Epithelial changes of congenital intestinal obstruction in a rat model.

INTRODUCTION: Intestinal atresia is a rare congenital affliction that is often associated with severe bacterial infections despite adequate neonatal surgery. Previous studies have focused on enteric nervous system variations. We hypothesized that epithelial systems (ES) may also be involved in the pathophysiology of postnatal disorders. MATERIALS AND METHODS: Global gene expression was measured by transcriptomic analysis in a rat model of induced intestinal atresia. The analyses then focused on genes involved in ES (enterocytes and goblet cells). Rat fetus small intestines at various stages of development (ED15, ED17, ED19, and ED21, n = 22), were used as non-operated controls and compared to the upper and lower segments of rat fetus small intestines with an induced atresia (n = 14; ligature at ED18). The pattern of gene expression was then confirmed by histochemistry, electron microscopy, and RT-qPCR. RESULTS: From ED15 to ED21, the expression of several genes exhibited a physiological increase of ES markers, with a significant increase at the end of gestation. The operated embryos exhibited significantly higher variations of gene expression in the proximal segment than in the distal segment in terms of absorption and the epithelial barrier. An increase in goblet cells and markers was observed in the proximal segment compared to the controls. CONCLUSION: Fetal intestinal obstruction accelerates maturation in the proximal segment and disrupts the intestinal wall in the distal segment, with a decrease in the number of mucosal cells. Moreover, the epithelial cells underwent significant changes, supporting the notion that intestinal disorders involve more than the ENS.

Quality of life outcomes in children born with duodenal atresia.

PURPOSE: The aim of this study was to determine long term quality of life (QoL) outcome for children who underwent surgery for duodenal atresia (DA). METHODS: Patients were identified from a prospective database of neonatal DA cases managed at a tertiary pediatric surgical centre. The QoL was measured using the validated PedsQL™ 4.0 core score and PedsQL™ gastrointestinal module; higher score equates to better QoL. Participants' scores were compared to published control cohorts, age-matching the core score. Trisomy 21 was identified a priori as a possible confounder, informing subgroup analyses for children with and without trisomy 21. RESULTS: Fifty-five families were invited to participate, with 38 surveys returned (39% male; median age 6.7y, range 2.7-17.3y). Seven participants had trisomy 21. There were no differences in QoL measures between all DA participants and controls. The PedsQL™ core score was significantly lower for DA participants with trisomy 21, but there was no accompanying difference in PedsQL™ gastrointestinal score. CONCLUSIONS: Children undergoing DA surgery in the neonatal period typically grow up to have a QoL comparable to a healthy population. Children with DA and trisomy 21 were more likely to have reduced overall QoL, albeit without an associated difference in gastrointestinal QoL score. LEVEL OF EVIDENCE: Prognosis study - level II (prospective cohort study).

Duodenal atresia with familial apple peel syndrome: case study with review of literature.

This is a case report of a neonate who was antenatally diagnosed with jejunal atresia which turned out to be duodenal atresia with apple peel syndrome. A previous sibling, who also had apple peel but with jejunal atresia, succumbed to sepsis after surgery. The first sibling had jejunal stenosis and had died of sepsis following surgery. Combination of duodenal atresia with apple peel is extremely rare. This coupled with a familial condition is rarer still. This case was challenging due to the short length of the gut and prolonged need for total parenteral nutrition and sepsis in postoperative period.

Clinicopathological study of intestinal smooth muscles, interstitial cells of Cajal, and enteric neurons in neonatal jejuno-ileal atresia with special reference to muscle morphometry.

PURPOSE: To assess the thickness of the intestinal smooth muscle layer and analyze the distribution and density of interstitial cells of Cajal (ICC) and enteric neurons in the proximal and distal segments of neonatal jejuno-ileal atresia. METHODS: This is an observational study done over a period of one year in which fifteen cases of jejuno-ileal atresia were included. All the cases underwent laparotomy and resection of the atretic segment with variable portions of the dilated proximal segment and distal segment. Histopathological analysis was done on the sections taken from proximal segments (at 3 cm, 5 cm & 8 cm) and the distal segment (at 2 cm) from the atretic portion. The mean thickness of the inner circular muscle layer (ICML) and outer longitudinal muscle layer (OLML) was assessed in the above segments using image morphometry. In addition, we also analyzed the distribution and density of the ICCs and enteric neurons in the different segments using immunohistochemistry for c-kit and S-100, respectively. Controls included normal jejuno-ileal segments resected from postmortem cases (n=7) and other nonrelated surgeries (n=3). The findings were then compared with each-other and with normal controls. RESULTS: Mean thickness of ICML and OLML of the proximal segments at 8 cm was significantly lower than at 3 cm and 5 cm of ileal and jejunal atresias (p≪ 0.5). The mean thickness of ICML and OLML of distal segments at 2 cm was similar to the controls in all the atretic cases (p≫ 0.5). The mean ICML thickness at proximal 8 cm segment was similar to the distal segment of both ileal & jejunal atresias (p= 0.06 & 0.37 respectively). The mean thickness of the OLML of the proximal 8 cm segments was significantly more than that at the distal segment (p=0.008) in ileal atresias but was similar in cases of jejunal atresias (p=0.07). Both the proximal and distal segments of ileal as well as jejunal atresias showed reduction in distribution and density of ICCs, as compared to normal controls. The density of ICCs in proximal segments at 3 cm and 5 cm was similar in both ileal (p=0.33) and jejunal segments (p=0.41) but was significantly lower than the proximal 8 cm segments (p≪0.05).The distribution of ICCs in the proximal segment at 8 cm was similar to the distal segments (p≪0.05). S-100 staining showed dense expression of neurons and glial cells with presence of submucosal giant ganglia within the proximal dilated segments as compared to the distal segments and the controls, which were more marked at 3 cm and 5 cm levels than at 8 cm level. CONCLUSION: Muscle morphometry using image analysis is a simple technique to assess the thickness of the intestinal smooth muscle layers. There is significant smooth muscle hypertrophy along with marked alteration in density and distribution of ICCs and ENS in the dilated proximal segments up to 5 cm, and relatively milder changes at 8 cm levels, as compared to the distal segments and the controls. TYPE OF STUDY: Prognosis study. LEVEL OF EVIDENCE: Level II.

Oesophageal atresia with tracheo-oesophageal fistula, ileal atresia and Hirschsprung's disease: outcome of a rare phenotype.

Oesophageal atresia with or without tracheo-oesophageal fistula, ileal atresia and Hirschsprung's disease are surgical malformations of the gastrointestinal tract typically diagnosed early in the neonatal period and varying in severity and prognosis. This report describes a full-term male newborn presenting simultaneous oesophageal atresia with distal tracheo-oesophageal fistula, ileal atresia and Hirschsprung's disease. In addition to the complex types of gastrointestinal malformations involved, the combination of ileal atresia and Hirschsprung's disease, as well as ganglion cells distal to intestinal atresia, resulted in a challenging diagnosis. Despite a successful outcome, the patient presented increased morbidity and prolonged hospitalisation. We highlight some important findings that may aid the early diagnosis of Hirschsprung's disease in this clinical setting. To our knowledge, the association of oesophageal atresia/tracheo-oesophageal fistula, ileal atresia and Hirschsprung's disease has not been previously reported.

Involvement of the enteroendocrine system in intestinal obstruction.

INTRODUCTION: Intestinal atresia, a rare congenital condition, is often associated with intestinal motility disorders despite adequate neonatal surgery. Previous studies have focused on changes in the enteric nervous system (ENS). We hypothesized that other components of the digestive tract could be involved in this condition. MATERIAL AND METHODS: In a rat model of surgically-induced intestinal obstruction, a transcriptome analysis was performed to measure the global gene expression. Then, analyzes were focused on genes expressed in ENS and neuroendocrine cells. Rat fetus small intestines at different developmental stages (ED15, ED17, ED19 and ED21, (n = 22)) were studied as controls and compared to the upper and lower segments of small intestines from rat fetuses with surgically-induced obstruction (n = 14; ligature at ED18). The gene expression pattern was confirmed by immunohistochemistry, electron microscopy and RT-qPCR. RESULTS: From ED15 to ED21, there was a physiological decrease in the gene expression of ENS markers and an increase in that of neuroendocrine genes. Regarding operated embryos, the changes in global gene expression were significantly higher in the proximal segment compared to the distal segment (18% vs. 9%). More precisely, a decrease in ENS gene expression and an increase in neuroendocrine gene expression were observed in the proximal segment compared to controls, indicating an accelerated maturation pattern. Immunohistochemistry and electron microscopy confirmed these findings. CONCLUSION: Fetal intestinal obstruction seems to induce an accelerated maturation in the proximal segment. Moreover, neuroendocrine cells undergo significant unexpected changes, suggesting that ENS changes could be associated with other changes to induce intestinal motility disorders.

Factors Conducive to Catch-Up Growth in Postoperative Jejunoileal Atresia Patients as Prognostic Markers of Outcome.

INTRODUCTION: Jejunoileal atresia (JIA) is a major congenital anomaly that requires surgical intervention in the neonatal period. During follow-up after surgery, there is usually a period of catch-up growth (CUG) that is sufficient for patients to regain normal weight for age. However, in some cases, CUG is inadequate. The aim of this study was to assess postoperative JIA patients to determine factors that may be associated with good CUG. MATERIAL AND METHODS: We retrospectively reviewed JIA patients treated at our institution by classifying them into three groups based on a comparison of postoperative weight with standard weight for healthy matched controls; that is, more than mean at 12 months after surgery (group M+), less than mean at 12 months after surgery but more than mean at 24 months after surgery because of CUG (group M-CUG+), less than mean at 24 months after surgery because there was no CUG (group M-CUG-). The following parameters were evaluated: gestational age, birth weight, sight of atresia: jejunum or ileum, length of residual small intestine, ratio of the length of residual small intestine to the predicted length of small intestine for matched gestational age (RP ratio), and duration of parenteral nutrition. RESULTS: A total of 42 patients were reviewed and classified into group M+ (n = 13), group M-CUG+ (n = 11), and group M-CUG- (n = 18). There were no significant differences in gestational age, birth weight, and duration of parenteral nutrition between the three groups. Incidence of JIA according to site was also similar. Length of residual small intestine was not significantly different between the three groups, but RP ratios were significantly higher in M+ (84.7 ± 15.4%) and M-CUG+ (83.8 ± 17.7%) compared with M-CUG- (69.2 ± 18.1%) (p = 0.02, respectively). CONCLUSIONS: A higher RP ratio (approximately 84%) would appear to be conducive to CUG while a lower ratio (less than 70%) was not. Actual length of residual small intestine was not relevant to CUG. We recommend calculating the RP ratio in postoperative JIA patients and using 70% as a cutoff value to predict patients with poor potential for CUG who may benefit from more aggressive nutritional support to achieve normal growth.

Medical management of motility disorders in patients with intestinal failure: a focus on necrotizing enterocolitis, gastroschisis, and intestinal atresia.

BACKGROUND: Intestinal failure (IF) is the dependence upon parenteral nutrition to maintain minimal energy requirements for growth and development. It may occur secondary to a loss of bowel length, disorders of motility, or both. Short bowel syndrome (SBS) is a malabsorptive state resulting from surgical resection, congenital defect, or diseases associated with loss of absorptive surface area. A particularly vexing problem is associated with whole bowel and/or segmental intestinal dysmotility. Motility disorders within the context of SBS and IF may relate to rapid intestinal transit secondary to loss of intestinal length, dysmotility associated with loss or poor antegrade peristalsis, or gastroparesis. Therapy may be classified into medical (prokinetic and antidiarrheal agents) and surgical to deal with the overdistended poorly motile bowel. METHODS: We performed a systematic review of the literature pertaining to IF, SBS, and dysmotility in the pediatric population with gastroschisis, necrotizing enterocolitis, and intestinal atresia. In addition to the available treatment options, we have provided a review of the literature and a summary of the available evidence. CONCLUSION: Despite relatively poor level of evidence regarding the application of promotility and antidiarrheal medications in patients with SBS and IF, these agents continue to be used. Herein, we provide a review of the physiology and pathophysiology of intestinal motility/dysmotility and available strategies for the use of promotility and antidiarrheal agents in patients with IF/SBS.

Antenatal diagnosis of bowel dilatation in gastroschisis is predictive of poor postnatal outcome.

PURPOSE: Although gastroschisis infants usually have a good outcome, there remains a cohort of babies who fare poorly. We inquired whether the presence of bowel dilatation in utero is predictive of postnatal course in infants with gastroschisis. METHODS: We compared the clinical course of infants who had bowel dilatation with those who did not. Bowel dilatation was defined as more than 20 mm in cross-sectional diameter on ultrasound at any gestational age. Outcome measures used were length of time of parenteral nutrition, death, and surgery for intestinal failure. RESULTS: A review of 170 infants with gastroschisis identified 74 who had dilatation of more than 20 mm (43.5%). There was no significant difference in the incidence of intestinal atresia in those with bowel dilatation and those without (P = .07). Those with bowel dilatation spent a longer period on parenteral nutrition. There were significantly more deaths in the group with bowel dilatation (P = .01). There was no significant difference in the number of infants requiring surgery for intestinal failure between the 2 groups (P = .47). CONCLUSIONS: We found that sonographically detected bowel dilatation more than 20 mm in utero in fetuses with gastroschisis may have value in predicting clinically significant adverse postnatal outcomes.

Comparative outcomes in intestinal atresia: a clinical outcome and pathophysiology analysis.

OBJECTIVE: To describe the outcomes of 130 intestinal atresias between 1982 and 2007. METHODS: Records were analyzed for location, demographics, prenatal diagnosis, birth weight, associated anomalies, surgery, establishment of oral intake, re-interventions and mortality. Statistical analyses were performed using Fisher test and ANOVA. RESULTS: There were 59 duodenal (30 male), 63 jejuno-ileal (34 male) and 8 colonic atresias (3 male). Prenatal diagnosis was established in 27 (46%) duodenal (DA), 26 (41%) jejuno-ileal (JIA) and 1 (12.5%) colonic atresias (CA). The mean birth weights, 2,380.5 g (SD 988) DA, 2,814 g (SD 755) JIA and 3,153 g (SD 527) CA were significantly different (p = 0.011). The mean gestational ages were 36, 37 and 37 weeks in DA, JIA and CA, respectively (p-NS). Associated congenital anomalies were seen in 41 (76%) DA, 32 (52%) JIA and 3 (38%) CA (p = 0.08, NS). The median time to full oral feeds after surgery was 18 days in DA, 20 days in JIA and 15.6 days in CA, respectively (p > 0.05). Eight patients with DA and nine patients with JIA underwent repeat surgery for adhesive obstruction. Adhesive bowel obstruction was most common in the first year after surgery in both groups (15/17). Gastroschisis was seen in six (10%) of JIA and three (35%) of CA. Two patients in the JIA group underwent bowel lengthening. Patients with gastroschisis and those with associated anomalies needed prolonged duration of TPN after JIA correction. There was no mortality in the duodenal atresia and colonic atresia groups. Six patients in the JIA group died, three of severe atresias coupled with multiple anomalies and three of cholestasis and sepsis. CONCLUSION: Distal atresias are difficult to diagnose antenatally. Proximal atresias have a significantly lower birth weight than distal atresias. Associated anomaly screening is important in all atresias.

An alternative management option for colonic atresia preventing loss of the ileocecal valve.

PURPOSE: Management of colonic atresia is contentious, with primary anastomosis having a notable risk of anastomotic leak. In addition, resection of the terminal ileum and ileocecal (i-c) valve is frequently performed, risking side effects such as diarrhea, vitamin B(12) deficiency, and gall stone formation. METHODS: The hospital coding system was searched for all patients with a diagnosis of colonic atresia between July 2005 and July 2008. Four term neonates were managed by formation of an ileostomy, a "blow hole" stoma just proximal to the atresia, and a mucus fistula distal to the atresia. RESULTS: Average time to full feeds was 7.5 days (range, 3-12 days), and average length of stay was 23 days (range, 13-47 days). Stoma management, problematic in 2 infants, was individualized by a specialist stoma nurse. Ileostomy output was refed into the mucus fistula. Complications included 3 episodes of prolapse of the blow hole stoma in infant 2. All of the infants returned to the operating theater at 1 to 3 months of age for restoration of bowel continuity and closure of the ileostomy. The atretic segment was resected, and an end-to-end anastomosis was performed. Recovery was straightforward in all cases. CONCLUSION: A procedure that retains the i-c valve and most of the colon through creation of a blow hole stoma in the distended proximal colon with a diverting ileostomy and mucus fistula is described. The technique is recommended in selected infants as bowel length and anatomy can be preserved, despite the use of multiple stomas.

Surgical experimental jejunoileal atresia in rat embryo.

PURPOSE: Jejunoileal atresia represents about 40% of intestinal atresia. After surgical repair, intestinal motility disorders are burdened with the postoperative outcome, and the origin of these troubles remains unclear. To specify the physiopathologic feature of jejunoileal atresia, we developed an experimental surgical model in fetal rat. METHODS: Time-dated pregnant rats were operated on at 18 days of gestational age. Hysterotomy was performed, followed by fetal wall incision. The exteriorization of the bowel loop was obtained by saline injection; the intestine was ligated and returned to the abdominal cavity before incisions were closed. Fetal intestine was excised at day 21, after cesarean delivery. RESULTS: Twenty-one pregnant rats underwent operation with 90% maternal survival rate. Among the 56 fetuses successfully operated on, 49 survived (87%). In fetuses with atresia, the mean birth weight (4.5 +/- 0.6 g) and the mean intestinal length (12.8 +/- 1.3 cm) were significantly lower compared to sham fetuses and controls. CONCLUSION: The rat model offers the advantage of a low-expense mammal model with a wide panel of probes and reagents available for the study of the gut. This model of jejunoileal atresia could be used to study the consequences of prenatal intestinal obstruction on fetal gut.

Pyloric obstruction, duodenal dilatation, and extrahepatic cholestasis: a neonatal triad suggesting multiple intestinal atresias.

Whereas physiologic jaundice constitutes a common finding in neonates, a few cases present with cholestatic jaundice owing to various pathologic conditions, including extrahepatic biliary obstruction. We report the case of a 2-day-old female neonate presenting with neonatal cholestasis, nonbilious vomiting with pyloric obstruction, and multiple intestinal atresias. A pathognomonic clinicoradiologic triad is described, based on clinical data, plain abdominal x-ray, and ultrasound examination.

The fibroblast growth factor pathway serves a regulatory role in proliferation and apoptosis in the pathogenesis of intestinal atresia.

BACKGROUND/PURPOSE: Intestinal atresia occurs in 1:5000 live births and is a neonatal challenge. Fibroblast growth factor receptor 2b (Fgfr2b) is a critical developmental regulator of proliferation and apoptosis in multiple organ systems including the gastrointestinal tract (GIT). Fgfr2b invalidation results in an autosomal recessive intestinal atresia phenotype. This study evaluates the role of Fgfr2b signaling in regulating proliferation and apoptosis in the pathogenesis of intestinal atresia. METHODS: Wild-type and Fgfr2b-/- embryos were harvested from timed pregnant mice. The GIT was harvested using standard techniques. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling) was used to evaluate apoptosis and bromodeoxyuridine to assess proliferation by standard protocols. Photomicrographs were compared (Institutional Animal Care and Use Committee-approved protocol 32-02). RESULTS: Wild-type and mutant GIT demonstrate that deletion of the Fgfr2b gene results in inhibition of epithelial proliferation and increased apoptosis. Inhibited proliferation and increased apoptosis are specific to those tissues of normal Fgfr2b expression, corresponding to the site of intestinal atresia. CONCLUSIONS: The absence of embryonic GIT Fgfr2b expression results in decreased proliferation and increased apoptosis resulting in GIT atresia. The regulation of proliferation and apoptosis in intestinal cells as a genetically based cause of intestinal atresia represents a novel consideration in the pathogenesis of intestinal atresia.

The basic biology of apoptosis and its implications for pediatric surgery.

Apoptosis, or programmed cell death, is an evolutionarily conserved and highly regulated process of nonfunctional cell death. Through this process, the body disposes of unwanted cells by self-destruction: it is our final defense against damaged cells. In the last decades, many of the essential pathways that control this phenomenon have been elucidated. Apoptosis plays an important role in developmental processes, as well as in cellular homeostasis. This process is known to be accelerated or diminished in many pathologic states. Therefore the understanding of apoptotic regulation has significant clinical ramifications. This article reviews the basic understanding of programmed cell death with respect to areas of interest to pediatric surgeons, including: Hirschsprung disease, intestinal atresias, testicular disorders, short bowel syndrome, ischemia-reperfusion injury and pediatric oncology. Pro or antiapoptotic interventions may become a future target for cell and organ protection in patients suffering from these diseases.

Biliary atresia associated with jejunal atresia and a review of the literature in Japan.

An unusual case of biliary atresia with jejunal atresia is herein described. Only 12 cases demonstrating biliary atresia associated with a jejunal atresia have been previously reported in Japan. The pathogenesis of biliary atresia is thought to be secondary to the influence of jejunal atresia.

A case report of midgut atresia and spontaneous closure of gastroschisis.

We report a case in which a neonate with a prenatal diagnosis of gastroschisis was born with midgut atresia and the mummified remains of the midgut arising from a spontaneously closed abdominal wall defect. As our ability to prenatally diagnose abdominal wall defects has improved, we have gained some insight into the prenatal natural history of this pathological process. We present a case in which an abdominal wall defect spontaneously closed and was associated with an apparent in utero midgut vascular accident. This unusual case provides some insight into the mechanisms underlying the pathophysiology of gastroschisis.

J. H. Louw Memorial Lecture. Outreach, origins and a hedgehog.

Professor J. H. Louw is honoured in this lecture for the major contribution he made to the development of paediatric surgery in South Africa as a specialty in its own right. Although he is perhaps best known internationally for his contribution to our understanding of the aetiology of small-bowel atresias, it may be that his greatest legacy lies in those he taught, many of whom are in the audience. He was a man who demanded the highest standards, both of himself and of his colleagues, and despite many other leadership roles and responsibilities in surgery generally, always considered that his first responsibility was to paediatric surgery. It may be fitting, therefore, that this lecture deals with two aspects that were dear to Professor Louw, namely the provision of specialist care for children with surgical conditions, and recent research into the causes of congenital structural abnormalities.

The occurrence of unusual smooth muscle bundles expressing alpha-smooth muscle actin in human intestinal atresia.

BACKGROUND/PURPOSE: Intestinal dysmotility is an important problem in the postoperative management of patients with intestinal atresia (IA). Changes in the intramural components have so far been histochemically and immunohistochemically examined in both the proximal and distal segments of IA, but no detailed analysis of the muscular elements has been performed. The aim of this study was to carefully examine any alterations in the muscular elements in the intestines from patients with IA. METHODS: Resected intestines were obtained from 6 patients with ileal atresia, 4 patients with jejunal atresia, and 3 controls without gastrointestinal diseases obtained by autopsy (congenital diaphragmatic hernia). All specimens were immunochemically stained with a monoclonal antibody to alpha-smooth muscle actin (alpha-SMA) as a smooth muscle marker. RESULTS: In the normal small intestine, almost all the enteric smooth musculature were positive for alpha-SMA antiserum, except for the bulk of the circular musculature. In the proximal segments of all cases with IA, a reduced staining intensity for alpha-SMA was observed mainly in the severely hypertrophic muscle layers. In addition, some bundles of smooth muscle also were located in the submucosal connective tissue near the border of the innermost layer of the circular musculature, in which large amounts of smooth muscle fibers extended occasionally from the innermost layer of the circular musculature to the muscularis mucosae in the proximal segments of 4 cases. In the distal segments of IA, the distribution of alpha-SMA-positive smooth muscle fibers was similar to that in the control intestines, excluding mild to moderate hypertrophy of the muscular layers. CONCLUSIONS: Both severe hypertrophy and a reduced immunoreactivity for alpha-SMA were observed in the circular muscle layer of the proximal segments. In addition, the occurrence of alpha-SMA-positive abnormal smooth muscle fibers was recognized in the submucosal layers of the proximal segments, thus, suggesting a delay in the intestinal muscular formation or a regressive reaction secondary to dilatation. These muscular alterations in the proximal segments might be considered to contribute to the postoperative intestinal dysmotility in IA cases.

Alterations of the intramural nervous distributions in a chick intestinal atresia model.

The postoperative intestinal dysmotility seen in intestinal atresia (IA) is usually found in association with a dilatation of the proximal intestinal segment, but the etiology of this disorder is not yet fully understood. A chick IA model was made by cutting the postumbilical midgut on d 11 in ovo. The operated chicks were euthanized 2 d after hatching. The samples were divided into two groups according to the extent of the dilatation of proximal ileal segments. Cryostat sections were processed for immunohistochemistry by the use of antisera to protein gene product 9.5, vasoactive intestinal polypeptide, substance-P, and alpha-smooth muscle actin and were also stained by NADPH-diaphorase. Tn highly dilated proximal segments, a decreased number of protein gene product 9.5-positive fibers was found in both the circular muscle and submucous layers. The number of nerve fibers positive for vasoactive intestinal polypeptide, substance-P, and NADPH-diaphorase also decreased in the circular muscle layer, particularly in the deep muscular plexus. Hypertrophy and an alteration of the staining intensities in the circular muscle layer were also revealed by a-smooth muscle actin staining. The nerve distribution of the distal segments was indistinguishable from that of the age-matched controls and the sham-operated group. Abnormalities in the intramural nerves are only found in the proximal ileal segment of the IA models. The abnormal nerve distribution of the proximal segment might thus be implicated in the postoperative dysmotility of the intestine in IA.