216,937 research outputs found
The granulocytic inducer C/EBPalpha inactivates the myeloid master regulator PU.1
No full textVerschiedene Transkriptionsfaktoren spielen eine Rolle in der Entwicklung myeloischer Zellen. PU.1, ein Transkriptionsfaktor aus der ETS-Familie, ist sowohl für die Entwicklung lymphatischer als auch für die Entwicklung myeloischer Zellen von Bedeutung. Der Transkriptions
faktor C/EBPalpha, ein an den CCAAT-Enhancer bindendes Protein, ist hingegen wesentlich verantwortlich für die Entwicklung von Granulozyten. Wir stellen hier den ersten Nachweis dafür vor, dass C/EBPalpha die Funktion von PU.1 blockiert. PU.1 und C/EBPalpha können einander binden und sind in myeloischen Zellen kolokalisiert. Wenn C/EBPalpha PU.1 bindet, kann PU.1 einen minimalen Promotor mit Bindungsstelle für PU.1 nicht mehr aktivieren. Wir zeigen, dass der Leuzin-Zipper in der DNA-bindenden Domäne von C/EBPalpha mit der beta3/beta4-Region in der DNA-bindenden Domäne von PU.1 interagieren kann. Dadurch wird der Koaktivator von PU.1, c-jun, aus seiner Bindung mit PU.1 verdrängt. C/EBPalpha hemmt PU.1 nicht, indem es Korepressoren rekrutiert. Vielmehr vermindert C/EBPalpha die Expression von PU.1 in U-937-Zellen mit induzierbarem C/EBPalpha, indem es den autoregulatorischen Effekt PU.1 auf den PU.1-Promotor hemmt.
Ausserdem blockiert C/EBPalpha die durch PU.1 bedingte Entwicklung dendritischer Zellen aus CD34+ menschlichen Nabel blutzellen. Diese funktionelle Blockade von PU.1 durch C/EBPalpha könnte einer der Mechanismen sein, mit denen C/EBPalpha den durch PU.1 determinierten Weg der Zelldifferenzierung hemmt und sich Zellen unter dem Einfluss von C/EBPalpha zu Granulozyten entwickeln.Several transcription factors have been shown to play a role in myelopoiesis. PU.1, an ets-family transcription factor, is required for the development of both myeloid and lymphoid lineages while the transcription factor CCAAT/enhancer binding protein family member C/EBPalpha is essential for granulocytic development. We present here the first evidence that C/EBPalpha blocks the function of PU.1. PU.1 and C/EBPalpha interact physically and co-localize in myeloid cells. As a consequence of this interaction C/EBPalpha can inhibit the function of PU.1 to activate a minimal promoter containing only PU.1 DNA binding sites. We further demonstrate that the leucine zipper in the DNA binding domain of C/EBPalpha interacts with the beta3/beta4 region in the DNA binding domain of PU.1, and as a result displaces the PU.1 co-activator c-Jun. Finally, C/EBPalpha blocks PU.1 induced dendritic cell development from CD34+ human cord blood cells. The functional blocking of PU.1 by C/EBPalpha could be the mechanism by which C/EBPalpha inhibits the cell fates specified by PU.1, and directs cell development to the granulocytic lineage
Differentiation of the mononuclear phagocyte system during mouse embryogenesis:the role of transcription factor PU.1
No full textDuring mouse embryogenesis, macrophage-like cells arise first in the yolk sac and are produced subsequently in the liver. The onset of liver hematopoiesis is associated with the transition from primitive to definitive erythrocyte production. This report addresses the hypothesis that a similar transition in phenotype occurs in myelopoiesis. We have used whole mount in situ hybridization to detect macrophage-specific genes expressed during mouse development. The mouse c-fms mRNA, encoding the receptor for macrophage colony-stimulating factor (CSF-1), was expressed on phagocytic cells in the yolk sac and throughout the embryo before the onset of liver hematopoiesis. Similar cells were detected using the mannose receptor, the complement receptor (CR3), or the Microphthalmia transcription factor (MITF) as mRNA markers. By contrast, other markers including the F4/80 antigen, the macrophage scavenger receptor, the S-100 proteins, S100A8 and S100A9, and the secretory product lysozyme appeared later in development and appeared restricted to only a subset of c-fms-positive cells. Two-color immunolabeling on disaggregated cells confirmed that CR3 and c-fms proteins are expressed on the same cells. Among the genes appearing later in development was the macrophage-restricted transcription factor, PU.1, which has been shown to be required for normal adult myelopoiesis. Mice with null mutations in PU.1 had normal numbers of c-fms-positive phagocytes at 11.5dpc. PU.1(-/-) embryonic stem cells were able to give rise to macrophage-like cells after cultivation in vitro. The results support previous evidence that yolk sac-derived fetal phagocytes are functionally distinct from those arising in the liver and develop via a different pathway
PU-NA-BERT
No full textWe used Electronic medical records from public use datasets provided by Yidu Cloud to obtain the distant dataset by dista。nt supervision. For the obtained distant dataset, to enhance the reliability of the dataset, we used PU learning for denoising to reduce the negative impact of incorrectly labelled negative samples or unlabeled samples on the model. Finally, cancer information extraction was performed using negative sampling and pre-trained modelsWe used Electronic medical records from public use datasets provided by Yidu Cloud to obtain the distant dataset by distant supervision. For the obtained distant dataset, to enhance the reliability of the dataset, we used PU learning for denoising to reduce the negative impact of incorrectly labelled negative samples or unlabeled samples on the model. Finally, cancer information extraction was performed using negative sampling and pre-trained models</p
The T-cell oncogene Tal2 is a Target of PU.1 and upregulated during osteoclastogenesis
No full textTranscription factors play a crucial role in regulating differentiation processes during human life and are important in disease. The basic helix-loop-helix transcription factors Tal1 and Lyl1 play a major role in the regulation of gene expression in the hematopoietic system and are involved in human leukemia. Tal2, which belongs to the same family of transcription factors as Tal1 and Lyl1, is also involved in human leukaemia. However, little is known regarding the expression and regulation of Tal2 in hematopoietic cells. Here we show that Tal2 is expressed in hematopoietic cells of the myeloid lineage. Interestingly, we found that usage of the Tal2 promoter is different in human and mouse cells. Two promoters, hP1 and hP2 drive Tal2 expression in human erythroleukemia K562 cells, however in mouse RAW cells only the mP1 promoter is used. Furthermore, we found that Tal2 expression is upregulated during oesteoclastogenesis. We show that Tal2 is a direct target gene of the myeloid transcription factor PU.1, which is a key transcription factor for osteoclast gene expression. Strikingly, PU.1 binding to the P1 promoter is conserved between mouse and human, but PU.1 binding to P2 was only detected in human K562 cells. Additionally, we provide evidence that Tal2 influences the expression of the osteoclastic differentiation gene TRACP. These findings provide novel insight into the expression control of Tal2 in hematopoietic cells and reveal a function of Tal2 as a regulator of gene expression during osteoclast differentiation
Density-functional study of bcc Pu–U, Pu–Np, Pu–Am, and Pu–Cm alloys
No full textDensity-functional theory previously used to describe phase equilibria in the gamma-Pu-U-Zr alloys [A. Landa, P. Soderlind, PEA. Turchi, L. Vitos, A. Ruban, J. Nucl. Mater. 385 (2009) 68; A. Landa, P. Soderlind, PEA. Turchi, L. Vitos, A. Ruban, J. Nucl. Mater. 393 (2009) 141], is extended to study ground-state properties of the gamma-Pu-Np, gamma-Pu-Am, and gamma-Pu-Cm solid solutions. Calculated heats of formation are compared with CALPHAD assessments where possible. We discuss how the heat of formation correlates with the charge transfer between the alloy components.</p
Estudo de matrizes elastoméricas de borracha natural e PU/PBDO para aplicação tecnológicas
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2014.Esta tese de doutorado aborda estudos relativos à síntese e caracterização de sistemas elastoméricos de borracha natural e uretano/uréia (PU/PBDO) visando aplicações tecnológicas. Foram investigados diferentes compósitos e/ou sistemas elastoméricos. Sendo caracterizado em função da relação elastômero/dopante e/ou funcionalizações específicas. Assim, cada trabalho seguiu objetivos específicos bem definidos para cada compósito e/ou sistema produzido. Dessa forma podemos dividir os trabalhos em dois grandes grupos, um baseado em amostras contendo a borracha natural outro para amostras produzidas com PU/PBDO. Para o grande grupo da borracha natural, investigou-se o efeito de relaxação inversa em filmes finos dopados com moléculas de azocorante produzidos por casting e submetidos ao processo de fotoalinhamento, onde as anisotropias do substrato combinadas ao processo de secagem produzem a orientação das cadeias poliméricas. Em outro trabalho foram investigados os efeitos de diferentes solventes orgânicos na morfologia de membranas de borracha natural utilizando microscopia de força atômica e análises de leis de escala, onde processos experimentais permitiram obter membranas com baixa rugosidade e/ou altamente rugosas, além disso, uma relação da morfologia com a volatilidade dos solventes foi proposta. Visando propósitos biomédicos, blendas de borracha natural com fosfatos de cálcio (Ca/P) foram produzidas e investigadas, onde buscou-se combinar técnicas experimentais de purificação do processo de centrifugação do látex e incorporação de partículas de Ca/P no volume da matriz de borracha. Neste estudo foram analisadas as interações entre proteínas, na forma de vesículas, remanescentes do látex e partículas de Ca/P, onde verificou-se que as partículas de Ca/P são envolvidas pelas vesículas de proteínas dispersas no volume da matriz polimérica. As propriedades ópticas de membranas de borracha natural, pura e dopada com moléculas orgânicas luminescentes, bem como, a produção por eletrofiação de fibras altamente paralelas com diâmetros micro e sub-micrométricos de borracha natural pura e dopada com luminescente também foram investigadas. Por fim, a fabricação e caracterização de eletrodos elastoméricos pela deposição de nanotubos de carbono, por spray ultrassônico, sobre ?substratos? de borracha natural foram estudadas.Para o sistema elastomérico PU/PBDO realizamos os estudos dasxivpropriedades ópticas, morfológicas e mecânicas para membranas dopadas com diferentes moléculas luminescentes, onde a birrefringência para a membrana pura e a emissão polarizada de um luminescente específico para uma membrana dopada foram testadas em função do alinhamento da matriz polimérica devido a deformação mecânica. Esferas luminescentes com uma face enrugada e outra lisa, chamadas de esferas Janus luminescentes, foram produzidas para o sistema PU/PBDO dopado com Alq3 e caracterizadas via técnicas de microscopia (força atômica, eletrônica de varredura e luminescência óptica) e espectroscopia UV-Vis, além disso, para esse mesmo sistema esferas luminescentes micrométricas foram produzidas pela técnica de microfluídica, onde, para ambos os estudos, o controle das condições experimentais foi alcançado. Por fim, a produção e as caracterizações ópticas de esferas de PU/PBDO luminescentes dopadas com diferentes compostos emissores foram investigadas.Abstract : This PhD thesis report the studies carried using as elastomeric materials the natural rubber (NR) and the urethane/urea synthetic elastomer (polyurethane/polybutadienediol - PU/PBDO) for technological applications. Different composites and/or elastomeric systems were investigated and characterized according to the specific elastomer/dopant system and/or due to their added functionalizations. Therefor, this study followed a specific well-defined objectives for each composite system produced. In this way we can divide this PhD thesis in two large groups, one based on samples containing natural rubber and another for samples produced with PU / PBDO. For the large group of natural rubber, we investigated the effect of inverse relation in thin films doped with azo-dye molecules produced by casting and subjected to photoalignment process. Where the anisotropy of the substrates combined with the drying process produces the orientation on the polymer chains. In another study we investigate the effects in the morphology for natural rubber membranes produced using different organic solvents. For this analyses we used the atomic force microscopy (AFM) combinated with scaling laws. This investigation allowed the achievement of membranes with low and/or high roughness. Moreover, we propose the dependence of the morphology due to the volatility of the solvents. In other study, blends of NR with calcium/phosphorous compounds (NR-Ca/P) were produced to be used in biomedical applications. In this study the interactions between NR protein-particles with pseudomicellar form that are remained after latex centrifugation process and Ca/P particles were investigated. Confocal laser scanning microscopy was used to observe these interactions and we can see that the Ca/P particles are involved by the NR protein-particles dispersed in the polymer matrix and a model was proposed to explain that. Optical properties of natural rubber membranes undoped and doped with luminescent organic molecules were investigated. Moreover, highly parallel fibers with diameters in the micro and sub-micrometer range produced by electrospinning from NR solutions undoped and doped with luminescent were also investigated. Finally, were studied the fabrication of elastomeric electrodes produced using NR membranes as substrate and depositing single-walled carbon nanotubes (SWNT) by ultrasonic spray deposition.xviFor the large group of PU/PBDO elastomeric system, we have studied the optical, mechanical and morphological properties of PU/PBDO membranes undoped and doped with luminescent organic molecules. The polarized photoemission for PU/PBDO luminescent membranes were tested on function of the polymer matrix alignment by mechanical deformation. In another study, we investigate the production of luminescent spheres with tuned surface, where one side was wrinkled and other has remained smooth. This spheres are called luminescent Janus spheres and were produced from PU/PBDO system doped with Alq3. Morphological and optical properties were characterized, being determinated the best parameters of the Janus obtention. In addition, micrometer spheres were produced from the same PU/PBDO-Alq3 system using the microfluidics technique, where the diameter sizes of this spheres were changed adjusting the experimental conditions. Finally, we investigate others luminescent compounds for production of new luminescent PU/PBDO spheres
Influence of the height of carbon nanotubes on hot switching of Au/Cr-Au/MWCNT contact pairs
No full textGold coated Multi-Walled Carbon Nanotube (MWCNT) composites have been used for electrical contact surfaces in previous studies. It was shown that the composite could significantly improve switch lifetime, and exhibited potential as a useful contact material for MEMS switches. The reason is attributed to the contribution of the compressibility of the MWCNT forest, which creates a compliant layer under the gold films. In this study, experiments were performed for samples with different heights of MWCNT forests, namely 30 µm, 50 µm and 80 µm. The influence of MWCNT height on the switching behavior and lifetime were studied. An outcome of the work was that the sample with 80 µm height forests showed the longest lifetime, however the composites with 30 µm and 50 µm forest heights showed lower contact resistances, a parameter of high importance for MEMS switch applications
α-Pu和δ-Pu电子结构的密度泛函理论计算
No full text采用密度泛函理论框架下的平面波赝势方法,对α-Pu和δ-Pu的电子结构进行了对比研究。由电荷布居分析可知,α-Pu中8种位置的原子的轨道电荷分布各不相同,净电荷的得失主要由s和p电子贡献,而δ-Pu中各原子的轨道电荷分布一致,且无净电荷的得失;由态密度可知,α-Pu的态密度主峰较δ-Pu的态密度主峰峰值更低、宽度更宽,表明α-Pu中平均键能强于δ-Pu,导致其更难发生塑性形变。此外,α-Pu电子的能量总体上低于δ-Pu电子的,这也是α-Pu的室温稳定性高于δ-Pu的重要原因。α-Pu中8种不同位置Pu原子的分波态密度的计算结果表明,8号位置Pu原子的5f电子关联性最强,对α-Pu的自旋矩贡献最大,而1号位置Pu原子的5f电子关联性最弱,对自旋矩的贡献最小;由电荷密度图可知,δ-Pu的电子云为均匀的球形,无明显的相互作用,呈现典型的金属键特征,而α-Pu的电子云发生重叠,相互作用明显,具有共价行为,这也在一定程度上揭示了两者呈现不同延脆性机制
Buddhism and Tourism at Pu-Tuo-Shan, China
No full textThis thesis is a study of pilgrimage and religious tourism in a Chinese Buddhist context, with a focus on both the host monastic community and visitors. The selected research site is Pu-Tuo-Shan, one of the Four Buddhist Sacred Mountains of China. While the Western literature on pilgrimage and religious tourism in the context of Buddhism in China remains thin and the many studies in Chinese have their research focus primarily on how to make use of religions to develop tourism and stimulate economic growth, this thesis aims to present the perceptions of Buddhist monks and nuns towards receiving visitors and tourism. The perceptions of religious hosts towards tourism development, and how they cope with the subsequent challenges created by tourism in China, are subjects that have not been studied. Additionally the thesis analyses data derived from a survey of 777 visitors to the island; the quantitative analysis sheds light on the profile of visitors. As elsewhere in the world, the religious sites of China attract not only believers, but also leisure and cultural tourists. The popularity of Pu-Tuo as a tourist destination inevitably disturbs the serenity of the monastic life of the approximately thousand monks and nuns who live there in their monasteries and nunneries. The first objective of this research is to generate a typology of visitors, and this was done through a quantitative approach grounded in post-positivism. The visitor survey was used to construct a visitor typology. The second objective of this thesis, to address how Buddhist monks and nuns perceive receiving visitors and tourism, and their ways to manage visitors’ behaviours, is achieved by adopting a qualitative approach grounded in an interpretive-constructivist paradigm. In-depth interviews with 25 monks and nuns were conducted to capture rich contextual data of their understandings. The two objectives of the thesis are related in the sense that the impact of the visitors on the monastic community and how the monks and nuns perceive their presence in Pu-Tuo depend on the visitors’ reasons for their visits, their behaviour and the strength of their belief in Buddhism. The findings provide insight into how the concepts of ‘pilgrimage’ and ‘pilgrim’ are understood from a Buddhist perspective. The attitudes of the Pu-Tuo Buddhist monks and nuns towards receiving visitors and tourism are found to be mostly welcoming and supportive. This contrasts with the literature on sites belonging to religions other than Buddhism which indicates that tourism is perceived by religious hosts as a burden and as a threat to the sanctity of their religious/sacred sites. Yet, there are challenges created by the visitors in Pu-Tuo and these are noted by the monks and nuns. Their ‘Buddhist way’ of undertaking visitor management is found to be different from what is described in the existing literature about non-Buddhist sites. It is suggested that the empathetic nature of Buddhism is at the root of the visitor management strategies adopted at Pu-Tuo. The findings thereby contribute to the existing scholarly knowledge of how Buddhist sites are managed in the Buddhist way
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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