One contentious issue regarding pancreatic acinar exocytosis concerns which SNAP25 isoform (SNAP23/29/47) mediates the various fusion events in this cell type. Based on dominant-negative over-expression studies, SNAP23 was hypothesized to be the putative isoform mediating apical exocytosis, basolateral exocytosis, and ZG-ZG fusion. Unfortunately, using a SNAP23 KD mouse model, 80% SNAP23 KD was insufficient to manifest any secretion phenotype. A novel syncollin-pHluorin exocytosis imaging technique initially meant to assess which fusion events are perturbed by SNAP23 KD was successfully developed and displayed improvements over previous imaging techniques. The syncollin-pHluorin imaging enabled visualization of apical and basolateral exocytosis as well as sequential ZG-ZG fusions. Combined with spinning disk microscopy, this assay allows 3D live exocytosis imaging with high temporal and spatial resolution. This novel imaging assay will be useful in visualizing apical, basolateral, sequential, and lateral fusion events for future acinar studies.

This study presents an integrated analysis of pancreatic ductal adenocarcinomas (PDACs) for identification of putative cancer driver genes in somatic copy number gains (SCNGs). SCNG data on 60 PDAC genomes was extracted to identify 756 genes, mapping to 20 genomic loci that are recurrently gained. Through copy number and gene expression analysis on a panel of 29 human pancreatic cancer cell lines, this gene catalogue was refined to 34 PDAC high-confidence candidate genes. The performance of these genes was assessed in pooled shRNA screens and only ECT2 showed significant essentiality to cell viability in specific PDAC cell lines with genomic gains at the 3q26.3 locus that harbor this gene. Targeted shRNA-mediated interference of ECT2, as well as pharmacological inhibition, are supportive of the pooled shRNA screen findings. These results favor ECT2 as a candidate target gene for further evaluation in the subset of PDACs presenting with 3q26 somatic copy number gains.

One contentious issue regarding pancreatic acinar exocytosis concerns which SNAP25 isoform (SNAP23/29/47) mediates the various fusion events in this cell type. Based on dominant-negative over-expression studies, SNAP23 was hypothesized to be the putative isoform mediating apical exocytosis, basolateral exocytosis, and ZG-ZG fusion. Unfortunately, using a SNAP23 KD mouse model, 80% SNAP23 KD was insufficient to manifest any secretion phenotype. A novel syncollin-pHluorin exocytosis imaging technique initially meant to assess which fusion events are perturbed by SNAP23 KD was successfully developed and displayed improvements over previous imaging techniques. The syncollin-pHluorin imaging enabled visualization of apical and basolateral exocytosis as well as sequential ZG-ZG fusions. Combined with spinning disk microscopy, this assay allows 3D live exocytosis imaging with high temporal and spatial resolution. This novel imaging assay will be useful in visualizing apical, basolateral, sequential, and lateral fusion events for future acinar studies.

This study presents an integrated analysis of pancreatic ductal adenocarcinomas (PDACs) for identification of putative cancer driver genes in somatic copy number gains (SCNGs). SCNG data on 60 PDAC genomes was extracted to identify 756 genes, mapping to 20 genomic loci that are recurrently gained. Through copy number and gene expression analysis on a panel of 29 human pancreatic cancer cell lines, this gene catalogue was refined to 34 PDAC high-confidence candidate genes. The performance of these genes was assessed in pooled shRNA screens and only ECT2 showed significant essentiality to cell viability in specific PDAC cell lines with genomic gains at the 3q26.3 locus that harbor this gene. Targeted shRNA-mediated interference of ECT2, as well as pharmacological inhibition, are supportive of the pooled shRNA screen findings. These results favor ECT2 as a candidate target gene for further evaluation in the subset of PDACs presenting with 3q26 somatic copy number gains.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on July 14, 2009). Includes bibliographical references.

While there has been an opulence of data and studies surrounding the study of the developing pancreas in mammals and other vertebrates, the focus has largely been in mice. The paucity of research in the development of the human pancreas has led to diminished knowledge in the area, compared to other species. Recent discoveries provide growing evidence for discrepancies between mouse and human pancreatic development and diseases and highlight the fact that developmental studies of the pancreas in humans are imperative. The need to develop therapies for diabetes, a growing and one of the leading health problems worldwide, further compels more exploration in this area to deepen our understanding in the different aspects of diabetes in humans and its underlying causes. Research involving modelling human diseases in vitro enables the investigation of the cellular and molecular mechanisms underlying these diseases as well as the development of therapies for treating them. The availability of hPSCs brings with it the advantage of overcoming the limitations of animal models for certain disorders such as pancreatic agenesis, the focus of my project. The use of site-specific nucleases such as TALENs for such a purpose represents a paradigm shift in disease modelling, where TALENs are capable of directly correcting disease-causing mutations, therefore permanently eliminating the symptoms with precise genome modifications. Alternatively, TALENs can also be used to inactivate specific genes by inducing site-specific mutations. Using these tools, I found that GATA6 is required for the formation of the definitive endoderm (DE) and pancreas in humans; hPSCs harbouring homozygous GATA6 mutations fail to form the definitive endoderm, and consequently the pancreas, whereas hPSCs harbouring heterozygous GATA6 mutations exhibited impairment in definitive endoderm development, although it remains unclear if this is a protocol dependent defect. At the pancreatic stage, heterozygous GATA6 mutations consistently compromised pancreas formation regardless of protocol used. I also found that GATA6 transcriptionally activates the development of the definitive endoderm and pancreatic endoderm, and possibly represses the development of mesoderm. Furthermore, I also established that GATA6 directly interacts with key definitive endoderm markers CXCR4 and SOX17, and pancreatic marker PDX1. Taken together, the work herein demonstrates the successful use of hPSCs coupled with the TALEN genome editing technology as a unique in vitro system for disease modelling. These findings also establish two developmental windows, the DE and pancreatic progenitor stages, where GATA6 haploinsufficiency can result in the impairment of pancreatic development leading to pancreatic hypoplasia observed in human GATA6 heterozygous patients. Lastly, my work also provides the molecular mechanism by which GATA6 regulates pancreatic development. Overall, this study provided new insights in the role of GATA6 during development of the human pancreas. These results will be important in developing new methods of differentiation for hPSCs and understanding the interconnection between early organogenesis and late onset of diabetes.

Dietary antioxidant curcumin derived from turmeric has been suggested to decrease the risk of many chronic diseases. Much of the existing data for curcumin stem from experiments performed at supra-physiological concentrations (μM-mM) that are impossible to attain through oral ingestion. It was therefore hypothesized that curcumin at low plasma achievable concentration, though itself not acting as a direct antioxidant might up-regulate the intracellular antioxidants and thus helping combat oxidative stress and protect β-islet cells. The results indicated that Curcumin, DMC and BDMC were able to scavenge hydroxyl radicals, but showed little scavenging ability against superoxide and nitric oxide radicals. Nanomolar concentrations of curcuminoids easily prevented the deleterious effects of H₂O₂ in pancreatic <i>β</i>-islet RINm5F cells. Non of the curcuminoids showed a detrimental effect on insulin secretion, but the model did not allow assessment of any potential positive effect on insulin secretion. The findings confirmed that nanomolar concentrations of curcumin offered protection in pancreatic <i>β</i>-islet cells against H₂O₂-indicated damage by modulating the proportion of oxidised GSH (GSSG): reduced GSH in the favour of GSH and the increasing the activity of SOD. This increase in GSH and SOD levels was, at least in part, on account of an increase in GR, SOD-1 and SOD-2 gene expression. The intracellular mechanism driving this modulation of antioxidant gene was, by virtue of blocking the H₂O₂ induced NF-κB activation.

Made available in DSpace on 2014-06-11T19:23:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-31Bitstream added on 2014-06-13T20:49:47Z : No. of bitstreams: 1 destro_m_me_botib.pdf: 1170172 bytes, checksum: dde49d0cf6d568f068e97098c9cdebe7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O aumento da secreção de insulina estimulada por glicose é um mecanismo adaptativo observado nas ilhotas pancreáticas de animais resistentes à insulina. Estudos relatam que os ácidos graxos livres estimulam a secreção de insulina através da ativação do GPR40. Diante destes fatos, investigamos a secreção de insulina, a expressão de proteínas da via do GPR40 nas células ß e a participação dos lipídios na resistência à insulina induzida por dexametasona, através do tratamento com o redutor de lipídios bezafibrato. Os grupos receberam gavagem uma vez ao dia durante 28 dias: Controle (CTL) e DEXA com goma arábica 5% (1 ml/kg, peso corpóreo); BEZA e BEZA-DEXA com bezafibrato (300 mg/kg, p.c.). Nos últimos 5 dias de tratamento os grupos receberam injeções intraperitoniais: CTL e BEZA de solução salina (1 ml/kg, p.c.); DEXA e BEZA-DEXA de dexametasona (Decadron® 1,0 mg/kg, p.c). A secreção de insulina estimulada por glicose aumentou nos grupos BEZA e DEXA. BEZA-DEXA exibiu diminuição dos níveis de ácidos graxos livres, triglicérides e de insulina, mas não houve elevação dos níveis de glicose no sangue. Além disso, houve melhora na resistência à insulina e restauração do padrão de secreção de insulina, em comparação ao grupo DEXA. Nas ilhotas dos animais BEZA-DEXA a expressão das proteínas GPR40, PLCß1 e PKCδ foi significativamente maior em relação aos valores obtidos em DEXA. Esta via permaneceu inalterada nas ilhotas de DEXA e BEZA. Em conclusão, o tratamento com bezafibrato melhorou a função das células ß e impediu a indução de resistência à insulina pelo tratamento com dexametasona, mas os mecanismos não são conhecidos. O aumento na secreção de insulina em DEXA aparentemente não está relacionado com a ativação do GPR40. Contrariando a literatura, apesar da redução na secreção de insulina, as ilhotas dos animais BEZA-DEXA apresentaram ativação da via do GPR40 / Increased glucose-stimulated insulin secretion is an adaptive mechanism exhibited by pancreatic islets from insulin resistant animal. Studies report that the free fatty acids stimulate the insulin secretion via GPR40. As such, we investigate the expression of GPR40 in ß-cells and the involvement of lipids in dexamethasone-induced IR, by lipid-lowering therapy with bezafibrate. Groups received once daily gavage for 28 days: Control (CTL) and DEXA with gum Arabic 5% (1.0 mg/kg, body weight); BEZA and BEZA-DEXA with bezafibrate (300 mg/kg, b.w.). In the last 5 days of the treatment groups received intraperitoneal injections: CTL and BEZA of saline (1.0 mg/kg, b.w.); DEXA and BEZA-DEXA of dexamethasone (Decadron® 1.0 mg/kg, b.w.). The glucose-stimulated insulin secretion increased in the DEXA and BEZA groups. BEZA-DEXA shows decrease in fatty acids, triglycerides and insulin levels, but not raised blood glucose levels. In addition, there was improved in insulin resistance and restoration the insulin secretory pattern, when compared to DEXA group. In BEZA-DEXA islets, GPR40, PLCß1 and PKCδ protein content was significantly higher than DEXA. This pathway remained unchanged in DEXA and BEZA islets. In conclusion, bezafibrate treatment improved ß-cell function and prevented dexamethasone-induced IR, but the mechanisms are not known. Augmented insulin secretion in DEXA appears to be unrelated to the activation of the GPR40. Contrary to the literature, despite the reduction in insulin secretion, BEZA-DEXA islets showed activation of the GPR40 pathway

Abstract Extraintestinal manifestations in inflammatory bowel disease (IBD) have been described with varying frequencies. The aim of this study was to estimate the prevalence of pancreatic duct abnormalities, exocrine and endocrine dysfunction, elevated pancreatic enzymes, hepato-biliary disease, coexisting cholangiographic and pancreatographic duct changes, and elevated serum levels of fibrosis markers in IBD, and to correlate the findings with clinical, endoscopic and histologic variables. From a local patient register, 237 patients were randomly selected and studied. Of these, 170 had ulcerative colitis (UC), 46 had Crohn's disease (CD), and 21 had indeterminate colitis (IC). A detailed history was obtained from medical records and in a face-to-face interview. The patients were screened with a para-aminobenzoic acid (PABA) test and, for pancreatic enzymes, liver function tests, serum aminoterminal propeptide of type III procollagen (PIIINP), and laminin. Further pancreatic evaluation included endoscopic retrograde cholangiopancreato-graphy (ERCP), ultrasound (US), secretin test, and glucagon C-peptide test. Further hepatobiliary evaluation consisted of ERCP, US, and liver biopsy. In IBD, the prevalence rates of pancreatic duct abnormalities and exocrine dysfunction were 8% and 4%, respectively. Parallel impairment of exocrine and endocrine functions was shown. Acute idiopathic pancreatitis may complicate IBD. About 7-17% presented with elevated pancreatic enzymes. Enzyme elevation was associated with extensive and histologically active disease and, in some cases, with primary sclerosing cholangitis (PSC). Abnormal liver test results were commoner in patients with CD than in patients with UC (30% versus 11%). The prevalence of PSC in IBD was 11%, which is higher than previously reported (3.7-7.5%). PSC was commoner in patients with CD than in patients with UC (17.4% versus 7.6%). About half of the PSC patients had concomitant pancreatic duct changes, and the prevalence of concurrent cholangiographic and pancreatographic duct changes in IBD was 4.6%. Both serum PIIINP and laminin were increased in IBD patients. This was not only seen in patients with hepatobiliary disease and PSC, but also in patients with pancreatic disease. In conclusion, pancreatic and hepatobiliary complications in IBD occur with high and similar frequencies in all IBD categories and are associated with each other. They are not clearly associated with the clinical course of IBD.

Pancreatic pseudocysts are a complication of acute or chronic pancreatitis or result from blunt trauma to the pancreas. It is a localized fluid collection around the pancreas surrounded by a wall of fibrous tissue or inflammation. We present a case of a 56-years old male who presented with abdominal pain and sepsis due to spontaneous rupture of the hemorrhagic pancreatic cyst into the peritoneal cavity and spleen. 56-years old male with medical history of gastroesophageal reflux disease presented with epigastric and left upper quadrant intermittent abdominal pain. Patient denied fever, chills, nausea, and vomiting, family history of pancreatic cancer, anticoagulation use, gallstones, alcohol intake and prior history of pancreatitis. On admission, vitals were B.P 137/82, Pulse 102, RR 16, O2 saturation 92% on room air. Physical exam was significant for left upper quadrant and epigastric tenderness. Labs were lipase 230, amylase 112, lactate 0.7, wbc 7.0, hemoglobin of 15.2 and triglyceride levels were 189mg/dl. Computed tomography (CT) abdomen showed acute pancreatitis and a 4.5 x 4.4 x 2.8 cm cystic lesion between the tail of the pancreas and splenic hilum. Ultrasound of the abdomen showed normal gallbladder with no evidence of biliary ductal dilatation. Magnetic resonance cholangiopancreatography (MRCP) abdomen showed 4.3 cm walled off, possibly hemorrhagic fluid collection, between the spleen and the pancreas. Patient had normal CA-19 level. Patient was evaluated by general surgery who recommended conservative management with repeat CT in 6 weeks with possible pancreatectomy and removal of mass if not resolved. Patient was readmitted 3 days after discharge with worsening abdominal pain and sepsis. Physical exam was significant for epigastric and left upper quadrant tenderness without guarding or rebound. Labs showed lactate 3.4, wbc 11.3, hgb 12.1 and lipase 600. Repeat CT scan showed rupture of the hemorrhagic pancreatic cyst with possible extravasation and enlarged spleen with perisplenic and subcapsular blood represent splenic infarcts. Repeat MRCP confirmed CT findings. Patient was planned for splenectomy and distal pancreatectomy. Most pancreatic pseudocysts resolve spontaneously [1]. Bleeding, infection, rupture, pseudoaneurysm, splenic and biliary complications and portal hypertension are some of the complications if left untreated. Hemorrhage into the pancreatic pseudocyst is a rare complication with a reported incidence of 10-30% with a high mortality rate (40%). Bleeding most commonly involves splenic artery (30–50%), followed by the gastroduodenal artery (17%) and pancreaticoduodenal arteries (11%) [2]. Diagnosis is made by ultrasound, CT scan, MRI or ERCP. Treatment involves either percutaneous drainage, or endoscopic or surgical approach. Spontaneous rupture into the peritoneal cavity is a rare life threatening complication requiring immediate surgical intervention. This case highlights the early recognition of complications of ruptured pancreatic pseudocyst to prevent fatal consequences. References: 1: Lerch MM, Stier A, Wahnschaffe U, Mayerle J: Pancreatic Pseudocysts: Observation, Endoscopic Drainage, or Resection. Deutsches Ärzteblatt International 2009, 106:614-621.10.3238/arztebl.2009.0614. 2: Novacic K1, Vidjak V, Suknaic S, Skopljanac A: Embolization of a large pancreatic pseudoaneurysm converted from pseudocyst (hemorrhagic pseudocyst). JOP 2008, 9:317-21. joplink.net/prev/200805/13.html