Gastroparesis and functional dyspepsia: excerpts from the AGA/ANMS meeting

BACKGROUND

Despite the relatively high prevalence of gastroparesis and functional dyspepsia, the aetiology and pathophysiology of these disorders remain incompletely understood. Similarly, the diagnostic and treatment options for these two disorders are relatively limited despite recent advances in our understanding of both disorders.

PURPOSE

This manuscript reviews the advances in the understanding of the epidemiology, pathophysiology, diagnosis, and treatment of gastroparesis and functional dyspepsia as discussed at a recent conference sponsored by the American Gastroenterological Association (AGA) and the American Neurogastroenterology and Motility Society (ANMS). Particular focus is placed on discussing unmet needs and areas for future research.

NOTES and other emerging trends in gastrointestinal endoscopy and surgery: the change that we need and the change that is real

In this inaugural year of a historic presidency, gastroenterologists and gastrointestinal surgeons may well want to turn their attention to more immediate transformative events that have the potential to revolutionize their own practice in the near future. The most visible and, perhaps, controversial of these is natural orifice transluminal endoscopic surgery (NOTES), but other equally important changes are emerging as investigators around the globe vie with one another in the demonstration of increasingly audacious procedures. As is to be expected, we are also already seeing a backlash from more conservative scholars attempting to temper what they believe to be the surgical equivalent of irrational exuberance. However, by far the most common attitude among gastroenterologists toward these changes is one of indifference. In this piece, we discuss the circumstances that led to the development of NOTES and other innovative procedures, the peril that lies in ignoring them, and the true promise that they hold for our specialties.

Neural stem cell transplantation in the enteric nervous system: roadmaps and roadblocks

The enteric nervous system (ENS) is vulnerable to a variety of genetic, metabolic or environmental threats, resulting in clinical disorders characterized by loss or malfunction of neuronal elements. These disorders have been difficult to treat and there is much enthusiasm for novel therapies such as neural stem cell (NSC) transplantation to restore ENS function in diseased segments of the gut. Recent research has indicated the potential for a variety of innovative approaches to this effect using NSC obtained from the central nervous system (CNS) as well as gut derived enteric neuronal progenitors. The main goal of this review is to summarize the current status of NSC research as it applies to the ENS, delineate a roadmap for effective therapeutic strategies using NSC transplantation and point out the numerous challenges that lie ahead.

The D2/D3 agonist PD128907 (R-(+)-trans-3,4a,10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano[4,3-b]-1,4-oxazin-9-ol) inhibits stimulated pyloric relaxation and spontaneous gastric emptying

BACKGROUND

Enteric neuronal dopamine (DA) inhibits acetylcholine release and gastric motility; this has been thought to be mediated via neuronal dopamine-2 receptor (D2R). The aim of this study was to investigate the modulation of gastric motility by the dopamine-3 receptor (D3R).

METHODS

Adult Sprague-Dawley rats were used. Pyloric relaxation in response to electrical field stimulation (EFS) was assessed in an organ bath in the presence of varying concentrations of a selective D3R agonist, PD128907. Gastric emptying was assessed by the phenol red method after rats were treated with varying doses of PD128907 or DA with and without a selective D3R antagonist, L-nafadotride.

RESULTS

Immunoblotting and immunohistochemistry confirmed the presence of D3R in the myenteric neurons in the rat pylorus. D3R activation reduced EFS-induced relaxation of pyloric strips in a dose-dependent manner and significantly delayed gastric emptying compared with vehicle. The D3R antagonist partially reversed the effect of DA on gastric emptying.

CONCLUSIONS

Our data suggest a novel role for D3R in regulation of gastric motility. D3R activation delays gastric emptying, an effect that may be due to impairment of pyloric relaxation. D3R antagonists therefore hold promise as useful agents for treatment of gastric motility disorders.

Feasibility of gastric electrical stimulation by percutaneous endoscopic transgastric electrodes

BACKGROUND

Gastric electrical stimulation has been used for the treatment of drug refractory GI motility disorders and for the treatment of obesity. Both these indications have involved surgical placement of gastric electrodes, which adds to the complexity and cost of the procedure. Endoscopic placement is therefore an attractive alternative approach for this therapy.

OBJECTIVE

Our purpose was to investigate the feasibility, safety, and efficacy of percutaneous endoscopic electrodes for gastric electrical stimulation.

DESIGN AND SETTING

Experimental animal study in hound dogs.

INTERVENTIONS

Percutaneous endoscopic transgastric electrode (PETE) placement was carried out by using a pair of gastric pacing wires attached to a percutaneous endoscopic gastrostomy tube. In addition, 4 pairs of gastric serosal electrodes were implanted surgically for comparison. The efficacy of the percutaneous endoscopic electrodes was defined by their ability to entrain gastric slow waves and the induction of dysrhythmia.

RESULTS

(1) The PETE recorded gastric slow waves comparable to the serosal electrodes. (2) Gastric electrical stimulation with long pulses delivered by the PETE, at a frequency of 10% higher than the intrinsic gastric slow wave frequency, entrained gastric slow waves. (3) Gastric electrical stimulation delivered by the PETE, at a tachygastric frequency, induced gastric dysrhythmia.

LIMITATIONS

This was an animal study; however, its results are expected to be reproducible in humans, with PETE kept in place for even a longer duration than 6 to 8 weeks.

CONCLUSION

PETE placement is both feasible and safe. PETEs are effective, having a potential for use in treatment of both gastroparesis and obesity.

P2X receptor-mediated visceral hyperalgesia in a rat model of chronic visceral hypersensitivity

BACKGROUND

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder characterised by abdominal pain and bloating in association with altered bowel movements. Its pathogenesis and the underlying molecular mechanisms of visceral hyperalgesia remain elusive. Recent studies of somatic and other visceral pain models suggest a role for purinergic signalling mediated by the P2X receptor (P2XR) family.

AIMS

To examine the role of P2XR signalling in the pathogenesis in a rat model of IBS-like visceral hyperalgesia.

METHODS

Visceral hypersensitivity was induced by colonic injection of 0.5% acetic acid (AA) in 10-day-old rats and experiments were conducted at 8 weeks of age. Dorsal root ganglion (DRG) neurons innervating the colon were labelled by injection of DiI (1,1'-dioleyl-3,3,3',3-tetramethylindocarbocyanine methanesulfonate) fluorescence into the colon wall.

RESULTS

Visceral hypersensitivity was reversed by TNP-ATP (2'-(or-3')-O-(trinitrophenyl) ATP), a potent P2X1, P2X3 and P2X2/3 receptor antagonist. Rapid application of ATP (20 microM) induced a fast inactivating current in colon-specific DRG neurons from both control and AA-treated rats. There was a twofold increase in the peak ATP responses in neurons from AA-treated rats. These currents were sensitive to TNP-ATP (100 nM). Under current-clamped conditions, ATP evoked a larger membrane depolarisation in neurons from neonatal AA-treated rats than in controls. P2X3R protein expression was significantly enhanced in colon-specific DRGs 8 weeks after neonatal AA treatment.

CONCLUSIONS

These data suggest that the large enhancement of P2XR expression and function may contribute to the maintenance of visceral hypersensitivity, thus identifying a specific neurobiological target for the treatment of chronic visceral hyperalgesia.

Pain and chronic pancreatitis: is it the plumbing or the wiring?

Our progress in understanding the biology of chronic pancreatitis has been slow, particularly with respect to the pathogenesis of pain, the cardinal symptom. Although traditional theories have focused on anatomic changes, with interstitial and ductal hypertension as the main inciting factors for pain generation, subsequent studies have not confirmed a correlation between ductal pressure and the severity of pain or its relief after ductal decompression. Empirical approaches directed at anatomic causes are at best of marginal value. Although these phenomena are clearly associated with the disease, they are not likely the root cause of the pain. Instead, they probably are inciting factors on a background of neuronal sensitization induced by damage to the perineurium and subsequent exposure of the nerves to mediators and products of inflammation. In this review, we discuss the inherent limitations in our current therapies and try to identify new targets and approaches for the future, such as TRPV1, nerve growth factor-TrkA signaling, and perhaps protease activator receptor-2.

Not your father's colonoscopy: a high-tech future for screening and surveillance of colorectal cancer

The 20-year technology slump in endoscopic innovation is finally giving way to a flurry of technologies, of which many are directed specifically at improving or even replacing traditional colonoscopy. These technologies include "smart" overtubes, electronically mapped and driven instruments, and completely self-propelled devices. In addition to nonendoscopic technologies such as CT, these innovations may dramatically alter the practice of colorectal cancer screening, the "bread and butter" of gastroenterologists in this country. There are multiple and complex forces driving these changes, including a mismatch between the supply and demand in colonoscopy, patient convenience and comfort, costs, and more recently, a growing concern about the miss rate of conventional colonoscopy.

A systematic review of the efficacy of domperidone for the treatment of diabetic gastroparesis

BACKGROUND & AIMS

Despite being widely used in more than 20 countries for the treatment of diabetic gastroparesis for several decades, domperidone is approved only on an investigational basis in the United States. However, because its use is increasing, it is important for gastroenterologists in this country to understand its effectiveness in this condition. The literature on this subject varies considerably with respect to the methods and outcome measures, making a meta-analysis unfeasible.

METHODS

Our objective was to systematically analyze studies of the efficacy of domperidone in diabetic gastroparesis, with a focus on their methodologic and scientific merit. Information from 28 trials (11 full articles and 17 abstracts) from 1981 to 2007 was analyzed.

RESULTS

The average study quality score was 8.3 out of a possible 15 and the total sample size equaled 1016. Overall, 64% of the studies showed significant efficacy of domperidone on the improvement of symptoms. Sixty percent of the studies showed an efficacy in gastric emptying and 67% of the studies proved the drug effective in reducing hospital admissions.

CONCLUSIONS

Overall, our assessment is that there is level 3 evidence for the efficacy of domperidone in diabetic gastroparesis, leading to a grade C recommendation for its use in this condition. These results need to be interpreted very cautiously because of significant methodologic limitations of these studies, including the fact that most positive studies lacked a control arm. It is clear that larger and better-designed studies are needed to further validate the use of this drug in diabetic gastroparesis.

A rat model of chronic gastric sensorimotor dysfunction resulting from transient neonatal gastric irritation

BACKGROUND & AIMS

Although several pathophysiologic abnormalities have been noted in functional dyspepsia (FD), their pathogenesis is poorly understood. We hypothesized that chronic gastric hypersensitivity and gastric motor dysfunction seen in FD patients can be modeled in rats by transient gastric irritation during the neonatal period, a time of known neuronal vulnerability to long-term plasticity.

METHODS

Ten-day-old male rats received 0.2 mL 0.1% iodoacetamide (IA) in 2% sucrose daily by oral gavages for 6 days; controls received 2% sucrose. Rats in both groups were then followed to adulthood (8-10 weeks) at which point behavioral, visceromotor, and great splanchnic nerve responses to graded gastric balloon distention (GD; 20-80 mm Hg) and gastric motor function were tested.

RESULTS

IA-treated rats exhibited hypersensitivity to GD in a dose-dependent manner, as compared with the control group. The threshold of afferent nerve activation was lower and nerve responses to GD were significantly increased in IA-treated rats. Although IA-treated rats ingested food at a lower rate, gastric emptying was not significantly different between IA and control groups. However, gastric accommodation was significantly reduced in the IA group. No significant gastric pathology was seen in hypersensitive adult rats compared with controls.

CONCLUSIONS

These studies demonstrate that gastric irritation in the neonatal period can result in chronic gastric hypersensitivity and gastric motor dysfunction in adults even in the absence of significant detectable gastric pathology. Our results offer insight into the pathogenesis of chronic functional dyspepsia and provide a potential model for further study to this important clinical problem.

Distribution of interstitial cells of Cajal and nitrergic neurons in normal and diabetic human appendix

The objective of this study was to determine the distribution of enteric nerves and interstitial cells of Cajal (ICC) in the normal human appendix and in type 1 diabetes. Appendixes were collected from patients with type 1 diabetes and from non-diabetic controls. Volumes of nerves and ICC were determined using 3-D reconstruction and neuronal nitric oxide synthase (nNOS) expressing neurons were counted. Enteric ganglia were found in the myenteric plexus region and within the longitudinal muscle. ICC were found throughout the muscle layers. In diabetes, c-Kit positive ICC volumes were significantly reduced as were nNOS expressing neurons. In conclusion, we describe the distribution of ICC and enteric nerves in health and in diabetes. The data also suggest that the human appendix, a readily available source of human tissue, may be useful model for the study of motility disorders.

Inhibitors of advanced glycation end-products prevent loss of enteric neuronal nitric oxide synthase in diabetic rats

Gastrointestinal dysfunction is common in diabetes, and several studies indicate that loss of neuronal nitrergic inhibition may play an important role in its pathogenesis. However, the mechanisms responsible for this effect remain largely unknown. We have previously shown that advanced glycation end-products (AGEs) formed by non-enzymatic glycation dependent processes, can inhibit the expression of intestinal neuronal nitric oxide synthase (nNOS) in vitro acting via their receptor, receptor for AGEs. We now hypothesized that this effect may also be important in experimental diabetes in vivo. We aimed to evaluate the role of AGEs on duodenal nNOS expression and the effects of aminoguanidine (a drug that prevents AGE formation) and ALT-711 (AGE cross-link breaker) in experimental diabetes. Streptozotocin induced diabetic rats were randomized to no treatment, treatment with aminoguanidine (1 g L(-1) daily through drinking water) at the induction of diabetes, or treatment with ALT-711 (3 mg kg(-1) intraperitoneally), beginning at week 6. A fourth group was used as healthy controls. We performed real time polymerase chain reaction, Western blotting and immunohistochemistry to detect nNOS expression. AGE levels were analysed using sandwich ELISA. Diabetes enhanced accumulation of AGEs in serum, an effect that was prevented by treatment with aminoguanidine and ALT-711. Further, diabetic rats showed a significant reduction in duodenal nNOS expression by mRNA, protein and immunocytochemistry, an effect that was prevented by aminoguanidine. ALT-711 had similar effects on nNOS protein and immunohistochemistry (but not on mRNA levels). The generation of AGEs in diabetes results in loss of intestinal nNOS expression and may be responsible for enteric dysfunction in this condition. This study suggests that treatment directed against AGEs may be useful for the treatment of gastrointestinal complications of diabetes.

Preliminary pneumoperitoneum facilitates transgastric access into the peritoneal cavity for natural orifice transluminal endoscopic surgery: a pilot study in a live porcine model

BACKGROUND AND STUDY AIMS

Safe entrance into the peritoneal cavity through the gastric wall is paramount for the successful clinical introduction of natural orifice transluminal endoscopic surgery (NOTES). The aim of the study was to develop alternative safe transgastric access to the peritoneal cavity.

PATIENTS AND METHODS

We performed 11 survival experiments on 50-kg pigs. In sterile conditions, the abdominal wall was punctured with a Veress needle. The peritoneal cavity was insufflated with 2 L carbon dioxide (CO (2)). A sterile endoscope was introduced into the stomach through a sterile overtube; the gastric wall was punctured with a needle-knife; after balloon dilation of the puncture site, the endoscope was advanced into the peritoneal cavity. Peritoneoscopy with biopsies from abdominal wall, liver and omentum, was performed. The endoscope was withdrawn into the stomach. The animals were kept alive for 2 weeks and repeat endoscopy was followed by necropsy.

RESULTS

The pneumoperitoneum, easily created with the Veress needle, lifted the abdominal wall and made a CO (2)-filled space between the stomach and adjacent organs, facilitating gastric wall puncture and advancement of the endoscope into the peritoneal cavity. There were no hemodynamic changes or immediate or delayed complications related to pneumoperitoneum, transgastric access, or intraperitoneal manipulations. Follow-up endoscopy and necropsy revealed no problems or complications inside the stomach or peritoneal cavity.

CONCLUSIONS

Creation of a preliminary pneumoperitoneum with a Veress needle facilitates gastric wall puncture and entrance into the peritoneal cavity without injury to adjacent organs, and can improve the safety of NOTES.

Transient receptor potential vanilloid 1 mediates hyperalgesia and is up-regulated in rats with chronic pancreatitis

BACKGROUND & AIMS

The neurobiologic basis of pancreatic hyperalgesia in chronic pancreatitis (CP) is understood poorly and there is a need to identify novel therapeutic targets. Our aim was to study the role of the transient receptor potential vanilloid 1 (TRPV1), a key integrator of noxious stimuli, in the pathogenesis of pancreatic pain in a rat model of CP.

METHODS

CP was induced in rats by intraductal injection of trinitrobenzene sulfonic acid. TRPV1 currents in pancreas-specific DRG neurons were measured using perforated patch-clamp techniques. Reverse-transcription polymerase chain reaction was used to measure mRNA expression of TRPV1 in these neurons after laser capture microdissection. Immunofluorescence and Western blot analysis, using TRPV1-specific antibodies, also were performed. Pancreatic hyperalgesia was assessed by rat's nocifensive behavior to electrical stimulation of the pancreas.

RESULTS

CP was associated with a 4-fold increase in capsaicin-induced current density (P < .02), along with an increase in the proportion of pancreas-specific DRG neurons that responded to capsaicin (52.9% in controls vs 79.0% in CP; P < .05). CP also was associated with a significant increase in TRPV1 expression both at the messenger RNA and protein level in whole thoracic DRGs and pancreas-specific sensory neurons. Systemic administration of the TRPV1 antagonist SB-366791 markedly reduced both visceral pain behavior and referred somatic hyperalgesia in rats with CP, but not in control animals.

CONCLUSIONS

TRPV1 up-regulation and sensitization is a specific molecular mechanism contributing to hyperalgesia in CP and represents a useful target for treating pancreatic hyperalgesia caused by inflammation.

A new stapler-based full-thickness transgastric access closure: results from an animal pilot trial

BACKGROUND AND STUDY AIMS

Reliable closure of the transluminal incision is the crucial step for natural orifice transluminal endoscopic surgery (NOTES) procedures. The aim of this study was to evaluate the feasibility and effectiveness of transgastric access closure with a flexible stapling device in a porcine survival model.

PATIENTS AND METHODS

We carried out four experiments (two sterile and two nonsterile) on 50 kg pigs. The endoscope was passed through a gastrotomy made with a needle knife and an 18-mm controlled radial expansion dilating balloon. After peritoneoscopy, a flexible linear stapling device (NOLC60, Power Medical Interventions, Langhorne, Pennsylvania, USA) was perorally advanced over a guide wire into the stomach, positioned under endoscopic guidance, and opened to include the site of gastrotomy between its two arms; four rows of staples were fired. One animal was sacrificed 24 hours after the procedure (progression of pre-existing pneumonia). The remaining animals were survived for 1 week and then underwent repeat endoscopy and postmortem examination.

RESULTS

Peroral delivery and positioning of the stapling device involved some technical difficulties, mostly due to the short length (60 cm) of the stapling device. The stapler provided complete leak-resistant gastric closure in all pigs. None of the surviving animals had any clinical signs of infection. Necropsy demonstrated an intact staple line with full-thickness healing of the gastrotomy in all animals. Histologic examination confirmed healing, but also revealed intramural micro-abscesses within the gastric wall after nonsterile procedure.

CONCLUSIONS

Gastrotomy closure with a perorally delivered flexible stapling device created a leak-resistant transmural line of staples followed by full-thickness healing of the gastric wall incision. Increasing the length of the instrument and adding device articulation will further facilitate its use for NOTES procedures.

Submucosal endoscopic esophageal myotomy: a novel experimental approach for the treatment of achalasia

BACKGROUND AND STUDY AIMS

The most permanent method of treating achalasia is a surgical myotomy. Because of the requirement for a mucosal incision and the risk of perforation, this procedure has not generally been approached endoscopically. We hypothesized that we could perform a safe and robust myotomy by working in the submucosal space, accessed from the esophageal lumen.

MATERIALS AND METHODS

Four pigs were used for this experiment. Baseline lower esophageal sphincter (LES) pressures were recorded and the pigs underwent upper endoscopy using a standard endoscope. A submucosal saline lift was created approximately 5 cm above the LES and a small nick was made in the mucosa in order to facilitate the introduction of a dilating balloon. After dilation, the scope was introduced over the balloon into the submucosal space and advanced toward the now visible fibers of the LES. The circular layer of muscle was then cleanly incised using an electrocautery knife in a distal-to-proximal fashion, without complications. The scope was then withdrawn back into the lumen and the mucosal defect was closed with endoscopically applied clips. The entire procedure took less than 15 minutes. Manometry was repeated on day 5 after the procedure and the animals were euthanized on day 7.

RESULTS

LES pressures fell significantly from an average of 16.4 mm Hg to an average of 6.7 mm Hg after the myotomy. The necropsy examinations revealed no evidence of mediastinitis or peritonitis.

CONCLUSIONS

Endoscopic submucosal esophageal myotomy is feasible, safe, and effective in the short term. It has the potential for being useful in patients with achalasia. The submucosal space is a novel and potentially important field of operation for endoscopic procedures.

Submucosal endoscopic esophageal myotomy: a novel experimental approach for the treatment of achalasia

BACKGROUND AND STUDY AIMS

The most permanent method of treating achalasia is a surgical myotomy. Because of the requirement for a mucosal incision and the risk of perforation, this procedure has not generally been approached endoscopically. We hypothesized that we could perform a safe and robust myotomy by working in the submucosal space, accessed from the esophageal lumen.

MATERIALS AND METHODS

Four pigs were used for this experiment. Baseline lower esophageal sphincter (LES) pressures were recorded and the pigs underwent upper endoscopy using a standard endoscope. A submucosal saline lift was created approximately 5 cm above the LES and a small nick was made in the mucosa in order to facilitate the introduction of a dilating balloon. After dilation, the scope was introduced over the balloon into the submucosal space and advanced toward the now visible fibers of the LES. The circular layer of muscle was then cleanly incised using an electrocautery knife in a distal-to-proximal fashion, without complications. The scope was then withdrawn back into the lumen and the mucosal defect was closed with endoscopically applied clips. The entire procedure took less than 15 minutes. Manometry was repeated on day 5 after the procedure and the animals were euthanized on day 7.

RESULTS

LES pressures fell significantly from an average of 16.4 mm Hg to an average of 6.7 mm Hg after the myotomy. The necropsy examinations revealed no evidence of mediastinitis or peritonitis.

CONCLUSIONS

Endoscopic submucosal esophageal myotomy is feasible, safe, and effective in the short term. It has the potential for being useful in patients with achalasia. The submucosal space is a novel and potentially important field of operation for endoscopic procedures.

NOTES: a gastroenterologist's perspective

Once in a few decades in science or medicine, an idea emerges that is so powerful that it changes forever how we think about the field. Such is the case of natural orifice transluminal endoscopic surgery (NOTES). NOTES has yet to prove its value in patients. However, having challenged one of the most fundamental and deeply entrenched dogmas in surgery and endoscopy, many of us feel that "we will never be the same again." In this article I will discuss the implications of this paradigm shift and suggest strategies for both gastroenterologists and surgeons that will allow us to test its full potential.

Neural stem cells for the treatment of disorders of the enteric nervous system: strategies and challenges

The main goal of this review is to summarize the status of the research in the field of stem cells transplantation, as it is applicable to the treatment of gastrointestinal motility. This field of research has advanced tremendously in the past 10 years, and recent data produced in our laboratories as well as others is contributing to the excitement on the use of neural stem cells (NSC) as a valuable therapeutic approach for disorders of the enteric nervous system characterized by a loss of critical neuronal subpopulations. There are several sources of NSC, and here we describe therapeutic strategies for NSC transplantation in the gut. These include using NSC as a relatively nonspecific cellular replacement strategy in conditions where large populations of neurons or their subsets are missing or destroyed. As with many other recent "breakthroughs" stem cell therapy may eventually prove to be overrated. However, at the present time, it does appear to provide the hope for a true cure for many currently intractable diseases of both the central and the peripheral nervous system. Certainly more extensive research is needed in this field. We hope that our review will encourage new investigators in entering this field of research ad contribute to our knowledge of the potentials of NSC and other cells for the treatment of gastrointestinal dysmotility.

Peroral transgastric endoscopic primary repair of a ventral hernia in a porcine model

BACKGROUND AND STUDY AIMS

Multiple studies have demonstrated the feasibility of peroral transgastric endoscopic procedures in animal models. The aim of the study was to evaluate the feasibility of a peroral transgastric endoscopic approach to repair abdominal wall hernias.

PATIENTS AND METHODS

We performed acute experiments under general anesthesia with endotracheal intubation using 50-kg pigs. Following peroral intubation an incision of the gastric wall was made and the endoscope was advanced into the peritoneal cavity. An internal anterior abdominal wall incision was performed with a needle knife to create an animal model of a ventral hernia. After hernia creation an endoscopic suturing device was used for primary repair of the hernia. After completion of the hernia repair the endoscope was withdrawn into the stomach and the gastric wall incision was closed with endoscopic clips. Then the animals were killed for necropsy.

RESULTS

Two acute experiments were performed. Incision of the gastric wall was easily achieved with a needle knife and a pull-type sphincterotome. A large (3 x 2 cm) defect of the abdominal wall (ventral hernia model) was closed with five or six sutures using the endoscopic suturing device. Postmortem examination revealed complete closure of the hernia without any complications.

CONCLUSIONS

Transgastric endoscopic primary repair of ventral hernias in a porcine model is feasible and may be technically simpler than laparoscopic surgery.

Diabetes induces sex-dependent changes in neuronal nitric oxide synthase dimerization and function in the rat gastric antrum

Diabetic gastroparesis is a disorder that predominantly affects women. However, the biological basis of this sex bias remains completely unknown. In this study we tested the hypothesis that a component of this effect may be mediated by the nitrergic inhibitory system of the enteric nervous system. Age-matched male and female Sprague-Dawley rats were studied 8 or 12 wk after streptozotocin (55 mg/kg body wt ip)-induced sustained hyperglycemia and compared with controls. Solid gastric emptying (GE) studies were performed in all the groups. Changes in gastric antrum neuronal nitric oxide synthase (nNOS) mRNA and protein levels were analyzed by real-time PCR and Western immunoblotting, respectively. nNOS dimerization studies were performed using low-temperature SDS-PAGE. In vitro nitrergic relaxation (area under curve/mg tissue wt) was studied after the application of electric field stimulation in an organ bath. Changes in intragastric pressure (mmHg.s) in freely moving rats in the presence or absence of N(G)-nitro-l-arginine methyl ester (nitric oxide synthase inhibitor) were examined by an ambulatory telemetric method. After diabetes induction, GE is delayed in both male and female rats. However, diabetic females exhibited significant delayed GE than in diabetic males. Compared with male controls, gastric nNOS expression and nitrergic relaxation were substantially elevated in healthy female control rats, accompanied by significantly reduced intragastric pressure. The active dimeric form and dimer-to-monomer ratio of nNOSalpha were also higher in healthy females compared with male rats (P < 0.05). Diabetic females, but not males, showed significant (P < 0.05) impairment in both gastric nNOSalpha dimerization and nitrergic relaxation, accompanied by an increase in intragastric pressure. Our data provide evidence that females may have a greater dependency on the nitrergic mechanisms in health. Furthermore, diabetes seems to affect the nitrergic system to a greater extent in females than in males. Together, these changes may account for the greater vulnerability of females to diabetic gastric dysfunction.

Going for the loop: a unique overtube for the difficult colonoscopy

In up to 10% to 20% of colonoscopies, complete intubation of the colon may be considerably difficult. A principal cause of difficulty is looping of the endoscope shaft in a floppy, often tortuous segment of the colon that typically happens in the sigmoid colon. Also, if looping is not recognized and the scope is advanced with abandon, the risk of perforation will rise. Special "variable stiffness" colonoscopies are expensive and have not been unequivocally shown to be useful in preventing looping. The simplest approach to prevent looping is perhaps the use of an over-tube to prevent the shaft from bowing out. The ShapeLock could offer an ideal over-tube that is flexible enough to safely and easily negotiate bends in the colon but when needed be rigid enough to prevent looping with just a snap of its handle. It also has potential other applications including enteroscopy, transgastric endoscopy and access to difficult regions of the upper gastrointestinal tract.

The vanilloid receptor initiates and maintains colonic hypersensitivity induced by neonatal colon irritation in rats

BACKGROUND & AIMS

Robust chemical or mechanical irritation of the colon of neonatal rats leads to chronic visceral hypersensitivity. The clinical and physiologic relevance of such noxious stimulation in the context of human irritable bowel syndrome is questionable. The aims of this study were to determine whether mild chemical irritation of the colon of neonatal rats produced persistent changes in visceral sensitivity and to evaluate the role of transient receptor potential vanilloid 1 (TRPV1) in the initiation and maintenance of visceral hypersensitivity.

METHODS

Ten-day-old rat pups received an intracolonic infusion of 0.5% acetic acid in saline. TRPV1 inhibitors were administered 30 minutes before acetic acid sensitization. Sensitivity of the colon to balloon distention (CRD) in adults was measured by grading their abdominal withdrawal reflex and electromyographic responses. In adult rats, TRPV1 antagonist was injected intraperitoneally 30 minutes before CRD.

RESULTS

Neonatal acetic acid treatment resulted in higher sensitivity to CRD in adult rats compared with controls in the absence of histopathologic signs of inflammation. Treatment of colons of adult rats with acetic acid did not produce persistent sensitization. Antagonism of the TRPV1 before neonatal administration of acetic acid and after established visceral hypersensitivity attenuated sensitivity to CRD. TRPV1 expression was increased in dorsal root ganglia-containing colon afferent neurons.

CONCLUSIONS

We have described a new model for persistent colonic sensory dysfunction following a transient noxious stimulus in the neonatal period and a potentially important role for TRPV1 in initiation and maintenance of persistent visceral hypersensitivity.

Enhanced excitability and suppression of A-type K+ current of pancreas-specific afferent neurons in a rat model of chronic pancreatitis

Chronic pancreatitis (CP) is a relatively common disorder, characterized by glandular insufficiency and chronic, often intractable, pain. The mechanism of pain in CP is poorly understood. We have previously developed a model of trinitrobenzene sulphonic acid (TNBS)-induced CP that results in nociceptive sensitization in rats. This study was designed to examine changes in the excitability and alteration of voltage-gated K(+) currents of dorsal root ganglia (DRG) neurons innervating the pancreas. CP was induced in adult rats by an intraductal injection of TNBS. DRG neurons innervating the pancreas were identified by 1,1'-dioleyl-3,3,3',3-tetramethylindocarbocyanine methanesulfonate fluorescence labeling. Perforated patch-clamp recordings were made from acutely dissociated DRG neurons from control and TNBS-treated rats. Pancreas-specific DRG neurons displayed more depolarized resting potentials in TNBS-treated rats than those in controls (P < 0.02). Some neurons from the TNBS-treated group exhibited spontaneous firings. TNBS-induced CP also resulted in a dramatic reduction in rheobase (P < 0.05) and a significant increase in the number of action potentials evoked at twice rheobase (P < 0.05). Under voltage-clamp conditions, neurons from both groups exhibited transient A-type (I(A)) and sustained outward rectifier K(+) currents (I(K)). Compared with controls, the average I(A) but not the average I(K) density was significantly reduced in the TNBS-treated group (P < 0.05). The steady-state inactivation curve for I(A) was displaced by approximately 20 mV to more hyperpolarized levels after the TNBS treatment. These data suggest that TNBS treatment increases the excitability of pancreas-specific DRG neurons by suppressing I(A) density, thus identifying for the first time a specific molecular mechanism underlying chronic visceral pain and sensitization in CP.

Immediate endoscopic closure of colon perforation by using a prototype endoscopic suturing device: feasibility and outcome in a porcine model (with video)

BACKGROUND

Perforation is an uncommon but potentially devastating complication of colonoscopy. Surgical closure is the standard of care. Immediate endoluminal closure of a perforation would avoid the morbidity and mortality associated with general anesthesia, laparotomy, and surgical repair.

OBJECTIVES

To evaluate the feasibility and safety of full-thickness endoscopic closure of colonic perforations with a prototype endoscopic suturing device, the Eagle Claw, in a porcine model.

DESIGN

Endoscopic animal experimental study of closure of colon perforation by using a porcine model.

SUBJECTS

Ten pigs were included in the study.

INTERVENTIONS

The Eagle Claw was used to close small perforations (1.5 to 2 cm) of the colon created by needle-knife with the animal under general anesthesia by using the endoluminal route. All animals received intravenous antibiotics and were allowed to eat after 24 hours.

MAIN OUTCOME MEASUREMENTS

The animals were monitored daily for signs of sepsis and peritonitis. On day 7, they were euthanized. The peritoneal cavity was examined for fecal peritonitis, and the colon perforation site was checked for wound dehiscence and pericolic abscess formation.

RESULTS

Endoscopic closure of the colon perforation was successful in 7 animals, and they recovered well without any sepsis or peritonitis. Necropsy did not reveal fecal peritonitis or pericolonic abscess formation at the site of perforation, and the perforation healed well. Closure was successful in 1 animal, but necropsy revealed dehiscence of the colon perforation site. Endoscopic closure was unsuccessful in 2 animals, and these were euthanized immediately.

CONCLUSIONS

Closure of acute perforation of the colon is feasible with the Eagle Claw endoscopic suturing device in a porcine model.

Muscarinic receptors: their distribution and function in body systems, and the implications for treating overactive bladder

1. The effectiveness of antimuscarinic agents in the treatment of the overactive bladder (OAB) syndrome is thought to arise through blockade of bladder muscarinic receptors located on detrusor smooth muscle cells, as well as on nondetrusor structures. 2. Muscarinic M3 receptors are primarily responsible for detrusor contraction. Limited evidence exists to suggest that M2 receptors may have a role in mediating indirect contractions and/or inhibition of detrusor relaxation. In addition, there is evidence that muscarinic receptors located in the urothelium/suburothelium and on afferent nerves may contribute to the pathophysiology of OAB. Blockade of these receptors may also contribute to the clinical efficacy of antimuscarinic agents. 3. Although the role of muscarinic receptors in the bladder, other than M3 receptors, remains unclear, their role in other body systems is becoming increasingly well established, with emerging evidence supporting a wide range of diverse functions. Blockade of these functions by muscarinic receptor antagonists can lead to similarly diverse adverse effects associated with antimuscarinic treatment, with the range of effects observed varying according to the different receptor subtypes affected. 4. This review explores the evolving understanding of muscarinic receptor functions throughout the body, with particular focus on the bladder, gastrointestinal tract, eye, heart, brain and salivary glands, and the implications for drugs used to treat OAB. The key factors that might determine the ideal antimuscarinic drug for treatment of OAB are also discussed. Further research is needed to show whether the M3 selective receptor antagonists have any advantage over less selective drugs, in leading to fewer adverse events.

Suppression of nNOS expression in rat enteric neurones by the receptor for advanced glycation end-products

Diabetes mellitus results in a loss of neuronal nitric oxide synthase (nNOS) expression in the myenteric plexus but the underlying mechanisms remain unknown. We hypothesized that this may be mediated by advanced glycation end-products (AGEs), a class of modified protein adducts formed by non-enzymatic glycation that interact with the receptor for AGE (RAGE) and which are important in the pathogenesis of other diabetic complications. Whole mount preparations of longitudinal muscles with adherent myenteric plexus (LM-MPs) from the duodenum of adult male rats were exposed to glycated bovines serum albumin (AGE-BSA) or BSA for 24 h. Western blotting, immunohistochemistry and real-time reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA showed a significant reduction in nNOS expression in LM-MPs after exposure to AGE-BSA. NO release, as measured by the Griess reaction, was also significantly reduced by AGE-BSA. A neutralizing antibody against RAGE attenuated the reduction of nNOS protein caused by AGE-BSA. Immunohistochemistry revealed co-localization of RAGE expression with Hu, a marker for neuronal cells but not for S-100, a glial marker. Advanced glycation end-products reduce nNOS expression in the rat myenteric neurones acting via the receptor RAGE. Our results suggest novel pathways for disruption of the nitrergic phenotype in diabetes.

Treatment of gastroparesis: a multidisciplinary clinical review

This clinical review on the treatment of patients with gastroparesis is a consensus document developed by the American Motility Society Task Force on Gastroparesis. It is a multidisciplinary effort with input from gastroenterologists and other specialists who are involved in the care of patients with gastroparesis. To provide practical guidelines for treatment, this document covers results of published research studies in the literature and areas developed by consensus agreement where clinical research trials remain lacking in the field of gastroparesis.

Effect of a novel pancreatic stent design on short-term pancreatic injury in a canine model

BACKGROUND AND STUDY AIMS

Attempts to address the problem of injury to the pancreas by indwelling pancreatic stents are limited by our lack of knowledge of the pathogenesis of stent-induced injury and its relationship to stent morphology and the duration of stenting. The aim of our study was to evaluate pancreatic injury induced by 1 week of stenting with a 5F indwelling pancreatic stent of novel design, the "wing stent."

METHODS

Pancreatic stents (5F) were placed surgically in eight dogs; wing stents (WS-5F) were used in four dogs and conventional stents (CS-5F) in another four. Two dogs underwent duodenotomy without stent placement (controls). The pancreas was harvested for microscopy at 1 week. A pathologist who was unaware of the source of the specimens graded the pancreatic injury.

RESULTS

Although pancreatic injury was observed in both the CS-5F and WS-5F groups after 1 week of indwelling pancreatic stenting, it was considerably less severe in the WS-5F group compared with the CS-5F group (1.01 +/- 0.10 vs. 1.63 +/- 0.14, P < 0.01). All components of pancreatic injury were affected, with the most dramatic differences noted in inflammation, fibrosis, and edema. The differences were most marked in the stented segment ( P < 0.001) and in the upstream segment of the pancreas ( P < 0.05).

CONCLUSIONS

Indwelling conventional pancreatic stents can cause significant pancreatic injury even when left in place for only 1 week. A wing design can significantly ameliorate stent-induced changes.

Biliary drainage by using stents without a central lumen: a pilot study

BACKGROUND

Despite several attempts to make the conventional tubular stents with a central lumen for flow less susceptible to a biofilm buildup and thereby prevent clogging, this goal has remained elusive. We hypothesized that the creation of pathways for fluid flow around the stent instead of through it would avoid this problem. The aim of our study was to report the development and the evaluation of a novel lumen-less stent.

METHODS

By using a software computer modeling, a 10F "winged" stent was designed. A pilot feasibility study was performed by using a prototype of this stent for endoscopic biliary drainage in 5 patients with malignant biliary obstruction.

OBSERVATIONS

Modeling data revealed that the winged stent offers a larger surface area for flow, higher velocity of flow, and increased flow rates compared with the conventional tubular stent. In the clinical trial, there was a significant decrease of serum bilirubin after the placement of this stent (serum bilirubin before and 2 weeks after stent placement, 14.94 +/- 5.7 mg/dL vs. 2.86 +/- 1.4 [p < 0.004]), accompanied by radiologic evidence of decompression of the biliary system.

CONCLUSIONS

We have shown that it is possible to provide adequate biliary drainage by using a stent without a lumen. Such a design may have potential clinical advantages over existing designs.

Transgastric endoscopic splenectomy: is it possible?

BACKGROUND

We have previously reported the feasibility of diagnostic and therapeutic peritoneoscopy including liver biopsy, gastrojejunostomy, and tubal ligation by an oral transgastric approach. We present results of per-oral transgastric splenectomy in a porcine model. The goal of this study was to determine the technical feasibility of per-oral transgastric splenectomy using a flexible endoscope.

METHODS

We performed acute experiments on 50-kg pigs. All animals were fed liquids for 3 days prior to procedure. The procedures were performed under general anesthesia with endotracheal intubation. The flexible endoscope was passed per orally into the stomach and puncture of the gastric wall was performed with a needle knife. The puncture was extended to create a 1.5-cm incision using a pull-type sphincterotome, and a double-channel endoscope was advanced into the peritoneal cavity. The peritoneal cavity was insufflated with air through the endoscope. The spleen was visualized. The splenic vessels were ligated with endoscopic loops and clips, and then mesentery was dissected using electrocautery.

RESULTS

Endoscopic splenectomy was performed on six pigs. There were no complications during gastric incision and entrance into the peritoneal cavity. Visualization of the spleen and other intraperitoneal organs was very good. Ligation of the splenic vessels and mobilization of the spleen were achieved using commercially available devices and endoscopic accessories.

CONCLUSIONS

Transgastric endoscopic splenectomy in a porcine model appears technically feasible. Additional long-term survival experiments are planned.

Molecular and behavioral changes in nociception in a novel rat model of chronic pancreatitis for the study of pain

The approach to the management of painful chronic pancreatitis has been empirical, primarily due to the lack of information about biological mechanisms producing pain. To facilitate research into pain mechanisms, our aim was to assess a rat model of chronic pancreatitis induced by pancreatic infusion of trinitrobenzene sulfonic acid as a model of painful pancreatitis. Nociception was assessed by measuring mechanical sensitivity of the abdomen and by recording the number of nocifensive behaviors in response to electrical stimulation of the pancreas. Expression of neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP) in the thoracic dorsal root ganglia receiving input from the pancreas and nerve growth factor (NGF) in the pancreas were measured. Rats with pancreatitis exhibited marked increase in sensitivity to mechanical probing of the abdomen and increased sensitivity to noxious electrical stimulation of the pancreas. There were significant increases in NGF protein in the pancreas and in expression of neuropeptides CGRP and SP in the sensory neurons from dorsal root ganglia receiving input from the pancreas. We have established quantitative measures of referred nociception and pancreatic hyperalgesia in a rat model of chronic pancreatitis that bears histological similarities to the human disease. This model has considerable construct, face and predictive validity for the human condition. It is of importance for the study of the pathogenesis of pain in this condition and can facilitate the development of new therapeutic options.

Neural stem cell transplantation in the stomach rescues gastric function in neuronal nitric oxide synthase-deficient mice

BACKGROUND & AIMS

Nitric oxide is a major inhibitory neurotransmitter in the enteric nervous system. Loss or dysfunction of nitrinergic neurons is associated with serious disruptions of motility, intractable symptoms, and long-term suffering. The aim of this study was to evaluate the effect of intrapyloric transplantation of neural stem cells (NSCs) on gastric emptying and pyloric function in nNOS-/- mice, a well-established genetic model of gastroparesis.

METHODS

NSCs were isolated from embryonic mice transgenically engineered to express green fluorescent protein and transplanted into the pylorus of nNOS-/- mice. Grafted cells were visualized in pyloric sections and further characterized by immunofluorescence staining. One week posttransplantation, gastric emptying to a non-nutrient meal was measured using the phenol red method and pyloric function was assessed by measuring the relaxation of pyloric strips in an organ bath in response to electrical field stimulation (EFS) under nonadrenergic, noncholinergic conditions.

RESULTS

One week following implantation, grafted NSCs differentiated into neurons and expressed neuronal nitric oxide synthase. Gastric emptying was significantly increased in mice that received NSCs as compared with vehicle-injected controls (49.67% vs 35.09%; P < .01 by Student t test). EFS-induced relaxation of pyloric strips was also significantly increased (P < .01 by 2-way analysis of variance). The nitric oxide synthase inhibitor N(G)-nitro-l-arginine methyl ester and the neuronal blocker tetrodotoxin blocked the EFS-induced relaxation, indicating that the observed effect is NO mediated and neuronally derived.

CONCLUSIONS

Our results support the potential of NSC transplantation as a viable therapeutic option for neuroenteric disorders.

Developing an animal model of massive ulcer bleeding for assessing endoscopic hemostatic devices

BACKGROUND

Existing animal models of ulcerative bleeding are not suitable for endoscopic investigation. We describe a new porcine model of massive arterial bleeding in the stomach and its use for assessing a novel endoscopic suturing device.

METHODS

Two animal models were investigated. In model 1, the short gastric artery (mean diameter 2 mm) was divided near its gastric end. A mucosal defect was created near the greater curve and the divided artery was brought into the lumen of the stomach through a submucosal tunnel. An inflatable plastic cuff was placed around the base of the artery. Cuff deflation led to massive bleeding. In model 2, the short gastric artery was carefully exposed along a segment of 2 cm on the side facing the stomach. It was then anchored to a small gastrostomy made at the posterior wall near the vessel. At endoscopy an ulcer-like lesion could be seen with a pulsatile vessel at the base and brisk bleeding could be started by cutting a hole in the artery using endoscissors. The pigs were heparinized by an intravenous bolus of 110-300 units per kilogram, in both models. A prototype suturing device, the Eagle Claw, was inserted using a gastroscope and the curved needle was driven around the bleeding artery. Extracorporeal knotting or intracorporeal ligation was done endoscopically.

RESULTS

Pulsatile arterial bleeding was successfully created in four pigs using model 1, and in another four pigs using model 2. Model 2 was more reproducible and less time-consuming to create. Endoscopic suturing controlled arterial bleeding in five out of eight pigs with a single stitch and in another three pigs with an additional stitch.

CONCLUSION

This animal model provides reproducible massive hemorrhage suitable for endoscopic studies. Control of gastric bleeding from large arteries by endoscopic suturing is possible.

Caspase inhibition increases survival of neural stem cells in the gastrointestinal tract

Neural stem cell (NSC) transplantation is a promising tool for the restoration of the enteric nervous system in a variety of motility disorders. Post-transplant survival represents a critical limiting factor for successful repopulation. The aim of this study was to determine the role of both immunological as well as non-immune-mediated mechanisms on post-transplant survival of NSC in the gut. Mouse CNS-derived NSC (CNS-NSC) were transplanted into the pylorus of recipient mice with and without the addition of a caspase-1 inhibitor (Ac-YVAD-cmk) in the injection media. In a separate experiment, CNS-NSC were transplanted in the pylorus of mice that were immunosuppressed by administration of cyclosporin A (CsA). Apoptosis and proliferation of the implanted cells was assessed 1 and 7 days post-transplantation. Survival was assessed 1 week post-transplantation. The degree of immunoresponse was also measured. The addition of a caspase-1 inhibitor significantly reduced apoptosis, increased proliferation and enhanced survival of CNS-NSC. CsA-treatment did not result in improved survival. Our results indicate that caspase-1 inhibition, but not immunosuppression, improves survival of CNS-NSC in the gut. Pre-treatment with a caspase-1 inhibitor may be a practical method to enhance the ability of transplanted CNS-NSC to survive in their new environment.

Graded esophageal mucosal ablation with cryotherapy, and the protective effects of submucosal saline

BACKGROUND AND STUDY AIMS

Knowledge about the extent of damage with endoscopic cryotherapy is of critical importance before its potential as an ablative therapy is explored. The aims of this study were to evaluate the extent of transmural esophageal necrosis at 48 hours after cryospraying for varying durations, using a novel device based on the Joule-Thomson effect and with carbon dioxide as the refrigerant gas, and to examine the role of submucosal injection of saline in preventing deeper injury.

METHODS

Cryospray was applied to several different segments of the esophagus for various lengths of time (15, 30, 45, 60, and 120 seconds) in a pig model. In another set of experiments performed subsequently, 2 ml of saline was injected into the submucosa and cryospray was applied for 60 seconds.

RESULTS

Esophageal cryotherapy resulted in a dose-dependent injury to the esophagus: esophageal necrosis was minimal or limited to the mucosa after 15 seconds of cryospraying, extended to involve the submucosa after 30 seconds of cryospraying, and involved the muscularis propria also after 45 seconds, with frank transmural necrosis found after 120 seconds of cryotherapy. Prior submucosal saline injection protected against muscular necrosis from prolonged cryotherapy.

CONCLUSIONS

We have shown a dose-dependent effect of cryotherapy on esophageal mucosal ablation. When more extensive lesions are encountered, it may be advisable to consider using submucosal saline injections as an additional safeguard against deeper injury.

Assessing the adequacy of endoscopically tied knots: a functional approach

BACKGROUND AND STUDY AIMS

Endoscopic intracorporeal knots have potentially enormous applications in endoscopic surgery. We describe a method for testing the security of various types of endoscopically tied knots using a vessel perfusion manometer system.

METHODS

A 4-cm segment of porcine splenic artery was placed on the mucosal surface of a pig stomach. The two ends of the vessel were brought out through the gastric wall and connected to a two-way manometer. One end was also joined to a pressure infusion bag. The stomach was mounted in an Erlangen training model. A long 3/0 nylon thread, previously introduced into the submucosal layer of the stomach and encircling the vessel, was brought out from the mouth. Three-throw square knots, Mayo knots, "surgeon's" knots and five-throw square knots were tied and pushed into place using a cap attached to a gastroscope. The pressure at the two ends of the artery was compared. If the pressure could be increased to over 200 mm Hg at one end without a change in the other, the knot was considered secure.

RESULTS

Each type of knot was tested 12 times under endoscopic vision. The range for mean knotting time was 3.4 - 4.5 minutes. Five-throw knots took significantly longer to tie than three-throw knots (P < 0.005). There was one loose knot in each of the three-throw and Mayo groups, and three each in the "surgeon's" and five-throw groups (P > 0.05).

CONCLUSIONS

This system is a reliable model for testing intracorporeal knots tied endoscopically. A three-half-hitches square knot with 3/0 nylon, tied using a flexible endoscope and knot-tightening cap, can withstand pressure up to 200 mm Hg.

Transoral obesity surgery: endoluminal gastroplasty with an endoscopic suture device

BACKGROUND AND STUDY AIMS

Surgical creation of a small gastric pouch with a restricted outlet is a well-established option for the treatment of morbid obesity. This report describes initial experience with endoscopic transoral stomach partition using a newly designed suturing apparatus.

MATERIALS AND METHODS

A fresh porcine stomach was placed in the Erlangen model. A prototype suture device, incorporating a curved needle and an intracorporeal tightening mechanism, was used in this procedure. A long fishing line was first introduced into the stomach, with the two ends left outside. The suturing device, premounted outside a standard gastroscope, was inserted into the stomach and delivered several stitches attaching the fishing line to both the anterior and posterior walls along the line for the stomach to be partitioned. Five throws of half-hitches were tied onto the fishing line extracorporeally and separately pushed into place, creating a gastric pouch just below the esophagogastric junction. A flexible sheath of 8 cm long was then put on one side of the fishing line and pushed into the stomach. Additional extracorporeal knots were tied on the fishing line, forming a restrictive ring at the outlet of the pouch. The ring was then anchored to the stomach wall with similar endosutures.

RESULTS

The proximal gastric pouch, with an estimated volume of approximately 100 ml, was successfully created with a restrictive band at its outlet. All of the stitches were securely sutured, with consistent penetration of the muscular layer of the stomach wall.

CONCLUSIONS

In a bench model, it is technically possible to accomplish transoral gastroplasty endoscopically with an intraluminal suturing device. Further live animal studies will be needed in order to confirm the efficacy and safety of this procedure before clinical application.

Enteric neural crest-derived cells and neural stem cells: biology and therapeutic potential

The enteric nervous system arises from two regions of the neural crest; the vagal neural crest which gives rise to the vast majority of enteric neurones throughout the gastrointestinal tract, and the sacral neural crest which contributes a smaller number of cells that are mainly distributed within the hindgut. The migration of vagal neural crest cells into, and along the gut is promoted by GDNF, which is expressed by the gut mesenchyme and is the ligand for the Ret/GFRalpha1 signalling complex present on migrating vagal-derived crest cells. Sacral neural crest cells enter the gut after it has been colonized by vagal neural crest cells, but the molecular control of sacral neural crest cell development has yet to be elucidated. Under the influence of both intrinsic and extrinsic cues, neural crest cells differentiate into glia and different types of enteric neurones at different developmental stages. Recently, the potential for neural stem cells to form an enteric nervous system has been examined, with the ultimate aim of using neural stem cells as a therapeutic strategy for some gut disorders where enteric neurones are reduced or absent.