Vasorrelaxant effects of R(+)-pulegone were tested in normotensive rats using two different methodological approaches. In vivo, increasing doses (1, 3, 10, 20 and 30 mg / kg) were administered in the animals, i.v. bolus and selected randomly, then the parameters for mean arterial pressure (MAP) and heart rate (HR) were evaluated. In this situation the substance triggered a hypotensive effect and bradycardia. In the ex vivo approach, we used the thoracic aorta of these animals and isometric tension experiments, evaluated the vasorelaxant activity of the substance. The administration of R (+)-pulegone triggered vasorelaxant effect concentration-dependent in both rings with intact endothelium and with this removed, but the substance had the lowest pD2 value in the presence of the endothelium (-3.64 ± 0.06, n = -3.17 vs 5 ± 0.034, n = 6, respectively), no change in peak effect (98.2 ± 1.2%, n = 5 vs. 106.0 ± 8.1%, n = 6) indicating that the substance acts triggering vasodilation in aortic dependent manner and independent of the vascular endothelium. In rings with intact endothelium, the vasorelaxant activity of R(+)-pulegone was not altered in the presence of diclofenac and atropine, but was modified by L-NAME (-3.00 ± 0.016; n=5), HDX (-3.07 ± 0.021; n=5), ODQ (-3.17 ± 0.03; n = 5) and the red ruthenium (-3.14 ± 0.04; n=5) vs control: -3.64 ± 0.06; n = 5. These results suggest that the substance is probably stimulating NO production via the activation of TRP channels. In smooth muscle vascular, R(+)-pulegone inhibited curve calcium concentration-dependent manner (Emax: 10-4 M: 68 9 ± 3.81%; 3x10-4 M: 40.97 ± 8.05%; 10-3 M: 24.79 ± 5.04% and 3x10-3 M: 0.29 ± 0.33%) via calcium channels type L, as in the presence of nifedipine, there was a reduction of the maximum effect (Emax: 93.3 ± 1.7% ; n = 6 vs Emax control: 106.8 ± 8.1%; n = 6 ). Additionally, it was surveyed the participation of for potassium channels, using 4-aminiopiridine, it was seen that the substance has inhibited response by blocking the potassium channels sensitive to voltage (-2.93 ± 0.012 - n = 5 vs control - 3.17 ± 0.034 - n = 6) as well as sensitive to ATP, since, in the presence of glybenclamide, the relaxant response to R(+)-pulegone was also inhibited (-2.94 vs. -3.17 ± 0.012 ± 0.03). Thus, to cause vasorelaxation in normotensive rat thoracic aorta, R(+)-pulegone, stimulates the production of NO in endothelial cells, probably by activating calcium influx via TRP channels. The effect independent of the endothelium is mediated by inhibition of calcium influx, likely through the CaV and for opening potassium channels (KATP and Kv). / O efeito vasorrelaxante de R(+)-pulegona foi estudado em ratos normotensos, utilizando duas abordagens metodológicas. Na avaliação in vivo, doses crescentes (1, 3, 10, 20 e 30 mg/Kg), foram administradas nos animais, via i.v. em bolus de maneira aleatória, posteriormente os parâmetros de pressão arterial média (PAM) e frequência cardíaca (FC) foram avaliados. Nesta situação a substância desencadeou um efeito hipotensor e bradicárdico dependente de dose. Na abordagem ex vivo, utilizou-se a aorta torácica destes animais e avaliou-se a atividade vasorrelaxante da substância. A administração de R(+)-pulegona desencadeou efeito vasorrelaxante, concentração dependente tanto em anéis com endotélio intacto quanto com este removido, porém a substância apresentou o valor do pD2 menor na presença do endotélio (-3,64 ± 0,06, n=5 vs -3,17 ± 0,034, n=6, respectivamente), sem nenhuma alteração no efeito máximo (98,2 ± 1,2%, n=5 vs 106,0 ± 8,1%, n=6), indicando que a substância atua desencadeando vasodilatação na aorta de maneira dependente e independente do endotélio vascular. Em anéis com endotélio intacto, a atividade vasorrelaxante de R(+)-pulegona não foi alterada na presença de diclofenaco e atropina, porém foi modificada por L-NAME (-3,00 ± 0,016, n=5), HDX (-3,07 ± 0,021, n=5), ODQ (-3,17 ± 0,03, n=5) e o vermelho de rutênio (-3,14 ± 0,04, n=5) todos vs controle: -3,64 ± 0,06, n=5. Estes resultados sugerem que a substância provavelmente está estimulando a produção de óxido nítrico (NO), via ativação dos canais TRP na célula endotelial. O efeito dependente do músculo liso vascular de R(+)-pulegona dá-se através da inibição da curva de cálcio de maneira dependente de concentração (Emáx: 10-4 M: 68,9 ± 3,81%; 3x10-4 M: 40,97 ± 8,05%; 10-3 M: 24,79 ± 5,04% e 3x10-3 M: 0,29 ± 0,33%), via canais para cálcio tipo L, pois na presença de NIF, ocorreu redução do efeito máximo (Emáx: 93,3 ± 1,7%, n= 6 vs controle Emáx: 106,8 ± 8,1%, n=6). Adicionalmente, pesquisou-se a participação dos canais para potássio e na presença de 4-AP ocorreu redução da resposta relaxante da substância indicando a participação dos canais para potássio sensíveis a voltagem (-2,93 ± 0,012, n=5 vs controle -3,17 ±0,034, n=6) e também sensíveis ao ATP, uma vez que, na presença de glibenclamida, a resposta relaxante para R(+)-pulegona também foi reduzida (-2,94 ± 0,012, n=5 vs -3,17 ± 0,03, n=6). Assim, para causar vasorrelaxamento em aorta torácica de ratos normotensos, R(+)-pulegona, estimula a produção de NO na célula endotelial, provavelmente por ativar o influxo de cálcio via canais TRP e o efeito independente do endotélio, é mediado pela inibição do influxo de cálcio, provavelmente através dos CaV e abertura dos canais para potássio (Kv e KATP).

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No. of bitstreams: 1 juliocesarmoraeslovisi.pdf: 3660990 bytes, checksum: 9bfd65df440e1a934d906a3918e427d5 (MD5) Previous issue date: 2013-09-09 / INTRODUÇÃO: A epidemia de obesidade e de síndrome metabólica (SM) observada nos últimos anos se associa a uma série de agravos clínicos como neoplasias, diabetes mellitus e doenças cardiovasculares, notadamente a hipertensão arterial (HA). Diversos mecanismos etiopatogênicos têm sido descritos na HA associada à SM entre os quais citam-se a participação da aldosterona (ALDO) e da disfunção endotelial. OBJETIVOS: avaliar os efeitos do bloqueio do receptor mineralocorticoide (RMC) na função endotelial, na pressão arterial (PA) e em parâmetros inflamatórios e renais de indivíduos com SM. PACIENTES E MÉTODOS: Foram selecionados 42 pacientes elegíveis para o protocolo. Todos os voluntários foram submetidos a exame clínico, avaliação laboratorial com dosagens de mediadores inflamatórios e de excreção urinária de albumina, além de avaliação cardiológica, com monitorização ambulatorial da pressão arterial (MAPA), ecocardiograma e estudo da vasodilatação fluxo-mediada (VDFM), antes e após o tratamento. Destes, 28 indivíduos foram tratados com espironolactona (ESPIRO) na dose de 25-50 mg/dia e 14 com amlodipina (AMLO) na dose 5-10 mg/dia por 16 semanas (Resultados 1). Após essa avaliação, com objetivo de homogeneizar os grupos para melhor comparação dos parâmetros de VDFM, inflamatórios e renais, foram selecionados 27 indivíduos alocados em dois grupos por meio da aplicação da técnica do Propensity Score (PS). Deste modo foram constituídos dois grupos homogêneos, a saber: 16 pacientes em um grupo tratado com ESPIRO e 11 no grupo controle, tratados com AMLO, por um período de 16 semanas (Resultados 2). Resultados 1: Os dados iniciais mostraram que o tratamento da HA com ESPIRO e com AMLO resultou em redução significante da PA em ambos os grupos. No grupo ESPIRO foi observado aumento da VDFM, enquanto no grupo AMLO houve redução significativa desse parâmetro. Observamos ainda redução significativa da microalbuminúria e de mediadores inflamatórios no grupo ESPIRO, o que não ocorreu no grupo AMLO. Finalmente, observou- se aumento significativo do colesterol HDL no grupo ESPIRO o que não foi observado no grupo AMLO. Resultados 2: com a aplicação do PS e consequente maior homogeneidade entre os grupos houve a confirmação desses achados nos 2 grupos (ESPIRO e AMLO) e, adicionalmente, permitiu a subdivisão destes em inflamados (PCR>3,0 mg/dL) e não inflamados (PCR < 3,0 mg/dL). Quando se avaliaram a VDFM, o comportamento pressórico e de parâmetros metabólicos e renais observou-se aumento da VDFM, maior redução da PA, aumento do colesterol HDL e redução da albuminúria que foram significativas no grupo ESPIRO, notadamente no subgrupo não inflamado em comparação ao grupo inflamado. CONCLUSÃO: O bloqueio dos RMC em hipertensos com SM melhorou a função endotelial e reduziu a pressão arterial, com impacto favorável sobre marcadores metabólicos, inflamatórios e na excreção urinária de albumina. Estes achados apontam para efeitos benéficos adicionais à redução pressórica em pacientes portadores de SM tratados com bloqueadores dos RMC. / INTRODUCTION: The epidemic of obesity and metabolic syndrome (MS) described in recent years is associated with a series of clinical conditions such as malignancy, diabetes mellitus, and cardiovascular diseases, chiefly systemic arterial hypertension (AH). There are several mechanisms proposed to explain the development of MS-associated AH, among which the role of aldosterone and endothelial dysfunction are noteworthy. OBJECTIVES: assess the effects of mineralocorticoid receptor blockade (MRB) on endothelial function, blood pressure (BP) and inflammatory and renal parameters of individuals with the MS. PATIENTS AND METHODS: Forty-two eligible patients were selected. All volunteers underwent clinical examination, laboratory determination of inflammatory mediators and urinary albumin excretion, and cardiologic examination with 24-hour ambulatory blood pressure (24-h ABPM), echocardiography and assessment of the flow-mediated vasodilation (FMD) at baseline and after treatment. Twenty-eight individuals received spironolactone (SPIRO), 25-50mg/day, and 14 individuals received amlodipine (AMLO), 5-10mg/day, for 16 weeks (Results 1). In order to homogenize the groups and better compare the FMD and the inflammatory and renal parameters, 27 individuals were selected and allocated to two groups according to the propensity score (PS) technique: 16 individuals treated with SPIRO and 11 controls, treated with AMLO, for 16 weeks (Results 2). Results 1: Both SPIRO-treated and AMLO-treated groups had significant BP reductions. While the SPIRO-treated group had increased FMD, the AMLO-treated group had a significant reduction of this parameter. There was also a significant reduction of microalbuminuria and inflammatory mediators in the SPIRO-treated group, but not in the AMLO one. There was a significant increase of HDL-cholesterol in the SPIRO group, but not in the AMLO one. Results 2: With the PS technique, and consequent better homogenization of the groups, we confirmed these findings in the two groups (SPIRO and AMLO) and further subdivided them into those with inflammation (CRP>3.0mg/dl) and those without inflammation (CRP<3.0mg/dl). There were significantly increased FMV, greater BP reduction, increased HDL-cholesterol, and significant reduction of albuminuria in the SPIRO group, notably in the subgroup without inflammation, as compared with that with inflammation. CONCLUSION: MRB in hypertensive subjects with the MS improved endothelial function and reduced blood pressure, with a favorable impact on metabolic and inflammatory markers and on the urinary albumin excretion. These findings point to MRB as a new option for treatment of AH in individuals with the MS.

Cardiac transplantation is governed by complex immunological mechanisms contributing to different types of allograft rejection. Early non-specific graft failure and chronic rejection (cardiac allograft vasculopathy) represent the main limitations for the recipients’ short- and long-term survival respectively. To date, the pathogenesis of both rejection types remains ill-defined. However, it is believed that they are related to an immunologically mediated potent inflammatory process, occurring whether early after transplantation (acute), or lasting for the lifetime of the graft (chronic).<p> <p>The initiating mechanisms of chronic rejection in solid organ transplantation remain ill-defined. Emerging evidence sustains that graft vasculopathy is primarily driven by alloreactive CD4+ T lymphocytes sensitized by the indirect pathway of allorecognition. To date, whereas the nature of APCs involved in this particular pathway has yet to be identified, it appears challenging to speculate that recipient-derived endothelial cells (ECs) repopulating the graft may represent the main cell targets recognized by indirectly primed alloreactive CD4+ T cells to mediate the rejection of cardiac transplants. In the first part of this thesis, we specifically studied the indirect pathway of allorecognition with a transgenic mice (Marilyn mice) model that expresses a T cell receptor (TCR) transgene which recognizes the male antigen H-Y in an I-Ab-restricted fashion. Our results provide evidence that graft endothelium replacement by recipient-type cells expressing MHC Class II molecules is required for the chronic rejection of vascularized cardiac transplants mediated by indirect pathway alloreactive CD4+ T cells.<p><p>The purpose of the second part of the thesis was to investigate the potential implication of interleukin-22 (IL-22), an early phase secreted proinflammatory cytokine of the IL-10 family, in the acute rejection of cardiac allografts. IL-22 was recently described as an effector key modulator of the inflammatory process produced mainly by differentiated CD4+ T cells of the Th17 lineage. As being closely related to IL-10 and IL-17, both involved in the rejection process of vascularized heart allografts, we attempted to determine the precise role of IL-22 in this process. Experiments were conducted with a recently developed murine model deficient for the IL-22 gene (IL-22KO). The results of the second part of the thesis show that IL-22 is not an effector cytokine in cardiac allograft rejection. In contrast, as being early expressed into the allograft, likely IL-22 plays a protective role in the inflammation leading to acute cardiac rejection, probably depending on a neutrophil-related mechanism. <p><p><p>In conjunction with current understanding of inflammatory and antigen-specific events in allografts, overall, our results provide new insights into the mechanisms of chronic and acute cardiac rejection, thus prompting to further interrogations and appealing novel therapeutic strategies. Pharmacologic manipulation of endothelium is challenging. Given their capacity to sense and rapidly respond to the local environment, ECs are the ideal targets for rapid systemic delivery of therapeutic agents. Combination therapy is required to reduce inflammatory reaction and endothelial activation, to modulate endothelial dysfunction and promote endothelial survival. Also, given that IL-22 may alleviate tissue destruction during inflammatory responses, therapies that enhance its production and protective action in the transplanted organs seem attractive to specifically affect tissue responses, without exerting direct effects on the immune response.<p><p><p> / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Arterial occlusive diseases are major causes of morbidity and mortality in industrialized countries and represent a huge economic burden. The extent of the native collateral circulation is an important determinant of blood perfusion restoration and therefore the severity of tissue damage and functional impairment that ensues following arterial occlusion. Understanding the mechanisms responsible for collateral artery development may provide avenues for therapeutic intervention. Here, we identify a critical requirement for mixed lineage kinase (MLK) – cJun-NH2-terminal kinase (JNK) signaling in vascular morphogenesis and native collateral artery development. We demonstrate that Mlk2-/-Mlk3-/- mice or mice with compound JNK-deficiency in the vascular endothelium display abnormal collateral arteries, which are unable to restore blood perfusion following arterial occlusion, leading to severe tissue necrosis in animal models of femoral and coronary artery occlusion. Employing constitutive and inducible conditional deletion strategies, we demonstrate that endothelial JNK acts during the embryonic development of collateral arteries to ensure proper patterning and maturation, but is dispensable for angiogenic and arteriogenic responses in adult mice. During developmental vascular morphogenesis, MLK – JNK signaling is required for suppression of excessive sprouting angiogenesis likely via JNK-dependent regulation of Dll4 expression and Notch signaling. This function of JNK may underlie its critical requirement for native collateral artery formation. Thus, this study introduces MLK – JNK signaling as a major regulator of vascular development. In contrast, we find that JNK in hematopoietic cells, which are thought to share a common mesodermally-derived precursor with endothelial cells, is cellautonomously dispensable for normal hematopoietic development and hematopoietic stem cell self-renewal, illustrating the highly context dependent function of JNK.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Introdução: Apesar de bons resultados descritos na literatura, o substituto ideal para a utilização como remendo no fechamento arterial ainda não existe. Por este motivo, ainda há espaço para a busca por remendo que seja biocompatível, e que apresente facilidade de manuseio e resultados satisfatórios. Avaliamos remendos arteriais de silicone (polidimetilsiloxano com reforço em poliéster - PDMSr) em comparação com remendos arteriais de PTFEe. Objetivo: O objetivo deste trabalho é comparar, em modelo experimental, em coelhos, os resultados de remendos arteriais feitos em PDMSr com remendos de PTFEe. Materiais e Método: A amostra foi definida em 10 animais que completassem todas as etapas da pesquisa em cada grupo. Os animais foram submetidos à laparotomia mediana e abertura longitudinal da aorta de aproximadamente 8mm, realizando-se o seu fechamento com remendo do grupo selecionado, seguido do fechamento por planos. Os animais foram mantidos em biotério até o 60º PO, quando, então, realizou-se arteriografia de controle, e análise macro e microscópica de peça. Resultados: Para se atingir a amostra desejada, foram necessários 12 procedimentos no grupo PDMSr e 16 no grupo PTFEe. Ocorreram 2 óbitos no grupo PDMSr e 6 no grupo PTFEe. Apesar do número maior de óbitos no grupo PTFEe não houve diferença estatística na sobrevida entre os grupos. Um animal do grupo PDMSr apresentou monoparesia em pata posterior direita e um animal do grupo PTFEe apresentou hérnia incisional. Não houve diferença estatística nas complicações entre os grupos. O tempo operatório foi estatisticamente maior no grupo PTFEe quando comparamos todos os animais, fato que não se repetiu quando excluímos os animais que faleceram. O peso e o tempo operatório foram estatisticamente maiores nos animais que morreram. Todos os animais que chegaram ao final do tempo de estudo apresentavam aorta patente. Na análise macroscópica da peça, houve, estatisticamente, maior reação tecidual periprótese no grupo PTFEe. A microscopia eletrônica de varredura evidenciou cobertura de todo o remendo de PDMSr por tecido similar ao endotélio, enquanto, nos remendos de PTFEe, o crescimento limitou-se às bordas da linha de sutura e ilhas isoladas no seu centro. Conclusão: O material estudado apresentou resultados comparáveis ao do PTFEe, porém com menor reação tecidual local e maior proliferação celular para a luz do vaso. Apesar de novos estudos serem necessários, inclusive para avaliação de uso em humanos, o presente estudo apresenta resultados promissores que encorajam a continuidade de sua pesquisa / Introduction: Although good results are reported for various materials for use as patches for arterial closure, as yet none of these is ideal. Therefore, research is continuing into development of a patch that is biocompatible and provides ease of handling, while having satisfactory outcomes. A new silicone arterial patch (polydimethylsiloxane reinforced with polyester fabric, PDMSr) was compared with patches made of expanded polytetrafluoroethylene (ePTFE). Objective: To compare the outcomes between arterial patches made of PDMSr with those made of ePTFE, in an experimental rabbit model. Materials and Method: Rabbits were placed in two groups, and received either PDMSr or ePTFE arterial patches (PDMSr group and ePTFE group, respectively). The animals underwent laparotomy and longitudinal opening of the aorta, which was then closed with the selected patch, followed by suture of all layers. The animals were kept in their cages until the 60th postoperative day, when arteriography, removal of the aorta, and macroscopic and optic and scanning electron microscopic analyzes of the aorta were performed. Ten rabbits from each group that had completed all stages of the research were included in analyses. Results: Twelve procedures were performed in the PDMSr group and 16 in the ePTFE group. There were 2 deaths in the PDMSr group and 6 in the ePTFE group. Despite the higher number of deaths in the ePTFE group, there was no statistical difference in survival rate between the groups. One animal in the PDMSr group developed monoparesis in its right hind paw and 1 animal in the ePTFE group had an incisional hernia. There was no statistical difference in complications between the groups. The operative time was significantly longer in the ePTFE group when all animals were included in analysis, but not when animals that died were excluded. Body weight was significantly greater and operative time was significantly longer in animals that died. Postsurgical aortic patency in the survival animals was 100% in both groups by arteriography. Macroscopically, tissue reaction around the prosthesis was greater in the ePTFE group (statistically significant). Microscopically, the PDMSr patches were entirely covered with a cellular endothelium-like tissue, while tissue growth on the ePTFE patches was limited to the edges of the suture line and to isolated central islands. Conclusion: The two materials showed comparable outcomes; however, PDMSr showed cellular proliferation to the entire graft, and less local inflammatory reaction compared with ePTFE. Although further studies are required, including assessment in humans, the results of the present study indicate that PDMSr shows promise as an arterial patch material

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

No description available.

Introdução: Apesar de bons resultados descritos na literatura, o substituto ideal para a utilização como remendo no fechamento arterial ainda não existe. Por este motivo, ainda há espaço para a busca por remendo que seja biocompatível, e que apresente facilidade de manuseio e resultados satisfatórios. Avaliamos remendos arteriais de silicone (polidimetilsiloxano com reforço em poliéster - PDMSr) em comparação com remendos arteriais de PTFEe. Objetivo: O objetivo deste trabalho é comparar, em modelo experimental, em coelhos, os resultados de remendos arteriais feitos em PDMSr com remendos de PTFEe. Materiais e Método: A amostra foi definida em 10 animais que completassem todas as etapas da pesquisa em cada grupo. Os animais foram submetidos à laparotomia mediana e abertura longitudinal da aorta de aproximadamente 8mm, realizando-se o seu fechamento com remendo do grupo selecionado, seguido do fechamento por planos. Os animais foram mantidos em biotério até o 60º PO, quando, então, realizou-se arteriografia de controle, e análise macro e microscópica de peça. Resultados: Para se atingir a amostra desejada, foram necessários 12 procedimentos no grupo PDMSr e 16 no grupo PTFEe. Ocorreram 2 óbitos no grupo PDMSr e 6 no grupo PTFEe. Apesar do número maior de óbitos no grupo PTFEe não houve diferença estatística na sobrevida entre os grupos. Um animal do grupo PDMSr apresentou monoparesia em pata posterior direita e um animal do grupo PTFEe apresentou hérnia incisional. Não houve diferença estatística nas complicações entre os grupos. O tempo operatório foi estatisticamente maior no grupo PTFEe quando comparamos todos os animais, fato que não se repetiu quando excluímos os animais que faleceram. O peso e o tempo operatório foram estatisticamente maiores nos animais que morreram. Todos os animais que chegaram ao final do tempo de estudo apresentavam aorta patente. Na análise macroscópica da peça, houve, estatisticamente, maior reação tecidual periprótese no grupo PTFEe. A microscopia eletrônica de varredura evidenciou cobertura de todo o remendo de PDMSr por tecido similar ao endotélio, enquanto, nos remendos de PTFEe, o crescimento limitou-se às bordas da linha de sutura e ilhas isoladas no seu centro. Conclusão: O material estudado apresentou resultados comparáveis ao do PTFEe, porém com menor reação tecidual local e maior proliferação celular para a luz do vaso. Apesar de novos estudos serem necessários, inclusive para avaliação de uso em humanos, o presente estudo apresenta resultados promissores que encorajam a continuidade de sua pesquisa / Introduction: Although good results are reported for various materials for use as patches for arterial closure, as yet none of these is ideal. Therefore, research is continuing into development of a patch that is biocompatible and provides ease of handling, while having satisfactory outcomes. A new silicone arterial patch (polydimethylsiloxane reinforced with polyester fabric, PDMSr) was compared with patches made of expanded polytetrafluoroethylene (ePTFE). Objective: To compare the outcomes between arterial patches made of PDMSr with those made of ePTFE, in an experimental rabbit model. Materials and Method: Rabbits were placed in two groups, and received either PDMSr or ePTFE arterial patches (PDMSr group and ePTFE group, respectively). The animals underwent laparotomy and longitudinal opening of the aorta, which was then closed with the selected patch, followed by suture of all layers. The animals were kept in their cages until the 60th postoperative day, when arteriography, removal of the aorta, and macroscopic and optic and scanning electron microscopic analyzes of the aorta were performed. Ten rabbits from each group that had completed all stages of the research were included in analyses. Results: Twelve procedures were performed in the PDMSr group and 16 in the ePTFE group. There were 2 deaths in the PDMSr group and 6 in the ePTFE group. Despite the higher number of deaths in the ePTFE group, there was no statistical difference in survival rate between the groups. One animal in the PDMSr group developed monoparesis in its right hind paw and 1 animal in the ePTFE group had an incisional hernia. There was no statistical difference in complications between the groups. The operative time was significantly longer in the ePTFE group when all animals were included in analysis, but not when animals that died were excluded. Body weight was significantly greater and operative time was significantly longer in animals that died. Postsurgical aortic patency in the survival animals was 100% in both groups by arteriography. Macroscopically, tissue reaction around the prosthesis was greater in the ePTFE group (statistically significant). Microscopically, the PDMSr patches were entirely covered with a cellular endothelium-like tissue, while tissue growth on the ePTFE patches was limited to the edges of the suture line and to isolated central islands. Conclusion: The two materials showed comparable outcomes; however, PDMSr showed cellular proliferation to the entire graft, and less local inflammatory reaction compared with ePTFE. Although further studies are required, including assessment in humans, the results of the present study indicate that PDMSr shows promise as an arterial patch material