Christopher N Andrews

University of Leuven, Louvain, Flanders, Belgium

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Publications (69)484.62 Total impact

  • Himanish Panda · Christopher N Andrews

    No preview · Article · Dec 2015 · Canadian Medical Association Journal
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    ABSTRACT: Bitter taste receptors (TAS2Rs) are present in extra-oral tissues, including gut endocrine cells. This study explored the presence and mechanism of action of TAS2R agonists on gut smooth muscle in vitro and investigated functional effects of intra-gastric administration of TAS2R agonists on gastric motility and satiation. TAS2Rs and taste signalling elements were expressed in smooth muscle tissue along the mouse gut and in human gastric smooth muscle cells (hGSMC). Bitter tastants induced concentration and region-dependent contractility changes in mouse intestinal muscle strips. Contractions induced by denatonium benzoate (DB) in gastric fundus were mediated via increases in intracellular Ca2+ release and extracellular Ca2+-influx, partially masked by a hyperpolarizing K+-efflux. Intra-gastric administration of DB in mice induced a TAS2R-dependent delay in gastric emptying. In hGSMC, bitter compounds evoked Ca2+-rises and increased ERK-phosphorylation. Healthy volunteers showed an impaired fundic relaxation in response to nutrient infusion and a decreased nutrient volume tolerance and increased satiation during an oral nutrient challenge test after intra-gastric DB administration. These findings suggest a potential role for intestinal TAS2Rs as therapeutic targets to alter gastrointestinal motility and hence to interfere with hunger signalling.
    Full-text · Article · Nov 2015 · Scientific Reports

  • No preview · Article · Oct 2015 · BMC proceedings
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    ABSTRACT: The efficacy of gastric neurostimulation therapy for diabetic gastroparesis (GP) in a 'real-life' Canadian setting has not been assessed. To assess changes in health-related quality of life (QoL), weekly vomiting frequency (WVF), total symptom score (TSS) and health care utilization 12 months before and after gastric neurostimulator implantation in a diabetic GP cohort. Medication-refractory diabetic GP patients (n=7, four female, mean age 42 years) were prospectively recruited from 2008 to 2012. QoL scores were self-administered and obtained at baseline, 24 and 48 weeks postimplantion. WVF and TSS were assessed similarly. Health care usage, measured as hospitalization frequency and medication cost, was obtained six and 12 months before and after implant. Changes from baseline to six and 12 months for all outcomes were compared. The mean (± SD) QoL according to EuroQol was significantly better at 24 weeks after the baseline measurement (baseline 29±5, 24 weeks 52±7; P=0.03). The mean improvement in TSS was significantly better at one year postintervention (baseline score 35±5 versus 12 months 27±3; P=0.03). Changes in Short-Form 36 Health Survey and WVF were not significant. Days of GP-related hospitalization were highly variable but decreased from a median of 71 days (range 0 to 227 days) to 29 days (range two to 334 days) one year before and after surgery, respectively (P=0.735). Outpatient medication costs did not decrease to a significant extent. Gastric neurostimulation for diabetic GP appeared to show some beneficial palliative effects overall in the present small open-label series, but the effect is highly variable among patients, and placebo effect cannot be ruled out.
    No preview · Article · May 2015
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    ABSTRACT: Transcutaneous intraluminal impedance measurement (TIIM) is a new method to cutaneously measure gastric contractions by assessing the attenuation dynamics of a small oscillating voltage emitted by a battery-powered ingestible capsule retained in the stomach. In the present study, we investigated whether TIIM can reliably assess gastric motility in acute canine models. Methods. Eight mongrel dogs were randomly divided into 2 groups: half received an active TIIM pill and half received an identically sized sham capsule. After 24-hour fasting and transoral administration of the pill (active or sham), two force transducers (FT) were sutured onto the antral serosa at laparotomy. After closure, three standard cutaneous electrodes were placed on the abdomen, registering the transluminally emitted voltage. Thirty-minute baseline recordings were followed by pharmacological induction of gastric contractions using neostigmine IV and another 30-minute recording. Normalized one-minute baseline and post-neostigmine gastric motility indices (GMIs) were calculated and Pearson correlation coefficients (PCCs) between cutaneous and FT GMIs were obtained. Statistically significant GMI PCCs were seen in both baseline and post-neostigmine states. There were no significant GMI PCCs in the sham capsule test. Further chronic animal studies of this novel long-term gastric motility measurement technique are needed before testing it on humans.
    Full-text · Article · Nov 2014 · Gastroenterology Research and Practice
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    ABSTRACT: Cyclic vomiting syndrome (CVS) is a chronic disorder characterized by episodic nausea and vomiting. A large proportion of patients use marijuana to control their symptoms. Several case reports implicate marijuana as a cause of intractable vomiting with compulsive hot water bathing considered pathognomonic of "cannabinoid hyperemesis." We sought to examine the relationship between marijuana use and CVS. Patients >18 years of age diagnosed by a health care provider were invited to participate in an anonymous internet-based survey. A total of 514 patients participated and 437 completed questions about marijuana use. Mean age was 34 ± 12 years with patients being predominantly female (63 %), Caucasian (92 %) and from the USA (82 %). Nineteen percent never used marijuana and 81 % did. Fifty-four percent used marijuana for health issues and 43 % for recreational purposes. Users stated that it improved nausea, appetite, general well-being, stress levels and vomiting. Users were more likely to be male and have an associated anxiety disorder. Sixty-seven percent of patients reported taking hot showers/baths for symptom relief, and this was associated with marijuana use. (OR 2.54, CI 1.50-4.31, P = 0.0006). Eighty-one percent of patients with CVS who completed an internet survey reported frequent use of marijuana. With marijuana use, patients noted the greatest improvement with stress levels, appetite and nausea. Marijuana users were more likely to be male and have associated anxiety. Hot showers were not pathognomonic of marijuana use though they were more likely to be associated with its use.
    No preview · Article · May 2014 · Experimental Brain Research
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    Full-text · Article · May 2014 · Gastrointestinal Endoscopy

  • No preview · Article · May 2014 · Gastroenterology
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    Full-text · Article · May 2014 · Gastroenterology

  • No preview · Article · May 2014 · Gastroenterology
  • Mohammad Bashashati · Reza A Hejazi · Christopher N Andrews · Martin A Storr
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    ABSTRACT: Gastroesophageal reflux (GER) is a common gastrointestinal process that can generate symptoms of heartburn and chest pain. Proton pump inhibitors (PPIs) are the gold standard for the treatment of GER; however, a substantial group of GER patients fail to respond to PPIs. In the past, it was believed that acid reflux into the esophagus causes all, or at least the majority, of symptoms attributed to GER, with both erosive esophagitis and nonerosive outcomes. However, with modern testing techniques it has been shown that, in addition to acid reflux, the reflux of nonacid gastric and duodenal contents into the esophagus may also induce GER symptoms. It remains unknown how weakly acidic or alkaline refluxate with a pH similar to a normal diet induces GER symptoms. Esophageal hypersensitivity or functional dyspepsia with superimposed heartburn may be other mechanisms of symptom generation, often completely unrelated to GER. Detailed studies investigating the pathophysiology of esophageal hypersensitivity are not conclusive, and definitions of the various disease states may overlap and are often confusing. The authors aim to clarify the pathophysiology, definition, diagnostic techniques and medical treatment of patients with heartburn symptoms who fail PPI therapy.
    No preview · Article · Apr 2014
  • Y. Nasser · M. Bashashati · C. N. Andrews
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    ABSTRACT: Cannabis has been used to treat various afflictions throughout the centuries, including nausea, vomiting, and pain. It has also been used recreationally for its psychotropic properties, which can include a pleasurable ‘high’ feeling and a decrease in anxiety and tension; however, other may experience dysphoria. Changes in cognition and psychomotor performance are also well-known with cannabis use. In recent years, our understanding of the endocannabinoid system (ECS) has progressed dramatically; the objective of identifying agents which may allow modulation of the ECS without significant psychotropic side effects may be possible. Inhibition of fatty acid amide hydrolase (FAAH), an important enzyme for the degradation of anandamide and other endogenous cannabinoids, is a promising target to achieve this goal. In this issue of Neurogastroenterology and Motility, Fichna and colleagues report on a novel selective FAAH inhibitor, PF-3845, with potent antinociceptive and antidiarrheal effects in a mouse model. In this context, we briefly review the components of the ECS, discuss pharmacologic targets for indirect cannabinoid receptor stimulation, and describe recent research with cannabinoids for gut disorders.
    No preview · Article · Apr 2014 · Neurogastroenterology and Motility
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    ABSTRACT: Background Dumping syndrome is characterized by distinct pathophysiological features such as postprandial increase in hematocrit (HT) and pulse rate (PR) and delayed hypoglycemia (HG). Treatment is based on dietary measures and somatostatin analogs (SA), but current SAs have incomplete efficacy, possibly through limited affinity for various somatostatin receptor subtypes. We evaluated the effect of pasireotide, a novel SA with high affinity for 4/5 human somatostatin receptors, on pathophysiological events and symptoms in dumping.Methods Randomized double-blind placebo-controlled cross-over study of nine patients (six women, 47 ± 4 years) with postoperative dumping. Baseline measurements included oral glucose tolerance testing (OGTT), abdominal ultrasound, and dumping symptom severity score (DSSS). Patients were treated for 2 weeks with placebo or pasireotide 300 μg s.c. t.i.d. with a 1-week wash-out in a randomized fashion. On day 13 and 14 of each treatment OGTT, DSSS, and solid and liquid gastric emptying (GE) were obtained.Key ResultsBaseline OGTT was pathological in all patients based on PR (n = 5), HT (n = 1) or HG (n = 7). Compared to placebo, pasireotide suppressed the increase in PR (17.1 ± 2.8 vs 8.2 ± 3.5 bpm; p < 0.05) and late HG (nadir glycemia 55.6 ± 4.3 vs 83.3 ± 9.5 mg/dL; p = 0.007), increased peak glycemia (294.1 ± 33.3 vs 221.0 ± 23.1 mg/dL; p = 0.001) and delayed GE of solids (t1/2 83 ± 23 vs 43 ± 9 min; p = 0.05) and liquids (t1/2 70 ± 10 vs 40 ± 4 min, p = 0.05). The differences in DSSS did not reach statistical significance. Two patients dropped out because of adverse gastrointestinal events under pasireotide.Conclusions & InferencesPasireotide affects pathophysiological features of both early and late dumping syndrome.
    No preview · Article · Apr 2014 · Neurogastroenterology and Motility
  • Yuanyuan Chen · Christopher N. Andrews

    No preview · Article · Jan 2014 · Gastrointestinal Endoscopy
  • Martin Storr · Shane Devlin · Gilaad G Kaplan · Remo Panaccione · Christopher N Andrews
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    ABSTRACT: Cannabinoids are used by patients with inflammatory bowel disease (IBD) to alleviate their symptoms. Little is known on patient motivation, benefit, or risks of this practice. Our aim was to assess the extent and motives for Cannabis use in patients with IBD and the beneficial and adverse effects associated with self-administration of Cannabis. Consecutive patients with IBD (n = 313) seen in the University of Calgary from July 2008 to March 2009 completed a structured anonymous questionnaire covering motives, pattern of use, and subjective beneficial and adverse effects associated with self-administration of Cannabis. Subjects who had used Cannabis specifically for the treatment of IBD or its symptoms were compared with those who had not. Logistic regression analysis was used to identify variables predictive of poor IBD outcomes, specifically surgery or hospitalization for IBD. Cannabis had been used by 17.6% of respondents specifically to relieve symptoms associated with their IBD, the majority by inhalational route (96.4%). Patients with IBD reported that Cannabis improved abdominal pain (83.9%), abdominal cramping (76.8%), joint pain (48.2%), and diarrhea (28.6%), although side effects were frequent. The use of Cannabis for more than 6 months at any time for IBD symptoms was a strong predictor of requiring surgery in patients with Crohn's disease (odds ratio = 5.03, 95% confidence interval = 1.45-17.46) after correcting for demographic factors, tobacco smoking status, time since IBD diagnosis, and biological use. Cannabis was not a predictor for hospitalization for IBD in the previous year. Cannabis use is common in patients with IBD and subjectively improved pain and diarrheal symptoms. However, Cannabis use was associated with higher risk of surgery in patients with Crohn's disease. Patients using Cannabis should be cautioned about potential harm, until clinical trials evaluate efficacy and safety.
    No preview · Article · Jan 2014 · Inflammatory Bowel Diseases
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    ABSTRACT: The stomach plays a critical role in digestion, processing ingested food mechanically and breaking it up into particles, which can be effectively and efficiently processed by the intestines. When the motility of the stomach is compromised, digestion is adversely affected. This can lead to a variety of disorders. Current diagnostic techniques for gastric motility disorders are seriously lacking, and are based more on eliminating other possibilities rather than on specific tests. Presently, gastric motility can be assessed by monitoring gastric emptying, food transit, intragastric pressures, etc. The associated tests are usually stationary and of relatively short duration. The present study proposes a new method of measuring gastric motility, utilizing the attenuation of an oscillator-induced electrical signal across the gastric tissue, which is modulated by gastric contractions. The induced high-frequency oscillator signal is generated within the stomach, and is picked up transluminally by cutaneous electrodes positioned on the abdominal area connected to a custom-designed data acquisition instrument. The proposed method was implemented in two different designs: first a transoral catheter was modified to emit the signal inside the stomach; and second, a gastric retentive pill was designed to emit the signal. Both implementations were applied in vivo on two mongrel dogs (25.50 kg and 25.75 kg). Gastric contractions were registered and quantitatively compared to recordings from force transducers sutured onto the serosa of the stomach. Gastric motility indices were calculated for each minute, with transluminal impedance measurements and the measurements from the force transducers showing statistically significant (p < 0.05) Pearson correlation coefficients (0.65 ± 0.08 for the catheter-based design and 0.77 ± 0.03 for the gastric retentive pill design). These results show that transcutaneous intraluminal impedance measurement has the potential with further research and development to become a useful diagnostic technique.
    Full-text · Article · Jan 2014 · Physiological Measurement
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    Matthew S Linton · Liena Zhao · Xianyong Gui · Martin Storr · Christopher N Andrews
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    ABSTRACT: Esophageal lichen planus (LP) has been described as a cause of nonspecific esophagitis that may cause dysphagia, but its incidence is unknown. We aimed to estimate the incidence of esophageal LP in a defined geographic region and describe the clinical characteristics of affected patients. A histopathology database for a population of 1 million people was searched for all esophageal mucosal biopsy results over an 8-year period. Cases showing inflammation or abnormalities without a diagnosis after three or more biopsies were reviewed for findings of LP. Of 13,589 esophageal biopsies, only one received a diagnosis of LP. Seven patients (four male; mean age, 59 years; range, 39 to 76 years) were identified as having chronic dysphagia and nonspecific proximal esophagitis for which no diagnosis could be made. All patients had proximal inflammation, and six of seven had full-thickness lymphocytic infiltration. Elongation of the lamina propria papillae was noted in all patients, whereas six patients had parakeratosis and ballooning. Only one patient had findings potentially consistent with, but not sufficient for, a diagnosis of esophageal LP. Esophageal LP appears to be extremely uncommon in this North American population, and esophageal biopsy alone is likely not sufficient to establish a diagnosis of LP.
    Preview · Article · Jul 2013 · Gut and liver

  • No preview · Article · May 2013 · Gastroenterology

  • No preview · Article · May 2013 · Gastroenterology

  • No preview · Article · May 2013 · Gastroenterology

Publication Stats

708 Citations
484.62 Total Impact Points

Institutions

  • 2014-2015
    • University of Leuven
      • Translational Research Center for Gastrointestinal Disorders (TARGID)
      Louvain, Flanders, Belgium
  • 2004-2015
    • The University of Calgary
      • • Section of Gastroenterology
      • • Department of Medicine
      • • Faculty of Medicine
      Calgary, Alberta, Canada