The pathology of infantile hypertrophic pyloric stenosis after healing

Antral Variation of Murine Gastric Pacemaker Cells Informed by Confocal Imaging and Machine Learning Methods

The Interstitial Cells of Cajal (ICC) are specialized gastrointestinal (GI) pacemaker cells that generate and actively propagate electrophysiological events called slow waves. Slow waves regulate the GI motility necessary for digestion. Several functional GI motility disorders have been associated with depletion in the ICC. In this study, a validated Fast Random Forest (FRF) classification method using Trainable WEKA Segmentation for segmenting the networks of ICC was applied to confocal microscopy images of a whole mount tissue from the distal antrum of a mouse stomach (583 × 3,376 × 133 μm³, parcellated into 24 equal image stacks). The FRF model performance was compared to 6 manually segmented subflelds and produced an area under the receiver-operating characteristic (AUROC) of 0.95. Structural variations of ICC network in the longitudinal muscle (ICC-LM) and myenteric plexus (ICC-MP) were quantified. The average volume of ICC-MP was significantly higher than ICC-LM at any point throughout the antral tissue sampled. There was a pronounced decline of up to 80% in ICC-LM (from 3,705 μm³ to 716 μm³) over a distance of 279.3 μm, that eventually diminished towards the distal antrum. However, an inverse relationship was observed in ICC-MP with an overall increase of up to 157% (from 59,100 μm³ to 151,830 μm³) over a distance of approximately 2 mm that proceeds towards the distal antrum.

Slow-wave coupling across a gastroduodenal anastomosis as a mechanism for postsurgical gastric dysfunction: evidence for a "gastrointestinal aberrant pathway"

Postsurgical gastric dysfunction is common, but the mechanisms are varied and poorly understood. The pylorus normally acts as an electrical barrier isolating gastric and intestinal slow waves. In this report, we present an aberrant electrical conduction pathway arising between the stomach and small intestine, following pyloric excision and surgical anastomosis, as a novel disease mechanism. A patient was referred with postsurgical gastroparesis following antrectomy, gastroduodenostomy, and vagotomy for peptic ulceration. Scintigraphy confirmed markedly abnormal 4-h gastric retention. Symptoms included nausea, vomiting, postprandial distress, and reflux. Intraoperative, high-resolution electrical mapping was performed across the anastomosis immediately before revision gastrectomy, and the resected anastomosis underwent immunohistochemistry for interstitial cells of Cajal. Mapping revealed continuous, stable abnormal retrograde slow-wave propagation through the anastomosis, with slow conduction occurring at the scar (4.0 ± 0.1 cycles/min; 2.5 ± 0.6 mm/s; 0.26 ± 0.15 mV). Stable abnormal retrograde propagation continued into the gastric corpus with tachygastria (3.9 ± 0.2 cycles/min; 1.6 ± 0.5 mm/s; 0.19 ± 0.12 mV). Histology confirmed ingrowth of atypical ICC through the scar, defining an aberrant pathway enabling transanastomotic electrical conduction. In conclusion, a "gastrointestinal aberrant pathway" is presented as a novel proposed cause of postsurgical gastric dysfunction. The importance of aberrant anastomotic conduction in acute and long-term surgical recovery warrants further investigation.NEW & NOTEWORTHY High-resolution gastric electrical mapping was performed during revisional surgery in a patient with severe gastric dysfunction following antrectomy and gastroduodenostomy. The results revealed continuous propagation of slow waves from the duodenum to the stomach, through the old anastomotic scar, and resulting in retrograde-propagating tachygastria. Histology showed atypical interstitial cells of Cajal growth through the anastomotic scar. Based on these results, we propose a "gastrointestinal aberrant pathway" as a mechanism for postsurgical gastric dysfunction.

Maternal and pregnancy characteristics and risk of infantile hypertrophic pyloric stenosis

BACKGROUND/PURPOSE

The incidence of infantile hypertrophic pyloric stenosis (IHPS) in Sweden decreased dramatically during the 1990s. The aim of the study was to examine IHPS risk factors and the possible change in them as the incidence declined.

METHODS

This is a case-control study including 3608 surgically treated IHPS cases and 17588 matched controls during 1973-2008. Cases were identified in the Swedish National Patient Register and data on possible risk factors were collected from the Swedish Medical Birth Register. The association between study variables and IHPS was analyzed using conditional logistic regression for the whole study period and separately for periods with high and low IHPS incidences.

RESULTS

Prematurity (OR, 2.54; 95% CI, 2.06-3.14), caesarean delivery (OR, 1.67; 95% CI, 1.51-1.86), maternal smoking (OR, 1.82; 95% CI, 1.53-2.16), and young maternal age (< 20yrs) (OR, 1.42; 95% CI, 1.17-1.73) were associated with an increased IHPS risk. Birth order 2 (OR, 0.78; 95% CI, 0.71-0.85) or more was associated with a lower IHPS risk. ORs for smoking increased at low incidence rate.

CONCLUSION

We report caesarean section, prematurity, primiparity, young maternal age, and smoking as significant IHPS risk factors. The impact of smoking was higher during periods with a low incidence.

Neural stem cell therapies for enteric nervous system disorders

The enteric nervous system is vulnerable to a range of congenital and acquired disorders that disrupt the function of its neurons or lead to their loss. The resulting enteric neuropathies are some of the most challenging clinical conditions to manage. Neural stem cells offer the prospect of a cure given their potential ability to replenish missing or dysfunctional neurons. This article discusses diseases that might be targets for stem cell therapies and the barriers that could limit treatment application. We explore various sources of stem cells and the proof of concept for their use. The critical steps that remain to be addressed before these therapies can be used in patients are also discussed. Key milestones include the harvesting of neural stem cells from the human gut and the latest in vivo transplantation studies in animals. The tremendous progress in the field has brought experimental studies exploring the potential of stem cell therapies for the management of enteric neuropathies to the cusp of clinical application.

Relationship between enteric neurons and interstitial cells in the primate gastrointestinal tract

BACKGROUND

Morphological studies have revealed a close anatomical relationship between enteric nerve terminals and intramuscular ICC (ICC-IM) which supports a role for ICC-IM as intermediaries in enteric motor neurotransmission. Recently, a second type of interstitial cell previously described as 'fibroblast-like' but can now be identified by platelet-derived growth factor receptor-α expression, has also been implicated in enteric neurotransmission in rodents. The present study was performed to determine if enteric nerve fibers form close anatomical relationships with ICC and PDGFRα(+) cells throughout the primate GI tract.

METHODS

Immunohistochemical experiments and confocal microscopy were performed to examine the relationship between excitatory and inhibitory motor neurons, ICC and PDGFRα(+) cells throughout the monkey GI tract.

KEY RESULTS

The pan neuronal marker. Protein gene product 9.5 (PGP9.5) was used to label all enteric neurons and substance-P (sub-P) and neuronal nitric oxide synthase (nNOS) to label excitatory and inhibitory neurons, respectively. Double labeling with Kit revealed that both classes of nerve fibers were closely apposed with ICC-IM in the stomach, small intestine and colon (taenia and inter-taenia regions), but not with ICC at the level of the myenteric plexus (ICC-MY). Varicose enteric nerve fibers were closely associated with ICC-IM for distances up to 250 μm. Both excitatory and inhibitory nerve fibers were also closely apposed to PDGFRα(+) cells throughout the primate GI tract.

CONCLUSIONS & INFERENCES

The close anatomical relationship between enteric nerve fibers and ICC-IM and PDGFRα(+) cells throughout the GI tract of the Cynomolgus monkey provides morphological evidence that these two classes of interstitial cells may provide a similar physiological function in primates as has been attributed in rodent animal models.

Interstitial cells in the primate gastrointestinal tract

Kit immunohistochemistry and confocal reconstructions have provided detailed 3-dimensional images of ICC networks throughout the gastrointestinal (GI) tract. Morphological criteria have been used to establish that different classes of ICC exist within the GI tract and physiological studies have shown that these classes have distinct physiological roles in GI motility. Structural studies have focused predominately on rodent models and less information is available on whether similar classes of ICC exist within the GI tracts of humans or non-human primates. Using Kit immunohistochemistry and confocal imaging, we examined the 3-dimensional structure of ICC throughout the GI tract of cynomolgus monkeys. Whole or flat mounts and cryostat sections were used to examine ICC networks in the lower esophageal sphincter (LES), stomach, small intestine and colon. Anti-histamine antibodies were used to distinguish ICC from mast cells in the lamina propria. Kit labeling identified complex networks of ICC populations throughout the non-human primate GI tract that have structural characteristics similar to that described for ICC populations in rodent models. ICC-MY formed anastomosing networks in the myenteric plexus region. ICC-IM were interposed between smooth muscle cells in the stomach and colon and were concentrated within the deep muscular plexus (ICC-DMP) of the intestine. ICC-SEP were found in septal regions of the antrum that separated circular muscle bundles. Spindle-shaped histamine(+) mast cells were found in the lamina propria throughout the GI tract. Since similar sub-populations of ICC exist within the GI tract of primates and rodents and the use of rodents to study the functional roles of different classes of ICC is warranted.

Progress in research of interstitial cells of Cajal

Interstitial cells of Cajal (ICCs) are a kind of cells mainly found in the gastrointestinal tract as pacemaker and signal transduction cells. They have a close connection with muscular cells and terminal neurons and can stimulate and promote gastrointestinal motility. With the help of electron microscopes, we can clearly recognize their distribution and inner structure. C-kit protein is expressed by ICCs. Besides, many disorders of gastrointestinal motility are related to ICCs. In recent years, many scholars have found the trace of ICCs in different organs such as the gastrointestinal tract, biliary tract, bladder, and uterus, and they have tried to state the relationship between abnormal ICCs and some diseases. This article will review the progress in research of ICCs in terms of their origin, morphology, receptors, function, and related diseases.

The involvement of nitric oxide synthase neurons in enteric neuropathies

Nitric oxide (NO), produced by the neural nitric oxide synthase enzyme (nNOS) is a transmitter of inhibitory neurons supplying the muscle of the gastrointestinal tract. Transmission from these neurons is necessary for sphincter relaxation that allows the passage of gut contents, and also for relaxation of muscle during propulsive activity in the colon. There are deficiencies of transmission from NOS neurons to the lower esophageal sphincter in esophageal achalasia, to the pyloric sphincter in hypertrophic pyloric stenosis and to the internal anal sphincter in colonic achalasia. Deficits in NOS neurons are observed in two disorders in which colonic propulsion fails, Hirschsprung's disease and Chagas' disease. In addition, damage to NOS neurons occurs when there is stress to cells, in diabetes, resulting in gastroparesis, and following ischemia and reperfusion. A number of factors may contribute to the propensity of NOS neurons to be involved in enteric neuropathies. One of these is the failure of the neurons to maintain Ca(2+) homeostasis. In neurons in general, stress can increase cytoplasmic Ca(2+), causing a Ca(2+) toxicity. NOS neurons face the additional problem that NOS is activated by Ca(2+). This is hypothesized to produce an excess of NO, whose free radical properties can cause cell damage, which is exacerbated by peroxynitrite formed when NO reacts with oxygen free radicals.

Reduction of interstitial cells of Cajal in esophageal atresia

OBJECTIVES

Postrepair esophageal dysmotility and gastroesophageal reflux are well-known consequences in patients with congenital esophageal atresia (EA) with or without distal tracheoesophageal fistula (TEF). The interstitial cells of Cajal (ICC), considered the intestinal pacemaker, are altered in congenital diseases with abnormal peristalsis, but no data are available for EA. Therefore, presence and maturation of ICC was verified in EA-TEF newborns.

PATIENTS AND METHODS

Fifteen full-term neonates underwent repair of EA-TEF. Control specimens were from 10 newborns who died of nonesophageal diseases. Specimens from upper pouch, fistula, proximal, and distal esophagus were processed for hematoxylin and eosin, c-kit immunohistochemistry for ICC identification, and transmission electron microscopy. Frequency of c-kit-positive cells was evaluated in 20 fields per slide using a visual score (absent, very low, low, medium, high, very high). Morphocytometry and statistical analysis were also performed.

RESULTS

In the proximal normal esophagus, ICC frequency was very high (3 cases), high (5), and medium (2); distally, it was high (4) and medium (6). In EA-TEF upper pouch, it was high (2) and medium (13); in the fistula, it was medium (5), low (6), very low (3), and absent (1). Morphocytometry confirmed these results. Comparison between pouch and fistula versus proximal and lower esophagus, respectively, showed statistically significant differences. Transmission electron microscopy demonstrated ICC immaturity in EA-TEF.

CONCLUSIONS

The significant lower ICC density in EA-TEF is in favor for the pathogenesis of esophageal dysmotility frequently observed in such patients.

Igf1r+/CD34+ immature ICC are putative adult progenitor cells, identified ultrastructurally as fibroblast-like ICC in Ws/Ws rat colon

The colon of Ws/Ws mutant rats shows impairment of pacemaker activity and altered inhibitory neurotransmission. The present study set out to find structural correlates to these findings to resolve mechanisms. In the colon of Ws/Ws rats, interstitial cells of Cajal associated with Auerbach's plexus (ICC-AP) were significantly decreased and ICC located at the submuscular plexus and intramuscular ICC were rarely observed based on immunohistochemistry and electron microscopy. Ultrastructural investigations revealed that there was no overall loss of all types of interstitial cells combined. Where loss of ICC was observed, a marked increase in fibroblast-like ICC (FL-ICC) was found at the level of AP. Immunoelectron microscopy proved FL-ICC to be c-Kit(-) but gap junction coupled to each other and to c-Kit(+) ICC; they were associated with enteric nerves and occupied space normally occupied by ICC in the wild-type rat colon, suggesting them to be immature ICC. In addition, a marked increase in immunoreactivity for insulin-like growth factor 1 receptor (Igf1r) occurred, co-localized with CD34 but not with c-Kit. A significantly higher number of Igf1r(+)/CD34(+) cells were found in Ws/Ws compared to wild-type rat colons. These CD34(+)/Igf1r(+) cells in the Ws/Ws colon occupied the same space as FL-ICC. Hence we propose that a subset of immature ICC (FL-ICC) consists of adult progenitor cells. Immunohistochemistry revealed a reduction of neurons positive for neuronal nitric oxide synthase. The functional capabilities of the immature ICC and the regenerative capabilities of the adult progenitor cells need further study. The morphological features described here show that the loss of pacemaker activity is not associated with failure to develop a network of interstitial cells around AP but a failure to develop this network into fully functional pacemaker cells. The reduction in nitrergic innervation associated with the Ws mutation may be the result of a reduction in nitrergic neurons.

Interstitial cells of Cajal in the normal gut and in intestinal motility disorders of childhood

Interstitial cells of Cajal (ICCs) are pacemaker cells which are densely distributed throughout the whole gastrointestinal tract. ICCs have important functions in neurotransmission, generation of slow waves and regulation of mechanical activities in the gastrointestinal tract, especially for the coordinated gastrointestinal peristalsis. Therefore, a loss of ICCs could result in gastrointestinal motor dysfunction. In recent years c-kit labeling has been widely used to study pathological changes of ICCs in gastrointestinal motility disorders. Paediatric gastrointestinal motility disorders such as hypertrophic pyloric stenosis, Hirschsprung's disease, total colonic aganglionosis, hypoganglionosis, intestinal neuronal dysplasia, internal anal sphincter achalasia, megacystis microcolon intestinal hypoperistalsis syndrome have been reported to be associated with loss or deficiency of ICCs networks. This review describes the distribution of ICCs in the normal gastrointestinal tract and its altered distribution in intestinal motility disorders of childhood.

Interstitial cells of Cajal in health and disease. Part I: normal ICC structure and function with associated motility disorders

Ramon y Cajal (1852-1934) is considered to be one of the founders of the field of neuroscience. In 1911, he described interstitial neurons in the gut, noting that they were primitive accessory components that perhaps modify smooth muscle contraction, themselves subject to regulation from principle neurons. The accuracy of his description of their appearance and activities has led to these cells now being called the interstitial cells of Cajal (ICC). Thuneberg and Faussone-Pellegrini were instrumental in bringing these cells to the attention of gastroenterologists and pathologists in the early 1980s. Subsequently, the development of antibodies to c-kit has allowed routine identification of the ICC in pathology specimens. c-Kit is a transmembrane protein kinase which has as ligand stem cell factor and is involved in cell development in a variety of cell lineages. In the gut musculature, ICC and mast cells are the only cells that have prominent c-kit expression. The ICC are now known to play an important role in gut motility and absent or disordered ICC networks have been identified in a variety of motility disorders.

Exogenous serotonin regulates proliferation of interstitial cells of Cajal in mouse jejunum through 5-HT2B receptors

BACKGROUND & AIMS

Interstitial cells of Cajal (ICC) are required for normal gastrointestinal motility. Loss of ICC is associated with several motility disorders. The mechanisms modulating ICC survival and proliferation are poorly understood. This study aimed to establish whether 5-hydroxytryptamine (5-HT) plays a role in regulating ICC proliferation.

METHODS

Expression of 5-HT receptor mRNA was investigated in muscle strips, in purified populations of ICC, and in identified single cells. The effect of 5-HT(2B) receptor ligands on ICC numbers was studied in primary cell cultures. Proliferation of ICC was determined by counting Ki67-positive cells in culture.

RESULTS

Of the 5-HT receptors known to be involved in proliferation, 5-HT(2B) receptor mRNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in jejunal muscle, whereas 5-HT(1A), 5-HT(1D), and 5-HT(2C) receptor mRNAs were not. 5-HT(2B) receptor mRNA was found in single ICC and cells purified by flow cytometry. Exogenous 5-HT (1 micromol/L) increased (66% +/- 9%, P < .005) ICC numbers in culture. The 5-HT(2) receptor antagonist, ritanserin, and the 5-HT(2B) receptor antagonist, SB204741, inhibited the effect of 5-HT. The 5-HT(2B) receptor agonist BW 723C86 induced a concentration-dependent increase in ICC number (50% +/- 6% at 50 nM, P < .04) and increased ICC proliferation (25% +/- 3% vs 19 +/- 1% in controls, P < .03).

CONCLUSIONS

These studies establish that 5-HT(2B) receptors are expressed on ICC. Exogenous 5-HT regulates ICC numbers through 5-HT(2B) receptors in part by increasing ICC proliferation. The 5-HT(2B) receptor may serve as a novel pathway to regulate ICC numbers.

5-HT receptors on interstitial cells of Cajal, smooth muscle and enteric nerves

The majority of the body's serotonin (5-HT) is produced by the gastrointestinal tract. 5-HT has several functions in the gastrointestinal tract. 5-HT is a paracrine signalling molecule released from enterochromaffin cells, a survival and proliferating factor and a neurotransmitter. The actions of 5-HT are transduced by a large family of 5-HT receptors, several of which are expressed on different gastrointestinal cell types including enteric nerves, smooth muscle and interstitial cells of Cajal (ICC). This review will summarize recent advances in understanding the role of 5-HT in regulating function of ICC, and the expression and function of 5-HT receptors on muscle and enteric nerves in human tissue. Rodent ICC express several 5-HT receptors including 5-HT(2B) receptors which regulate ICC survival and proliferation. Human smooth muscle and enteric neurons also express several 5-HT receptor subtypes. Expression and function of these receptors is significantly different from small laboratory animals. 5-HT(7) receptor activation causes relaxation of muscle, whereas 5-HT(2B) receptors increase muscle activity. The 5-HT(4) receptor appears to mediate both inhibition and activation of smooth muscle involving myogenic as well as neural actions. Despite the abundant expression of 5-HT(3) receptors in the human enteric nervous system no functional correlate has been as yet demonstrated.

Regulation of interstitial cells of Cajal in the mouse gastric body by neuronal nitric oxide

The factors underlying the survival and maintenance of interstitial cells of Cajal (ICC) are not well understood. Loss of ICC is often associated with loss of neuronal nitric oxide synthase (nNOS) in humans, suggesting a possible link. The aim of this study was to determine the effect of neuronal NO on ICC in the mouse gastric body. The volumes of ICC were determined in nNOS(-/-) and control mice in the gastric body and in organotypic cultures using immunohistochemistry, laser scanning confocal microscopy and three-dimensional reconstruction. ICC numbers were determined in primary cell cultures after treatment with an NO donor or an NOS inhibitor. The volumes of myenteric c-Kit-immunoreactive networks of ICC from nNOS(-/-) mice were significantly reduced compared with control mice. No significant differences in the volumes of c-Kit-positive ICC were observed in the longitudinal muscle layers. ICC volumes were either decreased or unaltered in the circular muscle layer after normalization for the volume of circular smooth muscle. The number of ICC was increased after incubation with S-nitroso-N-acetylpenicillamine and decreased by N(G)-nitro-l-arginine. Neuronally derived NO modulates ICC numbers and network volume in the mouse gastric body. NO appears to be a survival factor for ICC.

Unique distribution of interstitial cells of Cajal in the feline pylorus

The feline gastrointestinal (GI) tract is an important model for GI physiology but no immunohistochemical assessment of interstitial cells of Cajal (ICC) has been performed because of the lack of suitable antibodies. The aim of the present study was to investigate the various types of ICC and associated nerve structures in the pyloric sphincter region, by using immunohistochemistry and electron microscopy to complement functional studies. In the sphincter, ICC associated with Auerbach's plexus (ICC-AP) were markedly decreased within a region of 6-8 mm in length, thereby forming an interruption in this network of ICC-AP, which is otherwise continuous from corpus to distal ileum. In contrast, intramuscular ICC (ICC-IM) were abundant within the pylorus, especially at the inner edge of the circular muscle adjacent to the submucosa. Similar distribution patterns of nerves positive for vesicular acetylcholine transporter (VAChT), nitric oxide synthase (NOS) and substance P (SP) were encountered. Quantification showed a significantly higher number of ICC-IM and the various types of nerves in the pylorus compared with the circular muscle layers in the adjacent antrum and duodenum. Electron-microscopic studies demonstrated that ICC-IM were closely associated with enteric nerves through synapse-like junctions and with smooth muscle cells through gap junctions. Thus, for the first time, immunohistochemical studies have been successful in documenting the unique distribution of ICC in the feline pylorus. A lack of ICC-AP guarantees the distinct properties of antral and duodenal pacemaker activities. ICC-IM are associated with enteric nerves, which are concentrated in the inner portion of the circular muscle layer, being part of a unique innervation pattern of the sphincter.

Medical treatment of infantile hypertrophic pyloric stenosis: should we always slice the "olive"?

BACKGROUND/PURPOSE

Laparoscopic pyloromyotomy has recently gained wide acceptance as the optimum treatment of infantile hypertrophic pyloric stenosis (IHPS). However, medical treatment may be superior to laparoscopic surgery in invasiveness. The efficacy of our regimen of intravenous atropine therapy for IHPS was assessed in comparison with surgical treatment.

METHODS

Medical treatment was initially chosen for 52 (61%) of 85 infants with IHPS at our institute between 1996 and 2004. Atropine was given intravenously at 0.01 mg/kg 6 times a day before feeding. When vomiting ceased and the infants were able to ingest 150 mL/kg per day of formula after stepwise increases in the feeding volume, they were given 0.02 mg/kg atropine 6 times a day orally, and the dose was decreased stepwise.

RESULTS

Of the 52 patients, 45 (87%) ceased projectile vomiting with treatment using intravenous (median, 7 days) and subsequent oral (median, 44 days) atropine administration. The median hospital stay was 13 days (6-36), and no significant complications were encountered during atropine therapy. The remaining 7 patients required surgery. Of 40 who underwent surgery, 4 had wound infections and 1 with hemophilia had postoperative hemorrhagic shock. The patients who underwent successful atropine therapy had body weights comparable with those who underwent surgery at the age of 1 year.

CONCLUSIONS

The high success rate of intravenous atropine therapy for IHPS suggests that this therapy is an effective alternative to pyloromyotomy if the length of the hospital stay and the necessity of continuing oral atropine medication are accepted.

The pylorus

The pylorus controls the flow between a reservoir dedicated to mechanical and chemical digestion (the stomach) and a conduit dedicated to the absorption of nutrients (the intestines). The pylorus adjusts gastric outflow resistance to physiological needs. It allows the outflow of isotonic fluids yet selectively retains particles too large for delivery to the intestines and in concert with the antrum further processes them (gastric sieving). Unlike most gut sphincters, the pylorus, at least of man, maintains a patent lumen most of the time. It only intermittently becomes a tightly closed barrier that arrests all flow out of and into the stomach. The geometry of the pylorus changes dramatically from the relaxed open state to closure. Pyloric closure involves contraction of its proximal and distal muscle loops, and occlusion of its lumen by mucosal folds. Current studies that combine pressure recordings with imaging by magnetic resonance imaging or ultrasound and fluid-mechanical analysis shed new light on the role of the pylorus in gastric emptying and digestion. Much has been learned in recent years on the innervation of the normal pylorus particularly from studies on infantile hypertrophic stenosis, and attempts are being made to treat gastroparesis by interventions on the pylorus.

New monoclonal antibody (AIC) identifies interstitial cells of Cajal in the musculature of the mouse gastrointestinal tract

Interstitial cells of Cajal (ICC) are pacemaker cells for the spontaneous muscular contractions and neuromodulators that mediate neurotransmission from enteric neurons to smooth muscle cells in the gastrointestinal (GI) tract. They express c-Kit, and the antibody for c-Kit (especially ACK2) has been a useful tool for functional and morphological studies. ACK2, however, does not work on tissues fixed with paraformaldehyde, and not all ICC express c-Kit in human. Therefore, in order to find a new marker of ICC and/or new antibody resisting aldehyde fixation, we produced a new monoclonal antibody that identifies ICC and then investigated the properties of its antigen. Isolated ICC were used for immunization. Hybridomas fused with myeloma SP2 were screened by immunohistochemistry. ACK2 and each antibody were applied on serial sections, and the clone producing anti-ICC antibody (AIC) that stains ICC was established. The distribution of AIC immunopositive cells was examined in other organs and also GI muscles of W/Wv mice. The biochemical properties were studied using dot blot analysis. AIC recognized ICC; however, distribution of immunopositive cells in W/Wv mice and other organs was different from that of c-Kit. The immunoreactivity was stable for paraformaldehyde but was blocked by either Triton X-100 or SDS. In conclusion, new antibody AIC recognized ICC but the antigen was not c-Kit, which confirms the existence of good markers of ICC besides c-Kit. Although the antigen has not been isolated, AIC is suitable for morphological study and is useful for investigation of ICC in c-Kit mutants.

American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis

This literature review and the recommendations herein were prepared for the American Gastroenterological Association Clinical Practice Committee. The paper was approved by the Committee on May 16, 2004, and by the AGA Governing Board on September 23, 2004.

Single-nucleotide promoter polymorphism alters transcription of neuronal nitric oxide synthase exon 1c in infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS), characterized by enlarged pyloric musculature and gastric-outlet obstruction, is associated with altered expression of neuronal nitric oxide synthase (nNOS). Here we have studied molecular mechanisms by which nNOS gene expression is altered in pyloric tissues of 16 infants with IHPS and 9 controls. A significant decreased expression of total nNOS mRNA was found by quantitative RT-PCR in IHPS after normalization against GAPDH, which predominantly affected exon 1c with a reduction of 88% compared with controls (P < 0.001). After normalization against the neuronal-specific gene PGP9.5, expression of exon 1c was still decreased (P < 0.001), whereas expression of exon 1f was increased significantly (P = 0.001), indicating a compensatory up-regulation of this nNOS mRNA variant. DNA samples of 16 IHPS patients and 81 controls were analyzed for nNOS exon 1c promoter mutations and single-nucleotide polymorphism (SNP). Sequencing of the 5'-flanking region of exon 1c revealed mutations in 3 of 16 IHPS tissues, whereas 81 controls showed the wild-type sequence exclusively. Carriers of the A allele of a previously uncharacterized nNOS exon 1c promoter SNP (-84G --> A) had increased risk for development of IHPS (odds ratio, 8.0; 95% confidence interval, 2.5-25.6). Reporter gene assays revealed an unchanged promoter activity for mutations but a approximately 30% decrease for the -84A SNP (P < 0.001). In summary, our findings indicate that genetic alterations in the nNOS exon 1c regulatory region influence expression of the nNOS gene and may contribute to the pathogenesis of IHPS.

Hypertrophic pyloric stenosis in infants: US evaluation of vascularity of the pyloric canal

PURPOSE

To determine if there is increased flow to the pylorus in infants with hypertrophic pyloric stenosis (HPS) and, if so, whether the flow is localized to the muscle layer, mucosal layer, or both.

MATERIALS AND METHODS

Seventy-five infants examined for clinical suspicion of HPS were prospectively recruited for the study. Color scale was standardized at 4.2-4.4 cm/sec. Color Doppler flow at ultrasonography (US) was graded as follows: Grade 1 meant no signal; grade 2, two to five flow signals; and grade 3, extensive or continuous flow. Flow to the muscle or mucosal layer was documented and confirmed with spectral analysis. Infants without HPS served as control patients. Descriptive analyses were conducted to assess the demographic data and US results. Significance was assessed with chi2 or t tests. P <.05 was considered to indicate a significant difference.

RESULTS

HPS was present in 41 infants with a mean age of 5 weeks +/- 2.0 (SD). Their mean flow grade was 2.80 +/- 0.4 in muscle and 2.88 +/- 0.4 in mucosa. HPS was not present in 34 infants with a mean age of 5.9 weeks +/- 4.5. Their mean flow grade was 1.26 +/- 0.5 in muscle and 1.15 +/- 0.5 in mucosa (P <.001). There was no significant difference in flow grades when the dimensions of the pyloric muscle and mucosa were compared. There was no significant difference in age between the HPS and control patient groups.

CONCLUSION

Increased flow accompanies and may conceivably represent an integral component of the changes that occur with infantile HPS.

Differential gene expression in the murine gastric fundus lacking interstitial cells of Cajal

BACKGROUND

The muscle layers of murine gastric fundus have no interstitial cells of Cajal at the level of the myenteric plexus and only possess intramuscular interstitial cells and this tissue does not generate electric slow waves. The absence of intramuscular interstitial cells in W/WV mutants provides a unique opportunity to study the molecular changes that are associated with the loss of these intercalating cells.

METHOD

The gene expression profile of the gastric fundus of wild type and W/WV mice was assayed by murine microarray analysis displaying a total of 8734 elements. Queried genes from the microarray analysis were confirmed by semi-quantitative reverse transcription-polymerase chain reaction.

RESULTS

Twenty-one genes were differentially expressed in wild type and W/WV mice. Eleven transcripts had 2.0-2.5 fold higher mRNA expression in W/WV gastric fundus when compared to wild type tissues. Ten transcripts had 2.1-3.9 fold lower expression in W/WV mutants in comparison with wild type animals. None of these genes have ever been implicated in any bowel motility function.

CONCLUSIONS

These data provides evidence that several important genes have significantly changed in the murine fundus of W/WV mutants that lack intramuscular interstitial cells of Cajal and have reduced enteric motor neurotransmission.

Novel human and mouse genes encoding a shank-interacting protein and its upregulation in gastric fundus of W/WV mouse

BACKGROUND AND AIMS

A division of labor exists between different classes of interstitial cells of Cajal (ICC) in the gastrointestinal tract. In the stomach and small intestine, ICC at the level of the myenteric plexus (IC-MY) act as slow wave pacemaker cells, whereas intramuscular ICC (IC-IM) in the stomach act as intermediaries in enteric motor neurotransmission. The muscle layers of the gastric fundus do not have IC-MY, therefore electric slow waves are not generated. Intramuscular ICC are absent in the gastric fundus of W/WV mutant mice, and excitatory and inhibitory motor nerve responses are reduced in these tissues. The absence of IC-IM in W/WV mutants in the fundus provides a unique opportunity to study the molecular changes that are associated with the loss of these cells.

METHODS

The tissue gene expression of wild-type and W/WV mice from gastric fundus was assayed using a murine microarray chip analysis displaying a total of 8734 elements.

RESULTS

Twenty-one queries were differentially expressed in wild-type and W/WV mice. One candidate gene, encoding a novel protein homologous to rat Shank-interacting protein (Sharpin) was significantly upregulated in fed and starved W/WV mice. The full-length clone of the murine gene and its human counterpart were isolated and designated as Shank-interacting protein-like 1 (SIPL1). Human SIPL1 complementary DNA encodes a protein of 345 amino acids. This gene was localized to chromosome 8. SIPL1 was abundantly expressed in human stomach and small intestine, and scarcely expressed in cecum and rectum.

CONCLUSIONS

Gene analysis showed that SIPL1 differentially express in the gastric fundus of normal and W/WV mice. The upregulation of SIPL1 in the fundus of W/WV mice, and expression in the upper gastrointestinal tract suggest that the SIPL1 gene could be associated with ICC function in mice and humans.

Localization of protein kinase C theta immunoreactivity to interstitial cells of Cajal in guinea-pig gastrointestinal tract

In the gastrointestinal tract, interstitial cells of Cajal (ICC) are located between nerve fibres and muscle cells and have a role in neuromuscular transmission and muscle contractility. Protein kinase C (PKC) is involved in modulation of muscle contractility by neurotransmitters, but it is not known if PKC has a role in ICC. There are 11 different PKC isoforms. The presence of PKC isoforms in ICC in guinea-pig gastrointestinal tract was examined using fluorescence immunohistochemistry and confocal microscopy. Segments of guinea-pig stomach, duodenum, ileum, proximal and distal colon were fixed in zambonis fixative. Frozen sections and wholemounts were incubated with anti-PKC antibodies (alpha, beta, delta, epsilon, gamma, iota, lambda, mu, theta) followed by fluorescent secondary antibody. Only PKC theta (theta) immunoreactivity was found in ICC. None of the other PKC isoforms (alpha, beta, delta, epsilon, gamma, iota, lambda, mu) localized to the ICC. PKC theta immunoreactivity was prominent in ICC located between the circular and longitudinal muscle layers (ICC-MY) in all regions except stomach and within the circular muscle (ICC-IM) in the large intestine. PKC theta was not present in ICC in the deep muscular plexus in either duodenum or ileum. PKC theta immunoreactivity was present in the cell body and proximal processes of the ICC. The cells containing PKC theta also contained cKit confirming the cells were ICC. ICC-MY in the ileum also contained the neurokinin (NK) 1 receptor. In conclusion, PKC theta is present in pacemaker ICC, but its function is not yet known. Functional studies will be needed to determine the role of this kinase in ICC. Knowing the second messenger cascades and being able to manipulate subpopulations of ICC will add to our understanding of the molecular and cell biology of ICC networks within the gastrointestinal tract and may ultimately help in understanding the aetiology of some gastrointestinal motor pathologies.

Role of interstitial cells of Cajal in motility disorders of the bowel

OBJECTIVE

Idiopathic intestinal pseudo-obstruction is characterized by the failure of the intestinal tract to propel its contents appropriately. This leads to signs and symptoms of bowel obstruction and, in the absence of an associated systemic disorder or the administration of drugs known to result in bowel dysmotility, is termed chronic idiopathic intestinal pseudo-obstruction (CIIP). Histopathologically, patients with CIIP can be characterized as having either myopathic or neuropathic forms, but the large majority of patients do not show any specific histological changes. Interstitial cells of Cajal (ICC) have been shown to be the pacemaker cells of the bowel and have been implicated in the pathogenesis of CIIP. The aim of this study was to compare the number and distribution patterns of c-kit+ ICC in CIIP in patients with mechanical bowel obstruction, other bowel motility disorders, and normal controls.

METHODS

Six patients with CIIP, six age-matched normal controls, nine patients with mechanical bowel obstruction, and 18 patients with other motility disorders (non-CIIP), including 10 with secondary intestinal pseudo-obstruction, were studied. Toluidine blue, Masson's trichrome, and S-100 immunostaining were performed in all subjects. The ICC were identified by an indirect immunoperoxidase method using a polyclonal c-kit antibody.

RESULTS

All six patients with CIIP showed total absence of c-kit+ ICC. A subject with neonatal meconium ileus in the non-CIIP group showed patchy areas devoid of c-kit+ ICC amid normal areas. The c-kit+ ICC had a normal number and distribution pattern in all patients with mechanical obstruction and in the remaining 17 non-CIIP subjects.

CONCLUSIONS

It seems that CIIP is characterized by a total loss of c-kit+ ICC. ICC may play an important role in the etiopathogenesis of CIIP and transient neonatal meconium syndrome, and staining for c-kit receptor may be very useful in the evaluation of motility disorders of the bowel.

Long-term regeneration of abdominal vagus: efferents fail while afferents succeed

Vagal afferents regenerate, by 18 weeks after subdiaphragmatic transection, to reinnervate the gut and to differentiate into the two types of terminals normally found in the smooth muscle wall of the gastrointestinal (GI) tract (Phillips et al. [2000] J Comp Neurol. 421:325-346). Regeneration, however, is neither complete nor entirely accurate by 18 weeks. Moreover, the capacity of the vagal efferents to reinnervate the GI tract under comparable conditions has not been evaluated. Therefore, to determine whether a more extended postaxotomy survival interval would (1). result in more extensive reinnervation of smooth muscle, (2). facilitate correction of the inaccuracies of the regenerated axons and terminals, and (3). yield motor as well as sensory reinnervation of GI targets, Sprague-Dawley rats received either complete subdiaphragmatic vagotomies (n = 18) or sham surgeries (n = 12). Physiological endpoints that might normalize as vagal elements regenerated, including body weight, daily food intake, size of first daily meal, and metabolic efficiency, were monitored. At 45 weeks after the vagotomies, the animals were randomly assigned to afferent (wheat germ agglutinin-horseradish peroxidase) or efferent (cholera toxin subunit B-horseradish peroxidase) mapping conditions, and labeled axons and terminals in the stomach and first 8 cm of the small intestine were inventoried in whole-mounts. Afferent regeneration was more extensive at 45 weeks than previously observed at 18 weeks after surgery; however, the amount of GI innervation was still not comparable to the intact pattern of the sham rats. Furthermore, abnormal patterns of sensory organization occurred throughout the reinnervated field, with small bundles of axons forming complex tangles and some individual axons terminating in ectopic locations. The presence of growth cone profiles suggested that vagal reorganization was ongoing even 45 weeks after surgery. In contrast to this relatively extensive, albeit incomplete, sensory reinnervation of the gut, motor fibers had failed to reinnervate the GI tract. Thus, dramatic differences exist in the regenerative capacities of the sensory and motor arms of the vagus under the same surgical and maintenance conditions. Furthermore, the functional measures of disordered energy regulation did not normalize over the 45 weeks during which afferent but not efferent innervation was restored.

Physiology and pathophysiology of the interstitial cell of Cajal: from bench to bedside. II. Gastric motility: lessons from mutant mice on slow waves and innervation

The stomach harbors a network of interstitial cells of Cajal (ICC) associated with Auerbach's plexus as well as intramuscular ICC within the muscle layers that make close apposition contact with nerve varicosities. ICC are critical for slow-wave generation, making ICC the pacemaker cells of the gut, allowing rhythmic peristaltic motor patterns in the mid- and distal stomach. ICC also play a role in neurotransmission, but its importance relative to direct muscle innervation is still under investigation. The role of ICC in many control functions of gastric motility in humans needs further examination. The pathophysiology of ICC in disease can be partially assessed by immunohistochemistry and electron microscopy on tissue samples. Electrogastrogram measurements may also play a role, but this technique needs further refinement. Communication between ICC and muscle may involve electrical coupling, metabolic coupling through gap junctions, or secretion of nitric oxide or carbon monoxide.

Selective neurotrophin deficiency in infantile hypertrophic pyloric stenosis

BACKGROUND/PURPOSE

Increasing evidence suggests that the enteric nervous system is under the control of neurotrophins. Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5), promote differentiation, growth, and survival of various central and peripheral nervous system neurons. The biological effects of neurotrophins are mediated by the interactions with high-affinity tyrosine kinase receptors (TrkA, TrkB, TrkC). Recently, abnormalities of intramuscular innervation have been reported in infantile hypertrophic pyloric stenosis (IHPS). To further understand the reported abnormalities in pyloric innervation in IHPS, the authors analyzed the expression of Trk receptors and the neurotrophins content in IHPS.

METHODS

Full-thickness muscle biopsy specimens were obtained from 8 IHPS patients (age range, 23 to 41 days) at pyloromyotomy and from 8 age-matched controls without gastrointestinal disease at autopsy performed within 12 hours after death. Indirect immunohistochemistry was performed using ABC (Avidin Biotin peroxidase Complex) method with anti-Trk specific antibodies (A,B,C). Quantitative analysis was performed using sandwich-type ELISA for NGF, BDNF, NT-3, and NT-4/5.

RESULTS

The intensity of staining of the myenteric plexus for TrkA, TrkB, and TrkC was similar among IHPS and controls. There was a lack of TrkA-positive nerve fibers in IHPS compared with controls. The quantity of total NGF, NT-3, and BDNF in IHPS was significantly lower than in controls.

CONCLUSIONS

The reduced production of neurotrophins in IHPS may be responsible for the delay in the functional and structural maturation of pyloric innervation in IHPS. The lack of TrkA-positive nerve fibers in pyloric muscle may explain the abnormal intramuscular innervation in IHPS.

Three-dimensional morphology of c-Kit-positive cellular network and nitrergic innervation in the human gut

CONTEXT

-c-Kit-positive interstitial cells of Cajal (ICC) appear to play a key role in the normal motility function and development of intestine. Nitric oxide is considered to be the most important messenger of inhibitory nonadrenergic, noncholinergic nerves in the enteric nervous system.

OBJECTIVES

The aims of this study were to examine the distribution of nitrergic innervation and ICCs in normal human bowel and to demonstrate interconnections between ICCs and nitrergic nerves and smooth muscle fibers using histochemical and immunohistochemical double-staining methods with a whole-mount preparation technique and confocal laser scanning microscopy.

METHODS

Full-thickness small and large bowel specimens were obtained at autopsy from 18 children who died of nongastrointestinal diseases. A whole-mount preparation was performed for all specimens, and double staining was carried out with nicotinamide adenine dinucleotide phosphate (reduced form, NADPH)-diaphorase and c-Kit immunohistochemistry. Double immunofluorohistochemistry with neuronal nitric oxide synthase and c-Kit using confocal laser scanning microscopy was also performed in all specimens.

RESULTS

The whole-mount preparation facilitated 3-dimensional visualization of the meshlike network of NADPH-diaphorase-positive nerve fibers in the myenteric plexus surrounded by a reticular network of c-Kit-positive ICCs. The dense c-Kit-positive cellular network located between longitudinal and circular muscle layers and at the innermost part of circular muscle layer intermingled with the myenteric plexus. Short, fine processes of ICCs made connections with the muscle fibers and c-Kit-positive cells.

CONCLUSIONS

The development of double-NADPH-diaphorase histochemistry and c-Kit immunohistochemistry staining technique in a whole-mount preparation provides an easy and useful method for investigating the association between c-Kit-positive cellular network and nitrergic neuronal network in the human bowel wall. The characteristic profiles of the c-Kit-positive cellular network and nitrergic neuronal network and their relationship with the smooth muscle fibers provide a morphologic basis for investigating intestinal motility disorders.

Infantile hypertrophic pyloric stenosis: a comparative study of pyloric traumamyoplasty and Fredet-Ramstedt pyloromyotomy

PURPOSE

The aim of this study was to compare the incidence of surgical complications (duodenal perforation, postoperative vomiting, wound infection or dehiscence, incisional hernia) between 2 different surgical techniques for the resolution of hypertrophic pyloric stenosis in children.

METHODS

A clinically controlled, randomized study with follow-up from 24 to 36 months was conducted. One hundred children between 15 days and 2 months old, who underwent surgical resolution of hypertrophic pyloric stenosis, were put randomly into 2 groups: I, pyloric traumamyoplasty (n = 43); II, Fredet-Ramstedt pyloromyotomy (n = 57). Both groups were controlled for the main demographic variables. Postoperative follow-up was blind for the surgical team. Statistical analysis was done with simple frequencies, percentages, Student's t test, and chi(2).

RESULTS

There was not a single case of duodenal perforation, incomplete pyloromyotomy, wound infection, dehiscence, or incisional hernia in any group (P value, not significant). Postoperative emesis was present in 8 patients, uniformly distributed between groups. The operating room time for traumamyoplasty was 39.3 +/- 16.4 minutes versus 54 +/- 16.4 minutes for pyloromyotomy (P =.0003).

CONCLUSIONS

This controlled study proves that traumamyoplasty is a simple procedure, quicker to perform, and as safe as pyloromyotomy for the treatment of infantile hypertrophic pyloric stenosis in children. For these reasons, the authors believe it should be considered as an alternative.

Differential gene expression in the small intestines of wildtype and W/W(V) mice

Much of the evidence demonstrating the role of interstitial cells of Cajal (ICC) in pacemaking and neurotransmission in the gastrointestinal tract comes from studies of W/W(V) mice. These animals have few pacemaker ICC in the small bowel due to reduced functional Kit protein. We examined gene expression in the small intestines of wildtype and W/W(V) mice. RNA expression in the jejunums of wildtype and W/W(V) mutants was studied using a differential gene expression

METHOD

Seven known genes were differentially expressed in wildtype and W/W(V) mice. COX7B (cytochrome c oxidase, subunit VIIb) and SORCIN (encoding multidrug-resistance complex, class 4) were suppressed in both fed and fasted W/W(V) mice. Expression of another five genes was increased in W/W(V) mice: ADA (adenosine deaminase), MDH1 (malate dehydrogenase), RPL-8 (ribosomal protein L8), SPTB2 (spectrin, nonerythroid, beta subunit), and p6-5 (encoding phosphorylcholine [PC] T-cell suppressor factor [TsF]). Differential expression was the same in fasted and fed animals, suggesting that the differences were independent of the dietetic state. We conclude that several genes are differentially expressed in the small intestines of W/W(V) mice where the major lesion is loss of pacemaker ICC. Differential gene display may help develop a molecular profile of motility disorders in which ICC are lost.

Nitric oxide synthase is absent in only a subset of cases of pyloric stenosis

PURPOSE

The aim of this study was to study nitric oxide synthase (NOS) immunohistochemistry in the pyloric muscle and establish the role of nitric oxide in pyloric stenosis.

METHODS

Pyloric muscle biopsy specimens were obtained from 20 patients with pyloric stenosis during pyloromyotomy. Ten control specimens without pyloric disease were obtained from autopsy performed less than 4 hours after death on age-matched babies who died of other causes. Tissues were fixed in 4% paraformaldehyde immediately. A monoclonal antibody against the neuronal form of NOS (bNOS) was used for immunohistochemistry.

RESULTS

Immunohistochemistry showed activity of bNOS in the control specimens and some pyloric stenosis specimens. This shows that NOS is present in the pylorus in normal cases as well as in a few cases of pyloric stenosis.

CONCLUSIONS

NOS deficiency leading to lack of locally available nitric oxide causes a failure of smooth muscle relaxation. This may account for the cause of pyloric stenosis in infants. However, this study shows that this is true probably only in a subset of cases. The etiology of pyloric stenosis may still be multifactorial. Further investigations are required regarding the etiology of pyloric stenosis. J Pediatr Surg 36:616-619.

Three-dimensional morphology of gut innervation in total intestinal aganglionosis using whole-mount preparation

BACKGROUND

Total intestinal aganglionosis (TIA) is a rare form of Hirschsprung's disease (HD). The aim of this study was to examine the 3-dimensional morphology of the myentric plexus of the entire gastrointestinal tract in a newborn with total intestinal aganglionosis.

METHODS

Whole-mount preparations were made of the entire gastrointestinal tract using NADPH-diaphorase histochemistry and c-kit (a marker of interstitial cells of Cajal) immunohistochemistry.

RESULTS

Whole-mount preparations of the esophagus, stomach, and duodenum showed 3-dimensional morphology of the myenteric plexus forming a meshlike network of nerve fibers, connected to each other and to ganglia. There were large numbers of NADPH-diaphrase-positive nerve fibers between the muscle fibers in the circular muscle layer. In esophagus, stomach, and duodenum, c-kit-positive interstitial cells of Cajal (ICC) formed a 3-dimensional network between the two muscle layers and also were abundant within the circular muscle layer. In the jejunum, ileum, and colon, the myenteric plexus was absent and was replaced by hypertrophic nerve bundles that stained weakly with NADPH-diaphrase. Circular muscle layer completely lacked NADPH-diaphrase-positive nerve fibers. The c-kit-positive ICCs in the jejunum, ileum, and colon were sparse and localized mainly around the nerve trunks between the circular and longitudinal muscle layers.

CONCLUSIONS

Whole-mount preparation is an elegant 3-dimensional technique in which the relationship of branching and interconnecting nerve fibers to each other and to muscle can be seen clearly. Absence of myenteric plexus, lack of nitrergic innervation, and depletion of interstitial cells of Cajal in the bowel wall throughout the small and large bowel contribute to the inability of the smooth muscle to relax, thereby causing lack of peristalsis in TIA.

Experimental hypertrophy of myenteric neurones in the pig: a morphometric study

Muscular hypertrophy in the ileum of two pigs aged 6 weeks was induced using two different surgical techniques, narrowing of the gut circumference (mechanical stenosis) and segmental reversal of an ileal loop which results in a persistent antiperistalsis of that segment (functional stenosis). These pigs were sacrificed 5-6 weeks postoperatively. Cross sections through the gut wall at various distances from the operation sites revealed marked muscular hypertrophy in the pre-stenotic regions and in the reversed segment. Whole mounts from pre- and post-stenotic, as well as reversed ileal regions, were silver- impregnated. The corresponding ileal region of a third, nonoperated pig served as control. Using a computer-aided morphometric device, somal areas of five morphological neurone types were measured at various distances orally and anally from the operation sites and along the control ileum. Values between hypertrophic and nonhypertrophic zones as well as between two corresponding zones of nonoperated ileum were compared statistically. Along the control ileum, values revealed no differences in soma sizes. Within the experimentally altered material, somal areas of type VI neurones showed marked hypertrophy related to the sites of muscular hypertrophy whereas the other types remained constant throughout (II, IV in segmental reversal) or showed slightly larger somal areas within the post-stenotic, nonhypertrophied zones (I, V, IV in stenosis). Additionally, within the reversed segment, neuronal perikarya of type I, II, IV and V neurones were larger as compared to the neighbouring regions. However, this enlargement of perikarya within the reversed segment may not be correlated with muscular hypertrophy but rather with the transections of intramural axons before reversing this segment. The results suggest that morphologically distinct neurone types may play different roles within the mechanically stressed small intestine and possibly also in the coordination of normal muscular function.

Interstitial cells of Cajal in human gut and gastrointestinal disease

This paper reviews the distribution of interstitial cells of Cajal (ICC) in the human gastrointestinal (GI) tract, based on ultrastructural and immunohistochemical evidence. The distribution and morphology of ICC at each level of the normal GI tracts is addressed from the perspective of their functional significance. Alterations of ICC reported in achalasia of cardia, infantile hypertrophic pyloric stenosis, chronic intestinal pseudoobstruction, Hirschsprung's disease, inflammatory bowel diseases, slow transit constipation, and some other disorders of GI motility as well as in gastrointestinal stromal tumors are reviewed, with emphasis on the place of ICC in the pathophysiology of disease.

Long-term effects of pyloromyotomy on pyloric motility and gastric emptying in humans

OBJECTIVE

The aim of this study was to determine the long term effects of pyloromyotomy for infantile hypertrophic pyloric stenosis (IHPS) on gastric emptying and pyloric motility.

METHODS

Concurrent measurements of gastric emptying and antropyloroduodenal pressures were performed in six volunteers (aged 24-26 yr) who had had pyloromyotomy performed in infancy because of IHPS, and in six normal subjects. Subjects were studied on 2 days, once sitting and once in the left lateral position. Gastric emptying of 300 ml 25% dextrose labeled with 20 MBq 99mTc sulfur colloid was measured. Antropyloroduodenal motility was evaluated with a sleeve/multiple sidehole manometric assembly, which was also used to deliver an intraduodenal triglyceride infusion at 1.1 kcal/min for 60 min, starting 30 min after ingestion of the dextrose.

RESULTS

In both body positions, gastric emptying and intragastric distribution of the drink did not differ between the two groups. In both groups and postures, the amount emptied was less during intraduodenal lipid infusion. The number (p<0.01) and amplitude (p<0.02) of isolated pyloric pressure waves (IPPWs) was greater in the control subjects, whereas basal pyloric pressure was greater in the pyloromyotomy subjects (p<0.02). In both groups, the rate of gastric emptying in the sitting position was related to the number of IPPWs (r> or =0.40, p<0.05), but not to basal pyloric pressure.

CONCLUSIONS

These results indicate that, in adults who have had pyloromyotomy for IHPS in infancy, patterns of pyloric motility are abnormal; pyloric tone is higher, whereas the number and amplitude of phasic pyloric pressure waves are less. In contrast, the overall rate of gastric emptying of a nutrient liquid meal is normal. These observations are consistent with the concept that the stomach has the capacity to compensate for changes in pyloric motility to minimize effects on gastric emptying.

Interstitial cells of Cajal in human gut and gastrointestinal disease

This paper reviews the distribution of interstitial cells of Cajal (ICC) in the human gastrointestinal (GI) tract, based on ultrastructural and immunohistochemical evidence. The distribution and morphology of ICC at each level of the normal GI tracts is addressed from the perspective of their functional significance. Alterations of ICC reported in achalasia of cardia, infantile hypertrophic pyloric stenosis, chronic intestinal pseudoobstruction, Hirschsprung's disease, inflammatory bowel diseases, slow transit constipation, and some other disorders of GI motility as well as in gastrointestinal stromal tumors are reviewed, with emphasis on the place of ICC in the pathophysiology of disease.

Plasticity in the enteric nervous system

Enteric ganglia can maintain integrated functions, such as the peristaltic reflex, in the absence of input from the central nervous system, which has a modulatory role. Several clinical and experimental observations suggest that homeostatic control of gut function in a changing environment may be achieved through adaptive changes occurring in the enteric ganglia. A distinctive feature of enteric ganglia, which may be crucial during the development of adaptive responses, is the vicinity of the final effector cells, which are an important source of mediators regulating cell growth. The aim of this review is to focus on the possible mechanisms underlying neuronal plasticity in the enteric nervous system and to consider approaches to the study of plasticity in this model. These include investigations of neuronal connectivity during development, adaptive mechanisms that maintain function after suppression of a specific neural input, and the possible occurrence of activity-dependent modifications of synaptic efficacy, which are thought to be important in storage of information in the brain. One of the applied aspects of the study of plasticity in the enteric nervous system is that knowledge of the underlying mechanisms may eventually enable us to develop strategies to correct neuronal alterations described in several diseases.

Guide to the identification of interstitial cells of Cajal

The interstitial cell of Cajal, abbreviated ICC, is a specific cell type with a characteristic distribution in the smooth muscle wall throughout the alimentary tract in humans and laboratory mammals. The number of publications relating to ICC is rapidly increasing and demonstrate a rich variation in the structure and organization of these cells. This variation is species-, region-, and location-dependent. We have chosen to define a "reference ICC," basically the ICC in the murine small intestine, as a platform for discussion of variability. The growing field of ICC markers for light and electron microscopy is reviewed. Although there is a rapidly increasing number of approaches applicable to bright field and fluorescence microscopy, the location of markers by electron microscopy still suffers from inadequate preservation of ultrastructural detail. Finally, we summarize evidence related to ICC ultrastructure under conditions differing from those of the normal, adult individual (during differentiation, in pathological conditions, transplants, mutants, and in cell culture).

Control systems of gastrointestinal motility are immature at birth in dogs

Networks of interstitial cells of Cajal (ICC) in the myenteric plexus (Myp) or circular muscle (CM) function as pacemakers for gastrointestinal slow waves. ICC in contact with muscle and closely associated with nerves in the CM may mediate inhibitory neurotransmission. We wondered if ICC in Myp and CM and their connections are immature at birth and mature first in the proximal gut in association with nerves. Tissues from lower esophageal sphincter (LES), pylorus (PYL), small intestine (SI) and colon (CO) of 18 term fetal dogs taken from six females were fixed and prepared for ultrastructural examination and studied. Ganglia were present where expected in the Myp and submucous plexus (SMP). ICC cells were present in the Myp of PYL, SI and CO and appeared to have normal relationships to the outer border of CM as in adults. ICC in CM were found associated with nerves in the LES and in PYL, but not in SI or CO. However, axons in CM were everywhere usually free of glial covering, indicating ongoing migration or development. No organized deep muscular plexus (DMP) in SI or submuscular plexus (SP) in colon was present. Visible gap junctions were absent everywhere except for very rare ones between circular muscle cells. We conclude that at birth the neural and ICC networks of CM are more immature in intestine and colon than in oesophagus and stomach. Development of nerve and ICC of CM in oesophagus and stomach apparently precedes that in the remaining gut. However networks in these regions have not achieved adult organization and ICC and smooth muscle cells are anatomically poorly coupled. These findings suggest the reasons that gut motility at birth will not be adult in pattern are because ICC, nerve and muscle control systems are not fully differentiated. Further developmental delays in ICC and nerve maturation could have serious consequences for feeding of infant animals.

Interstitial cells of Cajal as precursors of gastrointestinal stromal tumors

Interstitial cells of Cajal (ICC) are implicated in the regulation of gut peristalsis and are immunostained by antibodies against Kit (CD117), a tyrosine kinase receptor. Most gastrointestinal mesenchymal tumors (GIMTs) are of uncertain histogenesis, although many are CD34-positive. CD34 was found to colocalize with vimentin (Vim) and the Kit-positive networks of cells within and around neural plexi, indicating that ICC can be Vim- and CD34-positive. ICCs appear to be the only Kit+CD34+Vim+ cell in the gut. Formalin-fixed, paraffin-embedded tissues from 43 GIMTs were immunostained for Kit, CD34, Vim, PGP 9.5 (PGP, a neural marker), muscle-specific actin (MSA), and other markers including desmin (Des). Eight tumors were myoid (MSA+Des+Vim-Kit-CD34-), and one was a schwannoma (PGP+S100+Vim+Kit-CD34-), but 34 tumors were of uncertain histogenesis (gastrointestinal stromal tumors, GIST), exhibiting neither a complete myoid nor a schwannian immunophenotype. All 34 were Vim+, and 33/34 were either Kit (n = 30) or CD34 (n = 23) immunoreactive. Of these 34 GIST, 24 were negative for all myoid and neural markers, 6 were PGP+S100-, and 4 were MSA+Des-. The Kit+CD34+Vim+ immunophenotype of GIST suggests that they originate from, or have differentiated into, ICC-like cells; the term ICC tumor (ICCT) is suggested. Kit is a more sensitive marker than CD34 for ICCT, but both are required in tumor identification. All clinically malignant GISTs were pathologically malignant (size, mitoses) but also showed loss of either CD34 or Kit. "Blind" examination of electron micrographs in 10 tumors showed them to be heterogeneous. Some had features seen in normal ICC, but cells could not be positively identified as being adult ICC. GIMT may therefore be classifiable into those with pure myoid, schwannian (or neural) differentiation, but the majority are of ICC origin or show ICC differentiation immunophenotypically (ICCT).

Development of pacemaker activity and interstitial cells of Cajal in the neonatal mouse small intestine

Intestinal motor patterns are not well developed in premature infants. Similarly, in neonatal mice, irregular motor patterns were observed. Pacemaker cells, identified in the small intestine as interstitial cells of Cajal (ICCs) associated with Auerbach's plexus (ICC-APs), contribute to the generation of peristaltic movements. The objective of the present study was to assess the hypothesis that abnormal gut motor activity in (preterm) newborns can be associated with underdeveloped ICCs. Specifically, the aim was to identify at which point the electrical pacemaker activity is fully developed and whether or not the development of pacemaker activity has a structural correlation with the developmental stage of ICCs. Pacemaker activity was identified as that component of the slow wave that is insensitive to L-type calcium (Ca2+) channel blockers and displays a characteristic reduction in frequency in the presence of cyclopiazonic acid (CPA), a specific inhibitor of the endoplasmic reticulum Ca2+ pump. In newborn, unfed neonates, action potentials occurred that were irregular in frequency and amplitude and sensitive to verapamil. CPA (5 microM) abolished all action potentials. Quiescent spots were observed in approximately 50% of impalements. Six hours after birth, slow-wave activity appeared at a regular frequency and amplitude, and a well-defined plateau phase was observed. Verapamil did not affect the frequency, 5 microM CPA decreased it. The effect of CPA on the pacemaker frequency 2 days after birth was identical to that observed in adult mice. In 2-hr-old neonates, ICCs could be identified through selective uptake of methylene blue, but ultrastructural features were not fully developed. At 48 hr, a complete ICC network covering Auerbach's plexus was formed, confirmed by electron microscopy. In summary, the pacemaker component of the slow waves can be identified in neonates as early as 6 hr after birth. The pacemaker component was fully developed 2 days after birth. These electrophysiological observations correlated with the development of full network characteristics of ICC-APs and the development of fully differentiated ICC-APs from "blast-like" cells.

Neural injury, repair, and adaptation in the GI tract. IV. Pathophysiology of GI motility related to interstitial cells of Cajal

Our understanding of the physiological roles played by interstitial cells of Cajal (ICC) in relation to gastrointestinal (GI) motility is still rudimentary. Nevertheless, studies into the pathophysiology of ICC are emerging at a rapid pace. Caution should be exercised, however, in assuming correlations between changes in Kit immunoreactivity, findings of ultrastructural abnormalities in ICC, and the pathophysiology and symptoms of the patients. Recent studies have revealed reduced numbers or the absence of ICC in small intestine and colon that do not exhibit normal peristaltic activity. Furthermore, important evidence is emerging that motor abnormalities in newborns may be associated with delayed maturation of the ICC network. These preliminary clinical studies provide plausible hypotheses toward the pathophysiology of certain motor disorders and strongly encourage basic scientific studies directed toward discovering the intrinsic properties of ICC as well as obtaining a deeper understanding of the physiological roles played by these cells.