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Arévalo, Bautista Jazmine Paola. "The role of stat3 phosphorylation state in clear cell renal cell carcinoma (ccRCC)". Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669570.
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STAT3 (signal transducer and activator of transcription 3) és un factor de transcripció latent que regula la transcripció de gens relacionats amb processos biològics essencials tals com: la diferenciació cel·lular, la proliferació, la migració, la inhibició de l’apoptosi i la supervivència. L’activació anormal d’STAT3 s’ha relacionat amb el desenvolupament d’aproximadament el 50% dels càncers humans, incloent el carcinoma renal de cèl·lula clara (ccRCC). Actualment, les propietats oncogèniques d’STAT3 s’atribueixen a la fosforilació del seu residu Tyr705; no obstant, recentment, la fosforilació de la Ser727 ha sorgit com un esdeveniment capaç d’amplificar l’activitat transcripcional d’STAT3, juntament a activitats no genòmiques que promouen el desenvolupament del càncer. El nostre grup va ser un dels pioners en assenyalar la importància de la fosforilació de la Ser727, demostrant que els nivells d’expressió de la pSer727 al nucli (en mostres de teixit de pacients de ccRCC) correlacionaven amb un mal pronòstic i una baixa supervivència global. Donat que el ccRCC és el subtipus histològic de carcinoma renal més prevalent i letal, i que els mecanismes subjacents al seu desenvolupament no han estat determinats fins el moment, l’objectiu d’aquest treball va ser elucidar el paper de l’estat de fosforilació d’STAT3 en el desenvolupament del ccRCC i, específicament, en estudiar la contribució de la pSer727 en la progressió tumoral. Amb aquesta finalitat, es varen generar fosfomutants simples i dobles d’STAT3 (Tyr705Phe, Ser727Ala, Ser727Asp, Tyr705Phe/Ser727Ala, i Tyr705Phe/Ser727Asp) que van ser transduïdes en línies cel·lulars humanes derivades de ccRCC (769-P i 786-O) per avaluar el seu comportament funcional, així com la conseqüent expressió gènica diferencial mitjançant l’anàlisi de microarray. Els nostres resultats han demostrat que les mutants d’STAT3 que contenien una substitució fosfomimètica de la Ser727 (Ser727Asp) promouen un fenotip pro-tumoral in vivo de manera independent a la Tyr705. A més, es descriu que l’estat de fosforilació global d’STAT3 determina l’expressió de diferents subconjunts de gens associats a diversos processos biològics, essent els gens dependents de la pSer727 els més relacionats amb processos característics amb el desenvolupament del càncer. En resum, aquest treball constitueix el primer anàlisi de quin és el paper de l’estat de fosforilació global d’STAT3 en el ccRCC, i demostra que la pSer727 activa la senyalització d’STAT3 a través de la transcripció d’un subconjunt específic de gens que són clínicament rellevants com potencials dianes terapèutiques i nous biomarcadors del ccRCC.STAT3 (signal transducer and activator of transcription 3) es un factor de transcripción latente que regula la transcripción de genes relacionados con procesos biológicos esenciales, tales como: diferenciación celular, proliferación, migración, inhibición de la apoptosis y supervivencia. La activación anormal de STAT3 ha sido relacionada con el desarrollo de cerca del 50% de todos los cánceres humanos, incluyendo el carcinoma renal de célula clara (ccRCC). Actualmente, las propiedades oncogénicas de STAT3 se atribuyen a la fosforilación de su Tyr705; sin embargo, recientemente, la fosforilación de su Ser727 ha surgido como un evento capaz de amplificar la actividad transcripcional de STAT3, aunada a actividades no genómicas que promueven el desarrollo del cáncer. Nuestro grupo fue uno de los pioneros en señalar la importancia de la fosforilación de la Ser727, al demostrar que los niveles de expresión de pSer727 en el núcleo (en muestras de tejidos de pacientes con ccRCC) correlacionaban con un mal pronóstico y baja supervivencia global. Dado que el ccRCC es el subtipo histológico de carcinoma renal más prevalente y letal, y los mecanismos subyacentes a su desarrollo aún no han sido determinados, el objetivo de este trabajo fue elucidar el rol del estado de fosforilación de STAT3 en el desarrollo del ccRCC, y específicamente, en estudiar la contribución de la pSer727 en la progresión tumoral. Para ello, generamos fosfomutantes simples y dobles de STAT3 (Tyr705Phe, Ser727Ala, Ser727Asp, Tyr705Phe/Ser727Ala, y Tyr705Phe/Ser727Asp) que fueron transducidas en líneas celulares humanas derivadas de ccRCC (769-P y 786-O) para evaluar su comportamiento funcional, así como la consecuente expresión génica diferencial a través de un análisis de microarray. Nuestros resultados demostraron que las mutantes de STAT3 que contenían una substitución fosfomimética para la Ser727 (Ser727Asp) promueven un fenotipo pro-tumoral in vivo de forma independiente de la Tyr705. Además, describimos que el estado de fosforilación global de STAT3 determina la expresión de diferentes subconjuntos de genes asociados a distintos procesos biológicos, siendo los genes dependientes de la pSer727, los más relacionados con procesos característicos del desarrollo del cáncer. En resumen, este trabajo constituye el primer análisis acerca del rol del estado de fosforilación global de STAT3 en el ccRCC, y demuestra que la pSer727 activa la señalización de STAT3 a través de la transcripción de un subconjunto específico de genes que son clínicamente relevantes como potenciales dianas terapéuticas y nuevos biomarcadores para el ccRCC.
The signal transducer and activator of transcription 3 (STAT3) is a latent transcription factor that regulates downstream genes involved in essential biological processes such as cell differentiation, proliferation, migration, apoptosis inhibition, and survival. The aberrant activation of STAT3 has been related to the development of near 50% of all human cancers including clear cell renal cell carcinoma (ccRCC). To date, the oncogenic properties of STAT3 are attributed to the phosphorylation of its Tyr705, however, the phosphorylation of its Ser727 has recently emerged as an event that enhances STAT3 transcriptional activity, in addition to non-genomic activities that promote cancer development. Our group was one of the pioneers in bringing the Ser727 phosphorylation to light by demonstrating that nuclear pSer727 expression levels, in tissue samples of ccRCC patients, correlated with poor prognosis and low overall survival. Since ccRCC is the most prevalent and lethal histological subtype of renal cell carcinoma (RCC) and the molecular mechanisms behind its tumorigenesis remain unclear, we aimed to elucidate the role of STAT3 phosphorylation state in ccRCC development, and especially the contribution of pSer727 to tumor progression. For that purpose, we generated simple and double STAT3 phosphomutants (Tyr705Phe, Ser727Ala, Ser727Asp, Tyr705Phe/Ser727Ala, and Tyr705Phe/Ser727Asp) transduced in human-derived ccRCC cell lines (769-P and 786-O), and we evaluated their functional behavior as well as their differential gene expression through microarray analysis. Our data demonstrated that STAT3 mutants carrying a phosphomimetic substitution for Ser727 (Ser727Asp) promote a pro-tumoral phenotype in vitro in a Tyr705-independent manner. Moreover, we describe that the overall STAT3 phosphorylation state determines the expression of different subsets of target genes associated with distinct biological processes, being pSer727-dependent genes the most related to cellular hallmarks of cancer development. In summary, the present study constitutes the first analysis on the role of overall STAT3 phosphorylation state in ccRCC and demonstrates that pSer727 activates STAT3 signaling through transcription of a specific subset of target genes that are clinically relevant as potential therapeutic targets and novel biomarkers for ccRCC.
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Lu, Xibin, i 盧希彬. "Quantitative characterization of mouse embryonic stem cell state transition". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208049.
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Newman, Jamie Jennifer. "Regulation of gene expression and cell state in embryonic stem cells". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/58526.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, June 2010."May 2010." Cataloged from PDF version of thesis.
Includes bibliographical references.
Cell state is established and maintained through the combined action of transcription factors, chromatin regulators and signaling pathways, which all contribute to a transcriptional regulatory circuitry. Embryonic stem (ES) cells are capable of self-renewal and can give rise to nearly all differentiated cell-types, making them an ideal system in which to address the challenges of understanding gene expression and cell state. Valuable insights into the control of cell state have been revealed by recent studies of the ES cell transcriptional regulatory circuitry. Here I present work contributing to the understanding of transcriptional regulatory mechanisms that control ES cell state, specifically signaling pathways and proteins that affect chromatin structure.
by Jamie J. Newman.
Ph.D.
4
Calegari, Federico, i Julieta Aprea. "Bioelectric State and Cell Cycle Control of Mammalian Neural Stem Cells". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-185623.
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The concerted action of ion channels and pumps establishing a resting membrane potential has been most thoroughly studied in the context of excitable cells, most notably neurons, but emerging evidences indicate that they are also involved in controlling proliferation and differentiation of nonexcitable somatic stem cells. The importance of understanding stem cell contribution to tissue formation during embryonic development, adult homeostasis, and regeneration in disease has prompted many groups to study and manipulate the membrane potential of stem cells in a variety of systems. In this paper we aimed at summarizing the current knowledge on the role of ion channels and pumps in the context of mammalian corticogenesis with particular emphasis on their contribution to the switch of neural stem cells from proliferation to differentiation and generation of more committed progenitors and neurons, whose lineage during brain development has been recently elucidated.
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Calegari, Federico, i Julieta Aprea. "Bioelectric State and Cell Cycle Control of Mammalian Neural Stem Cells". Sage-Hindawi, 2012. https://tud.qucosa.de/id/qucosa%3A27972.
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The concerted action of ion channels and pumps establishing a resting membrane potential has been most thoroughly studied in the context of excitable cells, most notably neurons, but emerging evidences indicate that they are also involved in controlling proliferation and differentiation of nonexcitable somatic stem cells. The importance of understanding stem cell contribution to tissue formation during embryonic development, adult homeostasis, and regeneration in disease has prompted many groups to study and manipulate the membrane potential of stem cells in a variety of systems. In this paper we aimed at summarizing the current knowledge on the role of ion channels and pumps in the context of mammalian corticogenesis with particular emphasis on their contribution to the switch of neural stem cells from proliferation to differentiation and generation of more committed progenitors and neurons, whose lineage during brain development has been recently elucidated.
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Orr, Simon Timothy. "Multinuclear solid-state NMR of fuel cell materials". Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/35532/.
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This thesis describes the application of multinuclear solid-state NMR to three materials systems: first, components of polymer-based proton-exchange fuel cells including the fluoropolymer membranes (Chapter 4) and the precious metal supported catalysts (Chapter 5); secondly, the formation of a complex bismuth niobium aluminoborosilicate glass-ceramic with novel dielectric properties (Chapter 6); finally, platinum (II) dialkyldithiophosphates which belong to a class of compounds (metal dialkyldithiophosphates) some of which are used in mineral separation processing (Chapter 7). A full investigation into the effects of different conditions during sample preparation and 19F NMR experiments on fluoropolymer membranes recommended unmilled preparation, dry storage and magic angle spinning below 24 kHz for the study of structural differences between membranes. The application of 19F NMR to a range of commercial and experimental fluoropolymer membranes revealed that the equivalent weight does not affect the mobility of the polymer molecules such that can be detected by this technique. Calculations of equivalent weight from 19F NMR differed with quoted values by up to 14%. Discrepancies were smallest in the short sidechain polymers, as low as 3%. The assignment of spectra was invariant with sidechain structure apart from a change in the number of ester links. The presence or absence of oxygen affected chemical shielding even around nuclei separated by several bonds. Differences in 1H linewidths between membranes could not be interpreted without the control and comparison of manufacturing techniques. It is desirable to remove the necessity for organic solvents in membrane casting. However, membranes cast from aqueous solution do not possess the same properties as those from propanol. It had been proposed that rapid drying of water cast membranes would result in a structure more similar to those from organic solvent. 1H NMR revealed that the opposite is the case, rapid drying makes the ordinarily more inhomogeneous aqueous membranes even more so. The application of both 19F and 1H NMR revealed that the monomolecular layers of fluoropolymer deposited on the surface of fuel cell catalysts to aid proton conductivity are categorically different in nature to the same materials in the bulk state. 19F NMR suggests a polymer structure either more disordered, greatly less mobile or both. 1H NMR displayed water environments that could not be reconciled to the standard model of rapid exchange between bulk water and water associated with acid groups. Spectral differences caused by solvent and polymer loading were discussed. The first complete and quantitative Fourier transformed 195Pt NMR spectra of platinum fuel cell catalysts, acquired using a field sweeping method, are analysed for deviation from the cubooctohedral particle model and surface oxidation. A combination of 11B, 27Al and 29Si studies of the BN1 ceramic system after different temperature heat treatments confirmed much of the previous work on phase evolution. However, it was shown that kyanite does not make up a significant proportion of the material until heat treatment reaches 1000 ºC and that aluminium impurities in bismuthbiobate crystals appear to increase with treatment temperature. The nature and abundance of glassy phases in the system are explored for the first time. Field sweep 195Pt NMR was employed to characterise the 195Pt chemical shift anisotropy of five platinum (II) dialkyldithiophosphates complexes. Additionally the 31P chemical shift anisotropies of two of the complexes, previously unpublished are presented.
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Bryan, Andrea K. (Andrea Kristine). "Cell State Identication by Mass, Density, and volume". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67071.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 119-124).
Cell size is often overlooked in the drive to define molecular mechanisms, but as a basic physical property it is an integrator of the cell's metabolic rate and indicator of cell fate. Development of the Suspended Microchannel Resonator (SMR), a microfluidic mass measurement system, enables femtogram cell mass resolution, and the resistive pulse (Coulter) technique provides high-speed electronic readout of cell volume. With these tools, we developed four methods to measure cell density, the ratio of mass to volume. We first measure the average density of cell populations using the SMR and a Coulter counter. We observe that cell density increases prior to bud formation at the G1/S transition of budding yeast, which is consistent with previous measurements using density gradient centrifugation. To investigate the origin of this density increase, we use the SMR to measure buoyant mass in high density media and monitor relative density changes of growing yeast cells. We find that the density increase requires energy, function of the protein synthesis regulator TOR, passage through START, and an intact actin cytoskeleton. These techniques are suitable for most non-adherent cells and subcellular particles to characterize cell growth in a variety of applications. We next develop two platforms to measure single-cell mass, volume, and density. These properties are calculated from two SMR buoyant mass measurements, each in different density fluids. These measurements are achieved by serially connecting two SMR structures through a microchannel with an intermediate T-junction, such that a cell is measured by each SMR in different density fluids. Similar measurements can also be made with one SMR by reversing the SMR fluid flow after a cell is measured-each cell re-enters the SMR in a higher density fluid for a second measurement. We find that the intrinsic cell-to-cell density variation is nearly 100-fold smaller than the mass or volume variation, and by simultaneously measuring density and mass, we identify distinct subpopulations of diseased and healthy cells that are indistinguishable by mass or volume alone.
by Andrea K. Bryan.
Ph.D.
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Fonseca, Aaron James. "State-Space Randles Cell Model for Instrument Calibration". Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31790.
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It is desirable to calibrate electrochemical impedance spectroscopy (EIS) instrumentation using a Randles circuit. This presents a challenge as realistic loads, simulated by this circuit, contain theoretical components (Warburg elements) that are difficult to model. This thesis proposes a state-space solution to this problem and explores the process of realizing a digital high-accuracy approximation of a Randles circuit for the purposes of verifying and calibrating EIS instrumentation. Using Valsa, Dvo{\v r}{\'a}k, and Friedl's network approximation of a Warburg element, a collection of state-space relations describing the impedance of a Randles circuit are derived. From these equations the process of realizing a digital system is explored; this includes a discussion on methods of discretization, an overview of the challenges of realizing digital filters, and an analysis of the effects that finite word-length has on the accuracy of the model when using fixed-point hardware.
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Wang, Peng. "Some improvements in state/parameter estimation using the cell-to-cell mapping technique /". The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486402544591959.
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McBride, Jared Adam. "Steady State Configurations of Cells Connected by Cadherin Sites". BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6023.
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Many cells employ cadherin complexes (c-sites) on the cell membrane to attach to neighboring cells, as well as integrin complexes (i-sites) to attach to a substrate in order to accomplish cell migration. This paper analyzes a model for the motion of a group of cells connected by c-sites. We begin with two cells connected by a single c-site and analyze the resultant motion of the system. We find that the system is irrotational. We present a result for reducing the number of c-sites in a system with c-sites between pairs of cells. This greatly simplifies the general system, and provides an exact solution for the motion of a system of two cells and several c-sites.Then a method for analyzing the general cell system is presented. This method involves 0-row-sum, symmetric matrices. A few results are presented as well as conjectures made that we feel will greatly simplify such analyses. The thesis concludes with the proposal of a framework for analyzing a dynamic cell system in which stochastic processes govern the attachment and detachment of c-sites.
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Ganbat, Atarsaikhan. "Reducibility of steady-state bifurcations in coupled cell systems". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188451.
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Smith, Nina A. "Measurement of Red Blood Cell Oxygenation State by Magnetophoresis". Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1568890258014352.
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Esmaeili, Pourfarhangi Kamyar. "Movie1: MTLn3 cell switching from Migration to Invadopodia state". Diss., Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/584756.
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Bioengineering;Ph.D.;
Metastasis is the leading cause of death among cancer patients. The metastatic cascade, during which cancer cells from the primary tumor reach a distant organ and form multiple secondary tumors, consists of a series of events starting with cancer cells invasion through the surrounding tissue of the primary tumor. Invading cells may perform proteolytic degradation of the surrounding extracellular matrix (ECM) and directed migration in order to disseminate through the tissue. Both of the mentioned processes are profoundly affected by several parameters originating from the tumor microenvironment (extrinsic) and tumor cells themselves (intrinsic). However, due to the complexity of the invasion process and heterogeneity of the tumor tissue, the exact effect of many of these parameters are yet to be elucidated. ECM proteolysis is widely performed by cancer cells to facilitate the invasion process through the dense and highly cross-linked tumor tissue. It has been shown in vivo that the proteolytic activity of the cancer cells correlates with the cross-linking level of their surrounding ECM. Therefore, the first part of this thesis seeks to understand how ECM cross-linking regulates cancer cells proteolytic activity. This chapter first quantitatively characterizes the correlation between ECM cross-linking and the dynamics of cancer cells proteolytic activity and then identifies ß1-integrin subunit as a master regulator of this process. Once cancer cells degrade their immediate ECM, they directionally migrate through it. Bundles of aligned collagen fibers and gradients of soluble growth factors are two well-known cues of directed migration that are abundantly present in tumor tissues stimulating contact guidance and chemotaxis, respectively. While such cues direct the cells towards a specific direction, they are also known to stimulate cell cycle progression. Moreover, due to the complexity of the tumor tissue, cells may be exposed to both cues simultaneously, and this co-stimulation may happen in the same or different directions. Hence, in the next two chapters of this thesis, the effect of cell cycle progression and contact guidance-chemotaxis dual-cue environments on directional migration of invading cells are assessed. First, we show that cell cycle progression affects contact guidance and not random motility of the cells. Next, we show how exposure of cancer cells to contact guidance-chemotaxis dual-cue environments can improve distinctive aspects of cancer invasion depending on the spatial conformation of the two cues. In this dissertation, we strive to achieve the defined milestones by developing novel mathematical and experimental models of cancer invasion as well as utilizing fluorescent time-lapse microscopy and automated image and signal processing techniques. The results of this study improve our knowledge about the role of the studied extrinsic and intrinsic cues in cancer invasion.
Temple University--Theses
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López, Ayón Gabriela. "Applying a commercial atomic force microscope for scanning near-field optical microscopy techniques and investigation of Cell-cell signalling". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92400.
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The field of research of this thesis is Condensed Matter Physics applied to Biology. Specifically it describes the development of different Atomic Force Microscopy techniques and tools towards the study of living cells in physiological solution. Particular interest is put into the understanding of the influence of noise in the determination of ordered liquid layers above a mica surface - as work towards the study of the role of water and ions in biological processes - and the influence of "diving bell" to boost the Q factor and allow stable imaging and force spectroscopy with tips based on Scanning Near-field Optical Microscopy [LeDue, 2010 and LeDue, 2008]. By combining SNOM techniques as a local illumination method (and thus avoiding photo bleaching of individual molecules) and high resolution AFM techniques we will be able to investigate mechano-transduction and associated signaling in living cells and individual proteins.Le domaine de recherche de cette thèse consiste en l'application de la physique de la matière condensée à la biologie. Plus précisément, ce travail décrit le développement de différentes techniques de Microscopie à Force Atomique (MFA) et d'outils permettant l'étude de cellules vivantes en solution physiologique. Un intérêt particulier est porté à la compréhension de l'influence du bruit dans la détermination de couches liquides ordonnées au-dessus d'une surface de mica - en tant que travail préalable à l'étude du rôle de l'eau et des ions dans les processus biologiques - et de l'influence d'une "cloche de plongée" pour renforcer le facteur Q ainsi que pour permettre l'imagerie stable et la spectrométrie de force avec des sondes basées sur la Microscopie Optique en Champ Proche (MOCP). En combinant des techniques MOCP, utilisées comme méthode d'éclairement local (évitant ainsi le photoblanchiment des molécules individuelles), et des techniques MFA haute résolution, nous serons capables d'investir la mécano-transduction et le signalement associé dans des cellules vivantes et dans des protéines individuelles.
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Screaton, Robert A. "Effects of carcinoembryonic antigen (CEA) and Myc on cell state transitions". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0016/NQ55422.pdf.
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Chang, Kuo-Hsuan. "Identification and characterization of a LIF-STAT3/Activin-Smad2/3 dual responsive pluripotent stem cell state". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6343.
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The medical and bioindustrial applications of pluripotent stem cells rely on our understanding of their biology. Pluripotent stem cell lines derived from embryos in different stages depend on distinct signalling pathways. Embryonic stem cells (ESCs), derived from the inner cell mass (ICM) of preimplantation embryos, are dependent on LIF/STAT3 signalling, while epiblast stem cells (EpiSCs), established from the postimplantation embryos, require Activin A/Smad2/3 signalling. Recent studies revealed the presence of intermediate pluripotent stem cell populations. Their growth factor responsiveness, gene expression pattern and associated chromatic signatures, are compatible with the state intermediate between ESCs and EpiSCs. However, it remains unknown whether such cell populations represent a stable clonally intermediate cell state. In this thesis, I describe the discovery and characterization of novel stem cell lines displaying gene expression pattern intermediate between ESCs and EpiSCs. These cells respond to LIF/STAT3 as well as Activin/Smad2/3 signalling at single cell level. They can integrate into the ICM and generate chimeric embryos. In keeping with a more advanced differentiation stage than that of ESCs, the LIF/Activin dual responsive stem cells showed accelerated temporal gene expression kinetics during in vitro differentiation in embryo bodies. I found that these properties are shared by some induced pluripotent stem cell (iPSC) lines. The notion of an intermediate state was consolidated by a genome-wide microarray profiling. The hierarchical clustering analysis grouped LIF/Activin dual responsive stem cells together into a cluster intermediate between ESCs and EpiSCs. These findings advanced our understanding of the regulation of pluripotency. A better understanding of distinct differentiation state of pluripotent stem cells and their signalling responsiveness is crucial for developing tailored strategies for lineage/cell type differentiation.
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Buder, Thomas, Andreas Deutsch, Michael Seifert i Anja Voss-Böhme. "CellTrans: An R Package to Quantify Stochastic Cell State Transitions". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-230144.
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Many normal and cancerous cell lines exhibit a stable composition of cells in distinct states which can, e.g., be defined on the basis of cell surface markers. There is evidence that such an equilibrium is associated with stochastic transitions between distinct states. Quantifying these transitions has the potential to better understand cell lineage compositions. We introduce CellTrans, an R package to quantify stochastic cell state transitions from cell state proportion data from fluorescence-activated cell sorting and flow cytometry experiments. The R package is based on a mathematical model in which cell state alterations occur due to stochastic transitions between distinct cell states whose rates only depend on the current state of a cell. CellTrans is an automated tool for estimating the underlying transition probabilities from appropriately prepared data. We point out potential analytical challenges in the quantification of these cell transitions and explain how CellTrans handles them. The applicability of CellTrans is demonstrated on publicly available data on the evolution of cell state compositions in cancer cell lines. We show that CellTrans can be used to (1) infer the transition probabilities between different cell states, (2) predict cell line compositions at a certain time, (3) predict equilibrium cell state compositions, and (4) estimate the time needed to reach this equilibrium. We provide an implementation of CellTrans in R, freely available via GitHub (https://github.com/tbuder/CellTrans).
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Van, Schalkwyk Carlo. "Full state control of a Fury X-Cell unmanned helicopter". Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2934.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.This thesis describes the successful development of an autopilot for an unmanned radio controlled helicopter. It presents a non-linear helicopter model. An adaptive linearised model is derived and used to design a controller. The adaptive full state controller is tested in various ways, including two aerobatic manoeuvres. A number of analyses are performed on the controller, including its robustness to parameter changes, noisy estimates, wind and processing power. The controller is compared with a non-adaptive counterpart, which leads to the conception, design and analysis of a much improved control structure. Practical flight test results are presented and analysed. In some instances available literature was reworked and re-derived to produce a genericmodel-controller package that can easily be adapted for helicopters of any make, model and size.
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Berti, Federica. "Protection of the muscle stem cell state from premature differentiation". Thesis, University of Portsmouth, 2016. https://researchportal.port.ac.uk/portal/en/theses/protection-of-the-muscle-stem-cell-state-from-premature-differentiation(6886509a-35fa-43b1-8971-7cb2dcaa7da3).html.
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The extraordinary capacity of regeneration exists in just certain species and tissue types. Invertebrates, the cells that regenerate tissues are called stem cells. During adulthood, damaged muscle tissue regenerates through Satellite stem cells that re-enter the cell cycle from a quiescent state, giving rise to new muscle tissue. During development, newly forming organisms build tissues through proliferating stem cells that renew the stem cell pool whilst generating myogenic stem cells which will eventually differentiate into muscle cells. For many years the Myogenic Regulatory Factors (Mrf) genes have been considered to be the main genes driving this proliferation in adult and fetal stages. Mrf genes have been shown to be capable of inducing non-myogenic cells to enter the myogenic lineage in vitro, but their role and capabilities in vivo have been less well characterised. Here we show, using the developing chicken model, that Mrf genes and related genes are not capable of prematurely upregulating terminal muscle differentiation before HH20. MyoD and other combinations of gene misexpression were however shown to be capable of inducing Myosin upregulation between HH20 and HH24 indicating the existence of a time-frame dependent protection of premature development. These results indicate that the Mrf genes have a reduced proficiency for inducing differentiation in vivo compared with in vitro likely due to the presence of currently unidentified additional factors. Our results demonstrate that the current understanding of the signals and cues of muscle stem cell differentiation are still insufficient to exploit the regenerative capabilities of muscle tissues towards regenerative therapies. The possible additional factors required for muscle stem cell differentiation are also discussed.
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Trajkova, Aneta. "Study of regulators and molecular pathways of cell state conversions". Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10221.
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La génération de cellules souches pluripotentes induites (iPSC) par reprogrammation et de cellules cancéreuses par transformation oncogénique sont deux processus en plusieurs étapes au cours desquels des changements coordonnés de plasticité et d'identité cellulaires se produisent. Cependant, les circuits moléculaires impliqués dans les deux processus, leur degré d'analogie et d'interaction fonctionnelle restent mal caractérisés. Nous nous sommes donc intéressés à identifier les facteurs qui contribuent au maintien de l'identité cellulaire et à l'acquisition de la plasticité cellulaire au cours de ces deux processus. En explorant les trajectoires cellulaires de reprogrammation et de transformation qui conduisent à la perte d'identité cellulaire dans les fibroblastes embryonnaires primaires de souris (MEFs), nous avons identifié plusieurs facteurs de transcription (FT). Mon travail de thèse visait donc à comprendre comment ces FT pourraient être impliqués dans la régulation de l'identité et de la plasticité cellulaires au cours de la reprogrammation et de la transformation mais aussi au cours d'autres processus de conversion d'état cellulaire tels que la transdifférenciation et à identifier les mécanismes moléculaires impliqués. Nous avons d'abord identifié le FT Atoh8 comme un inhibiteur de la plasticité cellulaire, à la fois cible et régulateur rétroactif de cMyc et de la voie Wnt. Par ailleurs, nous avons montré que la perte d'identité cellulaire dans les intermédiaires cellulaires précoces de conversion d'état est corrélée à un changement d'expression des FT paralogues Bcl11a et Bcl11b. De plus, en utilisant des approches de perte de fonction, nous avons révélé que la modulation de cet équilibre contrôle l'émergence des iPSC, des cellules transformées et transdifférenciées. L'exploration de la liaison physique de ces FT sur la chromatine lors de la reprogrammation nous a conduit à proposer que Bcl11b s'oppose aux conversions d'état cellulaire par une liaison persistante aux gènes de différenciation, tandis que Bcl11a favorise les conversions d'état en régulant partiellement le statut mésenchymateux/épithélial des cellulesThe generation of induced pluripotent stem cells (iPSC) by reprogramming and of cancer cells by oncogenic transformation are both multistep processes during which coordinated changes of cellular plasticity and identity occur. However, the molecular circuitries involved in both processes, their degree of analogy and of functional interplay remain poorly characterized. We were therefore interested in identifying factors that contribute to cellular identity maintenance and cellular plasticity acquisition during both processes. By exploring the reprogramming and transforming roadmaps leading to cellular identity loss in primary mouse embryonic fibroblasts (MEFs), we have identified several transcription factors (TFs). My PhD work therefore aimed to understand how these TFs could be involved in regulating cellular identity and plasticity during reprogramming and transformation but also during other cell state conversion processes such as transdifferentiation and to finally identify the molecular mechanisms implied. We first identified the TF Atoh8 a as broad plasticity inhibitor, both a target and retroactive regulator of cMyc and the Wnt pathway. Moreover, we showed that cellular identity loss in early cell state conversions intermediates is correlated with a switch in the expression of the paralog TFs Bcl11b and Bcl11a. In addition, using loss-of-function approaches, we revealed that the modulation of this balance controls the emergence of iPSC, transformed and transdifferentiated cells. The exploration of the physical binding of these TFs on chromatin during reprogramming led us to propose that Bcl11b opposes to cell state conversions by persistent binding to differentiation genes, while Bcl11a favours state conversions by partially regulating the mesenchymal/epithelial status of the cells
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Ching, Ada Sik-Lun. "Cell cycle studies in Paramecium : effects of abrupt changes of nutritional state on cell cycle regulation". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24595.
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The controls over initiation of DNA synthesis, initiation of cell division, regulation of macronuclear DNA content, and the relationship between cell mass and growth rate were examined in cells growing under nutrient constraint, or in cells experiencing a change in growth conditions through nutritional enrichment (shift-up) or nutritional shift-down.
Reduction in both cell mass and DNA content was achieved by growing Paramecium cells under nutritional limitation in the chemostat. Under the extreme condition in the chemostat, the normally balanced relationship between DNA content and cell mass (Berger, 1984 Kimball, 1967) is uncoupled. The DNA content in these cells is maintained at about 50 units, but cell mass can be as little as 24% of normal. The generation time in these slow growing cells was increased 4 to 5 times that of rapidly growing cells; the growth rate was also reduced by about the same proportion. Nutritional shift-up was done by transferring the chemostat cells to medium of excess food. Similarly, nutritional shift-down was performed by transferring cells either to the chemostat or to exhausted medium.
The timing of DNA synthesis initiation is largely determined in the preceding cell cycle. Although growth rate (protein synthesis rate) responds quickly to the new conditions, the timing of DNA synthesis initiation is not readjusted immediately and reflects that of the parental cell cycle. The rate at which cells enter S phase however, is affected by a reduction in growth rate.
The criteria for DNA synthesis initiation are not determined by cell mass per se. First, cell mass increases to about 180% of the initial G1 value at the time of DNA synthesis initiation following a nutritional shift-up. This value is much greater than that of well-fed controls (118%). However, the increase in cell mass up to the mean time of DNA synthesis initiation and cell division are not significantly different than that observed in well-fed cells. This suggests a mass-related control over initiation of DNA synthesis. Second, cells initiate DNA synthesis even when there is a net decrease in cell mass following nutritional shift-down. Thus, an increase in cell mass per se is not necessary for DNA synthesis initiation. Unlike initiation of DNA synthesis, the regulatory mechanisms determining the macronuclear DNA synthesized reflects solely the current nutrient conditions. Cells in chemostat culture normally maintain about half the normal amount of DNA (about 50 units). Following nutritional shift-up cells synthesize 100 units of DNA instead. Similarly cells synthesize only 50 units of DNA following nutritional shift-down. The amount of DNA synthesized, therefore, is related to the growth rate, and as discussed later, is also related to the commitment point to cell division.
This study also reveals that the point of initiation of cell division is not time-dependent. It does not occur at a fixed duration following the previous fission or the initiation of DNA synthesis. The point of commitment to division occurs at about 95 minutes before fission regardless of growth rate. Analysis of the effects of macronuclear DNA synthesis inhibition in cc1 cells after the transition point for division indicate that cells synthesize 50 units of DNA before the point of commitment to division. This suggests that cells are committed to divide after synthesizing about 50 units of DNA. Following this point, rapidly growing cells will produce 50 units of DNA before fission; whereas slow growers will accumulate an amount proportional to their growth rate. There are reasons to believe that the threshold value of DNA for commitment to cell division may be 41 units instead of 50.Science, Faculty of
Zoology, Department of
Graduate
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Wang, Bo. "SOLID STATE AND LIQUID STATE NANOCRYSTALLINE SOLAR CELLS ON RIGID AND FLEXIBLE SUBSTRATES". Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1281658251.
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Annavajjula, Vamsi Krishna. "A FAILURE ACCOMMODATING BATTERY MANAGEMENT SYSTEM WITH INDIVIDUAL CELL EQUALIZERS AND STATE OF CHARGE OBSERVERS". University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1190318540.
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Wang, Stan. "Reprogramming and epigenetic factors regulating pluripotency and the stem cell state". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709334.
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Cacau, Ronny Glauber de Almeida. "Inverter five levels based on switching cell multi-state type T". Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14584.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoEste trabalho apresenta o estudo, projeto e implementaÃÃo de um inversor multinÃvel monofÃsico baseado na cÃlula de comutaÃÃo de mÃltiplos estados tipo T (5L-CCME-T2) para aplicaÃÃes em baixa tensÃo e elevadas correntes. A topologia proposta visa estender a aplicaÃÃo da cÃlula de comutaÃÃo de mÃltiplos estados (CCME) para a estrutura do conversor de trÃs nÃveis tipo T, proporcionando cinco nÃveis na tensÃo de saÃda antes do filtro e, consequentemente, uma reduÃÃo do conteÃdo harmÃnico e maior qualidade da tensÃo de saÃda. Outra caracterÃstica desta topologia à a distribuiÃÃo uniforme da corrente total de saÃda entre os semicondutores do conversor, proporcionando menores perdas por conduÃÃo e elevado rendimento. AlÃm disso, à possÃvel reduzir o peso e volume dos magnÃticos, uma vez que a frequÃncia de operaÃÃo dos elementos reativos à o dobro da frequÃncia de comutaÃÃo dos interruptores. Um estudo teÃrico com anÃlise qualitativa e quantitativa do inversor proposto e metodologia de projeto foi realizado. A estratÃgia de controle implementada tem como objetivo o controle da tensÃo de saÃda e das tensÃes do barramento CC. A tÃcnica de modulaÃÃo empregada à a convencional modulaÃÃo por largura de pulso senoidal (SPWM). A validaÃÃo da topologia à realizada atravÃs dos resultados de simulaÃÃo e experimentais de um protÃtipo desenvolvido para uma potÃncia de saÃda de 5 kW.
This work presents the study, design and implementation of a multilevel converter based on T - type multi - state switching cell (5L - MSSC - T 2 ) for applications in low voltages and high currents. The proposed topology aims to extend the application of the multi - state switching cell (MSSC) to the structure of the three - level T - type converter, providing five levels in the output voltage before the filter and, consequently, a reduction of the harmonic content and higher output vol tage quality. Another feature of this topology is the uniform distribution of the total output current between the semiconductors of the converter, providing lower conduction losses and high efficiency. Furthermore , it is possible to reduce the weight and volume of magnetics, since the operating frequency of reactive elements is twice the switching frequency of the switches. A theoretical study with qualitative and quantitative analysis of the proposed inverter and the design methodology was performed . The control strategy implemented aims to control the output voltage and the DC bus voltages. The employed modulation technique is the conventional sinusoidal pulse width modulation (SPWM) . The validation of the topology is verified through simulation and exper imental results of a developed prototype for an output power of 5 kW
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Tervo, O. (Oskari). "Effective channel state acquisition in multi-cell multi-user MIMO system". Master's thesis, University of Oulu, 2013. http://urn.fi/URN:NBN:fi:oulu-201306011414.
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In a cellular network with small cells, where all the communication resources are shared, the inter-cell interference becomes a limiting factor of performance. The strategies for mitigating the inter-cell interference has been quite extensively studied lately. One of the promising candidates is coordinated beamforming/scheduling, where a certain number of cells is allowed to cooperate such that the transmission from each cell takes into account the interference it would cause to the users of other cells. In this thesis, the performances of different signaling strategies which perform the weighted sum rate maximization in time division duplex multi-cell multi-user MIMO downlink system are studied. The strategies consist of iterative decentralized algorithms, aiming at reduced pilot signaling overhead and faster convergence. The required control information between the cells is provided via uplink reference signals and a backhaul. Uplink reference signals include sounding reference signals and busy bursts. Based on the earlier work, the strategies have now been extended to a larger cellular system in which the frequency selectivity and the uncertainty of the channel information are also taken into account. The ability of the strategies to handle the large network can be seen from the simulation results. It is shown that even when there is strong inter-cell interference, the strategies utilizing parallel cell-specific iterations offer practical convergence speed. It is also noticed that the joint optimization over many frequency blocks brings a minor improvement on the sum rate performance, meaning that it could also be utilized with the same order of computational complexity compared to the frequency flat case. Finally, the robustness of the centralized strategy to the imperfect channel state information is shown and the trade-off between the CSI uncertainty and multi-user diversity is statedSolukkoverkossa, jossa solujen koot ovat pieniä ja kaikki käyttävät samoja taajuuksia, solujen välinen häiriö rajoittaa verkon suorituskykyä. Viime aikoina on laajasti tutkittu strategioita, joilla häiriötä saataisiin vähennettyä. Yksi lupaavista menetelmistä tähän tarkoitukseen on koordinoitu keilanmuodostus/skedulointi, jossa tietty ryhmä soluja voi koordinoida keskenään ja näin ottaa huomioon lähetyksestä aiheutuvan häiriön toisia soluja kohtaan. Tässä diplomityössä tutkitaan erilaisten painotetun summadatanopeuden maksimoivien signalointistrategioiden suorituskykyä aikajakodupleksoidussa usean solun ja käyttäjän moniantenniverkossa, jossa dataa lähetetään tukiasemasta käyttäjille. Strategiat perustuvat iteratiivisiin hajautettuihin algoritmeihin, joiden tarkoituksena on vähentää opetussignaloinnista aiheutuvaa kuormitusta ja nopeuttaa suppenemista. Kontrolli-informaation signaloimiseen verkossa käytetään käyttäjiltä tukiasemille lähetettäviä opetussignaaleja ja taustayhteyttä tukiasemien välillä. Työ perustuu aiemmin tehtyyn tutkimukseen, josta strategiat on nyt laajenettu suurempaan solukkojärjestelmään, ottaen huomioon myös taajuusselektiivisyyden ja kanavainformaation epävarmuuden vaikutukset. Simulointitulosten perusteella voidaan sanoa, että strategiat toimivat usean käyttäjän ja solun verkossa. Tuloksista nähdään, että rinnakaisia solukohtaisia iteraatioita hyödyntävillä strategioilla voidaan saavuttaa käytännöllinen suppenemisnopeus, vaikka solujen välinen häiriö on voimakasta. Taajuusselektiivisen kanavan tuloksista huomataan, että yhteisoptimointi usean taajuuslohkon yli parantaa vähän suorituskykyä verrattuna yhden taajuuden tapaukseen. Yhteisoptimointia voitaisiin siis myös hyödyntää, koska laskennallinen monimutkaisuus on samaa suuruusluokkaa verrattuna yhden taajuuden tilanteeseen. Epävarman kanavatiedon vaikutusta tutkitaan keskitetyllä optimointimenetelmällä, joka selvästi laskee suorituskykyä verrattuna täydellisen kanavan tapaukseen, mutta antaa kuitenkin selkeän parannuksen alkuperäiseen algoritmiin verrattuna. Koska opetussignaalien teho jaetaan käyttäjien kesken, tulokset näyttävät kompromissin kanavatiedon epävarmuuden ja monikäyttäjädiversiteetin välillä
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Lamon, Gaëlle. "Structural characterization of fungal cell walls architecture by solid-state NMR". Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0314.
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Il existe une grande variété de champignons pathogènes humains qui sont à l’origine de maladies bénignes à mortelles. La plupart du temps, ces infections sont associées à d’autres pathologies ou traitements médicaux comme l’asthmes, les leucémies, les transplantations d’organes, le SIDA ou les traitement immunosuppresseurs à base de corticostéroides. Malgré le nombre important de décès et le nombre grandissant d’occurrence des mycoses sévères à travers le monde, les infections fongiques sont encore négligées par les autorités sanitaires.Parmi ces pathogènes fongiques, le champignon filamenteux Aspergillus fumigatus est un des pathogènes principaux du système respiratoire. L’aspergillose, dont les taux de d’infection et de mortalité demeurent élevés, devient un enjeu de santé publique. Les spores d’A. fumigatus sont entourés d’une paroi, essentielle pour leur croissance et leur permettant de résister face au système immunitaire de l’hôte. Cette paroi est composée d’un réseau de polysaccharides recouvert d’un pigment appelé DHN-mélanine et d’une couche de protéines appelées hydrophobines. Ce projet a pour but d’établir l’architecture structurale de la paroi des spores d’A. fumigatus à l’échelle atomique en utilisant la RMN du solide (ssNMR) en rotation à l’angle magique (MAS).D’un autre côté, Cryptococcus neoformans est l’agent pathogène responsable de la cryptococcose ; une mycose affectant le système nerveux central. Cette maladie fongique est, encore de nos jours, une cause significative de mortalité à travers le monde puisqu’elle entraîne de graves symptômes tels que la méningo-encéphalite ; particulièrement fréquente chez les patients déjà infectés par le VIH. C. neoformans se présente sous la forme d’une cellule encapsulée de 5 à 7 μm de diamètre entourée d’une paroi et d’une capsule. Cette paroi, rigide, est liée à la membrane plasmique et composée de polymères d’α-glucan, de β-glucan, de chitine et de chitosan. De plus, la capsule de C. neoformans est majoritairement composée de carbohydrates tels que le glucuronoxylomannan (GXM) (jusqu’à 90 %) ou le glucuronoxylomannogalactan (GXMGal) mais aussi de mannoprotéines et de lipides. Le but de ce projet de thèse est d’identifier les différents composants de la paroi mais aussi de la capsule de C. neoformans par ssNMR et d’établir l’architecture de ces deux entités. Un des aspects de ce projet est aussi d’explorer les possibilités et les limitations des méthodes de détection proton en RMN couplée à un MAS élevé (100 kHz) comme outil d’analyse des parois fongiques.En résumé, puisque la RMN des solides est une méthode de spectroscopie non invasive, nous avons appliqué ce type d’analyses dans le cadre de l’étude de l’architecture moléculaire de systèmes complexes (parois fongiques, capsules, …) dans des conditions aussi proches que possible de l’état natif des cellules. Pendant ces trois années de thèse, nous avons mis en place une méthodologie robuste et rapide permettant d’étudier la composition complexe des structures externes présentes dans les cellules fongiques ainsi que leur architecture au sein des cellules entières. De plus, puisque dans le cadre des infections microbiennes la pathogénicité du microbe repose souvent sur les structures externes des cellules infectieuses, les résultats obtenus au court de cette thèse, apportant une meilleure compréhension de l’organisation cellulaire d’A. fumigatus et C. neoformans, pourraient ainsi être utilisés dans le cadre du développement et de la mise en place de nouvelles stratégies thérapeutiques afin de combattre plus efficacement ces infections fongiquesThere is a broad range of fungal pathogen infecting humans and causing diseases that can be from mild to lethal. Severe fungal infections are due to opportunistic pathogens that infect immunosuppressed individuals and are most of the time associated with other diseases or medical conditions such as asthma, leukemia, organ transplants, AIDS or immunosuppressive corticosteroid therapies. Despite the number of deaths and the increase in severe mycosis, fungal infections remain neglected by public health authorities.Among fungal pathogens, the filamentous fungus Aspergillus fumigatus is one of the major pathogen of the respiratory system. Aspergillosis displaying both high incidence and mortality rates, is becoming a massive public health issue. The spores of Aspergillus fumigatus are surrounded by a cell wall, essential for their growth and allowing them to resist against host defense mechanisms. The cell wall is composed of a set of polysaccharides covered by the DHN-melanin pigment and a layer of proteins called hydrophobins. In this project, we aimed at investigated the structural architecture of Aspergillus fumigatus cell wall at atomic resolution using MAS ssNMR spectroscopy.In another hand, Cryptococcus neoformans is the etiological agent of cryptococcosis; which consists in mycosis affecting the central nervous system. This fungal disease remains a significant cause of mortality worldwide by leading to severe symptoms such as meningoencephalitis - especially for immunocompromised individuals suffering from AIDS. C. neoformans results in encapsulated particles with a size of 5-7μm with a two-layers external structure composed of a cell wall and a capsule. The cell wall, rigid, is bounded to the plasma membrane and composed of polymers of α-glucan, β-glucan, chitin and chitosan45. Then, the capsule of C. neoformans is mainly composed of carbohydrates such as glucuronoxylomannan (GXM) (up to 90%), glucuronoxylomannogalactan (GXMGal), mannoproteins and lipids. During this thesis project, we aimed at identifying the different components of C.neoformans cell wall and capsule by ssNMR and to investigate the architecture of these two layers. Part of this project was also the exploration of possibilities and limits of 1H detection methods at fast MAS regime (100 kHz) as the tool to analyze intact cell walls.To sum up, as the solid-state NMR is a non-destructive spectroscopy, we applied this method to the study of the molecular architecture of complex systems (cell wall, capsule…) in cellular conditions – as close as possible to the native state. During these three years, we set up a methodology allowing studying the complex composition of fungal external structures as well as their architecture in the cell context. Finally, because in microbial infections, the pathogenesis often relies on the external structures of the pathogen, all these results could give a better comprehension of the A. fumigatus and C. neoformans cell organization that may help to find new therapeutic strategies to fight, more efficiently, against fungal infections
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Lu, Wei-Bin. "GFP-based sensing and state estimation in transgenic plant cell culture /". free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3060120.
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Fink, Alexandra [Verfasser], i Joachim [Akademischer Betreuer] Rädler. "Cell-migration in two-state micropatterns / Alexandra Fink ; Betreuer: Joachim Rädler". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1213658853/34.
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Cho, Hyoung Yeon. "A new power control strategy for hybrid fuel cell vehicles". Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-06252004-141449.
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Bae, Joong-Myeon. "Properties of selected oxide cathodes for solid oxide fuel cell". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244213.
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Chitteti, Brahmananda Reddy. "Proteome and phosphoproteome dynamic change during cell dedifferentiation in Arabidopsis thaliana". Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-07172007-035002.
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Dyantyi, Noluntu. "Factors influencing fuel cell life and a method of assessment for state of health". University of the Western Cape, 2018. http://hdl.handle.net/11394/6753.
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Philosophiae Doctor - PhDProton exchange membrane fuel cells (PEMFC) converts chemical energy from the electrochemical reaction of oxygen and hydrogen into electrical while emitting heat, oxygen depleted air (ODA) and water as by-products. The by-products have useful functions in aircrafts, such as heat that can be used for ice prevention, deoxygenated air for fire retardation and drinkable water for use on board. Consequently, the PEMFC is also studied to optimize recovery of the useful products. Despite the progress made, durability and reliability remain key challenges to the fuel cell technology. One of the reasons for this is the limited understanding of PEMFC behaviour in the aeronautic environment. The aim of this thesis was to define a comprehensive non-intrusive diagnostic technique that provides real time diagnostics on the PEMFC State of Health (SoH). The framework of the study involved determining factors that have direct influence on fuel cell life in aeronautic environment through a literature survey, examining the effects of the factors by subjecting the PEMFC to simulated conditions, establishing measurable parameters reflective of the factors and defining the diagnostic tool based on literature review and this thesis finding.
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Massaad, Michel Jean. "Mechanism of endoplasmic reticulum localization and oligomerization state of Saccharomyces cerevisiae [alpha] 1, 2-mannosidase". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84293.
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In this thesis, the mechanism of endoplasmic reticulum localization of Saccharomyces cerevisiae alpha1,2-mannosidase is studied. alpha1,2-mannosidase is a type II membrane glycoprotein localized in the endoplasmic reticulum, yet it does not have any of the known endoplasmic reticulum localization signals.Immunofluorescence studies show that the endoplasmic reticulum localization of alpha1,2-mannosidase depends on the Golgi protein Rer1p, since in rer1-deleted cells, alpha1,2-mannosidase migrates to the vacuoles. Furthermore, alpha1,2-mannosidase acquires Golgi-specific carbohydrate modification. These results show that the steady state endoplasmic reticulum localization of alpha1,2-mannosidase involves recycling from the Golgi apparatus. The transmembrane domain of alpha1,2-mannosidase is important for endoplasmic reticulum localization since fusing it to the Golgi protein Kre2p results in the endoplasmic reticulum localization of the chimera in an Rer1p-dependent manner. Mutation of the polar residues in the transmembrane domain do not affect endoplasmic reticulum localization of alpha1,2-mannosidase, nor Rer1p-dependent recycling, indicating that the polar residues are not important for these processes. alpha1,2-Mannosidase and Rer1p interact, determined using the split-ubiquitin system, a genetic method adapted to study membrane protein interactions in vivo. Therefore, the transmembrane domain of alpha1,2-mannosidase mediates recycling from the Golgi apparatus in a mechanism that involves interaction with the Golgi protein Rer1p.
When solubilized and subjected to gel filtration analysis, endogenous alpha1,2-mannosidase is eluted on Sephacryl S-200 as twice the molecular weight of the purified recombinant enzyme lacking its transmembrane domain. Immunoprecipitation studies show that alpha1,2-mannosidase can form a homodimer. Furthermore, mutation of the asparagine residue at position 3, or the tyrosine residues at positions 20 and 21, prevents dimerization.
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Ziller, Michael [Verfasser], i Oliver [Akademischer Betreuer] Kohlbacher. "Dissecting cellular states and cell state transitions through integrative analysis of epigenetic dynamics / Michael Ziller ; Betreuer: Oliver Kohlbacher". Tübingen : Universitätsbibliothek Tübingen, 2014. http://d-nb.info/1163236950/34.
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Wilson, Gillian Mary. "High frequency dielectric studies of cell suspensions using time domain reflectometry". Thesis, Bangor University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305946.
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Xi, He. "Pluripotency state affects the mechanical phenotype of the embryonic stem cell nucleus". Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/31796.
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The thesis aims at investigating the connection between nucleus mechanical characteristics with pluripotency state and differentiation associated with altered cell gene expression levels. The project investigates the deformation characteristics of the cell nucleus during unconfined compression in a 3D cell-seeded agarose constructs. The studies report modification in the mechanical behaviour of the nucleus in different embryonic stem cell phenotypes based on various pluripotent states (naïve or primed states) or following triggering of early differentiation. A multi-scale model is also presented to simulate dynamic details of mechanical perturbation to cells during compression. The first chapter presents a review of the relevant literature to introduce current progress in the related research field and the second chapter describes the general methods used in the thesis including cell culture, agarose construct preparation, construct compression and microscopy recording. The third chapter presents findings of studies involving the application of compression to embryonic stem cells in naïve and primed sate within agarose scaffolds. A range of parameters relating to the relative cell/nucleus morphological modifications are recorded with analysis and discussion. Chapter four presents studies that investigate the early differentiation of embryonic stem cells from either the naïve and primed pluripotency, achieved by altering cell culture condition, and further reveals the nuclear mechanical characteristic changes. The fifth chapter describes a multi-scale model developed to simulating the 3D cell-seeded agarose compression reported in previous chapters. This model is also used to estimate cell mechanical parameters and show accurate deformation detail in different locations within the construct. A final discussion of the thesis is provided in chapter 6 with a plan for future work.
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Somers, Sachin J. "The phosphorylation state of Saccharomyces cerevisiae linker histone Hho 1p during entry and exit of stationary phase". Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/4335.
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Includes bibliographical references.Our group has recently found that the linker histone Hh01 p of Saccharomyces cerevisiae exhibited a significant increase in binding to chromatin during stationary phase. Because of the role of H1 in gene expression and chromatin compaction, it is essential to understand the mechanism behind this change in binding behaviour for a complete mechanistic description of gene regulation. We postulated that the phosphorylation of serine or threonine residues decrease the affinity of H1 for DNA, resulting in the dissociation of H1 from chromatin in exponential phase. We investigated this possible change in the phosphorylation state of Hh01 p in yeast cells in exponential phase and in stationary phase by immunoprecipitation of Hh01 p, followed by western analysis using antiphosphoserine and anti-phosphothreonine antibodies.
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Simmons, Michelle Yvonne. "The characterisation of CdTe-based epitaxial solar cell structures fabricated by MOVPE". Thesis, Durham University, 1992. http://etheses.dur.ac.uk/1498/.
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Angelidis, Ilias [Verfasser], i Jürgen [Akademischer Betreuer] Behr. "Single cell transcriptomic mapping of cell state identities in lung aging, injury and repair / Ilias Angelidis ; Betreuer: Jürgen Behr". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/1236502213/34.
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Garg, Himanshu. "Feline Immunodeficiency Virus (FIV) Envelope Glycoprotein-Mediated Cell Fusion and Apoptosis". NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-11042003-141554/.
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Feline Immunodeficiency Virus (FIV) and Human Immunodeficiency Virus (HIV) are lentiviruses that are remarkable similar in their genomic organization, receptor usage and pathogenesis. Based on this FIV has evolved into a well-established small animal model for studying AIDS. FIV and HIV cause a progressive depletion of T cells via a still unknown mechanism though numerous studies support a role of membrane expressed HIV env glycoprotein in apoptotic killing of CD4+ T cells. HIV env glycoprotein is a heterodimer of surface expressed gp120 that binds to CD4 and a chemokine receptor and transmembrane gp41 that mediates fusion and syncytia formation. The role of the fusion process in HIV env-mediated apoptosis remains controversial even though evidence suggests that cytopathic effect of HIV is related to the fusogenic potential of env glycoprotein. Blocking HIV env receptor interactions either at the level of gp120 or gp41 blocks both syncytia formation and apoptosis. This suggests a crucial role for HIV gp41 in fusion, as well as apoptosis. The hydrophobic pre-transmembrane (pre-TM) region of HIV gp41 is important for membrane fusion and sequence analysis reveals a similar region in FIV gp41. The current study was undertaken to determine the role of different regions of FIV env in mediating fusion and apoptosis in bystander cells and to determine whether the two phenomena are related. FIV env interactions with target cells were blocked at the level of gp120 or gp41 and the effect of these on fusion and apoptosis studied. The role of FIV gp41 pre-TM region in fusion and apoptosis was also determined. Our findings support a role of FIV env in apoptotic loss of T cells and this phenomenon correlates with env-mediated fusion.
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Barr, Maggie Jeanne. "Flow Cytometric Analyses on the Activation, Proliferation, and Differentiation State of B Cells in Rainbow Trout (Oncorhynchus mykiss)". W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539626896.
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Sly, Jonathan L. "High-pressure optical studies of III-V semiconductors using the diamond anvil cell". Thesis, University of Surrey, 1995. http://epubs.surrey.ac.uk/843077/.
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High pressure photoluminescence techniques have been used to investigate bulk and heterostructure properties in a number of III-V semiconductor materials systems. The results are reported in this thesis along with a description of the experimental procedures. The indirect band-gaps of a series of InxGa1-xSb/GaSb quantum-wells have been measured. The results have been extrapolated to zero indium content to give the indirect band-gaps of bulk GaSb; values quoted in the literature vary widely. We obtain results consistent with accepted values but cannot refine them due to experimental errors arising from using ruby as a pressure gauge. A development of the experimental technique is proposed which would eliminate this source of error. The low-temperature F and X band-gaps have been determined in bulk (AlxGa1-x)0.5In0.5P functions of composition; we obtain E8(T)=(1.985+0.61x)eV and E8(X)=(2.282+0.085x)eV respectively. Lower limits have been put on the position of the L minima in this system and 1% compressively strained Ga0.38,In0.62P. Band offsets have been determined in unstrained (y=0.5) and 1% (y=0.62) compressively strained Ga1-yInyP/(AlxGa1-x)0.5 In0.5P; we obtain Ev(meV)=63x+157x2 and Ec(meV)=547x-157x2 for the unstrained system and Ev(meV)=72+63x+157x2 and Ec(meV)=72+547x-157x2 for the strained system. Effects of atomic ordering on the conduction band of Ga0.5In0.5P have been investigated. An investigation of anomalous pressure coefficients in strained InxGa1-x As has been carried out. A strain-related reduction in pressure coefficients (similar to that reported for InxGa1-xAs/GaAs) is found in In0.67Ga0.33As/InGaAsP quantum-wells grown on [001] substrates, but not in InGaAs/GaAs grown on [111] substrates. Preliminary results from tensile samples show evidence of increased pressure coefficients. A new X-ray powder-diffraction technique is described for direct investigation of the elastic behaviour of strained InGaAs.
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Miyahara, Ryo. "Expression of neural cell adhesion molecules(polysialated form of neural cell adhesion molecule and L1-cell adhesion molecule)on resected small cell lung cancer specimens : in relation to proliferation state". Kyoto University, 2001. http://hdl.handle.net/2433/150163.
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Onysko, Kira Alison. "Unsteady-state behaviour of an immobilized-cell fluidized-bed bioreactor for phenol biodegradation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ38260.pdf.
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Mazza, Luan Carlos dos Santos. "Single phase bidirectional DAB DC-DC converter based on three state switching cell". Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14412.
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This work presented is DC-DC isolated ZVS Bidirectional Dual Active Bridge (DAB) single phase converter, based three-state switching cell is presented. The proposal is to apply it in photovoltaic systems with battery bank into smart networks. Basically the drive control is the duty cycle (D) of the switches and the Phase Shift (φ) of the fundamental tensions between the bridges. The gyrator modeling of the converter is presented, highlighting its natural operating characteristic as gyrator. Shows the qualitative and quantitative analysis of the converter, realizing the full study of the stages of operation of the topology and checking all sixteen regions of operation. To obtain the regions of soft-switching, the fundamental model is applied. The design procedure of the converter is presented, and the results of simulations. A 2kW prototype was developed, aimed at obtaining experimental results validate the theoretical analysisNeste trabalho à apresentado o conversor CC-CC ZVS isolado bidirecional Dual Active Bridge (DAB) monofÃsico, baseado na cÃlula de comutaÃÃo de trÃs estados. A proposta à aplicÃ-lo em sistemas fotovoltaicos com banco de baterias em redes inteligentes. Basicamente o controle do conversor consiste na razÃo cÃclica (D) dos interruptores e o Phase Shift (φ) entre as componentes fundamentais das tensÃes entre as pontes. A modelagem por gyrator do conversor à apresentada, destacando-se sua caracterÃstica natural de funcionamento como gyrator. Mostra-se a anÃlise qualitativa e quantitativa do conversor, realizando o estudo completo das etapas de operaÃÃo da topologia e verificando todas as dezesseis regiÃes de operaÃÃo. Para obtenÃÃo das regiÃes de comutaÃÃo suave, à aplicado o modelo fundamental. O procedimento de projeto do conversor à apresentado, alÃm dos resultados de simulaÃÃes. Um protÃtipo de 2 kW foi desenvolvido, visando a obtenÃÃo dos resultados experimentais e validando a anÃlise teÃrica.
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Luk, Hui Ying. "Effect of the Resistance Exercise-Induced Hormonal Changes on Satellite Cell Myogenic State". Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157528/.
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Skeletal muscle satellite cells are important for muscle repairing and muscle mass growth. For a successful muscle regenerative process, satellite cells have to sequentially undergoing different stages of myogenic process, i.e. proliferative state and differentiation state. To support this process, the presence of different circulating factors, such as immune cells, cytokines, and hormones, at the appropriate time course is critical. Among these factors, hormones, such as testosterone, cortisol, and IGF-1, have shown to play an important role in satellite cell proliferation and differentiation. Studies investigated the effect of testosterone on satellite cell using a supraphysiological dose in human or in cell culture demonstrated that testosterone is critical in satellite cell myogenic process. Due to the anabolic effect of testosterone on muscle, studies had been focused on the physiological means to increase the circulating testosterone concentration in the body to maximize the muscle mass growth from resistance exercise. The acute and transient increase in testosterone has shown to be beneficial to muscle mass growth and strength gain; however, this change in physiological testosterone concentration on satellite cell myogenesis is not known. Therefore the purpose of this dissertation is to first determine the effect of acute change in exercise-induced hormones on satellite cell myogenic state, then to determine if testosterone promotes satellite cell proliferation.
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Holl, Mark Roland. "Dynamic analysis, measurement, and control of cell growth in solid state polymeric foams /". Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/7120.
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Pofahl, Martin [Verfasser]. "State-dependent processing of Dentate Gyrus granule cell activity in-vivo / Martin Pofahl". Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1224966104/34.
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Kudrimoti, Hemant Shashikant. "Reactivation of hippocampal cell assemblies: Effects of behavioral state, experience and EEG dynamics". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284692.
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During slow-wave sleep (SWS), traces of neuronal activity patterns from preceding behavior can be observed in rat hippocampus and neocortex. The spontaneous reactivation of these patterns is manifested as the reinstatement of the distribution of pairwise firing rate correlations within a population of simultaneously recorded neurons. The effects of behavioral state (quiet wakefulness, SWS and REM), interactions between two successive spatial experiences, and global modulation during 200 Hz EEG "ripples" on pattern reinstatement were studied in CA1 pyramidal cell population recordings. Pairwise firing rate correlations during often repeated experiences accounted for a significant proportion of the variance in these interactions in subsequent SWS or quiet wakefulness and, to a lesser degree, during SWS prior to the experience on a given day. The latter effect was absent for novel experiences, suggesting that a persistent memory trace develops with experience. Pattern reinstatement was strongest during sharp wave-ripple oscillations, suggesting that these events may reflect system convergence onto attractor states corresponding to previous experiences. When two different experiences occurred in succession, the statistically independent effects of both were evident in subsequent SWS. Thus, the patterns of neural activity reemerge spontaneously, and in an interleaved fashion, and do not necessarily reflect persistence of an active memory (i.e., reverberation). Firing rate correlations during REM sleep were not related to the preceding familiar experience, possibly as a consequence of trace decay during the intervening SWS. REM episodes also did not detectably influence the correlation structure in subsequent SWS, suggesting a lack of strengthening of memory traces during REM sleep, at least in the case of familiar experiences.