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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
541

Atividade leishmanicida de derivados de quinolinas: 4-aminoquinolinas complexadas a esteroide e amodiaquina

Antinarelli, Luciana Maria Ribeiro 28 February 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-21T15:25:14Z No. of bitstreams: 1 lucianamariaribeiroantinarelli.pdf: 3736513 bytes, checksum: 7a35a693236ba9e982e630b172b6f3cf (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T19:10:52Z (GMT) No. of bitstreams: 1 lucianamariaribeiroantinarelli.pdf: 3736513 bytes, checksum: 7a35a693236ba9e982e630b172b6f3cf (MD5) / Made available in DSpace on 2017-08-07T19:10:52Z (GMT). No. of bitstreams: 1 lucianamariaribeiroantinarelli.pdf: 3736513 bytes, checksum: 7a35a693236ba9e982e630b172b6f3cf (MD5) Previous issue date: 2013-02-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A quimioterapia atual para as leishmanioses está longe do ideal devido a uma série de problemas como alto custo e elevada toxicidade. Assim, existe uma necessidade imediata de obtenção de novos fármacos para o tratamento da doença. Neste contexto, derivados de quinolina têm demonstrado atividade leishmanicida promissora. Neste trabalho, foi avaliada a atividade leishmanicida de duas séries distintas de quinolinas: seis compostos derivados de 4-aminoquinolinas (4-AMQ) e seus híbridos com esteroide e nove derivados da amodiaquina (AQ). O efeito dos compostos foi testado em promastigotas e amastigotas de Leishmania sp e em macrófagos peritoneais de camundongos. Os resultados mostraram que a conjugação de 4-AMQ ao esteroide resultou em aumento significativo da atividade principalmente para formas promastigotas e amastigotas de L. major. O composto 6 foi o mais ativo em amastigota de L. major (CI50 de 1,9 µM), sendo três vezes mais efetivo do que a miltefosina. Demonstrou-se neste trabalho que a conjugação de dois grupos de grande aplicação biológica, quinolina e esteroide, pode ser uma estratégia interessante para o desenvolvimento racional de novos fármacos. Em relação aos derivados da AQ, observou-se que a grande maioria dos compostos foram ativos em promastigotas e amastigotas de Leishmania sp. Dentre os nove compostos avaliados, seis foram mais ativos em amastigotas de L. braziliensis do que o protótipo AQ e miltefosina. O composto 8 (CI50 de 0,4 µM) foi cerca de quatorze vezes mais ativo em amastigota do que a miltefosina. A maioria dos derivados de 4-AMQ e AQ foram mais seletivos e específicos para amastigotas. A atividade em potencial dos compostos avaliados pode ser considerada um importante avanço no estudo desta classe de derivados, visando-se o desenvolvimento de novos fármacos leishmanicidas mais eficazes, seletivos e não tóxicos para o hospedeiro humano. / Current chemotherapy for leishmaniasis is far from ideal due to a number of problems such as high cost and high toxicity. Thus, there is an immediate need to obtain new drugs for the treatment the disease. In this context, quinoline derivatives have shown promising antileishmanial activity. In this study, we evaluated the activity of two distinct series of quinolines, six 4-aminoquinolines (4-AMQ) derivatives and their hybrids with steroid and nine amodiaquine (AQ) derivatives in different Leishmania species. Effect of the compounds was assayed against Leishmania promastigotes and amastigotes and mouse peritoneal macrophages. Results showed that the combination of 4-AMQ to the steroid resulted in a significant increase in activity mainly for L. major promastigotes and amastigotes forms. Compound 6 was the most active against L. major amastigotes with IC50 of 1.9 µM, being three times more effective than miltefosine. It was demonstrated in this work that the combination of two groups with large biological application as quinoline derivatives and steroids may be an interesting strategy for the rational development of new drugs. Regarding to the AQ derivatives, it was observed that all compounds were most active against Leishmania promastigote and amastigote forms. Among the nine compounds evaluated, six were more active against L. braziliensis amastigotes than the prototype AQ and miltefosine. Compound 8 with IC50 of 0.4 µM was about fourteen times more active than miltefosine. In general, the majority of 4-AMQ and AQ derivatives are more selective and specific for amastigotes of Leishmania sp, forms clinically relevant. Potential activity of the compounds evaluated can be considered an important advance in the study of this class of derivatives in order to develop new leishmanicidal drugs more effective, selective and nontoxic to the human host.
542

TLR4 em células derivadas da medula óssea é um mediador da resistência à insulina associada à obesidade / TLR4 in bone marrow-derived cells is a mediator of obesity-related insulin resistance

Razolli, Daniela Soares, 1984- 25 August 2018 (has links)
Orientador: Licio Augusto Velloso / Texto em português e inglês / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-25T09:35:56Z (GMT). No. of bitstreams: 1 Razolli_DanielaSoares_D.pdf: 6783117 bytes, checksum: a457ef1952b61a9b35b688c018c62b0a (MD5) Previous issue date: 2014 / Resumo: A ativação de TLR4 por ácidos graxos saturados presentes na dieta é um dos mais importantes mecanismos envolvidos no desenvolvimento da resistência à insulina. Entretanto, não está claro se este efeito decorre da ativação de TLR4 em células derivadas da medula óssea, em células de tecidos insulino-sensíveis, ou em ambos. O objetivo de nosso estudo foi investigar se a ausência ou presença de TLR4 exclusivamente em células derivadas da medula óssea (BM) é suficiente para modular a ação da insulina no fígado e no tecido adiposo de camundongos com obesidade induzida por dieta. Camundongos mutantes (TLR4-/-) ou selvagens (WT) para TLR4 foram irradiados em fonte de cobalto 60 e submetidos ao transplante de medula óssea (BMT). TLR4-/- receberam medula óssea de camundongos WT e vice-versa. Após a recuperação, os animais foram alimentados com dieta rica em gordura saturada ou dieta padrão para roedores por oito semanas. Foram avaliados ganho de peso, ingestão alimentar, gasto energético e marcadores de termogênese no tecido adiposo marrom (BAT). A sensibilidade à insulina foi analisada por ITT e pela fosforilação de AKT no fígado e tecido adiposo. O metabolismo de glicose foi avaliado por GTT e pela expressão relativa de PEPCK e G6PASE no fígado. Ainda, marcadores de inflamação foram avaliados no fígado e tecido adiposo por PCR em tempo real, e o acúmulo de gordura hepática foi analisado pela marcação por OilRed. Nossos resultados revelaram que em camundongos WT recebendo BM de doadores TLR4-/- ocorreu proteção contra o desenvolvimento de obesidade e resistência à insulina induzida por dieta. Em camundongos TLR4-/- recebendo BM de doadores WT houve perda da proteção contra a obesidade e resistência à insulina induzida por dieta. A transferência de fenótipo relativo a massa corporal foi acompanhada de modificação na eficiência energética e na expressão de UCP1 em tecido adiposo marrom. A transferência de fenótipo relativo a resistência à insulina foi acompanhado da modificação do padrão de ativação de transdução do sinal da insulina por meio de AKT em fígado e tecido adiposo. Particularmente no fígado, a presença de TLR4 funcional em células derivadas da BM foi fator determinante no desenvolvimento da esteatose. Por fim, a presença de TLR4 funcional em células derivadas da BM foi acompanhada da expressão de níveis elevados de citocinas pró-inflamatórias e nível reduzido de pelo menos uma citocina anti-inflamatória em fígado e tecido adiposo, sendo que a ausência de TLR4 nas células derivadas da BM resultou em fenótipo inverso. Desta forma, conclui-se que a presença ou ausência de TLR4 em células derivadas da BM tem papel determinante, sendo simultaneamente necessário e suficiente para o desenvolvimento do fenótipo de obesidade e resistência à insulina induzida por dieta / Abstract: Saturated fatty acid-induced activation of TLR4 is one of the most important mechanisms involved in the development of insulin resistance. However, it is not clear if this effect is due to activation of TLR4 present in bone marrow (BM)-derived cells, in cells present in tissues that are targets for insulin action, or in both. The aim of the present study was to investigate if a defective TLR4 signaling in bone-marrow (BM) derived cells is sufficient to modulate the whole-body insulin action. TLR4-mutant (TLR4-/-) and wild-type (WT) mice were irradiated in a cobalt 60 source and submitted to bone marrow transplantation (BMT). TLR4-/- received BM from WT and vice-versa. After recovery, mice were fed on a high fat diet (HFD) or standard chow for eight weeks. We evaluated body mass gain, food intake, energy expenditure and markers of thermogenesis in brown adipose tissue (BAT). Insulin sensitivity was analyzed by GTT, ITT and AKT phosphorylation in liver and adipose tissue. In addition, markers of inflammation were evaluated in both tissues by real-time PCR. WT submitted to BMT from TLR4-/- donors were protected from HFD-induced obesity and insulin resistance. In TLR4-/- submitted to BMT from WT donors this effect was blunted and mice gained weight and became insulin resistant. Phenotype transfer regarding body mass was accompanied by change in energy efficiency and expression of UCP1 in brown adipose tissue. Phenotype transfer regarding insulin resistance was accompanied by changes in insulin signal transduction through AKT in liver and adipose tissue. Particularly, in the liver, the presence of a functional TLR4 in BM-derived cells was a determinant factor for the development of steatosis. Finally, the presence of a functional TLR4 in BM-derived cells was accompanied by the increased expression of inflammatory cytokines and reduced expression of at least one anti-inflammatory cytokine in the liver and adipose tissue. Thus, we conclude that the presence or absence of TLR4 in BM-derived cells is both sufficient and necessary for the induction of obesity and insulin resistance induced by diet / Doutorado / Fisiopatologia Médica / Doutora em Ciências
543

Associação do Epstein-Barr vírus com os anticorpos anti-CCP, os alelos do epítopo compartilhado e o tabagismo em pacientes brasileiros com artrite reumatoide / Association of Epstein-Barr virus with anti-CCP antibodies, the shared epitope alleles and smoking in Brazilian patients with rheumatoid arthritis

Yazbek, Michel Alexandre, 1978- 09 May 2014 (has links)
Orientadores: Manoel Barros Bértolo, Lilian Tereza Lavras Costallat / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T07:51:21Z (GMT). No. of bitstreams: 1 Yazbek_MichelAlexandre_D.pdf: 3193834 bytes, checksum: 4155cea9577385c29405700add4864ef (MD5) Previous issue date: 2014 / Resumo: A etiopatogenia da Artrite Reumatoide (AR) envolve fatores genéticos, imunológicos e ambientais que interagem entre si. Os principais fatores de risco estudados são a presença dos alelos do epítopo compartilhado (shared epitope- SE), dos anticorpos anti-peptídeos cíclicos citrulinados (anti-CCP) e do tabagismo. Há evidências que o Epstein-Barr vírus (EBV), ao interagir com esses fatores de risco, possa causar uma resposta imune anômala em indivíduos susceptíveis. Essas interações também podem contribuir para o desenvolvimento da AR. O objetivo principal desse estudo é estabelecer se há uma associação entre o EBV com os alelos do SE, os anticorpos anti-CCP e o tabagismo em pacientes brasileiros com AR. Os objetivos secundários são: avaliar a correlação entre os alelos do SE, os anticorpos anti-CCP e o tabagismo; detectar a exposição ao EBV e quantificar sua carga viral e estimar o risco de cada fator estudado para o desenvolvimento da AR nessa casuística. Nesse estudo caso-controle, incluímos 140 pacientes brasileiros com AR e 143 controles saudáveis; pareados por idade, sexo e etnia. Foi feita uma caracterização clínico-laboratorial da casuística. Foram realizadas a genotipagem para identificar os alelos do SE, a determinação dos anticorpos anti-CCP pelo método de ELISA e coletada a história de tabagismo de todos os sujeitos da pesquisa. Para avaliar a exposição ao EBV, realizamos a dosagem dos anticorpos anti-Epstein-Barr Nuclear Antigen 1 (anti-EBNA1). Para quantificar a carga viral do EBV, realizamos o método quantitativo da reação em cadeia polimerase em tempo real ou real-time PCR. A análise comparativa entre os grupos mostrou uma positividade significativamente maior para os alelos do SE, anticorpos anti-CCP e tabagismo no grupo de pacientes. A análise dos anticorpos anti-EBNA1 mostrou uma positividade alta, tanto em pacientes como em controles, sem diferença significativa. Entretanto, a quantificação da carga viral pela PCR em tempo real mostrou-se muito maior em pacientes do que em controles (p<0.001). As análises associativas dos anticorpos anti-EBNA1 com os outros fatores estudados não se mostraram significativas; assim como as análises associativas da carga viral do EBV pela PCR em tempo real. A positividade do anti-CCP foi maior em pacientes com os alelos do SE que são tabagistas ou ex-tabagistas (p=0.038). Nas análises de regressão logística, a variável com maior risco para o desenvolvimento da AR foi a positividade dos anticorpos anti-CCP. Apesar dos pacientes com AR apresentarem uma carga viral do EBV aumentada, esse estudo não conseguiu associá-la aos demais fatores de risco estudados. Sugerimos que esses achados possam ocorrer devido a um controle deficitário do EBV em pacientes com AR, mas que não está relacionado aos fatores de risco mais conhecidos da doença. A imunidade celular defeituosa dos pacientes com AR dificulta o controle de uma infecção latente do vírus. Portanto, não é possível estabelecer uma relação causal direta entre o EBV e a AR / Abstract: The pathogenesis of rheumatoid arthritis (RA) involves genetic, immunological and environmental factors. The main risk factors are the presence of the shared epitope alleles (shared epitope- SE), anti-cyclic citrullinated peptide antibodies (Anti-CCP) and smoking. There is evidence that the Epstein-Barr virus (EBV), when interacts with these risk factors, may cause an abnormal immune response in susceptible individuals. These interactions may contribute to the development of RA. The main objective of this study is to establish whether there is an association between EBV and alleles of SE, anti-CCP antibodies and smoking in Brazilian patients with RA. Secondary objectives are the assessment of the correlation between alleles of SE, anti-CCP antibodies and smoking; the detection of EBV; the quantification of EBV viral load and the estimation of the likelihood of each analyzed factor for the development of RA in this sample. In this case-control study, we included 140 Brazilian patients with RA and 143 healthy controls; matched for age, sex and ethnicity. We performed a clinical and laboratory characterization of the sample. Genotyping was performed to identify SE alleles, anti-CCP antibodies were examined by ELISA and smoking information was collected from all subjects. To assess the exposure to EBV, we examined anti-Epstein-Barr Nuclear Antigen 1 (anti-EBNA1) antibodies. To quantify the viral load of EBV, we performed the quantitative method of polymerase chain reaction in real time or real-time PCR. The comparative analysis between groups showed a significantly higher positivity for the alleles of SE, anti-CCP antibodies and smoking in patients. The analysis of anti-EBNA1 antibodies showed a high positivity, both in patients and in controls, with no significant difference. However, the quantification of viral load by real-time PCR proved to be much higher in patients than in controls (p <0.001). Associative analysis of anti-EBNA1 antibodies with other factors studied were not significant; as well as the association analyzes of the EBV viral load by PCR in real time. The positivity of anti-CCP antibodies was higher in patients with SE alleles which are smoker or ex-smoker (p = 0.038). In logistic regression analyzes, the variable with higher risk for RA was the positivity of anti-CCP antibodies. Although patients with RA present an increased EBV viral load, this study did not link EBV to the other risk factors studied. We suggest that these findings may be due to a deficient control of EBV in RA patients, which is unrelated to the better-known disease risk factors. Defective cellular immunity of patients with RA complicates the control of latent virus infection. Therefore it is not possible to establish a direct causal relationship between EBV and RA / Doutorado / Clinica Medica / Doutor em Clínica Médica
544

Metalopolímero de pentacianoferrato e poli(4-vinilpiridina) : síntese, caracterização e aplicação na produção de estruturas automontadas / Pentacyanoferrate and poly(4-vinylpyridine) metallopolymer : synthesis, characterization and application to the production of self-assembled structures

Jannuzzi, Sergio Augusto Venturinelli, 1987- 12 February 2011 (has links)
Orientadores: André Luiz Barboza Formiga, Maria Isabel Felisberti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-20T16:07:14Z (GMT). No. of bitstreams: 1 Jannuzzi_SergioAugustoVenturinelli_M.pdf: 35610656 bytes, checksum: f2dffeb8cf285399ac0996a04b2601a7 (MD5) Previous issue date: 2011 / Resumo: O presente trabalho ocupa-se da síntese, caracterização e aplicação de um material híbrido orgânico-inorgânico em que o bloco orgânico é o polímero poli(4-vinilpiridina) e o bloco inorgânico é o pentacianoferrato(II) de sódio. A primeira parte trata da influência do polímero nas propriedades do complexo, e vice-versa. A segunda parte ilustra a aplicação do metalopolímero na produção de estruturas análogas ao azul da Prússia (AP) pela reação de Fe com as unidades pentacianoferrato. A banda de transferência de carga metal-ligante do pentacianoferrato do metalopolímero em solução desloca-se para energias menores na medida em que aumenta a fração de meros livres da cadeia polimérica, indicando que a fração do bloco orgânico modula a polaridade do ambiente químico do complexo. Por outro lado, a crescente quantidade de complexo ligado às cadeias poliméricas aumenta viscosidade das soluções de metalopolímeros, evidenciando que o pentacianoferrato expande o novelo macromolecular. Estruturas tipo azul da Prússia sintetizadas a partir do metalopolímero exibem elevada estabilidade coloidal quando comparadas aos compostos isentos de polímero e apresentam banda de intervalência em menores energias do que o frequentemente reportado para esse tipo de estrutura, provavelmente em virtude do envolvimento das partículas de AP pelo polímero / Abstract: This work comprises the synthesis, characterization and application of a hybrid organic-inorganic metallopolymer, in which the organic block is the polymer poly(4-vinylpyridine) and the inorganic block is the complex sodium pentacyanoferrate(II). The first part presents the influence of the polymer on the properties of the complex and vice-versa. The second part illustrates an application of the metallopolymer on the production of Prussian blue (AP) analogs based on the reaction of Fe with the pentacyanoferrate moieties. The metal-to-ligand charge transfer band of the polymer-bound pentacyanoferrate in solution shifts towards lower energies whereas the free monomers fraction arises. It indicates that the organic block fraction tunes the polarity of the pentacyanoferrate chemical environment. On the other side, the increasing fraction of complex bound to the polymer chain increases the metallopolymer solution viscosities. This is an evidence that the pentacyanoferrate expands the macromolecular coil. Prussian blue-type structures synthesized from metallopolymers exhibit enhanced colloidal stability when compared to the polymer-free compounds. They also present intervalence bands at lower energies than those frequentlly reported for this type of inorganic structure. The reason is probably the polymer wrapping of the particles / Mestrado / Quimica Inorganica / Mestre em Química
545

Extrato diclorometano de eugenia punicifolia: modulação do fenótipo colinérgico na retina de ratos neonatos in vitro

Cabo, Carolina Serra Jogaib 24 March 2017 (has links)
Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-03-24T17:09:38Z No. of bitstreams: 1 Cabo, Carolina Serra Jogaib [Dissertação, 2014].pdf: 1585469 bytes, checksum: c26025e0cb73856aeb3ee836ea718d62 (MD5) / Made available in DSpace on 2017-03-24T17:09:38Z (GMT). No. of bitstreams: 1 Cabo, Carolina Serra Jogaib [Dissertação, 2014].pdf: 1585469 bytes, checksum: c26025e0cb73856aeb3ee836ea718d62 (MD5) / Estudos sobre os efeitos do extrato aquoso da Eugenia punicifolia (EP) demonstram sua ação na neurotransmissão da junção neuromuscular. Entretanto, apesar de saber que o aumento da neurotransmissão colinérgica pode apresentar atividade neuroprotetora e atuar na plasticidade neuronal, não existem estudos sobre o efeito do extrato de EP em células do Sistema Nervoso Central. O objetivo deste trabalho foi estudar o efeito do extrato diclorometano de EP sobre células da retina de ratos neonatos in vitro no que tange à proliferação celular, modulação do fenótipo colinérgico e aos níveis de fator de crescimento do nervo (NGF), fator neurotrófico derivado do cérebro (BDNF) e da interleucina IL-4. Foram realizadas culturas primárias de células da retina de ratos neonatos da linhagem Lister Hooded de ambos os sexos, dia pós-natal 0-2. As culturas foram plaqueadas em placas de Petri pré-tratadas com poli-L-ornitina, na densidade de 1,0x105 cel/cm2, receberam meio 199 ou 1μg/mL do extrato diclorometano de Eugenia punicifolia (EP 1μg/mL) e foram mantidas por 48 horas a 37°C, em atmosfera de 95% de ar e 5% de CO2. O método bioquímico utilizado para análise da proliferação celular foi a incorporação de [3H]-timidina. Os níveis dos receptores muscarínicos, de neurotrofinas e citocinas foram determinados por Western Blot. Todos os dados são apresentados em relação à porcentagem do controle (100%). Os procedimentos experimentais foram aprovados pelo Comitê de Ética no Uso de Animais da UFF (Projeto nº 186/2012). Os resultados mostram que o tratamento das culturas com diferentes concentrações do extrato diclorometano de EP por 48h induziu aumento dependente da concentração na proliferação celular, sendo o aumento mais significativo observado na concentração de 1μg/mL, concentração que foi utilizada em todos os experimentos. Foi observada a redução nos níveis dos receptores muscarínicos M1 e M4, e nos níveis de transportador de acetilcolina associado à vesícula, aumento na expressão do receptor M3 e nenhuma alteração nos níveis do receptor M5. Observou-se, também, que o extrato diclorometano de EP aumenta os níveis de NGF e da interleucina-4, e diminui dos níveis de BDNF. Os resultados sugerem que o extrato diclorometano de EP exerce efeito proliferativo e de diferenciação através da alteração do fenótipo colinérgico da retina e da participação de fatores neurotróficos / Studies on the effects of the Eugenia punicifolia (EP) aqueous extract demonstrate its action on neurotransmission in the neuromuscular junction. However, despite knowing that increased cholinergic neurotransmission may have neuroprotective activity and act in neuronal plasticity, there are no studies on the effect of the extract of EP in cells of the Central Nervous System. The aim of this work was to study the effect of the dichloromethane extract of EP on retinal cells of neonatal rats in vitro with respect to cell proliferation, modulation of the cholinergic phenotype and levels of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and interleukin IL-4. Primary cell cultures of neonatal rat retina from Hooded Lister strain of both sexes, postnatal day 0-2 were performed. Cultures were plated on pre-treated Petri plates with poly-L- ornithine at a density of 1.0 x105 cel/cm2 received medium 199 or 1μg/mL of dichloromethane extract of E. punicifolia (EP 1μg/mL) and kept for 48 hours at 37°C in an atmosphere of 95% air and 5% CO2. The method used for biochemical analysis of cellular proliferation was the incorporation of [3H]-thymidine. The levels of muscarinic receptors, neurotrophins and cytokines were determined by Western blot. All data are presented in relation to the percentage of control (100%). The experimental procedures were approved by the Ethics Committee on Animal Use of UFF (Project nº 186/2012). The results show that treatment of cultures with different concentrations of the dichloromethane extract of EP for 48h induces an increase in cell proliferation, with the most significant increase observed with the concentration of 1μg/mL, concentration, which was used in all experiments. A reduction in levels of muscarinic receptors M1 and M4, and VAChT was observed, an increase in expression of the M3 receptor and no change in the levels of the M5 receptor were observed. Also was observed that the dichloromethane extract of EP increased NGF levels and interleukin-4, and decreases levels of BDNF. The results suggest that the dichloromethane extract of EP exerts a proliferative effect and differentiation by altering the cholinergic phenotype of the retina and the involvement of neurotrophic factors
546

Nanocristaux, films et cellules photovoltaïques de Cu2ZnSn(SSe)4 par impression d'encres / CZTSSe nanocrystals, liquid processed films and solar cells

Foncrose, Vincent 05 November 2015 (has links)
Cu2ZnSnSSe4 (CZTSSe) est un matériau prometteur comme absorbant de cellules photovoltaïques. Le développement à grande échelle de cellules solaires CZTSSe est conditionné au développement de procédés bas coût et soucieux de l'environnement. Dans ce contexte, le développement de films de CZTSSe à partir d'encres tout aqueuses de nanoparticules de CZTS constitue un challenge intéressant. Une stratégie haute température en présence d'un agent texturant gaz a été définie pour synthétiser des nanocristaux de CZTS présentant des surfaces polaires. Notre procédé agent texturant gaz met en œuvre la formation simultanée de nucléis de CZTS et de bulles de gaz. Nous montrons que la production en conditions de forte sursaturation d'une très forte concentration de nucléis de CZTS en association à un très grand nombre de petites bulles de gaz représente les conditions optimales de formation de nanocristaux. Par une étude électrocinétique, une condensation régulée par la taille de l'ion alcalin est observée dans la série des alcalins Li+ < Na+ < K+ < Rb+ < Cs+, démontrant la stabilité chimique des surfaces de Cu2ZnSnS4 en dispersion toute aqueuse. Par mise en œuvre des dispersions tout aqueuses, nous avons réalisé l'acquisition de données de base permettant de produire une preuve de concept de la formation d'un film sans fissures. Un autre point important à considérer lors de l'utilisation de matières premières bas coût est l'élimination des impuretés inhibitrices de la croissance des grains. Un profil spécifique de recuit des films est proposé mettant en œuvre une purification haute température pour l'élimination du carbone. En effet, notre stratégie met en œuvre la décomposition des domaines amorphes en carbone sp2 qui est ultérieurement éliminé via la formation de CSe2 gazeux. Finalement, des cellules solaires ont été fabriquées avec succès à partir d'encres tout aqueuses avec des rendements de conversion préliminaires jusqu'à 2,6 %. / Recently more attention is devoted to Cu2ZnSnS4 (CZTSSe) for photovoltaic applications due to their non-toxic, earth-abundant components and good optoelectronic properties. Large scale fabrication of CZTSSe solar cells will rely on the development of low-cost and environmentally-friendly approach. In this context, development of CZTSSe films from all-aqueous CZTS nanocrystals inks represents an interesting challenge. A high temperature, gas-templating strategy has been defined to synthesize highly crystallized CZTS nanocrystals displaying polar surfaces. Our gas-templating process involves the simultaneous formation of CZTS nucleis and gas bubbles. We demonstrate that production of a high rate of small gas bubbles, as well as a high concentration of nucleis, depict optimal conditions for nanocrystal synthesis. By an electrokinetic investigation, a condensation regulation by the alkali ion size is observed in the alkali series Li+ < Na+ < K+ < Rb+ < Cs+, demonstrating the chemical stability of CZTS surfaces in aqueous basic dispersions. By using all-aqueous chalcogenide nanocrystals dispersions, we determined a critical cracking thickness of 250 nm and an average thickness of 100 nm to fabricate micron crack-free films using a multilayer procedure. Having in mind these results, we give the proof of concept of crack-free film formation from all aqueous CZTS nanocrystals inks. Another important consideration, when employing low-cost materials, is the removal of impurities, inhibitors of grain growth. A specific annealing profile is proposed involving a high temperature purification step in order to remove carbon. Indeed, our strategy involves the decomposition of amorphous domains into sp2 carbon which will be further removed via the CSe2gas formation. Finally, CZTSSe solar cells are successfully fabricated from all-aqueous CZTS inks with preliminary devices efficiencies up of 2.6%.
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Synthèse et propriétés de nanoparticules d’or par chimie sous rayonnement utilisant des polysaccharides naturels comme agents stabilisants. / Synthesis and properties of gold nanoparticles by radiation chemistry using natural polysaccharides as stabilizers

Vo, Nguyen Dang Khoa 17 July 2013 (has links)
L'objectif est la mise au point d'une méthodologie de synthèse des nanoparticules d'or en présence du chitosane sous rayonnement permettant l'obtention d'objet de taille homogène et contrôlée. Dans ce but, nous mettrons l'accent sur l'étude des interactions entre les ions Au(III) et le chitosane en solution avant irradiation. En effet, la coordination entre des unités de glucosamine et l'ion Au(III) favorise la réduction de Au(III) en Au(0) et la formation de nanoparticules d'or. Cela est démontré clairement par l'étude de l'influence du pH sur la formation de nanoparticule lors du vieillissement des solutions d'HAuCl4 en présence de chitosane. Ce phénomène a été avance pour expliquer tout au moins partiellement, le mécanisme de la réduction des ions Au(III) en présence du chitosane sous rayonnement. Il s'agissait de définir si le mécanisme de réduction des ions Au(III) en ions Au(0) suivait un processus classique tels qu'il a été décrit dans les travaux de Belloni et de Henglein, ou si la présence de chitosane influe sur ce processus. L'élaboration des nanoparticules d'or en présence du chitosane utilisé comme agent stabilisant a été réalisée sous irradiation par faisceau d'électrons ou par rayonnement gamma. L'influence des paramètres de synthèse (rapport du [GLA]/[Au(III)], conditionnement des échantillons, effet de la dose d'irradiation, effet du débit de dose, rôle d'un piégeur de radicaux ou d'électrons solvatés) a ensuite été évaluée sur les propriétés caractéristiques des solutions de nanoparticules d'or (taille, charge, résonance plasmon de surface). L'activité catalytique des nanoparticules synthétisées a été testée vis-à-vis de la réaction de réduction du 4-nitrophénol en 4-aminophénol par NaBH4.Mots-clés : or, nanoparticules, chitosane, coordination, irradiation, faisceau d'électrons, rayonnement gamma, 4-nitrophénol. / The goal of this work is to develop a methodology for the synthesis of gold nanoparticles in the presence of chitosan under radiation to obtain a homogeneous object and controlled size. To reach this purpose, we will focus on the study of interactions between the ions Au(III) and chitosan in solution before irradiation. Indeed, the coordination between units of glucosamine and Au(III) promotes the reduction of Au(III) to Au(0) and the formation of gold nanoparticles. This is clearly demonstrated by the influence of pH on the formation of nanoparticles upon aging of HAuCl4 solutions in the presence of chitosan. This formulation has been used to explain the mechanism of reduction of Au(III) in the presence of chitosan in radiation. It was to define whether the reduction mechanism of ion Au(III) ions Au(0) followed a conventional process such as those described by the work of Belloni and Henglein, or if the presence of chitosan affects this process. The development of gold nanoparticles in the presence of chitosan used as a stabilizing agent was produced by the electron beam and gamma radiation. The influence of the synthesis parameters (report [GLA]/[Au (III)], sample conditioning, effect of irradiation dose, dose rate effect, role of a radical scavenger) on the characteristic gold nanoparticles was then evaluated (size, charge, surface plasmon resonance). The catalytic activity of these nanoparticles was tested towards the reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH4.Keywords: gold, nanoparticles, chitosan, coordination, irradiation, electron beam, gamma radiation, 4-nitrophenol.
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Modulation des fonctions des lymphocytes T CD8 par l'Interleukine-4 et les cytokines de la famille γc / Modulation of CD8 T lymphocytes functions by Interleukine-4 and γc cytokines

Ventre, Erwann 07 December 2011 (has links)
Les Lymphocytes T CD8 (LT CD8) sont des cellules du système immunitaire capables de reconnaître et de détruire des cellules infectées ou tumorales. De plus, les LT CD8 mémoires générés suite à une première rencontre avec un agent pathogène confèrent à l’organisme une protection efficace contre une réinfection. Cela a pour origine une modification des capacités effectrices et migratoires des LT CD8 mémoires par rapport aux LT CD8 naïfs. Ces fonctions améliorées des LT CD8 mémoires peuvent être régulées : des travaux préalables réalisés au sein de l’équipe ont montré que l’Interleukine-4 (IL-4), une cytokine sécrétée lors des réponses allergiques ou contre des pathogènes extracellulaires, inhibe certaines propriétés des cellules mémoires comme la sécrétion rapide de CCL5. Les effets de l’IL-4 sur les fonctions des LT CD8 mémoires sont cependant mal caractérisés : l’objectif de cette thèse a été de les identifier plus précisément. En utilisant une approche par micro-array, nous avons identifié une signature de gènes régulés par l’IL-4 dans les LT CD8 mémoires et montré que cette cytokine modifie l’expression de gènes impliqués dans la prolifération, la migration, et les fonctions effectrices des LT CD8 mémoires. Nous avons montré que l’IL-4 inhibe l’expression du récepteur de costimulation NKG2D à la surface des LT CD8 mémoires in vivo, s’accompagnant d’une diminution du signal costimulateur délivré par l’engagement de NKG2D. Nous avons également montré que la présence de certaines cytokines γc telles que l’IL-4 ou l’IL-21 lors de l’activation cellulaire affecte fortement les fonctions des LT CD8 effecteurs générés ainsi que leur différenciation en cellules mémoires. / Immunological memory is characterized by a secondary response that is faster and stronger than the primary response. For CD8 T cells this results from an increase frequency of antigen specific cells that display an improved response as compared to naïve cells. Memory CD8 T cells also display a new pattern of surface molecules that is associated with modified homing or activation properties. γc cytokines are known to affect both CD8 T cells functions and survival. Indeed, IL-4, a γc cytokine involved in Th2 responses induced in response to parasitic infections or allergies has been shown to reduce both IFNγ secretion and cytotoxicity of CD8 T lymphocytes. In the lab, we have demonstrated that IL-4 down-regulates ccl5 mRNA stores by inhibiting ccl5 transcription via a STAT6-dependent pathway. However, effects of IL-4 on CD8 T cells’ biology remain largely unknown. To identify such effects, we realised a microarray study that allowed us to identify the signature of genes affected by IL-4 in memory CD8 T cells. Among this signature, we identified genes involved in several functions of CD8 T cells, such as proliferation, migration, and effector functions. We then confirmed both in vitro and in vivo that NKG2D, a member of the NK receptors family involved in the modulation of the activation threshold of memory CD8 T cells, is down-regulated by IL-4, inhibiting NKG2D-dependant costimulation of memory CD8 T cells. Finally, we found that γc cytokines such as IL-4 and IL-21 affect the effector capacities of in vitro activated CD8 T Cells, as well as the differentiation of activated cells into memory cells.
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The Synthesis of N-(4-Nitrophenacyl)-4-Alkylpyridinium Halides and Reduction Products

Herd, Ray January 1950 (has links)
The synthesis of several N-(4-nitrophenacyl)-4-alkylpyridinium halides and their reduction products, 1-(4-aminophenyl)-2-[1-(4-alkylpiperidyl)]ethanols, was undertaken because of structural analogies between these and other physiologically active compounds, such as chloroamphenicol (I), 4,4'-diaminodiphenyl sulfone (II), and 2,2-bis(p-aminophenyl)-1,1,1-trichloroethane (III).
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A Study of the Reduction Products of N-(4-Nitrophenacyl)-4-(1-Hexyl)pyridinium Bromide

Arnwine, Bennie C. January 1950 (has links)
Because of the structural analogies between these compounds and several other physiologically active compounds, such as chloroamphenicol, 4,4'-diaminodiphenyl sulfone, and 2,2-bis-(p-aminophenyl)-1,1,1-trichloroethane, a more complete study of the reduction products and the sequence of catalytic reduction of N-(4-nitrophenacyl)-4-(1-hexyl)pyridinium bromide was made in this investigation.

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