R W McCallum

Texas Tech University, Lubbock, Texas, United States

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Publications (423)2541.6 Total impact

  • Reza A Hejazi, Richard W McCallum
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    ABSTRACT: : Rumination is a normal and common phenomenon among ruminant animals; but in humans, it is always regarded as symptom indicative of abnormal function of the upper gastrointestinal tract, and understanding of the mechanisms explaining this event are still evolving. Learning-based theories, organic factors such as gastroesophageal reflux disease and psychological disturbances (eg, depression, anxiety) and the role of life stresses have been postulated as potential mechanisms of rumination. In this review, we take the approach that rumination syndrome is a distinct and discrete functional gastroduodenal disorder. We review current concepts of the pathophysiology of this entity and diagnostic approaches, then detail the treatment paradigms that have been pursued in rumination syndrome in adults. Patients with rumination syndrome have a very distinct set of symptoms. It was focused on the immediate postprandial period, but recently, there is an awareness of an expanding spectrum of the clinical presentation. This includes the concept of "conditioned vomiting" occurring in the setting of delayed gastric emptying (gastroparesis). Physicians' awareness of rumination syndrome is essential in the diagnosis and management of this disorder. Stress and psychological aspects in rumination syndrome are invariably in the background and have to be addressed. The crucial steps in the treatment strategy for rumination syndrome rely on reassurance, education and a physiologic explanation to the patient and family that this is not a "disease," followed by behavioral and relaxation programs and addressing stress factors.
    The American Journal of the Medical Sciences 03/2014; · 1.33 Impact Factor
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    ABSTRACT: IMPORTANCE Gastroparesis remains a challenging syndrome to manage, with few effective treatments and a lack of rigorously controlled trials. Tricyclic antidepressants are often used to treat refractory symptoms of nausea, vomiting, and abdominal pain. Evidence from well-designed studies for this use is lacking. OBJECTIVE To determine whether treatment with nortriptyline results in symptomatic improvement in patients with idiopathic gastroparesis. DESIGN, SETTING, AND PARTICIPANTS The NORIG (Nortriptyline for Idiopathic Gastroparesis) trial, a 15-week multicenter, parallel-group, placebo-controlled, double-masked, randomized clinical trial from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium (GpCRC), comparing nortriptyline with placebo for symptomatic relief in idiopathic gastroparesis. One hundred thirty patients with idiopathic gastroparesis were enrolled between March 2009 and June 2012 at 7 US academic medical centers. Patient follow-up was completed in October 2012. Inclusion criteria included delayed gastric emptying and moderate to severe symptom scores using the Gastroparesis Cardinal Symptom Index (GCSI). INTERVENTIONS Nortriptyline vs placebo. Study drug dose was increased at 3-week intervals (10, 25, 50, 75 mg) up to 75 mg at 12 weeks. MAIN OUTCOMES AND MEASURES The primary outcome measure of symptomatic improvement was a decrease from the patient's baseline GCSI score of at least 50% on 2 consecutive 3-week GCSI assessments during 15 weeks of treatment. RESULTS The primary symptomatic improvement outcome did not differ between 65 patients randomized to nortriptyline vs 65 patients randomized to placebo: 15 (23% [95% CI, 14%-35%]) in the nortriptyline group vs 14 (21% [95% CI, 12%-34%]) in the placebo group (P = .86). Treatment was stopped more often in the nortriptyline group (19 [29% {95% CI, 19%-42%}]) than in the placebo group (6 [9%] {95% CI, 3%-19%}]) (P = .007), but numbers of adverse events were not different (27 [95% CI, 18-39] vs 28 [95% CI, 19-40]) (P = .89). CONCLUSIONS AND RELEVANCE Among patients with idiopathic gastroparesis, the use of nortriptyline compared with placebo for 15 weeks did not result in improvement in overall symptoms. These findings do not support the use of nortriptyline for idiopathic gastroparesis. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00765895.
    JAMA The Journal of the American Medical Association 12/2013; 310(24):2640-9. · 29.98 Impact Factor
  • Mohammad Bashashati, Richard W McCallum
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    ABSTRACT: Nausea and vomiting are common gastrointestinal complaints which could be triggered by stimuli in both the peripheral and central nervous systems. They may be considered as defense mechanisms when threatening toxins/agents enter the gastrointestinal tract or there is excessive retention of gastrointestinal contents due to obstruction. The pathophysiology of nausea and vomiting is complex and much still remains unknown. Therefore, treatments are restricted or ineffective in many cases. Nausea and vomiting with functional etiologies including cyclic vomiting syndrome are challenging in gastroenterology. In this article, we review potential pathways, neurochemical transmitters, and their receptors which are possibly involved in the pathophysiology of nausea and vomiting including the entity cyclic vomiting syndrome.
    European journal of pharmacology 10/2013; · 2.59 Impact Factor
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    ABSTRACT: The following paper on gastroesophageal reflux disease (GERD) and Barrett's esophagus (BE) includes commentaries on defining esophageal landmarks; new techniques for evaluating upper esophageal sphincter (UES) tone; differential diagnosis of GERD, BE, and hiatal hernia (HH); the use of high-resolution manometry for evaluation of reflux; the role of fundic relaxation in reflux; the use of 24-h esophageal pH-impedance testing in differentiating acid from nonacid reflux and its potential inclusion in future Rome criteria; classification of endoscopic findings in GERD; the search for the cell origin that generates BE; and the relationship between BE, Barrett's carcinoma, and obesity.
    Annals of the New York Academy of Sciences 10/2013; 1300(1):278-295. · 4.38 Impact Factor
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    ABSTRACT: This paper presents commentaries on whether Starling's law applies to the esophagus; whether erythromycin affects esophageal motility; the relationship between hypertensive lower esophageal sphincter and vigorous achalasia; whether ethnic- and gender-based norms affect diagnosis and treatment of esophageal motor disorders; health care and epidemiology of chest pain; whether normal pH excludes esophageal pain; the role of high-resolution manometry in noncardiac chest pain; whether pH-impedance should be included in the evaluation of noncardiac chest pain; whether there are there alternative therapeutic options to PPI for treating noncardiac chest pain; and the usefulness of psychological treatment and alternative medicine in noncardiac chest pain.
    Annals of the New York Academy of Sciences 10/2013; 1300(1):96-109. · 4.38 Impact Factor
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    ABSTRACT: Gastric electrical stimulation (GES) is a therapeutic option for intractable symptoms of gastroparesis (GP). Idiopathic GP (ID-GP) represents a subset of GP. A prospective, multicenter, double-blinded, randomized, crossover study to evaluate the safety and efficacy of Enterra GES in the treatment of chronic vomiting in ID-GP. Thirty-two ID-GP subjects (mean age 39; 81% F, mean 7.7 years of GP) were implanted with GES. The stimulator was turned ON for 1½ months followed by double-blind randomization to consecutive 3-month crossover periods with the device either ON or OFF. ON stimulation was followed in unblinded fashion for another 4.5 months. Twenty-five subjects completed the crossover phase and 21 finished 1 year of follow-up. During the unblinded ON period, there was a reduction in weekly vomiting frequency (WVF) from baseline (61.2%, P < 0.001). There was a non-significant reduction in WVF between ON vs OFF periods (the primary outcome) with median reduction of 17% (P > 0.10). Seventy-five percent of patients preferred the ON vs OFF period (P = 0.021). At 1 year, WVF remained decreased (median reduction = 87%, P < 0.001), accompanied by improvements in GP symptoms, gastric emptying and days of hospitalization (P < 0.05). (i) In this prospective study of Enterra GES for ID-GP, there was a reduction in vomiting during the initial ON period; (ii) The double-blind 3-month periods showed a non-significant reduction in vomiting in the ON vs OFF period, the primary outcome variable; (iii) At 12 months with ON stimulation, there was a sustained decrease in vomiting and days of hospitalizations.
    Neurogastroenterology and Motility 07/2013; · 2.94 Impact Factor
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    ABSTRACT: : Nutcracker esophagus is an esophageal motility disorder characterized by the presence of hypertensive contraction waves. These waves can have very high amplitudes, but they maintain a peristaltic pattern and therefore, bolus passage is minimally affected. Esophageal food impactions are rare in nutcracker esophagus. Our patient was a previously asymptomatic man who presented with an esophageal meat impaction due to nutcracker esophagus in which high-resolution manometry played a key role in the diagnosis. Although a rare etiology, nutcracker esophagus can result in esophageal food impaction. High-resolution manometry plays a critical role in the diagnosis of specific motility disorders, even in the setting of minimal symptoms.
    The American Journal of the Medical Sciences 05/2013; · 1.33 Impact Factor
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    ABSTRACT: BACKGROUND: Many patients with gastroparesis have had their gallbladders removed. AIM: To determine if clinical presentations of patients with gastroparesis differ in those with prior cholecystectomy compared to patients who have not had their gallbladder removed. METHODS: Gastroparetic patients were prospectively enrolled in the NIDDK Gastroparesis Registry. Detailed history and physical examinations were performed; patients filled out questionnaires including patient assessment of GI symptoms. RESULTS: Of 391 subjects with diabetic or idiopathic gastroparesis (IG), 142 (36 %) had a prior cholecystectomy at the time of enrollment. Patients with prior cholecystectomy were more often female, older, married, and overweight or obese. Cholecystectomy had been performed in 27/59 (46 %) of T2DM compared to 19/78 (24 %) T1DM and 96/254 IG (38 %) (p = 0.03). Patients with cholecystectomy had more comorbidities, particularly chronic fatigue syndrome, fibromyalgia, depression, and anxiety. Postcholecystectomy gastroparesis patients had increased health care utilization, and had a worse quality of life. Independent characteristics associated with prior cholecystectomy included insidious onset (OR = 2.06; p = 0.01), more comorbidities (OR = 1.26; p < 0.001), less severe gastric retention (OR(severe) = 0.68; overall p = 0.03) and more severe symptoms of retching (OR = 1.19; p = 0.02) and upper abdominal pain (OR = 1.21; p = 0.02), less severe constipation symptoms (OR = 0.84; p = 0.02), and not classified as having irritable bowel syndrome (OR = 0.51; p = 0.02). Etiology was not independently associated with a prior cholecystectomy. CONCLUSIONS: Symptom profiles in patients with and without cholecystectomy differ: postcholecystectomy gastroparesis patients had more severe upper abdominal pain and retching and less severe constipation. These data suggest that prior cholecystectomy is associated with selected manifestations of gastroparesis.
    Digestive Diseases and Sciences 03/2013; · 2.26 Impact Factor
  • Mohammed Saadi, Richard W McCallum
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    ABSTRACT: Irritable bowel syndrome (IBS) is the most common functional bowel disease that affects up to 15% of the US population. The majority of patients with IBS have significant bloating and gas. Recent evidence is beginning to suggest that patients with IBS may have an alteration in the gastrointestinal flora. Specifically, findings suggest that patients with IBS have excessive bacteria in the small bowel, referred to as bacterial overgrowth. Therefore there may be benefits of antibiotic-based therapies for IBS. Rifaximin is a nonabsorbable antibiotic that demonstrates no clinically relevant bacterial resistance. Some studies have demonstrated the efficacy and durable improvement of IBS symptoms after treatment with rifaximin. In this review we explore the current data showing the association of small intestinal bacterial overgrowth (SIBO) and IBS as well as review the available data on the clinical use of rifaximin in the treatment of SIBO in patients with IBS.
    Therapeutic advances in chronic disease. 03/2013; 4(2):71-5.
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    ABSTRACT: OBJECTIVE:: To determine whether bacterial pathogens can be detected within the diseased submucosal tissues of patients with Crohn's disease by molecular techniques independent of cultural methods. DESIGN:: We designed a quantitative polymerase chain reaction to detect 32 virulence genes and transposons within submucosal tissues of patients with Crohn's disease and controls and compared the microbiome of the submucosa with mucosal bacterial populations. RESULTS:: Within submucosal tissues, the bacterial invasion/adherence genes eaeA and invA were detected in 43% of patients (P=0.01 and 0.008 vs. mucosa and controls, respectively) and the Mycobacterium-specific IS900 and 251F genes detected in 50% of patients (P=0.03 vs. mucosa and controls). These findings were mutually exclusive: invasion/adhesion genes and Mycobacterium-associated transposons were not detected in the same patient. Metagenomic sequencing and quantitative polymerase chain reaction results confirmed effective separation of the submucosal and mucosal microbiome and the existence of a submucosal bacterial population within diseased tissues. CONCLUSIONS:: This study is the first to examine the microbial populations of submucosal tissues during intestinal disease and provide evidence of a distinct submucosal microbiome and biotypes within Crohn's disease. These data suggests that Crohn's disease may not be a single disease, but a spectrum that can be divided into distinct biotypes based on the presence of invasion/adherence genes or Mycobacterium-associated transposons. If corroborated by larger population studies, these findings could revolutionize the diagnosis, management, and treatment of Crohn's disease by the identification of patient biotypes and the application of targeted chemotherapeutic treatments that go beyond supportive in nature.
    Journal of clinical gastroenterology 02/2013; · 2.21 Impact Factor
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    ABSTRACT: BACKGROUND: Factors associated with abdominal pain in gastroparesis are incompletely evaluated and comparisons of pain vs other symptoms are limited. This study related pain to clinical factors in gastroparesis and contrasted pain/discomfort- with nausea/vomiting-predominant disease. METHODS: Clinical and scintigraphy data were compared in 393 patients from seven centers of the NIDDK Gastroparesis Clinical Research Consortium with moderate-severe (Patient Assessment of Upper Gastrointestinal Disorders Symptoms [PAGI-SYM] score ≥3) vs none-mild (PAGI-SYM < 3) upper abdominal pain and predominant pain/discomfort vs nausea/vomiting. KEY RESULTS: Upper abdominal pain was moderate-severe in 261 (66%). Pain/discomfort was predominant in 81 (21%); nausea/vomiting was predominant in 172 (44%). Moderate-severe pain was more prevalent with idiopathic gastroparesis and with lack of infectious prodrome (P ≤ 0.05) and correlated with scores for nausea/vomiting, bloating, lower abdominal pain/discomfort, bowel disturbances, and opiate and antiemetic use (P < 0.05), but not gastric emptying or diabetic neuropathy or control. Gastroparesis severity, quality of life, and depression and anxiety were worse with moderate-severe pain (P ≤ 0.008). Factors associated with moderate-severe pain were similar in diabetic and idiopathic gastroparesis. Compared to predominant nausea/vomiting, predominant pain/discomfort was associated with impaired quality of life, greater opiate, and less antiemetic use (P < 0.01), but similar severity and gastric retention. CONCLUSIONS & INFERENCES: Moderate-severe abdominal pain is prevalent in gastroparesis, impairs quality of life, and is associated with idiopathic etiology, lack of infectious prodrome, and opiate use. Pain is predominant in one fifth of gastroparetics. Predominant pain has at least as great an impact on disease severity and quality of life as predominant nausea/vomiting.
    Neurogastroenterology and Motility 02/2013; · 2.94 Impact Factor
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    ABSTRACT: Patient: Female, 82 Final Diagnosis: Achalasia Symptoms: Nocturnal regurgtation • weight loss Medication: - Clinical Procedure: Esophageal stenting Specialty: Gastroenterology • Hepatology Objective: Unusual or unexpected effect of treatment. Pneumatic dilatation is one of the most effective methods for treating achalasia. Esophageal perforation is the most serious complication after pneumatic dilatation and has been reported to occur in the range of 1 to 4.3%. The appropriate management of esophageal perforation can range from conservative medical treatment to surgical intervention. We report a case of an 82-year-old male who had an 8 month history of dysphagia for solid and liquids, a 10 lb weight loss and nocturnal regurgitation. The diagnosis of achalasia was established by endoscopic; barium and manometric criteria. He underwent a pneumatic dilation with a 30 mm Rigiflex balloon. A confined or limited esophageal perforation projecting into the mediastinum and located 1-2 cm above the diaphragm was confirmed by a gastrografin swallow study performed immediately after the procedure. There was some accompanying epigastric abdominal pain. Patient was treated later that day by placing a fully covered metallic esophageal stent in addition to antibiotics, proton pump inhibitor, and fasting. Patient was discharged home 3 days later able to eat liquid-soft foods. Follow up endoscopy 2 weeks later and a gastrografin swallow showed a completely healed perforation and the stent was removed. Symptomatically he has done well, with no dysphagia or heartburn at six and twelve months follow up. Early esophageal stenting for esophageal perforation after pneumatic dilation for achalasia is a treatment option which accelerates healing shortens recovery period, as well as decreasing hospital stay and costs.
    The American journal of case reports. 01/2013; 14:532-535.
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    ABSTRACT: Patient: Female, 25 Final Diagnosis: Rumination syndrome Symptoms: Diarrhea • nausea • vomiting Medication: - Clinical Procedure: - Specialty: Psychology. Rare disease. Rumination syndrome is a behavioral disorder that consists of an effortless regurgitation of undigested food that is subsequently either re-swallowed or ejected within minutes of meal ingestion occurring with liquids and solids. It was first described in children that are mentally disadvantaged but has gained more attention to also occur among both adolescents and adults of normal mental capacity. The prevalence has never accurately been assessed due to its rarity and frequent misdiagnosis. A 25-year-old Caucasian female presented to our care with a chronic history of nausea, vomiting and diarrhea. She has vomited during the postprandial period for the last four years. She also has much as ten bouts of diarrhea per day. There is no definitive evidence of chronic laxative use or self-induced vomiting. Physical examination had no significant findings except a cachectic female patient with a BMI of 16 and hypotension. Patient was eventually discharged home with nutrition recommendations for nocturnal psychology follow up for relaxation behavioral techniques. Due to its elusiveness rumination syndrome is both underdiagnosed and a misdiagnosed condition. One of the reasons for a delayed diagnosis in patients with rumination syndrome is that many physicians are unaware of it, or are even reluctant to make this diagnosis as it could easily be confused with an eating disorder or with other gastrointestinal motility disorders. Because this syndrome may be left undiagnosed for months to years, patients often undergo many expensive and invasive procedures.
    The American journal of case reports. 01/2013; 14:449-52.
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    ABSTRACT: Background  Gastroparesis causes significant morbidity and treatment options are limited. TZP-102 a novel, macrocyclic, selective, oral ghrelin receptor agonist, was evaluated in a randomized, double-blind, placebo-controlled trial in patients with diabetic gastroparesis. Methods  A total of 92 outpatients were randomized to once-daily administrations of 10-mg (n = 22), 20-mg (n = 21), 40-mg (n = 23) TZP-102 or placebo (n = 26). The primary endpoint was the change from baseline in gastric half-emptying time (T(½) ) utilizing (13) C-breath test methodology and secondary endpoints included symptom improvement using patient-reported gastroparesis symptom scores (PAGI-SYM questionnaire) and patient and physician overall treatment evaluations (OTE). Key Results  Gastric T½ changes were not statistically significant between TZP-102 and placebo after 28 days of treatment at any dose. Clinical improvements (-1.0 to -1.4 point mean decrease in symptom severity) occurred in the Gastroparesis Cardinal Symptom Index (GCSI) component of the PAGI-SYM, which was significant vs placebo for all TZP-102 doses combined. Improvements became evident after 1 week of treatment. Significantly, more patients given TZP-102 (any dose) had a 50% reduction in baseline GCSI score (28.8%vs 7.7% placebo). Safety profiles were similar across groups. All TZP-102 doses were well-tolerated with no adverse cardiac, weight, or glucose control outcomes. Conclusions & Inferences  TZP-102 for 28 days, at doses of 10-40 mg once daily, was well-tolerated and resulted in a reduction in symptoms of gastroparesis. The lack of correlation between symptom improvement and gastric emptying change is consistent with previous studies in diabetic gastroparesis, and emphasizes the value of patient-defined outcomes in determining therapeutic benefit.
    Neurogastroenterology and Motility 12/2012; · 2.94 Impact Factor
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    ABSTRACT: Background  Improvement of gastroparesis (GP) symptoms has been documented in patients treated with gastric electrical stimulation (GES), but acceleration of gastric emptying (GET) is unpredictable. The aim of our study was to evaluate the advantage of adding surgical pyloroplasty (PP) to GES for improvement of GET and control of symptoms in diabetes mellitus (DM), idiopathic (ID), and postvagotomy (P-V) GP. Methods  A total of 49 (17 - DM, 9 - ID, 23 - P-V) consecutive GP patients: 38 female; mean age 42 (21-73 years); mean weight 158 lbs (102-245), underwent GES implantation, and 26 (53%) additionally received PP. Total Symptoms Score, 4-h GET, adverse events (AEs), and days of hospitalizations were captured at baseline and at the last visit. Key Results  The mean follow-up was 7 months. Total Symptoms Score in patients who received Enterra and PP or GES alone significantly improved compared to their baseline scores (P < 0.001). GET improved by 64% at 4 h (P < 0.001) in patients with Enterra and PP, compared to 7% observed after GES therapy alone (ns). The most impressive acceleration of GET was seen in the P-V group, who received both therapies (P = 0.004) and 8 (60%) of them normalized GET. No AEs accompanied the addition of PP to the Enterra surgery. Conclusions & Inferences  (i) In drug-refractory GP the addition of PP to GES substantially accelerated GET; (ii) The GET response in P-V group was the most impressive; (iii) Significant symptom reductions were achieved by both procedures; and (iv) PP added to GES may sustain better long-term symptoms control particularly in the P-V setting.
    Neurogastroenterology and Motility 10/2012; · 2.94 Impact Factor
  • Reza A Hejazi, Richard W McCallum, Irene Sarosiek
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    ABSTRACT: Within the last 50 years, diabetic gastroparesis has become a well recognized complication of type 1 and type 2 diabetes. It is a syndrome characterized by abnormal gastric function, resulting in delayed emptying of the stomach in the absence of any evident mechanical obstruction, predominantly manifested by early satiety, postprandial fullness, nausea, vomiting, and weight loss. The past five years have shown significant advances in its pathophysiology and in new diagnostic tests. Prokinetic medications remain the therapeutic focus for improving clinical symptoms of gastroparesis through enhanced gastric emptying. This article summarizes the present knowledge of prokinetics, with emphasis on medications currently available, as well as drugs under clinical investigation, including some agents in advanced clinical trials that are likely to be used in the treatment of diabetic gastroparesis in the future. These include the ghrelin agonists and newer 5-HT4 agonists devoid of cardiac side effects.
    Current Gastroenterology Reports 06/2012; 14(4):297-305.
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    ABSTRACT: The molecular mechanisms of cellular changes responsible for diabetic gastroparesis, primarily seen in middle-aged women, still remain incompletely defined. We hypothesized that a decrease in the expression, dimerization, and post-translational modification of neuronal nitric oxide synthase alpha (nNOSα) is estrogen mediated and responsible for the gender-specific prevalence of this malady. We induced diabetes by injecting male and female rats with streptozotocin. Male diabetic rats without gastroparesis were then injected with estrogen for 3 weeks and evaluated for gastroparesis development. Gastric tissues were analyzed for the elucidation of biochemical events associated with diabetes and gastroparetic dysfunction. Although male diabetic, gastroparetic (either streptozotocin- or estrogen-induced) rats exhibited similarity in disease pathology to that of females, the molecular mechanisms of development were different. Our results indicate that slow gastric emptying in both male diabetic, gastroparetic rat groups was not associated with the level of expression of nNOSα in gastric tissues. However, nNOSα dimerization, which reflects nNOSα activation, did decline slightly in the antrum of diabetic males with estrogen-induced gastroparesis, suggesting a possible estrogen role. Females with diabetic gastroparesis, in contrast, demonstrated significantly impaired levels and dimerization of nNOSα in the antrum and pylorus. Although the precise mechanism remains unknown, nNOSα dimerization impairment in female antrum is apparently associated with reduced phosphorylation of Ser(1416) in the activation loop of nNOSα. Taken together, these results demonstrate that gender and estrogens may be leading factors, through molecular changes involved in nitric oxide synthesis down-regulation, within the antrum and pylorus of female diabetic, gastroparetic rats.
    Digestive Diseases and Sciences 06/2012; 57(11):2814-25. · 2.26 Impact Factor
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    ABSTRACT: Enterra gastric electrical stimulation (GES) is an alternative treatment for gastroparesis (GP) when standard medical therapy fails. The aims of this study were to evaluate the association between total symptom score (TSS) and reduction in gastric retention (GR) after GES by GP etiology and to examine the sensitivity of the association to varying cutpoints used to define GR and TSS improvement. Gastric retention assessed with a standardized (99m) Tc radio-labeled egg meal and TSS measured by a five-point Likert scale in 221 GP patients treated with Enterra GES therapy for at least 1 year were analyzed. Bivariate chi-square test and multivariable logistic regression with all possible cutpoints were used to assess the consistency of association and quantitate the relationship across three GP etiologies. Symptom relief in diabetic GP was more likely attributable to GR reduction as indicated by the consistently significant odds ratios (P < 0.01) across all cutpoints. The association in idiopathic GP was inconclusive because odds ratios were sensitive to cutpoints with P-values ranging from 0.01 to 0.47. No association was found for patients with post surgical gastroparesis (P > 0.1 for all cutpoints). Patient age, gender, baseline TSS and baseline GR had no significant effect at 5% level on clinical improvement regardless of cutpoints for GR. Association between clinical improvements and GR reduction following GES treatment depends on patient etiology and was able to be demonstrated in diabetic GP. The association for idiopathic GP was inconclusive and no such association was found for post surgical GP across all possible cutpoint combinations.
    Neurogastroenterology and Motility 04/2012; 24(7):639-45, e274. · 2.94 Impact Factor
  • Article: Reply.
    Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 03/2012; · 5.64 Impact Factor
  • Jieyun Yin, Thomas D Abell, Richard W McCallum, Jiande D Z Chen
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    ABSTRACT: Gastric electrical stimulation (GES) has been introduced for treating gastric motility disorders, such as gastroparesis, and obesity. A special method of GES using high frequency-short pulses, called Enterra® Therapy, has been clinically applied to treat nausea and vomiting in patients with gastroparesis. However, its mechanisms are not well understood. General methodologies of GES published in the literature are systematically reviewed and their main effects and application are presented. The major part of this review is focused on Enterra Therapy since this is the only method that has been used clinically. A number of different GES methods have been proposed. GES with long pulses or dual pulses, but not short pulses, are able to alter (enhance or inhibit) such parameters of gastric motility as gastric slow waves and gastric emptying. Synchronized GES has been reported to improve antral contractions. GES with high frequency-short pulses, or Enterra Therapy, is known to improve nausea and vomiting in patients with gastroparesis and has a response rate of 50-70%. Improved gastric accommodation, direct enteric nervous system effects, enhanced vagal activity, and activation of central neurons are believed to be the underlying mechanisms involved in the antiemetic effect of this therapy. GES with high frequency-short pulses effectively reduces nausea and vomiting in patients with gastroparesis. This antiemetic effect could be mediated via enteric, autonomic, and/or central neural mechanisms. Further systematic and controlled studies are needed to improve the efficacy of Enterra Therapy and to understand its mechanisms of action.
    Neuromodulation 02/2012; 15(3):224-31; discussion 231. · 1.19 Impact Factor

Publication Stats

7k Citations
2,541.60 Total Impact Points


  • 2013
    • Texas Tech University
      Lubbock, Texas, United States
    • The University of Calgary
      • Department of Physiology and Pharmacology
      Calgary, Alberta, Canada
  • 2010–2013
    • Temple University
      • • Section of Gastroenterology
      • • Department of Medicine
      Philadelphia, PA, United States
    • Aarhus University
      Aarhus, Central Jutland, Denmark
  • 2009–2013
    • Texas Tech University Health Sciences Center
      • • Department of Medicine
      • • Department of Internal Medicine
      Lubbock, TX, United States
    • Children's Hospital Los Angeles
      • Division of Medical Genetics
      Los Angeles, California, United States
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States
    • Louisiana State University Health Sciences Center New Orleans
      • Department of Pediatrics
      New Orleans, LA, United States
    • University of Iowa
      Iowa City, Iowa, United States
  • 2012
    • William Beaumont Army Medical Center
      El Paso, Texas, United States
    • Northwestern University
      Evanston, Illinois, United States
  • 2009–2012
    • University of Texas at El Paso
      El Paso, Texas, United States
  • 1997–2012
    • Kansas City VA Medical Center
      Kansas City, Missouri, United States
  • 2011
    • University of Louisville
      • Division of Gastroenterology, Hepatology and Nutrition
      Louisville, KY, United States
  • 1997–2011
    • Kansas City University of Medicine and Biosciences
      • • Department of Neurology
      • • Department of Surgery
      Kansas City, Missouri, United States
  • 2008–2009
    • University of Michigan
      • • Department of Internal Medicine
      • • Division of Gastroenterology
      Ann Arbor, MI, United States
    • Hackensack University Medical Center
      Hackensack, New Jersey, United States
  • 2006–2009
    • Children's Mercy Hospitals and Clinics
      Kansas City, Missouri, United States
  • 2006–2008
    • Children's Mercy Hospitals and Clinics
      Kansas City, Missouri, United States
  • 2002–2006
    • University of Kansas
      • Department of Surgery
      Lawrence, Kansas, United States
  • 2005
    • Dalian University of Technology
      • School of Electronic and Information Engineering
      Dalian, Liaoning, China
    • Children's Mercy Hospital
      Kansas City, Missouri, United States
  • 2000
    • Texas A&M University - Galveston
      Galveston, Texas, United States
    • Florida Atlantic University
      • Center for Complex Systems and Brain Sciences
      Boca Raton, FL, United States
  • 1983–1999
    • Yale-New Haven Hospital
      New Haven, Connecticut, United States
  • 1986–1997
    • University of Virginia
      • • Department of Medicine
      • • Division of Maternal Fetal Medicine
      Charlottesville, VA, United States
  • 1995
    • St. Mary Medical Center
      Long Beach, California, United States
  • 1980–1989
    • Yale University
      • Department of Internal Medicine
      New Haven, CT, United States