP-A (83 +/- 10 micrograms/dl). In terms of technical difficulties, both PC-A and PP-A could be achieved with the same success rate. Systemic venous drainage for small bowel grafts is followed by metabolic alterations that are similar, although much less pronounced, to those seen after a PC shunt. Thus our findings do not offer compelling reasons to prefer PP-A over PC-A. However, with longer follow-up and the use of hepatotoxic immunosuppressive drugs, these minimal alterations may progress and induce metabolic sequelae of clinical significance. Under these circumstances it would be advisable to use the physiologic portal drainage rather than systemic venous drainage in small bowel transplantation.