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syounger on average (65.5 ±10.7) than bleeding cases (70.0±11.4; p = 0.056). Conclusions:1. The rate of gastrointestinal bleeding among patients on dual antiplatelet therapy afterPCI with PPI co-therapy is 1.8 cases per 100 patient-years. 2. Most bleeding events occurduring the first year of follow-up and are located in the lower GI tract. 3. Risk factorspredictive of a bleeding event are co-therapy with warfarin, age and a peptic ulcer history.

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In Situ Implantation Preserves Myogenic and Neuronal Characteristics ofIntrinsically Innervated Bioengineered Human Internal Anal Sphincter (IAS)Shreya Raghavan, Robert R. Gilmont, Eiichi A. Miyasaka, Richard Herman, Daniel H.Teitelbaum, Khalil N. Bitar

Background: We have successfully implanted bioengineered intrinsically innervated humanIAS tissue constructs in the dorsum of mice. These constructs were neovascularized andphysiologically functional. Objective: We show that bioengineered innervated human IASconstructs implanted in situ above the native IAS of athymic rats, are neovascularized andpreserve physiology of myogenic and neuronal components. Methods: Innervated IAS tissueconstructs comprised of concentrically aligned human IAS smooth muscle and an associatedtri-dimensional fibrous neuronal network. These constructs were implanted for 25 daysabove the native IAS of athymic rats. Results: Rats displayed no altered bowel movementsor signs of colonic obstruction during implantation. Constructs were integrated within therat rectum and appeared pink and vascularized. Colonic wall of the recipient animal wasdissected away. Cross-sections of implanted tissue stained positive for human specific HSP27,indicating phenotypic integrity of implanted tissue. Force-generation analysis displayed: (1)Myogenic basal tone (694±96μN) was generated in tetrodotoxin (TTX; nerve blocker)-insensitive manner, blocked by nifedipine (Ca2+ channel blocker); (2) Relaxation of IAStone by three different modalities: Vasoactive Intestinal Peptide(VIP), nitric oxide(NO) andby electrical field stimulation (EFS). VIP caused a relaxation of basal tone up to 94%,attenuated by TTX to 35%, indicating dual involvement of inhibitory neurons and myogenicsignaling; (3)EFS(10Hz, 0.3ms) caused relaxation of basal tone up to 400μN, abrogated byTTX implying purely neuronal-mediated relaxation. Magnitude of EFS-induced relaxationwas attenuated by pre-treatment with inhibitors of PKA (H89 - 30% inhibition) and NO-synthase (L-NAME - 70% inhibition), providing evidence for presence of VIP-ergic andnitrergic inhibitory innervation; (4) Acetylcholine elicited TTX-sensitive rapid-rising contrac-tions of 800μN, implying involvement of myogenic and neuronal components in cholinergiccontraction; Summary: In situ implantation of intrinsically innervated IAS maintained: 1-Spontaneous generation of myogenic basal tone, a constitutive property of IAS; 2-Integrityof intracellular signaling pathways (VIP & NO) for relaxation of basal tone; 3-Viable TTX-sensitive innervation mediating contraction and relaxation. Conclusion: This is the firstreport of in situ implantation of bioengineered innervated human IAS constructs. In situimplantation in the relevant location did not cause colonic obstruction or disrupt stoolingpatterns. Furthermore, the neuronal as well as myogenic signaling pathways were preservedand mediated multi-pronged IAS relaxation and contraction. This has vast potential toclinically translate autologous functional tissue engineered grafts to repair degenerated IAS.Supported by NIHRO1DK071614 and 1RC1DK087151.

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Efficacy and Safety of Once Daily Linaclotide in Patients With Irritable BowelSyndrome With Constipation: A 12-Week, Randomized, Double-Blind, Placebo-Controlled Phase 3 Trial Followed by a 4-Week Randomized WithdrawalPeriodSatish Rao, Anthony Lembo, Steven J. Shiff, Kelvin Shi, Jeffrey M. Johnston, HarveySchneier

INTRODUCTION: Linaclotide, a minimally absorbed guanylate cyclase-C agonist, is aninvestigational drug for the treatment of IBS-C and chronic constipation. AIMS: To evaluatethe efficacy and safety of linaclotide 266μg (LIN) in patients with IBS-C and the effect ofLIN withdrawal in a Phase 3 clinical trial. METHODS: In this randomized, double-blind,placebo-controlled trial, patients with IBS-C (modified Rome II criteria) with an average of<3 CSBM/week, ≤5 SBM/week, and abdominal pain ≥3 (0-10 scale) during a 2-weekbaseline period received oral, once-daily LIN 266μg or placebo (PBO) over a 12-weektreatment period (TP). In a 4-week randomized withdrawal period (RWP) that followed,LIN patients were re-randomized to continue LIN or receive PBO whereas PBO patientsreceived LIN. Four responder and 10 secondary endpoints were analyzed over 12 weeksusing the Cochran-Mantel-Haenszel test (responder) and Analysis of Covariance (change-from-baseline). RWP measures and safety data were analyzed using descriptive statistics.RESULTS: 800 patients (intention-to-treat population, median age=44, female=90.5%)received LIN (n=405) or PBO (n=395). During the 2-week baseline, 88% had abdominalpain every day (mean score=5.6) and 76% had no CSBMs (mean rate=0.2/week). Comparedto PBO, significantly more LIN patients met all 4 primary endpoints and demonstratedsignificant improvement on all 10 secondary endpoints over 12 weeks (Table). During theRWP, LIN patients who continued LIN showed sustained improvement in abdominal pain,whereas those switched to PBO reported recurrence of pain to the level of PBO patients inthe TP. Conversely, in PBO patients switched to LIN, abdominal pain improved to the levelof LIN patients in the TP within 1 week (Figure). Similar trends were seen with other

S-138AGA Abstracts

endpoints assessed. Diarrhea was the most common adverse event during the TP, causingdiscontinuation in 5.7% (LIN) and 0.3% (PBO) patients. CONCLUSIONS: In patients withIBS-C, LIN treatment produced statistically significant improvements on all 4 primary and10 secondary endpoints of abdominal pain and bowel symptoms compared to PBO. Improve-ments occurred within the first week and were sustained throughout the TP with no evidenceof rebound effect during the RWP.Table of Results

a P-values controlled for multiplicity;b FDA March 2010 Draft Guidance for Industry: IrritableBowel Syndrome-Clinical Evaluation of Products for Treatment;c Mean change from baselineis presented and the Analysis of Covariance is based on rank-transformed data.

846

Differential Effect of Nutrients on Resting State Activity in Lean and ObeseSubjects, Using Functional Connectivity MRI (FcMRI)Lisa A. Kilpatrick, Lynn S. Connolly, Kristen Coveleskie, Jennifer S. Labus, Bahar Ebrat,Jean Stains, Zhiguo Jiang, Brandall Y. Suyenobu, Kirsten Tillisch, Emeran A. Mayer

Ingestive behavior is regulated by the tight interplay between interoceptive and hedonicmechanisms. Uncoupling of this interplay with increased engagement of the hedonic networkhas been suggested in obesity. fcMRI allows identification of functional brain networks andexamination of state-dependent activity without an overt task. To our knowledge, no studyhas identified intrinsic connectivity of a network involved in interoceptive processing oralteration of intrinsic connectivity networks in obese subjects. Aims: 1) To determine ifnutrient ingestion can alter intrinsic connectivity networks in healthy women and 2) if thiseffect differs between lean and obese women. Methods: In a two-day double-blind crossoverdesign, intrinsic connectivity of brain networks was assessed in 10 lean (BMI 19-25kg/m2)and 9 obese (BMI 30-37kg/m2) healthy female subjects following ingestion of a low caloriecarbohydrate drink (LOW; 10 kcal) and a high calorie carbohydrate drink (HIGH; 300kcal). fcMRI data (1.5T) was acquired while subjects rested with eyes closed (10 min).Group independent component analysis was performed to investigate group- and nutrient-related changes in functional connectivity. Results: Multiple networks showed significantgroup or nutrient-related changes in functional connectivity. Decreased connectivity (p<.001)in both groups during HIGH relative to LOW was demonstrated between: (1) right anteriorinsula (aINS) and sensorimotor network (containing homeostatic afferent nodes); (2) midcingulate cortex (MCC) and default mode network (DMN; associated with self-referential