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1
Martin, Franck. "Structural and functional studies of chromatin remodeling complex mamalian SWI / SNF". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ044.
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La chromatine est une structure dynamique régulée par différents mécanismes épigénétiques parmi lesquels le remodelage de la chromatine dépendant de l’ATP comme le SWI/SNF. Leur importance est telle que les mutations des protéines de remodelage de la chromatine sont fortement associées à plusieurs maladies dont le cancer. Par exemple les protéines BCL7, qui sont de nouvelles sous unité centrales récemment identifié du complexe SWI/SNF des mammifère, sont associées à différents types de cancers comme dans le Diffuse Large B-cell Lymphoma (DLBCL). Les informations sur les protéines BCL7 sont à ce jour très limitées. En utilisant des approches biochimiques et structurelles, ce projet vise à mieux comprendre la structure et la fonction de ces sous unités auxiliaires. Nous rapportons ici que les protéines se lient à l’acidique patch du nucleosome avec sa regions N-terminal qui comprend un motif d’ancrage arginines et que la mutation de l’une de ces arginines impacte directement la liaison au nucleosome. Nous apportons aussi une hypothèse sur la position au sein du complexe SWI/SNF de BCL7 qui interagit avec le module ARP et plus particulièrement avec ACTB par l'intermédiaire d'un motif 2W, et qu’elles sont directement des partenaires de liaisons avec BAF47. Nous avons aussi pu identifier qu’une fois sur les nucléosomes c’est BAF47 qui prend place sur l’acidique patch et l’hélice de BCL7A est déplacéChromatin is a dynamic structure regulated by various epigenetic mechanisms, including ATP-dependent chromatin remodeling such as SWI/SNF. Their importance is such that mutations in chromatin remodeling proteins are strongly associated with several diseases, including cancer. For example, BCL7 proteins, which are newly identified core subunits of the mammalian SWI/SNF complex, are associated with different types of cancer, such as Diffuse Large B-cell Lymphoma (DLBCL). To date, information on BCL7 proteins is very limited. Using biochemical and structural approaches, this project aims to better understand the structure and function of these auxiliary subunits. We report here that the proteins bind to the nucleosome with its N-terminal regions, which include an arginine anchoring motif, and that mutation of one of these arginines directly impacts binding to the nucleosome. We also hypothesize that the position within the SWI/SNF complex of BCL7, which interacts with the ARP module and more specifically with ACTB via a 2W motif, is directly linked to BAF47. We were also able to identify that once on the nucleosomes, BAF47 takes its place on the acidic patch and the BCL7A helix is displaced
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Malieieva, Galyna. "Les acides gynkgolique et niflumique sont les nouveaux modulateurs de récepteur à la glycine". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0030/document.
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Le récepteur à la glycine est un récepteur neuronal qui appartient à la famille des canaux ligand-dépendants «cys-loop». Avec le récepteur ionotrope GABA ils fournissent la neurotransmission inhibitrice rapide dans le SNC des vertébrés grâce à leur perméabilité sélective au Cl-. Les récepteurs à la glycine participent à différents processus physiologiques comprenant le contrôle de l'activité motrice, la respiration, la sensation de douleur inflammatoire, la perception des stimuli visuels et auditifs. Le développement de modulateurs efficaces des récepteurs à la glycine permettra un contrôle précis de leur activité, ce qui est particulièrement important dans le cas des pathologies des récepteurs à la glycine, comme l'hyperekplexie. En utilisant l'analyse électrophysiologique, la mutagenèse dirigée et l'expression de protéines spécifiques dans un système hétérologue, nous avons identifié les acides ginkgoliques et niflumiques comme nouveaux modulateurs de récepteurs de la glycine, caractérisé leur action sur différentes sous-unités du récepteur et déterminé les sites importants pour la potentialisation ou l'inhibition des récepteurs à la glycine par ces composés. Cette approche est très prometteuse et ouvre de nouvelles voies vers des futures actions thérapeutiquesGlycine receptor is a ligand-gated neuronal receptor that possesses an ion pore permeable for Cl- and represents an important component of inhibitory neurotransmission in CNS of vertebrates. Glycine receptors participate in the control of motor activity, respiration, inflammatory pain sensation, perception of visual and auditory stimuli. Development of efficient modulators of glycine receptors will allow a precise control of their activity, which is especially important in the case of glycine receptor pathologies, such as hyperekplexia. In the present work we have identified ginkgolic and niflumic acids as novel modulators of glycine receptors, characterized their action on different subunits of the receptor and determined the most probable sites of interaction of the compounds with glycine receptors
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Peverini, Laurie. "Conception et application de nouveaux outils photochimiques pour l’étude des récepteurs canaux P2X". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF061/document.
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Les récepteurs P2X (P2XR), activés par l’ATP, sont impliqués dans des rôles physiopathologiques. Leur fonctionnement est associé à différents états conformationnels. Le projet de thèse a mené à associer la synthèse organique et l’application de molécules photo-activables avec des techniques d’électrophysiologie patch-clamp, pour décortiquer les mouvements moléculaires de ces récepteurs et effectuer des relations structure-fonction, via trois stratégies : - La synthèse et application d’agrafes photo-isomérisables qui permet le photo-contrôle des P2XR et l’étude de mouvements - La synthèse et caractérisation d’un acide aminé (aa) photo-clivable pour étudier les implications de zones sur la fonction des P2XR via une photolyse - L’incorporation d’un aa non naturel dans les P2XR pour étudier des interactions et mouvements via un « photo-pontage ». Nous avons élucidé les mécanismes moléculaires responsables de la perméabilité des P2XR, récusé l’existence de l'état dilaté et identifié un cation organique physiologique pouvant les traverser. Nous avons aussi conçu un acide aminé photo-clivable pouvant mener à des études structure-fonction des P2XRP2X receptors are cationic ligand-gated ion channels, activated by extracellular ATP, involved in many physio-pathological roles. Their function is associated with different allosteric states. During this PhD, we have designed three new strategies, spanning photochemical organic synthesis and patch-clamp electrophysiology to elucidate the molecular mechanisms involved in these conformational states and to collect data in order to study structure-function relationships. - Synthesis and application of molecular tweezers, which allows the photo-control of P2X Rand the study of molecular motions - Synthesis and characterization of a photo-cleavable amino acid with the aim of incorporating it into P2XR and doing structure-function relationships - Incorporation of an unnatural amino acid for photo-crosslinking studies. We have been able to probe the molecular mechanism involved in large organic cations permeation of P2XR, to bring into question the dilated state and to identify a physiological cation that can flow through P2XR. We have also designed a photo-cleavable amino acid which could serve in the study of structure-function relationships
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Chatelier, Aurélien. "Modulation des performances cardio-respiratoires du bar européen (Dicentrarchus labrax) par l'apport d'acides gras alimentaires : une étude intégrée des effets cardiaques in vivo au courant calcique de type L des myocytes ventriculaires". La Rochelle, 2005. http://www.theses.fr/2005LAROS148.
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La qualité du régime alimentaire, et en particulier sa composition en acides gras, est un facteur environnemental émergeant en tant que source de diversité physiologique. En effet, de nombreux travaux montrent que la composition en acides gras de l'alimentation influence les performances cardiaques et métaboliques des organismes. Le cœur joue un rôle central dans l'adaptation des poissons à leur environnement en assurant et en régulant, les flux internes d'énergie et de matière. Dans le contexte de l'adaptation environnementale des individus et de l'évolution des espèces, la compréhension des origines de la variabilité interindividuelle et notamment de l'influence exercée par les acides gras sur le fonctionnement du système cardio-respiratoire est un élément important. L'objectif de ce travail réalisé sur le bar européen (Dicentrarchus labrax) a été d'étudier, à deux niveaux organisationnels (organe, cellule), les effets de la composition en acides gras de l'alimentation et des tissus sur les performances cardio-respiratoires mesurées au cours d'un effort musculaire et d'une épreuve d'hypoxie, l'activité des canaux calciques de type L des myocytes ventriculaires. Les bars ont été nourris avec trois alimentations enrichies soit huile de poissons (riche en acides gras n-3 poly-insaturés), soit en huile de colza (riche en acide oléique et linoléique) ou encore en huile de palme (riche en acides gras saturés). L'étude à l'échelle de l'animal entier, réalisée au moyen d'un respiromètre de type Brett, a permis de mettre en évidence une modification significative des performances cardio-respiratoires des bars en fonction de la composition en acides gras de l'alimentation. Une forte teneur en acide oléique dans l'alimentation et donc dans les tissus cardiaques est toujours associée à de meilleures performances cardiaques et métaboliques. Au cours de l'épreuve d'hypoxie, aucune différence ne fut mise en évidence entre les différentes alimentations. L'étude électrophysiologique du canal calcique de type L a été réalisée grâce à la technique du patch clamp en configuration " whole-cell ". Nos résultats ont révélé que la perfusion d'acide oléique, ainsi qu'une teneur élevée de cet acide gras dans les membranes, pouvait induire une inhibition de l'influx des ions calcium via le courant calcique de type L. Cette baisse n'est accompagnée d'aucune modification majeure des paramètres d'activation et d'inactivation du canal. De par ses caractéristiques morphofonctionnelles, le cœur est responsable de la limitation des performances métaboliques et natatoire des poissons. Au cours d'un effort musculaire intense, la diminution du niveau d'oxygénation du sang veineux (source principale d'oxygène du tissus myocardique) va conduire à une hypoxie à l'échelle des cardiomyocytes. Cette baisse de l'oxygénation du myocarde conduit à des dérèglements de l'homéostasie calcique responsables d'une élévation du calcium cellulaire et de l'apparition d'arythmies. Les résultats expérimentaux obtenus suggèrent que l'acide oléique, par son action inhibitrice sur le courant calcique de type L, permet de limiter les risques d'apparition de ces arythmies. Cet effet protecteur de l'acide oléique serait responsable des performances cardio-respiratoires et natatoires observées chez les animaux nourris avec le régime enrichi en huile de colzaDiet fatty acid composition is an environmental factor that is emerging as a significant source of physiological diversity. Heart plays a central role in fish adaptability to their environment. The objective of the study on the sea bass (Dicentrarchus labrax) was to investigate the effects of fatty acids on: cardio-respiratory performances during a swim test and a hypoxic test, L-type calcium channel activity of ventricular myocytes. Sea bass were fed with three different diets enriched in fish oil (n-3 poly-unsaturated fatty acid), canola oil (oleic acid) and palm oil (saturated fatty acid). The study carried out on the whole animal shows that diet and cardiac high level of oleic acid is associated with best cardiac and metabolic performances. The hypoxic test revealed no significant difference between the diets. Studies on L-type calcium channel revealed that both oleic acid perfusion and high membrane content of oleic acid induce a reduction in ventricular myocyte calcium influx. The heart may limit metabolic and swimming performance of fishes. During an intensive muscular challenge, this restriction is due to cardiac hypoxia which leads to a rise in intracellular calcium and to the appearance or cardiac arrhythmias. Results suggest that oleic acid, by decreasing cell calcium entry, limit cardiac arrhythmia occurrence. This protective effect could be responsible of differences observed during the swim test
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Mistry, Dineshkumar. "The vertebrate neuronal gamma-aminobutyric acid (GABAa) receptor and its modulation : a patch clamp study". Thesis, University of St Andrews, 1988. http://hdl.handle.net/10023/14452.
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Pressure application of gamma-aminobutyric acid (GABA) to mouse spinal and rat DBG neurones maintained in culture evoked transient membrane currents. Using the whole-cell patch clamp technique, these currents were shown to primarily involve the flow of Cl-. The GABA-evoked whole-cell currents in both types of neurones were reversibly suppressed by the GABAA antagonist bicuculline. The barbiturate phenobarbitone reversibly potentiated GABA-evoked whole-cell currents in mouse spinal neurones. Attempts to look at the unitary currents activated by GABA in outside-out patches, revealed spontaneous unitary currents. The I-V relationships of the spontaneous currents were linear and had a reversal potential of OmV in symmetrically distributed Cl solutions. Changing the monovalent cation concentrations on one or both sides of the membrane patch had no effect on the amplitude or the reversal potential of the spontaneous currents. Replacing some of the Cl- in the patch pipette with the impermeant anion SO42- shifted the reversal potential to more negative values. These spontaneous currents in both types of neurones were blocked by bath perfusion of bicuculline. GABA-activated unitary currents in outside-out patches, the main conductance state in both types of neurones was 30pS. However, GABA could occasionally also activate other conductance levels. Spontaneous Cl- currents did not occur in cell-attached patches from mouse spinal and rat DRG neurones, suggesting that the spontaneous events in the outside-out patches did not represent the activity of voltage dependent Cl- channels. Alphaxalone, a steroid anaesthetic, potentiated GABA-evoked whole cell currents in both spinal and DRG neurones. At high (muM) concentrations, pressure application of alphaxalone evoked a membrane Cl- current; this current was reversibly suppressed by blcuculline and potentiated by phenobarbitone. Pregnanolone (5beta-pregnane-3x-ol-20-one) a progesterone metabolite at low (nM) concentrations reversibly enhanced GABA currents in spinal neurones. Pregnanolone at higher concentrations pressure applied to spinal neurones had a weak direct agonist action on the GABAA receptor. Pregnanolone prolonged the burst duration of GABA-activated unitary currents in outside-out patches from spinal neurones. Some of the actions of the steroids on the GABAA receptor were very similar to the barbiturates, bemegride, a respiratory stimulant was formerly used clinically to counteract barbiturate poisoning in man. Experiments were conducted to see whether bemegride could be used as a specific barbiturate antagonist. Bemegride reduced phenobarbitone enhanced GABA currents in mouse spinal neurones. However, bemegride alone also reduced GABA and pentobarbitone evoked currants to a similar extent. This is suggestive of a noncompetitive action on the GABAA receptor, therefore it was not used to elucidate the site of action of steroids.
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Syme, C. A. "Patch-clamp studies on endothelial cell and chromaffin cell K'+ channels : effects of shear stress, membrane stretch and fatty acids". Thesis, University of Strathclyde, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298575.
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Tatu, Rigwed R. "Development and Characterization of aPoly (l-lactic acid)/ Poly (e-caprolactone) Self-Expanding Patch forFetoscopic Repair of Myelomeningocele". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535635832679162.
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Zieren, Jürgen. "Hernienreparationen mit Netzprothesen klinische und experimentelle Untersuchungen". Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2001. http://dx.doi.org/10.18452/13702.
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In einer prospektiv-randomisierten klinischen Studie zur Leistenhernienreparation wurde die konventionelle Shouldice Operation mit den spannungsfreien Verfahren durch Netzimplantation in endoskopischer (transabdominelle praeperitoneale Netzplastik, TAPP) und offener Technik (Plug und Patch Reparation; PP) verglichen. Bezogen auf das Hauptzielkriterium postoperative Schmerzen ergaben beide spannungsfreie Verfahren (TAPP, PP) signifikant guenstigere Ergebnisse als die Shouldice Operation. Bei vergleichbarer Komplikationsrate war die Dauer postoperativer Einschraenkungen bei den spannungsfreien Verfahren ebenfalls signifikant kuerzer als nach Shouldice Operation. Zur Verbesserung der fuer die spannungsfreie Reparation erforderlichen Netzimplantate wurde in einer Tierstudie versucht, die bislang durch Resorption ungenuegende mechanische Stabilitaet eines resorbierbaren Polyglycolsaeure-Netzes durch Zugabe von Fibrinkleber bzw. humanen thrombozytaeren Wachstumsfaktoren zu verbessern. Hierdurch gelang ein signifikanter Anstieg der mechanischen Stabilitaet, so daß in dem verwendeten Tiermodell keine Herniationen auftraten.In a prospective-randomized study conventional Shouldice operation was compared with tension-free procedures using mesh implantation in endoscopic (transabdominal preperitoneal mesh repair, TAPP) and open technique (Plug and patch repair; PP) for inguinal hernia repair. Regarding the mean end point postoperative pain both tension-free procedures (TAPP, PP) revealed significantly better results than Shouldice operation. Complications were comparable between the groups but duration of postoperative restrictions was significantly shorter after both tension-free procedures. To improve mesh quality for tension-free hernia repair an animal experiment was performed using a resorbable polyglycolic acid mesh. Despite good incorporation this mesh shows insufficient tensile strength due to absorption. Application of fibrin glue or platelet releasates significantly improve the mechanical stability of the repair protecting against herniation in this animal model.
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Facchin, Andrea. "New path for thermochemical-biological conversion with a power-to-material approach". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23117/.
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I sistemi termochimico-biologici si basano su due proprietà: la capacità dei processi termochimici di dissociare le macromolecole della biomassa producendo composti a basso peso molecolare, e l’abilità dei batteri di convertire substrati anche complessi in sostanze chimiche di valore. Questa tesi ha sviluppato un nuovo approccio metodologico per approfondire la possibilità di un accoppiamento diretto tra pirolisi e digestione anaerobica, allo scopo di produrre acidi grassi volatili (VFA), sinergicamente con l’utilizzo di idrogeno come fonte rinnovabile per aumentare il valore del prodotto finale. In primo luogo, è stata fatta un'ampia caratterizzazione del rendimento di COD e della composizione chimica dei prodotti di pirolisi che ha rivelato come più del 50% del COD della biomassa di partenza sia convogliato in sostanze chimiche biodisponibili. In secondo luogo, sono stati sviluppati tre reattori anaerobici a gocciolamento con diversi materiali di riempimento, incluso il biochar. I prodotti di pirolisi sono stati successivamente fermentati con e senza idrogeno, per valutarne, in via preliminare, la possibile conversione in VFA. I risultati suggeriscono che il biochar ha agito come promotore per la biotrasformazione dei prodotti di pirolisi in VFA, producendo una conversione del 35% rispetto al COD in input, mentre l'idrogeno ha dimostrato la capacità di stabilizzare le rese di VFA a catena lunga.
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Kacem, Hanana Houda. "Établissement de primocultures de cellules cardiaques de palourdes Ruditapes decussatus : étude des courants ioniques et des MAP Kinases après exposition des cellules à des xénoobiotiques". Brest, 2011. http://www.theses.fr/2011BRES2011.
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La nécessité d’évaluer l’impact des xénobiotiques du milieu aquatique sur les organismes, justifie la mise en place de nouveaux bioessais et de biomarqueurs afin d’identifier les risques sanitaires et mieux les prévenir. L’utilisation de méthodes alternatives à l’expérimentation animale, telles que les cultures de cellules, est préconisée en toxicologie. C’est dans ce contexte que des cultures primaires de cellules cardiaques de palourde Ruditapes decussatus ont été mises en place afin d’évaluer les effets de trois types de polluants du milieu marin un biocide, une phycotoxine et un herbicide. Les primocultures sont obtenues en routine et restent fonctionnelles in vitro pendant au moins un mois. Parmi les cellules, les cardiomyocytes, dont un certain nombre de caractéristiques électrophysiologiques ont pu être précisées par patch clamp, présentent un intérêt comme bioessai pour des applications en toxicologie. Les réponses cellulaires évaluées in vitro varient selon le polluant testé et de manière dose-dépendante. En particulier, l’étude des voies de signalisation MAP kinases (P38, JNK et ERK) se révèle intéressanteThe necessity to evaluate impact of xenobiotics from aquatic environment in marine organisms justifies the implementation of new bioassays and biomarkers to identify health risks for better prevention. The use of alternative methods to animal experiment, such as cell cultures, is recommended in toxicology. In this context, primary cultures of heart cells from clam Ruditapes decussatus was established and used to evaluate the effects of three types of pollutants from marine environment: a biocide, a phycotoxine and an herbicide. Primary cultures were routinely obtained and maintained functional in vitro for at least one month. Among cells, cardiomyocytes identified by electrophysiological properties after study by patch clamp presents an interest as bioassay for applications in toxicology. Cellular responses evaluated in vitro varie with the pollutant and are time and dose dependent. In particular, study of MAPK signaling pathways (P38, JNK and ERK) are of major interest
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Mazza, Alessia Zecca. "The calcium path across the plasma membrane Ca2+-ATPhase : a study by single amino acid mutations /". Zürich, 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13235.
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Ozhathil, Lijo Cherian. "A structural and functional insight into TMEM16B, a calcium-activated chloride channel". Doctoral thesis, SISSA, 2014. http://hdl.handle.net/20.500.11767/3921.
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TMEM16B, also known as anoctamin 2 has been recently identified as a calcium-activated chloride channel. It is expressed at the synaptic terminals of photoreceptors, in hippocampal cells, in the cilia of olfactory sensory neurons and in the microvilli of vomeronasal sensory neurons. TMEM16B, as its most known cousin TMEM16A, is activated both by calcium and voltage. When this thesis was started there was no available data correlating the gating function and protein structure in TMEM16B.
In our first manuscript, we show a coupling between calcium and voltage in TMEM16B activation. Primary sequence analysis did not show any canonical calcium binding sites nor S4-like dedicated voltage sensors. However, the first intracellular loop contains several negatively charged amino acids. We performed site directed mutagenesis at 367E, and 386EEEEE390 in the first intracellular loop and investigated their role in calcium or voltage dependence of TMEM16B. Either neutralizing or deleting these acidic residues strongly shifted the conductance-voltage relation towards more positive voltages without a significant effect on the apparent calcium sensitivity. Our findings indicate involvement of glutamic acids from the first intracellular loop in voltage dependent activation of TMEM16B, and provides an initial structure-function study for this channel.
In our second manuscript, we focused on understanding the effect of permeant anions on TMEM16B activation. Our results show TMEM16B is poorly selective among anions and has a permeability sequence of SCN- > I- > NO3- > Br- > Cl- > F- > gluconate. The channel kinetics also shows dependence on the permeant anion, with more permeable anions, such as SCN-, causing a much slower activation and deactivation kinetics than Cl-. Moreover, SCN- facilitated the channel activation by
lowering the half-maximal concentration of calcium required for opening the channel and shifting the conductance-voltage relation towards less positive voltages. From this work we report the existence of a crosstalk between calcium, voltage and permeant anion in TMEM16B activation.
Furthermore, we looked for a compound that could modulate the function of TMEM16B. We found that anthracene-9-carboyxlic acid, one of the traditional calcium-activated chloride channel blockers is very interesting since it had multiple effects on TMEM16B. In our third manuscript we report the block by A9C as voltage and concentration dependent, with maximal inhibition at positive voltages. Surprisingly, A9C also potentiated the current at intermediate concentrations and negative voltages. However, anthracene-9-methanol (A9M), a non-charged analog of A9C, completely abolished the voltage dependent inhibition and the potentiation effect seen with A9C. Both A9C and A9M had much slower current kinetics. This indicates the requirement of negative charge of A9C for its voltage dependent block of outward currents and potentiation of inward currents.
In summary, the studies included in this thesis reveal a complex coupling between calcium, voltage, and permeant anion in TMEM16B activation. The identification of a compound have contrasting effects on the channel activation, provides a new tool for future structure-function studies on this channel.
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Breeze, Liam J. "Cav1.2 pore structure using the substituted-cysteine accessibility method /". Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2006.
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Thesis (Ph.D. in Neuroscience) -- University of Colorado at Denver and Health Sciences Center, 2006.Typescript. Includes bibliographical references (leaves 108-118). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;
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Manzini, Ivan. "Diversity of transduction mechanisms in receptor neurons of the main olfactory epithelium in Xenopus laevis tadpoles". Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=975110926.
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Biet, Michaël. "Rôle et implication du courant sodique cardiaque dans la genèse de phénomènes arythmogéniques en conditions physiopathologiques". Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6054.
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Le potentiel d’action cardiaque est un phénomène électrique finement régulé par des modifications du voltage membranaire engendré par l’ouverture de différents canaux ioniques (sodium, calcium, chlore et potassium) présents à la surface des cardiomyocytes. Les transferts d’ions, de part et d’autre de la membrane via ces canaux, génèrent des courants pouvant être mesurés par la technique de patch clamp. L’activité électrique cardiaque est donc la résultante d’un équilibre de différents flux d’ions qui peut également être modulé par les systèmes sympathique et parasympathique afin de permettre l’adaptation du rythme cardiaque.
Le courant sodique (I[indice inférieur Na]) est responsable de l’initiation des potentiels d’action (PA) et module sa durée. Il joue donc un rôle prépondérant dans l’excitabilité cardiaque et la conduction de l’influx électrique. De par ce fait, une modification des propriétés biophysiques d’I[indice inférieur Na] lors de conditions physiopathologiques peut engendrer des troubles du rythme. I[indice inférieur Na] est divisé en phases rapide (I[indice inférieur Na] pic) et soutenue (I[indice inférieur NaL]) qui interviennent respectivement dans l’excitabilité et la durée d’un PA (phase de plateau). De plus, notre laboratoire a démontré que les canaux sodiques de types cardiaque ([indice inférieur Na]V1.5) et neuronaux (n[indice inférieur Na]Vs) contribuent à I[indice inférieur Na]. Chacun se différencie par leurs propriétés biophysiques, leurs contributions à I[indice inférieur Na] (pic et soutenu) ainsi qu’à leurs sensibilités à la tétrodotoxine (TTX).
Nous avons étudié les effets précoces d’un diabète de type II, de l’exposition in-utero à la nicotine des nouveau-nés, de l’épilepsie et de l’ischémie sur les propriétés biophysiques du courant sodique cardiaque I[indice inférieur Na] responsable de l’impulsion électrique menant au battement cardiaque. Ces pathologies ont comme point commun l’apparition de troubles du rythme cardiaque tels que des bradycardies, des troubles de conduction menant parfois à des blocs auriculo-ventriculaires (BAV), des insuffisances cardiaques ou encore des problèmes d’excitabilité pouvant tous être reliés au courant sodique.
Nos résultats montrent que toutes ces conditions physiopathologiques altèrent les propriétés du courant sodique en augmentant l’amplitude du courant I[indice inférieur Na] (diabète, exposition in-utero à la nicotine, épilepsie), l’excitabilité (diabètes, exposition in-utero à la nicotine, épilepsie) ou en augmentant le taux de participation des nNaVs à I[indice inférieur NaL] (épilepsie, ischémie). Nos données concordent avec la littérature et les observations cliniques et permettent d’expliquer en partie l’apparition de ces anomalies de troubles du rythme survenant chez les personnes atteintes de ces pathologies.
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Frenal, Karine. "Caractérisation structurale et fonctionnelle de TgDRE : une enzyme de réparation de l' ADN du parasite Toxoplasma gondii". Paris 6, 2006. http://www.theses.fr/2006PA066031.
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Coussin, Frédéric. "Identification et rôle des récepteurs-canaux à la ryanodine dans la signalisation calcique intracellulaire des myocytes vasculaires : approche par microscopie confocale et oligonucléotides antisens". Bordeaux 2, 2000. http://www.theses.fr/2000BOR28801.
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Rudolph, Tim Christoph [Verfasser], Lothar [Akademischer Betreuer] Mörl, Waltraud [Akademischer Betreuer] Kahle y Gerald [Akademischer Betreuer] Warnecke. "Model-based stochastic optimization of palm oil deodorization via Short-Path-Distillation towards 3-MCPD fatty acid ester formation and major oil quality parameters / Tim Christoph Rudolph ; Lothar Mörl, Waltraud Kahle, Gerald Warnecke". Magdeburg : Universitätsbibliothek, 2016. http://d-nb.info/1125507993/34.
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Rudolph, Tim Christoph Verfasser], Lothar [Akademischer Betreuer] [Mörl, Waltraud [Akademischer Betreuer] Kahle y Gerald [Akademischer Betreuer] Warnecke. "Model-based stochastic optimization of palm oil deodorization via Short-Path-Distillation towards 3-MCPD fatty acid ester formation and major oil quality parameters / Tim Christoph Rudolph ; Lothar Mörl, Waltraud Kahle, Gerald Warnecke". Magdeburg : Universitätsbibliothek, 2016. http://d-nb.info/1125507993/34.
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Ito, Vanessa Mayumi. "Concentração de tocoferois e fitoesterois a partir do destilado desodorizado de oleos vegetais atraves do processo de destilação molecular". [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267393.
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Orientadores: Maria Regina Wolf Maciel, Cesar Benedito BatistellaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Resumo: Os tocoferóis e fitoesteróis são componentes minoritários presentes em plantas e óleos vegetais. Os tocoferóis apresentam atividades vitamínicas e propriedades antioxidantes. A vitamina E é composta por 4 tocoferóis (a, b, g e d) e 4 tocotrienóis (a, b, g e d). Os fitoesteróis possuem propriedades anticolesterolêmica e anticarcinogênicas. Uma das principais fontes de tocoferóis e fitoesteróis são os destilados desodorizados de óleos vegetais. Os destilados desodorizados são constituídos de ácidos graxos, triglicerídeos, fitoesteróis, hidrocarbonetos, aldeídos, cetonas, tocoferóis, dentre outros. Neste trabalho foram estudados dois tipos de destiladores moleculares: centrífugo e de filme descendente (agitado). Os destilados desodorizados de óleo de soja, canola e girassol foram processados no destilador molecular de filme descendente. A recuperação de ácidos graxos livres em função da razão entre as vazões das correntes de destilado e de resíduo apresentou o mesmo perfil para os três destilados desodorizados estudados. O destilado desodorizado de óleo de soja, abundante no Brasil, foi processado no destilador molecular centrífugo. O processo de destilação centrífugo foi estudado tanto experimentalmente quanto por simulação. Foi realizado um planejamento fatorial visando analisar o comportamento das variáveis (temperatura do evaporador e vazão de (alimentação). Observou-se que ocorre uma maior eliminação de ácidos graxos livres a altas temperaturas do evaporador e baixas vazões de alimentação. Tanto o processo de destilação molecular de filme descendente quanto o centrífugo duplicaram a concentração inicial de tocoferóis. Através do processo de destilações sucessivas triplicou-se a concentração de tocoferóis e, com destilações sucessivas seguidas de uma etapa de cristalização, quaduplicou-se a concentração de tocoferóis em relação à concentração original
Abstract: Tocopherols and phytosterols are minority compounds present in vegetables oils. Tocopherols show vitaminic activities and antioxidant properties. Vitamin E is composed by four tocopherols (a, b, g and d) and four tocotrienols (a, b, g and d). The phytosterols have anticholesterolemic and anticarcinogenic properties. The main natural sources of tocopherols and phytosterols are the vegetable oil deodorized distillate (VODD). The deodorized distillates are composed by fatty acids, acylglycerols, sterols, hydrocarbons, aldehydes, ketones and tocopherols. In this work, two kinds of molecular distillation equipments were studied: centrifugal and falling film (wiped). The soybean, canola and sunflower oil deodorized distillates were carried out at falling film molecular distilator. The free fatty acids recovery in function of the Distillation mass/Residue mass ratio shows similar behavior to the three VODDs. Soybean oil deodorized distillate, abundant in Brazil, was chosen to be processed in the centrifugal molecular distiller. This centrifugal molecular distillation process was studied experimental and simulated. The factorial design was carried out to analyze the variable behavior (evaporator temperature and feed flow rate). The free fatty acids elimination occurs at higher evaporator temperatures and lower feed flow rate. The falling film and centrifugal molecular distillation process duplicates the tocopherol concentration. Through successive distillations, the tocopherol concentration was three times higher and with the crystallization, the tocopherol concentration was four times in relation to the original concentration
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
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Bertram, Janet. "Effects of cow urine and its constituents on soil microbial populations and nitrous oxide emissions". Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1334.
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New Zealand’s 5.3 million strong dairy herd returns approximately 106 million litres of urine to pasture soils daily. The urea in that urine is rapidly hydrolysed to ammonium (NH₄⁺), which is then nitrified, with denitrification of nitrate (NO₃⁻) ensuing. Nitrous oxide (N₂O), a potent greenhouse gas (GHG), is produced via nitrification and denitrification, which are enzyme-catalysed processes mediated by soil microbes. Thus microbes are linked intrinsically to urine patch chemistry. However, few previous studies have investigated microbial dynamics in urine patches. Therefore the objective of these four experiments was to investigate the effects on soil microbial communities of cow urine deposition. Methods used included phospholipid fatty acid (PLFA) analyses of microbial community structure and microbial stress, dehydrogenase activity (DHA) assays measuring microbial activity, and headspace gas sampling of N₂O, ammonia (NH₃) and carbon dioxide (CO₂) fluxes. Experiment 1, a laboratory study, examined the influence of soil moisture and urinary salt content on the microbial community. Both urine application and high soil moisture increased microbial stress, as evidenced by significant changes in PLFA trans/cis and iso/anteiso ratios. Total PLFAs and DHA showed a short-term (< 1 week) stimulatory effect on microbes after urine application. Mean cumulative N₂O-N fluxes were 2.75% and 0.05% of the nitrogen (N) applied, from the wet (70% WFPS) and dry (35% WFPS) soils, respectively. Experiment 2, a field trial, investigated nutrient dynamics and microbial stress with plants present. Concentrations of the micronutrients, copper, iron and molybdenum, increased up to 20-fold after urine application, while soil phosphorus (P) concentrations decreased from 0.87 mg kg ⁻¹ to 0.48 mg kg⁻¹. Plant P was also lower in urine patches, but total PLFAs were higher, suggesting that microbes had utilised the available nutrients. Microbial stress again resulted from urine application but, in contrast to experiment 1, the fungal biomass recovered after its initial inhibition. Studies published during the course of this thesis reported that hippuric acid (HA) and its hydrolysis product benzoic acid (BA) significantly reduced N₂O-N emissions from synthetic cow urine, thus experiment 3 investigated this effect using real cow urine. Cumulative N₂O-N fluxes were 16.8, 5.9 and 4.7% of N applied for urine (U) alone, U+HA and U+BA, respectively. Since NH₃-N volatilisation remained unchanged, net gaseous N emissions were reduced. Trends in total PLFAs and microbial stress were comparable to experiment 1 results. Experiment 4 studied HA effects at different temperatures and found no inhibition of N₂O-N fluxes from HA-amended urine. However, mean cumulative N₂O-N fluxes were reduced from 7.6% of N applied at 15–20°C to 0.2% at 5–10°C. Total cumulative N emissions (N₂O-N + NH₃-N) were highest at 20°C (17.5% of N applied) and lowest at 10°C (9.8% of N applied). Microbial activity, measured as potential DHA, increased with increasing temperature. This work has clearly shown that the stimulation and inhibition of the soil microbial community by urine application are closely linked to soil chemistry and have significant impacts not only on soil nutrient dynamics but also on N₂O-N emissions and their possible mitigation.
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Urio, Ricardo de Prá. "Cromatografia a líquido por injeção sequencial para a determinação de herbicidas triazínicos e metabólitos da atrazina explorando o uso de cela de longo caminho óptico e monitoramento on-line em estudos de adsorção". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-31082011-143740/.
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Estudou-se o emprego da Cromatografia a Líquido por Injeção Seqüencial (SIC) explorando o uso de uma cela de longo caminho óptico com guia de onda (LCW) de 100 cm para a melhora dos limites de detecção (LOD) e quantificação (LOQ) na determinação de atrazina (ATR), propazina (PRO) e simazina (SIM). Para isto, utilizou-se uma fase móvel com composição de 44:56 (v v-1) metanol : tampão acetato de amônio 1,25 mM, pH 4,7, coluna monolítica e a detecção espectrofotométrica em 238 nm. Obtiveram-se valores de LOD e LOQ, respectivamente, de 1,76 e 5,86 µg L-1 para ATR, 4,51 e 15 µg L-1 para PRO e 2,25 e 7,5 µg L-1 para SIM. Com o emprego da cela de longo caminho óptico os valores de LOD ficaram abaixo dos recomendados pela US-EPA, que permite para águas potáveis uma concentração de 3 µg L-1 para ATR, 4 µg L-1 para SIM e 10 µg L-1 para PRO. Realizaram-se estudos de adsorção de SIM, PRO e ATR e seus metabólitos desisopropilatrazina (DIA), desetilatrazina (DEA) e 2-hidroxiatrazina (HAT) em solo, ácido húmico e solo modificado com ácido húmico. Para isso foi utilizado um sistema de monitoramento on-line composto por um filtro tangencial e uma bomba peristáltica para circulação da suspensão. Foram realizados estudos cinéticos em duas etapas e, em ambas, foi utilizado um mix dos compostos com concentração inicial de 1,0 mg L-1 e gradiente de eluição passo a passo para a separação dos compostos utilizando três fases móveis com composições de 15 ou 28, 40 e 50% (v v-1) metanol : tampão acetato de amônio 1,25 mM pH 4,7. Na primeira etapa o tempo de contato entre triazinas e adsorventes foi de 90 min. Na segunda etapa foi utilizado apenas o solo como adsorvente e o tempo de contato foi de 24 h. Para a primeira etapa do estudo só foi possível aplicar modelo cinético de pseudo-segunda ordem, o qual permitiu estimar os valores de massa adsorvida de triazina por massa de adsorvente, sendo que o ácido húmico é o material com maior capacidade adsortiva (1470 ± 43µg g-1 para DIA a 2380 ± 51 µg g-1 para PRO). O composto mais adsorvido em solo é PRO (26,5 ± 0,1 µg g-1). A presença de ácido húmico no solo aumentou a adsorção de ATR (de 19,4 ± 0,7 para 23 ± 2 µg g-1), de HAT (10,9 ± 0,7 para 18 ± 2 µg g-1) e de PRO (26,5 ± 0,7 para 29,8 ±0,2 µg g-1), mas diminuiu a adsorção de SIM e não afetou DIA e DEA. No estudo com tempo de contato de 24 h foi possível aplicar modelos de pseudo-primeira e segunda ordem. Os resultados obtidos confirmaram a maior adsorção de PRO, seguidos da ATR. HAT, SIM, DEA e DIA apresentaram as menores taxas de adsorção em solo, sendo que os dois últimos apresentaram uma tendência de dessorção após 4 h de contato, tendo maior potencial de lixiviação para corpos d\'água próximos aos locais de aplicação.This work describes the use of Sequential Injection Liquid Chromatography (SIC) coupled to a long path length optical flow cell with 100 cm long Liquid Core Waveguide (LCW) to improve the limits of detection (LOD) and quantification (LOQ) for determination of atrazine (ATR), propazine (PRO) and simazine (SIM). Separation was achieved with a mobile phase composition of 44:56 (v v-1) methanol:1.25 mM ammonium acetate buffer, pH 4.7, monolithic column and spectrophotometric detection at 238 nm. The values of LOD and LOQ were, respectively, 1.76 and 5.86 µg L-1 for ATR, 4.51 and 15 µg L-1 for PRO and 2.25 and 7.5 µg L-1 for SIM. The LOD values achieved with the employment of long optical path cell were lower than those recommended by US-EPA, which allows for drinking water, maximum concentration levels of 3 µg L-1 for ATR, 4 µg L-1 for SIM and 10 µg L-1 for PRO. Adsorption of SIM, PRO and ATR, as well as their metabolites desisopropylatrazine (DIA), desethylatrazine (DEA) and 2-hidroxyatrazine (HAT) on soil, humic acid and soil modified with humic acidic was studied. An on-line monitoring system was assembled, composed of a tangential filter and a peristaltic pump for circulation of the suspension. Kinetic studies were carried out in two steps, and in both, it was used a mix of compounds with initial concentration of 1,0 mg L-1 and a stepwise gradient elution for separation of the compounds using three mobile phases with compositions of 15 or 28, 40 and 50% (v v-1) methanol: 1.25 mM ammonium acetate buffer, pH 4.7. In the first step the contact time between triazines and adsorbents was 90 minutes. In a second study made only with soil, the contact time was 24 h. Data obtained in the first stage of the study was only fitted to pseudo-second order kinetic equation, which allowed one to estimate the values of the adsorbed mass of triazine per mass of adsorbent. Humic acid was the material with higher adsorptive capacity (from 1470 ± 43 µg g-1 for DIA to 2380 ± 50 µg g-1 for PRO). In soil, PRO exhibited the highest adsorption (26.5 ± 0.1 µg g-1). The presence of humic acid in the soil increased adsorption of ATR (19.4±0.7 to 23±2 µg g-1), HAT (10.9 ± 0.7 to 18 ± 2 µg g-1) and PRO (26.5 ± 0.7 to 29.8 ± 0.2 µg g-1), but decreased adsorption of SIM, not affecting DIA and DEA. In the study with contact time of 24 h, it was possible apply pseudo-first and pseudo-second order equations for SIM, ATR and PRO. The results confirmed the greatest adsorption of PRO, followed by ATR. HAT, SIM, DEA and DIA had low rates of adsorption on soil, the latter two showed a trend of desorption after 4 h of contact, having the greatest potential for leaching to water bodies near to the places of application.
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Wong, Ee Nuan y 黃奕鑾. "Gellan gum/Hyaluronic acid carrier Clioquinol or 5-fluorouracil as the treatment patch of oral cancer". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/65685177401355788013.
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Kang, Pei-Leun y 康沛倫. "Hyaluronic Acid/Collagen/Mesenchymal Stem Cells Cardiomyocyte-like Cells Cardiac Patch on the Restoration of Injured Myocardium". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/55251440463832049067.
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博士國立臺灣大學
醫學工程學研究所
102
As well known, cardiomyocytes and neural cells are un-proliferative cells in human. Especially, when the cardiomyocytes damaged, necrotized and loosed its function, the heart is difficult to recover to its original function. To date, in clinical practice, the remedy of this damaged heart is by heart transplantation or heart assist devices. Besides, by implanting regenerative cardiomyocytes into the defect area is now acquiring more attentions from many recent researchers. 5-azacytidine is used to differentiate the mesenchymal stem cells (MSCs) to cardiomyocyte-like cells in these researches. These cardiomyoctye-like cells reveal the spontaneous heart-beat behaviors and with action potentials as normal cardiomyocytes. Type I collagen is the main composition of extracellular matrix. It provides many cellular functions, including providing scaffolds for cells adhesion, migration, differentiation and proliferation. Hyaluronic acid, also possesses biocompatible and biodegradable properties, and used to prepare cell-cultural substrates in tissue engineering applications. The aims (or works) of this study are to prepare 3-D mimetic scaffold (cardiopatch) which be able to provide a natural like micro environment for MSCs growth, to evaluate a chemical stimulant which act as a signal transduction factor, 5-azacytidine is added into the scaffold or medium to stimulate MSCs differentiate to the cardiomyocytes, and to establish animal model with myocardial injury. According to the analysis of water content, porosity and mechanical properties of collagen/hyaluronan composite scaffold, the group composite scaffold (collagen I : HA of 7:1.5) has the maximum elongation. The effect of 5-azacytidine used to induce differentiation of mesenchymal stem cells into cardiomyocyte was positively confirmed by real-time PCR. The results showed that mesenchymal stem cells seeded in composite scaffold expressed higher value of cardiomyocyte specific genes (such as cTnI, β-MHC and α-actin) than the group of cells without using any scaffold but only 5-azacytidine. During the buildup of animal model with myocardial damages, operation was performed to suture the left anterior descending artery and it resulted dark red color change on the distal end of myocardium, biopsy observation also reported that part of myocardium have been replaced with fibroblast with mesenchymal cells alignment or distribution. This proves that by suturing the left anterior descending artery can cause damages to myocardium. The animal study demonstrated that collagen/HA composite scaffolds have the potential for cardiac regeneration applications.
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Daniels, Bryan. "Modulation of ionotropic glutamate receptors in retinal neurons by the amino acid D-serine". 2011. http://hdl.handle.net/10222/13296.
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D-Serine is regarded as an obligatory co-agonist required for the activation of NMDA-type glutamate receptors (NMDARs). In the retina D-serine and a second NMDAR coagonist, glycine, are present at similar concentration and the cells that produce and release them are in close apposition. This arrangement allows for an abundant supply of coagonists and under certain conditions the NMDAR coagonist binding site could be saturated. There is also evidence suggesting that D-serine can act in an inhibitory manner at AMPA/kainate-type glutamate receptors (GluRs). Glutamate receptor activation can lead to direct and indirect elevation of intracellular calcium (Ca2+) concentration ([Ca2+]i). Therefore, in this thesis, I predominantly used Ca2+ imaging techniques to study the effect of D-serine on GluR activation in the mammalian retina. I first describe a novel method I developed to load retinal cells with Ca2+ indicator dye using electroporation and show that retinas remain viable and responsive following electroporation. This technique was used to explore the excitatory role of D-serine at NMDARs and its potential inhibition of AMPA/kainate receptors using cultured retinal ganglion cells (RGCs) and isolated retina preparations. Using cultured RGCs I demonstrated that D-serine and glycine enhance NMDAR-mediated Ca2+ responses in a concentration-dependent manner and are equally effective as coagonists. In isolated retinas I showed that D-serine application enhanced NMDA-induced responses consistent with sub-saturating endogenous coagonist concentration. Degradation of endogenous D-serine reduced NMDAR-mediated Ca2+ responses supporting the contribution of this coagonist to NMDAR activation in the retina. Using imaging and two different electrophysiological approaches, I found that D-serine reduced AMPA/kainate receptor-mediated responses in cultured RGCs and isolated retinas at concentrations that are saturating at NMDARs. Antagonist experiments suggest that the majority of inhibition is due to D-serine acting on AMPA receptor activity. Degradation of endogenous D-serine enhanced AMPA/kainate-induced responses of some cells in isolated retina suggesting that, under these conditions, D-serine concentration may be sufficient to inhibit AMPA receptor activity. Overall, the work in this thesis illustrates the utility of electroporation as a method to load Ca2+-sensitive fluorescent dyes into retinal cells and highlights the potential role for D-serine as a modulator of ionotropic GluRs in the CNS.
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Aromataris, Edoardo Claudio. "Pharmacology of the CIC-1 chloride channel". 2009. http://hdl.handle.net/2440/58973.
Texto completoResumen
Clinical studies reported side effects of muscular spasms and muscle stiffness following the administration of clofibrate, a drug once used to treat hyperlipidaemia in patients. Experiments with clofibrate and its analogues in animal models showed it produced these myotonic symptoms in muscle by reducing the chloride conductance of the muscle membrane. The effects of 2-(4-chlorophenoxy)propionic acid, an analogue of clofibric acid, was assessed on the rat ClC-1 channel (rClC-1). Racemic 2-(4-chlorophenoxy)propionic acid shifted the voltage dependence of rClC-1 activation to more depolarising potentials, a mechanism accounting for myotonic symptoms previously reported. Experiments with resolved enantiomers revealed that the effects recorded were due exclusively to S-(–) 2-(4- chlorophenoxy)propionic acid. The R-(+) enantiomer was ineffective at the concentrations tested. Further experiments with the compound at differing Cl- concentrations in the extracellular solution suggested that S-(–) 2-(4-chlorophenoxy)propionic acid altered the gating of ClC-1 by decreasing the affinity of the binding site where Cl- normally acts to ‘gate’ the channel. Similarities in the effects reported for most dominant mutations in the CLCN1 gene that lead to myotonia congenita and 2-(4-chlorophenoxy)propionic acid prompted experiments that introduced these point mutations in the human ClC-1 (hClC-1) gene to compare their mode of action to that of the drug. These mutations, F307S and A313T, predominantly altered the slow, or common, gate of the channel. Conversely, the effect of 2-(4-chlorophenoxy)propionic acid was predominantly on the fast gating process of hClC-1. A macroscopically similar effect therefore, can be produced by two different modes of action. Results suggested that both drug and mutations exert their action by affecting the transition of the channel from its closed to open state subsequent to Cl- binding. Investigation of the interaction between rClC-1 gating and a further 25 compounds structurally related to clofibric acid identified a number of compounds effective at shifting the open probability of fast gating to depolarising potentials. Fewer were identified that influence slow gating. Some compounds affected both gating processes, however, none were identified which influenced slow gating alone. Ability to displace the voltage dependent activation of the fast gate appeared to depend largely on the lipophilicity of the molecules tested, indicating the importance of hydrophobic interactions between drug and channel protein.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474724
Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2009
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Yu, Ya-Hui y 游雅惠. "Application of Flush Response to Niacin Skin Patch in Schizophrenia Research: Comparing Visual Rating with Infrared Thermography and Their Relations to Fatty Acids Levels in Blood". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/90272977649091262130.
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碩士國立臺灣大學
流行病學與預防醫學研究所
99
Background: Attenuated niacin-induced flush response, a potential endophenotype for schizophrenia, has been postulated to involve a prostaglandin-related microvasodilation pathway where arachidonic acid or other fatty acids may play important roles. However, the correlations between the flush response and the implicated biochemical indexes remained incoherent, either because of different ways in giving niacin challenge test or in the evaluation of response. Alternatively measuring the raising temperature accompanying the niacin-induced flush might serve as an tool to assess the niacin-induced flush response. Objectives: This study aimed to: 1) evaluate the applicability of infrared thermography in measuring the niacin-induced flush response, and 2) examine the relations of the flush magnitude to fatty acids levels in blood. Methods: For the first aim, a pilot study of two groups of subjects were used to clarify the correlation between objectively measured temperature and visually rated flush score, whereas for the second aim another independent sample of psychiatric inpatients as well as healthy controls were used to explore the correlation between temperature, flush and fatty acids levels in red blood cells (RBCs) as well as in plasma. Three concentrations of niacin skin test with forty minute observation by visual rating method and infrared thermography method was performed in the sample of pilot study (31 patients with schizophrenia and 32 normal controls). On the other hand, niacin skin test with fifteen minute observation using both methods and blood fatty acids analysis were performed in the sample of biochemical study (9 patients with schizophrenia, 6 patients with bipolar disorder, and 15 normal controls). Fatty acids compositions of RBC and plasma were analyzed using gas chromatography. Results: Visual rating score method showed group difference in 0.001M while thermography method did not reveal group difference in all concentration and times. The correlations between these two methods were weak. Subjects of biochemical sample were re-grouped as non-flushers versus flushers on the basis of the flush score for 0.01M at 5 minute. The RBC and plasma levels of n-6 fatty acids in non-flushers tended to be lower than the corresponding ones of flushers and the RBC level of EPA was significantly higher in non-flushers than flushers. Conclusions: This study demonstrated that in measuring the niacin-induced flush response the visual rating method is better in discriminating schizophrenia patients from normal controls than the infrared thermography-based temperature rating. Furthermore, our results indicate that non-flushers tended to have lower levels of n-6 fatty acids but higher EPA levels than flushers. Future investigation is warranted to further explore the physiological abnormalities associated with the attenuated flush response in schizophrenia patients.
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Aromataris, Edoardo Claudio. "Pharmacology of the CIC-1 chloride channel". Thesis, 2009. http://hdl.handle.net/2440/58973.
Texto completoResumen
Clinical studies reported side effects of muscular spasms and muscle stiffness following the administration of clofibrate, a drug once used to treat hyperlipidaemia in patients. Experiments with clofibrate and its analogues in animal models showed it produced these myotonic symptoms in muscle by reducing the chloride conductance of the muscle membrane.
The effects of 2-(4-chlorophenoxy)propionic acid, an analogue of clofibric acid, was assessed on the rat ClC-1 channel (rClC-1). Racemic 2-(4-chlorophenoxy)propionic acid shifted the voltage dependence of rClC-1 activation to more depolarising potentials, a mechanism accounting for myotonic symptoms previously reported. Experiments with resolved enantiomers revealed that the effects recorded were due exclusively to S-(–) 2-(4- chlorophenoxy)propionic acid. The R-(+) enantiomer was ineffective at the concentrations tested. Further experiments with the compound at differing Cl- concentrations in the extracellular solution suggested that S-(–) 2-(4-chlorophenoxy)propionic acid altered the gating of ClC-1 by decreasing the affinity of the binding site where Cl- normally acts to ‘gate’ the channel.
Similarities in the effects reported for most dominant mutations in the CLCN1 gene that lead to myotonia congenita and 2-(4-chlorophenoxy)propionic acid prompted experiments that introduced these point mutations in the human ClC-1 (hClC-1) gene to compare their mode of action to that of the drug. These mutations, F307S and A313T, predominantly altered the slow, or common, gate of the channel. Conversely, the effect of
2-(4-chlorophenoxy)propionic acid was predominantly on the fast gating process of hClC-1. A macroscopically similar effect therefore, can be produced by two different modes of action. Results suggested that both drug and mutations exert their action by affecting the transition of the channel from its closed to open state subsequent to Cl- binding.
Investigation of the interaction between rClC-1 gating and a further 25 compounds structurally related to clofibric acid identified a number of compounds effective at shifting the open probability of fast gating to depolarising potentials. Fewer were identified that influence slow gating. Some compounds affected both gating processes, however, none were identified which influenced slow gating alone. Ability to displace the voltage dependent activation of the fast gate appeared to depend largely on the lipophilicity of the molecules tested, indicating the importance of hydrophobic interactions between drug and channel protein.Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2009
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Chamberlain, S. E., I. M. Gonzàlez-Gonzàlez, K. A. Wilkinson, F. A. Konopacki, Sriharsha Kantamneni, J. M. Henley y J. R. Mellor. "SUMOylation and phosphorylation of GluK2 regulate kainate receptor trafficking and synaptic plasticity". 2012. http://hdl.handle.net/10454/5911.
Texto completoResumen
NoPhosphorylation or SUMOylation of the kainate receptor (KAR) subunit GluK2 have both individually been shown to regulate KAR surface expression. However, it is unknown whether phosphorylation and SUMOylation of GluK2 are important for activity-dependent KAR synaptic plasticity. We found that protein kinase C-mediated phosphorylation of GluK2 at serine 868 promotes GluK2 SUMOylation at lysine 886 and that both of these events are necessary for the internalization of GluK2-containing KARs that occurs during long-term depression of KAR-mediated synaptic transmission at rat hippocampal mossy fiber synapses. Conversely, phosphorylation of GluK2 at serine 868 in the absence of SUMOylation led to an increase in KAR surface expression by facilitating receptor recycling between endosomal compartments and the plasma membrane. Our results suggest a role for the dynamic control of synaptic SUMOylation in the regulation of KAR synaptic transmission and plasticity.