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Exocrine Pancreas (exocrine + pancreas)
Selected AbstractsVMAT2 quantitation by PET as a biomarker for ,-cell mass in health and diseaseDIABETES OBESITY & METABOLISM, Issue 2008M. Freeby The common pathology underlying both type 1 and type 2 diabetes (T1DM and T2DM) is insufficient ,-cell mass (BCM) to meet metabolic demands. An important impediment to the more rapid evaluation of interventions for both T1DM and T2DM lack of biomarkers of pancreatic BCM. A reliable means of monitoring the mass and/or function of ,-cells would enable evaluation of the progression of diabetes as well as the monitoring of pharmacologic and other interventions. Recently, we identified a biomarker of BCM that is quantifiable by positron emission tomography (PET). PET is an imaging technique which allows for non-invasive measurements of radioligand uptake and clearance, is sensitive in the pico- to nanomolar range and of which the results can be deconvoluted into measurements of receptor concentration. For BCM estimates, we have identified VMAT2 (vesicular monoamine transporter type 2) as a biomarker and [11C] DTBZ (dihydrotetrabenazine) as the transporter's ligand. VMAT2 is highly expressed in ,-cells of the human pancreas relative to other cells of the endocrine and exocrine pancreas. Thus measurements of [11C] DTBZ in the pancreas provide an indirect measurement of BCM. Here we summarize our ongoing efforts to validate the clinical utility of this non-invasive approach to real-time BCM measurements [source] C-peptide constricts pancreatic islet arterioles in diabetic, but not normoglycaemic miceDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2008Lina Nordquist Abstract Background Pancreatic islet blood flow is regulated separately from that of the exocrine pancreas, and a consistent finding during impaired glucose tolerance is an increased blood perfusion. The aim of the present study was to investigate whether C-peptide affects pancreatic islet arterioles in normal and diabetic mice. Materials and Methods Control and diabetic C57-Bl mice were studied after 2 weeks of alloxan-induced diabetes. Islet arterioles were dissected and microperfused with Dulbecco's modified Eagle medium (DMEM) solution. The effect of luminal application of mouse C-peptide was investigated. Results C-peptide reduced the diameter of islet arterioles from diabetic mice (,10 ± 4%, P < 0.05) compared to base-line values, whilst arterioles from normoglycaemic animals did not respond to C-peptide (P = 0.2). Conclusion These findings suggest a role for C-peptide in the regulation of islet blood flow, especially during conditions with impaired glucose tolerance. Copyright © 2007 John Wiley & Sons, Ltd. [source] Decreased expression and promoter methylation of the menin tumor suppressor in pancreatic ductal adenocarcinomaGENES, CHROMOSOMES AND CANCER, Issue 5 2009Ilaria Cavallari Loss of menin, a tumor suppressor coded by the MEN1 gene, is a key factor in the pathogenesis of multiple endocrine neoplasia type I and in a percentage of sporadic endocrine tumors of the pancreas and parathyroid glands. This study investigated expression of the menin protein in the normal exocrine pancreas and in pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic tumor. Immunofluorescence (IF) analyses showed that menin is expressed at high levels in normal acinar and duct cells. Examination of 24 clinical samples of PDAC revealed a pronounced decrease in menin expression in all tumors examined. To identify alterations underlying this defect, we searched for disruption and epigenetic silencing of the MEN1 gene. Analysis of nine laser-microdissected tumors revealed loss of heterozygosity of intragenic (one tumor) or adjacent (three tumors) MEN1 microsatellite markers. Methylation of CpG sites in the MEN1 promoter was documented in five of 24 tumors. IF analyses also revealed low to undetectable menin expression in the PDAC cell lines MiaPaCa-2 and Panc-1. Ectopic expression of menin in these cells resulted in a marked alteration of the cell cycle, with an increase in the G1/S+G2 ratio. These findings represent the first evidence that the MEN1 gene is a target of mutation and methylation in PDAC and that menin influences the cell cycle profile of duct cells. © 2009 Wiley-Liss,Inc. [source] Experimental transmission of sleeping disease in one-year-old rainbow trout, Oncorhynchus mykiss (Walbaum), induced by sleeping disease virusJOURNAL OF FISH DISEASES, Issue 5 2006S Kerbart Boscher Abstract Sleeping disease (SD) is a serious disease of rainbow trout, Oncorhynchus mykiss, reared in fresh water caused by sleeping disease virus (SDV). In this study a detailed clinical, histological, virological and serological description of the experimental reproduction of SD in 1-year-old rainbow trout exposed to SDV was carried out. Two hundred disease-free fish were intraperitoneally inoculated with a SDV isolate and 100 fish were inoculated with an uninfected cell culture lysate as a negative control. Infected and control fish were randomly removed at days 4, 7, 14, 21, 42 and 70 post-infection. Blood and tissues were collected for virus isolation, histopathological examination and serum neutralization. SDV was detected in serum, kidney and brain of infected fish from 4 to 21 days post-infection (dpi). Characteristic pathological lesions were observed in infected fish as early as 7 dpi. Lesions were first detected in exocrine pancreas and subsequently observed in heart and skeletal muscle. Neutralizing antibodies to SDV were detected in infected fish from 14 to 70 dpi. Infected fish displayed typical signs of SD 1-month pi and the mortality reached 18.7% within 44 days. This study experimentally reproduced all the pathognomonic features of natural outbreaks of SD in 1-year-old rainbow trout. [source] Involvement of vH+ -ATPase in synaptic vesicle swellingJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2010Leah Shin Abstract Secretory vesicle swelling is central to cell secretion, but the underlying mechanism of vesicle swelling, particularly synaptic vesicles, is not completely understood. The G,i3 -PLA2-mediated involvement of water channel AQP-1 in the regulation of secretory vesicle swelling in exocrine pancreas and the G,o -mediated AQP-6 involvement in synaptic vesicle swelling in neurons have previously been reported. Furthermore, the role of vH+ -ATPase in neurotransmitter transport into synaptic vesicles has also been shown. Using nanometer-scale precision measurements of isolated synaptic vesicles, the present study reports for the first time the involvement of vH+ -ATPase in GTP-G,o -mediated synaptic vesicle swelling. Results from this study demonstrate that the GTP-G,o -mediated vesicle swelling is vH+ -ATPase dependent and pH sensitive. Zeta potential measurements of isolated synaptic vesicles further demonstrate a bafilomycin-sensitive vesicle acidification, following the GTP-G,o -induced swelling stimulus. Water channels are bidirectional and the vH+ -ATPase inhibitor bafilomycin decreases both the volume of isolated synaptic vesicles and GTP-mastoparan stimulated swelling, suggesting that vH+ -ATPase is upstream of AQP-6, in the pathway leading from G,o -stimulated swelling of synaptic vesicles. Vesicle acidification is therefore a prerequisite for AQP-6-mediated gating of water into synaptic vesicles. © 2009 Wiley-Liss, Inc. [source] Melatonin and its precursor, L -tryptophan: influence on pancreatic amylase secretion in vivo and in vitroJOURNAL OF PINEAL RESEARCH, Issue 3 2004Jolanta Jaworek Abstract:, Melatonin, considered as a main pineal product, may be also synthetized in the gastrointestinal tract from l -tryptophan. Melatonin has been recently shown to affect insulin release and its receptors have been characterized in the pancreas however, the effects of melatonin on the pancreatic enzyme secretion have not been examined. The aim of this study was to investigate the effects of melatonin or l -tryptophan on amylase secretion in vivo in anaesthetized rats with pancreato-biliary fistulas, and in vitro using isolated pancreatic acini. Melatonin (1, 5 or 25 mg/kg) or l -tryptophan (10, 50 or 250 mg/kg) given to the rats as a intraperitoneal (i.p.) bolus injection produced significant and dose-dependent increases in pancreatic amylase secretion under basal conditions or following stimulation of enzyme secretion by diversion of bile-pancreatic juice. This was accompanied by a dose-dependent rise in melatonin plasma level. Stimulation of pancreatic enzyme secretion caused by melatonin or l -tryptophan was completely abolished by vagotomy, deactivation of sensory nerves with capsaicin or pretreatment with CCK1 receptor antagonists (tarazepide or l -364,718). Pretreatment with luzindole, an antagonist of melatonin MT2 receptor failed to affect melatonin- or l -tryptophan-induced amylase secretion. Administration of melatonin (1, 5 or 25 mg/kg i.p.) or l -tryptophan (10, 50 or 250 mg/kg i.p.) to the rats resulted in the dose-dependent increase of cholecystokinin (CCK) plasma immunoreactivity. Enzyme secretion from isolated pancreatic acini was not significantly affected by melatonin or l -tryptophan used at doses of10,8,10,5 m. We conclude that exogenous melatonin, as well as that produced endogenously from l -tryptophan, stimulates pancreatic enzyme secretion in vivo while increasing CCK release. Stimulatory effect of melatonin or l -tryptophan on the exocrine pancreas involves vagal sensory nerves and the CCK release by these substances. [source] Beer But Not Wine, Hard Liquors, or Pure Ethanol Stimulates Amylase Secretion of Rat Pancreatic Acinar Cells In VitroALCOHOLISM, Issue 9 2009Andreas Gerloff Background:, In contrast to pure ethanol, the effect of alcoholic beverages on the exocrine pancreas is greatly unknown. Besides ethanol, alcoholic beverages contain numerous nonalcoholic constituents which might have pathophysiological effects on the pancreas. The aim of the present study was to investigate whether some commonly used alcoholic beverages and pure ethanol influence the main function of rat pancreatic acinar cells, i.e., enzyme output in vitro. Methods:, Rat pancreatic AR4-2J cells were differentiated by dexamethasone treatment for 72 hours and freshly isolated pancreatic acini were prepared from Sprague,Dawley rats using collagenase digestion. After incubation of cells in the absence or presence of 1 to 10% (v/v) beer (containing 4.7% v/v ethanol), 10% (v/v) wine (containing 10.5 to 12.5% v/v ethanol), 10% (v/v) hard liquor (such as whisky, rum, and gin), or of the corresponding ethanol concentrations (4.03 to 80.6 mM) for 60 minutes, protein secretion was measured using amylase activity assay. Results:, Incubation of AR4-2J cells with beer caused a dose-dependent stimulation of basal amylase secretion that was significant at doses of beer above 0.5% (v/v). Stimulation with 10% (v/v) beer induced 92.7 ± 25.2% of maximal amylase release in response to the most effective cholecystokinin (CCK) concentration (100 nM). In contrast, ethanol (up to 80.6 mM) did neither stimulate nor inhibit basal amylase release. Lactate dehydrogenase measurement after treatment of AR4-2J cells with beer for 24 hours indicated that the increase of amylase release was not due to cell membrane damage. Wine and hard liquor had no effect on basal amylase secretion neither diluted to the ethanol concentration of beer nor undiluted. In freshly isolated rat pancreatic acinar cells beer dose-dependently stimulated amylase secretion in a similar manner as in AR4-2J cells. Conclusions:, Our data demonstrate that beer dose-dependently increases amylase output. Since neither ethanol nor the other alcoholic beverages tested caused stimulation of amylase release, our findings indicate that nonalcoholic constituents specific for beer are responsible for this increase. These as yet unknown compounds have to be identified and considered in further studies of ethanol-induced pathological and functional changes of the pancreas. [source] Early, Selective, and Marked Loss of Sympathetic Nerves from the Islets of Biobreeder Diabetic RatsJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2003Q Mei To discover whether islet sympathetic nerves are damaged during the autoimmune destruction of islet B-cells, we immunostained sections of pancreas from Bio-Breeder (BB) diabetic rats, using antibodies against vesicular monoamine transporter 2 (VMAT2), a marker of sympathetic nerve terminals. We found a marked decrease in the VMAT2-positive fiber area in the islets of BB rats that had been diabetic for only 1,2 weeks compared with their nondiabetic controls. In contrast, there was no significant decrease in the VMAT2-positive fiber area in the exocrine pancreas in these early diabetic BB rats. Furthermore, streptozotocin-diabetic rats showed no decrease in VMAT2-positive fiber area in their islets compared with controls. The classical diabetic autonomic neuropathy (DAN) that eventually occurs in the heart was not present in BB diabetic rats at this early stage as evidenced by normal cardiac VMAT2 immunostaining and normal cardiac norepinephrine content. Also, in contrast to DAN, this islet neuropathy did not worsen with duration of diabetes. These data provide evidence of a heretofore unrecognized early sympathetic islet neuropathy (eSIN). Because eSIN occurs selectively in the islet, is rapid in onset, and is associated with autoimmune but not chemically induced diabetes, it is distinct from DAN in location, time course, and mechanism. [source] | |||||||||||||