POSTER PRESENTATIONS

340 | CANADIAN JOURNAL OF DIABETES

The Reporting of Cardiovascular Risk Associated with Rosiglitazone in the Lay Press. DOREEN M RABI*, GARIELLE BROWN, ADRIANE M. LEWIN, ALUN L. EDWARDS, JEFFREYA JOHNSON and WILLIAM A. GHALI, Dept. of Medicine, University of Calgary, Dept. of Public Health Sciences, University of Alberta.

Recent studies suggesting an association between rosiglitazone use and increased risk for adverse cardiovascular (CV) events were reported extensively in the lay media. As definitive trials evaluating the CV safety of this therapy are ongoing- rosiglitazone remains available for use. The objective of this study was to determine how the putative CV risk of rosiglitazone was communicated to the public in lay media articles. Using the Factiva media database, lay press articles containing the keywords “rosiglitazone” or “Avandia”, published between May 18 and August 31, 2007 were identified. Articles that did not address the safety of rosiglitazone were excluded. Two reviewers (one lay, one medical) screened full text articles for eligibility, and appraised them for tone (worrisome, neutral, not worrisome), and for reporting of risk (relative, absolute, not specified). Data was extracted in duplicate to determine agreement between reviewers. Our search identified 156 articles of which 95 were eligible for inclusion. Agreement between reviewers in the appraisal of the title or article tone was 67.4%. Among the articles with agreement, both titles (58.4%) and articles(75.3% ) were most often appraised as “worrisome.” Among those with disagreement, the lay reviewer was significantly more likely than the medical reviewer to appraise the titles (58.1% vs. 35.5%, X2 = 5.13, p=0.02) and articles (77.4% vs. 3.2%, X2 = 9.11, P=0.003) as worrisome. Cardiovascular risk was discussed in 91.6% of the articles. Of the 58.6% of articles that expressed risk numerically, 98% reported relative risk but only 4.2% stated whether the risk reported was relative or absolute in nature. In 41.4%, risk was discussed only qualitatively. The reporting of relative risk was not associated with overall appraisal of the article (X2 = 0.55, p=0.97). Lay media articles addressing rosiglitazone safety were generally appraised as “worrisome”, and were more likely to be seen as worrisome by the lay reviewer. The impact of such media coverage on public anxiety and confidence in treatment should be explored.

ABSTRACT #189

C&SS

OTHER: KNOWLEDGE TRANSLATIONEffects of the Co-encapsulation of Pancreatic Islets and Duct cells on Cell Survival: choice of the Culture Medium. GENEVIEVE LANGLOIS*, JULIE DUSSEAULT, JEAN-PIERRE HALLÉ, Maisonneuve-Rosemont Hospital Research Centre, Montréal, QC.

The limited duration of islet survival is an important issue for free and microencapsulated islet transplantation. It has been shown thatin vitro incubation with duct cells decreases islet apoptosis and necrosis. We previously showed that a 48 hours pre-transplantation incubation in IGF-II, the principal peptide secreted by duct cells, improves in vitro and in vivo islet survival micro-encapsulated. Wehypothesise that co-encapsulating duct cells with islets will have a prolonged positive effect on islet survival both in vitro and in vivo after transplantation The standard culture medium for duct cells is IMENZO whereas we use to culture islets in CMRL. The objective of the present study is to select the proper culture medium for incubating co-encapsulated islets and duct cells for the in vitro studies. We evaluated the effects of these two cultures media on duct cells and islet cells viability using standard procedures (Trypan blue exclusion for ductal cells and two nucleic acid dyes (AO/PI) for islets. Also, we evaluated the number of cells presenting a necrosis center and their diameter with inverted light microscopy. Duct cells were more viable (94%, 94%, 90%) in the IMEMZO compared to CMRL (56%, 38%, 46%) at days 6, 17 and 31 respectively. Furthermore, we observed that duct cells were more proliferative in IMEMZO (2.17X106 cells) then cultured in CMRL with 22.75 X103 cells for the day 31. The number of viable islets, 72% and 48%, was similar when they were cultured in IMEMZO and with CMRL, 44% and 25%, at day 7, 14 respectively. These differences were not statistically significant. Finally, duct cells present poor viability when cultured in CMRL for more than 6 days, whereas both duct cells and islets present good viability in IMEMZO. Therefore, IMEMZO will be used for our experiments on co-encapsulated islets and duct cells with the in vitro studies and they will be conducted within 6 days after their last passage.

ABSTRACT #89

C&SS

TRANSPLANTATION

The Fate of Extracellular Matrix and Intra-Islet Endothelial Cells in Encapsulated Islets. JULIE DUSSEAULT*, JEAN-PIERRE HALLÉ, Maisonneuve-Rosemont Hospital Research Centre, Maisonneuve-Rosemont Hospital, Montréal, QC

Islet survival is an important issue in free and microencapsulated islet transplantation. It has been shown that extracellular matrix molecules (ECM) play a role in the regulation of islet cell survival, differentiation, migration, replication and apoptosis. A key recent finding is that beta-cells do not produce ECM. Instead, these ECM are produced by endothelial cells (ECs). In fact, beta-cells release a factor, VEGF-A, which attract ECs within islets. The objective of our research is to evaluate the role of ECs and ECM molecules (laminin, fibronectin, collagen I and IV) that are produced by ECs and are ligands of beta-cell integrins ß1, on microencapsulated islet survival, and to use this knowledge to develop methods to promote islet cell survival. The first step of this study was to determine, in vitro fate of ECM and ECs in encapsulated islets at 0, 7 and 14 days, using immunohisto-chemistry and immunofluorescence. We found that non-encapsulated islets as well as encapsulated islet showed positive staining for type I and type IV collagens and integrin

1, 7 and 14 days post-isolation. Moreover, the distribution of the integrin 1 was varying in time when islets were encapsulated. Further studies are required to develop methods to promote islet survival, such as that a co-encapsulation of islets with ECM producing endothelial cells.

ABSTRACT #88

C&SS

TRANSPLANTATION

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Calcium-dependent effects of palmitate on -cell apoptosis and function JAMES D. JOHNSON*, KAMILA GWIAZDA, KRISTIN JEFFREY, DAN S. LUCIANI

There are strong links between obesity, elevated free fatty acids, and type 2 diabetes. In the present study, we sought to determine the mechanisms by which palmitate affects intracellular Ca2+, and in particular the endoplasmic reticulum (ER). In human -cells and MIN6 cells, palmitate increased cytosolic Ca2+ through a combination of Ca2+

store release and extracellular Ca2+ influx. Palmitate caused reversible ER Ca2+ depletion, directly measured with the fluorescent protein-based ER Ca2+ sensor D1ER. Using another genetically encoded indicator, we observed sustained oscillations of cytosolic Ca2+ in palmitate-treated cells. In keeping with the observed ER Ca2+ depletion, palmitate induced ER-stress and -cell death. Palmitate metabolism and Ca2+ influx were required for rapid, degradation of carboxypeptidase E, which in turn caused a defect in insulin processing, ER-stress and apoptosis. We detected little palmitate-induced insulin secretion, suggesting these Ca2+ signals are poorly coupled to exocytosis. In summary, we have characterized Ca2+-dependent mechanisms involved in altered -cell function and survival induced by the free fatty acid palmitate. We present the first direct evidence that palmitate reduces ER Ca2+ and shed light on pathways involved in lipotoxicity and the pathogenesis of type 2 diabetes.

ABSTRACT #97

C&SS

ISLET BIOLOGY