232 Gastric Emptying, Gastric Accommodation, Satiation and Return of Hunger: A Randomized, Single Blind, Cross-Over Study Comparing Soy and Cow Milk in Healthy Volunteers

control) was added instead on the other day. Blood glucose, serum insulin, and plasma glucagon were measured from before until 240 min after ingestion of the test meal. Plasma levels of two incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), were measured until 120 min after the meal. Gastric emptying was assessed over 240 min with a 13C acetate breath test (Breath ID System, Exalenz Bioscience Ltd., Israel). Postprandial dyspeptic symptoms were assessed on a visual analogue scale. Results: The insulin peak occurred significantly earlier with MSG. Postprandial glucose was reduced by MSG, and the decrease was significant at 30 min (58.8 ± 4.4 mg/dl with MSG vs. 68.2 ± 4.3 mg/dl with NaCl, p=0.045 at 30 min postprandially; 53.6 ± 6.1 mg/dl vs. 66.4 ± 6.8 mg/dl, P=0.080 at 45 min). The glucagon level recovered to baseline by 120 min after the meal containing MSG. In contrast, it was still suppressed at 120 min after the meal containing NaCl. However, the area under the concentration versus time curve from 0 to 240 min (AUC (0-240)) for glucose, insulin, or glucagon was not altered by MSG. Plasma GLP-1 was significantly higher at 30 min after the meal containing MSG (58.1 ± 15.8 pmol/L with MSG vs. 13.4 ± 15.8 pmol/L with NaCl, p=0.035). Plasma GLP-1 reached its peak rapidly at 30 min postprandially with MSG, whereas it increased gradually after the meal with NaCl. The half gastric emptying time was not altered by MSG and dyspeptic symptoms were not affected by MSG. Conclusion: MSG induces a more rapid insulin response with improvement of postprandial glycemia and faster recovery of glucagon after intake of a lipid-containing liquid meal. These effects were not associated with a change of gastric emptying, but possibly with increased GLP-1 secretion.

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Background & Aims: Interferon regulatory factors (IRFs) signaling has been known to play a key role in the immune system especially to prevent viral infection. It functions not only as regulators of the interferon (IFN) system, but also as key transcription factors in the regulation of cell growth and apoptosis. IRF1 is known to express ubiquitously, and regulates the expression of several cytokines such as IL-12 and iNOS, however, functionally inactivating point mutation in IRF-1 gene is found in human gastric cancer. Since the function of IRF1 in gastric carcinogenesis remained controversial, we investigated the role of IRF1 in gastric epithelial cells in a mouse model of Helicobacter -dependent gastric inflammation and carcinogenesis. Methods: In order to identify the mechanism in which IRF1 affects the gastric epithelium and carcinogenesis, we used wild-type and IRF1-/- mice. Mice were infected with Helicobacter felis, known as carcinogenic bacteria in stomach. Mice were sacrificed at 3 months post infection. Helicobacter colonization was assessed by histology, and gastric atrophy and metaplasia was scored histologically. Cellular apoptosis and proliferation in the gastric epithelial cells were assessed by measuring caspase-3 activity, and Ki67 immunostaining. Changes in cytokine expression were assessed by qRT-PCR. Results: Mice were healthy and no evidence of growth disturbance was detected over two groups during the observation period. At 3 months post infection, IRF1-/- mice infected with H. felis showed severe gastric inflammation with lymph follicles, neck cell hyperplasia, oxyntic atrophy, and mucous metaplasia especially in gastric corpus, and all of which were severer in IRF1-/mice when compared to wild type mice. Caspase-3 activity index was higher in IRF1-/-, when compared to wild-type mice (WT vs. IRF1-/- = 56.2 vs. 69.1), and the rate of epithelial proliferation was also higher in IRF1-/- mice compared to wild-type mice (Ki67 positive cells per gland; WT vs. IRF1-/- = 8.2 vs. 12.7). mRNA expression of proinflammatory cytokines, IL-6 and TNF, were about 2-fold higher in IRF1-/- stomach, compared to wildtype stomach. Long-term follow-up of infected aged cohorts is ongoing. Conclusion: Loss of IRF signaling leads to increased gastric apoptosis, hyperproliferation, atrophy, and metaplasia, suggesting that IRF signaling in the stomach might cause the alterations in gastric stem and stem cell niche to the development of gastric cancer.

231 Apelin-13 Effects on Peripheral Vagal Afferent Mechanosensitivity With Feeding and Fasting Tracey A. O'Donnell, Stephen J. Kentish, Kristen Healey, Kyle Ratcliff, Gary A. Wittert, Amanda J. Page Background. Apelin is the endogenous ligand for the G-protein coupled receptor, APJ (Tatemoto et al. Biochem Biophys Res Commun 1998;251:471-6). It has been suggested that apelin has a role in the control of food intake. Central administration of apelin13 significantly increases food intake and weight gain in C57/BL6 mice (Valle et al. J. Neuroendocrinol 2008;20:79-84). Apelin is expressed in the gastric mucosa (Susaki et al. Regul Pept 2005;129:37-41) and may therefore have a modulatory effect on gastric vagal afferents but this has not previously been investigated. Aims. To determine: 1) the effect of apelin-13 on the response of tension and mucosal receptors to mechanical stimulation in stomach from ad libitum fed and 14 hour fasted mice; 2) the expression of apelin receptor (APJ) in the nodose ganglia of these mice. Methods. Single fibre recordings of gastroesophageal vagal mechanoreceptors were made in mouse (J Neurophysiol, 2002: 87; 2095). mRNA from nodose ganglia was quantified by real-time RT-PCR. Results: In fed mice, apelin-13 (1-10nM) had no effect on the response of mouse tension receptors to circumferential stretch (1-5g, n=6) or mucosal receptor responses to mucosal stroking with calibrated von Frey hairs (10-1000mg, n=6). However, after a 14hr fast apelin-13 (1-10nM) significantly and dose-dependently reduced the response of both tension receptors (p<0.0001) and mucosal receptors (p<0.05) to mechanical stimulation. The expression of APJ was significantly reduced in nodose ganglia in fasted compared to fed mice (p<0.01). Conclusion: Apelin-13 has a feeding dependent effect on the mechanosensitivity of gastroesophageal vagal afferents consistent with a role of apelin-13 as a regulator of food intake via vagal pathways. This effect cannot simply be explained by an alteration in receptor expression. Further investigation to determine the mechanism of effect is underway. Supported by University of Adelaide and NHMRC (#1023972) Australia

234 Gastrokine-2 Knockout Mice Display Spontaneous Fundic Atrophy and Hypertrophy With Accelerated Progression Following Helicobacter pylori Infection Trevelyan R. Menheniott, Bayzar Kurklu, Heather V. Chalinor, Yok-Teng Chionh, Phil Sutton, Louise M. Judd, Andrew S. Giraud BACKGROUND & AIMS: Gastrokine (GKN) 2 is a member of a family of genes encoding stomach-specific secreted proteins. GKN2 expression is downregulated in Helicobacter pylori (H. pylori) infection and silenced in gastric cancer. GKN2 may therefore participate in the host response to H. pylori and function as a gastric tumour suppressor. While its mode of action remains unclear, the recent demonstration of a secreted GKN2/trefoil factor (TFF)1 heterodimer suggests that GKN2 may regulate the extracellular functions of TFFs. To determine the precise role of GKN2 in gastric physiology and disease we have generated novel Gkn2 knockout mice. METHODS: Gkn2-/- mice were developed by standard gene targeting techniques. Gkn2-/- mice were evaluated for gastric histopathology, inflammation and mucosal composition at 6-, 12- and 30-weeks of age. Transcriptional outcomes of Gkn2 deficiency were investigated by expression microarray and quantitative (Q) RT-PCR analysis. The role of GKN2 in gastritis/preneoplastic progression was determined by infection of Gkn2-/- mice with H. pylori SS1 for 2-months. RESULTS: Gkn2-/- mice showed spontaneous focal atrophy and hypertrophy in the gastric fundus at 6- 12- weeks of age. Mucosal height, cell number per gland and proliferation were increased suggesting deregulation of growth control. Gkn2-/- mice showed reduced parietal and zymogenic cell abundance, with concomitant emergence of spasmolytic polypeptide expressing metaplasia (SPEM) suggesting defective gastric epithelial differentiation. In contrast to the severe pathological outcomes seen in the Gkn2-/- fundus, the antral mucosa remained largely disease-free. Focal fundic atrophy persisted in 30-week old Gkn2-/- mice but did not show additional progression from earlier timepoints. Expression microarray analysis of 12-week Gkn2-/- and wild-type fundus tissues revealed significant differential expression of genes encoding components of gastric acid secretion, cytokine receptor interaction and intracellular calcium signalling. Gkn2-/- mice showed enhanced susceptibility to H. pylori-dependent gastritis characterised by increased inflammation, atrophy and SPEM at 2-months post infection (MPI) compared to infected wild-type controls. CONCLUSIONS: Our data suggest that GKN2 is a key regulator of epithelial differentiation in the gastric fundus and may act as a tumour suppressor by subduing inflammation (acting via associated signalling pathways) and preventing preneoplasia in the context of H. pylori infection.

232 Gastric Emptying, Gastric Accommodation, Satiation and Return of Hunger: A Randomized, Single Blind, Cross-Over Study Comparing Soy and Cow Milk in Healthy Volunteers Pantelis Oustamanolakis, Pieter Janssen, Sofie Verschueren, Kristin Verbeke, Jan F. Tack Background: Anecdotal observations from consumer research indicate that soy products consumption is followed by a feeling of easy digestion, and a light load for the stomach. So far, this aspect has not been scientifically addressed. Aim: To compare the impact of soy and cow milk ingestion on accommodation, satiation and satiety and gastric emptying, in healthy volunteers. Methods: 15 healthy volunteers (HVs; 10 females, 31±2.6 years, 23±0.9 kg/m2) participated in two sessions (one for each type of milk), with one week interval, in this randomized, single-blind study. Milk was labeled with 13C-octanoic acid (200 mg/L) and was infused intragastrically, after a stabilization period, through a transoral infusion catheter, at a constant speed of 60 ml/min, until the volunteer scored max satiation. Intragastric pressure (IGP) was measured through a transnasal, 36-channel, high resolution manometry probe. Breath samples were collected every 15 minutes, for 6 hours, from the beginning of the infusion. Gastric half-emptying time and gastric emptying coefficient (GEC, Ghoos 1993) were calculated from the exhaled 13CO2. Satiation scores were recorded during the infusion and return of hunger and satiety scores for 6 hours after the beginning of the infusion. Results are expressed as mean±SEM and compared with paired Student's t-test. Results: Satiation scores during milk infusion were not different. The volume of milk infused (851±66 and 807±76 ml, P=0.66) and the ingested amount of calories at maximum satiation (383±29.5 and 307±29 kcal, P=0.07) did not differ between cow and soy milk, respectively. Hunger, expected amount to eat and satiety scores were not significantly different, either before, during or after the nutrient infusion. The maximum IGP decrease was 5.5±0.7 mmHg during cow and 4.8±0.6 mmHg during soy milk infusion (P=0.47). Gastric emptying was significantly slower when cow milk was ingested, compared to soy milk: gastric half-emptying time was 97±7 and 61±5 min for cow and soy milk respectively (P=0.0004). GEC was 2.94±0.08 and 3.34±0.08 for cow and soy milk, respectively (P=0.0019). Conclusions: During and after intragastric soy and cow milk infusion, satiation, gastric accommodation, satiety and hunger did not differ. Gastric emptying was, however, markedly increased after soy vs. cow milk ingestion and this may contribute to a perception of “lighter” and “easier digestible” that has been attributed to soy milk. The factors that contribute to faster gastric emptying of soy milk deserve further study.

235 Pseudokinase Tribbles Homolog 3 is Induced in Helicobacter pylori Infected Gastric Mucosa and Contributes to Gastric Carcinogenesis Through Phosphorylation of Oncogenic Protein SHP-2 Yutaka Kondo, Akira Imatani, Naoki Asano, Jun Fushiya, Takashi Chiba, Yasuhiko Abe, Katsunori Iijima, Tomoyuki Koike, Tooru Shimosegawa Background & Aim: Gastric intestinal metaplasia, a pre-cancerous state of gastric cancers, is characterized by reduced expression of Sox2, an HMG box gene involved in the differentiation of oxyntic glands. Helicobacter pylori (H. pylori) infection is known to induce this transdifferentiation, but the details are still unclear. Clarifying the mechanism involved in this formation of intestinal metaplasia may contribute to prevention of gastric cancers. Methods: In the intension of mimicking gastric intestinal metaplasia, we established a murine normal gastric epithelial cell line expressing Sox2-shRNA and aimed to identify the underlying factor

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AGA Abstracts

AGA Abstracts

Loss of IRF Signaling Contributes to the Development of Helicobacter Associated Gastric Carcinogenesis In Vivo Wataru Shibata, Hiroaki Yasuzaki, Yoshiko Kubushiro, Chie Hotta, Tomohiko Tamura, Shin Maeda