• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 413
  • 223
  • 155
  • 36
  • 34
  • 29
  • 21
  • 11
  • 8
  • 5
  • 5
  • 4
  • 3
  • 3
  • 2
  • Tagged with
  • 1132
  • 231
  • 170
  • 170
  • 169
  • 159
  • 149
  • 146
  • 140
  • 120
  • 118
  • 114
  • 95
  • 84
  • 81
  • 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.
371

Synthèse de nanoparticules spécifiques pour le ciblage et l'imagerie de l'angiogenèse tumorale

Deshayes, Stéphanie 16 December 2009 (has links)
La croissance d’une tumeur requiert la formation de son propre réseau vasculaire par angiogenèse. Ce processus est orchestré par une multitude de médiateurs dont le VEGF (Vascular Endothelial Growth Factor) qui interagit avec des récepteurs surexprimés à la surface des cellules endothéliales des vaisseaux avoisinant la tumeur. Les thérapies ciblées anticancéreuses jouent sur cette surexpression pour concevoir de nouvelles molécules spécifiques de la zone tumorale. Un nouvel agent de ciblage a ainsi vu le jour au sein du laboratoire. Il s’agit d’un cyclopeptide de 17 acides aminés, nommé CBO-P11 qui présente une haute affinité pour les récepteurs du VEGF. Afin de prolonger le temps de circulation du peptide dans le sang, des nanoparticules de poly(fluorure de vinylidène) (PVDF), polymère biocompatible, ont été utilisées comme vecteur. Les nanoparticules ont tout d’abord été synthétisées par une polymérisation radicalaire en émulsion dans l’eau, puis radio-greffées avec de l’acide acrylique (AA) pour obtenir du PVDF-g-PAA, ce qui a permis par la suite de les fonctionnaliser avec le CBO-P11 et un agent d’imagerie par « click » chemistry via un bras espaceur de type oligo(éthylène glycol). Différents marqueurs ont été étudiés à savoir deux sondes fluorescentes pour l’imagerie optique et un agent de contraste pour l’imagerie par résonance magnétique à bas champ. Chaque étape de synthèse a été caractérisée par de nombreuses techniques telles que la diffusion statique et dynamique de la lumière, la diffusion de neutrons aux petits angles, la spectrométrie photoélectronique de rayons X, la spectrométrie infrarouge, la spectrométrie de fluorescence et la polarisation dynamique nucléaire. Des études in vitro sur des cellules endothéliales ont permis de montrer que les nanoparticules n’étaient pas cytotoxiques et que le CBO-P11 lié au vecteur conservait sa spécificité pour les récepteurs du VEGF. Ces outils multifonctionnels présentent un grand potentiel pour cibler et imager les zones tumorales. / Tumor growth requires the formation of its own vascular network by angiogenesis. This process is mediated through numerous factors including VEGF (Vascular Endothelial Growth Factor) which interacts with receptors overexpressed on endothelial cells of blood vessels neighboring tumor. Targeted anticancer therapies take advantage of this overexpression to design tumor-specific molecules. A new targeting agent, CBO-P11 was synthesized in the laboratory. It is a 17-mer cyclopeptide with a high affinity for VEGF receptors. In order to increase the blood circulation time of this peptide, nanoparticles of poly(vinylidene fluoride) (PVDF), biocompatible polymer, were used as carrier. Nanoparticles were synthesized by radical polymerization in aqueous emulsion, then radio-grafted with acrylic acid (AA) to obtain PVDF-g-PAA. Nanoparticles were functionalized with CBO-P11 and an imaging agent by “click” chemistry via an oligo(ethylene glycol)-like spacer arm. Different dyes were used: two fluorescent probes for optical imaging and a contrast agent for low-field magnetic resonance imaging. Each step of the nanoparticles preparation was monitored and successfully characterized by numerous techniques such as dynamic and static light scattering, small-angle neutron scattering, X-ray photoelectron spectroscopy, infrared spectroscopy, fluorescence spectroscopy and dynamic nuclear polarization. In vitro studies were performed on endothelial cells and have shown that nanoparticles were not cytotoxic and that CBO-P11 conjugated to nanoparticles kept its specificity for VEGF receptors. Those multifunctional tools offer a great potential to target and image tumor.
372

The effect of hyperstimulation on vascular endothelial growth factor (VEGF) and cyclooxygenase 2 (COX2) in the rat uterus in early pregnancy

Strkalj, Mirjana 02 September 2008 (has links)
ABSTRACT Vascular permeability and angiogenesis are crucial events in the rodent and human uterus in early pregnancy and are regulated by vascular endothelial growth factor (VEGF) and prostaglandins liberated from arachidonic acid by cyclooxygenase 2 (COX2). These events coincide with the typical morphological features of the receptive uterus and are regulated by synchronized release of ovarian hormones (oestrogen and progesterone). However, administration of follicle stimulating hormone (FSH) and human chorionic gonadotropin (hCG), commonly used in assisted reproduction, affect the synchrony of the hormonal milieu, particularly by increasing oestrogen levels. This causes detrimental changes to the uterine morphology and affects vascular permeability at the site of implantation. In the present study, the expression of COX2 and VEGF was compared between control and hyperstimulated rat uteri during the peri-implantation period using immunohistochemistry and Western blot analysis. While in control pregnant rats COX2 and VEGF immunolocalization occurred in the luminal epithelial cells and stroma on consecutive days, strong immunolocalization of COX2 and VEGF occurred in the luminal epithelial cells but was inhibited in the stroma of the hyperstimulated rats. This appears to have resulted in the suppression of stromal decidualization and vascular permeability. Western blot analysis did not show any results. This may be due to low concentrations of the protein in the sample. Since vascular permeability and angiogenesis are critical to the process of implantation and are influenced by VEGF and COX2, disturbance of the pattern of these two proteins by hyperstimulation may contribute to the low implantation rate in IVF programes. immunohistochemistry and Western blot analysis. While in control pregnant rats COX2 and VEGF immunolocalization occurred in the luminal epithelial cells and stroma on consecutive days, strong immunolocalization of COX2 and VEGF occurred in the luminal epithelial cells but was inhibited in the stroma of the hyperstimulated rats. This appears to have resulted in the suppression of stromal decidualization and vascular permeability. Western blot analysis did not show any results. This may be due to low concentrations of the protein in the sample. Since vascular permeability and angiogenesis are critical to the process of implantation and are influenced by VEGF and COX2, disturbance of the pattern of these two proteins by hyperstimulation may contribute to the low implantation rate in IVF programes.
373

Efeito in vitro da botropasina, uma metaloproteinase do veneno da serpente Bothrops jararaca, e de seus domínios não catalíticos sobre eventos envolvidos na angiogênese / In vitro effect of bothropasin, an snake venom metalloproteinase from Bothrops jararaca, and its non-catalytic domains on events involved in angiogenesis

Molina, Miryam Guillermina Palomino Rodriguez 09 November 2018 (has links)
Botropasina (Bt) é uma toxina isolada do veneno da serpente Bothrops jararaca, associada a processos inflamatórios. Neste contexto da inflamação como fator desencadeante da angiogênese, verificamos se a botropasina, uma metaloproteinase isolada do veneno da serpente Bothrops jararaca, poderia modular diretamente as transições fenotípicas do processo angiogênico. O objetivo deste trabalho foi caracterizar os efeitos da Botropasina, domínios DC e peptídeos sintéticos derivados dos domínios DC (Ca II, Ca III e HCR), sobre os eventos da angiogênese como proliferação, migração, secreção de gelatinases, tubulogênese, e os mecanismos moleculares envolvidos no sistema in vitro nas células endoteliais HUVEC-CS. Nossos resultados mostram que tanto as proteínas Bt e DC, e o peptídeo HCR induzem os eventos angiogênicos de proliferação, migração, secreção de MPPs e formação de túbulos em matrigel, e estes são dependentes da dose. Os peptídeos Ca II e Ca III não induziram todas as características próprias da angiogênese. A migração observada tanto nos ensaios 2D, 3D, assim como na expressão do DLL4 e as fibras de estresse do citoesqueleto, sugerem que o tratamento com botropasina e o peptídeo HCR induzem o fenótipo migratório - tip cells nas células endoteliais. A ativação da via de sinalização de Erk via integrinas, seria o mecanismo de sinalização das proteínas Bt e DC, enquanto o peptídeo linear HCR teria um mecanismo de interação direta com receptores intracelulares. O tratamento com a Bt estimula a fosforilação das proteínas Akt, Fak e p38, envolvidas na migração, sobrevida e estresse celular, mas sem alterações na morfologia. A presença de proteínas inflamatórias como vimentina e calistatina nas formas secretada, indica que os tratamentos com as proteínas Bt e DC induzem uma resposta inflamatória nas células endotelias, promovendo os eventos da angiogênese, enquanto o peptídeo HCR se mostra como altamente mitogênico e sem efeitos inflamatórios. / Botrophasin (Bt) is a metalloproteinase isolated from Bothrops jararaca snake venom, an associated with inflammatory processes. In the context of inflammation as a triggering factor of angiogenesis, we tested if botropasin, could directly modulate the phenotypic transitions of the angiogenic process. The objective of this work was to characterize the effects of Botropasin, DC domains and synthetic peptides derived from the DC domains (Ca II, Ca III and HCR), on the events of angiogenesis such as proliferation, migration, gelatinases secretion, tubulogenesis, and molecular mechanisms involved in the in vitro system in HUVEC-CS endothelial cells. Our results show that both Bt, DC proteins, and the HCR peptide induce the angiogenic events of proliferation, migration, MPP secretion and matrigel tubule formation, and these are dose dependent. Ca II and Ca III peptides did not induce all the angiogenesis characteristics. The migration observed in both the 2D and 3D assays, as well as in the expression of DLL4 and cytoskeletal stress fibers, suggests that treatment with bothropasin and the HCR peptide induce the migratory phenotype - tip cells in the endothelial cells. Activation of the Erk signaling pathway via integrins would be the signaling mechanism for Bt and DC proteins, whereas the linear peptide HCR would have a mechanism of direct interaction with intracellular receptors. Treatment with Bt stimulates the phosphorylation of Akt, Fak and p38 proteins, involved in migration, survival and cell stress, but without changes in morphology. The presence of inflammatory proteins such as secreted vimentin and kallistatin indicates that the treatments with Bt and DC proteins induce an inflammatory response in the endothelial cells, promoting the angiogenesis events, whereas the HCR peptide shows to be highly mitogenic and without inflammatory effects.
374

Semaphorin 3F as a novel therapeutic option in the fight against pancreatic cancer

Niclou, Benoit 24 July 2018 (has links)
INTRODUCTION: Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive form of cancer with a high mortality rate, primarily due to lack of effective treatment options. Current therapeutic approaches are limited to surgical resection of the pancreas during early stages of the disease and to the use of non-specific chemotherapeutic drugs such as gemcitabine, neither of which has successfully improved the 5-year survival rate of PDAC. Both the lack of effective treatments and the high mortality of the disease call for the urgent need to develop new therapeutic options. OBJECTIVES: This thesis project focuses on an endogenous inhibitor of the neuropilin 2 receptor (NRP2) called semaphorin 3F (SEMA3F) and its use as a potential new drug in the fight against pancreatic cancer. By binding the transmembrane receptor neuropilin 2 (NRP2), SEMA3F can inhibit angiogenesis and cellular proliferation. Interestingly, given its role as a guidance molecule, it is also a potent mediator of cellular repulsion. All three of these effects will be analyzed in the context of this study. METHODS: Syngeneic pancreatic cancer cells were injected orthotopically in two separate groups of mice. One group involved the use of transgenic Nrp2-/- mice, and served as a way to analyze the absence of the receptor on the vasculature and how that affects the growth of the primary tumor and the formation of metastases in the liver. The other group received intravenous injections of SEMA3F-expressing and control adenovirus, and served to explore the effect of SEMA3F as a potential therapy against the growth of the primary tumor in the pancreas and distant metastases in the liver. RESULTS: We observed a decrease in pancreatic tumor and metastatic growth in the absence of Nrp2 in our transgenic mouse model compared to the WT control. Mice injected with SEMA3F-expressing adenovirus also showed a decrease in primary tumor growth as well as a reduction in the formation of metastases in the liver compared to the control. CONCLUSION: Nrp2 mediates angiogenesis in pancreatic cancer, which facilitates the growth of the primary tumor as well as the formation of metastases. Our results indicate that the anti-angiogenic, anti-proliferative and repulsive actions of SEMA3F could be used to develop an effective treatment option for PDACpancreatic ductal adenocarcinoma. / 2020-07-24T00:00:00Z
375

Efeito de SMADs<i/> e de microRNAs na expressão gênica de TGF-&#946;1 e seu papel na angiogênese em pacientes com mielofibrose e trombocitemia essencial / Effects of SMADs and microRNAs in TGF-&#946;1 gene expression and its role in the angiogenesis pathophysiology in myelofibrosis and essential thrombocythemia patients.

Nunes, Daniela Prudente Teixeira 07 August 2015 (has links)
OBJETIVO: Investigar o efeito da expressão de RNAm dos SMADs e de microRNAs (miRNAs) que possuem o TGFB1 como alvo na expressão gênica (RNAm e proteína) de TGF-&#946;1 e seu papel na fisiopatologia da angiogênese em pacientes com mielofibrose (MF) e trombocitemia essencial (TE). MÉTODOS: Foram incluídos 21 pacientes com MF primária (MFP), 21 com MF pós-TE (MFPTE) e 24 com TE, além de 98 indivíduos controles pareados de acordo com gênero e idade com os pacientes. As análises realizadas no sangue periférico foram: quantificação das concentrações plasmáticas e de RNAm de TGFB1, VEGFA e FGF2; quantificação de RNAm de SMADs 1 a 7 e de miRNAs 193a-5p, 369-5p, 542-5p, 590-3p, e 590- 5p; e detecção das mutações JAK2V617F (com quantificação alélica), MPLW515K/L e CALR. Em 26 biópsias de medula óssea dos pacientes, foram determinados o grau de microvasculatura (angiogênese estimada - CD34), a imunoexpressão de TGF-b1 ativo, TGF-&#946;1 latente e c-MPL. RESULTADOS: As concentrações de TGF- &#946;1 plasmático foram semelhantes entre os pacientes e controles, enquanto o VEGFA plasmático foi maior em todos os grupos de pacientes comparados aos seus controles. O FGF2 plasmático também foi maior em todos os grupos de pacientes, e a expressão de seu RNAm foi maior nos pacientes com TE do que em seus controles. As expressões de SMADs e de miRNAs foram semelhantes entre pacientes e controles. TGF-&#946;1 e FGF2 plasmáticos apresentaram correlações positivas nos pacientes com MFP, e correlações negativas nos seus controles, assim como nos controles de MFPTE. Em todos os grupos estudados foi observada correlação positiva entre TGF-&#946;1 e VEGFA plasmáticos. Além disso, foram demonstrados diferentes perfis de correlações entre a expressão gênica de TGF-&#946;1 e os diversos SMADs e miRNAs em cada grupo de pacientes e controles. Os pacientes com MFP com maior angiogênese (de acordo com a mediana da concentração plasmática de VEGFA e FGF2) apresentaram maiores concentrações plasmáticas de TGF-&#946;1 do que aqueles com menor angiogênese. A angiogênese medular estimada (CD34) não foi diferente entre os três grupos de pacientes estudados. Além disso, não foram encontradas correlações entre a imunoexpressão de CD34 e as expressões de RNAm de TGFB1, VEGFA e FGF2 medulares nem em leucócitos de sangue periférico, ou a concentrações plasmáticas de TGF-&#946;1, VEGFA e FGF2. As imunoexpressões de TGF-b1 ativo, TGF-&#946;1 latente e c-MPL foram semelhantes entre os três grupos de pacientes. As frequências das mutações avaliadas foram similares às descritas na literatura. Os pacientes com MFPTE portadores de mutação CALR apresentaram menores concentrações plasmáticas de VEGFA e FGF2 do que os JAK2V617F positivos, enquanto os pacientes com TE portadores de mutação CALR exibiram menores concentrações plasmáticas de TGF-&#946;1 do que os portadores de JAK2V617F. CONCLUSÕES: O presente trabalho permitiu confirmar a correlação positiva entre o TGF-&#946;1 com outros dois marcadores de angiogênese (VEGFA e FGF2). As expressões de SMADs e de miRNAs estudados foram semelhantes entre pacientes e controles, visto não haver diferenças na expressão gênica de TGF-&#946;1. Entretanto, disparidades encontradas nas correlações entre a expressão gênica de TGF-&#946;1 e diferentes SMADs e miRNAs nos pacientes e controles poderiam indicar que a regulação da expressão gênica de TGF-&#946;1 nas doenças estudadas seja distinta da apresentada nos indivíduos sem essas doenças. / AIM: To investigate the effects of the expression of SMADs mRNA and microRNAs (miRNAs) that target TGFB1 in TGF-&#946;1 gene expression (mRNA and protein) and its role in the angiogenesis pathophysiology in myelofibrosis (MF) and essential thrombocythemia (ET) patients. METHODS: Twenty-one primary MF (PMF), twenty-one MF post-ET (MPET) and twenty-four ET patients were included, besides 98 controls matched for gender and age with patients. In peripheral blood were assessed: TGF-&#946;1, VEGFA and FGF2 plasmatic levels and mRNA quantification; SMADs 1 to 7 mRNA quantification and miRNAs 193a-5p, 369-5p, 542-5p, 590-3p, and 590-5p quantification; and detection of JAK2V617F (and allele burden), MPLW515K/L and CALR mutations. Estimated angiogenesis (microvessel grade - CD34), active TGF-b1, latent TGF-&#946; and c-MPL immunoexpression were determined in 26 bone marrow biopsies. RESULTS: Plasmatic TGF-&#946;1 levels were similar in patients and controls, while all the patients groups had higher plasmatic VEGFA than controls. Plasmatic FGF2 was higher in all the patients groups, and its mRNA expression was higher in ET patients than in controls. No differences in SMADs and miRNAs expression were found between patients and controls. There was a positive correlation between plasmatic TGF-&#946;1 and FGF2 in PMF, and a negative correlation between these variables in their controls, as well as in MPET controls. In all studied groups, there was a positive correlation between plasmatic TGF-&#946;1 and VEGF. In addition, different profiles of correlations were demonstrated between TGF-&#946;1 gene expression and the several SMADs and miRNAs studied in each group of patients and controls. PMF patients with higher angiogenesis (according to the median of VEGFA and FGF2 plasma levels) had higher plasmatic TGF-&#946;1 levels than those with lower angiogenesis. Estimated angiogenesis (CD34) in bone marrow biopsies were not different among PMF, MPET and ET patients. Moreover, there were no correlation between CD34 immunoexpression and TGFB1, VEGFA and FGF2 mRNA bone marrow or peripheral blood expression or plasmatic levels, as well as latent TGF-&#946;1, active TGF-b1, and c-MPL immunoexpression were similar in patients studied groups. The frequencies of evaluated mutations were similar to previously reported. MPET patients harboring CALR mutations had lower plasmatic VEGFA and FGF2 than JAK2V617F mutated, while ET patients carrying CALR mutations had lower plasmatic TGF-&#946;1 than JAK2V617F mutated. CONCLUSIONS: This study confirmed the positive correlation among TGF-&#946;1 and two other markers of angiogenesis (VEGFA and FGF2). SMADs and miRNAs expressions were similar between patients and controls, since there were no differences in TGF-&#946;1 gene expression between patients and controls. However, disparities found in the correlations between TGF-&#946;1 gene expression and different SMADs and miRNAs in patients and controls may indicate that TGF-&#946;1 gene expression regulation in studied diseases is distinct from those presented by individuals without these diseases.
376

Avaliação do papel de galectina-3 no recrutamento de macrófagos e sua participação na angiogênese em modelo de fibrossarcoma / Evaluation of the role of galectin-3 in macrophage recruitment and its participation in angiogenesis in a fibrosarcoma model

Furuzawa, Karina Mie 04 November 2016 (has links)
Assim como tecidos normais, tumores possuem uma demanda de nutrientes e oxigênio, suprida através da vasculatura a eles associada que resulta do processo de angiogênese. Fatores pró-angiogênicos são capazes de atrair monócitos, os quais se diferenciam em macrófagos associados a tumores (TAMs). TAMs comumente apresentam fenótipo M2, cujas características são consideradas pró-tumorais, como a promoção da angiogênese e a degradação de matriz extracelular. Estudos indicam que galectina-3 (gal-3), uma proteína pleiotrópica que se liga a ?-galactosídeos, participa do controle da angiogênese e da infiltração de macrófagos M2 na massa tumoral, mas pouco se sabe sobre os mecanismos envolvidos. No presente estudo, utilizamos um modelo de sarcoma induzido por carcinógeno em camundongos selvagens (WT) e knockout para gal-3 (Gal- 3 KO). Comparando os tumores de animais WT e Gal-3 KO, não observamos diferenças no padrão de crescimento tumoral, na área necrótica relativa, na proliferação celular e na quantificação de fibras de colágeno. Demonstramos que, embora ambos os grupos desenvolvam tumores, a angiogênese foi inibida em um microambiente desprovido de gal-3. Entretanto, não houve diferença na produção do fator de crescimento endotelial vascular (VEGF). As imagens obtidas in vivo indicaram que gal- 3 também influencia na formação estrutural de vasos adjacentes ao tumor. Além de mediar aspectos morfológicos relacionados à angiogênese, demonstramos que gal-3 também contribuiu para a funcionalidade vascular, pois houve uma redução na velocidade de fluxo sanguíneo nos vasos intratumorais de animais Gal-3 KO. Nossos dados sugeriram que há menos macrófagos no tumor que não expressa gal-3 e, dentre os TAMs, há mais M2 em comparação ao tumor gal-3-positivo. A análise do tecido onde o tumor se desenvolve, na fase inicial da tumorigênese, indicou que a ausência de gal-3 está relacionada a uma maior densidade de macrófagos M2. Considerando que a presença maior de macrófagos M2 nos sarcomas gal-3-negativos não resultou em maior produção de VEGF, mas sim na inibição da angiogênese, nossos resultados apontam para uma participação significativa de gal-3 na mediação da angiogênese pelos macrófagos / As well as normal tissues, tumors require nutrients and oxygen, which are supplied by the associated vasculature that results from the process of angiogenesis. Pro-angiogenic factors are able to attract monocytes and they differentiate into tumor-associated macrophages (TAMs). TAMs commonly exhibit M2 phenotype, which has characteristics considered pro-tumoral, such as angiogenesis promotion and degradation of extracellular matrix. Studies show that galectin-3 (gal-3), a pleiotropic ?-galactosidebinding protein, participates in angiogenesis control and M2 macrophage infiltration into the tumor mass, but little is known about the mechanisms involved. In this work, we established a model of carcinogen-induced sarcoma in wild-type (WT) and gal-3 knockout (Gal-3 KO) mice. Comparing tumors from WT and Gal-3 KO animals, there were no differences in the pattern of tumor growth, relative necrotic area, cell proliferation and collagenous fibers. We demonstrated that, although both groups develop tumors, angiogenesis was inhibited in a microenvironment devoid of gal-3. However, there was no difference in the production of vascular endothelial growth factor (VEGF). The images obtained in vivo indicated that gal-3 also influenced the structural formation of vessels adjacent to the tumor. In addition to mediating morphological aspects related to angiogenesis, we demonstrated that gal-3 also contributes to vascular functionality, since there was a reduction in blood flow velocity in intratumoral vessels from Gal-3 KO animals. Our data suggested that there are fewer macrophages in tumors without gal-3 and, among TAMs, there are more M2 compared to gal-3-positive tumors. Analysis of the tissue where the tumor develops, in early stages of tumorigenesis, indicated that the lack of gal-3 is related to an increased density of M2 macrophages. Since the greater number of M2 macrophages in gal-3-negative fibrosarcomas did not result in increased VEGF production, but inhibited angiogenesis, our results suggest a significant role of gal-3 in regulation of angiogenesis by macrophages
377

Estudo das expressões imunoistoquímicas dos marcadores HIF-1, VEGF e PDGF-C correlacionados com a angiogênese e o prognóstico em glioblastomas / Study of immunohistochemical expressions on the HIF-1, VEGF and PDGF-C markers, correlated to angiogenesis and to glioblastoma prognosis

Clara, Carlos Afonso 09 May 2011 (has links)
O glioblastoma multiforme (GBM) é o tumor mais agressivo do Sistema Nervoso Central (SNC) e caracteriza-se por um alto poder angiogênico que está diretamente relacionado com a capacidade invasiva e inversamente com o prognóstico. A angiogênese contribui para a malignidade por prover a oxigenação e o suprimento nutricional necessários para o crescimento e invasão do tumor. O GBM prolifera sob um ambiente de hipóxia e o fator induzido por hipóxia (HIF-1) apresenta um papel fundamental na ativação da transcrição de genes alvo que favorecem a angiogênese e evitam a morte celular. O fator de crescimento do endotélio vascular (VEGF) e o fator de crescimento derivado da plaqueta C (PDGF-C) são agentes de grande interesse na angiogênese tumoral e que podem ser modulados pelo HIF-1. Foi realizado tissue microarray(TMA) de 208 casos de GBM e estudados pelo método de imunoistoquímica os marcadores HIF-1, VEGF e PDGFC. Os resultados foram correlacionados com a angiogênese avaliada através da densidade microvascular (DMV) pelo CD34, CD105, VEGF e PDGF-C, com a proliferação celular endotelial através da marcação nuclear pelo KI-67 e também com a sobrevida. A expressão tumoral do HIF-1 foi observada em 184 casos (88,5%), a do VEGF em 131 (63%) e a do PDGF-C em 160 (77%). As DMVs medianas pelo CD34, PDGF-C, VEGF e CD105 foram, respectivamente, 20, 16, 5 e 6. Os GBMs com marcação positiva pelo HIF-1 tiveram uma DMV mediana pelo CD34 de 30, enquanto que nos negativos a DMV mediana foi 14 (p<0,001). A expressão tumoral positiva pelo HIF-1 teve correlação com a marcação tumoral pelo VEGF e PDGF-C (p<0,001). Houve também uma correlação entre a marcação do VEGF e do PDGF-C tanto no tumor (p=0,001) como na célula endotelial (p<0,001). A expressão do VEGF no tumor teve correlação com a sua expressão no vaso (p<0,001). Células endoteliais marcadas pelo PDGF-C e pelo VEGF também foram marcadas pelo CD105 e seus núcleos pelo KI-67 confirmando seu padrão neoangiogênico e proliferativo. A marcação nuclear das células tumorais pelo VEGF teve impacto na sobrevida (p=0,002), bem como as marcações nucleares pelo HIF-1 e VEGF (p=0,005). Em conclusão, este estudo mostrou que a expressão do HIF-1 está associada com as expressões do VEGF e do PDGF-C e que houve uma correlação desses marcadores com a angiogênese no GBM. / Glioblastoma multiforme (GBM) is the most aggressive tumour of the central nervous system (CNS) and is characterized by a high angiogenic power that is directly related to the invasiveness and inversely to the prognosis. Angiogenesis contributes to malignancy by providing the necessary oxygenation and nutritional supplement for the tumour\'s growth and invasion. GBM proliferates under a hypoxia environment and the hypoxia-inducible factor (HIF-1) plays a key role on the transcription of essential genes which promote angiogenesis and prevent cellular death. The vascular endothelial growth factor (VEGF) and the platelet-derived growth factor C (PDGF-C) are agents of great interest on tumour angiogenesis and may be modulated by the HIF-1. Tissue micro-array (TMA) was conducted on 208 cases of GBM and the HIF-1, VEGF and PDGF-C markers were studied under immunohistochemistry method. The results were correlated with angiogenesis assessed by micro-vessel density (MVD) for CD34, CD105, VEGF and PDGF-C, with endothelial cell proliferation by nuclear staining for KI-67, and also with survival. The tumour expression by HIF-1 was observed in 184 cases (88.5%), by VEGF in 131 (63%) and by PDGF-C in 160 (77%). The median MVD for CD34, PDGF-C, VEGF and CD105 was respectively 20, 16, 5 and 6.The GBMs which stained positive for HIF-1 showed a median MVD of 30 for CD34, whereas in negative ones, median MVD was 14 (p <0.001). The positive tumour expression for HIF-1 was correlated with tumour markings for VEGF and PDGF-C (p <0.001). There was also a correlation between the markings for VEGF and PDGF-C in both the tumour (p = 0.001) and endothelial cell (p <0.001). VEGF expression in the tumour was correlated with its expression in the blood vessel (p <0.001). Endothelial cells marked for the PDGF-C and VEGF were also marked for CD105 and their nuclei for KI-67 confirming its neoangiogenic and proliferative pattern. The nuclear staining on tumour cells for VEGF had an impact on survival (p = 0.002), as well as the cases with nuclear staining for HIF-1 and VEGF (p = 0.005). In conclusion, this study showed that HIF-1 expression is associated with VEGF and PDGF-C and correlated with angiogenesis on GBM.
378

Caracterização do perfil de microRNAs e genes alvo muscular esquelético envolvidos na rarefação microvascular de ratos espontaneamente hipertensos: papel do treinamento físico / MicroRNA profiles and their target genes involved in skeletal muscle microvascular rarefaction of spontaneously hypertensive rats

Fernandes, Tiago 07 August 2015 (has links)
A hipertensão arterial (HA) é uma síndrome multifatorial caracterizada por níveis elevados e sustentados de pressão arterial (PA). O treinamento físico (TF) aeróbio tem sido utilizado como um importante tratamento não farmacológico da HA, uma vez que ele corrige a rarefação microvascular e o perfil de fibras muscular e reduz a PA; entretanto, os mecanismos envolvidos são pouco conhecidos. Uma nova classe de pequenos RNAs, denominados de microRNAs (miRNAs), vem sendo muito estudados por regularem pós-transcricionalmente a expressão de seus genes alvo. Estudos avaliando o papel dos miRNAs na regulação do processo angiogênico e trofismo muscular tanto na HA quanto induzidos pelo TF são desconhecidos. Portanto, nosso objetivo é caracterizar o perfil de miRNAs e genes alvo do músculo esquelético envolvidos nos processos de rarefação microvascular e dano muscular na HA e verificar o papel terapêutico do TF de natação na correção desses parâmetros. Na primeira etapa do projeto, ratos espontaneamente hipertensos (SHR) com 3 meses de idade (HA recém estabelecida) e seus controles Wistar Kyoto (WKY) foram divididos em 4 grupos: SHR, SHR treinado (SHR-T), WKY e WKY treinando (WKY-T). O TF promoveu redução da PA em SHR e bradicardia de repouso acompanhando por um aumento VO2 nos animais treinados. O TF corrigiu a mudança na distribuição dos tipos de fibra muscular em SHR paralelamente a correção na expressão do miRNA-208b. A rarefação capilar foi prevenida em animais SHR-T concomitante a correção na expressão dos miRNAs-16, -21 e -126 envolvidos na promoção das vias angiogênicas e desativação de vias apoptóticas por alvejarem VEGF, Bcl-2 e PI3KR2. Na segunda etapa do projeto, SHR com 6 meses de idade (HA crônica) e seus controles WKY foram divididos nos mesmos 4 grupos da primeira etapa. Similares resultados foram observados nas respostas hemodinâmicas, mudança no perfil de fibras muscular e rarefação capilar. Em contraste, foi observado uma redução do VO2 acompanhado por uma atrofia e disfunção muscular em SHR. Além disso, estes animais apresentavam disfunção cardíaca e aumento na relação parede-lúmen da artéria femoral e arteríola muscular. O TF corrigiu estas alterações no vaso e no músculo. Curiosamente, o microarray de miRNAs muscular revelou um perfil de miRNAs envolvidos no remodelamento microvascular e muscular esquelético (miRNAs-96, -205, -182, -140, -328a, -665, -1, -499, -208b e -99b) possibilitando identificar genes alvo modificados pela HA e TF. Assim, alvos envolvidos na mudança do perfil de fibras, síntese protéica via IGF-I/ Akt/ mTOR e da via de sinalização angiogênica dependente e independente de VEGF foram prejudicadas na HA e corrigidos pelo TF. Juntos, os resultados apoiam a hipótese de que as alterações estruturais e funcionais advindas da progressão da HA possa ser regulada por um conjunto de miRNAs e genes alvo; e que o TF participa no restabelecimento muscular e da rede microvascular. Assim, há perspectiva do potencial terapêutico do uso de miRNAs no tratamento da HA / Hypertension is a multifactorial syndrome characterized by sustained high levels of blood pressure (BP). Aerobic exercise training (ET) has been used as an important non-pharmacological treatment of hypertension, since it corrects microvascular rarefaction, muscle fiber type profile and reduces BP; however, the mechanisms involved are poorly understood. A new class of small RNAs, called microRNAs (miRNAs), has been extensively studied because they regulate their target gene expression at the post-transcriptional level. Studies evaluating the role of miRNAs in the angiogenic process and muscle trophism both in hypertension and exercise training are unknown. Therefore, our goal is to characterize the skeletal muscle miRNA profiles and their target genes involved in microvascular rarefaction and muscle damage in hypertension and check the therapeutic role of swimming ET in correcting these parameters. In the first stage of the project, spontaneously hypertensive rats (SHR) aged 3 months (hypertension newly established) and their controls Wistar Kyoto (WKY) were divided into 4 groups: SHR, trained SHR (SHR-T), WKY and WKY training (WKY-T). ET promoted reduction in BP in SHR and resting bradycardia with subsequent increase in VO2in trained animals. ET corrected the change in proportion of muscle fiber types in SHR parallel with the correction in miRNA-208b expression. Capillary rarefaction was prevented in SHR-T group concomitant with the correction in the expression of miRNAs-16, -21 and -126 involved in promoting angiogenesis and deactivation of apoptotic pathways by targeting VEGF, Bcl-2 and PI3KR2. In the second stage of the project, 6-month-old SHR (chronic hypertension) and their controls WKY were divided into the same four groups as those in the first stage. Similar results were observed in hemodynamic responses, muscle fiber profile and capillary rarefaction. In contrast, we observed a reduction in VO2 accompanied by muscle atrophy and dysfunction in SHR. Moreover, these animals showed cardiac dysfunction and an increase in wall:lumen ratio of the femoral artery and muscle arteriole. ET corrected these changes in the vessel and muscle. Interestingly, the muscle miRNA microarray revealed a profile of miRNAs involved in microvascular and muscle remodeling (miRNAs-96, -205, -182, -140, - 328a, -665, -1, -499, -208b and -99b) making it possible to identify target genes modified by hypertension and ET. Thus, targets involved in changing the fiber profile, protein synthesis by the IGF-I/ Akt /mTOR pathway, and the VEGF-dependent and independent angiogenic signaling pathway, were impaired in hypertension and corrected by ET. Together, these results support the hypothesis that the structural and functional changes arising from the progression of hypertension may be regulated by a set of miRNAs and target genes; and ET participates in restoring the muscle and microvascular network. Thus, there are perspectives for the potential therapeutic use of miRNAs in the treatment of hypertension
379

Estudo comparativo de radiofármacos para angiogênese na detecção de melanoma / Comparative study of angiogenesis radiopharmaceuticals for melanoma detection

Oliveira, Érica Aparecida de 20 September 2011 (has links)
Diagnóstico precoce e tratamento de melanoma, um tumor cutâneo com o pior prognóstico, é extremamente importante para um resultado clínico favorável. A biblioteca de peptídeos phage display é um recurso útil de triagem para identificar peptídeos bioativos que interagem com alvos em cânceres. O objetivo desse estudo foi a avaliação de dois traçadores de tecnécio-99m com sequências peptídicas RGD e NGR, conjugados com o quelante bifuncional MAG3. Os conjugados peptídicos (10 &mu;L de uma solução &mu;g/&mu;L) foram marcados com tecnécio-99m usando tampão de tartarato de sódio. A avaliação radioquímica foi feita por ITLC e confirmada por CLAE. O coeficiente de partição foi determinado e ensaios de internalização foram realizados em duas linhagens celulares de melanoma (B16F10 e SKMEL28). A avaliação da biodistribuição dos traçadores foi realizada em animais sadios em diferentes tempos e também em camundongos portadores de células tumorais aos 120 min após a sua administração. Estudos de bloqueamento também foram conduzidos pela co-injeção de peptídeo frio. O desempenho dos conjugados peptídicos mostraram-se bastante parecidos em diversas avaliações. Eles foram radiomarcados com alta pureza radioquímica (>97%). Ambos são hidrofílicos, com excreção renal preferencial. A captação tumoral foi maior para células SKMEL28 do que para as células B16F10, especialmente para o 99mTc-MAG3-PEG8-c(RGDyK) (7,85±2,34 %DI/g) aos 120 min pós-injeção. O desempenho do 99mTc-MAG3-PEG8-c(RGDyk) foi superior que o do traçador com NGR, quanto à captação no melanoma humano podendo ser considerado como um promissor radiofármaco para diagnóstico de melanoma. / Early diagnosis and treatment of melanoma, a cutaneous tumor with a serious prognosis, is extremely important for optimal clinical outcome. Phage display peptide libraries are a useful screening resource for identifying bioactive peptides that interact with cancer targets. The aim of this study was the evaluation of two technetium-99m tracers for angiogenesis detection in melanoma model, using cyclic peguilated pentapeptide with RGD and NGR motifs conjugated with bifunctional chelator MAG3. The conjugated peptides (10 &mu;L of a &mu;g/&mu;L solution) were labeled with technetium-99m using a sodium tartrate buffer. Radiochemical evaluation was done by ITLC and confirmed by HPLC. Partition coefficient was determined and internalization assays were performed in two melanoma cells (B16F10 and SKMEL28). Biodistribution evaluation of the tracers was done in healthy animals at different times and also in mice bearing the tumor cells at 120 min post injection. Blocking studies were also conducted by co-injection of cold peptides. The conjugated showed the same profile in many evaluations. They were radiolabeled with high radiochemical purity (>97%). Both were hydrophilic, with preferential renal excretion. Tumor uptake was higher for human melanoma cells than for murinic melanoma cells, specially for 99mTc-MAG3-PEG8-c(RGDyK) (7.85±2.34 %ID/g) at 120 min post injection. The performance of 99mTc-MAG3-PEG8-c(RGDyk) was much better than NGR tracer concerning human melanoma uptake and might be considered in future investigations focusing radiotracers for melanoma diagnosis.
380

Expressão e caracterização das quimases recombinantes específicas de mastócitos de camundongos (mMCP4 e 5) / Expression and characterization of recombinant mouse mast cell chymases (mMCP4 e 5)

Santana, Ana Carolina 31 October 2014 (has links)
Os mastócitos, em associação com outras células inflamatórias se acumulam em locais de tumor. Entretanto, pouco é conhecido sobre o papel exato dos mastócitos e de seus mediadores na progressão tumoral e angiogênese. Resultados recentes do nosso laboratório mostraram que a expressão das triptases específicas de mastócitos está correlacionada com a progressão tumoral (de Souza, Jr, PLosOne 7(7): e40790). Além do mais, existe uma associação entre mastócitos e a angiogênese tumoral. Então, tornou-se interessante investigar o papel das quimases específicas de mastócitos (mMCP-4 e -5) neste processo. Visto que estas quimases não são disponíveis comercialmente, a primeira etapa deste estudo foi produzir as quimases mMCP-4 e -5 recombinantes. Assim, as sequências dos genes respectivos para mMCP-4 e -5, além das sequências para seis resíduos de His e do sítio suscetível a enteroquinase foram clonadas no vetor de expressão pPIC9. A cepa GS115 de Pichia pastoris foi transformada com o respectivo vetor para mMCP-4 ou -5. Os clones transformados foram crescidos em meio BMMY e induzidos com várias concentrações de metanol para a produção de mMCP-4 ou -5 recombinantes. Depois de 96 horas, o meio foi centrifugado e as quimases mMCP-4 ou -5 foram purificadas do sobrenadante usando resina de níquel. A identidade das proteínas foi confirmada por Western Blotting usando o anticorpo anti-his, assim como os anticorpos anti-mMCP-4 e -5. As proteases foram ativadas pela clivagem do sítio suscetível a enteroquinase por cinco horas, a 22°C. A ativação das enzimas foi confirmada através da degradação de seus substratos específicos. Estes resultados mostram que P. pastoris é um organismo eficiente para a expressão de ambas as proteases. Estas proteases recombinantes se constituem em ferramentas importantes para se elucidar o papel da mMCP-4 ou -5 na angiogênese. / Mast cells, in association with other inflammatory cells, are known to accumulate at tumor sites. However, little is known about the exact role that mast cells and their mediators play in tumor progression and angiogenesis. Recent results from our laboratory have shown that expression of mast cell specific tryptases correlates with tumor progression (de Souza, Jr, PLosOne 7(7): e40790). Furthermore, there is an association between mast cells and tumor angiogenesis. It then became of interest to investigate the role of mast cell specific chymases (mMCP-4 and -5) in this process. Since these chymases are not commercially available, the first step in this study was to produce recombinant mMCP-4 and -5. The gene sequences for these chymases along with the sequence for six His residues and an enterokinase susceptible peptide were cloned into the expression vector pPIC9. The GS115 strain of Pichia pastoris was transformed with the respective vector for either rmMCP-4 or -5. The transformed clones were grown in BMMY media and induced to produce rmMCP-4 or -5 with various concentrations of methanol. After 96 hours, the medium was centrifuged and rmMCP-4 or -5 was purified from the supernatant using nickel-nitrilotriacetic acid agarose beads. The identity of the proteins was confirmed by Western blotting using an anti-his antibody as well as anti-mMCP-4 and -5. These results show that P. pastoris is an efficient organism in which to express both proteases.

Page generated in 0.0548 seconds