Human nuclear hormone receptor activity contributes to malaria parasite liver stage development.

Chemical genetic approaches have had a transformative impact on discovery of drug targets for malaria but have primarily been used for parasite targets. To identify human pathways required for intrahepatic development of parasite, we implemented multiplex cytological profiling of malaria infected hepatocytes treated with liver stage active compounds. Some compounds, including MMV1088447 and MMV1346624, exhibited profiles similar to cells treated with nuclear hormone receptor (NHR) agonist/antagonists. siRNAs targeting human NHRs, or their signaling partners identified eight genes that were critical for Plasmodium berghei infection. Knockdown of NR1D2, a host NHR, significantly impaired parasite growth by downregulation of host lipid metabolism. Importantly, treatment with MMV1088447 and MMV1346624 but not other antimalarials, phenocopied the lipid metabolism defect of NR1D2 knockdown. Our data underlines the use of high-content imaging for host-cellular pathway deconvolution, highlights host lipid metabolism as a drug-able human pathway and provides new chemical biology tools for studying host-parasite interactions.

Enhanced copper removal from contaminated kaolinite soil by electrokinetic process using compost reactive filter media.

Electrokinetic (EK) remediation is a promising technology for soil decontamination, although basic pH in the soil close to cathode has constrained EK effectiveness due to heavy metal precipitation. This study aimed to enhance copper removal from kaolinite soil by integrating EK with compost (C) as recyclable reactive filter media (RFM) for the first time. Compost placed near the cathode served as an adsorbent to bind copper ions while buffering the advancement of the alkaline front in soil. The total copper removal rate increased from 1.03% in EK to 45.65% in EK-100%C under an electric potential of 10 V. Further experiments conducted by using biochar (BC) and compost/biochar (C + BC) mixture RFM at different ratios showed total Cu removal efficiency decreasing as EK-100%C > EK-(10%BC + 90%C) > EK-(20%BC + 80%C) > EK-(30%BC + 70%C) > EK. The application of a constant electric current of 20.00 mA further enhanced copper removal to 84.09% in EK-100%C although did not show significant enhancement in EK-(BC + C). The compost RFM was regenerated by acid extraction and then reused twice, achieving a total removal of 74.11%. The findings demonstrated compost as a promising and reusable RFM for the efficient removal of copper in contaminated soil.

Copper removal from contaminated soil through electrokinetic process with reactive filter media.

Electrokinetic (EK) remediation has been used in the removal of metal ions from contaminated soil. This study focused on integrating the EK technique with different reactive filter media (RFM) of activated carbon (AC) and biochar (BC) for the first time without adding chemicals to facilitate the removal of copper ions from the contaminated kaolinite soil. Tests based on EK, EK coupled with AC (EK-AC), and EK combined with BC (EK-BC) were performed under an electric potential of 10 V, and the overall removal efficiency of copper ions decreased as EK-BC > EK-AC > EK. The results show that 27% of copper in the soil was captured by BC, compared with only 10% by AC. Additional EK-BC test performed under a constant current (20 mA) revealed that the acid front swept across the soil, resulting in 70.6-95.0% copper removal from soil sections 4 to 1 close to the anode region with more copper accumulation in section 5. Similar to the EK-BC test under a fixed voltage, 26% of copper in the soil was captured by BC during EK-BC treatment under a constant current although with a higher energy consumption. Moreover, RFM was regenerated by flushing with an acid solution, achieving 99.3% of copper recovery in BC and 78.4% in AC. Although the permeability of AC-RFM was higher than that of BC-RFM, copper contaminant was more easily leached out from the BC-RFM. The findings demonstrated the feasibility of contaminant entrapment in BC-RFM and recovery by acid leaching, with potential for sustainable soil remediation.

Randomised clinical trial: Bifidobacterium lactis NCC2818 probiotic vs placebo, and impact on gut transit time, symptoms, and gut microbiology in chronic constipation.

BACKGROUND: Constipation is a prevalent gastrointestinal disorder. Patient dissatisfaction with prescribed medications is common, and there is need for alternative management strategies. Evidence shows that Bifidobacterium species may be beneficial in constipation. AIM: To investigate changes in physiological and clinical measures of gut function in patients with chronic constipation following the consumption of Bifidobacterium lactis NCC2818, compared to placebo. METHODS: Participants were randomised to a 4-week supplementation with B. lactis NCC2818 (1.5 x 1010 CFU/d) or placebo. Gut transit time was measured using a radio-opaque marker, while symptoms and quality of life were assessed using validated questionnaires. Gut microbiota composition was assessed using quantitative polymerase chain reaction. Analysis of covariance was used for normally distributed variables, and Mann-Whitney test for non-normally distributed variables. RESULTS: Seventy-five participants were randomised. There was no significant difference between the probiotic and placebo groups in gut transit time change from baseline to week 2 (-11.7 hours, SD 33.0 hours vs -12.9 hours, SD 33.6 hours; P = 0.863) or to week 4 (-20.4 hours, SD 32.5 h vs -8.7 hours, SD 33.8 hours; P = 0.103). There were also no improvements in stool output, symptoms, or quality of life. No differences were found in Bifidobacterium concentrations between the probiotic and placebo groups at week 4 (9.5 log10 /g dry faeces, SD 0.3 vs 9.4 log10 /g, SD 1.0; P = 0.509). CONCLUSIONS: Bifidobacterium lactis NCC2818 was not effective in the management of mild chronic constipation. This study highlights the importance of further studies and their publication to better understand the strain-specific effects of probiotics.

Protease-activated receptor-2 in endosomes signals persistent pain of irritable bowel syndrome.

Once activated at the surface of cells, G protein-coupled receptors (GPCRs) redistribute to endosomes, where they can continue to signal. Whether GPCRs in endosomes generate signals that contribute to human disease is unknown. We evaluated endosomal signaling of protease-activated receptor-2 (PAR2), which has been proposed to mediate pain in patients with irritable bowel syndrome (IBS). Trypsin, elastase, and cathepsin S, which are activated in the colonic mucosa of patients with IBS and in experimental animals with colitis, caused persistent PAR2-dependent hyperexcitability of nociceptors, sensitization of colonic afferent neurons to mechanical stimuli, and somatic mechanical allodynia. Inhibitors of clathrin- and dynamin-dependent endocytosis and of mitogen-activated protein kinase kinase-1 prevented trypsin-induced hyperexcitability, sensitization, and allodynia. However, they did not affect elastase- or cathepsin S-induced hyperexcitability, sensitization, or allodynia. Trypsin stimulated endocytosis of PAR2, which signaled from endosomes to activate extracellular signal-regulated kinase. Elastase and cathepsin S did not stimulate endocytosis of PAR2, which signaled from the plasma membrane to activate adenylyl cyclase. Biopsies of colonic mucosa from IBS patients released proteases that induced persistent PAR2-dependent hyperexcitability of nociceptors, and PAR2 association with ß-arrestins, which mediate endocytosis. Conjugation to cholestanol promoted delivery and retention of antagonists in endosomes containing PAR2 A cholestanol-conjugated PAR2 antagonist prevented persistent trypsin- and IBS protease-induced hyperexcitability of nociceptors. The results reveal that PAR2 signaling from endosomes underlies the persistent hyperexcitability of nociceptors that mediates chronic pain of IBS. Endosomally targeted PAR2 antagonists are potential therapies for IBS pain. GPCRs in endosomes transmit signals that contribute to human diseases.

Short-Term Daily Intake of Polydextrose Fiber Does Not Shorten Intestinal Transit Time in Constipated Adults: A Randomized Controlled Trial.

Chronic constipation (CC) remains a common gastrointestinal (GI) disorder that conveys a substantial healthcare burden. Expert guidelines recommend increasing fiber intake, yet the clinical evidence to support this needs strengthening for specific fibers. The aim was to evaluate changes in intestinal transit time and GI symptoms in CC patients who consumed polydextrose. In a randomized, double-blind, placebo-controlled trial, 128 adults with CC received 8 g or 12 g polydextrose, or placebo, daily for 4 weeks. Transit time, as primary outcome, was assessed by radiopaque marker distribution after 2-weeks intervention. Bowel habits, GI symptoms and quality of life (QOL) were assessed by questionnaire, including the Patient-Assessment of Constipation (PAC) Symptoms (SYM), and PAC-QOL. Following 2-weeks intervention, no reduction was seen in transit time in any group and following 2- or 4-weeks intervention, no improvements were seen in stool frequency or consistency in any group. After 2-weeks intervention with 8 g/day polydextrose an improvement was seen in the PAC-SYM rectal score (p = 0.041). After 4-weeks intervention both rectal (p = 0.049) and stool (p = 0.029) scores improved while improvement in the QOL satisfaction score did not reach significance (p = 0.071). Overall, the results suggest that 2-weeks consumption of 8 or 12 g/day polydextrose does not significantly improve physiological measures of gut function in CC adults. Longer term consumption may improve clinical measures, but further studies will be required to substantiate this.

Predictability of European 2016/2017.

Winter 2016/2017 was one of the driest on record for central Europe and the United Kingdom. This was the result of blocked atmospheric circulation with high pressure centred over North-West Europe dominating the winter mean circulation pattern. Using large ensembles of simulated winters, we find that the observed winter 2016/2017 circulation was very similar in pattern and strength to the circulation associated with the top 10% of driest Central European winters. Here, we explore whether seasonal forecasts were able to predict this circulation pattern. Despite the fact that the observed circulation anomaly did not project on to the North Atlantic Oscillation (NAO), we find that forecasts starting in November did predict a high-pressure anomaly over North-Western Europe. We use two independent data sets, and methods, to probe the drivers of this circulation pattern. We find evidence for a Rossby Wave propagating out of the tropical Atlantic where there were anomalous local rainfall anomalies. This case study is another example of real-time seasonal forecast skill for Europe and provides evidence for predictability beyond the NAO pattern.

Endosomal signaling of the receptor for calcitonin gene-related peptide mediates pain transmission.

G protein-coupled receptors (GPCRs) are considered to function primarily at the plasma membrane, where they interact with extracellular ligands and couple to G proteins that transmit intracellular signals. Consequently, therapeutic drugs are designed to target GPCRs at the plasma membrane. Activated GPCRs undergo clathrin-dependent endocytosis. Whether GPCRs in endosomes control pathophysiological processes in vivo and are therapeutic targets remains uncertain. We investigated the contribution of endosomal signaling of the calcitonin receptor-like receptor (CLR) to pain transmission. Calcitonin gene-related peptide (CGRP) stimulated CLR endocytosis and activated protein kinase C (PKC) in the cytosol and extracellular signal regulated kinase (ERK) in the cytosol and nucleus. Inhibitors of clathrin and dynamin prevented CLR endocytosis and activation of cytosolic PKC and nuclear ERK, which derive from endosomal CLR. A cholestanol-conjugated antagonist, CGRP8-37, accumulated in CLR-containing endosomes and selectively inhibited CLR signaling in endosomes. CGRP caused sustained excitation of neurons in slices of rat spinal cord. Inhibitors of dynamin, ERK, and PKC suppressed persistent neuronal excitation. CGRP8-37-cholestanol, but not unconjugated CGRP8-37, prevented sustained neuronal excitation. When injected intrathecally to mice, CGRP8-37-cholestanol inhibited nociceptive responses to intraplantar injection of capsaicin, formalin, or complete Freund's adjuvant more effectively than unconjugated CGRP8-37 Our results show that CLR signals from endosomes to control pain transmission and identify CLR in endosomes as a therapeutic target for pain. Thus, GPCRs function not only at the plasma membrane but also in endosomes to control complex processes in vivo. Endosomal GPCRs are a drug target that deserve further attention.

Transplantation of fecal microbiota from patients with irritable bowel syndrome alters gut function and behavior in recipient mice.

Irritable bowel syndrome (IBS) is a common disorder characterized by altered gut function and often is accompanied by comorbid anxiety. Although changes in the gut microbiota have been documented, their relevance to the clinical expression of IBS is unknown. To evaluate a functional role for commensal gut bacteria in IBS, we colonized germ-free mice with the fecal microbiota from healthy control individuals or IBS patients with diarrhea (IBS-D), with or without anxiety, and monitored gut function and behavior in the transplanted mice. Microbiota profiles in recipient mice clustered according to the microbiota profiles of the human donors. Mice receiving the IBS-D fecal microbiota showed a taxonomically similar microbial composition to that of mice receiving the healthy control fecal microbiota. However, IBS-D mice showed different serum metabolomic profiles. Mice receiving the IBS-D fecal microbiota, but not the healthy control fecal microbiota, exhibited faster gastrointestinal transit, intestinal barrier dysfunction, innate immune activation, and anxiety-like behavior. These results indicate the potential of the gut microbiota to contribute to both intestinal and behavioral manifestations of IBS-D and suggest the potential value of microbiota-directed therapies in IBS patients.

Bridging the divide: illuminating the path of intercellular exchange through ring canals.

Ring canals are made from arrested cleavage furrows, and provide direct cytoplasmic connections among sibling cells. They are well documented for their participation in Drosophila oogenesis, but little is known about their role in several somatic tissues in which they are also found. Using a variety of genetic tools in live and fixed tissue, we recently demonstrated that rapid intercellular exchange occurs through somatic ring canals by diffusion, and presented evidence that ring canals permit equilibration of protein among transcriptionally mosaic cells. We also used a novel combination of markers to evaluate the extent of protein movement within and across mitotic clones in follicle cells and imaginal discs, providing evidence of robust movement of GFP between the 2 sides of mitotic clones and frequently into non-recombined cells. These data suggest that, depending on the experimental setup and proteins of interest, inter-clonal diffusion of protein may alter the interpretation of clonal data in follicle cells. Here, we discuss these results and provide additional insight into the impact of ring canals in Drosophila somatic tissues.

Protein equilibration through somatic ring canals in Drosophila.

Although intercellular bridges resulting from incomplete cytokinesis were discovered in somatic Drosophila tissues decades ago, the impact of these structures on intercellular communication and tissue biology is largely unknown. In this work, we demonstrate that the ~250-nanometer-diameter somatic ring canals permit diffusion of cytoplasmic contents between connected cells and across mitotic clone boundaries and enable the equilibration of protein between transcriptionally mosaic follicle cells in the Drosophila ovary. We obtained similar, although more restricted, results in the larval imaginal discs. Our work illustrates the lack of cytoplasmic autonomy in these tissues and suggests a role for somatic ring canals in promoting homogeneous protein expression within the tissue.

Intercellular protein movement in syncytial Drosophila follicle cells.

Ring canals connecting Drosophila germline, follicle and imaginal disc cells provide direct contact of cytoplasm between cells. To date, little is known about the formation, structure, or function of the somatic ring canals present in follicle and imaginal disc cells. Here, we show by confocal and electron microscopy that Pavarotti kinesin-like protein and Visgun are stable components of somatic ring canals. Using live-cell confocal microscopy, we show that somatic ring canals form from the stabilization of mitotic cleavage furrows. In contrast to germline cells, syncytial follicle cells do not divide synchronously, are not maximally branched and their ring canals do not increase in size during egg chamber development. We show for the first time that somatic ring canals permit exchange of cytoplasmic proteins between follicle cells. These results provide insight into the composition and function of ring canals in somatic cells, implying a broader functional significance for syncytial organization of cells outside the germline.

Mechanisms of symptom reduction in treatment for obsessions.

OBJECTIVE: We explored the dynamic relationship between cognition and obsession severity during 2 different treatments for primary obsessions, examining evidence for the hypothesis that symptom reduction would be mediated by appraisals about the meaning of unwanted intrusive thoughts. METHOD: Data from a recent randomized controlled trial were analyzed with traditional mediation analyses and latent difference scores. The trial had compared cognitive behavioral therapy and stress management training among 73 patients with primary obsessions. Mediation analyses were conducted with pre-, post-, and follow-up scores on the Obsessions subscale of the Yale-Brown Obsessive Compulsive Scale and 2 self-report measures of cognitions related to obsessive-compulsive disorder. Bivariate dual change score (BDCS) analyses were conducted with weekly assessments of obsession severity and appraisals of personal significance. RESULTS: Change in most cognitions related to obsessive-compulsive disorder accounted for reduction in obsession severity during the course of treatment and follow-up. BDCS analyses of the longitudinal data, however, indicated prior obsession severity is a leading indicator of subsequent change in appraisals, rather than the reverse. Analyses also suggested cognitive behavioral therapy is more effective than stress management training when symptoms are severe and that stress management training is more advantageous in the context of mild-to-moderate obsessions. CONCLUSIONS: The traditional mediation analysis indicated that appraisal change is a tenable mediator of obsession reduction, but the BDCS results raise doubts about the causal direction. The results highlight the importance of examining the dynamic relationship between putative mediators and outcome variables, and they suggest interesting hypotheses about mechanisms in treatment of obsessions.

Technical Advance: Function and efficacy of an {alpha}4-integrin antagonist using bioluminescence imaging to detect leukocyte trafficking in murine experimental colitis.

Leukocyte trafficking is a therapeutic target in IBD. The integrins α4ß and α4ß1 regulate leukocyte migration into tissues and lymphoid organs. Current strategies rely on biologics, such as mAb, to inhibit leukocyte recruitment. Here we show the in vivo therapeutic effects of a small molecule α4-integrin antagonist (GSK223618A) in a leukocyte-trafficking model and a murine model of colitis. Leukocytes isolated from MLNs of transgenic ß-actin-luc+ mice were injected i.v. into recipients with DSS-induced colitis. Recipient mice were orally gavaged with vehicle or an α4-integrin antagonist 1 h pre-adoptive transfer, followed by bioluminescence whole body and ex vivo organ imaging 4 h post-transfer. To confirm its therapeutic effect, the α4-integrin antagonist was given orally twice daily for 6 days to mice with DSS-induced colitis, starting on Day 3. Clinical, macroscopic, and histological signs of inflammation were assessed and gene-expression profiles analyzed. Using bioluminescence imaging, we tracked and quantified leukocyte migration to the inflamed gut and demonstrated its inhibition by a small molecule α4-integrin antagonist. Additionally, the therapeutic effect of the antagonist was confirmed in DSS-induced colitis in terms of clinical, macroscopic, and histological signs of inflammation. Gene expression analysis suggested enhancement of tissue healing in compound-treated animals. Inhibition of leukocyte trafficking using small molecule integrin antagonists is a promising alternative to large molecule biologics. Furthermore, in vivo bioluminescence imaging is a valuable strategy for preclinical evaluation of potential therapeutics that target leukocyte trafficking in inflammatory diseases.

Treatment of obsessions: a randomized controlled trial.

This study tested Rachman's cognitive behavioral method for treating obsessions not accompanied by prominent overt compulsions. The cognitive behavioral treatment was compared to waitlist control and an active and credible comparison of stress management training (SMT). Of the 73 adults who were randomized, 67 completed treatment, and 58 were available for one-year follow-up. The active treatments, compared to waitlist, resulted in substantially lower YBOCS scores, OCD-related cognitions and depression as well as improved social functioning. Overall, CBT and SMT showed large and similar reductions in symptoms. Pre-post effect sizes on YBOCS Obsessions for CBT and SMT completers was d = 2.34 and 1.90, respectively. Although CBT showed small advantages over SMT on some symptom measures immediately after treatment, these differences were no longer apparent in the follow-up period. CBT resulted in larger changes on most OCD-related cognitions compared to SMT. The cognitive changes were stable at 12 months follow-up, but the differences in the cognitive measures faded. The robust and enduring effects of both treatments contradict the long-standing belief that obsessions are resistant to treatment.

Targeting gut T cell Ca2+ release-activated Ca2+ channels inhibits T cell cytokine production and T-box transcription factor T-bet in inflammatory bowel disease.

Prolonged Ca(2+) entry through Ca(2+) release-activated Ca(2+) (CRAC) channels is crucial in activating the Ca(2+)-sensitive transcription factor NFAT, which is responsible for directing T cell proliferation and cytokine gene expression. To establish whether targeting CRAC might counteract intestinal inflammation, we evaluated the in vitro effect of a selective CRAC inhibitor on T cell cytokine production and T-bet expression by lamina propria mononuclear cells (LPMC) and biopsy specimens from inflammatory bowel disease (IBD) patients. The inhibitory activity of the CRAC blocker was investigated through patch-clamp experiments on rat basophilic leukemia cells and fluorometric imaging plate reader intracellular Ca(2+) assays using thapsigargin-stimulated Jurkat T cells and its detailed selectivity profile defined using a range of in vitro radioligand binding and functional assays. Anti-CD3/CD28-stimulated LPMC and biopsy specimens from 51 patients with IBD were cultured with a range of CRAC inhibitor concentrations (0.01-10 microM). IFN-gamma, IL-2, IL-8, and IL-17 were analyzed by ELISA. T-bet was determined by immunoblotting. We found that the CRAC blocker concentration-dependently inhibited CRAC current in rat basophilic leukemia cells and thapsigargin-induced Ca(2+) influx in Jurkat T cells. A concentration-dependent reduction in T-bet expression and production of IFN-gamma, IL-2, IL-17, but not IL-8, was observed in IBD LPMC and biopsy specimens treated with the CRAC inhibitor. In conclusion, we provide evidence that the suppression of CRAC channel function may dampen the increased T cell response in the inflamed gut, thus suggesting a promising role for CRAC inhibitor drugs in the therapeutic management of patients with IBD.

Characterization of a calcitonin gene-related peptide release assay in rat isolated distal colon.

The release of calcitonin gene-related peptide (CGRP) plays a key role gastrointestinal tract homeostasis. We aimed to investigate mechanisms that mediate CGRP release from the rat colon in vitro. Colon segments were stimulated and the amount of CGRP released was measured using an enzyme immunoassay. Capsaicin and low pH induced significant increases in CGRP release which was shown to be mediated by TRPV1 activation as demonstrated with the TRPV1 antagonists CTPC and capsazepine. The mast cell degranulator, compound 48/80 significantly increased CGRP release an effect that was blocked in the presence of the mast cell stabilizer, ketotifen and the selective Gi inhibitor benzalkonium chloride. The addition of a mixture of inflammatory mediators containing pro-inflammatory cytokines, 5HT, bradykinin and PGE2 showed no effect at neutral pH but at low pH a significant additive effect was observed. We conclude that CGRP release in the rat distal colon occurs in response to mast cell degranulation, inflammatory mediators, low pH and capsaicin and describe a role for TRPV1 receptors in mediating the response.

Group and individual treatment of obsessive-compulsive disorder using cognitive therapy and exposure plus response prevention: a 2-year follow-up of two randomized trials.

Relatively little is known about the long-term durability of group treatments for obsessive-compulsive disorder (OCD) and contemporary cognitive treatments. The current study investigated the 2-year follow-up results for participants who completed randomized trials of group or individual treatment and received either cognitive therapy (CT) or exposure plus response prevention (ERP). Yale-Brown Obsessive Compulsive Scale (YBOCS) scores for individual ERP and CT were not significantly different over 2 years. However, YBOCS scores were consistently lower over time for group ERP participants than for group CT participants. With a single exception in the group treatment study, secondary cognitive and depression scores were stable, indicating that gains achieved during acute treatment were maintained over 2 years. Less than 10% of treatment completers relapsed in each of the treatment trials. Approximately 50% of the completer sample was rated as recovered at 2 years. Additionally, a tentative cross-study comparison suggests that CT was better tolerated and resulted in less dropout than did ERP. Despite the overall positive results, efficacy of OCD treatments has reached a plateau and may require a fresh perspective to move forward.

Bravo capsule system optimizes intragastric pH monitoring over prolonged time: effects of ghrelin on gastric acid and hormone secretion in the rat.

AIM: To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time. METHODS: A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutive days. For comparison, a gastric fistula model was used. Effects of ghrelin and esomeprazole, with or without pentagastrin, on gastric pH were studied. In addition, effects of esomeprazole on plasma ghrelin, gastrin and somatostatin were analyzed. RESULTS: All rats recovered after surgery. The average 24-h pH during free feeding was 2.3 +/- 0.1 (n = 20) with a variation of 18% +/- 6% over 5 d. Ghrelin, 2400 pmol/kg, t.i.d. increased pH from 1.7 +/- 0.1 to 3.1 +/- 0.3 (P < 0.01) as recorded with the Bravo system. After esomeprazole (1 mg/kg, 3 mg/kg and 5 mg/kg) there was a dose-dependent pH increase of maximally 3.4 +/- 0.1, with day-to-day variation over the entire period of 8% +/- 3%. The fistula and pH studies generated similar results. Acid inhibition with esomeprazole increased plasma ghrelin from 10 +/- 2 pmol/L to 65 +/- 26 pmol/L (P < 0.001), and somatostatin from 10 +/- 2 pmol/L to 67 +/- 18 pmol/L (P < 0.001). CONCLUSION: pH measurements with the Bravo capsule are reliable, and comparable to those of the gastric fistula model. The Bravo system optimizes accurate intragastric pH monitoring over prolonged periods and allows both short- and long-term evaluation of effects of drugs and hormones.