Spelling suggestions: "subject:"ssa"" "subject:"essa""
31 |
Measuring the effect of cathodic protection on the performance of thermally sprayed aluminium coatings at elevated temperature / Avaliação do efeito da proteção catódica no desempenho do revestimento de alumínio pulverizado termicamente submetido a altas temperaturasCé, Nataly Araújo January 2017 (has links)
Alumínio Pulverizado Termicamente (TSA) é amplamente utilizado em instalações offshore como revestimento de ânodo de sacrifício em tubulações de aço carbono. O transporte e a instalação desses componentes podem levar a pequenos danos no revestimento, o que pode expor a superfície do aço à água do mar. Sabe-se que o depósito calcário é formado na superfície do aço polarizado catodicamente. Assim, esta pesquisa avaliou o TSA aplicado por sistema de pulverização de arco duplo (TWAS) no aço ao carbono S355J2 + N quando ocorrem danos (holidays) para estudar a formação de depósitos calcários no aço e adquirir dados sobre o desempenho do TSA sob altas temperaturas. A aplicação de diferentes condições também foi considerada: presença de selantes; liga do revestimento (99,5% de Al e Al-5% de Mg) e condições enterradas/não enterradas. Dois tipos de experimentos foram realizados: i) testes em potencial livre sob temperaturas constantes (30, 60 e 90°C) e diferentes tamanhos de holidays (expondo 5, 10 e 20% da superfície do aço) e ii) testes sob gradient térmico onde óleo a ~125°C foi adicionado em uma torre polimérica e água externa a ~10°C ficou em contato com a superfície das amostras (tanto potencial livre como polarização de -950 mVAg/AgCl foram aplicados). Análises incluíram inspeção visual, microscópio eletrônico de varredura e difração de Raio-X. A partir dos testes em temperaturas constante, o TSA atingiu um bom potencial de proteção (-800 a -900 mVAg/AgCl) e pouca diferença nos resultados devido à diferença na composição doTSA e no tamanho do holiday foi observada. As taxas de corrosão foram mantidas entre 0,02 e 0,01 mm/ano. No ensaio sob gradiente térmico e potencial livre, a perda de revestimento e as taxas de corrosão foram de 0,4 a 0,002 mm/ano. Além disso, o potencial alcançado foi de uma faixa menor do que a obtida anteriormente (-745 a -835 mVAg/AgCl). No entanto, quando o TSA foi combinado com proteção catódica externa e gradiente térmico, a espessura do TSA foi satisfatório e as taxas de corrosão obtidas foram inferiores a 0,076 mm/ano. O depósito calcário formado no holiday protegeu o aço contra a corrosão e seu mecanismo de crescimento baseado nesta pesquisa foi construído. / Thermally Sprayed Aluminium (TSA) is widely used in offshore facilities as sacrificial anode coating for carbon-steel risers and pipelines. Transportation and installation of those components can lead to small damages in the coating, which can expose the steel surface to the seawater. It is known that calcareous deposit is formed on the cathodically polarised steel surface. Thus, this research evaluated the TSA applied by twin wire arc spray system (TWAS) on S355J2+N carbon-steel when damage (holidays) is present in order to study the calcareous deposit formation on steel and acquire data regarding the TSA performance at high temperatures. Application of different conditions was also considered: presence of sealing; coating alloy (99.5%Al and Al-5%Mg) and buried/unburied conditions. Generally, two types of experiment were conducted – i) tests at free potential at steady temperatures (30, 60 and 90°C) and different holiday sizes (exposing 5, 10 and 20% of the steel surface) and ii) tests under thermal gradient where oil at ~125°C was added in polymeric tower and external water at ~10°C was in contact with the samples surface (both free potential and polarisation of -950 mVAg/AgCl were applied). Methodology of analyses included visual inspection, scanning electron microscope and X-ray Diffraction. From the tests at steady temperatures, the TSA reached a very good protective potential (-800 to -900 mVAg/AgCl) and little difference in results due to difference in TSA composition and holiday size was observed. Corrosion rates were kept between 0.02 and 0.01 mm/year. From the thermal gradient test under free potential, the coating loss and corrosion rates were 0.4 to 0.002 mm/year. Also, the potential achieved was in a lower range than previously obtained (-745 to -835 mVAg/AgCl). However, when TSA was combined with external cathodic protection and thermal gradient, the thickness of the TSA was satisfactory and corrosion rates obtained were below 0.076 mm/year. The calcareous deposit formed within the holiday protected the steel substrate against corrosion and its growth mechanism based in this research was built.
|
32 |
Papel das histonas deacetilases na amígdala basolateral na modulação da memória emocionalValiati, Fernanda Endler January 2015 (has links)
Introdução: A formação da memória envolve mudanças na expressão de genes neuronais. Remodelações epigenéticas da cromatina e modificações pós-traducionais reversíveis no DNA ou nas proteínas histonas representam mecanismos centrais na regulação da expressão gênica durante o desenvolvimento do cérebro e a aprendizagem inicial ou recuperação da memória. Desequilíbrios nos níveis de acetilação de histonas estão associados à uma ampla variedade de desordens cerebrais. Histonas deacetilases (HDACs) desempenham um papel fundamental na homeostase da acetilação de histonas e na regulação de atividades celulares fundamentais como a transcrição, tornando-as um foco de estudo. Evidências mostram que a administração de inibidores de histonas deacetilases (HDACis) restauram a memória associada à regulação da expressão gênica e melhora a memória em ratos. Estudos em modelos animais têm mostrado que a formação da memória envolve uma série de alterações bioquímicas em várias áreas do sistema nervoso central, entre as quais se destacam o hipocampo e a amígdala basolateral (BLA). Neste contexto, fármacos experimentais, como a tricostatina A (TSA), que atuam sobre mecanismos epigenéticos, têm sido recentemente propostos como potenciais terapias para o tratamento de disfunção cognitiva e memória associados a doenças neurológicas e psiquiátricas. Objetivo: Neste trabalho objetivamos compreender e elucidar o papel da acetilação de histonas em processos envolvidos na modulação da memória utilizando o fármaco TSA e se baseia na hipótese de que a atividade de HDACs é essencial para a modulação das respostas de aprendizado na tarefa de esquiva inibitória (IA). Métodos: Ratos Wistar foram canulados bilateralmente na amígdala. Os efeitos das micro-infusões intra-amigdalares de TSA foram observados na consolidação e na extinção da memória após o treino na tarefa de esquiva inibitória e nos níveis do fator neurotrófico derivado do cérebro (BDNF) na BLA e no hipocampo referentes à consolidação da memória. Resultados: Os resultados demonstraram que a infusão intra-amigdalar de TSA 1.5 h, 3 h e 6 h após o treino na tarefa de esquiva inibitória resulta na melhora da memória de longa duração (LTM). TSA acelerou a extinção da memória quando infundido imediatamente pós-teste. Além disso, aumentou os níveis de BDNF no hipocampo. Conclusão: Estes resultados indicam que eventos epigenéticos possuem um papel importante no aprendizado e na memória através da atividade de HDACs. / Introduction: Memory formation involves changes in the expression of neuronal genes. Epigenetic remodeling of chromatin and reversible post-translational modifications in the DNA or in the histone proteins represent central mechanisms in the regulation of gene expression during brain development and early learning or memory retrieval. Imbalances in the levels of histone acetylation are associated with a wide variety of brain disorders. Histone deacetylases (HDACs) play a key role in homeostasis of histone acetylation and regulation of fundamental cellular activities, such as transcription, making them a focus of study. Evidences shows that the administration of histone deacetylases inhibitors (HDACis) restore the memory associated with the regulation of gene expression and improves memory in rats. Studies in animal models have shown that memory formation involves a series of biochemical changes in several areas of the central nervous system, which the hippocampus and basolateral amygdala (BLA) are the most highlighted. In this context, experimental drugs, such as trichostatin A (TSA), that act on epigenetic mechanisms, have recently been proposed as potential therapies for the treatment of memory and cognitive dysfunction associated with psychiatric and neurological disorders. Objective: In this work we aimed to understand and elucidate the role of histone acetylation in processes involved in memory modulation using the drug TSA and is based on the hypothesis that HDACs activity is essential for the modulation of learning answers in the inhibitory avoidance (IA) task. Methods: Wistar rats were cannulated bilaterally in the amygdala. The effects of TSA micro-infusions into the BLA were observed in the consolidation and extinction of memory after training in the inhibitory avoidance task and the levels of brain-derived neurotrophic factor (BDNF) in the BLA and hippocampus related to memory consolidation. Results: The results demonstrated that the TSA infusion into BLA 1.5 h , 3 h and 6 h posttraining in the inhibitory avoidance task results in improved long-term memory (LTM). TSA accelerated the extinction of memory when infused immediately post-test. In addition, increased levels of BDNF in the hippocampus. Conclusion: These results indicate that epigenetic events play an important role in learning and memory by HDAC activity.
|
33 |
Corrosion resistance study of AA2524 anodized in sulphuric-tartaric acid and sealed with hybrid coatings. / Estudo da resistência à corrosão da liga AA2524 anodizada em solução sulfúrico-tartárico e selada por um revestimento híbrido.Hellen Costerano Guadagnin 02 May 2017 (has links)
Aluminium alloys are widely used in the aerospace industry due to their lightweight and high specific strength. However, these alloys are particularly sensitive to localized corrosion in chloride environments and need to be protected by a robust system. One of the protection methodologies consists in anodizing. The produced layer increases the corrosion resistance and also serves as anchoring site for organic coatings application. Chromium-based anodizing has been usually employed, nevertheless, as chromate compounds are toxic for health and the environment, chromium-based surface treatments will be prohibited in the aerospace industry in a near future. Tartaric-sulphuric acid (TSA) anodizing is a promising environment compliant alternative, which is already being used at industrial level with appropriate corrosion protection and paint adhesion properties. This study aims at proposing a hybrid sol-gel treatment after TSA anodizing of AA2524 specimens in order to improve the corrosion resistance of the anodized layer while maintaining its compatibility with organic coatings. For this, anodic aluminium oxides (AAO) were produced at different anodizing voltages and protected by dip-coating with a hybrid sol-gel layer obtained from a tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) hydrolysis solution with high water content. Corrosion resistance evaluation was carried out by means of electrochemical impedance spectroscopy (EIS) in NaCl 0.1 mol L-1 and salt-spray chamber exposure (ASTM B117-11 standard). The morphology of the anodic porous layer was investigated by means of FE-SEM, whereas glow discharge optical emission spectroscopy (GDOES) was employed to evaluate the distribution of the sol-gel layer within the porous AAO. FE-SEM characterization confirmed that the layer properties (pore distribution, porosity and thickness) were strongly dependent on the anodizing conditions, whereas GDOES depth profile showed penetration of the hybrid coating within the pores of the anodized layer. The two characterization techniques showed inefficient surface sol-gel coverage for the samples anodized at higher voltage, likely due to insufficient sol-gel deposition. The results of the EIS characterization tests up to 1008 h (42 days) showed that, irrespectively to the anodizing voltage, the hybrid sol-gel protected AAO was stable with only slight evolution of the diagrams with immersion time. Moreover, the hybrid coating protected samples presented higher low frequency impedance modulus than hydrothermally sealed (HTSed) reference TSA anodized samples, which was confirmed by electrical equivalent circuit (EEC) fitting of the EIS data. EEC fitting also revealed that the resistance of the pores to electrolyte penetration was increased by the application of the sol-gel coating when compared to the resistance of the HTSed reference samples and indicated better anticorrosion performance for the sample anodized at 16 V. These results were confirmed by the salt-spray tests. Investigation on the ageing of the hybrid sol-gel hydrolysis solution showed that its viscosity hardly changed up to two weeks of test and that hybrid coatings applied from these solutions were stable and afforded good corrosion protection to the TSA anodized substrate, an improvement of the anticorrosion properties of the hybrid coating was verified for an ageing time of 168 h. Preliminary tests performed with a solvent-free organic coating (epoxy) indicated good compatibility with the hybrid TEOS-GPTMS coating characterized by very high impedance and good stability upon exposure to the salt-spray chamber. / Ligas de alumínio são muito utilizadas na indústria aeronáutica por serem materiais leves e altamente resistentes. Porém, essas ligas são particularmente sensíveis à corrosão localizada em meios que contêm cloretos, e precisam de sistemas robustos de proteção. Uma das metodologias de proteção consiste em anodização. A camada produzida aumenta a resistência à corrosão e também serve como sítio de ancoragem para aplicação de revestimentos orgânicos. A anodização crômica tem sido usualmente empregada na indústria aeronáutica. No entanto, como compostos contendo íons cromato são tóxicos para a saúde e para o meio-ambiente, tratamentos de superfície à base de cromo serão proibidos na indústria espacial em um futuro próximo. Anodização em banho de ácido sulfúrico-tartárico (TSA) é uma alternativa promissora e ambientalmente compatível, a qual já está sendo usada industrialmente com apropriada proteção à corrosão e adesão para pintura. Este estudo tem como objetivo propor um tratamento utilizando um revestimento híbrido sol-gel para melhorar a resistência à corrosão da liga AA2524 anodizada em TSA e que mantenha sua compatibilidade com revestimentos orgânicos. Para isso, camadas anodizadas de alumínio (CAA) foram produzidas em diferentes voltagens e protegidas por camada de híbrido sol-gel obtida pela hidrólise de tetraetilortosilano (TEOS) e glicidóxipropiltrimetóxisilano (GPTMS) em solução com alto teor de água e aplicada pela técnica de dip-coating. A avaliação da resistência à corrosão foi realizada através de espectroscopia de impedância eletroquímica (EIS) em NaCl 0,1 mol.L-1 e por exposição à câmara de névoa salina (norma ASTM B117-11). A morfologia da camada porosa foi investigada por MEV e a espectroscopia de emissão óptica por descarga luminescente (GDOES) foi empregada para avaliar a distribuição do híbrido sol-gel no interior dos poros da camada porosa. As caracterizações por MEV confirmaram que as propriedades da camada (distribuição dos poros, porosidade e espessura) são fortemente dependentes das condições de anodização, e a composição em profundidade obtida por GDOES mostrou que o revestimento híbrido penetrou nos poros da camada anodizada. As duas técnicas de caracterização mostraram uma cobertura ineficiente da camada sol-gel para as amostras anodizadas nas voltagens mais elevadas, provavelmente devido à deposição insuficiente do híbrido. Os testes de EIS com duração de até 1008 h (42 dias) mostraram que, independentemente da voltagem de anodização empregada, a camada anódica coberta com sol-gel ficou estável ocorrendo apenas pequenas evoluções dos diagramas com o tempo de imersão. Além do mais, as amostras protegidas com o revestimento híbrido apresentaram maiores valores de módulo de impedância em baixa frequência do que as amostras anodizadas em TSA e hidrotermicamente seladas (HTsed) usadas como referências. Essa tendência foi confirmada pelo ajuste com circuitos elétricos equivalentes (EEC) dos resultados de EIS que também mostrou que a aplicação do sol-gel híbrido torna mais difícil a penetração do eletrólito agressivo nos poros da camada anodizada quando comparada com as amostras HTSed, e indicou melhor desempenho anticorrosivo para a amostra anodizada em 16 V. Esses resultados foram confirmados pelos testes de névoa salina. A investigação do envelhecimento da solução de sol-gel mostrou pouca mudança na viscosidade da solução de hidrólise em duas semanas de testes e que os revestimentos híbridos aplicados a partir dessas soluções foram estáveis e promoveram boa proteção à corrosão para as amostras anodizadas em TSA, com melhora das propriedades anticorrosivas após 168 h de envelhecimento. Testes preliminares realizados com revestimento orgânico livre de solvente (epóxi) indicaram boa compatibilidade deste com o revestimento híbrido TEOS-GPTMS. O revestimento epóxi propiciou valores de módulo de impedância elevados e estáveis e também boa estabilidade após exposição à câmara de névoa salina quando aplicado sobre o revestimento híbrido aplicado sobre a liga 2524.
|
34 |
Identification des besoins familiaux et évaluation d'un programme de répit : intervention appliquée aux parents d'enfants avec Troubles du spectre de l'autisme / Identification of family needs and evaluation of a respite program : applied intervention for parents of children with Autism spectrum disordersDell'Armi, Mélina 07 September 2016 (has links)
De nombreuses études ont montré que les Troubles du Spectre de l’Autisme ont un impact significatif surla vie quotidienne de l’enfant et de son entourage, plus particulièrement de sa famille et ses parents. Lesrecherches dans ce domaine se sont donc de plus en plus centrées sur la famille, permettant l’apport deressources, de supports ou de services. En effet, leur rôle dans l’accompagnement de l’enfant est essentiel,et un soutien adapté aux parents c’est également un soutien indirect à l’enfant. Cependant, la disponibilitédes services à destination des parents reste insuffisante, et ces derniers sont très peu associés à la miseen place d’interventions correspondant à leurs besoins, alors qu’ils sont les premiers utilisateurs desdispositifs proposés.L’étude 1 propose la traduction et la validation du Family Needs Questionnaire (renommé Questionnairedes Besoins Familiaux – QBF). Les résultats montrent de bonnes qualités psychométriques, ce quiindique que cet instrument peut être utilisé pour évaluer les besoins des parents d’enfants avec TSA enpopulation française. L’objectif de l’étude 2 est d’explorer les besoins des mères d’enfants avec TSA, enutilisant deux méthodes d’évaluation : une évaluation quantitative grâce à des questionnairesd’évaluation des besoins, dont le QBF, et une évaluation qualitative par des entretiens et une questionouverte. Concernant l’étude 3, il s’agit de comparer les besoins des parents d’enfants avec TSA et desparents d’enfants dysphasiques. Les résultats de ces études montrent que les besoins principaux desparents d’enfants avec TSA sont des besoins centrés sur l’école, centrés sur la vie sociale de leur enfant, etdes besoins en temps de répit. Ces résultats sont retrouvés par l’utilisation des deux méthodesd’évaluation, et ne sont pas retrouvés chez les parents d’enfants dysphasiques, ce qui indique que ce sontdes besoins spécifiques aux parents d’enfants avec TSA. Enfin, l’étude 4 présente une étude longitudinalequi évalue l’impact d’un programme d’interventions à domicile permettant un temps de répit aux parentsd’enfants avec TSA. Aucun impact n’a été trouvé sur les variables évaluant la qualité de vie, bien que lasatisfaction des parents vis à vis de ce programme ait été élevée. / Many studies have highlighted that Autism Spectrum Disorders (ASD) have a significant impact on theindividual’s daily life, and his/her relatives (i.e. family and parents). Research in this area has thereforeincreasingly focused on the family, providing resources, support and services. Indeed, their role in thechild’s support is of prime importance, and appropriate support for carers is also indirect support for thechild. While parents are the primary users of the proposed devices, availability of such services stillremain inadequate, and do not play an important role in the implementation of interventionsStudy 1 aims to translate and validate a French version of the Family Needs Questionnaire (FNQ). Theresults have demonstrated good psychometric validity, suggesting that this instrument is adequate toevaluate family needs in a sample of French parents of children with ASD. Study 2, assesses the needs ofmothers of children with ASD, using the FNG-Fr and the Family Needs Survey. Qualitative measures suchas open questions and semi-structured interviews were also used. Study 3 focuses on evaluation of thefamily needs by comparing parents of children with ASD and parents of children with Specific LanguageImpairments (SLI). School-centered needs, needs for child’s social life and respite time needs were ratedas the most unmet needs by parents of children with ASD. Findings from semi-structured interviews andopen question have also highlight such needs that were significantly different compared to those ofparents of with SLI, suggesting specific needs for parents of children with ASD. And study 4 was based ona longitudinal design for evaluating the impact of an at-home intervention program, allowing a respitetime for the families. While parental satisfaction was high, no impact on variables assessing parents’quality of life was found.
|
35 |
Traitement des visages par les jeunes enfants avec un TSA : études en suivi du regard / Face processing in young children with ASD : an eye-tracking perspectiveGuillon, Quentin 18 November 2014 (has links)
De par la richesse et la nature des informations qu’il véhicule, le visage joue un rôle essentiel dans les interactions sociales. Les difficultés que manifestent dès le plus jeune âge les personnes présentant un Trouble du Spectre de l’Autisme (TSA) sur le plan de l’interaction sociale ont conduit à s’intéresser aux modalités de traitement du visage dans cette population. Les travaux de cette thèse ont pour but d’explorer le traitement du visage chez les jeunes enfants avec un TSA, âgés de 24 à 60 mois, au moyen de la technique de suivi du regard. Dans la première étude, nous montrons que les jeunes enfants avec un TSA, comme les enfants typiques, sont sensibles à la visagéité d’un objet, ce qui suggère un traitement de la configuration de premier ordre. Ce résultat suggère que la nature des représentations faciales dans les TSA n’est pas qualitativement différente de celle des personnes typiques. Dans la seconde étude, nous testons la présence d’un biais du regard vers l’hémichamp visuel gauche en réponse à un visage présenté en vision centrale. Les résultats de cette étude indiquent que les jeunes enfants avec un TSA ne présentent pas ce biais du regard, ce qui pourrait refléter une altération de la dominance hémisphérique droite pour le traitement du visage dans les TSA. Enfin, dans la troisième étude, l’analyse du parcours visuel des jeunes enfants avec un TSA sur les visages révèle une exploration atypique concentrée au niveau de la région des yeux. Dans l’ensemble, ces études suggèrent que même si les enfants avec un TSA traitent les visages à partir de leur configuration, la manière d’y parvenir pourrait être différente. Des études futures devront spécifier les mécanismes du traitement configural du visage dans les TSA. / Faces are important for social interactions as they convey important information about social environment. Impairment in social interactions is one of the core symptoms of Autism Spectrum Disorders (ASD) and has been related to atypical face processing. Here, we investigated face processing in preschool children with ASD using eye-tracking methodology. In the first study, we showed that young children with ASD, just like typically developing children are sensitive to face-like objects suggesting that processing first order configuration is intact in ASD. According to these results, the nature of facial representation might be qualitatively similar between groups. In the second study, we tested the presence of a left gaze bias in response to faces presented at central vision. A lack of left gaze bias was found in young children with ASD, reflecting atypical right hemispheric lateralization for face processing. Finally, the third study analyzed the visual scanning of static faces and showed an abnormal exploration pattern limited to the eyes. Overall, these studies argue for the presence of configural face processing in preschoolers with ASD despite differences in strategy from typically developing children. Futures studies will have to specify the mechanisms underlying atypical configural face processing in ASD.
|
36 |
Vlivy cestovního ruchu na národní hospodářství ve srovnání Česká republika ? ChorvatskoStraková, Barbora January 2008 (has links)
Tato diplomová práce se především zabývá vztahem národního hospodářství a cestovního ruchu, jejich vzájemného vymezení a působení. Velký prostor je také věnován satelitnímu účtu cestovního ruchu, který slouží jako nástroj ke statistickému zachycení těchto vlivů. Toto téma je dále pak z praktického hlediska znázorněno na dvou ukázkových zemích, na České republice a Chorvatsku. Po uvedení do problematiky, která je obsahem první kapitoly, je v druhé kapitole nastíněn vývoj cestovního ruchu ve světě a jeho pohled do budoucnosti. Třetí kapitola rozebírá satelitní účet cestovního ruchu, jeho metodologii, tvorbu, aplikaci a výsledky v obou srovnávaných zemích, a to jak z pohledu národních tak mezinárodních statistik. Ve čtvrté kapitole jsou samostatně analyzovány jednotlivé vlivy cestovního ruchu na národní hospodářství s konkrétní ukázkou v obou výše zmíněných zemích. Poslední kapitola obsahuje srovnání České republiky a Chorvatska dle mezinárodní statistik.
|
37 |
Analýza složené soustavy s různým podílem plniva / Analysis of composite system with different filler ratioMydlář, Marek January 2009 (has links)
This master’s thesis applies dielectric relaxation spectroscopy to analyse impact of climatic changes on dielectric properties of composite material samples (TSA 220S varnish combined with 60.030 mica). Experiments aim to analyse effect of mica composite mass ratio (0, 4, 8 and 16 % of mica), relative humidity (0, 33, 55, 65, 75 and 95 %) and temperature (23, 30, 40 and 50 C) on complex permitivity as a function of frequency.
|
38 |
Transcriptional Silencing of the TMSI/ASC Tumour Suppressor Gene by an Epigenetic Mechanism in Hepatocellular Carcinoma CellsZhang, C., Li, H., Zhou, G., Zhang, Q., Zhang, T., Li, J., Zhang, J., Hou, J., Liew, C. T., Yin, D. 01 June 2007 (has links)
DNA methylation and histone modifications have emerged as key mechanisms in transcriptional regulation. The target of methylation-induced silencing 1 (TMS1) is a bipartite protein. Recent studies have indicated that methylation-associated silencing of TMS1 occurs in many cancers. However, whether and how TMS1 is regulated by epigenetic mechanisms in cancers remains unknown. In this study we showed that methylation of the TMS1 promoter occurred in five of six hepatocellular carcinoma (HCC) cell lines. TMS1 expression was reduced in four HCC cell lines and correlated with methylation status. Furthermore, the TMS1 promoter was completely methylated and mRNA expression was undetectable. TMS1 expression could be restored by 5-aza-2′-deoxycitidine (5-Aza-dC) (a DNA methyltransferase inhibitor) or trichostatin A (TSA) (a histone deacetylase inhibitor) alone and the promoter methylation. was partially reversible. TSA was more efficient than 5-Aza-dC in inducing TMS1 expression, and the combination of 5-Aza-dC and TSA resulted in markedly synergistic reactivation of the gene and completely reversed promoter methylation. Interestingly, TMS1 promoter methylation-associated gene silencing was accompanied by histone H3 Lysine 9 (H3K9) hypoacetylation and trimethylation. 5-Aza-dC and/or TSA also had some effect on conversion of methylated to acetylated H3K9 in restoring TMS1. This conversion was dynamic at the TMS1 promoter and a decrease in H3K9 trimethylation preceded an increase in H3K9 acetylation after 5-Aza-dC and/or TSA treatment. Our results thus suggest that epigenetic inactivation of TMS1 expression is regulated by promoter hypermethylation and H3K9 modifications in a coordinated way.
|
39 |
Histone Deacetylase Inhibitors Trichostatin A (tsa) And Sulforaphane (sfn) Modulate Vitamin D Responsive Cyp24 Gene Expression in 3t3-l1 PreadipocytesAhn, Eunjee 01 January 2013 (has links) (PDF)
Vitamin D plays an important role in preserving healthy bones, and has additional roles in the body, including modulation of cell growth, differentiation, neuromuscular and immune function, and anti-inflammatory function. The vitamin D receptor (VDR) is a member of the nuclear hormone receptor superfamily and regulates transcription of vitamin D-dependent target genes, such as those for key proteins involved in calcium and phosphorus absorption and bone development. Histone acetylation weakens the association of histones with DNA, and increases the accessibility of transcriptional regulatory proteins to chromatin templates, thereby increasing transcriptional activity of gene expression. Histone deacetylases remove the acetyl groups and condense chromatin structure, thereby preventing transcription. TSA is a potent histone deacetylase inhibitor and can significantly enhance gene expression. Bioactive food component, sulforaphane (SFN) is found in cruciferous vegetables and is known to be a histone deacetylase inhibitor, leading to transcriptional activation of gene expression. The objective of this study is to demonstrate that the bioactive food components modulate vitamin D action in adipocytes. To investigate the effects of TSA and SFN on vitamin D response, 3T3L1 mouse preadipocytes were treated with the combination of various concentrations of 1,25(OH)2 vitamin D, TSA, and SFN. Upon harvesting cells, the amounts of 24-hydroxylase mRNA, marker of vitamin D response, were measured by semiquantitative reverse transcriptase-PCR analysis. The results showed that the cells treated with 1μM TSA increased 1,25(OH)2 vitamin D-induced CYP24 mRNA level nearly 3.5-fold (p < 0.05) at 1nM 1,25(OH)2 vitamin D and nearly 2.5-fold (p < 0.05) in 10 nM 1,25(OH)2 vitamin D, and the cells treated with 5μM SFN increased 1,25(OH)2 vitamin D-induced CYP24 mRNA level nearly 1.4-fold at 1nM 1,25(OH)2 vitamin D and nearly 1.2-fold at 10 nM 1,25(OH)2 vitamin D.
|
40 |
Galactosidase-catalyzed fluorescence amplification method (GAFAM): sensitive fluorescent immunohistochemistry using novel fluorogenic β-galactosidase substrates and its application in multiplex immunostaining / ガラクトシダーゼ触媒蛍光増幅法(GAFAM):新規の蛍光発生ベータガラクトシダーゼ基質を利用した高感度蛍光免疫組織化学とそのマルチプレックス免疫染色法への応用Hirata, Masahiro 23 May 2023 (has links)
京都大学 / 新制・論文博士 / 博士(人間健康科学) / 乙第13562号 / 論人健博第12号 / 新制||人健||8(附属図書館) / (主査)教授 高桑 徹也, 教授 藤井 康友, 教授 長尾 美紀 / 学位規則第4条第2項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM
|
Page generated in 0.0434 seconds