Systemic sclerosis gastrointestinal dysmotility: risk factors, pathophysiology, diagnosis and management

Nearly all patients with systemic sclerosis (SSc) are negatively affected by dysfunction in the gastrointestinal tract, and the severity of gastrointestinal disease in SSc correlates with high mortality. The clinical complications of this dysfunction are heterogeneous and include gastro-oesophageal reflux disease, gastroparesis, small intestinal bacterial overgrowth, intestinal pseudo-obstruction, malabsorption and the requirement for total parenteral nutrition. The abnormal gastrointestinal physiology that promotes the clinical manifestations of SSc gastrointestinal disease throughout the gastrointestinal tract are diverse and present a range of therapeutic targets. Furthermore, the armamentarium of medications and non-pharmacological interventions that can benefit affected patients has substantially expanded in the past 10 years, and research is increasingly focused in this area. Here, we review the details of the gastrointestinal complications in SSc, tie physiological abnormalities to clinical manifestations, detail the roles of standard and novel therapies and lay a foundation for future investigative work.

Gastroparesis in systemic sclerosis: a detailed analysis using whole-gut scintigraphy

OBJECTIVES

Gastroparesis is a common complication of SSc. We sought to determine the degree of overlap between gastroparesis and dysmotility in other areas of the gut, correlate our findings with gastrointestinal (GI) symptoms, and examine associations between gastroparesis and SSc features.

METHODS

Whole-gut scintigraphy was performed on SSc patients who were enrolled in the Johns Hopkins Scleroderma Cohort, for whom detailed longitudinal clinical and serologic data are collected. A subset of patients completed the University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument 2.0 (UCLA GIT 2.0) to quantify their GI symptoms. We examined associations between the presence and severity of gastroparesis, GI symptoms, and SSc clinical features.

RESULTS

Ninety-seven SSc patients with and without GI symptoms underwent whole-gut scintigraphy and completed the gastric emptying study. Of the 97, 34 (35%) met criteria for gastroparesis. Of the measures assessed, delayed liquid emptying captured more patients with delayed gastric transit than delayed solid emptying (74% vs 55%), and percentage liquid emptying correlated best with GIT Reflux (ρ = -0.33, P = 0.01) and Distension (ρ = -0.30, P = 0.03) scores. Of 33 patients with gastroparesis, 30 (91%) had abnormal transit in other areas of the GI tract. Higher anti-centromere protein B (CENP-B) titres correlated with slower gastric emptying (ρ = -0.26, P = 0.03), but no specific clinical features of SSc were associated with gastroparesis.

CONCLUSIONS

Gastric emptying of liquids when given alongside solids may be more sensitive and provide a more clinically relevant measure of gastroparesis in SSc than solid gastric emptying or liquid gastric emptying alone. SSc patients with gastroparesis frequently have dysmotility in other areas of the GI tract, underscoring the need for whole-gut scintigraphy to evaluate the entire gut.

The 2018 ISDE achalasia guidelines

Achalasia is a relatively rare primary motor esophageal disorder, characterized by absence of relaxations of the lower esophageal sphincter and of peristalsis along the esophageal body. As a result, patients typically present with dysphagia, regurgitation and occasionally chest pain, pulmonary complication and malnutrition. New diagnostic methodologies and therapeutic techniques have been recently added to the armamentarium for treating achalasia. With the aim to offer clinicians and patients an up-to-date framework for making informed decisions on the management of this disease, the International Society for Diseases of the Esophagus Guidelines proposed and endorsed the Esophageal Achalasia Guidelines (I-GOAL). The guidelines were prepared according the Appraisal of Guidelines for Research and Evaluation (AGREE-REX) tool, accredited for guideline production by NICE UK. A systematic literature search was performed and the quality of evidence and the strength of recommendations were graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Given the relative rarity of this disease and the paucity of high-level evidence in the literature, this process was integrated with a three-step process of anonymous voting on each statement (DELPHI). Only statements with an approval rate >80% were accepted in the guidelines. Fifty-one experts from 11 countries and 3 representatives from patient support associations participated to the preparations of the guidelines. These guidelines deal specifically with the following achalasia issues: Diagnostic workup, Definition of the disease, Severity of presentation, Medical treatment, Botulinum Toxin injection, Pneumatic dilatation, POEM, Other endoscopic treatments, Laparoscopic myotomy, Definition of recurrence, Follow up and risk of cancer, Management of end stage achalasia, Treatment options for failure, Achalasia in children, Achalasia secondary to Chagas' disease.

Relating gastric scintigraphy and symptoms to motility capsule transit and pressure findings in suspected gastroparesis

BACKGROUND

Wireless motility capsule (WMC) findings are incompletely defined in suspected gastroparesis. We aimed to characterize regional WMC transit and contractility in relation to scintigraphy, etiology, and symptoms in patients undergoing gastric emptying testing.

METHODS

A total of 209 patients with gastroparesis symptoms at NIDDK Gastroparesis Consortium centers underwent gastric scintigraphy and WMCs on separate days to measure regional transit and contractility. Validated questionnaires quantified symptoms.

KEY RESULTS

Solid scintigraphy and liquid scintigraphy were delayed in 68.8% and 34.8% of patients; WMC gastric emptying times (GET) were delayed in 40.3% and showed 52.8% agreement with scintigraphy; 15.5% and 33.5% had delayed small bowel (SBTT) and colon transit (CTT) times. Transit was delayed in ≥2 regions in 23.3%. Rapid transit was rarely observed. Diabetics had slower GET but more rapid SBTT versus idiopathics (P ≤ .02). GET delays related to greater scintigraphic retention, slower SBTT, and fewer gastric contractions (P ≤ .04). Overall gastroparesis symptoms and nausea/vomiting, early satiety/fullness, bloating/distention, and upper abdominal pain subscores showed no relation to WMC transit. Upper and lower abdominal pain scores (P ≤ .03) were greater with increased colon contractions. Constipation correlated with slower CTT and higher colon contractions (P = .03). Diarrhea scores were higher with delayed SBTT and CTT (P ≤ .04).

CONCLUSIONS & INFERENCES

Wireless motility capsules define gastric emptying delays similar but not identical to scintigraphy that are more severe in diabetics and relate to reduced gastric contractility. Extragastric transit delays occur in >40% with suspected gastroparesis. Gastroparesis symptoms show little association with WMC profiles, although lower symptoms relate to small bowel or colon abnormalities.

Esophageal distensibility measurement: impact on clinical management and procedure length

Luminal distensibility measurement has demonstrated relevance to various disease processes, though its effects on clinical decision-making have been less well understood. This study aims to characterize the clinical impact of impedance planimetry measurement as well as the learning curve associated with its use in the esophagus. A single provider performed distensibility measurement in conjunction with upper endoscopy for a variety of clinical indications with the functional lumen imaging probe (FLIP) over a period of 21 months. Procedural data were prospectively collected and, along with medical records, retrospectively reviewed. Seventy-three procedures (70 patients) underwent esophageal distensibility measurement over the timeline of this study. The most common procedural indications were known or suspected achalasia (32.9%), dysphagia with connective tissue disease (13.7%), eosinophilic esophagitis (12.3%), and dysphagia with prior fundoplication (9.6%). FLIP results independently led to a change in management in 29 (39.7%) cases and supported a change in management in an additional 15 (20.5%) cases. The most common change in management was a new or amended therapeutic procedure (79.5%). Procedural time added by distensibility measurement was greater among earlier cases than among later cases. The median time added overall was 5 minutes and 46 seconds. Procedural time added varied significantly by procedural indication, but changes in management did not. Distensibility measurement added meaningful diagnostic information that impacted therapeutic decision-making in the majority of cases in which it was performed. Procedural time added by this modality is typically modest and decreases with experience.

Diabetic and idiopathic gastroparesis is associated with loss of CD206-positive macrophages in the gastric antrum

BACKGROUND

Animal studies have increasingly highlighted the role of macrophages in the development of delayed gastric emptying. However, their role in the pathophysiology of human gastroparesis is unclear. Our aim was to determine changes in macrophages and other cell types in the gastric antrum muscularis propria of patients with diabetic and idiopathic gastroparesis.

METHODS

Full thickness gastric antrum biopsies were obtained from patients enrolled in the Gastroparesis Clinical Research Consortium (11 diabetic, 6 idiopathic) and 5 controls. Immunolabeling and quantitative assessment was done for interstitial cells of Cajal (ICC) (Kit), enteric nerves protein gene product 9.5, neuronal nitric oxide synthase, vasoactive intestinal peptide, substance P, tyrosine hydroxylase), overall immune cells (CD45) and anti-inflammatory macrophages (CD206). Gastric emptying was assessed using nuclear medicine scintigraphy and symptom severity using the Gastroparesis Cardinal Symptom Index.

RESULTS

Both diabetic and idiopathic gastroparesis patients showed loss of ICC as compared to controls (Mean [standard error of mean]/hpf: diabetic, 2.28 [0.16]; idiopathic, 2.53 [0.47]; controls, 6.05 [0.62]; P=.004). Overall immune cell population (CD45) was unchanged but there was a loss of anti-inflammatory macrophages (CD206) in circular muscle (diabetic, 3.87 [0.32]; idiopathic, 4.16 [0.52]; controls, 6.59 [1.09]; P=.04) and myenteric plexus (diabetic, 3.83 [0.27]; idiopathic, 3.59 [0.68]; controls, 7.46 [0.51]; P=.004). There was correlation between the number of ICC and CD206-positive cells (r=.55, P=.008). Enteric nerves (PGP9.5) were unchanged: diabetic, 33.64 (3.45); idiopathic, 41.26 (6.40); controls, 46.80 (6.04).

CONCLUSION

Loss of antral CD206-positive anti-inflammatory macrophages is a key feature in human gastroparesis and it is associates with ICC loss.

Anorectal manometry: Should it be performed in a seated position?

BACKGROUND

Anorectal manometry (ARM) is typically preformed in a lateral position. This non-physiological testing position has produced an unexpected negative rectoanal pressure gradient (RAPG, i.e. difference between rectal and anal pressure) with normal defecation. This study was designed (i) to study differences in ARM parameters between water-perfused and solid-state sensors and between lateral and seated positions and (ii) to investigate the roles of ARM parameters in predicting balloon expulsion.

METHODS

ARM was performed in 18 healthy volunteers (HV) and 60 patients with functional constipation (FC) under three randomized conditions: water-perfused in lateral position, solid-state in lateral position, and solid-state in seated position, followed by a balloon expulsion test in seated position.

KEY RESULTS

i) Under the same lateral position, solid-state sensors produced higher rectal resting pressure and RAPG than water-perfused sensors. ii) Using the solid-state sensors, ARM in the seated position revealed higher resting rectal pressure (34.9 vs 10.9 mmHg in HV, 30.9 vs 10.6 mmHg in FC, both P<.001) and higher RAPG (22.6 vs -6.2 mmHg in HV, 17.1 vs -8.1 mmHg in FC, both P<.001) than the lateral position. iii) When ARM was performed using solid-state sensors in seated position, RAPG was predictive of balloon expulsion; using 10 mmHg as a threshold, RAPG could predict balloon expulsion with specificity of 82% and sensitivity 77%.

CONCLUSIONS AND INFERENCE

ARM performed in a seated position using solid-state sensors seems more accurate in assessing rectal pressure, and the RAPG measured under these conditions is predictive of balloon expulsion in FC patients.

Rome IV. Gallbladder and Sphincter of Oddi Disorders

The concept that motor disorders of the gallbladder, cystic duct and sphincter of Oddi can cause painful syndromes is attractive and popular, at least in the USA. However, the results of commonly performed ablative treatments (cholecystectomy and sphincterotomy) are not uniformly good. The predictive value of tests that are often used to diagnose dysfunction (dynamic gallbladder scintigraphy and sphincter manometry) is controversial. Evaluation and management of these patients is made difficult by the fluctuating symptoms and the placebo effect of invasive interventions. A recent stringent study has shown that sphincterotomy is no better than sham treatment in patients with post-cholecystectomy pain and little or no objective abnormalities on investigation, so that the old concept of sphincter of Oddi dysfunction (SOD) type III is discarded. ERCP approaches are no longer appropriate in that context. There is a pressing need for similar prospective studies to provide better guidance for clinicians dealing with these patients. We need to clarify the indications for cholecystectomy in patients with Functional Gallbladder Disorder (FGBD) and the relevance of sphincter dysfunction in patients with some evidence for biliary obstruction (previously SOD type II, now called "Functional Biliary Sphincter Disorder - FBSD") and with idiopathic acute recurrent pancreatitis.

Systematic review with meta-analysis: pharmacological interventions for eosinophilic oesophagitis

BACKGROUND

Eosinophilic oesophagitis (EoE) is a growing cause of dysphagia. Current therapies include dietary manipulation, steroids and biological drugs.

AIM

To perform a systematic review and summarise the effect of different medical interventions on EoE.

METHODS

Two reviewers searched Pubmed and Embase for studies on treatment for EoE. We included randomised controlled trials (RCT) limited to pharmacological interventions. Two reviewers selected studies. Meta-analysis was done using random effects model to estimate odds ratio (OR). Heterogeneity was determined by Cochran's Q statistic and I(2) .

RESULTS

Seventeen references met our inclusion criteria. Eleven RCTs involving 455 participants were included in the meta-analysis. 325 participants were evaluated for symptomatic improvement and 330 were evaluated for histological remission. Symptomatic improvement with topical steroids (7 studies, 250 participants) compared to the control group (placebo or PPI) was noted (OR: 3.03, 95% confidence interval, CI: 1.57-5.87). Histological remission was also noted in nine studies involving 330 participants (OR: 13.66, 95% CI: 2.65-70.34) comparing topical steroids to a control (placebo or PPI). There was no difference between anti-IL-5 drugs and placebo in terms of symptomatic improvement (OR: 0.69, 95% CI: 0.34-1.42).

CONCLUSIONS

Topical steroids induce significant symptomatic and histological remission, and should be considered as a first line treatment. Anti-IL-5 therapy has a minor effect on eosinophilic oesophagitis. Future research in eosinophilic oesophagitis should standardise methodology according to published guidelines to improve quality and allow direct comparison between therapies.

3-D imaging, illustration, and quantitation of enteric glial network in transparent human colon mucosa

BACKGROUND

Enteric glia form a network in the intestinal mucosa and have been suggested to engage in multidirectional interactions with the epithelium, blood vessels, nerves, and immune system. However, due to the dispersed nature of the glial network, standard histology cannot provide a global view of the network architecture. We prepared transparent human colon mucosa for three-dimensional (3-D) confocal microscopy with S100B immunostaining to reveal the location-dependent glial network for qualitative and quantitative analyses.

METHODS

Full-thickness human colons were acquired from colectomies performed for colorectal cancer. We targeted the mucosa away from the tumor site to characterize the glial network morphology. Optical clearing (use of immersion solution to reduce scattering) was applied to generate transparent specimens for deep-tissue microscopy.

KEY RESULTS

Two features of the glial network were seen: (i) A dense glial population resides at the crypt base/mucosal boundary in contact with the lymphatic vessels, and (ii) from the base, the glial network elongates along the crypt axis with peri-cryptic and peri-vascular connections toward the opening. We quantified the mucosal glia as the S100B-positive cells with at least two processes extending from the cell body. Examples of the global and in-depth imaging of adenoma were given to illustrate the morphological correlation between the loss of glial fibers and the aberrant crypts.

CONCLUSIONS & INFERENCES

We have established a useful approach for 3-D imaging, panoramic illustration, and quantitation of the enteric glia in the human colon mucosa to help characterize their roles with mucosal components in health and disease.

3-D imaging and illustration of the perfusive mouse islet sympathetic innervation and its remodelling in injury

AIMS/HYPOTHESIS

Sympathetic nerves influence islet hormone levels in the circulation. Insights into islet sympathetic innervation and its remodelling in diabetes may impact future therapeutics. However, standard immunohistochemistry and microtome-based microscopy cannot provide an integral view of the islet neurovascular complex. We prepared transparent islet specimens to investigate the spatial relationship between sympathetic nerves, blood vessels and islet cells in normal, streptozotocin-injected and non-obese diabetic mouse models.

METHODS

Cardiac perfusion of fluorescent lectin was used to label pancreatic blood vessels. Tyrosine hydroxylase and nuclear staining were used to reveal islet sympathetic innervation and microstructure. Optical clearing (i.e. use of immersion solution to reduce scattering) was applied to enable 3-dimensional confocal microscopy of islets to visualise the sympathetic neurovascular complex in space.

RESULTS

Unlike previously reported morphology, we observed perfusive intra-islet, perivascular sympathetic innervation, in addition to peri-islet contacts of sympathetic nerves with alpha cells and sympathetic fibres encircling the adjacent arterioles. The intra-islet axons became markedly prominent in streptozotocin-injected mice (2 weeks after injection). In non-obese diabetic mice, lymphocytic infiltration remodelled the peri-islet sympathetic axons in early insulitis.

CONCLUSIONS/INTERPRETATION

We have established an imaging approach to reveal the spatial features of mouse islet sympathetic innervation. The neurovascular complex and sympathetic nerve-alpha cell contact suggest that sympathetic nerves modulate islet hormone secretion through blood vessels, in addition to acting directly on alpha cells. In islet injuries, sympathetic nerves undergo different remodelling in response to different pathophysiological cues.

Clinical-histological associations in gastroparesis: results from the Gastroparesis Clinical Research Consortium

BACKGROUND

Cellular changes associated with diabetic (DG) and idiopathic gastroparesis (IG) have recently been described from patients enrolled in the Gastroparesis Clinical Research Consortium. The association of these cellular changes with gastroparesis symptoms and gastric emptying is unknown. The aim of this study was to relate cellular changes to symptoms and gastric emptying in patients with gastroparesis.

METHODS

Earlier, using full thickness gastric body biopsies from 20 DG, 20 IG, and 20 matched controls, we found decreased interstitial cells of Cajal (ICC) and enteric nerves and an increase in immune cells in both DG and IG. Here, demographic, symptoms [gastroparesis cardinal symptom index score (GCSI)], and gastric emptying were related to cellular alterations using Pearson's correlation coefficients.

KEY RESULTS

Interstitial cells of Cajal counts inversely correlated with 4 h gastric retention in DG but not in IG (r = -0.6, P = 0.008, DG, r = 0.2, P = 0.4, IG). There was also a significant correlation between loss of ICC and enteric nerves in DG but not in IG (r = 0.5, P = 0.03 for DG, r = 0.3, P = 0.16, IG). Idiopathic gastroparesis with a myenteric immune infiltrate scored higher on the average GCSI (3.6 ± 0.7 vs 2.7 ± 0.9, P = 0.05) and nausea score (3.8 ± 0.9 vs 2.6 ± 1.0, P = 0.02) as compared to those without an infiltrate.

CONCLUSIONS & INFERENCES

In DG, loss of ICC is associated with delayed gastric emptying. Interstitial cells of Cajal or enteric nerve loss did not correlate with symptom severity. Overall clinical severity and nausea in IG is associated with a myenteric immune infiltrate. Thus, full thickness gastric biopsies can help define specific cellular abnormalities in gastroparesis, some of which are associated with physiological and clinical characteristics of gastroparesis.

Optical clearing improves the imaging depth and signal-to-noise ratio for digital analysis and three-dimensional projection of the human enteric nervous system

BACKGROUND

Due to the dispersed nature of neurites and fibers, the microtome-based 2-dimensional histology provides only a limited perspective of the enteric nervous system. To visualize the enteric plexus, we applied optical clearing to avoid scattering in the human ileum to facilitate photon penetration for 3-dimensional (3-D) microscopy of the neural tissue.

METHODS

Human ileal specimens were derived by trimming the donor bowel due to its excess length during the clinical trial of small intestinal transplantation. The pan-neuronal marker PGP9.5 was used as the immunostaining target to reveal the enteric plexuses. The labeled tissues were immersed in the optical-clearing solution prior to deep-tissue confocal microscopy. The serial sections were digitally analyzed and processed by reconstruction algorithms for 3-D visualization.

KEY RESULTS

Optical clearing of the ileal specimen led to less fluorescence signal decay along the focal path in the tissue and a higher signal-to-noise ratio of the confocal micrographs in comparison with the untreated saline control. Taking advantage of the high signal-to-noise ratio images, we applied software-based signal analysis to identify the presence of the nerve fibers and quantify the signal peaks. The image stacks derived from the serial anatomic micrographs created panoramic views of the gut wall innervations with their associated microstructures.

CONCLUSIONS & INFERENCES

We provide an optical approach to improve the imaging depth in 3-D neurohistology of the human ileum. This methodology has significant promise in facilitating our understanding of the enteric nervous system in health and disease.

The analgesic effects of the GABAB receptor agonist, baclofen, in a rodent model of functional dyspepsia

BACKGROUND

The amino acid γ-aminobutyric acid (GABA) is an important modulator of pain but its role in visceral pain syndromes is just beginning to be studied. Our aims were to investigate the effect and mechanism of action of the GABA(B) receptor agonist, baclofen, on gastric hypersensitivity in a validated rat model of functional dyspepsia (FD).

METHODS

10-day-old male rats received 0.2 mL of 0.1% iodoacetamide in 2% sucrose daily by oral gavages for 6 days. Control group received 2% sucrose. At 8-10 weeks rats treated with baclofen (0.3, 1, and 3 mg kg(-1) bw) or saline were tested for behavioral and electromyographic (EMG) visceromotor responses; gastric spinal afferent nerve activity to graded gastric distention and Fos protein expression in dorsal horn of spinal cord segments T8-T10 to noxious gastric distention.

KEY RESULTS

Baclofen administration was associated with a significant attenuation of the behavioral and EMG responses (at 1 and 3 mg kg(-1)) and expression of Fos in T8 and T9 segments in neonatal iodoacetamide sensitized rats. However, baclofen administration did not significantly affect splanchnic nerve activity to gastric distention. Baclofen (3 mg kg(-1)) also significantly reduced the expression of spinal Fos in response to gastric distention in control rats to a lesser extent than sensitized rats.

CONCLUSIONS & INFERENCES

Baclofen is effective in attenuating pain associated responses in an experimental model of FD and appears to act by central mechanisms. These results provide a basis for clinical trials of this drug in FD patients.

Hepatic electrical stimulation reduces blood glucose in diabetic rats

BACKGROUND

The aim of this study was to investigate the feasibility and mechanisms of controlling blood glucose using hepatic electrical stimulation (HES).

METHODS

The study was performed in regular Sprague-Dawley (SD) rats, streptozotocin-induced type 1 diabetic rats and Zucker diabetic fatty (ZDF) rats chronically implanted with one pair of stimulation electrodes on two lobes of the liver tissues.

KEY RESULTS

(i) Hepatic electrical stimulation was effective in reducing blood glucose by 27%-31% at time points 60, 75 and 90 min after oral glucose in normal rats; (ii) HES reduced blood glucose in both fasting and fed states in both type 1 and type 2 diabetic rats; (iii) Chronic HES decreased the blood glucose level, and, delayed gastric empty and increased plasma glucagon-like peptide-1 (GLP-1) level; and (iv) No adverse events were noted in any rats during HES. Histopathological analyses and liver function tests revealed no electrode dislodgement, tissue damages or liver enzyme changes with HES.

CONCLUSIONS & INFERENCES

Hepatic electrical stimulation is capable of reducing both fasting and fed blood glucose in normal, and type 1 and type 2 diabetic rats and the effect may be partially mediated via an increase in GLP-1 release.

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.

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.

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.

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.

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.

Post-surgical and obstructive gastroparesis

Post-surgical gastroparesis (PSG) is recognized as a consequence of vagal nerve injury following upper abdominal surgery. It has been well documented following vagotomy for peptic ulcer surgery. With the increasing role of surgical treatment in the management of GERD and morbid obesity, PSG is now being diagnosed after fundoplication and bariatric surgery. PSG has also been reported after heart and lung transplantation, possibly due to opportunistic viral infection or motor-inhibitory effects of the immunosuppressive drugs, in addition to vagal nerve injury. Initial postoperative management of PSG should be conservative as many symptoms following abdominal surgery resolve with time. This occurs possibly because the enteric nervous system is able to adapt to the loss of vagal input or vagal reinnervation occurs. Persistent symptoms are difficult to manage and require a multidisciplinary team approach. Gastric electrical stimulation has shown promise in small series.

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.

Downregulation of TNF-Related Apoptosis-Inducing Ligand (TRAIL)/Apo2L in Barrett's Esophagus With Dysplasia and Adenocarcinoma

TRAIL/Apo2L is a CD95 ligand-related member of the TNF family that initiates apoptosis in immune and neoplastic cells after binding to specific surface receptors. The authors previously reported a specific topographic pattern of TRAIL expression in the normal colonic mucosa and the loss of TRAIL expression in tubular adenomas as well as in most colon carcinomas. Therefore, they hypothesized that similar changes may occur during the malignant transformation of Barrett's esophagus. The aim of this study was to compare TRAIL/Apo2L expression in normal gastroesophageal (GE) junction, Barrett's esophagus with and without dysplasia, and associated adenocarcinoma. Immunohistochemical evaluation of TRAIL expression was performed on formalin-fixed paraffin-embedded sections from 29 GE junction/esophageal biopsies, 20 gastric biopsies, 6 esophagectomies, 2 small bowel resection specimens, and 5 colon biopsies. The expression was graded semiquantitatively on a 4-point scale (0-3). TRAIL was expressed in the foveolar epithelium of the histologically normal GE junctional mucosa and stomach as well as in the normal intestinal epithelium, with maximal expression in the surface epithelium. TRAIL was always detected in Barrett's metaplasia (21/21, 100%), and the overall expression was similar to that of the columnar portion of the normal GE junction (8/8, 100%). TRAIL was rarely and weakly (1+) expressed in Barrett's esophagus with dysplasia (3/18, 16.7%) and adenocarcinoma (1/10, 10.0%) (P<0.001). Similarities in the topographic pattern of TRAIL expression in the normal GE junction, stomach, small intestine, and colon suggest a common function of TRAIL throughout the gastrointestinal tract. These results show that the downregulation of TRAIL is associated with development of dysplasia in Barrett's esophagus. Thus, the immunohistochemically detected downregulation of TRAIL expression appears to be a promising indicator of dysplasia in Barrett's esophagus.

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.

Drug Insight: from disturbed motility to disordered movement—a review of the clinical benefits and medicolegal risks of metoclopramide

Metoclopramide, the only drug approved by the FDA for treatment of diabetic gastroparesis, but used off-label for a variety of other gastrointestinal indications, has many potentially troublesome adverse neurologic effects, particularly movement disorders. In this article, we comprehensively review the indications and side effects of metoclopramide, and describe some common pitfalls and strategies to minimize the medicolegal risks to the prescribing physician. Metoclopramide accounts for nearly a third of all drug-induced movement disorders, a common reason for a malpractice suit. The entire spectrum of drug-induced movement disorders, ranging from subtle to life-threatening, can ensue from its use; akathisia and dystonia are generally seen early in the course of metoclopramide-induced movement disorders, whereas tardive dyskinesia and parkinsonism seem to be more prevalent in chronic users. Female sex, age and diabetes are the major risk factors for metoclopramide-induced movement disorders. It is therefore incumbent on gastroenterologists and other prescribing physicians to become familiar with the adverse neurologic effects associated with the use of metoclopramide, and to take appropriate preventive and defensive measures.

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.

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.

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.

Neurolytic Approaches for the Treatment of Pain in Patients with Chronic Pancreatitis

In large part, treatment options for patients with painful chronic pancreatitis remain empirical because of our limited understanding of the pathobiology of pancreatic pain. The procedures of neural block/ablation exemplify these limitations, which include the lack of a clear biologic rationale for various approaches, as well as unequivocal data on long-term outcomes and efficacy. Although the techniques themselves appear to be well established, controlled trials of various medical, endoscopic, radiologic, and surgical options to define the best treatment are clearly needed. In addition, the lack of uniform improvement with any technique underscores the need for applying a multidisciplinary approach to these patients, as should be the case for any chronic pain disorder.

Effect of sleep on gastroesophageal physiology and airway protective mechanisms

The sleeping state is accompanied by many changes in gastroesophageal function that may be of importance in the pathogenesis of gastroesophageal reflux disease (GERD). At nighttime, gastric acid production is increased, gastric emptying is delayed, esophageal clearance is markedly delayed, and upper esophageal sphincter pressure diminishes significantly. Further, unlike daytime esophageal acid exposure, which appears more easily controlled with medical treatment, nocturnal gastric acid production appears difficult to suppress pharmacologically. Nighttime reflux may be associated with a greater prevalence of supraesophageal reflux symptoms as well. At the same time, protective airway reflexes may limit esophageal reflux in some patients. Derangements in the protective mechanisms should be elucidated, as these might account for susceptibility to GERD in patients with nighttime reflux.