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sFurther studies using RT-PCR and western blot analyses confirmed the stimulatory effectsof acidic pH on the endogenous NHE2 mRNA and protein expression, respectively. Inconclusion, our data demonstrate for the first time that induction of Egr-1 expression maybe responsible for the transcriptional activation and expression of NHE2 by acidosis.

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MicroRNA Mir-625 is a Negative Regulator of Human Apical SodiumDependent Bile Acid Transporter (ASBT)Amit Ghosh, Fadi Annaba, Pooja Malhotra, Arivarasu Natarajan Anbazhagan, Pradeep K.Dudeja, Ravinder K. Gill, Waddah A. Alrefai

Apical Sodium-Dependent Bile Acid Transporter (ASBT) is responsible for active absorptionof bile acids mainly in the ileum and is a central modulator of body cholesterol homeostasis.Inhibition of intestinal bile acid absorption reduces high levels of plasma cholesterol associ-ated with diseases such as diabetes mellitus. Recent clinical trials have demonstrated thatblockers of bile acid absorption improve lipid and cholesterol profiles in diabetic patients.Thus, specific inhibitors of ASBT may prove to be more effective therapeutic targets to lowerplasma cholesterol. It is therefore, critical to delineate molecular and cellular mechanismsinvolved in ASBT regulation to develop better therapeuticmodalities for treatment of hyperch-olesterolemia. Recent studies have reported that 3'-untranslated region (3'-UTR) of ASBT iscritical for regulation of ASBT expression. However, the role of micro RNAs (miRNAs) inthe regulation of ASBT expression is not known. Using in silico computational target predic-tion, we initially identified the putative binding site for miR-625 in the 3'UTR of humanASBT mRNA (255bp-251bp downstream of the stop codon) with a context score percentileof 99. Luciferase assays were performed in human intestinal HUTU-80 and Caco2 cells aswell as in kidney HEK293 cells. Mimic of miR-625 was transiently transfected in the cellsalong with a dual luciferase reporter construct (pMIR-GLO vector) containing human ASBT3'-UTR sequence. The 3'-UTR of ASBT constructs demonstrated a significant decrease inrelative luciferase activity as compared to empty vector in HUTU-80 (42.47 ± 1.5%, P<0.01),Caco2 (48.64 ± 2.7%, P<0.01) and HEK293 cells (70.30 ± 4.5%, P<0.01). These datashowed that 3'-UTR is important regulator of ASBT. The validity of miR-625 as a negativeregulator of ASBT expression was evident by co-transfection with mimic of miR-625 thatresulted in a significant decrease in luciferase activity in HUTU-80 (57.54 ± 5.2%, P<0.01),Caco2 (80.89 ± 3.1%, P<0.01) and HEK 293 (70.82 ± 3.6%, P<0.01) cells as compared tocells co-transfected with negative control mimic. To identify the putative binding site ofmiR-625, we generated three ASBT luciferase constructs: 3'-UTR2 (1476bp), UTR3 (753bp)and UTR4 (306bp). Overexpression of miR-625 equally inhibited the luciferase activity ofthe three deletion constructs (UTR2: 71.06 ± 6.6%, P< 0.01; UTR3: 70.04 ± 5.1%, P<0.01;UTR4: 60.67 ± 3.9%, P<0.01), reflecting the in in silico that miR-625 binding site is presentin the smallest 3'-UTR region (UTR4). Taken together, our results show that miR-625 is anovel specific negative regulator of human ASBT. These findings highlight the use of miRNAsas inhibitors of ASBT expression that could be used as potential therapeutic tools for thetreatment of hypercholesterolemia. (Supported by NIDDK & VA)

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Prevalence of Gastro-Esophageal Reflux Disease in Individuals With IrritableBowel Syndrome: A Systematic Review and Meta-AnalysisRebecca M. Lovell, Alexander C. Ford

Background and aims: Irritable bowel syndrome (IBS) and gastro-esophageal reflux disease(GERD) are common disorders in the general population, and there is thought to be a degreeof overlap between the two. However, the strength of this association has not been examinedsystematically.We performed a systematic review andmeta-analysis to estimate the prevalenceof GERD in individuals with IBS. Methods: MEDLINE, EMBASE, and EMBASE Classic weresearched through October 2011 for cross-sectional surveys reporting the prevalence of IBS.A recursive search of the bibliographies of identified articles was also conducted. There wereno language restrictions. Eligible studies were population-based, recruited ≥50 adult (≥15years) subjects, and were required to define IBS via the Manning or Rome criteria, oraccording to a questionnaire. Eligibility assessment and data extraction were conductedindependently in a double-blind fashion by two investigators, with any discrepancies resolvedby consensus. Data were extracted and pooled, with a random effects model, to estimateprevalence of IBS in the population under study. The prevalence of GERD in individualswith and without IBS was compared using an odds ratio (OR), with a 95% confidenceinterval (CI). Results: The search yielded 20 146 results, of which 390 studies appearedrelevant and were retrieved for further assessment. There were 80 separate population-basedstudies that reported the prevalence of IBS according to the various criteria defined above.Of these, 13 studies, containing 49 939 participants, also reported the proportion of peoplewho met criteria for GERD within the same population. The pooled prevalence of IBS inthese 13 studies was 11.6% (95% CI 7.1% to 17.1%). The odds of GERD in individualswith IBS, compared with those without, was 4.17 (95% CI 2.85 to 6.09). Odds of GERDin individuals with IBS varied according to the criteria used to define IBS (see table).Conclusions: The prevalence of GERD in individuals with IBS was four-fold that in thosewithout. The degree of overlap varied according to the criteria used to define IBS, butremained significant in all cases. The strength of this association suggests common pathogen-etic mechanisms.

S-2AGA Abstracts

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Proton Pump Inhibitor Prescription Patterns and Healthcare Utilization inVeterans With a Diagnosis of GERDAndrew Gawron, Scott Miskevics, Elizabeth Tarlov, Bella Etingen, John E. Pandolfino,Sherri L. LaVela

Background: GERD is a prevalent diagnosis in Veterans that may increase health careutilization; this may be mitigated by appropriate PPI prescribing. The study aims were to1) describe PPI prescription patterns in Veterans with GERD; and 2) examine the associationbetween PPI dosing and health care utilization. Methods: We conducted a retrospectivestudy using VA administrative data and reviewed a random sample of medical charts ofGERD patients with an index PPI prescription at Hines VA Hospital from 2003-2007.Exclusion criteria were other diagnoses associated with PPI use, high dose NSAID use, andclopidrogrel use. Index prescriptions were categorized as standard (low dose once daily) orhigh (double dose daily or low dose twice daily) and accuracy was confirmed by manualchart review. Descriptive statistics were calculated for demographics, prescription patterns,and health care utilization (inpatient, outpatient, primary care, and specialty encounters).Bivariate analyses were used to assess differences by PPI dosage category. Results: Patients(n=1621) were classified as having standard (77.5%) and high dose (22.5%) index PPIprescriptions; the chart review showed concordance of >99% for both categories. Patientswere mostly male (97.4%), non-Hispanic white (84.6%), married (60.5%), and 64.6 yearsof age, on average. Demographics did not statistically differ by dosage category. The majorityof patients (65.8%) received a 90-day index prescription; the mean number of refills in the2-year follow up was 6.7. During the 2 year study period, 28.4% of patients were changedto a different PPI type, 17.3% received step up therapy, and 3.8% received step downtherapy. Bivariate analyses (Table 1) showed that the standard dose group had a greatermean number of refills and total days' supply provided. A greater proportion of the standarddose group received step-up therapy than the high dose group (21.3% vs. 3.0%, P<0.0001).A lower proportion of the standard dose group received step down therapy than those inthe high dose group (0.8% vs. 14.5%, P<0.0001). Table 2 shows that patients with standarddose index PPI prescriptions (vs. high dose) had a lower mean number of inpatient stays(0.07 vs. 0.10, P=0.05); a greater proportion of primary care encounters (96.5% vs. 92.0%,P=0.0003), and a lesser proportion of GI endoscopy (12.4% vs. 20.6%, P<0.0001) and ENTclinic (11.2% vs. 23.1%, P<0.0001) encounters. Conclusions: These data highlight variabilityin PPI prescriptions for Veterans with GERD. Efforts to step down PPI therapy may beunderutilized, regardless of index dosing category. Patients with high dose PPI prescriptionsalso had increased health care utilization (ENT and GI endoscopy). These data emphasizethe need to standardize GERD management practices and identify the best treatment optionsbased on Veterans' needs and preferences.Table 1: PPI prescription patterns by index PPI dosage category in Veterans with GERD

1 t test; 2 chi-squared test; 3 263 patients (16%) had no evidence of prescription changeduring 2 years after index prescription; 4 Step up therapy was defined as any change tohigher dose (mg) or frequency (days supply/quantity) or both; step down therapy wasdefined as any change to lower dose (mg) or frequency (days supply/quantity)Table 2: Healthcare utilization by index PPI dosage category in Veterans with GERD