Enzymhistochemische Diagnostik gastrointestinaler Motilitätsstörungen: Ein Laborleitfaden

Zusammenfassung: Die enzymhistochemischen Reaktionen für Acetylcholinesterase, Laktatdehydrogenase, Succinatdehydrogenase und Nitroxidsynthetase bilden gegenwärtig den Goldstandard zur histologischen Diagnose gastrointestinaler Motilitätsstörungen. Die Acetylcholinesterase-Reaktion stellt cholinerge Nervenfasernetze der Muscularis mucosae und Muscularis propria dar und zeigt deren Acetylcholinesterase-Aktivität an. Laktatdehydrogenase, Succinatdehydrogenase und Nitroxidsynthetase dienen komplementär der selektiven Darstellung der Nervenzellen des Plexus myentericus und submucosus. Diese enzymhistochemischen Techniken erfordern natives Gewebe, sodass der direkte Transport von der gastroenterologischen oder chirurgischen Abteilung zur Pathologie ohne Zeitverzug gewährleistet sein muss. Alternativ können die Biopsien auf Trockeneis an ein weiter entfernt gelegenes Institut versendet werden. Die hier beschriebene Laboranleitung ist über 4Jahrzehnte optimiert und verfeinert worden. Die im Labor optimierten enzymhistochemischen Reaktionen zeichnen sich durch ein höchstes Maß an Zuverlässigkeit und Reproduzierbarkeit aus. Insbesondere für eine interinstitutionelle Vergleichbarkeit der Resultate ist eine standardisierte Methodik unerlässlich. Entsprechend wird in dieser Anleitung eine detaillierte Darstellung der wichtigsten enzymhistochemischen Reaktionen zur Diagnostik gastrointestinaler Motilitätsstörungen gegebe

Functional significance of repressor element 1 silencing transcription factor (REST) target genes in pancreatic beta cells

Aims/hypothesis: The expression of several neuronal genes in pancreatic beta cells is due to the absence of the transcription factor repressor element 1 (RE-1) silencing transcription factor (REST). The identification of these traits and their functional significance in beta cells has only been partly elucidated. Herein, we investigated the biological consequences of a repression of REST target genes by expressing REST in beta cells. Methods: The effect of REST expression on glucose homeostasis, insulin content and release, and beta cell mass was analysed in transgenic mice selectively expressing REST in beta cells. Relevant target genes were identified in INS-1E and primary beta cells expressing REST. Results: Transgenic mice featuring a beta cell-targeted expression of REST exhibited glucose intolerance and reduced beta cell mass. In primary beta cells, REST repressed several proteins of the exocytotic machinery, including synaptosomal-associated protein (SNAP) 25, synaptotagmin (SYT) IV, SYT VII, SYT IX and complexin II; it impaired first and second phases of insulin secretion. Using RNA interference in INS-1E cells, we showed that SYT IV and SYT VII were implicated in the control of insulin release. Conclusions/interpretation: The data document the critical role of REST target genes in pancreatic beta cells. Specifically, we provide evidence that the downregulation of these genes is detrimental for the exocytosis of large dense core vesicles, thus contributing to beta cell dysfunction and impaired glucose homeostasi

Functional significance of repressor element 1 silencing transcription factor (REST) target genes in pancreatic beta cells

AIMS/HYPOTHESIS: The expression of several neuronal genes in pancreatic beta cells is due to the absence of the transcription factor repressor element 1 (RE-1) silencing transcription factor (REST). The identification of these traits and their functional significance in beta cells has only been partly elucidated. Herein, we investigated the biological consequences of a repression of REST target genes by expressing REST in beta cells. METHODS: The effect of REST expression on glucose homeostasis, insulin content and release, and beta cell mass was analysed in transgenic mice selectively expressing REST in beta cells. Relevant target genes were identified in INS-1E and primary beta cells expressing REST. RESULTS: Transgenic mice featuring a beta cell-targeted expression of REST exhibited glucose intolerance and reduced beta cell mass. In primary beta cells, REST repressed several proteins of the exocytotic machinery, including synaptosomal-associated protein (SNAP) 25, synaptotagmin (SYT) IV, SYT VII, SYT IX and complexin II; it impaired first and second phases of insulin secretion. Using RNA interference in INS-1E cells, we showed that SYT IV and SYT VII were implicated in the control of insulin release. CONCLUSIONS/INTERPRETATION: The data document the critical role of REST target genes in pancreatic beta cells. Specifically, we provide evidence that the downregulation of these genes is detrimental for the exocytosis of large dense core vesicles, thus contributing to beta cell dysfunction and impaired glucose homeostasis

AMMA-CATCH, a critical zone observatory in West Africa monitoring a megion in transition

International audienceWest Africa is a region in fast transition from climate, demography, and land use perspectives. In this context, the African Monsoon Multidisciplinary Analysis (AMMA)-Couplage de l'Atmosphere Tropicale et du Cycle eco-Hydrologique (CATCH) long-term regional observatory was developed to monitor the impacts of global change on the critical zone of West Africa and to better understand its current and future dynamics. The observatory is organized into three thematic axes, which drive the observation and instrumentation strategy: (i) analyze the long-term evolution of eco-hydrosystems from a regional perspective; (ii) better understand critical zone processes and their variability; and (iii) meet socioeconomic and development needs. To achieve these goals, the observatory has gathered data since 1990 from four densely instrumented mesoscale sites (similar to 10(4) km(2) each), located at different latitudes (Benin, Niger, Mali, and Senegal) so as to sample the sharp eco-climatic gradient that is characteristic of the region. Simultaneous monitoring of the vegetation cover and of various components of the water balance at these four sites has provided new insights into the seemingly paradoxical eco-hydrological changes observed in the Sahel during the last decades: groundwater recharge and/ or runoff intensification despite rainfall deficit and subsequent re-greening with still increasing runoff. Hydrological processes and the role of certain key landscape features are highlighted, as well as the importance of an appropriate description of soil and subsoil characteristics. Applications of these scientific results for sustainable development issues are proposed. Finally, detecting and attributing eco-hydrological changes and identifying possible regime shifts in the hydrologic cycle are the next challenges that need to be faced