FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A lesÃo de reperfusÃo (LR) ocorre em diversos orgÃos e tecidos durante o restabelecimento do fluxo sangÃÃneo apÃs episÃdios de isquemia prolongada. Em diversas Ãreas clÃnicas esta lesÃo à temida pelas complicaÃÃes decorrentes da demora no restabelecimento do fluxo vascular. Nos transplantes de ÃrgÃos, nos retalhos microcirÃrgicos e nas cirurgias de revascularizaÃÃo miocÃrdica, a LR, dependendo de sua intensidade, pode prejudicar o benefÃcio destes procedimentos. Dentre as estratÃgias propostas para atenuar a LR, o prÃ-condicionamento isquÃmico (PCI) consiste na induÃÃo de pequenos perÃodos de isquemia seguidos de reperfusÃo, realizados antes da isquemia prolongada. Este estudo foi avaliar o efeito do PCI da pata posterior na sobrevida de retalhos cutÃneos randomizados em dorso (RCRD) e o efeito antiinflamatÃrio local e sistÃmico deste fenÃmeno. Para tanto o PCI foi induzido atravÃs da isquemia da pata posterior de ratos Wistar por 10 minutos seguida de 30 minutos de reperfusÃo. Diferentes grupos de ratos foram submetidos à confecÃÃo de RCRD, à induÃÃo de edema de pata (EP), ipsilateral (IPS) e contralateral (CON), por carragenina (Cg) ou dextran (Dx), cistite hemorrÃgica (CH) por ifosfamida (IFO) ou lesÃo gÃstrica (LG) por indometacina (INDO). Os grupos controles (C) receberam o mesmo tratamento, porÃm sem PCI. A Ãrea de sobrevida (AS) do RCRD foi calculada pela superfÃcie de tecido viÃvel (cm2), o EP atravÃs da variaÃÃo do volume das patas (ml), o edema vesical (EV) pelo peso Ãmido da bexiga (mg), o aumento da permeabilidade vascular (APV) pelo extravasamento de azul de Evans (&#61549;g), o Ãndice de lesÃo gÃstrica (ILG) pela soma das extensÃes das lesÃes encontradas na mucosa (mm), e a infiltraÃÃo neutrofÃlica (IN) pela atividade da mieloperoxidade (MPO) (U/mg). O PCI foi capaz de aumentar a AS do RCRD (C=4,16Â0,29 e PCI=6,42Â0,14, p<0,01). O EP e o APV induzidos por Cg (100&#61549;g, sc) ou Dx (200&#61549;g, sc), tanto na pata IPS quanto CON, foram reduzidos pelo PCI (EP IPS Cg â C=0,63+0,05 e PCI=0,26+0,02; APV IPS Cg â C=10,03+0,68 e PCI=5,82+1,18; EP IPS Dx â C=1,08+0,11 e PCI=0,54+0,06; APV IPS Dx â C= 24,38+3,02 e PCI=13,51+1,70; EP CON Cg â C=0,63+0,10 e PCI=0,30+0,05; APV CON Cg â C=16,16+2,18 e PCI=9,19+1,12; EP CON Dx â C=0,95+0,10 e PCI=0,49+0,10; APV CON Dx â C=24,09+2,97 e PCI=13,15+1,62; p<0,01). O PCI inibiu o EV e o APV da CH induzida por IFO (200mg/kg, ip) (EV â C=206,6+10,95 e PCI=126+5,66; APV â C=38,55+2,19 e PCI=17,74+2,18; p<0,001). Tanto a LG quanto a IN induzidas por INDO (20mg/kg, vo) foram bloqueadas pelo PCI (ILG â C=20,54+2,05 e PCI=2,00+0,93; IN â C=9,67+2,05 e PCI=3,49+0,83; p<0,001). Os resultados indicam que o PCI aumenta a sobrevida de RCRD e apresenta um efeito antiinflamatÃrio local e sistÃmico em modelos de inflamaÃÃo aguda. O esclarecimento do mecanismo atravÃs do qual o PCI atenua a lesÃo inflamatÃria poderà trazer importantes contribuiÃÃes em situaÃÃes clÃnicas onde esta lesÃo constitui um fator complicador, podendo propiciar o desenvolvimento de novas abordagens profilÃticas e/ou terapÃuticas. / The reperfusion injury (RI) occurs when there is delay in restoring blood flow to organs and tissues. Among the strategies proposed to attenuate the RI is the ischemic preconditioning (IPC), which consists of induction of brief ischemic periods followed by reperfusion performed before the sustained ischemic insult. In the first part, this study aimed to evaluate the role of nitric oxide (NO), cyclic guanosine monophosphate (cGMP) and ATP-sensitive potassium channels (K+ATP) in the inhibitory effect of hind limb IPC on the mice peritoneal cavity neutrophil migration (NM). In the second part, the objective was to evaluate the potential systemic antinociceptive effect of IPC in mechanical plantar hypernociception test (MPH; Von Frey) in rats and to evaluate the involvement of NO, cGMP and K+ATP channels in this event. In the first part, the IPC was induced by hind limb ischemia for 10 min followed by 30 min of reperfusion in wild and knockout mice to inducible NO synthase (iNOS -/-). The leukocyte rolling (LR), leukocyte adhesion (LA) and NM were induced by ip administration of Carrageenan (Cg, 500 &#61549;g/cavity) and results expressed in number of leukocytes/min, number of adherent leukocytes/100 &#61549;m2 cells and number of neutrophils x 106/cavity, respectively. Different groups of animals were treated with saline (SAL), Aminoguanidine (AG, sc, 100mg/kg), ODQ (ip, 8 &#61549;mol/kg) or Glibenclamide (GBC, sc, 20 mg/kg) 30 min before IPC induction. Controls received the same treatment, but without IPC. In the second part, the IPC was induced by hind limb ischemia for 10 min followed by 30 min of reperfusion in male Wistar rats (180-200g). Cg (300 &#61549;g, intraplantar) or Prostaglandin E2 (PGE2 - 400 ng, intraplantar) were used as hypernociceptive stimulus on left paw immediately after induction of IPC in contralateral paw. Different groups of animals were treated 30 min before induction of IPC with AG (100 &#61549;g/kg, intraplantar), LNMMA (50 &#61549;g, intraplantar), ODQ (8 &#61549;g, intraplantar) or GBC (160 &#61549;g, intraplantar). Controls received the same treatments, but without IPC. The quantification of MPH was performed through subtraction strength/pressure (g) required to cause withdrawal of paw in contact with an apparatus of eletronic von Frey mensuread before hypernociceptive stimulus, by measure obtained 3h after administration of Cg or PGE2. The LR, LA and NM induced by Cg in the peritoneal cavity were significantly (p <0,01) inhibited by hind limb IPC of wild animals (LR= 75.94%, LA= 56.51%, NM= 79.01 %), but these effects were not observed in animals iNOS -/-. The treatment of wild animals with AG and ODQ, but not with GBC, abrogated the inhibitory effect of IPC on NM induced by Cg. Treatment of animals with AG, GBC or ODQ did not significantly alter the NM induced by Cg in the peritoneal cavity. We also observed that IPC did not alter the TNF-&#61537;, IL1-&#61538; and CXCL1 chemokine levels induced by Cg in the peritoneal cavity. The mechanical hypernociception induced by Cg or PGE2 in left hind paw was significantly reduced (p <0,01) when IPC was performed in the right paw (55% and 68%). The treatment of animals with AG, LNMMA, ODQ or GBC, before IPC, abrogated the antinociceptive effect of IPC. Treatment of animals with AG, LNMMA, ODQ or GBC did not significantly alter the hypernociception induced by noxious stimulation. Our results show that IPC has an inhibitory effect on remote NM, with NO an important mediator involved in this process, probably through the cGMP pathway. This inhibitory effect of IPC does not depend on the opening of K+ATP channels, or inhibition of synthesis and/or release of pro-inflammatory cytokines. The elucidation of the mechanism by which IPC inhibits the NM may make important contributions to clinical situations where neutrophil infiltration is a complicating factor. The IPC also has a potent inhibitory effect on inflammatory pain, with NO seems to be one important mediator involved in this protective effect of IPC, acting through the cGMP/K+ATP channel pathway. This is the first demonstration described in the literature of systemic antinociceptive effect of IPC, and the elucidation of the mechanisms involved in this process is fundamental for pain management induced by several inflammatory stimuli.

Made available in DSpace on 2017-07-10T17:37:55Z (GMT). No. of bitstreams: 1 2012_Fabiane_Cristina_Gusatto.pdf: 1185360 bytes, checksum: f382da60fcc8954539e4a24af95a8857 (MD5) Previous issue date: 2012-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Jatropha curcas is a shrub with high potential for biodiesel production, formation of roads, fences, trees, grown in semi-arid, and can measure two to three meters in height and 20 centimeters. The preconditioning of seeds is to control the imbibitions of aqueous solutions, until there is osmotic equilibrium, increasing the speed and percentage of germination and seedling emergence, not interfering in the seed so toxic. Thus, this study aims to evaluate the effect of preconditioning in the speed of germination and emergence of seeds of Jatropha curcas L. stored. We used seeds will not benefit of Jatropha curcas from Dourados (MS), for the first test and for the following they were dried in the sun and shade. We analyzed the water content, mass and size of one thousand seeds. The seeds were placed in a glass container and stored in cold chamber at 13ºC for different periods: 0,90, 180, 270, and 360 days. After each storage period, seeds were preconditioned with polyethylene glycol 6000 at 35ºC with concentrations of -0.2 MPa, 0.6 MPa, MPa -1.0, -1.4 MPa and the witness 0 MPa. Germination tests were performed on sand and evaluated the rate of emergence speed and percentage of germination. Sun-drying is best, generates higher rates of germination, with preconditioning temperature of 35ºC, the potentials of -1,4 MPa, in the sun and shade -1,0 MPa for 180 days of storage in glass chamber / O pinhão-manso (Jatropha curcas L.) é um arbusto oleaginoso com alto potencial de produção de biodiesel, formação de cercas-vias, arborização, cultivado no semi-árido, podendo medir de dois a três metros de altura e 20 centímetros de diâmetro no caule. O osmocondicionamento de sementes consiste em controlar a embebição de soluções aquosas, até que haja o equilíbrio osmótico, aumentando a velocidade e porcentagem de germinação e emergência das plântulas, não interferindo na semente de forma tóxica. Desta forma, o presente trabalho tem por objetivo avaliar o efeito do osmocondicionamento na velocidade de germinação e emergência das sementes de pinhão-manso armazenadas. Utilizou-se sementes de pinhão-manso provenientes de Dourados (MS), com frutos secos ao sol e à sombra. Foram analisados o teor de água, massa de mil sementes e tamanho de mil sementes. As sementes foram acondicionadas em recipiente de vidro e armazenadas em câmara fria a 13oC por diferentes períodos: 0,90, 180, 270, e 360 dias. Após cada período de armazenamento, as sementes foram osmocondicionadas com polietileno glicol 6000 à temperatura de 35ºC com as concentrações de -0,2MPa, -0,6MPa, -1,0MPa, -1,4MPa e a testemunha 0MPa. Os testes de germinação foram realizados em areia e avaliou-se o índice de velocidade de emergência e a porcentagem de germinação. A secagem ao sol é a mais indicada, gera maiores índices de porcentagem de germinação, o potencial osmótico que gerou os melhores resultados para a porcentagem de germinação com frutos secos ao sol foi -1,4 MPa e à sombra foi -1,0 MPa por 180 dias de armazenamento em vidro em câmara fria

Previous studies indicate that the degree of UV-Binduced photosynthetic inhibition may be highly dependent upon the photosynthetic photon flux density (PPFD, total quantum flux in the waveband 400-700 nm) incident on a plant. This study illustrates that Essex soybean leaves (Glycine max) preconditioned under high PPFD suffered less UV-B-induced photoinhibition than when preconditioned under low PPFD. However, sensitivity to UV-B increased when soybean leaves received high-PPFD as a concomitant treatment. The relative msgnitude of UV-B-induced damage was similar for both light-limited and light-saturated photosynthesis. This probably indicates that UV-B is inhibiting fundamentally different photosynthetic processes. Soybean leaves preconditioned under high PPFD had greater specific-leaf-weight, chlorophyll a/b ratio, and crude flavonoid content. The total chlorophyll concentration of soybean leaves preconditioned under high PPFD increased slightly over a UV-B irradiation period of five hours. Total chlorophyll concentration of leaves preconditioned under low PPFD decreased slightly in response to the same irradiation period.

PKCe plays a very important role in mediating the protection against myocardial ischemia and reperfusion injury induced by ischemic preconditioning (IPC) and pharmacologic preconditioning (PPC). The redistribution of PKCe was assessed by subcellular fractionation and western blotting in the Langendorff-perfused rabbit heart. Either 5min ischemia or 5min administration of adenosine A1 and/or A3 agonists, bradykinin, angiotensin II, and d1-opioid agonists resulted in PKCe redistribution from the cytosol to the mitochondria. This effect of IPC on PKCe redistribution was visible up to at least 30min of reperfusion, while that of PPC was lost by 10min of drug washout, indicative of the transient nature of PKCe redistribution. PKCe redistribution to mitochondria by IPC was also visualized using immunogold electron microscopy. Thus, IPC and PPC caused PKCe redistribution from the cytosol to the mitochondria, which was longer-lasting in IPC than in PPC.

PKCe plays a very important role in mediating the protection against myocardial ischemia and reperfusion injury induced by ischemic preconditioning (IPC) and pharmacologic preconditioning (PPC). The redistribution of PKCe was assessed by subcellular fractionation and western blotting in the Langendorff-perfused rabbit heart. Either 5min ischemia or 5min administration of adenosine A1 and/or A3 agonists, bradykinin, angiotensin II, and d1-opioid agonists resulted in PKCe redistribution from the cytosol to the mitochondria. This effect of IPC on PKCe redistribution was visible up to at least 30min of reperfusion, while that of PPC was lost by 10min of drug washout, indicative of the transient nature of PKCe redistribution. PKCe redistribution to mitochondria by IPC was also visualized using immunogold electron microscopy. Thus, IPC and PPC caused PKCe redistribution from the cytosol to the mitochondria, which was longer-lasting in IPC than in PPC.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

La résolution de l'équation des ondes acoustiques et élastiques en 3D dans le domaine fréquentiel représente un enjeu majeur dans le cadre de l'inversion des formes d'ondes pour l'imagerie haute résolution de cibles crustales (Virieux, 2009). Après discrétisation, ce problème revient à résoudre un système linéaire à valeurs complexes, creux, de grande taille non défini et mal conditionné. Les méthodes d'inversion sismique requièrent la solution de ce problème pour l'évaluation du problème direct pour un grand nombre de sources (plusieurs milliers voir dizaines de milliers). Dans l'approximation acoustique, les méthodes directes sont privilégiées. Cependant, le coût mémoire de ces méthodes les rendent aujourd'hui inutilisables pour résoudre les problèmes élastiques 3D. En raison de leur plus faible coût mémoire, les méthodes itératives pour les équations en fréquence peuvent être considérées pour l'élastodynamique. Cependant, une convergence rapide passe par des préconditionneurs adaptés pour les solveurs itératifs. Par ailleurs, les stratégies pour résoudre des systèmes linéaires avec des seconds membres multiples ne sont pas aussi efficaces que pour les méthodes directes. La modélisation dans le domaine temporelle quant à elle présente une importante complexité en coût de calcul et cette complexité croît linéairement avec le nombre de sources.Dans cette thèse, l'approche utilisant un solveur itératif est considérée. Le solveur itératif CARP-CG introduit par Gordon (2010) est considéré. Cette méthode est basée sur la méthode de Kaczmarz qui transforme un système linéaire mal conditionné en un système hermitien, positif et qui peut être résolu en utilisant les méthodes du type gradient conjugué (CG). Dans des configurations de forts contrastes et hétérogénéités, ce solveur s'est révélé être extrêmement robuste alors que les méthodes itératives standards basées sur les sous-espaces de Krylov telles que GMRES et BiCGSTAB nécessitent l'utilisation d'un préconditionneur pour converger (Li, 2015). Malgré les bonnes propriétés de la méthode CARP-CG, le nombre d'itérations nécessaires pour atteindre une précision suffisante reste néanmoins élevé. Je présente alors une stratégie de préconditionnement adaptée au problème de propagation des ondes et à la méthode CARP-CG. Ce préconditionneur est un inverse creux et approché d'un opérateur de propagation des ondes fortement amorti. Le calcul du préconditionneur est réalisé grâce un algorithme massivement parallèle pour les architectures à mémoire distribuée.La méthode développée est appliquée à des cas d'étude réalistes. Les applications sont faites sur des modèles synthétiques 2D dans l'approximation visco-acoustique pour des fréquences allant jusqu'à 40 Hz puis dans l'approximation élastique pour des fréquences allant jusqu'à 20 Hz. Ces études montrent l'efficacité de la méthode CARP-CG munie de la stratégie de préconditionnement. Le nombre d'itérations est fortement réduit (jusqu'à un facteur 9) permettant d'améliorer considérablement la complexité de la méthode CARP-CG. Des gains en temps de calcul allant jusqu'à un facteur 3.5 sont ainsi obtenus. La méthode est ensuite appliquée à un cas 3D synthétique et réaliste dans l'approximation visco-élastique pour des fréquences allant de 1.25 Hz à 7.5 Hz. Des résultats encourageants sont obtenus. Munie du préconditioneur, la méthode CARP-CG permet de résoudre ces systèmes linéaires deux fois plus rapidement.La stratégie de préconditionnement implique la nécessité de plus grandes ressources en mémoire pour le solveur itératif; cependant, elles ne constituent pas une limitation pour la méthode et restent très négligeables devant celles requises par les solveurs directs. La principale limitation réside dans le temps de calcul qui demeure assez significatif. Cependant, cette méthode constitue un solveur compétitif comparé aux autres solveurs en temps et direct utilisés aujourd'hui dans le cadre de l'inversion des formes d'ondes. / A robust and efficient wave modeling method is the cornerstone of high resolution seismic inversion methods such as the frequency-domain Full Waveform Inversion (Virieux, 2009). After discretization, frequency-domain wave modeling amounts to the solution of large (up to several billion of unknowns for realistic case studies), sparse, indefinite and ill-conditioned linear systems. Furthermore, seismic inversion methods require the solution of this problem for numerous sources (from several thousands up to tens of thousands). In the acoustic approximation, 3D real case studies can be handled efficiently using direct solvers. However because of their tremendous intrinsic memory requirements, they are not yet adapted to the solution of the 3D elastodynamics equations. Iterative solvers provide an alternative to direct solvers. However, they require a preconditioning strategy to ensure convergence for the frequency-domain wave equation. Besides, multiple right-hand sides linear systems are not treated as efficiently as direct solvers do.In this thesis, we are interested in the use of a robust iterative solver adapted to the solution of these systems called CARP-CG (Gordon, 2010). The CARP-CG method has shown robust convergence properties for 2D and 3D elastic problems in highly heterogeneous media compared to standard Krylov methods such as GMRES or Bi-CGSTAB which require the use of a preconditioner to ensure convergence (Li, 2015). Despite the good convergence properties of CARP-CG, the latter still requires a large number of iterations to reach sufficient accuracy. I introduce an efficient preconditioning strategy adapted to the CARP-CG method and the frequency-domain wave problem. This preconditioner is computed as a sparse approximate inverse of a strongly damped wave propagation operator. The computation of the preconditioner is performed in a massively parallel algorithm for distributed memory architectures.The efficiency of the preconditioner is evaluated on several case studies. First, applications are performed on realistic synthetic models in the 2D visco-acoustic approximation (up to $40$ Hz) and the 2D visco-elastic approximation (up to $20$ Hz). These studies show that the CARP-CG method together with the preconditioning strategy is robust and efficient. The number of iterations is significantly reduced (up to a factor $9$) enabling a speedup in the computation time by a factor up to $3.5$. Second, this method is investigated in the 3D elastic approximation on a realistic synthetic case study on the range of frequencies 1.25 to 7.5 Hz. Very encouraging results are obtained with a significant reduction in the number of iterations. A slow increase of the number of iterations with respect to the frequency is noted.This preconditioning strategy adapted to the CARP-CG method implies larger memory requirements. However, this extra memory cost remains one order lower compared to direct solver memory requirement, and should be affordable on standard HPC facilities. The main bottleneck preventing from the possible use of this iterative solver for 3D elastic FWI remains the computation time for the wave equation solves.

Introdução: A hipotermia tópica e o pré-condicionamento isquêmico local isoladamente reduzem a lesão renal por isquemia-reperfusão (I/R). Possivelmente, a associação de ambas estratégias tem efeitos protetores sinergísticos. Objetivos: Estudar os efeitos do pré-condicionamento local associado a hipotermia tópica na lesão renal por I/R, principalmente quanto às alterações histológicas, dano por estresse oxidativo, atividade antioxidante tecidual e parâmetros bioquímicos funcionais. Métodos: Quarenta ratos Wistar foram aleatoriamente alocados para cinco protocolos experimentais realizados no rim esquerdo: hipotermia tópica por 40 min sem isquemia (HT), isquemia quente por 40 min (IR), pré-condicionamento isquêmico (15 min de isquemia + 10 min de reperfusão) seguido de isquemia quente por 40 min (PCI+IR), isquemia fria por 40 min (HT+IR) e pré-condicionamento isquêmico seguido de isquemia fria por 40 min (PCI+HT+IR). Nefrectomia direita foi realizada em todos os ratos antes de qualquer procedimento. Oito rins direitos aleatoriamente designados constituíram o grupo controle Após 240 min de reperfusão, o rim esquerdo foi retirado para avaliar as alterações histológicas, a peroxidação lipídica (níveis de F2-isoprostanos [F2IP]) e a atividade enzimática antioxidante (catalase [CAT] e superóxido dismutase [SOD]). A função renal foi avaliada através da creatinina e uréia séricas. Resultados: O grupo PCI+HT+IR não foi diferente dos outros grupos submetidos a isquemia quanto às alterações histológicas, peroxidação lipídica e atividade enzimática antioxidante. A creatinina no grupo PCI+HT+IR foi mais baixa comparado ao grupo PCI+IR, mas semelhante ao grupo HT+IR. Conclusões: A combinação de pré-condicionamento local e hipotermia tópica não resultou em proteção à lesão por I/R. Além disso, o PCI local isolado seguido de isquemia quente prejudicou a função renal mais que a isquemia quente isolada. / Purpose: Topical hypothermia and local ischemic preconditioning have been shown to reduce renal ischemia-reperfusion (I/R) injury individually. We examined whether combination of both strategies lessens renal I/R injury. Methods: Post right nephrectomy, 40 male Wistar rats were randomly assigned to five experimental protocols performed in the left kidney: topical hypothermia without ischemia (TH), warm ischemia (IR), ischemic preconditioning followed by warm ischemia (IPC+IR), cold ischemia (TH+IR), and ischemic preconditioning followed by cold ischemia (IPC+TH+IR). Eight randomly assigned right kidneys constituted the control group. After 240 min of reperfusion, the left kidney was retrieved to evaluate histological changes, lipid peroxidation and antioxidant enzymes activity. Serum was collected to evaluate urea and creatinine. Results: IPC+TH+IR group revealed no difference to any other group subjected to ischemia in relation to histological changes, lipid peroxidation and antioxidant enzymes activity. Creatinine was lower in IPC+TH+IR group compared with IPC+IR, but showed no difference compared to TH+IR group. Conclusions: Combination of local ischemic preconditioning (IPC) and topical hypothermia conferred no protection in renal I/R injury. Moreover, local IPC solely followed by warm ischemia impaired renal function more than warm ischemia alone.

Submitted by VINÍCIUS MONTEIRO ARANTES null (viniciusma43@yahoo.com.br) on 2016-04-07T17:19:19Z No. of bitstreams: 1 Vinicius Monteiro Arantes (Doutorado) - Pós defesa.pdf: 1192517 bytes, checksum: 45c5c5f675af52789c6d2d6a395b44b0 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-04-08T11:47:33Z (GMT) No. of bitstreams: 1 arantes_vm_dr_bot.pdf: 1192517 bytes, checksum: 45c5c5f675af52789c6d2d6a395b44b0 (MD5) / Made available in DSpace on 2016-04-08T11:47:33Z (GMT). No. of bitstreams: 1 arantes_vm_dr_bot.pdf: 1192517 bytes, checksum: 45c5c5f675af52789c6d2d6a395b44b0 (MD5) Previous issue date: 2016-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Introdução: a lesão por isquemia-reperfusão (LIR) é uma importante causa de lesão renal aguda experimentada na prática clínica. A restauração da perfusão aos tecidos após um período de isquemia inicia uma cascata de inflamação associada ao acúmulo de íons, formação de espécies reativas de oxigênio (ERO), disfunção endotelial e ativação imune. O condicionamento isquêmico é a aplicação de breves ciclos de interrupção seguidas de restauração do fluxo sanguíneo, tendo o objetivo de adaptar os tecidos à isquemia. Pode ser aplicado antes do estímulo principal, como précondicionamento (PCI), ou depois, sendo denominado pós-condicionamento (PCoI). Metodologia: estudo experimental realizado com 40 ratos wistar, divididos em cinco grupos para análise comparativa: Sham (S): laparotomia; Controle (C): laparotomia e 30 min de isquemia; Pré-condicionamento (PRE): laparotomia, PCI e 30 min de isquemia; Pré e Pós-condicionamento (PRE/POS): laparotomia, PCI, 30 min de isquemia e PCoI; Pós-condicionamento (POS): laparotomia, 30 min de isquemia e PCoI. A comparação entre os grupos foi realizada pela análise bioquímica sérica de creatinina, ureia, lipocalina associada à gelatinase de neutrófilos (NGAL) e histolologia. Resultados: apenas o grupo Sham apresentou valores estatisticamente menores dos marcadores de lesão renal e menor incidência de lesão tubular renal à histologia (S<C=PRÉ=PRÉ/PÓS=PÓS). Discussão e conclusão: no presente estudo, o PCI e o PoCI, isoladamente ou em conjunto, foram incapazes de prevenir dano estrutural tubular renal. A duração do período isquêmico é um aspecto crítico nas estratégias de condicionamento. Os resultados encontrados indicam que o condicionamento pode não melhorar os desfechos, e em alguns casos pode ser prejudicial. / Background: Ischemia-reperfusion injury (IRI) is an unavoidable aspect of transplantation, as well as an important cause of acute kidney injury in clinical practice. Restoration of the blood supply after an ischemic period activates an inflammatory cascade associated with multiple processes, including ion accumulation, free reactive oxygen species (ROS) formation, endothelial dysfunction, and immune activation. Ischemic “conditioning” refers to the application of a brief series of ischemic periods followed by reperfusion in the setting of major ischemia. In ischemic preconditioning (IPC), the conditioning stimulus is applied before the major ischemic event, whereas in ischemic postconditioning (IPoC), it is applied after the event. Methods: Forty Wistar rats were randomized into five groups: Sham (S): laparotomy; Control (C): laparotomy and 30 min ischemia; Preconditioning (PRE): laparotomy, IPC, and 30 min ischemia; Preconditioning and Postconditioning (PRE/POST): laparotomy, IPC, 30 min ischemia, and IPoC; Postconditioning (POST): laparotomy, 30 min ischemia, and IPoC. Serum analyses of creatinine and neutrophil gelatinaseassociated lipocalin (NGAL) were performed, and renal histology was also examined. Results: Severe tubular injury and increases in creatinine were observed in all groups except the S group, and no significant differences were detected between the other groups (S<C=PRE=PRE/POST=POST). Conclusions: IPC and IPoC, together or separately, were unable to exert a protective effect against tubular cell injury and preserve kidney function. The duration of the ischemic period is a critical aspect of the conditioning strategy. Our results indicate that conditioning may not improve the outcome, and it may even be harmful.

Introdução: A hipotermia tópica e o pré-condicionamento isquêmico local isoladamente reduzem a lesão renal por isquemia-reperfusão (I/R). Possivelmente, a associação de ambas estratégias tem efeitos protetores sinergísticos. Objetivos: Estudar os efeitos do pré-condicionamento local associado a hipotermia tópica na lesão renal por I/R, principalmente quanto às alterações histológicas, dano por estresse oxidativo, atividade antioxidante tecidual e parâmetros bioquímicos funcionais. Métodos: Quarenta ratos Wistar foram aleatoriamente alocados para cinco protocolos experimentais realizados no rim esquerdo: hipotermia tópica por 40 min sem isquemia (HT), isquemia quente por 40 min (IR), pré-condicionamento isquêmico (15 min de isquemia + 10 min de reperfusão) seguido de isquemia quente por 40 min (PCI+IR), isquemia fria por 40 min (HT+IR) e pré-condicionamento isquêmico seguido de isquemia fria por 40 min (PCI+HT+IR). Nefrectomia direita foi realizada em todos os ratos antes de qualquer procedimento. Oito rins direitos aleatoriamente designados constituíram o grupo controle Após 240 min de reperfusão, o rim esquerdo foi retirado para avaliar as alterações histológicas, a peroxidação lipídica (níveis de F2-isoprostanos [F2IP]) e a atividade enzimática antioxidante (catalase [CAT] e superóxido dismutase [SOD]). A função renal foi avaliada através da creatinina e uréia séricas. Resultados: O grupo PCI+HT+IR não foi diferente dos outros grupos submetidos a isquemia quanto às alterações histológicas, peroxidação lipídica e atividade enzimática antioxidante. A creatinina no grupo PCI+HT+IR foi mais baixa comparado ao grupo PCI+IR, mas semelhante ao grupo HT+IR. Conclusões: A combinação de pré-condicionamento local e hipotermia tópica não resultou em proteção à lesão por I/R. Além disso, o PCI local isolado seguido de isquemia quente prejudicou a função renal mais que a isquemia quente isolada. / Purpose: Topical hypothermia and local ischemic preconditioning have been shown to reduce renal ischemia-reperfusion (I/R) injury individually. We examined whether combination of both strategies lessens renal I/R injury. Methods: Post right nephrectomy, 40 male Wistar rats were randomly assigned to five experimental protocols performed in the left kidney: topical hypothermia without ischemia (TH), warm ischemia (IR), ischemic preconditioning followed by warm ischemia (IPC+IR), cold ischemia (TH+IR), and ischemic preconditioning followed by cold ischemia (IPC+TH+IR). Eight randomly assigned right kidneys constituted the control group. After 240 min of reperfusion, the left kidney was retrieved to evaluate histological changes, lipid peroxidation and antioxidant enzymes activity. Serum was collected to evaluate urea and creatinine. Results: IPC+TH+IR group revealed no difference to any other group subjected to ischemia in relation to histological changes, lipid peroxidation and antioxidant enzymes activity. Creatinine was lower in IPC+TH+IR group compared with IPC+IR, but showed no difference compared to TH+IR group. Conclusions: Combination of local ischemic preconditioning (IPC) and topical hypothermia conferred no protection in renal I/R injury. Moreover, local IPC solely followed by warm ischemia impaired renal function more than warm ischemia alone.