The sphincter of Oddi: understanding its control and function

A Mechanics-Based Perspective on the Function of Human Sphincters During Functional Luminal Imaging Probe Manometry

Functional luminal imaging probe (FLIP) is used to measure cross-sectional area (CSA) and pressure at sphincters. It consists of a catheter surrounded by a fluid filled cylindrical bag, closed on both ends. Plotting the pressure-CSA hysteresis of a sphincter during a contraction cycle, which is available through FLIP testing, offers information on its functionality, and can provide diagnostic insights. However, limited work has been done to explain the mechanics of these pressure-CSA loops. This work presents a consolidated picture of pressure-CSA loops of different sphincters. Clinical data reveal that although sphincters have a similar purpose (controlling the flow of liquids and solids by opening and closing), two different pressure-CSA loop patterns emerge: negative slope loop (NSL) and positive slope loop (PSL). We show that the loop type is the result of an interplay between (or lack thereof) two mechanical modes: (i) neurogenic mediated relaxation of the sphincter muscle or pulling applied by external forces, and (ii) muscle contraction proximal to the sphincter which causes mechanical distention. We conclude that sphincters which only function through mechanism (i) exhibition NSL whereas sphincters which open as a result of both (i) and (ii) display a PSL. This work provides a fundamental mechanical understanding of human sphincters. This can be used to identify normal and abnormal phenotypes for the different sphincters and help in creating physiomarkers based on work calculation.

Expression and functional study of cholecystokinin-A receptors on the interstitial Cajal-like cells of the guinea pig common bile duct

BACKGROUND

Many studies have shown that interstitial Cajal-like cell (ICLC) abnormalities are closely related to a variety of dynamic gastrointestinal disorders. ICLCs are pacemaker cells for gastrointestinal movement and are involved in the transmission of nerve impulses.

AIM

To elucidate the expression profile and significance of cholecystokinin-A (CCK-A) receptors in ICLCs in the common bile duct (CBD), as well as the role of CCK in regulating CBD motility through CCK-A receptors on CBD ICLCs.

METHODS

The levels of tyrosine kinase receptor (c-kit) and CCK-A receptors in CBD tissues and isolated CBD cells were quantified using the double immunofluorescence labeling technique. The CCK-mediated enhancement of the movement of CBD muscle strips through CBD ICLCs was observed by a muscle strip contraction test.

RESULTS

Immunofluorescence showed co-expression of c-kit and CCK-A receptors in the CBD muscularis layer. Observations of isolated CBD cells showed that c-kit was expressed on the surface of ICLCs, the cell body and synapse were colored and polygonal, and some cells presented protrusions and formed networks adjacent to the CBD while others formed filaments at the synaptic terminals of local cells. CCK-A receptors were also expressed on CBD ICLCs. At concentrations ranging from 10-6 mol/L to 10-10 mol/L, CCK promoted CBD smooth muscle contractility in a dose-dependent manner. In contrast, after ICLC removal, the contractility mediated by CCK in CBD smooth muscle decreased.

CONCLUSION

CCK-A receptors are highly expressed on CBD ICLCs, and CCK may regulate CBD motility through the CCK-A receptors on ICLCs.

The enteric nervous system

Of all the organ systems in the body, the gastrointestinal tract is the most complicated in terms of the numbers of structures involved, each with different functions, and the numbers and types of signaling molecules utilized. The digestion of food and absorption of nutrients, electrolytes, and water occurs in a hostile luminal environment that contains a large and diverse microbiota. At the core of regulatory control of the digestive and defensive functions of the gastrointestinal tract is the enteric nervous system (ENS), a complex system of neurons and glia in the gut wall. In this review, we discuss 1) the intrinsic neural control of gut functions involved in digestion and 2) how the ENS interacts with the immune system, gut microbiota, and epithelium to maintain mucosal defense and barrier function. We highlight developments that have revolutionized our understanding of the physiology and pathophysiology of enteric neural control. These include a new understanding of the molecular architecture of the ENS, the organization and function of enteric motor circuits, and the roles of enteric glia. We explore the transduction of luminal stimuli by enteroendocrine cells, the regulation of intestinal barrier function by enteric neurons and glia, local immune control by the ENS, and the role of the gut microbiota in regulating the structure and function of the ENS. Multifunctional enteric neurons work together with enteric glial cells, macrophages, interstitial cells, and enteroendocrine cells integrating an array of signals to initiate outputs that are precisely regulated in space and time to control digestion and intestinal homeostasis.

Design and Optimization of a New Anti-reflux Biliary Stent With Retractable Bionic Valve Based on Fluid-Structure Interaction Analysis

Duodenal biliary reflux has been a challenging common problem which could cause dreadful complications after biliary stent implantation. A novel anti-reflux biliary stent with a retractable bionic valve was proposed according to the concertina motion characteristics of annelids. A 2D equivalent fluid-structure interaction (FSI) model based on the axial section was established to analyze and evaluate the mechanical performances of the anti-reflux biliary stent. Based on this model, four key parameters (initial shear modulus of material, thickness, pitch, and width) were selected to investigate the influence of design parameters on anti-reflux performance via an orthogonal design to optimize the stent. The results of FSI analysis showed that the retrograde closure ratio of the retractable valve primarily depended on initial shear modulus of material (p < 0.05) but not mainly depended on the thickness, pitch, and width of the valve (p > 0.05). The optimal structure of the valve was finally proposed with a high retrograde closing ratio of 95.89%. The finite element model revealed that the optimized anti-reflux stent possessed improved radial mechanical performance and nearly equal flexibility compared with the ordinary stent without a valve. Both the FSI model and experimental measurement indicated that the newly designed stent had superior anti-reflux performance, effectively preventing the duodenobiliary reflux while enabling the bile to pass smoothly. In addition, the developed 2D equivalent FSI model provides tremendous significance for resolving the fluid-structure coupled problem of evolution solid with large deformation and markedly shortens the calculation time.

Ampullary stenosis and choledocholithiasis post Roux-En-Y gastric bypass: challenges of biliary access and intervention

BACKGROUND

Ampullary stenosis following Roux-en-Y gastric bypass (RYGB) is increasingly encountered. We describe cases of biliary obstruction from ampullary stenosis and choledocholithiasis to illustrate the associated diagnostic and interventional challenges with this condition.

METHODS

We reviewed medical records of patients with prior RYGB who underwent a biliary access procedure or surgery for non-malignant disease from January 2012-December 2018.

RESULTS

We identified 15 patients (4 male, 11 female; mean age 53.7 years) who had RYGB on average 11.7 years (range 1-32) years before diagnosis of biliary obstruction. Fourteen patients reported abdominal pain, 5 had nausea/emesis, 12 had elevated liver function tests, and 6 had ascending cholangitis. Mean common bile duct (CBD) diameter at presentation was 16.9 mm (range 4.0-25.0 mm). Operations included 3 transduodenal ampullectomies (2 with biliary bypass), 2 CBD explorations with stone extraction, 1 laparoscopic cholecystectomy alone, 1 Whipple procedure, 1 balloon enteroscopy with sphincterotomy, and 7 transgastric endoscopic retrograde cholangiopancreatography. All ampulla pathology was benign in patients who underwent resection. At follow-up (mean 15.4 months; range 0.23-44.5 months), 12/15 (80%) reported symptom resolution or improvement.

DISCUSSION

Ampullary stenosis after RYGB presents challenges for diagnostic evaluation and intervention, often requiring multi-disciplinary expertise. The underlying pathology remains to be elucidated.

Prevalence of increased canine pancreas-specific lipase concentrations in young dogs with parvovirus enteritis

BACKGROUND

Pancreatic abnormalities during canine parvovirus (CPV) enteritis have not been studied prospectively.

OBJECTIVES

The objective of this study was to evaluate the diagnostic significance of canine serum pancreas-specific lipase (Spec cPL) concentration in dogs with CPV enteritis for the presence of acute pancreatitis (AP). Puppies with naturally occurring CPV enteritis were recruited and prospectively allocated into 2 groups according to normal or increased serum Spec cPL concentration. Clinical signs, laboratory findings, and pancreas-associated variables were compared between groups, and the impact of possible AP on disease course, duration of hospitalization, and outcome was assessed.

RESULTS

Serum Spec cPL concentration in 35 puppies was above the upper limit of the RI in 17/35 (48.6%) dogs (Group A) and within the RI in 18 dogs (Group B). An increased serum lipase activity was present in 29/35 (82.9%) dogs, and Group A dogs had a higher serum lipase activity than Group B (P = .006). Serum Spec cPL in Group A dogs was positively correlated with serum lipase activity at the day of presentation (r = .667; P = .003) and day of discharge (r = .628; P = .007). No statistically significant difference was found between groups (P = .233) for the presence of systemic inflammatory response syndrome (SIRS) (6/17 or 35.3% dogs Group A, and 8/18 or 44.4% dogs Group B), the disease course, duration of hospitalization, or outcome between groups.

CONCLUSIONS

Increased serum Spec cPL is relatively common in dogs with CPV enteritis. However, such increases do not seem to correlate with the outcome of disease.

Comparative Relaxant Effects of Ataciguat and Zaprinast on Sheep Sphincter of Oddi

BACKGROUND

Relaxing the sphincter of Oddi (SO) is an important process during endoscopic retrograde cholangiopancreatography (ERCP) procedures. This issue suggests that the easier the sphincterotomy and cannulation, the more post-ERCP complications decrease.

AIMS

To compare the relaxant effects of ataciguat (a novel soluble guanylyl cyclase activator) and zaprinast (an inhibitor of phosphodiesterase 5) on sheep SO in vitro, thus testing whether they can be used during ERCP.

STUDY DESIGN

Animal experimentation.

METHODS

Sheep SO rings were placed in tissue baths and their isometric tension to ataciguat and zaprinast were tested. We also tested their isometric tension against ataciguat in the presence of 1H-(1,2,4) oxadiazole (4,3-a) quinoxalin-1-one (ODQ) which is a soluble guanylyl cyclase inhibitor.

RESULTS

Ataciguat and zaprinast both triggered concentration addicted relaxation on sheep SO rings (p=0.0018, p=0.0025 respectively) but the relaxation of the ataciguat was significantly greater than that of zaprinast at all concentrations (p=0.0024). It was observed that decreased relaxation responses were initiated by ataciguat in the presence of ODQ (p=0.0012).

CONCLUSION

Ataciguat and zaprinast both have relaxing effects on sphincter of Oddi, although that of zaprinast is lower. We believe that ataciguat and zaprinast can be used in ERCP procedures in order to relax the sphincter of Oddi and thus can be used locally in order to decrease complications.

Acute pancreatitis in patients after bariatric surgery: incidence, outcomes, and risk factors

BACKGROUND

The incidence of acute pancreatitis (AP) in bariatric surgery patients is not known. Ouraim was to determine the incidence, outcomes, and risk factors of AP in post-bariatric surgery patients.

METHODS

An historical cohort study was conducted of all patients who underwent Roux-en-Y gastric bypass, sleeve gastrectomy, adjustable gastric banding, and revisional procedures at our institution from January 2004 to September 2011. Patients who developed AP were identified by review of the electronic medical record. A nested case-control study using Cox regression analysis was done to identify risk factors.

RESULTS

A total of 2695 patients underwent bariatric surgery. Twenty-eight patients (1.04 %) developed AP during a median follow-up of 3.5 years (interquartile range [IQR] 1.9-5.8). One patient had severe AP, and there was one AP-related death. In the case-control study, the only baseline variable that predicted post-operative AP was a prior history of AP. Three other variables identified after surgery were associated with AP: (1) rapid weight loss as measured by percent of excess weight loss (EWL) at the first post-operative visit, (2) abnormal findings on post-operative ultrasound (stones, sludge or ductal dilation), and (3) post-operative complications of bowel leak or anastomotic stricture.

CONCLUSIONS

The incidence of AP in this cohort is 1.04 %, which is higher than that reported for the general population (~17/100,000, 0.017 %). Most cases were clinically mild and managed conservatively with good outcomes. Rapid post-operative weight loss and the presence of gallstones or sludge on post-operative ultrasound were significant risk factors for AP.

Histochemical Study of Heparin-positive Mast Cells in the Terminal Part of Porcine Ductus Choledochus and Papilla Duodeni Major

The study presented in detail the localization and density of mast cells (MCs) in the intramural part of the common bile duct (CBD) and in the major duodenal papilla (MDP) of domestic swine. MCs' density (number/mm(2) ) in different layers of both of the duct and papilla was evaluated after toluidine blue staining. Their number was higher in the lamina propria mucosae than in the tunica muscularis of the studied structures. The localization of berberine-positive, (heparin containing) MCs and the ratio between them and toluidine blue-positive MCs with γ-ma metachromasia was also established. Ratios of heparin-containing MCs in comparison with all toluidine blue-positive MCs were found as follows: ductus choledochus - 32% in the subglandular connective tissue of lamina propria mucosae in the intramural part of the duct; m. sphincter ductus choledochus - 31% in the circular and 0.06% in the longitudinal muscle layer; subserosa - 59%; papilla duodeni major - 0.03% in the subepithelial connective tissue and 34% in the subglandular connective tissue of lamina propria mucosae, respectively. The established large difference in heparin-positive MCs in both the subepithelial and subglandular connective tissues of CBD and MDP, respectively, is an evidence for the existence of mucosal and connective tissue MCs.

Biliary tract pressure before and after endoscopic papillary balloon dilation treatment for common bile duct stones

AIM: To determine the biliary tract pressure before and after endoscopic papillary balloon dilation (EPBD) treatment for common bile duct stones.

METHODS: Clinical data for 96 patients with common bile duct stones who successfully underwent EPBD and biliary manometry from September 2011 to January 2014 were retrospectively analyzed.

RESULTS: Biliary tract pressure was significantly higher in patients with common bile duct stones than in healthy controls, which could be relieved by EPBD. Biliary tract pressure in patients who underwent cholecystectomy was higher than in patients with gallbladder stones. After operation, there were 2 cases of hyperamylasemia, 2 cases of acute pancreatitis and 2 cases of mild cholangitis, all of which resolved after non-operative treatment. The incidence of complications was 6.3% (6/96). No serious complications occurred.

CONCLUSION: EPBD treatment can effectively solve biliary obstruction and reduce biliary pressure.

Extraparenchymal Bile/Pancreatic Ducts and Duodenal Papillae: Pathologic Evaluation in Nonclinical Species--A Brief Review

This review focuses on the anatomy, histologic preparation, and pathologic evaluation of extraparenchymal bile and pancreatic ducts (BPDs) and their openings at the duodenal papillae in the cynomolgus macaque (Macaca fascicularis), the Beagle dog (Canis familiaris), the Wistar Hanover rat (Rattus norvegicus), and the CD1 mouse (Mus musculus). In nonclinical safety assessment, intraparenchymal BPDs (with sections of liver and pancreas, respectively) are evaluated routinely. However, detailed evaluation of the extraparenchymal BPDs or the duodenal papillae is not included. In the context of nonclinical safety assessment studies, this review describes situations in which evaluation of extraparenchymal ductal structures and duodenal papillae may be useful in characterizing test article-related changes; elucidates anatomic similarities between human, macaque, and dog and notable differences in rats and mice; and consolidates the information required for the histopathologic evaluation of these tissues.

Effects of cholecystectomy on the changes of motility of Beagle dogs' sphincter of Oddi

PURPOSE

To observe the effect of cholecystectomy on the changes of motion pattern of Beagle dogs' sphincter of Oddi (SO), and investigate the modulatory role of nitric oxide (NO) and cholecystokinin (CCK) in the regulation of SO.

METHODS

Pressure of common bile duct, SO motility, response to bolus injections of cholecystokinin (CCK, 20 ng/kg and 100 ng/kg), basal pressure (BP) and phasic contraction amplitude (PCA) were measured respectively by manometry in six Beagle dogs before and after cholecystectomy.

RESULTS

After cholecystectomy, the pressure and diameter of common bile ducts (CBD) was significantly increased (p<0.01); BP and phasic contraction frequency (PCF) were also increased, however, no significant differences were found between the two groups; the SO motilities was not significantly changed. The relaxation responded to physiological dose of CCK (20ng/kg) was decreased, while bolus-dose of CCK (100ng/kg) induced rapid contractions and decreased PCA after cholecystectomy. The regulation pattern of SO pressure modulated by NO and its inhibitor had changed after cholecystectomy.

CONCLUSION

After cholecystectomy in Beagle dogs, no obviously change of motion pattern of SO was observed through self-compensation, but these compensations may lead to some changes of regulation pattern of CCK and NO on SO.

Functional magnetic resonance cholangiography with Gd-EOB-DTPA: a study in healthy volunteers

PURPOSE

To describe the patterns of bile distribution in the biliary tree, duodenum, jejunum, and stomach, and to determine the gallbladder ejection fraction (GBEF) by using functional magnetic resonance cholangiography (MRC) with gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) in healthy volunteers.

MATERIALS AND METHODS

Forty subjects were included in this study. After conventional MRC, pre-fatty meal MRC (PRFM) was obtained at 30, 40, 50, and 60min after contrast agent injection. Then, post-fatty meal MRC (POFM) was obtained every 10min for 1h. We assessed the PRFM and POFM for opacification of contrast agent in the first- and second-order intrahepatic ducts (IHDs) and the common bile duct (CBD). Contrast agent opacification in the cystic duct was assessed, and the percentage volume of contrast agent filling in the gallbladder (GB) was calculated on PRFM. We calculated the GBEF and assessed the presence of contrast agent in the GB, duodenum, jejunum, and stomach.

RESULTS

Thirty-six (90%) subjects showed grade 3 CBD opacification (visible contrast and well-defined bile duct border) on 60-min PRFM. Thirty-four (85%) subjects showed grade 3 first-order IHD opacification on 60-min PRFM. All (100%) subjects showed cystic duct opacification of contrast agent, and the average percentage volume of contrast agent filling in the GB was 68.81%±16.84% on 60-min PRFM. The GBEF at 30-min POFM was 35.00%±18.26%. Ten (25%) subjects had no contrast agent in the stomach and small bowel on all PRFMs. Twelve (30%) subjects had contrast medium in the stomach on PRFM and/or POFM.

CONCLUSIONS

Functional MRC with Gd-EOB-DTPA can allow determining the distribution of bile in the biliary tree and small intestine, as well as the GBEF.

The mucosal folds at the pancreaticobiliary junction

PURPOSE

The structure and function of the mucosal folds in the terminal bile and pancreatic ducts and hepatopancreatic ampulla are poorly characterised. The distribution, muscularity, and innervation of these folds were investigated.

METHODS

The pancreaticobiliary junction was excised from ten cadavers (five male, 66-90 years) and examined histologically by serially sectioning (4-μm thickness) along the length of the terminal bile and pancreatic ducts from the tip of the major duodenal papilla. Three surgical specimens (two male, 63-72 years) were also evaluated. Sections were stained with haematoxylin and eosin, anti-actin (smooth muscle), anti-S100 (innervation), and anti-cholecystokinin (CCK)-A receptor antibodies. ImageJ software was used to compare relative radial fold projection and semi-quantitatively assess the smooth muscle and nerve content. In one additional cadaver specimen, folds were examined by scanning electron microscopy.

RESULTS

Mucosal folds in the terminal bile duct were arranged circumferentially in a lattice-like arrangement and were distributed over an average distance of 7.3 mm along the terminal bile duct compared to 4.2 mm along the pancreatic duct (P = 0.001), projected further into the lumen, and were more densely innervated than those in the terminal pancreatic duct. Folds in both ducts contained smooth muscle which was more prominent in folds nearest to the major duodenal papilla. Mucosal folds in cadaver and surgical specimens showed no evidence of CCK-A receptor immunoreactivity.

CONCLUSIONS

This study demonstrates that the mucosal folds of the terminal bile and pancreatic ducts contain muscle and nerve fibres, suggesting an active rather than purely passive function.

Morphometric development of sphincter of oddi in human fetuses during fetal period: microscopic study

OBJECTIVE

In this study, morphometric developments of the sphincter of Oddi in human fetuses were observed.

MATERIAL AND METHODS

We observed 113 human fetuses consisting of 67 male and 46 female subjects, whose ages varied between 14 to 40 weeks who showed no signs of any pathology or anomaly externally. The common external measurements of fetuses were carried out, followed by abdominal dissection to determine where the sphincters of Oddi were localized within the duodenum and pancreas. Histological specimens of tissue samples were gathered from the inner wall of the duodenum where it was assumed that the sphincters of Oddi had been localized. The parameters of total external diameters, lumen diameters, wall thickness, diameters of ductus choledochus and ductus pancreaticus, and the distance between these two structures, which are also known as the origins of the sphincter of Oddi, were measured by using a light microscope. The standard deviations of the measurements were calculated for each gestational week and trimester.

RESULTS

The calculations suggested that there were statistically significant correlations between gestational age and all of the other parameters with the exception of the ductus choledochus (p<0.001). It was observed that the wall thickness of the ductus choledochus increased at the first half of the fetal stage and decreased at the second half, as the lumen diameter increased through the 40th week. The gender difference was not statistically significant (p>0.05).

CONCLUSION

The data we collected in our study were considered as useful for the evaluation of the development of the sphincter of Oddi area and fetal stage.

Changes of the sphincter of Oddi motility in dog after cholecystectomy

OBJECTIVE

To determine the effect of cholecystectomy on the motility of the sphincter of Oddi (SO).

METHODS

Pressures of common bile duct (CBD), SO motility and its response to bolus injections of cholecystokinin (CCK, 20 ng/kg and 100 ng/kg) were detected respectively by manometry in eight Beagle dogs before and after cholecystectomy.

RESULTS

After cholecystectomy the CBD pressure increased 2.18 ± 1.86 mmHg, while the cyclical motion pattern of SO still existed but with a shortened cycle duration. The basal pressure (BP), phasic contraction amplitude (PCA), phasic contraction frequency (PCF) and its mode of propagation did not change significantly. Under the stimulation of CCK after cholecystectomy, although the motion patterns of SO were similar to those before cholecystectomy, the greatest inhibitory efficacy of BP and PCA all decreased with the prolonged excitement duration and the increased percentage of retrograde contraction.

CONCLUSIONS

Shortly after a cholecystectomy in Beagle dogs, the CBD pressure increased, SO motilities did not change significantly during the interdigestive phase except with a shortened cycle duration. Its relaxation responded to CCK was weakened with a confused contraction pattern.

Effect of somatostatin on human sphincter of Oddi motility

Native somatostatin is a gut hormone and neuropeptide, widely distributed in the nervous and gastrointestinal system, and has a broad range of biological actions. In gastrointestinal tract (GIT), somatostatin is mainly produced by the delta cells of the pancreas and gastrointestinal mucosal. The inhibitory effects of somatostatin on gastrointestinal motility and hormone secretion are mediated by a family of G protein-coupled receptors: the somatostatin receptors (SSTR1-5). The sphincter of Oddi (SO) located near the duodenum papillae is an anatomically and functionally distinct organ, SO motility is controlled and regulated by nerve, hormone and interstitial cells of Cajal. The effect of somatostatin on SO motility is still controversial. This article reviewed effect of somatostatin on human sphincter of oddi motility.

The feasibility and reliability of using circular electrode for sphincter of Oddi electromyography in anaesthetised rabbits

Sphincter of Oddi manometry (SOM) is the gold standard for assessing sphincter of Oddi dysfunction (SOD), but is considered a diagnostic sensitivity of 30-80% and associated with significant complications of pancreatitis. Electromyography (EMG) of sphincter of Oddi (SO) using a circular electrode (CE) may be useful in improving diagnostic accuracy and reducing complications. To evaluate the feasibility and reliability of the CE, we record myoelectric activity of SO in rabbits using the CE to compare with the traditional needle electrode (NE). The CE was prepared using a double-channel biogel catheter with two silver rings at the head of the catheter. The CE was then inserted into the lumen of the SO through the duodenal papilla, and myoelectric activity was recorded in the SO in 30 rabbits. An EMG recorded using an NE was performed at the same time, when the SO was in basal state, after injection of cholecystokinin and N-butylscopolamine bromide. Electromyographs recorded by the two methods were then evaluated. Satisfactory SO EMGs were acquired using the CE without any injury. Simultaneous recording revealed a very similar traces and one-to-one correspondence of SO spike bursts (SOSB). Linear regression analysis showed a significant direct correlation between the two methods for SOSB duration and amplitude. The results suggested that CE was comparable with NE in terms of recording efficacy. The CE also has advantages of easy fixation, accurate localisation, broad applicability and ease of achieving satisfactory outcomes without trauma, compared with the NE.

Lessons from nature: "Pathogen-Mimetic" systems for mucosal nano-medicines

Mucosal surfaces establish an interface with external environments that provide a protective barrier with the capacity to selectively absorb and secrete materials important for homeostasis of the organism. In man, mucosal surfaces such as those in the gastrointestinal tract, respiratory tree and genitourinary system also represent significant barrier to the successful administration of certain pharmaceutical agents and the delivery of newly designed nano-scale therapeutic systems. This review examines morphological, physiological and biochemical aspects of these mucosal barriers and presents currently understood mechanisms used by a variety of virulence factors used by pathogenic bacteria to overcome various aspects of these mucosal barriers. Such information emphasizes the impediments that biologically active materials must overcome for absorption across these mucosal surfaces and provides a template for strategies to overcome these barriers for the successful delivery of nano-scale bioactive materials, also known as nano-medicines.

Sphincter of Oddi dysfunction after Roux-en-Y gastric bypass

BACKGROUND

Patients who have undergone Roux-en-Y gastric bypass for morbid obesity may develop postoperative abdominal pain disorders that require surgical evaluation. Chronic pancreatitis and pain associated with sphincter of Oddi dysfunction (SOD) is an uncommon disorder whose clinical diagnosis is problematic without sphincter of Oddi manometry. To evaluate the diagnosis and treatment of SOD in the gastric bypass population, a retrospective review and analysis of gastric bypass patients who had undergone transduodenal sphincteroplasty (TS) for SOD was undertaken.

METHODS

The medical records of patients who had undergone TS after gastric bypass at the Medical University of South Carolina Digestive Disease Center from January 2002 to December 2006 were evaluated for outcomes-based data with the approval of the institutional review board for the evaluation of human subjects. Long-term patient outcomes were assessed using the Medical Outcomes Study Short Form 36-item, version 2, quality-of-life survey.

RESULTS

A total of 16 women (median age 49 years) were identified who had undergone TS with biliary sphincteroplasty and pancreatic ductal septoplasty for SOD. The indications for surgery included pain (100%), nausea (31%), weight loss (13%), and recurrent pancreatitis (31%). The diagnosis of SOD was supported by magnetic resonance cholangiopancreatography with secretin stimulation. Three postoperative complications (18.8%) developed, but no mortality. The average length of hospital stay was 5 days (range 2-9). Of the 16 patients, 13 (81%) responded to the survey follow-up. The mean length of follow-up was 28 months (range 16-57). Of the 13 patients, 11 (85%) reported pain improvement after surgery. The survey's norm-based scores were similar to those of a representative population.

CONCLUSION

SOD should be considered in the differential diagnosis of gastric bypass patients with pancreatobiliary pain after cholecystectomy. When the clinical history is supported by laboratory and magnetic resonance cholangiopancreatography data, TS can be undertaken with low morbidity and good patient outcomes. SOD is a notable disorder in the gastric bypass population. With appropriate patient selection, TS can be beneficial.

Allergies: their role in cancer prevention

The nature of the biological relationships between cancers and allergies has intrigued researchers and health care providers for five decades. Three hypotheses have been proposed: antigenic stimulation predicts positive associations between cancers and allergies (i.e., allergy sufferers are more likely to get cancer), whereas immunosurveillance and prophylaxis predict inverse associations (i.e., allergy sufferers are less likely to get cancer). Immunosurveillance predicts inverse associations for cancers of all tissues and organ systems, and prophylaxis predicts inverse associations specifically for cancers of tissues and organ systems that interface with the external environment. To comparatively evaluate these hypotheses, we comprehensively reviewed the literature on cancer and allergies. We located 148 papers published from 1955 through 2006 that reported results of 463 studies of relationships between patients' histories of 11 specific allergies and cancers of 19 tissues and organ systems, and 183 studies of patients' histories of multiple allergies in relation to various types/sites of cancers. Analyses of these studies revealed that (1) frequencies of positive, inverse, and null allergy-cancer associations differed considerably among cancers of different tissues and organ systems; (2) more than twice as many studies reported inverse allergy-cancer associations as reported positive associations; (3) inverse associations were particularly common for cancers of the mouth and throat, brain glia, colon and rectum, pancreas, skin, and cervix but (4) particularly rare for cancers of the breast, prostate, and brain meninges, and for myeloma, non-Hodgkin's lymphoma, and myelocytic leukemia; (5) lung cancer was positively associated with asthma but inversely associated with other allergies; (6) inverse associations with allergies were more than twice as common for cancers of nine tissues and organ systems that interface with the external environment compared to cancers of nine tissues and organ systems that do not interface with the external environment; and (7) eczema, hives, and allergies to animal dander and food were most frequently inversely associated with cancers of tissues that interface with the external environment. Taken together, these results are more consistent with the prophylaxis hypothesis than the two alternatives. IgE is a widespread and ancient immunoglobulin isotype in mammals, occurring among all known marsupials, monotremes, and eutherians. The IgE system and its associated allergy symptoms may serve a common protective function: the rapid expulsion of pathogens, dangerous natural toxins, and other carcinogenic antigens before they can trigger malignant neoplasia in exposed tissues.

Ruggero Ferdinando Antonio Guiseppe Vincenzo Oddi

Long forgotten in his motherland but for a single discovery-a small circular tissue whose workings are as mysterious as its discoverer-a brilliant anatomist and physiologist, Oddi, gained his fame at the age of 23 years with his identification of the sphincter that would later be named in his honor. In 1984 Ruggero Oddi, was celebrated and revered in his native town of Perugia with a monument. Ruggero Oddi lived a tumultuous life, full of grief and tragedy, only to culminate in a lonely death while exiled in a foreign land. We now review the life of this contributor to modern anatomy.

The role of nitric oxide in the electrical field stimulation-induced contractions of sphincter of oddi and gallbladder strips in Guinea pigs

The aim of this study was to investigate the modulatory role of nitric oxide (NO) in the electrical field stimulation (EFS)-induced contractions of isolated sphincter of Oddi (SO) and gallbladder strips from guinea pigs. EFS was used to activate the intrinsic nerves in SO and gallbladder strips. EFS produced frequency-dependent biphasic contractile responses in the SO strips. A smaller contraction, "on response", occurred during EFS, which was followed by a bigger contraction, "off response". Both responses were completely and irreversibly abolished by tetrodotoxin (TTX) (10(-6) M). Atropine (10(-6) M) inhibited the "on response", but not the "off response". EFS produced frequency-dependent monophasic contractile responses in gallbladder strips, which were completely and irreversibly abolished by TTX (10(-6) M) and atropine (10(-6) M). A nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine (10(-4) M and 3 x 10(-4) M, in SO and gallbladder strips, respectively), significantly increased all EFS-induced contractions of SO and gallbladder strips. L-Arginine, but not D-arginine reversed the effect induced by the NOS inhibitor, at all frequencies, in both strips. These results suggested that NO released from nitrergic nerve endings might play a regulatory role in the cholinergic neurotransmission of guinea pig SO and gallbladder strips. The "off response" in he SO preparations might be a rebound increase that was modulated by the nonadrenergic, noncholinergic inhibitory mediator NO.

Neurohormonal regulation of the sphincter of Oddi

The control of sphincter of Oddi (SO) motor activity is complex and involves interactions between the SO smooth muscle with nerves, bioactive agents, and presumably interstitial cells of Cajal. Disturbances in SO motility are known to be related to painful clinical conditions, such as SO dysfunction and acute pancreatitis. Understanding normal SO motility and comparing this to disturbed SO motility patterns may identify mechanisms that could be targeted for future pharmacologic intervention. The effect on SO motility of recently identified neurotransmitters/neuropeptides, such as purines and orexins, is currently being determined. Furthermore, because the control of SO motility is complex, investigations with known bioactive agents, such as cholecystokinin and nitric oxide, are continuing. This review summarizes research investigating SO motility and function performed in 2005 and 2006.

The patient with slightly elevated pancreatic enzymes and abdominal complaints

Abdominal complaints in combination with slightly elevated serum pancreatic enzymes represent a classical clinical challenge. These symptoms may be due to coincidental unrelated harmless disorders, benign pancreatic alterations which are fairly easily treatable such as mild acute pancreatitis or uncomplicated chronic pancreatitis. However, serious, often insidious diseases such as pancreatic tumours may also present with this constellation as their first signs. Diagnostic procedures need to be stratified according to acuteness and severity of symptoms. While patients with acute onset of symptoms and severe complaints need immediate and combined laboratory and imaging investigations to allow adequate therapy, chronic and mild complaints usually justify a stepwise diagnostic approach consecutively using abdominal ultrasound, CT/MRI and endoscopic ultrasound as imaging procedures and reserving ERCP for cases which remain unclear or in which interventional therapy is needed. Diagnosis and follow-up are often particularly demanding in patients with cystic tumours of the pancreas. In chronic pancreatitis patients pain therapy and adequate control of pancreatic exocrine insufficiency may pose major problems. Patients with refractory pain may ultimately require surgical intervention. Another important indication for surgery in chronic pancreatitis is suspicion of cancer that cannot be ruled out by dedicated diagnostic procedures. This also applies to cystic tumours of the pancreas, which have a high risk of malignant transformation or may even already represent pancreatic cancer at the time of diagnosis.

Sphincter of Oddi function in the Australian brush-tailed possum is inhibited by intragastric ethanol

The role of sphincter of Oddi (SO) function in alcoholic acute pancreatitis (AP) is unclear. We aimed to compare the effect of i.v. and intragastric (IG) ethanol on SO function (i.e. trans-sphincteric flow; TSF) and investigate possible neural mechanisms. The involvement of gastric mucosal damage was also investigated by pretreatment with pantoprazole. In anaesthetized Australian possums, blood pressure (BP), TSF and blood ethanol concentrations were measured after i.v. or IG ethanol. Possums were subjected to acute vagotomy, atropine, L-nitro arginine methyl ester (L-NAME) or pantoprazole pretreatment prior to IG ethanol. BP was not significantly altered by ethanol. Ethanol decreased TSF in a dose and route-dependent manner. The lowest dose of IG ethanol reduced TSF but this response was not duplicated by i.v. ethanol producing the same blood ethanol concentrations. Acute vagotomy, atropine or L-NAME pretreatment blocked the ethanol-induced decrease in TSF and simultaneously suppressed the blood ethanol concentration. Pantoprazole pretreatment reduced the TSF response and blood ethanol concentrations implicating mechanisms induced by gastric mucosal damage. We conclude that ethanol (and/or its metabolites) reduces TSF via humoral and neural mechanisms involving vagal pathways, muscarinic receptors and nitric oxide. Reduced TSF could contribute to the onset of AP.

Exogenous purines induce differential responses in the proximal and distal regions of the possum sphincter of Oddi

1. The aim of this study was to compare the effect of exogenous ATP and adenosine on spontaneous motility of the proximal and distal regions of the possum sphincter of Oddi (SO). 2. ATP or adenosine (1 microm-1 mm) was applied to distal-SO or proximal-SO muscle rings in organ baths in the absence or presence of tetrodotoxin (TTX) or P1/P2 antagonists. 3. Both ATP and adenosine altered spontaneous activity, predominantly in proximal-SO rings. 4. Exogenous ATP induced a bi-phasic response consisting of a brief TTX-sensitive excitatory component, and a longer-lasting TTX-insensitive inhibitory component. 5. The excitatory ATP response likely involves P2X receptors, whereas the late inhibitory response likely involves P2Y receptors. 6. Exogenous adenosine decreased spontaneous SO activity, via a TTX-insensitive mechanism. 7. Exogenous purines modulate SO motility, acting primarily in the proximal region of the SO, via neural and non-neural mechanisms and multiple purine receptor subtypes.

Exogenous adenosine triphosphate and adenosine stimulate proximal sphincter of oddi motility via neural mechanisms in the anesthetized Australian possum

We aimed to determine if exogenous adenosine triphosphate or adenosine modulated sphincter of Oddi motility and involved neural mechanisms. Sphincter of Oddi motility was recorded in anesthetized possums by manometry. Adenosine triphosphate or adenosine (1 microM-10 mM) was applied topically to the sphincter before and after pretreatment with tetrodotoxin, hexamethonium, atropine, or Nomega-nitro-L-arginine methyl ester. Sphincter contraction amplitude and frequency were quantified. Adenosine triphosphate induced a concentration-dependent increase in proximal sphincter contraction amplitude and frequency (P < 0.05). This response was reduced by tetrodotoxin and atropine but enhanced by hexamethonium and Nomega-nitro-L-arginine methyl ester. Adenosine concentration dependently increased proximal sphincter contraction amplitude (P < 0.05) only. This response was reduced by tetrodotoxin, atropine, and Nomega-nitro-L-arginine methyl ester, whereas hexamethonium had no effect. We conclude that exogenous adenosine triphosphate and adenosine stimulate proximal sphincter of Oddi motility via neural mechanisms, involving cholinergic motor neurons. Adenosine triphosphate may further modulate sphincter motility via nicotinic and nitrergic pathways.

Effects of orexins on myoelectric activity of sphincter of Oddi in fasted rabbits

AIM

To investigate the effects of peripheral orexins on myoelectric activity of the sphincter of Oddi (SO) in fasted rabbits, and carry out a preliminary investigation into the mechanisms underlying these effects.

METHODS

Myoelectric activity of SO in fasted rabbits was recorded before and after intravenous or local application of orexins. The effects of intravenous atropine on orexin-increased myoelectric activity of SO were tested.

RESULTS

Myoelectric activity of SO was activated by both intravenous and local injection of orexin-A or orexin-B. Intravenous application of atropine completely inhibited the excitatory effect of orexins on SO.

CONCLUSION

Peripheral application of orexins can increase myoelectric activity of SO in fasted rabbits, which is partially associated with the activation of the cholinergic pathway.