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Estimador de erro a posteriori baseado em recuperação do gradiente para o método dos elementos finitos generalizados; A posteriori error estimator based on gradient recovery for the generalized finite element method

Lins, Rafael Marques
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/05/2011 Português
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O trabalho aborda a questão das estimativas a posteriori dos erros de discretização e particularmente a recuperação dos gradientes de soluções numéricas obtidas com o método dos elementos finitos (MEF) e com o método dos elementos finitos generalizados (MEFG). Inicialmente, apresenta-se, em relação ao MEF, um resumido estado da arte e conceitos fundamentais sobre este tema. Em seguida, descrevem-se os estimadores propostos para o MEF denominados Estimador Z e "Superconvergent Patch Recovery" (SPR). No âmbito do MEF propõe-se de modo original a incorporação do "Singular Value Decomposition" (SVD) ao SPR aqui mencionada como SPR Modificado. Já no contexto do MEFG, apresenta-se um novo estimador do erro intitulado EPMEFG, estendendo-se para aquele método as idéias do SPR Modificado. No EPMEFG, a função polinomial local que permite recuperar os valores nodais dos gradientes da solução tem por suporte nuvens (conjunto de elementos finitos que dividem um nó comum) e resulta da aplicação de um critério de aproximação por mínimos quadrados em relação aos pontos de superconvergência. O número destes pontos é definido a partir de uma análise em cada elemento que compõe a nuvem, considerando-se o grau da aproximação local do campo de deslocamentos enriquecidos. Exemplos numéricos elaborados com elementos lineares triangulares e quadrilaterais são resolvidos com o Estimador Z...

Visualizador 3D baseado em head tracking e estereoscopia para aplicações com o método dos elementos finitos.; 3D viewer based on head tracking and stereoscopic for finite element method applications.

Junqueira, Luiz Antonio Custódio Manganelli
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/12/2013 Português
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A visualização 3D de simulações pelo Método dos Elementos Finitos (MEF) ainda é uma experiência limitada em função da falta de realismo 3D nos monitores disponíveis. Além do monitor 3D realista, a melhor visualização destas simulações depende de uma apresentação MEF desenvolvida adequadamente, de forma a tirar maior proveito deste realismo 3D. Neste trabalho, é realizado o desenvolvimento de um visualizador MEF 3D, que reproduz os efeitos estereoscópicos e de rastreamento de cabeça (head-tracking), explorando melhor as percepções de profundidade com hardware acessível e bibliotecas gráficas utilizadas em aplicações convencionais.; The 3D visualization of Finite Element Method (FEM) simulations is still a limited experience due to the lack of realism of 3D monitors available. In addition to the realistic 3D monitor, better visualization of these simulations depends on a MEF presentation properly developed in order to get the most out of 3D realism. In this work, a 3D MEF viewer is develop, including stereoscopy and head tracking 3D effects, that better explores human depth cues using hardware from cost and benefit perspective and graphics libraries used in conventional applications.

Distribuição das tensões geradas ao redor de implantes osseointegrados de diferentes conexões cone morse: análise fotoelástica e pelo método dos elementos finitos

Anami, Lilian Costa
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 111 f. : il. color.
Português
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Odontologia Restauradora - ICT; O objetivo deste trabalho foi avaliar a localização e distribuição das tensões geradas ao redor de implantes com pilares protéticos de diferentes conexões cone Morse através da análise fotoelástica (AFE) e do método dos elementos finitos (MEF). Para o MEF, implante e pilares protéticos de diferentes conexões cone Morse (hexagonado e sólido) foram digitalizados pela técnica da microtomografia computadorizada e, com auxílio de softwares computacionais foi realizada a modelagem da malha tridimensional e o carregamento dos objetos. Foi realizada a caracterização das propriedades mecânicas da resina fotoelástica. Foram simulados blocos com propriedades mecânicas de osso cortical e trabecular e de resina fotoelástica. A AFE foi realizada a partir de blocos de resina fotoelástica onde foram incluídos os implantes aparafusados aos diferentes pilares protéticos. Estes blocos foram confeccionados a partir de um bloco prototipado do modelo utilizado no MEF. Os corpos-deprova foram imersos em um recipiente com óleo mineral e o conjunto foi observado no polariscópio circular com dispositivo de aplicação de cargas acoplado e recebendo a mesma carga...

Analise vibro-acustica utilizando o metodo de elementos finitos com mapeamento Dirichlet-to-Neumann (DtN)

Paulo Alexandre Galarce Zavala
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/05/1999 Português
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Neste trabalho buscou-se um Método de Acoplamento Fluido-Estrutura que levasse em consideração a presença de meio fluido infinito. Após uma revisão de literatura sobre tratamento de meios infinitos, adotou-se o Método Dirichlet-to-Neumann (DtN), por ser exato, não reflexivo e podendo ser diretamente inserido no Método de Elementos Finitos (MEF) usado na modelagem Fluido-Estrutura. Assim, a modelagem clássica em elementos finitos para meios estrutural e fluido são apresentadas conjuntamente com a formulação para alguns elementos simples bi-dimensionais. O Método DtN para meios fluido infinitos e semi-infinitos é apresentado junto com sua forma discretizada para inclusão no MEF, sendo discutida suas principais implicações. Um Método de Expansão de Resultados para fora do domínio discretizado é apresentado. A modelagem Fluido-Estrutura em meio fluido infinito usando-se o Mapeamento DtN (MEF jDtN) é apresentada. Na sequência, é feita a investigação do Método DtN, com a validação da implementação adotada, análise da influência dos parâmetros do Método DtN e análise do Método de Expansão dos Resultados. Para a investigação da modelagem Fluido-Estrutura com Mapeamento DtN foram escolhidos dois exemplos...

Modelagem multidimensional de transporte de contaminantes inorgânicos em solos tropicais lateríticos

Díaz Sánchez, Juan Fernando
Fonte: Universidade de Brasília Publicador: Universidade de Brasília
Tipo: Dissertação
Português
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Dissertação (mestrado)—Universidade de Brasília, Departamento de Engenharia Civil, Programa de Pós-Graduação em Geotecnia, 2011.; Uma serie de substâncias contaminantes constituídas principalmente por íons de metais pesados foram aplicados sobre corpos de prova moldados por solos lateríticos em condições in-situ e compactados. Os parâmetros ajustados de transporte foram determinados utilizando metodologias de minimização do erro entre a concentração relativa medida experimentalmente e a concentração relativa calculada através de uma solução analítica unidimensional para, finalmente, obter o coeficiente de dispersividade longitudinal (x) e o coeficiente de retardo (R). Por meio de uma análise paramétrica e de sensibilidade utilizando a mesma solução analítica unidimensional foi possível estimar qualitativa e quantitativamente, respectivamente, qual dos parâmetros afeta de forma marcante o avanço da pluma contaminante para os materiais estudados. Alguns autores na ultima década enumeraram diferentes revisões feitas nas soluções analíticas tridimensionais de Domenico & Robbins e Domenico, indicando que existem opiniões que divergem com respeito ao rendimento destas duas soluções. Devido a este fato alguns autores centraram suas pesquisas em compreender a natureza das aproximações envolvidas na solução de analítica tridimensional de Domenico através de uma análise matemática rigorosa sobre a origem e desenvolvimento desta solução. Fundamentado nesta proposta...

Observação e controlo da segurança estrutural de barragens de betão: utilização integrada de modelos numéricos e de modelos de separação de efeitos

Mendes, Emanuel Jesus Guerreiro
Fonte: Instituto Politécnico de Lisboa Publicador: Instituto Politécnico de Lisboa
Tipo: Dissertação de Mestrado
Publicado em /11/2014 Português
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Atualmente, o controlo da segurança estrutural de barragens de betão em fase de exploração tende a apoiar-se em sistemas de monitorização que permitem a recolha automática e a recolha manual dos dados da observação. Estes dados são armazenados computacionalmente em bases que podem ser acedidas via web através de sistemas informáticos (web systems) especificamente desenvolvidos para apoiar as atividades de gestão e controlo da segurança. Estes sistemas informáticos são parte integrante dos sistemas de monitorização de barragens e devem: i) ser dotados de interfaces gráficas que permitam uma grande interatividade; ii) permitir armazenar e consultar os dados da observação sob a forma numérica; iii) permitir a visualização gráfica das diversas grandezas observadas ao longo do tempo. Devem também disponibilizar módulos para: i) analisar a evolução ao longo do tempo das grandezas observadas com base em modelos de separação de efeitos (MSE); ii) utilizar modelos de elementos finitos (MEF) para simular o comportamento observado, sob a ação das principais solicitações; e iii) comparar as observações e os resultados dos MSE e MEF. Neste sentido...

Mechanisms of Macrolide Resistance among Streptococcus pneumoniae Isolates from Russia▿

Reinert, Ralf R.; Filimonova, Olga Y.; Al-Lahham, Adnan; Grudinina, Svetlana A.; Ilina, Elena N.; Weigel, Linda M.; Sidorenko, Sergey V.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
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Among 76 macrolide-nonsusceptible Streptococcus pneumoniae isolates collected between 2003 and 2005 from Central Russia, the resistance mechanisms detected in the isolates included erm(B) alone (50%), mef alone [mef(E), mef(I), or a different mef subclass; 19.7%], or both erm(B) and mef(E) (30.3%). Isolates with dual resistance genes [erm(B) and mef(E)] belonged to clonal complex CC81 or CC271.

Recruitment of CREB1 and Histone Deacetylase 2 (HDAC2) to the Mouse Ltbp-1 Promoter Regulates its Constitutive Expression in a Dioxin Receptor-dependent Manner

Gomez-Duran, Aurea; Ballestar, Esteban; Carvajal-Gonzalez, Jose M.; Marlowe, Jennifer L.; Puga, Alvaro; Esteller, Manel; Fernandez-Salguero, Pedro M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Latent TGFβ-binding protein 1 (LTBP-1) is a key regulator of TGFβ targeting and activation in the extracellular matrix. LTBP-1 is recognized as a major docking molecule to localize, and possibly to activate, TGFβ in the extracellular matrix. Despite this relevant function, the molecular mechanisms regulating Ltbp-1 transcription remain largely unknown. Previous results from our laboratory revealed that mouse embryonic fibroblasts (MEF) lacking dioxin receptor (AhR) had increased Ltbp-1 mRNA expression and elevated TGFβ activity, suggesting that AhR repressed Ltbp-1 transcription. Here, we have cloned the mouse Ltbp-1 gene promoter and analysed its mechanism of transcriptional repression by AhR. Reporter gene assays, AhR over-expression and site-directed mutagenesis showed that basal Ltbp-1 transcription is AhR-dependent. Chromatin immunoprecipitation (ChIP) and RNA interference (RNAi) revealed that AhR regulates Ltbp-1 transcription by a mechanism involving recruitment of co-activators such as CREB1 and co-repressors such as HDAC2 to the Ltbp-1 promoter. In AhR-expressing (AhR+/+) MEF cells, the recruitment of HDAC1, 2 and 4 correlated with decreased K8H4 acetylation and impaired binding of pCREBSer133 to the Ltbp-1 promoter, likely maintaining a constitutive repressed state. AhR−/− MEF cells had the opposite pattern of HDACs and pCREB1Ser133 binding to Ltbp-1 promoter...

Distribution of Serotypes, Genotypes, and Resistance Determinants among Macrolide-Resistant Streptococcus pneumoniae Isolates ▿

Xu, Xiaoping; Cai, Lin; Xiao, Meng; Kong, Fanrong; Oftadeh, Shahin; Zhou, Fei; Gilbert, Gwendolyn L.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
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Macrolide resistance in Streptococcus pneumoniae has emerged as an important clinical problem worldwide over the past decade. The aim of this study was to analyze the phenotypes (serotype and antibiotic susceptibility), genotypes (multilocus sequence type [MLST] and antibiotic resistance gene/transposon profiles) among the 31% (102/328) of invasive isolates from children in New South Wales, Australia, in 2005 that were resistant to erythromycin. Three serotypes—19F (47 isolates [46%]), 14 (27 isolates [26%]), and 6B (12 isolates [12%])—accounted for 86 (84%) of these 102 isolates. Seventy four (73%) isolates had the macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype and carried Tn916 transposons (most commonly Tn6002); of these, 73 (99%) contained the erythromycin ribosomal methylase gene [erm(B)], 34 (47%) also carried the macrolide efflux gene [mef(E)], and 41 (55%) belonged to serotype 19F. Of 28 (27%) isolates with the M phenotype, 22 (79%) carried mef(A), including 16 (57%) belonging to serotype 14, and only six (19%) carried Tn916 transposons. Most (84%) isolates which contained mef also contained one of the msr(A) homologues, mel or msr(D); 38 of 40 (95%) isolates with mef(E) (on mega) carried mel, and of 28 (39%) isolates with mef(A)...

Amino acid substitutions in the E2 glycoprotein of Sindbis-like virus XJ-160 confer the ability to undergo heparan sulfate-dependent infection of mouse embryonic fibroblasts

Zhu, Wuyang; Fu, Shihong; He, Ying; Li, Jinping; Liang, Guodong
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 14/09/2010 Português
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We have recently demonstrated an essential role of the domain of 145-150 amino acid in the E2 glycoprotein of Sindbis virus in the interaction with cellular heparan sulfate (HS) and in the infection of mouse embryonic fibroblasts (MEF) cells. In this study, we constructed and characterized the mutants of Sindbis-like virus XJ-160 in which Tyr-146 and/or Asn-149 in the E2 glycoprotein had been substituted with His and Arg, respectively. Unlike parental virus XJ-160, mutants with either or both substitutions were able to infect wild-type mouse embryonic fibroblasts (MEF-wt) or MEF-Epi-/- cells which produce mutant HS. Significantly more infectious particles were released from MEF-wt than from MEF-Epi-/- cells. The mutant virus with both substitutions release was inhibited by pre-incubation of virus with heparin or pre-treatment of BHK-21 cells with HS-degrading enzyme. Both XJ-160 and the mutant viruses retained substantial neurovirulence in suckling mice. Our findings provide further support to the importance of positively charged residues in the HS-binding site of E2 in mediating Sindbis virus infection of MEF cells.

MicroRNA (miRNA)-mediated Interaction between Leukemia/Lymphoma-related Factor (LRF) and Alternative Splicing Factor/Splicing Factor 2 (ASF/SF2) Affects Mouse Embryonic Fibroblast Senescence and Apoptosis*

Verduci, Lorena; Simili, Marcella; Rizzo, Milena; Mercatanti, Alberto; Evangelista, Monica; Mariani, Laura; Rainaldi, Giuseppe; Pitto, Letizia
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
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Leukemia/lymphoma-related factor (LRF) is a transcriptional repressor, which by recruiting histone deacetylases specifically represses p19/ARF expression, thus behaving as an oncogene. Conversely, in mouse embryonic fibroblasts (MEF), LRF inhibition causes aberrant p19ARF up-regulation resulting in proliferative defects and premature senescence. We have recently shown that LRF is controlled by microRNAs. Here we show that LRF acts on MEF proliferation and senescence/apoptosis by repressing miR-28 and miR-505, revealing a regulatory circuit where microRNAs (miRNAs) work both upstream and downstream of LRF. By analyzing miRNA expression profiles of MEF transfected with LRF-specific short interfering RNAs, we found that miR-28 and miR-505 are modulated by LRF. Both miRNAs are predicted to target alternative splicing factor/splicing factor 2 (ASF/SF2), a serine/arginine protein essential for cell viability. In vertebrates, loss or inactivation of ASF/SF2 may result in genomic instability and induce G2 cell cycle arrest and apoptosis. We showed that miR-28 and miR-505 modulate ASF/SF2 by directly binding ASF/SF2 3′-UTR. Decrease in LRF causes a decrease in ASF/SF2, which depends on up-regulation of miR-28 and miR-505. Alteration of each of the members of the LRF/miR-28/miR-505/ASF/SF2 axis affects MEF proliferation and the number of senescent and apoptotic cells. Consistently...

Optimizing a 3D Culture System to Study the Interaction between Epithelial Breast Cancer and Its Surrounding Fibroblasts

Li, Liyuan; Lu, Yi
Fonte: Ivyspring International Publisher Publicador: Ivyspring International Publisher
Tipo: Artigo de Revista Científica
Publicado em 25/08/2011 Português
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Stromal fibroblasts are suggested to be a key determinant in the malignant progression of breast cancer. To find an in vitro culture model that best mimics the in vivo tumor microenvironment so we can study the effects of stromal fibroblasts on breast cancer progression, we evaluated several three-dimensional (3D) co-culture models in order to identify the most suitable culture model for our study. The purpose of our study is to co-culturing malignant mouse breast cancer 4T1 cells and murine embryonic fibroblasts (MEF) to form spheroids with matrigel. We found the best culture model for forming the 4T1 aggregates/spheroids was, in the absence of fibroblast, by growing 4T1 cells in the culture wells precoated with matrigel and in the overlay medium containing 2% matrigel. We chose this model as our standard 3D culture to co-culture 4T1 and MEF cells at different ratios. We found that the amount of MEF in the 4T1/MEF mixture affects the morphology of 4T1/MEF aggregates/spheroids: the higher the ratio of MEF in the mixture, the more ductal structures formed among the aggregates, and the more polarized-like alveolar structures they tended to become. Fibroblasts produced protection for the breast cancer cells in the 3D culture, as aggregates/spheroids formed by breast-cancer cells alone were more sensitive to cytotoxic chemo-agents than aggregates formed by the breast-cancer/fibroblast mixture. These results indicate that the selection of a suitable 3D culture model for a particular research focus may be critical to collecting clinically relevant information about tumor progression that involves interplay between different cell types. This 3D co-culture model demonstrated that tumor-surrounding fibroblasts play important roles in distributing and connecting epithelial breast cancer cells in a tumor microenvironment...

Caffeine Abolishes the Ultraviolet-Induced REV3 Translesion Replication Pathway in Mouse Cells

Takezawa, Jun; Aiba, Naomi; Kajiwara, Kagemasa; Yamada, Kouichi
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 29/11/2011 Português
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When a replicative DNA polymerase stalls upon encountering a photoproduct on the template strand, it is relieved by other low-processivity polymerase(s), which insert nucleotide(s) opposite the lesion. Using an alkaline sucrose density gradient sedimentation technique, we previously classified this process termed UV-induced translesion replication (UV-TLS) into two types. In human cancer cells or xeroderma pigmentosum variant (XP-V) cells, UV-TLS was inhibited by caffeine or proteasome inhibitors. However, in normal human cells, the process was insensitive to these reagents. Reportedly, in yeast or mammalian cells, REV3 protein (a catalytic subunit of DNA polymerase ζ) is predominantly involved in the former type of TLS. Here, we studied UV-TLS in fibroblasts derived from the Rev3-knockout mouse embryo (Rev3KO-MEF). In the wild-type MEF, UV-TLS was slow (similar to that of human cancer cells or XP-V cells), and was abolished by caffeine or MG-262. In 2 cell lines of Rev3KO-MEF (Rev3−/− p53−/−), UV-TLS was not observed. In p53KO-MEF, which is a strict control for Rev3KO-MEF, the UV-TLS response was similar to that of the wild-type. Introduction of the Rev3 expression plasmid into Rev3KO-MEF restored the UV-TLS response in selected stable transformants. In some transformants...

The Effect of Human and Mouse Fibroblast Feeder Cells on Cardiac Differentiation of Human Pluripotent Stem Cells

Pekkanen-Mattila, Mari; Ojala, Marisa; Kerkelä, Erja; Rajala, Kristiina; Skottman, Heli; Aalto-Setälä, Katriina
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
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Mouse embryonic fibroblasts (MEFs) and human foreskin fibroblasts (hFFs) are commonly used as feeder cells to maintain the pluripotent state of stem cells. The aim of the present study was to evaluate the effect of MEF and hFF feeders on the cardiac differentiation. Two human embryonic and two induced pluripotent stem cell lines were cultured on MEF and hFF before cardiac differentiation. The expression of Brachyury T was higher in cell lines cultured on MEF, than if cultured on hFF, suggesting enhanced mesoderm formation. However, significant positive influence of MEF feeders on cardiac differentiation was only seen with one cell line. Further, the ability of hFF to maintain pluripotency of stem cells originally cultured on MEF was quite poor. In conclusion, the cells behaved differently whether cultured on hFF or MEF feeders. However, the influence of the feeder cells on differentiation was less than the difference observed between the cell lines.

Quantitative Analysis of Retromer Complex-Related Genes during Embryo Development in the Mouse

Park, Sang-Je; Huh, Jae-Won; Kim, Young-Hyun; Kim, Ji-Su; Song, Bong-Seok; Lee, Sang-Rae; Kim, Sun-Uk; Kim, Heui-Soo; Imakawa, Kazuhiko; Chang, Kyu-Tae
Fonte: Korean Society for Molecular and Cellular Biology Publicador: Korean Society for Molecular and Cellular Biology
Tipo: Artigo de Revista Científica
Publicado em 31/05/2011 Português
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The retromer complex is a heteropentameric protein unit associated with retrograde transport of cargo proteins from endosomes to the trans-Golgi network. Functional silencing study of the Vps26a gene indicated the important role of the retromer complex during early developmental stages in the mouse. However, individual expression patterns and quantitative analysis of individual members of the retromer complex during the early developmental stages has not been investigated. In this study, we conducted quantitative expression analysis of six retromer complex genes (Vps26a, Vps26b, Vps29, Vps35, Snx1, and Snx2) and one related receptor gene (Ci-mpr) during the eleven embryonic stages with normal MEF (mouse embryonic fibroblast) and Vps26a-/- MEF cells. Remarkably, except for Vps26a (maternal expression pattern), all tested genes showed maternal-zygotic expression patterns. And five genes (Vps26b, Vps29, Vps35, Snx2, and Ci-mpr) showed a pattern of decreased expression in Vps26a-/- MEF cells by comparative analysis between normal MEF and Vps26a-/- MEF cells. However, the Snx1 gene showed a pattern of increased expression in Vps26a-/- MEF cells. From our results, we could assume that retromer complexrelated genes have important roles during oocyte development. However...

The Effect of Fibroblast Co-culture on In Vitro Maturation of Mouse Preantral Follicles

Kim, Chung-Hoon; Cheon, Yong-Pil; Lee, You-Jeong; Lee, Kyung-Hee; Kim, Sung-Hoon; Chae, Hee-Dong; Kang, Byung-Moon
Fonte: Korean Society of Developmental Biology Publicador: Korean Society of Developmental Biology
Tipo: Artigo de Revista Científica
Publicado em /09/2013 Português
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This study was performed to evaluate the effects of fibroblast co-culture on in vitro maturation (IVM) of prepubertal mouse preantral follicles. The intact preantral follicles were obtained from the ovaries of 12-14 day old mice and these were cultured individually in α-minimal essential medium (α-MEM) supplemented with 5% fetal bovine serum (FBS), 100 mIU/Ml recombinant follicle stimulating hormone (rFSH), 1% insulin-transferrin-selenium, 100 μg/ml penicillin and 50 μg/Ml streptomycin as base medium for 12 days. A total of 200 follicles were cultured in base medium co-cultured with mouse embryonic fibroblast (MEF) (MEF group) (n=100) or only base medium as control group (n=100). Survival rate of follicles on day 12 of culture were significantly higher in the MEF group of 90.0%, compared with 77.0% of the control group (p=0.021). Follicle diameters on day 6 and 8 of the culture period were significantly larger in the MEF group than those in the control group (p=0.021, p=0.007, respectively). Estradiol levels in culture media on day 4, 6, 8, 10 and 12 of the culture period were significantly higher in the MEF group (p=0.043, p=0.021, p=0.006, p<0.001 and p=0.008, retrospectively). Our data suggest that MEF cell co-culture on IVM of mouse preantral follicle increases survival rate and promotes follicular growth and steroid production.

Caracterización de modelos celulares con pérdida y ganancia de función de las proteínas TIA1 y TIAR

Sánchez Jiménez, Carmen
Fonte: Universidade Autônoma de Madrid Publicador: Universidade Autônoma de Madrid
Tipo: Tese de Doutorado
Português
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Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 19-05-2014; T-cell intracellular antigen 1 (TIA1) and TIA1 related/like protein (TIAR/TIAL) are two ribonucleoproteins implicated in RNA metabolism at different regulatory layers of gene expression. In the nucleus, they both act as transcriptional and alternative splicing regulators. In the cytoplasm, they are modulators of translation and stability of cellular mRNAs. By its multifunctional display on several gene expression regulatory networks, TIA proteins have a pleiotropic role in the control of cell physiology. In fact, TIA proteins have relevant biological and pathological implications in several cell responses such as cell death/survival, cell proliferation/ growth, inflammation, cell stress, viral infections, tumorigenesis and embryogenesis. The goal of this doctoral thesis has been to study two cell models with loss- and gain-of function of TIA1 and TIAR proteins. Mice lacking either TIA1 or TIAR show high rates of embryonic lethality suggesting a relevant role for these proteins during organismal development. In this work, we approach the transcriptomic and phenotypic characterization of TIA1 or TIAR knocked-out (KO) murine embryonic fibroblast (MEF) derived from the above system. We demonstrate that inactivation of TIA proteins broadly alters gene expression associated with signaling pathways implicated in embryonic pattern formation and organ development. Furthermore...

Influence of electro-heating on the production of whey protein cold-set hydrogels

Pereira, Ricardo; Rodrigues, Rui M.; Ramos, Óscar L.; Malcata, F. X.; Teixeira, J. A.; Vicente, A. A.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 06/11/2014 Português
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Electro-heating has often been claimed to interfere with distribution of molecular secondary structure of whey protein isolate (WPI) networks due to the presence of a moderate electric field (MEF). Recently, cold gelation ability of WPI is also taking interest in protection and delivery of value-added bioactive compounds through micro and nano-association techniques. Hence, the aim of this work is producing cold-set hydrogels from WPI through combined application of an electro-heating treatment followed by cold gelation. Protein dispersions were heated under the absence and presence of MEF at denaturation temperatures (> 80 °C). Divalent iron cation (Fe2+) assisted cold gelation of electro-heated WPI and the effects of MEF on the produced hydrogels were reported and encouraged during this research. Nano-scale phenomena of WPI thermal aggregation as affected by applied MEF were assessed by dynamic light scattering technique. To shed more light on the produced protein hydrogels, samples were investigated by means of transmission electron microscopy and rheology techniques. Results shows that apparent viscosity values and protein aggregation decreased with increasing MEF intensity applied (i.e. treatments at 10 V/cm have determined an average particle sizes below 100 nm). Fe2+ addition resulted in the formation of a network mediated via interactions between cationic agents and WPI soluble aggregates. MEF and cold gelation can induces changes from a nanometer to micrometer range thus offering a great potential to the development of whey protein hydrogels with tailored mechanical and microstructural features Acknowledgments: Ricardo N. Pereira and Oscar L. Ramos gratefully acknowledge their Post-Doctoral grants (SFRH/BPD/81887/2011 and SFRH/BPD/80766/2011...

LMP1 of Epstein-Barr Virus Induces Proliferation of Primary Mouse Embryonic Fibroblasts and Cooperatively Transforms the Cells with a p16-Insensitive CDK4 Oncogene

Yang, Xinhai; Sham, Jonathan S. T.; Ng, M. H.; Tsao, Sai-Wah; Zhang, Dekai; Lowe, Scott W.; Cao, Liang
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2000 Português
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The latent membrane protein LMP1 of Epstein-Barr virus (EBV) is often present in EBV-associated malignancies including nasopharyngeal carcinoma and Hodgkin's lymphoma. Previous work demonstrates that the LMP1 gene of EBV is sufficient to transform certain established rodent fibroblast cell lines and to induce the tumorigenicity of some human epithelial cell lines. In addition, LMP1 plays pleiotropic roles in cell growth arrest, differentiation, and apoptosis, depending on the background of the target cells. To examine the roles of LMP1 in cell proliferation and growth regulation in primary culture cells, we constructed a recombinant retrovirus containing an LMP1 gene. With this retrovirus, LMP1 was shown to stimulate the proliferation of primary mouse embryonic fibroblasts (MEF cells). It has a mitogenic activity for MEF cells, as demonstrated by an immediate induction of cell doubling time. In addition, it significantly extends the passage number of MEF cells to more than 30 after retroviral infection, compared with less than 5 for uninfected MEF cells. Furthermore, LMP1 cooperates with a p16-insensitive CDK4R24C oncogene in transforming MEF cells. Our results provide the first evidence of the abilities of the LMP1 gene, acting alone...

On the Modeling of Elastic and Inelastic, Critical- and Post-Buckling Behavior of Slender Columns and Bracing Members

Krishnan, Swaminathan
Fonte: Earthquake Engineering Research Laboratory Publicador: Earthquake Engineering Research Laboratory
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em 04/05/2009 Português
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Analyzing tall braced frame buildings with thousands of degrees of freedom in three dimensions subject to strong earthquake ground motion requires an efficient brace element that can capture the overall features of its elastic and inelastic response under axial cyclic loading without unduly heavy discretization. This report details the theory of a modified elastofiber (MEF) element developed to model braces and buckling-sensitive slender columns in such structures. The MEF element consists of three fiber segments, two at the member ends and one at mid-span, with two elastic segments sandwiched in between. The segments are demarcated by two exterior nodes and four interior nodes. The fiber segments are divided into 20 fibers in the crosssection that run the length of the segment. The fibers exhibit nonlinear axial stress-strain behavior akin to that observed in a standard tension test in the laboratory, with a linear elastic portion, a yield plateau, and a strain hardening portion consisting of a segment of an ellipse. All the control points on the stress-strain law are user-defined. The elastic buckling of a member is tracked by updating both exterior and interior nodal coordinates at each iteration of a time step, and checking force equilibrium in the updated configuration. Inelastic post-buckling response is captured by fiber yielding in the nonlinear segments. A user-defined probability distribution for the fracture strain of a fiber in a nonlinear segment enables the modeling of premature fracture...