• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 489
  • 217
  • 215
  • 60
  • 35
  • 32
  • 28
  • 25
  • 24
  • 18
  • 14
  • 13
  • 8
  • 5
  • 3
  • Tagged with
  • 1369
  • 156
  • 147
  • 124
  • 112
  • 110
  • 103
  • 102
  • 93
  • 91
  • 90
  • 86
  • 76
  • 75
  • 75
  • 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.
101

Réseau de contrôle de la traduction par l'Hormone Folliculo-Stimulante / Translational control network regulate by follicle-stimulating hormone

León Huamán, Kelly Blanca 18 December 2013 (has links)
La FSH est une hormone clé dans la fonction de reproduction. La compréhension de ces mécanismes moléculaires est essentielle pour comprendre ses effets biologiques. Nous montrons ici pour la première fois que non seulement la FSH induit le recrutement de polysomes dans la cellule de Sertoli, mais qu’en plus, elle stimule la traduction de deux ARNm sélectivement, c-fos et vegfa. La p70S6K est impliquée dans ce mécanisme. La FSH active et induit le recrutement de la p70S6K sur la coiffe des ARNm où elle active ses cibles traductionnelles. Les β-arrestines, des protéines d’échafaudage qui régulent la signalisation du RFSH, semblent participer à l’activation de la p70S6K. La déplétion des β-arrestines augmente massivement le recrutement de la p70S6K à la coiffe et diminue son activité enzymatique. De plus, la p70S6K et les β-arrestines interagissent mais cette interaction ne semble pas modulée par la FSH. Nos résultats suggèrent que les β-arrestines séquestreraient la p70S6K inactive pour permettre son activation et son recrutement à la coiffe m7GTP en réponse à la FSH. Ce travail apporte de nouvelles connaissances sur le rôle de la FSH dans la traduction et les mécanismes de signalisation impliqués. / FSH is a key hormone of the reproductive function. A clear understanding of its molecular mechanism is essential to fully understand its biological effects. Here, we show for the first time that FSH not only enhances the assembly of polysomes but also stimulates the translation of at least two mRNA selectively, c-fos and vegfa, in Sertoli cells. p70S6K participates in this mechanism. FSH activates and enhaced p70S6K recruitment to the m7GTP cap structure of mRNA where this kinase phosphorylates its targets. β-arrestins, which are scaffolding proteins that regulate FSH signalling, seem to participate in p70S6K activation. Accordingly, β-arrestins depletion increased p70S6K recruitment to the cap and reduced its enzymatic activity. Importantly, p70S6K and β-arrestins interact but the interaction is not FSH-dependent. We assume that β-arrestins sequester inactive p70S6K to activate it locally and then p70S6K translocates to the cap in response to FSH. In conclusion, this work brings new knowledge about FSH function in translational control and the signaling mechanisms involved.
102

Influência da suplementação de β-alanina associada ao treinamento intervalado de alta intensidade no desempenho de sprints repetidos / Influence of β-alanine supplementation associated with high-intensity interval training in the repeated sprints performance

Milioni, Fabio 20 August 2018 (has links)
Submitted by FABIO MILIONI (fmilioni@yahoo.com.br) on 2018-10-02T18:52:19Z No. of bitstreams: 1 Tese Doutorado Final.pdf: 5513111 bytes, checksum: 185eb55afcd55e67724ab68aa2e03ab4 (MD5) / Rejected by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: 1 - Favor inserir a ficha catalográfica no corpo do texto, pois é um item obrigatório. Agradecemos a compreensão on 2018-10-03T13:15:00Z (GMT) / Submitted by FABIO MILIONI (fmilioni@yahoo.com.br) on 2018-10-03T14:12:34Z No. of bitstreams: 1 Tese Doutorado - Fabio Milioni.pdf: 5835160 bytes, checksum: d954dcaaa0c0bc020baceb52b0107786 (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-10-03T17:15:10Z (GMT) No. of bitstreams: 1 milioni_f_dr_bauru.pdf: 5480525 bytes, checksum: 6ac2fa2e539201d14af3503b4de493a1 (MD5) / Made available in DSpace on 2018-10-03T17:15:10Z (GMT). No. of bitstreams: 1 milioni_f_dr_bauru.pdf: 5480525 bytes, checksum: 6ac2fa2e539201d14af3503b4de493a1 (MD5) Previous issue date: 2018-08-20 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo da presente tese foi verificar a influência da suplementação de β-Alanina associado ao treinamento intervalado de alta intensidade (HIIT) na performance de sprints repetidos. Participaram do estudo conduzido em caráter randomizado e duplo-cego, 20 jovens saudáveis alocados em dois grupos (Gβ [n = 10] – 6,4 g.dia-1 de β-Alanina; GP [n = 10] – 6,4 g.dia-1 de dextrose - placebo). Os participantes foram avaliados em três momentos distintos, previamente ao início, após quatro semanas de HIIT sem suplementação e após 6 semanas de suplementação + HIIT. As avaliações foram compostas por teste incremental até exaustão (TINC); séries de 12 sprints repetidos (RSA); e teste de tempo limite até exaustão a 115% da velocidade máxima atingida no TINC (TLIM). Previamente e imediatamente após TINC e RSA foram realizadas avaliações neuromusculares compostas por saltos verticais máximos, contrações isométricas máximas de extensão de joelho e estimulação elétrica periférica. O HIIT foi composto de dez corridas de 1 min a 90% da velocidade máxima atingida no TINC, com 1 min de recuperação passiva entre as corridas e frequência de 3 sessões semanais. Previamente ao início da suplementação + HIIT e ao final da intervenção, os participantes foram submetidos a biópsias musculares para determinação do conteúdo de carnosina intramuscular, capacidade de tamponamento in vitro e conteúdo de proteínas/enzimas chaves. Após a intervenção, ambos os grupos melhoraram o metabolismo oxidativo (i.e., consumo máximo de oxigênio), entretanto, somente o Gβ melhorou significativamente o conteúdo de carnosina intramuscular e as variáveis do RSA além de apresentar atenuação da fadiga neuromuscular induzida pelo RSA. Não foram verificadas diferenças significativas na capacidade anaeróbia, capacidade de tamponamento in vitro e conteúdo de proteínas/enzimas chaves. Dessa forma, a associação entre suplementação de β-Alanina e HIIT proporcionou melhora significativa do desempenho de sprints repetidos. / The aim of the present thesis was to verify the influence of β-Alanine supplementation associated with high intensity interval training (HIIT) on the performance of repeated sprints. The study was conducted in a randomized, double-blind design and 20 healthy young men were allocated in two groups (Gβ [n = 10] - 6.4 g.day-1 of β-Alanine; GP [n = 10] - 6.4 g.day-1 of dextrose – placebo). The participants were evaluated at three different moments, prior to beginning, after four weeks of HIIT without supplementation and after 6 weeks of supplementation + HIIT. The evaluations were composed by incremental test until exhaustion (TINC); set of 12 repeated sprints (RSA); and time-to-exhaustion test at 115% of the maximum velocity achieved in TINC (TLIM). Previously and immediately after TINC and RSA, neuromuscular evaluations were performed, consisting of maximum vertical jumps, maximal voluntary isometric contractions of knee extension and peripheral electrical stimulation. The HIIT was composed by ten runs of 1-min at 90% of the maximum velocity achieved in TINC, with 1-min of passive recovery between runs and frequency of 3 sessions per week. Prior to the initiation of supplementation + HIIT and at the end of the intervention, the participants underwent muscle biopsies to determine intramuscular carnosine content, muscle buffer capacity in vitro and key protein/enzyme content. After the intervention, both groups improved oxidative metabolism (i.e., maximal oxygen uptake), however, only Gβ significantly improved the intramuscular carnosine content and the RSA variables; in addition to presenting attenuation of the neuromuscular fatigue induced by the RSA. No significant differences were observed in anaerobic capacity, muscle buffer capacity in vitro and key protein/enzyme content. Thus, the association between β-Alanine supplementation and HIIT provided significant improvement in repeated sprints performance. / 2016/02683-6
103

Synthèse métallo-catalysée d'analogues de nucléosides et d'oxazolo[4,5-d]pyrimidines à visée thérapeutique / Metallo-catalysed synthesis of nucleosides analogues and oxazolo[4,5-d]pyrimidines with potential therapeutic applications

Pradere, Ugo 15 December 2009 (has links)
Les nucléosides représentent avec plus de 40 composés approuvés la pierre angulaire des chimiothérapies antivirales. Leur émergence progressive depuis maintenant prés de 50 ans a conduit à des progrès considérables dans la lutte contre de nombreuses infections virales comme les herpès, les hépatites ou le SIDA. Néanmoins, l’apparition de résistances et la toxicité intrinsèque des molécules poussent la recherche à développer de nouveaux analogues nucléosidiques plus actifs et plus surs. Dans cette optique, les réactions organo-métallliques sont des outils efficaces pour la synthèse de nouveaux composés à potentiel thérapeutique. Dans cette thèse, les cycloadditions 1,3 dipolaire de Sharpless catalysées au Cu et au Ru et les réactions de métathèse, croisée ou par fermeture de cycle catalysées au Ru, nous ont ainsi permis de synthétiser efficacement trois nouvelles séries d’analogues nucléosidiques modifiés. Enfin, la synthèse d’une nouvelle série de composés hétérocycliques de type oxazolopyrimidine à chaine β-dicétoacide ciblant l’inhibition de l’intégrase du VIH a été initiée, mettant notamment en jeu des réactions de couplage pallado-catalysées. / Nucleosides represent with more than 40 compounds approved the cornerstone of antiviral chemotherapy. Their gradual emergence from now nearly 50 years has led to considerable progress in the fight against many viral infections such as herpes, hepatitis or AIDS. Nevertheless, the emergence of resistance and the molecule inherent toxicity prompt the research to develop new nucleoside analogues with higher activities and safety. In this context, organometallic reactions are effective tools for the synthesis of new compounds with therapeutic potential. In this thesis, the Sharpless Cu and Ru catalyzed 1,3 dipolar cycloadditions and the Ru catalyzed cross and ring closing metathesis allowed us to synthesize efficiently three new series of modified nucleoside analogues. Finally, the synthesis of a new series of oxazolopyrimidine heterocyclic compounds wearing a β-diketoacid chain and targeting the inhibition of HIV integrase has been initiated, using palladium catalyzed coupling.
104

Conception et synthèse d'iminoglycolipides comme inhibiteurs d'enzymes lysosomales à effet chaperon pharmacologique / Conception and synthesis of iminoglycolipids as inhibitors of lysosomal enzymes acting as pharmacological chaperones

OulaÏdi, Farah 28 January 2011 (has links)
La thérapie chaperon représente une approche thérapeutique stratégique et innovante, en particulier dans le traitement des maladies lysosomales. Ces maladies génétiques rares ont une gravité variable, qui peut aller de la létalité avant la naissance jusqu’à la nécessité d‟une prise en charge permanente ; elles apparaissent à tous les stades de la vie. Des mimes du substrat appelé iminosucres, vont agir en allant au coeur du site actif de l’enzyme, stabiliser l’enzyme mutée qui est instable mais non inactive. Paradoxalement, la plupart des chaperons pharmacologiques sont des inhibiteurs de l’enzyme visée mais leur administration à faible concentration leur permet de réaliser leur mission de sauvetage de l’enzyme mutée. Dans cette optique, des recherches effectuées au sein de notre laboratoire ont fait état de la synthèse d’iminosucres, tels que les α-1-C-alkyl iminoxylitols qui sont de très bons inhibiteurs de la β-glucocérébrosidase, l’enzyme défaillante dans la maladie de Gaucher, mais aussi qui doublent l’activité enzymatique résiduelle. Une nouvelle voie de synthèse plus efficace a été réalisée afin d’obtenir plus efficacement ce type d’iminosucres et d’autres dérivés. Ces travaux ont également été l’occasion de développer des iminoxylitols structurellement simplifiés qui agissent comme chaperons pharmacologiques toujours pour le traitement de la maladie de Gaucher. Une partie de ces travaux a aussi été consacrée à la recherche d‟inhibiteurs de la β-galactocérébrosidase, l’enzyme impliquée dans la maladie de Krabbé, et qui pourront agir comme chaperons pharmacologiques. Différentes évaluations pharmacologiques ont été réalisées, notamment des tests d’inhibition et la détermination des effets chaperons. / Chaperone Mediated Therapy represents an innovative and strategic approach to treat lysosomal storage disorders which a class of rare genetic diseases. Competitive inhibitors for some of these lysosomal enzymes can, at sub inhibitory concentrations, act as chaperones and rescue the mutant proteins. In fact, enzymes carrying some mutations are still catalytically active. α-1-C-alkyl iminoxylitols represent a class of iminosugars which mimic the “gluco” configuration of the substrate and give powerful inhibitors of β-glucocerebrosidase, the enzyme involved in Gaucher disease. Moreover, this class of iminosugars, synthesized by our group, act as pharmacological chaperones and are able to double the residual activity of the N370S mutant. In order to synthesize more efficiently these iminosugars, the synthetic strategy was improved and optimized. Moreover, we focused our investigations on structural variations on our lead compound (α-1-C9 iminoxylitol) and draw important conclusions on structure-activity relationship. Then, we extended our expertise on iminosugars as pharmacological chaperones to another lysosomal glycosidase. In paricular, we targeted β-galactocerebrosidase, the enzyme responsible for Krabbe disease, and synthesized a series of iminosugars which mimic the “galacto” configuration. Biological assays were performed on our compounds to determine their activity as inhibitors and for some of them, their chaperone effects.
105

Efeito da metil-b-ciclodextrina e de alguns tensoativos sobre a viabilidade celular de linhagens celulares de câncer de ovário

Gonçalves, Nahun Thiaghor Lippaus Pires 16 August 2011 (has links)
Made available in DSpace on 2016-08-29T15:34:27Z (GMT). No. of bitstreams: 1 tese_4971_Dissertação_Nahun Thiagor.pdf: 1844062 bytes, checksum: 8e3e54f1750887fb5387ffffb0103629 (MD5) Previous issue date: 2011-08-16 / No presente estudo é estabelecida uma correlação entre alguns tensoativos, um derivado de ciclodextrina, oligossacarídeo cíclicos originado da ação da ciclodextrina glicosiltransferase, a β-ciclodextrina metilada e as linhagens de câncer de ovário A 2780 e OVCAR 3, tentando abrir a possibilidade de utilização da ciclodextrina associada a medicamentos quimioterápicos padronizados à terapia contra o câncer de ovário, que é apontado como uma das principais causas de óbito entre as malignidades ginecológicas. O câncer de ovário apresenta alta taxa de mortalida, além de possuir vários subtipos histo-clínicos, a cada ano aumenta cada vez mais o número de pacientes diagnosticadas, assim, é indispensável à continuidade das pesquisas científicas relacionadas a este tipo de câncer, visto que os conhecimentos até então elaborados são de extrema significância, porém insuficientes para que seja estabelecida uma cura. Através da viabilidade celular pelo método do MTT, onde se utiliza o sal de tetrazol para expressar de forma quantitativa a proliferação e sobrevivência das células e o método de BRADFORD, para normalização de dados, tenta-se estabelecer a influência de alguns tensoativos e do derivado de ciclodextrina sobre e entre as linhagens de câncer de ovário. A metil-β-ciclodextrina e os tensoativos SDS, TX100 E TW20 induziram uma redução da atividade mitocondrial dose-dependente em cultura de células de câncer de ovário da linhagem A 2780 e OVCAR 3. O derivado de ciclodextrina demonstrou indução gradativa da redução da atividade mitocondrial para duas das oito concentrações testadas (0,2% e 0,4%) com viabilidade celular próxima a 60% na linhagem A 2780. Na linhagem OVCAR 3 a metil-β-ciclodextrina apresenta potencial citotóxico capaz de inviabilizar 25% do crescimento celular em concentrações superiores a 0,003125%, a viabilidade celular perante as mesmas condições de tratamento é menor nesta linhagem quando comparada a linhagem A 2780. Devido às propriedades da ciclodextrinas os resultados das análises comparativas de viabilidade celular, nas linhagens de câncer de ovário, estes resultados apontam para possibilidades maiores em futuros estudos, podendo a pesquisa aqui apresentada ser tomada como referência. / This study sets up a correlation between some surfactants, a derivate of cyclodextrin, cyclic oligosaccharide originated from the action of the glycosyltransferase cyclodextrin, a methyllated β-cyclodextrin and the lines of ovarian cancer A 2780 and OVCAR 3, trying to offering the possibility of using cyclodextrin associated with standard chemotherapy drugs in therapy against ovarian cancer, which is pointed as one of the main causes of death among gynecological ills. Ovarian cancer is connected with high mortality rate and has several histo-clinical subtypes, raising the number of patient diagnosed each year, therefore there are the needy of continuing the scientific research which this kind of cancer is related, once the knowledge developed so far are extremely significant, yet it still is insufficient to generate a cure. Through the cellular viability by MTT method, which uses salt of tetrazol to express quantitatively the proliferation and survival of cells, and Bradford method for standardization data, it attempts to establish the influence of surfactants and some of the derivate of cyclodextrin on and between the lines of ovarian cancer. The methyl-β-cyclodextrin and the surfactant SDS, TX100 and TW20 induced a reduction in dose-dependent mitochondrial activity in cell cultures of ovarian cancer line A 2780 and OVCAR 3. The cyclodextrin derivate has demonstrated induction of gradual reduction of the mitochondrial activity of two from eight concentrations tested (0,2% and 0,4%) with cell viability of approximately 60% in strain A 2780. In the line OVCAR 3 the methyl-β-cyclodextrin shows potential cytotoxic able to tamper 25% of cell growth in conditions of treatment is reduced in this strain when compared with strain A 2780. Due to the properties of cyclodextrins, results of comparative analyzes of cell viability, in the strains of ovarian cancer, indicates to greater possibilities in future studies, enabling the research presented here as a reference.
106

Avaliação da produção de β-lactamase em pseudomonas aeruginosa obtidas de dois Hospitais de Porto Alegre

Gonçalves, Ana Lúcia Saraiva January 2005 (has links)
Objetivos: Avaliar o perfil de suscetibilidade, a prevalência da produção de AmpC, β-lactamase de espectro estendido (ESBL) e Metalo-β-lactamase (M-βla) em Pseudomonas aeruginosa obtidas de dois hospitais universitários distintos (ISCMPA e HCPA) em Porto Alegre. Em adição, tipagem molecular por PFGE foi realizada entre os isolados produtores de M-βla para avaliar a relação clonal. Métodos: Foi determinada a suscetibilidade de 238 isolados de P. aeruginosa para 8 agentes antimicrobianos, através do teste de disco-difusão, usando agar Müller-Hinton (MH) de acordo com “National Committee for Clinical Laboratory Standards” (NCCLS) . Todos isolados foram avaliados para produção de AmpC com o disco de imipenem (indutor) próximo ao disco de cefepima/ceftazdima (substrato). Um achatamento no halo de cefepime/ceftazidima pela indução da enzima pelo imipenem, indicava resultado positivo para AmpC. Todos isolados forma avaliados para a presença de ESBL através do teste de aproximação de disco com ceftazidima, cefepima, cefotaxima, ceftriaxona e ticarcilina-clavulanato como inibidor de β-lactamase. A produção de M-βla foi determinada através do teste de aproximação de discos de CAZ a discos impregnados com ácido2-mercatopropiônico (2-MPA). As taxas de resistência foram comparadas através do Teste Exato de Fisher. Valor de P<0,05 foi considerado estatisticamente significativo. Análise de macrorestrição com a enzima speI foi realizada em isolados produtores de M-βla. Resultados: As taxas de resistência para todos os agentes foram superiores entre os isolados obtidos na ISCMPA em relação aos do HCPA. A ceftazidima mostrou ser o antibiótico mais efetivo contra os isolados de ambos Hospitais (ISCMPA e HCPA) com taxa de resistência de 25,7% (ISCMPA) e 6,1% (HCPA). A expressão de AmpC foi observada em 190 isolados (83,7% HCPA e 77,1% ISCMPA). Não foi possível detectar a presença de ESBL entre todos as P. aeruginosa avaliadas em ambos hospitais. Foi observada a presença de M-βla em 28 isolados (20,0%) da ISCMPA. Mas não foi detectada M-βla em nenhuma P. aeruginosa do HCPA. A análise de macrorestrição mostrou que 14 de 16 P. aeruginosa Mβla positivas pertenciam a um clone (denominado clone A), e seus subclones. Apenas dois outros clones (B e C) foram identificados em um isolado cada. / Objectives: To evaluate susceptibility profile, the prevalence of extendedspectrum β-lactamases (ESBL) production, AmpC and Metallo-β-lactamases (M-βla) in Pseudomonas aeruginosa obtained from two distinct hospitals (ISCMPA and HCPA) in Porto Alegre, Brazil. In addiction, molecular typing by PFGE was perfomed among isolates producing M-βla in order to evaluate probably clonal relatedness. Methods: The susceptibility of 238 P. aeruginosa to 8 antimicrobial agents was determined by the disk diffusion method, using Müller-Hinton agar (MH) in accordance with “National Committee for Clinical Laboratory Standards” guidelines. All isolates were evaluated for AmpC production with the imipenem disk (strong inducer) near of the cefepime/ceftazidime disk (substrate). A blunting of the cefepime/ceftazidime zone by imipenem-induced enzyme, indicated positive result for AmpC. All isolates were evaluated for ESBL production by disk approximation test with ceftazdime, cefepime, cefotaxime, ceftriaxone plus ticarcillin-clavulanate as inhibitor. M-βla production was determined by disk approximation test with disks containing CAZ and 2-mercatopropionic acid (2-MPA). The results were compared by the Fisher’s Exact Test. Macrorestriction analysis by SpeI, followed by PFGE, was perfomed in isolates M-βla positive. The resistance rates were compared by The Fisher’s Exact Test. P values < 0.05 were considered to be statistically significant. Results: The resistance rates to all antimicrobial agents were higher among isolates obtained from ISCMPA than those obtained from HCPA. The ceftazidime was the more active antibiotic against the isolates in both hospitals with resistance rates of 25,7% (ISCMPA) and 6,1% (HCPA). The derepression of AmpC was observed in 190 isolates (83,7% HCPA and 77,1% ISCMPA). It was not possible to detect the presence of ESBL among all P. aeruginosa evaluated in both hospitals. Positive results for M-βla production were observed in 28 isolates (20,0%) from ISCMPA. But none M-βla production was identified in P. aeruginosa from HCPA. The macrorestriction analysis by PFGE, showed that 14 of 16 M-βla positive P. aeruginosa beloneed to one clone (named clone A) and its subclones.Only two others clones (B and C) were identified in one isolate each.
107

Identificação de metalo-β-lactamases em bacilos gram-negativos não fermentadores isolados no Hospital Universitário de Santa Maria / Identification of metallo-β-lactamases in nonfermentative gram negatives bacilli isolated in University Hospital of Santa Maria

Bertoncheli, Claudia de Mello 18 January 2008 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / In recent years, the isolation of bacteria producing β-lactamases has caused concern around the world, due to the fact these enzymes hydrolysis the ring β-lactam antimicrobials used in the main clinic. This aim of this study was asses the prevalence metallo-β-lactamases (MbL) in isolates of Pseudomonas aeruginosa and Acinetobacter baumannii obtained from patients admitted at the University Hospital of Santa Maria (HUSM). The profile of susceptibility for all isolates was evaluated by the disk diffusion method standardized by CLSI. The antimicrobial disks were distributed in a way that allows the identification of strains producers of AmpC and ESBL. For the identification of the producers of MbL the test of disk approximation with EDTA 0.1 M, EDTA 0,5M and acid 2-mercaptopropionic were performed. Isolates that did not have any of the mechanisms of resistance search were classified as multiresistant (MDR). The minimum inhibitory concentration (MIC) for ceftazidima, imipenem and polymyxin B was assessed by broth method microdilution for all isolated, according to CLSI. From January to June 2006, were obtained 32 isolates the P.aeruginosa and 41 the A. baumannii, the those 17 (23.29%) were β-lactamase AmpC-type producers, 11 (15.07%) were MbL producers, and 45 (61,64%) were classified as MDR. All strains producing MbL were Pseudomonas aeruginosa. The sensitivity of the isolates according to the CIM for antimicrobial evaluated were: 90,28% for polymyxin B, 36,11% for imipenem and 18% for ceftazidima. There was a high prevalence of MDR isolates and producers of β-lactamase-type AmpC and MbL in HUSM, this is extremely worrying once there is limiting therapy available. This situation becomes even more worrying with the find of isolates resistant the polymyxin B, witch is one of the last options of treatment for MDR isolates and producers of MbL. The detection of microorganisms is extremely important for the committees of infection hospital with the goal of preventing outbreaks, as well as guide the medical team on the conduct therapy, since there are few effective antimicrobial clinically for these pathogens and no prospects for development the new antimicrobial in the near future. / Nos últimos anos, o isolamento de bactérias produtoras de β-lactamases tem causado preocupação em todo o mundo, devido ao fato dessas enzimas hidrolisarem o anel β- lactâmico dos principais antimicrobianos utilizados na clínica. Este trabalho teve por objetivo avaliar a prevalência de metalo-β-lactamases (MbL) em isolados de Pseudomonas aeruginosa e Acinetobacter baumannii obtidos de pacientes atendidos no Hospital Universitário de Santa Maria (HUSM). O perfil de sensibilidade para todos os isolados foi avaliado pelo método de disco difusão padronizado pelo CLSI. Os discos de antimicrobianos utilizados foram distribuídos de forma que permitisse a identificação dos isolados produtores de AmpC e ESBL. Para a identificação dos produtores de MbL utilizou-se o teste de disco aproximação com os seguintes agentes quelantes: EDTA 0,1M, EDTA 0,5 M e ácido 2-mercaptopropiônico. Os isolados que não possuíam nenhum dos mecanismos de resistência pesquisados foram classificados como multirresistentes (MDR). A concentração inibitória mínima (CIM) para ceftazidima, imipenem e polimixina B foi avaliada pelo método de microdiluição em caldo para todos os isolados, de acordo com o CLSI. Durante o período de janeiro a junho de 2006 foram obtidos 32 isolados de P.aeruginosa e 41 de A. baumannii, destes 17 (23,29%) foram produtores de β-lactamase do tipo AmpC, 11 (15,07%) foram produtores de MbL e 45 (61,64%) foram classificados como MDR. Todas as cepas produtoras de MbL foram de Pseudomonas aeruginosa. A sensibilidade dos isolados de acordo com a CIM para os antimicrobianos avaliados foram as seguintes: 90,28% para polimixina B, 36,11% imipenem e 18% ceftazidima. Observou-se uma alta prevalência de isolados MDR no HUSM, além de isolados produtores de β-lactamase do tipo AmpC e MbL, o que é extremamente preocupante devido limitar a terapia a poucos antimicrobianos. Esta situação torna-se ainda mais preocupante com a detecção de isolados resistentes a polimixina B, a qual é uma das últimas opções de tratamento para infecções causadas por isolados de P. aeruginosa e Acinetobacter baumannii MDR e produtores de MbL. A detecção desses microrganismos é de grande importância para as comissões de controle de infecção hospitalar com o objetivo de prevenir surtos, bem como orientar a equipe médica sobre a conduta terapêutica, uma vez que há poucos antimicrobianos efetivos clinicamente para esses patógenos e as perspectivas para o desenvolvimento de novos antimicrobianos em um futuro próximo são mínimas.
108

Síntese de novos azóis derivados da 1,1- difenilacetona / Synthesis of new azoles derivatives of 1,1 diphenylacetone

Friedein, Alynne Alegre Souto 07 August 2014 (has links)
This work describes an efficient method to obtaining new heterocycles from the reaction of acetalization of the ketonic carbonyl, followed by acylation of the enolether, generated in situ from the acetal derivative of 1,1-diphenylacetone, with trifluoroacetic anhydride, tricloroacetila of chloride, clorodiflúoracético anhydride, pentaflúorpropiônico anhydride in the absence of solvents. There were performed reactions of cyclocondensation between 1,1,1-trialo-4-alkoxy-3-alquen-2-ones and hydroxylamine hydrochloride, forming, in general, the 5-trialometil-5-hydroxy-4,5-diidroisoxazóis. To obtaining pyrazoline compounds, was proposed the cyclocondensation between the β-ketones alcoxivinil (ou é β-alcoxivinil ketones?) and four different dinucleophiles: monohydrate hydrazine, phenylhydrazine, thiosemicarbazide and aminoguanidine carbonate. All compounds synthesized on this work, since the acetal to the final heterocycles are inedited and their structures were confirmed by RMN 1H e 13C data. In this work, were also performed antimicrobial activity tests of some compounds against microorganisms, wherein some showed significant result for bacteria of great clinical interest, Staphylococcus aureus. / Este trabalho descreve um método eficiente para a obtenção de novos heterociclos a partir da reação de acetalização da carbonila cetônica, seguida pela acilação do enoléter, gerado in situ a partir do acetal derivado da 1,1-difenilacetona, com anidrido trifluoracético, cloreto de tricloroacetila, anidrido clorodiflúoracético e anidrido pentaflúorpropiônico na ausência de solventes. Foram realizadas reações de ciclocondensação entre as 1,1,1-trialo-4-alcoxi-3-alquen-2-onas e cloridrato de hidroxilamina, formando, de maneira geral, os 5-trialometil-5-hidroxi-4,5-diidroisoxazóis. Para obtenção dos compostos pirazolínicos, foi proposta a ciclocondensação entre as β-alcoxivinil cetonas e quatro diferentes dinucleófilos: monohidrato de hidrazina, fenilhidrazina, tiosemicarbazida e carbonato de aminoguanidina. Todos os compostos sintetizados neste trabalho, desde o acetal até os heterociclos finais são inéditos e suas estruturas foram confirmadas por dados de RMN 1H e 13C. Neste trabalho, também foram realizados testes de atividade antimicrobiana de alguns compostos contra microorganismos, sendo que alguns apresentaram significativo resultado para a bactéria de grande interesse clínico, Staphylococcus aureus.
109

Novel nucleoside analogues with bases modified with (β-halo)vinyl sulfone or β-keto sulfone as probes to study RNA/DNA-Proteins interactions

Suzol, Sk Md Sazzad Hossain 28 June 2017 (has links)
The C-5 modified pyrimidine analogues are well-known anticancer and antiviral drugs which underscore further development of novel probes to study their physical, chemical, and biological properties. In my dissertation the syntheses and properties of (β-halo)vinyl sulfone and/or (β-keto)sulfone analogues of C-5 modified pyrimidine have been discussed. In the first part of the dissertion, the synthesis of 5-(β-halo)vinyl sulfones either by transition metal-catalyzed or iodine-mediated halosulfonylation reaction of 5-acetylene pyrimidine nucleosides have been explored. The novel (β-chloro/bromo/iodo)vinyl sulfones efficiently undergo addition-elimination reaction with different nucleophiles such as thiols, amines, amino acid, peptides to provide (β-substituted)vinyl sulfone analogues. The rate of these substitution reactions depends on the nature of halogen atom presents at the β-position and increases with the order of I ≥ Br > Cl. (β-chloro/bromo/iodo)vinyl sulfones possess exclusively E stereochemistry while their β-substitued analogues possess either E (for β–thio analogues) or Z (for β–amino analogue) stereochemistry. It has been observed that the vinylic proton of (β-chloro) or (β-amino)sulfone analogue undergoes exchanges with deuterium in polar protic deutorated solvents. The antiproliferative activities of those analogues have been explored and was found that protected 5-(E)-(1-chloro-2-tosylvinyl)-2'-deoxyuridine inhibited the growth of L1210, CEM and HeLa cells in lower micromolar range. In the second part of the dissertation the syntheses and reactivities of 5-(β-keto) sulfone of pyrimidine nucleosides were investigated. Thus, 5-(β-halovinyl)sulfone of uracil and cytosine nucleosides have been efficiently converted into corresponding 5-(β-keto) sulfone analogues by displacement of halogen with ammonia followed by acid-catalyzed hydrolysis of the resulting (β-amino)sulfone analogues. A number of electrophiles were trapped at the acidic α-carbon of the 5-(β-keto)sulfones by treatment with electrophiles such as methyl, benzyl, or allyl halide in the presence of base. The 5-(α-iodo-β-keto)sulfone analogues of uracil nucleosides have been tested as an alternative substrates to probe the incorporation of nucleophiles at α-carbon. In the third part of the dissertation, the synthesis of 5'-phosphates of 5-(β-chloro) and 5-(β-keto) sulfones of 2'-deoxyuridine and their polymerase-catalyzed incorporation into DNA were evaluated. Thus, 5'-O-phosphorylated analogues have been efficiently incorporated into the DNA by human DNA repair polymerase (pol β) or bacterial polymerase (pol I).
110

Resistência a antimicrobianos e diversidade de β-lactamases em Escherichia coli de origem aviária / Antimicrobial resistance and β-lactamases diversity in Escherichia coli from poultry

Oliveira Filho, José Carlos de 04 October 2006 (has links)
Made available in DSpace on 2015-03-26T13:51:59Z (GMT). No. of bitstreams: 1 01 - capa_abstract.pdf: 112846 bytes, checksum: f260bcc7fb2e9aa227782fd9e02a5c86 (MD5) Previous issue date: 2006-10-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The diversity of resistance mechanisms to antimicrobial compounds was investigated in E. coli strains isolated from poultry. All 30 isolates were resistant to ampicillin and 26 of them were resistant to at least two antibiotics. Multi-resistance profiles were confirmed, including intermediate levels. Forty percent of the strains presented four resistance markers and 93% of the isolates were resistant to tetracycline, an antibiotic commonly used in poultry farms. The β-lactamase diversity among the strains was probed against seven compounds. Among strains bearing the same resistance profile for other groups of antimicrobial drugs, it was possible to observe different β-lactamases activity against the tested substrates. This fact suggests either a pool of resistance genes or regulatory differences. The isolate that displayed confirmed activity against six of the β-lactamic antibiotics bears a large molecular mass plasmid that confers the AmpR phenotype. A fragment of this plasmid with approximately 5 kb was subcloned in the pCCR9 vector which is commonly used to detect β-lactamase genes. The amino acid deduced from nucleotide sequencing displayed 100% of identity to TEM-1, a class A serine β-lactamase. Next to the gene encoding TEM-1 was found putative transposon related to the Tn3 family, albeit with some differences in the order and direction of transcription of the genes. / A diversidade dos mecanismos de resistência a antimicrobianos foi investigada em Escherichia coli, originadas de frangos de corte. Dos 30 isolados, todos resistentes à ampicilina, 26 apresentaram mais de uma marca de resistência. Foram confirmados modelos de multirresistência, incluindo níveis intermediários de resistência. Em 40% dos casos, ocorreram quatro marcas e 93% dos isolados resistiram à ação de tetraciclina, um promotor de crescimento usual na agropecuária. A diversidade de β-lactamases entre os isolados foi demonstrada pela ação direta contra sete β-lactâmicos. Os isolados com mesmo modelo de resistência possuíam, sob mesmas condições, espectro de ação e de atividade diferentes, mostrando que há amplo pool de genes de resistência, ou diferenças regulatórias nessas bactérias. O isolado com maior espectro de ação, confirmado sobre seis β-lactâmicos, contém um plasmídeo de alta massa molecular, que confere resistência a ampicilina. Um fragmento deste plasmídeo, com aproximadamente 5 kb, foi clonado em pCCR9, vetor usado para detecção de genes de resistência a β-lactâmicos. As análises das seqüências obtidas revelaram 100 % de identidade com TEM-1, uma serina β-lactamase da classe A. Próximo ao gene codificador da TEM-1, foi encontrado um transposon putativo relacionado com os da família Tn3, porém com particularidades na ordem e direção de transcrição dos genes componentes.

Page generated in 0.0358 seconds