Deletion of a single allele of the Dkk1 gene leads to an increase in bone formation and bone mass

Wnt/beta-catenin signaling has been proven to play a central role in bone biology. Unexpectedly, the Wnt antagonist Dkk2 is required for terminal osteoblast differentiation and mineralized matrix formation. We show that Dkk1, unlike Dkk2, negatively regulates osteoblast differentiation and bone formation.

INTRODUCTION

The Wnt co-receptor LRP5 is a critical regulator of bone mass. Dickkopf (Dkk) proteins act as natural Wnt antagonists by bridging LRP5/6 and Kremen, inducing the internalization of the complex. Wnt antagonists are thus expected to negatively regulation bone formation. However, Dkk2 deficiency results in increased bone, questioning the precise role of Dkks in bone metabolism.

MATERIALS AND METHODS

In this study, we investigated specifically the role of Dkk1 in bone in vitro and in vivo. Using rat primary calvaria cells, we studied the effect of retroviral expression of Dkk1 on osteoblast differentiation. In addition, the effect of Dkk1 osteoblast was studied in MC3T3-E1 cells by means of recombinant protein. Finally, to address the role of Dkk1 in vivo, we analyzed the bone phenotype of Dkk1(+/-) animals.

RESULTS

Retroviral expression of Dkk1 in rat primary calvaria cells resulted in a complete inhibition of osteoblast differentiation and formation of mineralized nodules, with a marked decrease in the expression of alkaline phosphatase. Dkk1 expression also increased adipocyte differentiation in these cell cultures. Recombinant murine Dkk1 (rmDkk1) inhibited spontaneous and induced osteoblast differentiation of MC3T3-E1 cells. To determine the role of Dkk1 in vivo and overcome the embryonic lethality of homozygous deletion, we studied the bone phenotype in heterozygous Dkk1-deficient mice. Structural, dynamic, and cellular analysis of bone remodeling in Dkk1(+/-) mice showed an increase in all bone formation parameters, with no change in bone resorption, leading to a marked increase in bone mass. Importantly, the number of osteoblasts, mineral apposition, and bone formation rate were all increased several fold.

CONCLUSIONS

We conclude that Dkk1 protein is a potent negative regulator of osteoblasts in vitro and in vivo. Given that a heterozygous decrease in Dkk1 expression is sufficient to induce a significant increase in bone mass, antagonizing Dkk1 should result in a potent anabolic effect.

Normal values and day-to-day variability of 24-h ambulatory oesophageal impedance-pH monitoring in a Belgian-French cohort of healthy subjects

BACKGROUND

Impedance-pH monitoring is the most sensitive method for detection and characterization of gastro-oesophageal reflux episodes. Normal values from European subjects are lacking.

AIM

To build a database of gastro-oesophageal reflux patterns from French and Belgian healthy subjects.

METHODS

Seventy-two healthy subjects (35 men, mean age 35 years, 18-72) underwent 24-h ambulatory impedance-pH studies. Gastro-oesophageal reflux episodes were detected using impedance and characterized by pH as acid, weakly acidic, or weakly alkaline. Analysis was performed visually and effects of age, gender and intra-individual reproducibility were evaluated.

RESULTS

The total number of gastro-oesophageal reflux episodes was 44 (25,58,75) of which 59% were acid, 28% were weakly acidic and 10% weakly alkaline. Half of gastro-oesophageal reflux episodes were mixed (liquid/gas) and 22% reached 15 cm above the lower oesophageal sphincter. The bolus clearance time was 11 s while acid was chemically cleared in 34 s. Male gender was associated with increased number and proximal extent of total and acid gastro-oesophageal reflux. Repeated studies in 27 subjects showed good reproducibility for number, acidity and air-liquid composition of reflux (Kendall's W-values = 0.72-0.85).

CONCLUSIONS

This study demonstrates good reproducibility of 24-h ambulatory impedance-pH studies and provides values of reflux patterns in healthy subjects for comparisons with European gastro-oesophageal reflux disease patients.

Ambulatory reflux monitoring for diagnosis of gastro-esophageal reflux disease: Update of the Porto consensus and recommendations from an international consensus group

BACKGROUND

An international group of experts evaluated and revised recommendations for ambulatory reflux monitoring for the diagnosis of gastro-esophageal reflux disease (GERD).

METHODS

Literature search was focused on indications and technical recommendations for GERD testing and phenotypes definitions. Statements were proposed and discussed during several structured meetings.

KEY RESULTS

Reflux testing should be performed after cessation of acid suppressive medication in patients with a low likelihood of GERD. In this setting, testing can be either catheter-based or wireless pH-monitoring or pH-impedance monitoring. In patients with a high probability of GERD (esophagitis grade C and D, histology proven Barrett's mucosa >1 cm, peptic stricture, previous positive pH monitoring) and persistent symptoms, pH-impedance monitoring should be performed on treatment. Recommendations are provided for data acquisition and analysis. Esophageal acid exposure is considered as pathological if acid exposure time (AET) is greater than 6% on pH testing. Number of reflux episodes and baseline impedance are exploratory metrics that may complement AET. Positive symptom reflux association is defined as symptom index (SI) >50% or symptom association probability (SAP) >95%. A positive symptom-reflux association in the absence of pathological AET defines hypersensitivity to reflux.

CONCLUSIONS AND INFERENCES

The consensus group determined that grade C or D esophagitis, peptic stricture, histology proven Barrett's mucosa >1 cm, and esophageal acid exposure greater >6% are sufficient to define pathological GERD. Further testing should be considered when none of these criteria are fulfilled.

Classification of esophageal motor findings in gastro-esophageal reflux disease: Conclusions from an international consensus group

BACKGROUND

High-resolution manometry (HRM) has resulted in new revelations regarding the pathophysiology of gastro-esophageal reflux disease (GERD). The impact of new HRM motor paradigms on reflux burden needs further definition, leading to a modern approach to motor testing in GERD.

METHODS

Focused literature searches were conducted, evaluating pathophysiology of GERD with emphasis on HRM. The results were discussed with an international group of experts to develop a consensus on the role of HRM in GERD. A proposed classification system for esophageal motor abnormalities associated with GERD was generated.

KEY RESULTS

Physiologic gastro-esophageal reflux is inherent in all humans, resulting from transient lower esophageal sphincter (LES) relaxations that allow venting of gastric air in the form of a belch. In pathological gastro-esophageal reflux, transient LES relaxations are accompanied by reflux of gastric contents. Structural disruption of the esophagogastric junction (EGJ) barrier, and incomplete clearance of the refluxate can contribute to abnormally high esophageal reflux burden that defines GERD. Esophageal HRM localizes the LES for pH and pH-impedance probe placement, and assesses esophageal body peristaltic performance prior to invasive antireflux therapies and antireflux surgery. Furthermore, HRM can assess EGJ and esophageal body mechanisms contributing to reflux, and exclude conditions that mimic GERD.

CONCLUSIONS & INFERENCES

Structural and motor EGJ and esophageal processes contribute to the pathophysiology of GERD. A classification scheme is proposed incorporating EGJ and esophageal motor findings, and contraction reserve on provocative tests during HRM.

Determinants of gastro-oesophageal reflux perception in patients with persistent symptoms despite proton pump inhibitors

BACKGROUND AND AIMS

Approximately 20% of patients have persistent symptoms of gastro-oesophageal reflux despite proton pump inhibitor (PPI) therapy. The aim of this study was to assess the determinants of reflux perception in patients on PPI therapy.

PATIENTS AND METHODS

20 patients with typical gastro-oesophageal reflux symptoms (heartburn and/or regurgitation) despite double-dose PPIs (twice daily) were included in this study. Ambulatory 24 h pH-impedance studies were performed in all patients. The characteristics of symptomatic and asymptomatic reflux episodes were compared. Symptoms were considered globally and separately for heartburn and regurgitation.

RESULTS

A total of 1273 reflux episodes were detected including 243 (19.1%) acidic, 1018 (80.0%) weakly acidic and 12 (0.9%) weakly alkaline reflux episodes. Overall, 312 (24.5%) reflux episodes were symptomatic. The only factor associated with reflux perception was high proximal extent (p = 0.037). Compared with regurgitation, reflux episodes associated with heartburn were more frequently pure liquid (p = 0.009) and acidic (p = 0.027), had a lower nadir pH (p<0.001), were more frequently preceded by acid reflux episodes (p<0.001) and had a longer reflux bolus clearance time (p<0.001).

CONCLUSIONS

High proximal extent of the refluxate is the only factor associated with reflux perception in patients on double-dose PPI. However, compared with regurgitation, composition of the refluxate, sensitisation of the oesophagus by preceding acid exposure and delayed bolus clearance appear to play a role in heartburn perception.

European guidelines on achalasia: United European Gastroenterology and European Society of Neurogastroenterology and Motility recommendations

INTRODUCTION

Achalasia is a primary motor disorder of the oesophagus characterised by absence of peristalsis and insufficient lower oesophageal sphincter relaxation. With new advances and developments in achalasia management, there is an increasing demand for comprehensive evidence-based guidelines to assist clinicians in achalasia patient care.

METHODS

Guidelines were established by a working group of representatives from United European Gastroenterology, European Society of Neurogastroenterology and Motility, European Society of Gastrointestinal and Abdominal Radiology and the European Association of Endoscopic Surgery in accordance with the Appraisal of Guidelines for Research and Evaluation II instrument. A systematic review of the literature was performed, and the certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation methodology. Recommendations were voted upon using a nominal group technique.

RESULTS

These guidelines focus on the definition of achalasia, treatment aims, diagnostic tests, medical, endoscopic and surgical therapy, management of treatment failure, follow-up and oesophageal cancer risk.

CONCLUSION

These multidisciplinary guidelines provide a comprehensive evidence-based framework with recommendations on the diagnosis, treatment and follow-up of adult achalasia patients.

Manometric features of eosinophilic esophagitis in esophageal pressure topography

BACKGROUND

Although most of the patients with eosinophilic esophagitis (EoE) have mucosal and structural changes that could potentially explain their symptoms, it is unclear whether EoE is associated with abnormal esophageal motor function. The aims of this study were to evaluate the esophageal pressure topography (EPT) findings in EoE and to compare them with controls and patients with gastro-esophageal disease (GERD).

METHODS

Esophageal pressure topography studies in 48 EoE patients, 48 GERD patients, and 50 controls were compared. The esophageal contractile pattern was described for ten 5-mL swallows for each subject and each swallow was secondarily characterized based on the bolus pressurization pattern: absent, pan-esophageal pressurization, or compartmentalized distal pressurization.

KEY RESULTS

Thirty-seven percent of EoE patients were classified as having abnormal esophageal motility. The most frequent diagnoses were of weak peristalsis and frequent failed peristalsis. Although motility disorders were more frequent in EoE patients than in controls, the prevalence and type were similar to those observed in GERD patients (P=0.61, chi-square test). Pan-esophageal pressurization was present in 17% of EoE and 2% of GERD patients while compartmentalized pressurization was present in 19% of EoE and 10% of GERD patients. These patterns were not seen in control subjects.

CONCLUSIONS & INFERENCES

The prevalence of abnormal esophageal motility in EoE was approximately 37% and was similar in frequency and type to motor patterns observed in GERD. Eosinophilic esophagitis patients were more likely to have abnormal bolus pressurization patterns during swallowing and we hypothesize that this may be a manifestation of reduced esophageal compliance.

The epidemiology of Chlamydia trachomatis within a sexually transmitted diseases core group

Female sex workers in Nairobi were prospectively evaluated for risk factors of incident Chlamydia trachomatis infection. Independent risk factors included cervical ectopy (P=.007), gonococcal infection (P=.002), human immunodeficiency virus (HIV) seropositivity (P=.003), HIV seroconversion (P=.001), and duration of prostitution (P=.002). Eighteen different C. trachomatis outer membrane protein (omp1) genotypes were identified, with the allelic composition of the C. trachomatis population changing significantly over time (P=.005). Seventeen of 19 reinfections > or = 6 months apart were with different C. trachomatis omp1 genotypes. Women with HIV infection had an increased proportion of visits with C. trachomatis infection (P=.001) and an increased risk of reinfection (P=.008). Overall, the data demonstrate significant fluctuations in the genotype composition of the C. trachomatis population and a reduced rate of same-genotype reinfection consistent with the occurrence of strain-specific immunity.

Congenital cysts and fistulas of the neck

This retrospective study describes a series of 191 children treated for congenital cysts and fistulas of the neck between 1984 and 1999 in the pediatric ORL Department of La Timone Children's Hospital. Preauricular fistulas and cystic hygromas were not included. The anomalies in this series were classified as either malformations of the midline or malformations of laterocervical region. Malformations of the midline included the thyroglossal duct cysts (n=102) and dermoid cysts (n=21). The most common malformations of the laterocervical region were cysts and fistulas of the second cleft (n=37) followed by those of the first cleft (n=20),those of the fourth pouch (n=7), and thymic cysts (n=4). Diagnosis of malformations of the midline is usually straightforward. However, diagnosis of malformation of the laterocervical region can be problematic. Misdiagnosis often leads to inadequate treatment with recurrence and functional as well as cosmetic sequelae.

Evaluation of esophageal motor function in clinical practice

Esophageal motor function is highly coordinated between central and enteric nervous systems and the esophageal musculature, which consists of proximal skeletal and distal smooth muscle in three functional regions, the upper and lower esophageal sphincters, and the esophageal body. While upper endoscopy is useful in evaluating for structural disorders of the esophagus, barium esophagography, radionuclide transit studies, and esophageal intraluminal impedance evaluate esophageal transit and partially assess motor function. However, esophageal manometry is the test of choice for the evaluation of esophageal motor function. In recent years, high-resolution manometry (HRM) has streamlined the process of acquisition and display of esophageal pressure data, while uncovering hitherto unrecognized esophageal physiologic mechanisms and pathophysiologic patterns. New algorithms have been devised for analysis and reporting of esophageal pressure topography from HRM. The clinical value of HRM extends to the pediatric population, and complements preoperative evaluation prior to foregut surgery. Provocative maneuvers during HRM may add to the assessment of esophageal motor function. The addition of impedance to HRM provides bolus transit data, but impact on clinical management remains unclear. Emerging techniques such as 3-D HRM and impedance planimetry show promise in the assessment of esophageal sphincter function and esophageal biomechanics.

An alginate-antacid formulation (Gaviscon Double Action Liquid) can eliminate or displace the postprandial 'acid pocket' in symptomatic GERD patients

BACKGROUND

Recently, an 'acid pocket' has been described in the proximal stomach, particularly evident postprandially in GERD patients, when heartburn is common. By creating a low density gel 'raft' that floats on top of gastric contents, alginate-antacid formulations may neutralise the 'acid pocket'.

AIM

To assess the ability of a commercial high-concentration alginate-antacid formulation to neutralize and/or displace the acid pocket in GERD patients.

METHODS

The 'acid pocket' was studied in ten symptomatic GERD patients. Measurements were made using concurrent stepwise pH pull-throughs, high resolution manometry and fluoroscopy in a semi-recumbent posture. Each subject was studied in three conditions: fasted, 20 min after consuming a high-fat meal and 20 min later after a 20 mL oral dose of an alginate-antacid formulation (Gaviscon Double Action Liquid, Reckitt Benckiser Healthcare, Hull, UK). The relative position of pH transition points (pH >4) to the EGJ high-pressure zone was analysed.

RESULTS

Most patients (8/10) exhibited an acidified segment extending from the proximal stomach into the EGJ when fasted that persisted postprandially. Gaviscon neutralised the acidified segment in six of the eight subjects shifting the pH transition point significantly away from the EGJ. The length and pressure of the EGJ high-pressure zone were minimally affected.

CONCLUSIONS

Gaviscon can eliminate or displace the 'acid pocket' in GERD patients. Considering that EGJ length was unchanged throughout, this effect was likely attributable to the alginate 'raft' displacing gastric contents away from the EGJ. These findings suggest the alginate-antacid formulation to be an appropriately targeted postprandial GERD therapy.

Esophagogastric junction morphology is associated with a positive impedance-pH monitoring in patients with GERD

BACKGROUND

High-resolution manometry (HRM) provides information on esophagogastric junction (EGJ) morphology, distinguishing three different subtypes. Data on the correlation between EGJ subtypes and impedance-pH detected reflux patterns are lacking. We aimed to correlate the EGJ subtypes with impedance-pH findings in patients with reflux symptoms.

METHODS

Consecutive patients with suspected gastroesophageal reflux disease (GERD) were enrolled. All patients underwent HRM and impedance-pH testing off-therapy. EGJ was classified as: Type I, no separation between the lower esophageal sphincter (LES) and crural diaphragm (CD); Type II, minimal separation (>1 and <2 cm); Type III, ≥ 2 cm separation. We measured esophageal acid exposure time (AET), number of total reflux episodes and symptom association analysis.

KEY RESULTS

We enrolled 130 consecutive patients and identified 46.2% Type I EGJ, 38.5% Type II, and 15.4% Type III patients. Type III subjects had a higher number of reflux episodes (61 vs 45, p < 0.03, vs 25, p < 0.001), a greater mean AET (12.4 vs 4.2, p < 0.02, vs 1.5, p < 0.001) and a greater positive symptom association (75% vs 72%, p = 0.732 vs 43.3%, p < 0.02) compared with Type II and I patients, respectively. Furthermore, Type II subjects showed statistically significant (overall p < 0.01) increased reflux when compared with Type I patients. Type III and II EGJ morphologies had a more frequent probability to show a positive multichannel intraluminal impedance pH monitoring than Type I (95% vs 84% vs 50%, p < 0.001).

CONCLUSIONS & INFERENCES

Increasing separation between LES and CD can cause a gradual and significant increase in reflux. EGJ morphology may be useful to estimate an abnormal impedance-pH testing in GERD patients.

Esophageal capsule endoscopy versus esophagogastroduodenoscopy for evaluating portal hypertension: a prospective comparative study of performance and tolerance

BACKGROUND AND STUDY AIMS

Esophagogastroduodenoscopy (EGD) is the most effective method for examining the upper gastrointestinal tract, and particularly for evaluating portal hypertension in cirrhotic patients, especially for screening purposes. The aim of this study was to assess the feasibility, safety, accuracy, and tolerance of PillCam ESO capsule endoscopy for this indication.

PATIENTS AND METHODS

In this prospective study, unsedated EGD and capsule endoscopy examinations were conducted on the same day in cirrhotic patients at the time of diagnosis. The patients quantified the tolerability (relative to pain, nausea, choking sensations, etc.) of the two procedures using a 100-mm visual analogue scale. The time required for the recording and for diagnosis with the capsule examination were documented, as were the patients' preferences in comparison with EGD. Two independent endoscopists blinded to the EGD diagnoses assessed the diagnostic accuracy of the images obtained.

RESULTS

Twenty-one patients were included in the study (mean age 62, mean Model for End-Stage Liver Disease score 10.5, mean Child-Pugh score 7.3). The procedure was safe. One patient was unable to swallow the capsule. The mean recording time was 213 s (range 6 - 1200 s); the procedure accurately assessed the presence or absence of esophageal varices in 16 of 19 patients (84.2 %); and it correctly indicated a need for primary prophylaxis (esophageal varices of grade 2 or more and/or red signs) in 100 % of cases. The tolerability of the capsule endoscopy examination was significantly better, and all of the patients preferred capsule endoscopy to EGD (which was transnasal in 11 patients).

CONCLUSIONS

Capsule endoscopy was feasible, safe, accurate, highly acceptable, and preferred by cirrhotic patients undergoing screening for portal hypertension. This new technique requires further and more extensive evaluation, as well as assessment of its cost-effectiveness.

Esophagogastric junction contractility for clinical assessment in patients with GERD: a real added value?

BACKGROUND

The role of esophagogastric junction contractile integral (EGJ-CI) as assessed by high-resolution manometry (HRM) is unclear. We aimed to correlate the EGJ-CI with impedance-pH findings in gastro-esophageal reflux disease (GERD) patients.

METHODS

Consecutive patients with GERD symptoms were enrolled. All patients underwent upper endoscopy, HRM, and impedance-pH testing. The EGJ-CI was calculated using the distal contractile integral tool box during three consecutive respiratory cycles. The value was then divided by the duration of these cycles. A value below 13 was considered as a defective EGJ-CI. We also assessed EGJ morphology, esophageal acid exposure time (AET), number of reflux episodes (NRE), and symptom association analysis (SAA). A positive impedance-pH monitoring was considered in case of abnormal AET and/or NRE and/or positive SAA.

KEY RESULTS

Among 130 patients we enrolled, 91 had GERD (abnormal AET and/or elevated NRE and/or positive SAA) and 39 had functional heartburn (FH) (negative endoscopy, normal AET, normal NRE, and negative SAA). The GERD patients had a lower median value of EGJ-CI (11 [3.1-20.7] vs 22 [9.9-41], p < 0.02) compared to FH patients. Patients with a defective EGJ-CI had, more frequently, a positive impedance-pH monitoring or esophageal mucosal lesions at endoscopy (p < 0.05 and p < 0.05, respectively) than patients with a normal EGJ-CI. An EGJ-CI cut-off value of 5 mmHg cm yielded the optimal performance in identifying GERD at impedance-pH (sensitivity 89%-specificity 63%).

CONCLUSIONS & INFERENCES

A defective EGJ-CI at HRM is clearly associated with evidence of GERD at impedance-pH monitoring. Evaluating EGJ-CI may be useful to predict an abnormal impedance-pH testing.

Tolerance and efficacy of argon plasma coagulation for controlling bleeding in patients with typical and atypical manifestations of watermelon stomach

BACKGROUND AND STUDY AIMS

Watermelon stomach is a well-known cause of gastrointestinal bleeding and anemia. This study investigated the efficacy of and patient tolerance for argon plasma coagulation (APC) in this condition.

PATIENTS AND METHODS

The reports of 21 patients with watermelon stomach who were treated using APC from February 1998 to August 2001 were reviewed. The efficacy of APC was evaluated on the basis of the patients' symptoms, transfusion requirements, and hemoglobin levels.

RESULTS

Fifty-nine APC sessions were carried out (mean 2.81 sessions per patient, range one to five). Depending on the bleeding outcome and lesion intensity, repeat treatments were carried out with a mean delay of 1.8 months (range 2 days - 6 months). The mean follow-up period after the last session was 14.9 months (1 - 60.6 months). All of the patients required repeated blood transfusions before APC, compared with only two patients after treatment. One of these two patients died of uncontrolled bleeding despite APC. The mean hemoglobin level was 80.9 g/l before treatment, compared with 103.2 g/l after treatment. Three patients had recurrent bleeding 4.4 - 31.7 months (mean 13.8 months) after the last session and required a further session of APC, which controlled bleeding in all cases. Complications encountered consisted of two cases of hematemesis and one of sepsis.

CONCLUSIONS

APC was effective in controlling bleeding due to watermelon stomach in the great majority of patients, with a low complication rate.

Pilomatrixoma of the head and neck in children: a study of 38 cases and a review of the literature

OBJECTIVES

To describe the clinical presentations and discuss the guidelines for surgical management of pilomatrixoma involving the head and neck in children.

DESIGN

Retrospective study.

SETTING

A tertiary care center.

PATIENTS

Thirty-three patients, with a mean age of 4.5 years, underwent surgical treatment for pilomatrixoma (n = 38) between 1989 and 1997.

INTERVENTION

All patients were treated surgically. In 34 cases, a direct approach was used to achieve complete removal of the lesion with (n = 11) or without (n = 23) skin resection. In the remaining 4 cases, an indirect approach via a parotidectomylike incision was used.

RESULTS

In 88% of cases, the presenting symptom was a hard, slow-growing, subcutaneous tumor. The lesion was associated with pain and inflammation in 7 cases (18%) and abscess or ulceration in 4 cases (11%). Twenty-nine patients presented with single nodules and 4 presented with multiple occurrences. The lesions were located on the face (cheek, eyelid, or forehead) in 20 cases (53%), on the neck in 8 cases (21%), in the parotid region in 8 cases (21%), and on the scalp in 2 cases (5%).

CONCLUSIONS

Pilomatrixoma is a rare, benign skin tumor, but practitioners should be aware of its clinical features. Diagnosis is usually easy based on clinical findings, but computed tomographic scan is helpful, especially in cases involving tumors located in the parotid region. Spontaneous regression is never observed. Complete surgical excision, including the overlying skin, is the treatment of choice.

Ambulatory 24-h oesophageal impedance-pH recordings: reliability of automatic analysis for gastro-oesophageal reflux assessment

Oesophageal pH-impedance monitoring allows detection of acid and non-acid gastro-oesophageal reflux (GOR) events. Visual analysis of impedance recording requires expertise. Our aim was to evaluate the efficacy of an automated analysis for GOR assessment. Seventy-three patients with suspected GORD underwent 24-h oesophageal pH-impedance monitoring. Recordings analysis was performed visually (V) and automatically using Autoscan function (AS) of Bioview software. A symptom index (SI) > or =50% was considered for a significant association between symptoms and reflux events. AS analysis detected more reflux events, especially non-acid, liquid, pure gas and proximal events. Detection of oesophageal acid exposure and acid reflux events was similar with both analyses. Agreement between V and AS analysis was good (Kendall's coefficient W > 0.750, P < 0.01) for all parameters. During pH-impedance studies, 65 patients reported symptoms. As compared to visual analysis, the sensitivity and specificity of a positive SI determined by AS were respectively 85.7% and 80% for all reflux events, 100% and 98% for acid reflux and 33% and 87.5% for non-acid reflux. Despite good agreement with visual analysis, automatic analysis overestimates the number of non-acid reflux events. Visual analysis remains the gold standard to detect an association between symptoms and non-acid reflux events.

Randomised clinical trial: effects of monotherapy with ADX10059, a mGluR5 inhibitor, on symptoms and reflux events in patients with gastro-oesophageal reflux disease

BACKGROUND

ADX10059, a metabotropic glutamate receptor 5 (mGluR5) negative allosteric modulator, has been shown to reduce gastro-oesophageal reflux events and oesophageal acid exposure in patients with gastro-oesophageal reflux disease (GERD) and healthy subjects.

AIM

  To evaluate the effects of ADX10059 monotherapy for 2 weeks on symptom control in patients with GERD.

METHODS

This was a double-blind, placebo-controlled, multi-centre trial in GERD patients who were responders to proton pump inhibitors (PPIs). Following PPIs withdrawal, a 2-week baseline washout period was followed by 2-week treatment with either ADX10059 120 mg or placebo b.d. The primary clinical efficacy endpoint was the number of GERD symptom-free days in treatment week 2 compared with the last 7 days of baseline. The effect on reflux events using 24-h impedance-pH monitoring was also determined in a subset of 24 patients.

RESULTS

The full analysis set comprised 103 patients ADX10059 (N= 50), Placebo (N=53). In treatment week 2, ADX10059 significantly increased GERD symptom-free days (P=0.045) and heartburn-free days (P=0.037), reduced antacid use (P=0.017), improved total symptom score (P=0.048) including subscale heartburn/regurgitation (P=0.007) and sleep disturbance because of GERD (P= 0.022). ADX10059 significantly reduced total (P=0.034) and acidic reflux events (P=0.003). ADX10059 was well tolerated. Most common adverse events for ADX10059 were mild to moderate dizziness 16% and vertigo 12% (placebo 4% and 2%).

CONCLUSIONS

Inhibition of mGluR5 with ADX10059 monotherapy reduces reflux events and improves symptoms in GERD patients. This mechanism has promise for the management of GERD.

Normative values in esophageal high-resolution manometry

BACKGROUND

Esophageal high-resolution manometry (HRM) has rapidly gained much popularity worldwide. The Chicago Classification for esophageal motility disorders is based on a set of normative values for key metrics that was obtained using one of the commercially available HRM systems. Thus, it is of great importance to evaluate whether these normative values can be used for other HRM systems as well.

PURPOSE

In this review, we describe the presently available HRM systems, the currently known normative thresholds and the factors that influence them, and assess the use of these thresholds. Numerous factors including the type of HRM system, demographic factors, catheter diameter, body position during testing, consistency of bolus swallows, and esophageal length have an influence on the normative data. It would thus be ideal to have different sets of normal values for each of these factors, yet at the moment the amount of normative data is limited. We suggest broadening the normal range for parameters, as this would allow abnormal values to be of more significance. In addition, we suggest conducting studies to assess the physiological relevance of abnormal values and stress that for each system different normative thresholds may apply.

The Pathogenesis and Management of Achalasia: Current Status and Future Directions

Achalasia is an esophageal motility disorder that is commonly misdiagnosed initially as gastroesophageal reflux disease. Patients with achalasia often complain of dysphagia with solids and liquids but may focus on regurgitation as the primary symptom, leading to initial misdiagnosis. Diagnostic tests for achalasia include esophageal motility testing, esophagogastroduodenoscopy and barium swallow. These tests play a complimentary role in establishing the diagnosis of suspected achalasia. High-resolution manometry has now identified three subtypes of achalasia, with therapeutic implications. Pneumatic dilation and surgical myotomy are the only definitive treatment options for patients with achalasia who can undergo surgery. Botulinum toxin injection into the lower esophageal sphincter should be reserved for those who cannot undergo definitive therapy. Close follow-up is paramount because many patients will have a recurrence of symptoms and require repeat treatment.

Validation of criteria for the definition of transient lower esophageal sphincter relaxations using high-resolution manometry

BACKGROUND

Criteria for transient lower esophageal sphincter relaxations (TLESRs) are well-defined for Dentsleeve manometry. As high-resolution manometry (HRM) is now the gold standard to assess esophageal motility, our aim was to propose a consensus definition of TLESRs using HRM.

METHODS

Postprandial esophageal HRM combined with impedance was performed in 10 patients with gastroesophageal reflux disease. Transient lower esophageal sphincter relaxations identification was performed by 17 experts using a Delphi process. Four investigators then characterized TLESR candidates that achieved 100% agreement (TLESR events) and those that achieved less than 25% agreement (non-events) after the third round. Logistic regression and decision tree analysis were used to define optimal diagnostic criteria.

KEY RESULTS

All diagnostic criteria were more frequently encountered in the 57 TLESR events than in the 52 non-events. Crural diaphragm (CD) inhibition and LES relaxation duration >10 seconds had the highest predictive value to identify TLESR. Based on decision tree analysis, reflux on impedance, esophageal shortening, common cavity, upper esophageal sphincter relaxation without swallow and secondary peristalsis were alternate diagnostic criteria.

CONCLUSION & INFERENCES

Using HRM, TLESR might be defined as LES relaxation occurring in absence of swallowing, lasting more than 10 seconds and associated with CD inhibition.

Vigor of peristalsis during multiple rapid swallows is inversely correlated with acid exposure time in patients with NERD

BACKGROUND

Multiple rapid swallowing (MRS) during high-resolution manometry (HRM) is increasingly utilized as provocative test to assess esophageal peristaltic reserve. The aim of this study was to evaluate the correlation between MRS response and impedance and pH (MII-pH) parameters in endoscopy negative heartburn (ENH) patients.

METHODS

We enrolled consecutive ENH patients, who underwent HRM and MII-pH study, with a selected MII-pH profile: abnormal MII-pH (pH+/MII+); normal MII-pH (pH-/MII-). HRM was performed with 10 wet swallows (WS) and one MRS. Mean distal contractile integral (DCI) during WS and MRS were calculated. MII-pH parameters including acid exposure time (AET), reflux events, baseline impedance levels (BI) and the efficacy of chemical clearance evaluated with the postreflux swallow-induced peristaltic wave (PSPW) index were measured.

KEY RESULTS

We analyzed 103 patients: 49 MII+/pH+ (27 male), and 54 MII-/pH- (19 male). Mean age was similar between the two groups. As expected, mean AET and number of refluxes were higher in pH+/MII+ (p < 0.05). HRM was normal in all selected patients. Mean DCI-WS was similar between two groups (p = n.s.). Mean DCI-MRS- was higher in MII-/pH- vs MII+/pH+ (p < 0.05). The increase in DCI-MRS was inversely correlated with AET (-0.699; p < 0.001) and directly correlated with BI values (0.631; p < 0.001) and PSPW index (0.626; p < 0.001).

CONCLUSIONS & INFERENCES

Following MRS, patients with abnormal impedance-pH test showed suboptimal contraction response as compared with those with normal impedance-pH test. Moreover, MRS response was inversely correlated with AET and directly correlated with BI values and PSPW index.

Randomized clinical trial of sacral nerve stimulation for refractory constipation

Background

Open studies have reported favourable results for sacral nerve stimulation in the treatment of refractory constipation. Here, its efficacy was assessed in a double-blind crossover RCT.

Methods

Patients with at least two of the following criteria were included: fewer than three bowel movements per week; straining to evacuate on more than 25 per cent of attempts; or sensation of incomplete evacuation on more than 25 per cent of occasions. Response to therapy was defined as at least three bowel movements per week and/or more than 50 per cent improvement in symptoms. Responders to an initial 3-week peripheral nerve evaluation were offered permanent implantation of a pulse generator and were assigned randomly in a crossover design to two 8-week intervals of active or sham stimulation. At the end of the two trial periods, the patients received active stimulation until the final evaluation at 1 year.

Results

Thirty-six patients (34 women; mean(s.d.) age 45(14) years) underwent peripheral nerve evaluation. Twenty responded and received a permanent stimulator. A positive response was observed in 12 of 20 and 11 of 20 patients after active and sham stimulation periods respectively (P = 0·746). Pain related to the device occurred in five patients and wound infection or haematoma in three, leading to definitive removal of the pulse generator in two patients. At 1 year, 11 of the 20 patients with an implanted device continued to respond. Stimulation had no significant effect on colonic transit time.

Conclusion

These results do not support the recommendation of permanent implantation of a pulse generator in patients with refractory constipation who initially responded to temporary nerve stimulation. Registration number: NCT01629303 (http://www.clinicaltrials.gov).

Mouse smad8 phosphorylation downstream of BMP receptors ALK-2, ALK-3, and ALK-6 induces its association with Smad4 and transcriptional activity

Smads are intracellular signaling mediators for TGF-beta superfamily. Smad1 and Smad5 are activated by BMP receptors. Here, we have cloned mouse Smad8 and functionally characterized its ability to transduce signals from BMP receptors. Constitutively active BMP type I receptors, ALK-3 and ALK-6, as well as ALK-2, were phosphorylated Smad8 and induced Smad8 interaction with Smad4. Nuclear translocation of Smad8 was stimulated by constitutively active BMP type I receptors. In contrast, constitutively active TGF-beta type I receptor, ALK-5, did not exhibit any action on Smad8. Smad8 and Smad4 cooperatively induced the promoter of Xvent2, a homeobox gene that responds specifically to BMP signaling. Dominant-negative Smad8 was shown to inhibit the increase of alkaline phosphatase activity induced by BMP-2 on pluripotent mesenchymal C3H10T1/2 and myoblastic C2C12 cell lines. The presence of Smad8 mRNA in mouse calvaria cells and osteoblasts suggests a role of Smad8 in the osteoblast differentiation and maturation.

Identification of regions of the P2X(7) receptor that contribute to human and rat species differences in antagonist effects

BACKGROUND AND PURPOSE

Several P2X(7) receptor antagonists are allosteric inhibitors and exhibit species difference in potency. Furthermore, N(2)-(3,4-difluorophenyl)-N(1)-(2-methyl-5-(1-piperazinylmethyl)phenyl)glycinamide dihydrochloride (GW791343) exhibits negative allosteric effects at the human P2X(7) receptor but is a positive allosteric modulator of the rat P2X(7) receptor. In this study we have identified several regions of the P2X(7) receptor that contribute to the species differences in antagonist effects.

EXPERIMENTAL APPROACH

Chimeric human-rat P2X(7) receptors were constructed with regions of the rat receptor being inserted into the human receptor. Antagonist effects at these receptors were measured in ethidium accumulation and radioligand binding studies.

KEY RESULTS

Exchanging regions of the P2X(7) receptor close to transmembrane domain 1 modified the effects of KN62, 4-(4-fluorophenyl)-2-(4-methylsulphinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580) and GW791343. Further studies, in which single amino acids were exchanged, identified amino acid 95 as being primarily responsible for the differential allosteric effects of GW791343 and, to varying degrees, the species differences in potency of SB203580 and KN62. The species selectivity of pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid was affected by multiple regions of the receptor, with potency being particularly affected by the amino acid 126 but not by amino acid 95. A further region of the rat receptor (amino acids 154-183) was identified that, when inserted into the corresponding position in the human receptor, increased ATP potency 10-fold.

CONCLUSIONS

This study has identified several key residues responsible for the species differences in antagonist effects at the P2X(7) receptor and also identified a further region of the P2X(7) receptor that can significantly affect agonist potency at the P2X(7) receptor.