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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Involvement of N-type voltage dependent calcium channels in axon degeneration during experimental autoimmune optic neuritis / Uloga N-tipa voltazno zavisnih kalcijumskih kanala u degeneraciji aksona tokom eksperimentalnog autoimunog optickog neuritisa

Gadjanski, Ivana 31 October 2007 (has links)
No description available.
62

Resposta da pressão arterial durante exercício resistido em hipertensos:influência de anlodipina. / Blood pressure responses to dynamic resistance exercise: influence of amlodipine

Souza, Dinoelia Rosa de 09 November 2012 (has links)
O exercício resistido dinâmico é recomendado para hipertensos, mas a pressão arterial (PA) se eleva muito durante sua execução. Este estudo investigou o efeito do antagonista do canal de cálcio diidropiridínico, anlodipina, sobre a resposta da PA ao exercício resistido de diferentes intensidades. Onze hipertensos essenciais foram estudados após 4 semanas de uso de placebo e anlodipina, num desenho aleatório e duplo cego. Os voluntários realizaram o exercício de extensão de joelhos até a exaustão, seguindo os seguintes protocolos: a) 1 série em 100% de 1RM, b) 3 séries em 80% de 1RM; e c) 3 séries em 40% de 1RM. Antes e durante os exercícios, a PA foi medida diretamente na artéria radial. A anlodipina reduziu os valores absolutos da PA sistólica (225±6 vs 207±6 mmHg em 100%, 289±8 vs 273±10 mmHg em 80% e 289±10 vs 271±11 mmHg em 40%) e da PA diastólica (141± 3 vs 130±6 mmHg em 100%, 178±5 vs 169±6 mmHg em 80% e 176±8 vs 154±6 mmHg em 40%) em todas as intensidades. Ela também minimizou o aumento da PA diastólica que ocorreu na 2ª e 3ª séries do exercício realizado em 40% de 1 RM. Em conclusão, anlodipina é capaz de diminuir os valores máximos da PA atingidos durante a realização de exercícios resistidos de diferentes intensidades e minimizar o aumento progressivo da PA diastólica em exercícios mais prolongados.Estes efeitos podem reduzir o risco cardiovascular durante a execução de esforços resistidos em hipertensos / Dynamic resistance exercise is recommended for hypertensives. However, during its execution blood pressure (BP) presents a huge increase. This study investigated the effects of dyhidropyridine calcium channel antagonist, amlodipine, on BP responses during resistance exercises executed at different intensities. Eleven essential hypertensives were studied after 4 weeks of placebo and amlodipine administered at a random double blinded order. Volunteers were evaluated during the execution of the knee extension exercise performed with three different protocols: a) 1 set at 100% of 1RM (repetition maximum), b) 3 sets at 80% of 1RM, and c) 3 sets at 40% of 1RM. Before and during exercise, BP was directly measured at the radial artery. Amlodipine reduced the absolute values of systolic BP (225±6 vs 207±6 mmHg at 100%, 289±8 vs 273±10 mmHg at 80% e 289±10 vs 271±11 mmHg at 40%) and diastolic BP (141± 3 vs 130±6 mmHg at 100%, 178±5 vs 169±6 mmHg at 80% e 176±8 vs 154±6 mmHg at 40%) during all the exercise intensities. In addition, it mitigated diastolic BP increase that happened at the second and third sets of the exercise at 40% of 1 RM. In conclusion, amlodipine was able to decrease BP maximal values achieved during resistance exercise at different intensities, and minimizes diastolic BP increase in prolonged resistance exercises. These effects may confer some cardiovascular protection for hypertensives during the execution of resistance efforts
63

Planejamento e validação anti-proliferativa e anti-leishmania, de novos híbridos tri-funcionalizados unidos através do anel 1,2,3-triazol e compostos similares / Design, anti-proliferative and anti-leishmanial evaluation of new tri-functionalized hybrids linked through a 1,2,3-triazole moiety and similar compounds.

Federico, Leonardo Bruno 02 December 2016 (has links)
As concepções de moduladores da dinâmica dos microtúbulos, que levam ao bloqueio do ciclo celular, e de bloqueadores de canais de cálcio tipo L (Cav), tais como o 1,4-di-hidropiridinas e análogos, que diminuem a resistência do organismo humano aos tratamentos quimioterápicos através da inibição da proteína de transmembrana P-gp, são estratégias importantes tanto para terapias antitumorais quanto para leishmanicida. Esta abordagem tem mostrado resultados interessantes na diminuição da resistência à quimioterapia em câncer chamada de MDR (do inglês Multi Drug Resistence), além de também serem uma estratégia importante para controlar a fase inicial da leishmaniose. Diante desse contexto, e baseado no estudo de Ueki 2013 e colaboradores que, a partir de estudos anteriores, os quais relatam a superexpressão das enzimas estona deacetilase (HDAC) e catepsina L (CTSL) em células tumorais, propuseram um pró-fármaco seletivo, planejado a partir de um espaçador de lisina acetilada, que garante a liberação do fármaco seletivamente nas células tumorais, trabalhamos no desenvolvimento de uma nova proposta de pró-fármaco trifuncional. Nossa proposta foi desenvolvida a partir de estudos de triagem virtual, baseados em ligantes e em estrutura, predição das propriedades farmacocinéticas e toxicológicas (ADME/Tox) e também técnicas de bioinformática para a construção de um modelo de canal de cálcio, devido à inexistência de estruturas, do mesmo, que estivessem depositadas no banco de dados de proteínas PDB (Protein Data Bank). Paralelamente, nosso grupo de síntese colaborador sintetizou, através de técnicas de \"Click Chemistry\" e reações de Mitsunobu multicomponentes, uma biblioteca de novos híbridos trifuncionais, os quais, após estudos de atividade biológica, foram avaliados (in silico) frente à estrutura da tubulina, e os compostos mais promissores desta biblioteca serviram de base para novos estudos de triagem virtual. Para a obtenção dos nossos hits, executamos 4 estratégias de triagem virtual, separadas em 2 tarefas. Ao final, selecionarmos um total 59 hits, dos quais, 9 hits apresentam promissoras atividades bloqueadoras do canal de cálcio e 65 hits apresentam promissoras atividades moduladoras da tubulina. Estes hits seguem em estágio de compra e ensaios in vitro e após comprovada a eficácia dos mesmos, estes futuramente farão parte de uma nova proposta de pró-farmaco trifuncional. / The concepts of modulating microtubule dynamics, and calcium channel L-types (CAV) blockers are important strategies for anticancer and antileishmanial therapies. Microtubule modulators that blocks the cell cycle and the calcium channel blockers, such as, 1,4-dihydropyridines and analogues, reduce the resistance of the human body to chemotherapeutic treatments by inhibiting transmembrane P-gp protein. This approach has shown interesting results in reduced resistance to chemotherapy in cancer called MDR (Multi Drug Resistance), and an important strategy for controlling the early stage of leishmaniasis. In this context, we work to develop a new proposal for trifunctional prodrug. We have based on the study of Ueki 2013 and collaborators, which, from earlier studies with reported overexpression of both deacetylase estona enzymes (HDACs) and cathepsin L (CTSL) in tumor cells, proposed a selective prodrug. We considering an acetylated lysine link/spacer, which ensures the release of the drug selectively in tumor cells, have now designed this selective prodrug. Our proposal was developed from virtual screening studies, based on ligands and structure, prediction of pharmacokinetic and toxicological properties (ADME / Tox) and also bioinformatics techniques for the construction of a calcium channel model, due to the inexistence of Structures of the same that were deposited in the database of proteins PDB (Protein Data Bank). At the same time, our collaborating synthesis group synthesized, through Click Chemistry techniques and Mitsunobu multicomponent reactions, a library of new trifunctional hybrids, which, after studies of biological activity, were evaluated (in silico) against the structure of tubulin , And the most promising compounds from this library served as the basis for further virtual screening studies. To obtain our hits, we performed 4 virtual screening strategies, separated into 2 tasks. In the end, we selected 59 hits, of which 9 hits show promising calcium channel blocking activities and 65 hits show promising tubulin modulating activities. These hits follow in vitro purchase and testing, and after proven effectiveness, they will be part of a new tri prodrug proposal.
64

Efeito da tansulosina e do nifedipino na eliminação de fragmentos após litotripsia extracorpórea por ondas de choque em pacientes com cálculos renais: estudo prospectivo, duplo-cego e randomizado / Effect of tamsulosin and nifedipine on the clearance of fragments after extracorporeal shock waves lithotripsy in patients with kidney stones - a prospective, double-blind and randomized study

Vicentini, Fabio Carvalho 18 March 2011 (has links)
Introdução: A litotripsia extracorpórea por ondas de choque (LEOC) é o tratamento mais utilizado para cálculos renais de até 20 mm. O uso adjuvante de algumas drogas pode aumentar as taxas de sucesso do procedimento e diminuir a sua morbidade. Objetivos: Avaliar os efeitos da tansulosina e do nifedipino nas taxas de sucesso, nos episódios de dor e na velocidade de eliminação dos fragmentos após o tratamento de cálculos renais de 5 a 20 mm com uma única sessão de LEOC. Casuística e Métodos: Foram estudados prospectivamente 136 indivíduos portadores de cálculos renais entre 5 e 20 mm, submetidos à LEOC entre 2006 e 2009. Os pacientes foram divididos aleatoriamente em 3 grupos para receber diariamente tansulosina 0,4 mg, nifedipino retard 20mg ou placebo por até 30 dias da realização de LEOC. A analgesia foi feita com celecoxibe 200 mg. Os pacientes foram avaliados semanalmente por meio de radiografia de abdome. Foi definido como sucesso do tratamento a ausência de fragmentos maiores que 4 mm ao final de 30 dias. Os parâmetros avaliados foram: taxa de sucesso do tratamento, ocorrência de rua de cálculos, necessidade de analgésicos, intensidade de dor após a LEOC, tempo de eliminação de fragmentos, efeitos adversos da medicação e visitas ao Pronto Socorro. Resultados: Cento e onze pacientes completaram o estudo. Não houve diferenças demográficas entre os pacientes e nem em relação ao tamanho dos cálculos entre os grupos. As taxas de sucesso foram de 60,5% (23 de 38) no Grupo Tansulosina, 48,6% (17 de 35) no Grupo Nifedipino e 36,8% (14 de 38) no Grupo Placebo. (p=0,118) Entre os pacientes com cálculos de 10 a 20 mm, a taxa de sucesso foi significativamente maior nos Grupos Tansulosina (61,9%) e Nifedipino (60,0%) do que no Grupo Placebo (26,1%) (p=0,024), porém não foi significativa entre os cálculos de 5 a 9 mm (p=0,128). O Número Necessário para Tratar (NNT) da Tansulosina foi de 2,9 e o do Nifedipino foi de 3, considerando-se o uso para cálculos de 10 a 20 mm. Os pacientes que usaram nifedipino tiveram mais efeitos adversos do que os do Grupo Placebo (28,5 % x 2,6% respectivamente, p = 0,009), porém sem levar à interrupção do uso da drogas. Não houve diferença significativa entre os grupos Tansulosina x Nifedipino e Tansulosina x Placebo em relação aos efeitos adversos (p= 0,15 e p = 0,054, respectivamente). Não houve diferença entre os grupos com relação à intensidade da dor observada após o tratamento (p=0,28), ao número de comprimidos de Celecoxibe (p=0,39), ao tempo de eliminação dos fragmentos (p=0,6), à ocorrência de rua de cálculos (p=0,482) e ao número de vistas ao Pronto Socorro (p=0,175). Conclusões: O uso adjuvante de tansulosina ou de nifedipino após LEOC aumenta a taxa de sucesso para cálculos renais entre 10 e 20 mm, porém sem diminuir a intensidade da dor ou a necessidade de analgésicos após o tratamento, nem o tempo de eliminação dos fragmentos / Purpose: We evaluated the effects of the adjuvant use of tamsulosin and nifedipine after extracorporeal shock wave lithotripsy (SWL) for 5-20 mm kidney stones. Materials and Methods: We conducted a randomized double-blind trial involving 136 patients with radiopaque kidney stones between 2006 and 2009. Patients were divided into three groups to receive daily treatments of 0.4 mg tamsulosin, 20 mg nifedipine retard or placebo for up to 30 days after one session of SWL. The parameters assessed were success rate, analgesic requirements, pain intensity, time to clearance, adverse effects and occurrence of Steinstrasse. Results: The success rate was 60.5% (23 of 38) in the Tamsulosin group, 48.6% (17 of 35) in the Nifedipine group and 36.8% (14 of 38) in the Placebo group (p=0.118). For stones ranging from 10 to 20 mm, the success rates were significantly higher in the Tamsulosin (61.9%) and Nifedipine groups (60.0%) when compared with the Placebo group (26.1%) (p=0.024), but not for the 5-9 mm stones (p=0.128). The Number Needed to Treat was 2.9 for tamsulosin and 3 for nifedipine. Adverse events were more frequent in the Nifedipine than the Placebo Group (28.5% vs. 2.6%, respectively, p=0.009). There was no difference among groups with regard to stone and demographic characteristics, pain intensity, time to clearance and Steinstrasse. Conclusions: Adjuvant use of tamsulosin or nifedipine after SWL significantly increased the success rates for 10 to 20 mm renal stones and could be recommended. Both drugs had similar beneficial effects and adverse events
65

Caractérisation des signaux calciques générés par l'activation des deux voies synaptiques excitatrices des neurones de Purkinje / Characterization of calcium signals generated by activation of the two excitatory synaptic inputs in Purkinje neurons

Ait Ouares, Karima 11 April 2019 (has links)
Dans le cervelet, l’interaction entre l’activité des fibres parallèles (FPs) et celle de la fibre grimpante (FG), les deux principaux inputs excitateurs des neurones de Purkinje (NPs), engendre des signaux calciques supra-linéaires procurant des informations sur leur activité concomitante. Ce phénomène déclenche des mécanismes synaptiques qui induisent la dépression à court- ou à long-terme des synapses FP-NPs. L’activation des FPs génère des signaux calciques locaux confinés aux épines activées tandis que l’activation de la FG génère une dépolarisation qui se propage passivement dans les dendrites. Cette dépolarisation transitoire qui n’est pas locale joue un rôle important dans la régulation de la signalisation locale des FPs et leur plasticité. L’étude menée durant ma thèse s’est focalisée sur deux principaux points : les canaux dendritiques des NPs activés par la dépolarisation transitoire générée par l’activation de la FG et les mécanismes responsables de la génération des signaux dendritiques supra-linéaires associés à l’activité concomitante des FPs et de la FG. Les résultats reportés ici ont été obtenus en utilisant des méthodes optiques récemment développés.Nous avons caractérisé le comportement des canaux ioniques dendritiques qui sont activés par la dépolarisation dendritique générés par l’activation de la FG. Nous avons découvert que deux différents groupes de canaux ioniques sont sélectivement activés selon le potentiel membranaire initial. En effet, quand les dendrites sont hyperpolarisées, les CF-EPSPs activent principalement des canaux calciques voltage-dépendant (CCVDs) de type T, des canaux SK et des canaux potassiques voltage-dépendant (CPVDs) de type A. Ces derniers maintiennent le potentiel membranaire en dessous de ~0 mV. En revanche, quand les dendrites sont dépolarisées, les CCVDs de type T et les CPVDs de type A s’inactivent complètement et les CF-EPSPs activent des CCVDs de type P/Q, des CPVDs et des canaux BK. L’activation de cet ensemble de canaux déclenche des spikes calciques. Notamment, nous avons établi l’importance des CPVDs de type A dans le control du deuxième ensemble de canaux. En effet, ils limitent l’activation des CCVDs de type P/Q et les canaux potassiques associés empêchant le déclenchement des spikes calciques.Nous avons démontré que l’activation occurrente de la FG et des FPs induit deux différents types de signaux calciques supra-linéaires. L’induction de l’un ou de l’autre dépend du temps entre l’activation des deux inputs, qui est aussi un principal déterminant des mécanismes impliqués dans la génération des ces signaux calciques. Nous avons trouvé que quand les CF-EPSPs se produisent à de courts délais après la fin du burst des FPs, les signaux calciques supra-linéaires associés sont indépendant de l’activation des mGluR1 et sont générés par l’effet combiné de deux mécanismes : l’augmentation du flux calcique via les CCVD de type P/Q activés par la dépolarisation membranaire médiée par l’activation de FPs inactivant les CPVDs de type A; et la saturation transitoire des buffers calciques endogènes durant le burst des PF-EPSPs amplifiant les concentrations du Ca2+ libre. Quand les CF-EPSPs se produisent à de longs délais après la fin du burst des PF-EPSPs, les signaux calciques supra-linéaires associés dépendent de l’activation des mGluR1 et n’impliquent aucun des mécanismes précédents. Dans ce cas, nous avons démontré que les signaux calciques supra-linéaires sont corrélés avec l’augmentation du flux calcique via les conductances cationiques associées à l’activation des mGluR1.Les résultats reportés ici ont avancé notre compréhension sur la génération des signaux calciques supra-linéaires associés à l’activité concomitante des PFs et de la FGs ainsi les mécanismes qui y sont impliqués. Néanmoins, nous n’avons pas pu procurer une réponse définitive sur la nature du flux calcique médiant les signaux calciques supra-linéaires dépendant de l’activation des mGluR1s. / In the cerebellum, the interplay between PFs and CF inputs generates supralinear Ca2+ signals that provide the information on their concomitant occurrance. These phenomena trigger both short- and long-term depression at PF-PN synapses associated with motor learning and coordination, i.e. the primary functions of the cerebellum. While activation of PFs elicits local Ca2+ transients that are confined to activated spines, the activation of the CF generates a large depolarization that spreads passively into the dendrites. The CF-mediated transient dendritic depolarization, not localized, plays a fundamental role in dendritic integration and in regulating local PF signals and their plasticity at distal sites. The study carried out in my thesis addressed two crucial questions of this problem: the dendritic ion channels activated by the CF-mediated dendritic depolarization at different initial Vm and the mechanisms underlying dendritic supralinear Ca2+ signals associated with concomitant PF and CF activity. The results reported here were obtained using recent optical methods of Vm imaging and ultrafast Ca2+ imaging with low affinity Ca2+ and high affinity Ca2+ indicators combined with pharmacological analysis.During the first part of my work, I characterized the behavior of the dendritic Ca2+ and K+ channels activated by CF-EPSPs at different initial dendritic Vm, using optical measurements of Vm and Ca2+ transients. We found that two different sets of ion channels are selectively activated at different states. When the dendrite is hyperpolarized, CF-EPSPs mainly activate T-type voltage-gated Ca2+ channels (VGCCs), SK channels and A-type voltage-gated Ca2+ channels (VGKCs) that limit the transient Vm below ~0 mV. When in contrast the dendrite is depolarized, T-type VGCCs and A-type VGKCs are inactivated and CF-EPSPs activate P/Q-type VGCCs, high-voltage activated VGKCs and BK channels, initiating Ca2+ spikes. We demonstrated that A-type VGKCs play a crucial role in controlling the second set of channels. Indeed, these channels limit the activation of P/Q-type VGCCs and associated K+ channels, preventing Ca2+ spikes.During the second part of my work, we demonstrated that the concomitant activation of PF and CF triggers two different types of supralinear Ca2+ signals. The activation of one or the other path depends on the delay between the activation of the two inputs which is the crucial discriminator of the mechanisms involved in the generation of supralinear Ca2+ signals. We found that when CF-EPSPs occur near the end of a burst of PFs, the associated supralinear Ca2+ transients are independent of the activation of mGluR1 and are produced by a combined effect of two mechanisms: the increased Ca2+ influx through P/Q-type VGCCs enabled by PF-depolarization inactivating A-type VGKCs; and the transient saturation of endogenous Ca2+ buffers during the PF-EPSP burst amplifying free Ca2+ concentration. When CF-EPSPs occur at longer delays after the end of the PF burst, the associated supralinear Ca2+ transients are mGluR1-dependent and do not involve the mechanisms underlying the generation of mGluR1-independent supralinear Ca2+ transients. Instead, an entirely different mechanism is recruited. We found that, the supralinear Ca2+ transients were correlated with an increase in mGluR1-dependent Ca2+ influx via the slow mGluR1-activated cation conductance.The results reported here advance our understanding of the generation of supralinear Ca2+ transients associated with the concomitant PF and CF activity with respect to the potential molecular mechanisms that are involved. Nevertheless, we were not able to provide a definitive answer on the nature of the Ca2+ influx mediating mGluR1-depedent supralinear Ca2+ signals. This issue must be further explored in future experiments.
66

Mechanisms of Presynaptic CaV2.2 (N-type) Modulation

Chan, Allen 22 March 2010 (has links)
Neurotransmitter release at presynaptic terminals is a complex process involving calcium ion influx through voltage-gated calcium channels (CaV). In addition to their role as entry points through which calcium influx may occur, CaV are now understood to be fundamental components of a common release-site complex that is highly adapted for modulation. Consistent with this model, I investigated mechanisms of modulating a presynaptic calcium channel, CaV2.2, via a heterotrimeric G-protein pathway. Using the patch-clamp technique, I demonstrated in chick dorsal root ganglion (DRG) neurons that the slow kinetics of G-protein inhibition of CaV2.2 via GTPgammaS were limited by the rate of GDP dissociation from the G-protein nucleotide binding site. In addition, I investigated the role of G-protein regulation of CaV2.2 currents evoked by action potential-like stimuli. Here, I characterized an inhibited current that was advanced in time with respect to uninhibited controls. These currents exhibited a shorter latency to current activation and faster deactivation. These findings may have important physiological ramifications on signal transduction and timing. In addition to G-protein regulation, presynaptic CaV2.2 have been demonstrated to exhibit a resistance to voltage-dependent inactivation (VDI), a property thought to be important in determining channel availability and synaptic excitability. I demonstrated a role for dynamic palmitoylation in conferring resistance to VDI in presynaptic terminals of the chick ciliary ganglion. Using tunicamycin, an inhibitor of palmitoylation, I induced a hyperpolarizing shift in the steady-state-inactivation (SSI) profile of presynaptic CaV2.2. Finally, I examined the role of a CaV interacting protein, Munc18, as a potential regulator of CaV. I probed for alterations in CaV2.2 function in DRG neurons that had been transfected with Munc18 or Munc18 siRNA. Despite the intimate interaction between Munc18 and CaV2.2, no major effects on the fundamental characteristics of CaV2.2 function were observed. However, a hyperpolarizing shift in the inactivation profile of CaV2.2 was determined in DRG neurons in which Munc18 was knocked down. It is not clear if this was a direct consequence of Munc18 perturbation.
67

Mechanisms of Presynaptic CaV2.2 (N-type) Modulation

Chan, Allen 22 March 2010 (has links)
Neurotransmitter release at presynaptic terminals is a complex process involving calcium ion influx through voltage-gated calcium channels (CaV). In addition to their role as entry points through which calcium influx may occur, CaV are now understood to be fundamental components of a common release-site complex that is highly adapted for modulation. Consistent with this model, I investigated mechanisms of modulating a presynaptic calcium channel, CaV2.2, via a heterotrimeric G-protein pathway. Using the patch-clamp technique, I demonstrated in chick dorsal root ganglion (DRG) neurons that the slow kinetics of G-protein inhibition of CaV2.2 via GTPgammaS were limited by the rate of GDP dissociation from the G-protein nucleotide binding site. In addition, I investigated the role of G-protein regulation of CaV2.2 currents evoked by action potential-like stimuli. Here, I characterized an inhibited current that was advanced in time with respect to uninhibited controls. These currents exhibited a shorter latency to current activation and faster deactivation. These findings may have important physiological ramifications on signal transduction and timing. In addition to G-protein regulation, presynaptic CaV2.2 have been demonstrated to exhibit a resistance to voltage-dependent inactivation (VDI), a property thought to be important in determining channel availability and synaptic excitability. I demonstrated a role for dynamic palmitoylation in conferring resistance to VDI in presynaptic terminals of the chick ciliary ganglion. Using tunicamycin, an inhibitor of palmitoylation, I induced a hyperpolarizing shift in the steady-state-inactivation (SSI) profile of presynaptic CaV2.2. Finally, I examined the role of a CaV interacting protein, Munc18, as a potential regulator of CaV. I probed for alterations in CaV2.2 function in DRG neurons that had been transfected with Munc18 or Munc18 siRNA. Despite the intimate interaction between Munc18 and CaV2.2, no major effects on the fundamental characteristics of CaV2.2 function were observed. However, a hyperpolarizing shift in the inactivation profile of CaV2.2 was determined in DRG neurons in which Munc18 was knocked down. It is not clear if this was a direct consequence of Munc18 perturbation.
68

Molecular determinants of TRPV4 channel regulation

Garcia-Elias Heras, Anna 30 June 2011 (has links)
TRPV4 is a non-selective cation channel with a wide expression and multiple cellular and systemic functions. Described initially as an osmosensor, it can also be activated by temperature and cell swelling. Due to this variety of activating stimuli it may have a promiscuous gating behavior which is mostly unknown. This Thesis research aims to get in-depth in the understanding of the molecular determinants of TRPV4 regulation. I provide evidences that the inositol trisphosphate receptor and its modulatory function on TRPV4 relies on its binding to the C-terminal tail of TRPV4. I discuss the role of the channels’ N-terminal tail in osmotransduction and show how a mutation that results in a channel with an impaired response to osmotic environments is associated to a pathophysiological condition such as hyponatremia. I also highlight the importance of this N-terminal tail and the binding to the regulatory protein PACSIN3 for the global conformation of the channel. / El TRPV4 és un canal catiònic no selectiu d’expressió generalitzada i funcions diverses. Tot i que inicialment es va descriure com un osmosensor sistèmic, avui sabem que també es pot activar per temperatura o per augments del volum cel•lular. Degut a la diversitat d’estímuls, el canal presenta diferents vies d’activació la major part de les quals són desconegudes. Aquesta Tesi pretén estudiar en detall els mecanismes moleculars que regulen l’activitat del canal. Aportem evidències del lloc d’unió a la cua C-terminal del receptor d’inositol trifosfat així com la seva modulació sobre l’activitat del TRPV4. També discutim el rol de la cua N-terminal en la osmotransducció i presentem una mutació, generadora d’un canal amb una resposta anòmala a estímuls hipotònics, que està associada a una condició fisiopatològica com la hiponatremia. També destaquem la importància de la cua N-terminal i de la unió de la proteïna reguladora PACSIN3 en la conformació global del canal.
69

Planejamento e validação anti-proliferativa e anti-leishmania, de novos híbridos tri-funcionalizados unidos através do anel 1,2,3-triazol e compostos similares / Design, anti-proliferative and anti-leishmanial evaluation of new tri-functionalized hybrids linked through a 1,2,3-triazole moiety and similar compounds.

Leonardo Bruno Federico 02 December 2016 (has links)
As concepções de moduladores da dinâmica dos microtúbulos, que levam ao bloqueio do ciclo celular, e de bloqueadores de canais de cálcio tipo L (Cav), tais como o 1,4-di-hidropiridinas e análogos, que diminuem a resistência do organismo humano aos tratamentos quimioterápicos através da inibição da proteína de transmembrana P-gp, são estratégias importantes tanto para terapias antitumorais quanto para leishmanicida. Esta abordagem tem mostrado resultados interessantes na diminuição da resistência à quimioterapia em câncer chamada de MDR (do inglês Multi Drug Resistence), além de também serem uma estratégia importante para controlar a fase inicial da leishmaniose. Diante desse contexto, e baseado no estudo de Ueki 2013 e colaboradores que, a partir de estudos anteriores, os quais relatam a superexpressão das enzimas estona deacetilase (HDAC) e catepsina L (CTSL) em células tumorais, propuseram um pró-fármaco seletivo, planejado a partir de um espaçador de lisina acetilada, que garante a liberação do fármaco seletivamente nas células tumorais, trabalhamos no desenvolvimento de uma nova proposta de pró-fármaco trifuncional. Nossa proposta foi desenvolvida a partir de estudos de triagem virtual, baseados em ligantes e em estrutura, predição das propriedades farmacocinéticas e toxicológicas (ADME/Tox) e também técnicas de bioinformática para a construção de um modelo de canal de cálcio, devido à inexistência de estruturas, do mesmo, que estivessem depositadas no banco de dados de proteínas PDB (Protein Data Bank). Paralelamente, nosso grupo de síntese colaborador sintetizou, através de técnicas de \"Click Chemistry\" e reações de Mitsunobu multicomponentes, uma biblioteca de novos híbridos trifuncionais, os quais, após estudos de atividade biológica, foram avaliados (in silico) frente à estrutura da tubulina, e os compostos mais promissores desta biblioteca serviram de base para novos estudos de triagem virtual. Para a obtenção dos nossos hits, executamos 4 estratégias de triagem virtual, separadas em 2 tarefas. Ao final, selecionarmos um total 59 hits, dos quais, 9 hits apresentam promissoras atividades bloqueadoras do canal de cálcio e 65 hits apresentam promissoras atividades moduladoras da tubulina. Estes hits seguem em estágio de compra e ensaios in vitro e após comprovada a eficácia dos mesmos, estes futuramente farão parte de uma nova proposta de pró-farmaco trifuncional. / The concepts of modulating microtubule dynamics, and calcium channel L-types (CAV) blockers are important strategies for anticancer and antileishmanial therapies. Microtubule modulators that blocks the cell cycle and the calcium channel blockers, such as, 1,4-dihydropyridines and analogues, reduce the resistance of the human body to chemotherapeutic treatments by inhibiting transmembrane P-gp protein. This approach has shown interesting results in reduced resistance to chemotherapy in cancer called MDR (Multi Drug Resistance), and an important strategy for controlling the early stage of leishmaniasis. In this context, we work to develop a new proposal for trifunctional prodrug. We have based on the study of Ueki 2013 and collaborators, which, from earlier studies with reported overexpression of both deacetylase estona enzymes (HDACs) and cathepsin L (CTSL) in tumor cells, proposed a selective prodrug. We considering an acetylated lysine link/spacer, which ensures the release of the drug selectively in tumor cells, have now designed this selective prodrug. Our proposal was developed from virtual screening studies, based on ligands and structure, prediction of pharmacokinetic and toxicological properties (ADME / Tox) and also bioinformatics techniques for the construction of a calcium channel model, due to the inexistence of Structures of the same that were deposited in the database of proteins PDB (Protein Data Bank). At the same time, our collaborating synthesis group synthesized, through Click Chemistry techniques and Mitsunobu multicomponent reactions, a library of new trifunctional hybrids, which, after studies of biological activity, were evaluated (in silico) against the structure of tubulin , And the most promising compounds from this library served as the basis for further virtual screening studies. To obtain our hits, we performed 4 virtual screening strategies, separated into 2 tasks. In the end, we selected 59 hits, of which 9 hits show promising calcium channel blocking activities and 65 hits show promising tubulin modulating activities. These hits follow in vitro purchase and testing, and after proven effectiveness, they will be part of a new tri prodrug proposal.
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Efeito da tansulosina e do nifedipino na eliminação de fragmentos após litotripsia extracorpórea por ondas de choque em pacientes com cálculos renais: estudo prospectivo, duplo-cego e randomizado / Effect of tamsulosin and nifedipine on the clearance of fragments after extracorporeal shock waves lithotripsy in patients with kidney stones - a prospective, double-blind and randomized study

Fabio Carvalho Vicentini 18 March 2011 (has links)
Introdução: A litotripsia extracorpórea por ondas de choque (LEOC) é o tratamento mais utilizado para cálculos renais de até 20 mm. O uso adjuvante de algumas drogas pode aumentar as taxas de sucesso do procedimento e diminuir a sua morbidade. Objetivos: Avaliar os efeitos da tansulosina e do nifedipino nas taxas de sucesso, nos episódios de dor e na velocidade de eliminação dos fragmentos após o tratamento de cálculos renais de 5 a 20 mm com uma única sessão de LEOC. Casuística e Métodos: Foram estudados prospectivamente 136 indivíduos portadores de cálculos renais entre 5 e 20 mm, submetidos à LEOC entre 2006 e 2009. Os pacientes foram divididos aleatoriamente em 3 grupos para receber diariamente tansulosina 0,4 mg, nifedipino retard 20mg ou placebo por até 30 dias da realização de LEOC. A analgesia foi feita com celecoxibe 200 mg. Os pacientes foram avaliados semanalmente por meio de radiografia de abdome. Foi definido como sucesso do tratamento a ausência de fragmentos maiores que 4 mm ao final de 30 dias. Os parâmetros avaliados foram: taxa de sucesso do tratamento, ocorrência de rua de cálculos, necessidade de analgésicos, intensidade de dor após a LEOC, tempo de eliminação de fragmentos, efeitos adversos da medicação e visitas ao Pronto Socorro. Resultados: Cento e onze pacientes completaram o estudo. Não houve diferenças demográficas entre os pacientes e nem em relação ao tamanho dos cálculos entre os grupos. As taxas de sucesso foram de 60,5% (23 de 38) no Grupo Tansulosina, 48,6% (17 de 35) no Grupo Nifedipino e 36,8% (14 de 38) no Grupo Placebo. (p=0,118) Entre os pacientes com cálculos de 10 a 20 mm, a taxa de sucesso foi significativamente maior nos Grupos Tansulosina (61,9%) e Nifedipino (60,0%) do que no Grupo Placebo (26,1%) (p=0,024), porém não foi significativa entre os cálculos de 5 a 9 mm (p=0,128). O Número Necessário para Tratar (NNT) da Tansulosina foi de 2,9 e o do Nifedipino foi de 3, considerando-se o uso para cálculos de 10 a 20 mm. Os pacientes que usaram nifedipino tiveram mais efeitos adversos do que os do Grupo Placebo (28,5 % x 2,6% respectivamente, p = 0,009), porém sem levar à interrupção do uso da drogas. Não houve diferença significativa entre os grupos Tansulosina x Nifedipino e Tansulosina x Placebo em relação aos efeitos adversos (p= 0,15 e p = 0,054, respectivamente). Não houve diferença entre os grupos com relação à intensidade da dor observada após o tratamento (p=0,28), ao número de comprimidos de Celecoxibe (p=0,39), ao tempo de eliminação dos fragmentos (p=0,6), à ocorrência de rua de cálculos (p=0,482) e ao número de vistas ao Pronto Socorro (p=0,175). Conclusões: O uso adjuvante de tansulosina ou de nifedipino após LEOC aumenta a taxa de sucesso para cálculos renais entre 10 e 20 mm, porém sem diminuir a intensidade da dor ou a necessidade de analgésicos após o tratamento, nem o tempo de eliminação dos fragmentos / Purpose: We evaluated the effects of the adjuvant use of tamsulosin and nifedipine after extracorporeal shock wave lithotripsy (SWL) for 5-20 mm kidney stones. Materials and Methods: We conducted a randomized double-blind trial involving 136 patients with radiopaque kidney stones between 2006 and 2009. Patients were divided into three groups to receive daily treatments of 0.4 mg tamsulosin, 20 mg nifedipine retard or placebo for up to 30 days after one session of SWL. The parameters assessed were success rate, analgesic requirements, pain intensity, time to clearance, adverse effects and occurrence of Steinstrasse. Results: The success rate was 60.5% (23 of 38) in the Tamsulosin group, 48.6% (17 of 35) in the Nifedipine group and 36.8% (14 of 38) in the Placebo group (p=0.118). For stones ranging from 10 to 20 mm, the success rates were significantly higher in the Tamsulosin (61.9%) and Nifedipine groups (60.0%) when compared with the Placebo group (26.1%) (p=0.024), but not for the 5-9 mm stones (p=0.128). The Number Needed to Treat was 2.9 for tamsulosin and 3 for nifedipine. Adverse events were more frequent in the Nifedipine than the Placebo Group (28.5% vs. 2.6%, respectively, p=0.009). There was no difference among groups with regard to stone and demographic characteristics, pain intensity, time to clearance and Steinstrasse. Conclusions: Adjuvant use of tamsulosin or nifedipine after SWL significantly increased the success rates for 10 to 20 mm renal stones and could be recommended. Both drugs had similar beneficial effects and adverse events

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