Littérature scientifique sur le sujet « Etat cellulaire »
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Articles de revues sur le sujet "Etat cellulaire"
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Clément, O. « 1305 Imagerie cellulaire : etat actuel et perspectives ». Journal de Radiologie 85, no 9 (septembre 2004) : 1169. http://dx.doi.org/10.1016/s0221-0363(04)76529-4.
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Li, Long, Mushuang Hu, Long Zheng, Chao Zhang, Jiawei Li, Ruiming Rong, Tongyu Zhu et Yichen Jia. « Endothelin Receptor Down-Regulation Mediated Ligand Regulation Mechanisms Protect Against Cellular Hypoxia Injury in Rat Vascular Endothelial Cells ». Cellular Physiology and Biochemistry 40, no 6 (2016) : 1443–54. http://dx.doi.org/10.1159/000453196.
Texte intégralRésumé :
Objective: Investigation of the effect of endothelin receptor A (ETaR)-targeting small interfering RNA (siRNA) on rat vascular endothelial cellular hypoxia injury, as well as its underlying mechanism. Methods: An in vitro rat vascular smooth muscle cells - endothelial cells co-culture model was established and transfected with ETaR siRNA before hypoxia treatment. Cell culture supernatant, cellular protein and RNA were collected and examined at 0.5hrs, 1hrs, 2hrs, 4hrs, 8hrs, 16hrs, 24hrs and 48hrs of hypoxia with 1% oxygen. The time point at which the best silencing effect was achieved was chosen, eNOS inhibitor L-NAME was added, and post hypoxia cell culture supernatant, cellular protein and RNA was collected for further examination. Results: After hypoxic treatment, endothelial-1 (ET-1) and ETaR expression levels gradually increased as oxygen deprivation extended. ET-1 and ETaR expression levels were significantly lower in the ETaR siRNA group compared with the Hypoxia group (P<0.001). Such difference peaked at 4hrs of hypoxia. ELISA examination of cell culture supernatant revealed that the amount of ET-1 and TGF-βin the ETaR siRNA group were significantly lower compared to the Hypoxia group at all times, while the amount of NO and eNOS was higher. After 4 hrs of hypoxia, Smad2, Smad3, HIF-1, TNF-α, IFN-γ, IL-6, MCP-1, NF-κb, ET-1 and ANG II mRNA expression in endothelial cells and ETaR mRNA expression in A-10 cells of the ETaR siRNA group were lower than those of the Hypoxia siRNA group, while such results were much higher in the L-NAME group. Western Blot results showed lower expression of ETaR in the ETaR siRNA group compared with the hypoxia and negative siRNA groups, as well as significantly higher ETaR expression in the L-NAME group compared with the ETaR siRNA group. PI3K and p-AKT expression levels were mildly elevated after mild oxygen deprivation, and ETaR siRNA was able to enhance such elevation induced by hypoxia. In the L-NAME group, PI3K and p-AKT expression was much higher than the ETaR siRNA group. PKG and sGC expression levels significantly descended after mild oxygen deprivation. While such levels were higher in the ETaR siRNA group, compared with the hypoxia and negative siRNA groups, the L-NAME group had lower levels of PKG and sGC compared with the ETaR siRNA group. Conclusion: ETaR siRNA is capable of down-regulating the expression of inflammatory and transcription factors among endothelial cells treated with hypoxia. Down-regulation of ET-1 is triggered by altered nucleus transcription factor activity through the sGC/PKG signal pathway, and results in enhanced eNOS activity through the PI3K/Akt signal pathway. We suspect this to be the mechanism of the protective effect of ETaR siRNA.
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Swope, V. B., Z. A. Abdel-Malek, D. N. Sauder et J. J. Nordlund. « A new role for epidermal cell-derived thymocyte activating factor/IL-1 as an antagonist for distinct epidermal cell function. » Journal of Immunology 142, no 6 (15 mars 1989) : 1943–49. http://dx.doi.org/10.4049/jimmunol.142.6.1943.
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Abstract It is known that many immunologic responses to IL-1 are antagonized by the neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH). This led us to investigate the possible reciprocal effects of IL-1 and the functionally related epidermal cytokines, epidermal cell-derived thymocyte activating factor (ETAF) and IL-6, on the melanogenic effect of alpha-MSH on murine Cloudman melanoma cells. When these cells were treated with ETAF in combination with alpha-MSH or its potent analog [Nle4,D-Phe7]-alpha-MSH, the melanotropin induced increase in tyrosinase activity, and thus melanin synthesis, was abrogated. This inhibitory effect of ETAF was not mediated by competitive binding to the melanotropin receptor, because ETAF also blocked the melanogenic response of melanoma cells to isobutyl methylxanthine (IBMX) and to PGE1 and PGE2. ETAF had no effect on cellular proliferation. Inhibition of the stimulated tyrosinase activity by ETAF was not due to diminished cAMP synthesis or increased cAMP degradation. Cells treated concomitantly with ETAF and alpha-MSH, IBMX, or PGE1 had the same cAMP levels as cells treated with alpha-MSH, IBMX, or PGE1 alone. In contrast to ETAF, human rIL-1 alpha or IL-1 beta alone or in combination did not have an inhibitory effect on melanogenesis. IL-6 significantly inhibited the basal level of tyrosinase and partially abrogated the alpha-MSH-induced tyrosinase activity. IL-6 also stimulated cellular proliferation when added alone or in combination with alpha-MSH. Granulocyte-macrophage colony stimulating factor (GM-CSF) did not alter either the tyrosinase activity or cellular replication at the concentrations tested. IL-1 alpha, GM-CSF, and IL-6 or IL-1 alpha and GM-CSF added together did not significantly affect the MSH-induced tyrosinase activity. These results ascribe a new potential function for ETAF and IL-6 as modulators of the melanogenic response of pigment cells.
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Shirato, Ken, Jun Takanari, Junetsu Ogasawara, Takuya Sakurai, Kazuhiko Imaizumi, Hideki Ohno et Takako Kizaki. « Enzyme-Treated Asparagus Extract Attenuates Hydrogen Peroxide-Induced Matrix Metalloproteinase-9 Expression in Murine Skin Fibroblast L929 Cells ». Natural Product Communications 11, no 5 (mai 2016) : 1934578X1601100. http://dx.doi.org/10.1177/1934578x1601100532.
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Enzyme-treated asparagus extract (ETAS) exerts a wide variety of beneficial biological actions including facilitating anti-cortisol stress and neurological anti-aging responses. However, the anti-skin aging effects of ETAS remain to be elucidated. Reactive oxygen species (ROS) play pivotal roles in skin aging. Increased ROS levels in fibroblasts in response to ultraviolet irradiation activate c-Jun N-terminal kinase (JNK) and its downstream transcription factor activator protein-1 (AP-1), and the resultant gene expression of matrix metalloproteinase (MMP) isoforms accelerates collagen breakdown in the dermis. Therefore, we explored whether ETAS has anti-skin aging effects by attenuating the oxidative stress responses in fibroblasts. Simultaneous treatment of murine skin L929 fibroblasts with hydrogen peroxide (H2O2) and either ETAS or dextrin showed that ETAS significantly suppressed H2O2-induced expression of MMP-9 mRNA as measured by real-time polymerase chain reaction. ETAS also clearly suppressed H2O2-stimulated phosphorylation of c-Jun (AP-1 subunit) and JNK as determined by Western blot. However, ETAS did not affect the increased amounts of carbonyl proteins in response to H2O2, also as determined by Western blotting. These results suggest that ETAS diminishes cellular responsiveness to ROS but does not scavenge ROS. Thus, ETAS has the potential to prevent skin aging through attenuating the oxidative stress responses in dermal fibroblasts.
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Ogasawara, Junetsu, Tomohiro Ito, Koji Wakame, Kentaro Kitadate, Takuya Sakurai, Shogo Sato, Yoshinaga Ishibashi et al. « ETAS, an Enzyme-treated Asparagus Extract, Attenuates Amyloid β-Induced Cellular Disorder in PC 12 Cells ». Natural Product Communications 9, no 4 (avril 2014) : 1934578X1400900. http://dx.doi.org/10.1177/1934578x1400900435.
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One of the pathological characterizations of Alzheimer's disease (AD) is the deposition of amyloid beta peptide (Aβ) in cerebral cortical cells. The deposition of Aβ in neuronal cells leads to an increase in the production of free radicals that are typified by reactive oxygen species (ROS), thereby inducing cell death. A growing body of evidence now suggests that several plant-derived food ingredients are capable of scavenging ROS in mammalian cells. The purpose of the present study was to investigate whether enzyme-treated asparagus extract (ETAS), which is rich in antioxidants, is one of these ingredients. The pre-incubation of differentiated PC 12 cells with ETAS significantly recovered Aβ-induced reduction of cell viability, which was accompanied by reduced levels of ROS. These results suggest that ETAS may be one of the functional food ingredients with anti-oxidative capacity to help prevent AD.
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Agustiningsih, Agustiningsih, Muhammad Rezki Rasyak, Turyadi, Sri Jayanti et Caecilia Sukowati. « The oncogenic role of hepatitis B virus X gene in hepatocarcinogenesis : recent updates ». Exploration of Targeted Anti-tumor Therapy 5, no 1 (20 février 2024) : 120–34. http://dx.doi.org/10.37349/etat.2024.00209.
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Hepatocellular carcinoma (HCC) is the most prevalent form of primary liver cancers with high mortality rate. Among its various etiological factors, one of the major risk factors for HCC is a chronic infection of hepatitis B virus (HBV). HBV X protein (HBx) has been identified to play an important role in the HBV-induced HCC pathogenesis since it may interfere with several key regulators of many cellular processes. HBx localization within the cells may be beneficial to HBx multiple functions at different phases of HBV infection and associated hepatocarcinogenesis. HBx as a regulatory protein modulates cellular transcription, molecular signal transduction, cell cycle, apoptosis, autophagy, protein degradation pathways, and host genetic stability via interaction with various factors, including its association with various non-coding RNAs. A better understanding on the regulatory mechanism of HBx on various characteristics of HCC would provide an overall picture of HBV-associated HCC. This article addresses recent data on HBx role in the HBV-associated hepatocarcinogenesis.
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Bagnato, Anna, Francesca Spinella et Laura Rosanò. « Emerging role of the endothelin axis in ovarian tumor progression ». Endocrine-Related Cancer 12, no 4 (décembre 2005) : 761–72. http://dx.doi.org/10.1677/erc.1.01077.
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Ovarian cancer is the leading cause of gynecologic cancer-related deaths. The endothelin (ET) axis, which includes ET-1, ET-2, ET-3, and the ET receptors, ETAR and ETBR, represents a novel target in tumor treatment. ET-1 may directly contribute to tumor growth and indirectly modulate tumor–host interactions in various tumors such as prostatic, ovarian, renal, pulmonary, colorectal, cervical, breast carcinoma, Kaposi’s sarcoma, brain tumors and melanoma. Extensive experimental evidence links ETAR overexpression with tumor progression in ovarian cancer. ETAR engagement can in fact activate multiple signal transduction pathways including protein kinase C, phosphati-dylinositol 3-kinase, mitogen-activated protein kinase and transactivate epidermal growth factor receptor, which play a role in ovarian tumor growth and invasion. The effects of ETAR signaling are wide ranging and involve both cancer cells and their surrounding stroma, including the vasculature. Upon being activated, the ETAR mediates multiple tumor-promoting activities, including enhanced cell proliferation, escape from apoptosis, angiogenesis, epithelial–mesenchymal transition and increased motility and invasiveness. These findings indicate that activation of ETAR by ET-1 is a key mechanism in the cellular signaling network promoting ovarian cancer growth and progression. The predominant role played by ETAR in cancer has led to the development of small molecules that antagonize the binding of ET-1 to ETAR. The emerging preclinical data presented here provide a rationale for the clinical evaluation of these molecules in which targeting the related signaling cascade via ETAR blockade may be advantageous in the treatment of advanced stage ovarian carcinoma.
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Ward, Carol, James Meehan, Mark E. Gray, Alan F. Murray, David J. Argyle, Ian H. Kunkler et Simon P. Langdon. « The impact of tumour pH on cancer progression : strategies for clinical intervention ». Exploration of Targeted Anti-tumor Therapy 1, no 2 (9 avril 2020) : 71–100. http://dx.doi.org/10.37349/etat.2020.00005.
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Dysregulation of cellular pH is frequent in solid tumours and provides potential opportunities for therapeutic intervention. The acidic microenvironment within a tumour can promote migration, invasion and metastasis of cancer cells through a variety of mechanisms. Pathways associated with the control of intracellular pH that are under consideration for intervention include carbonic anhydrase IX, the monocarboxylate transporters (MCT, MCT1 and MCT4), the vacuolar-type H+-ATPase proton pump, and the sodium-hydrogen exchanger 1. This review will describe progress in the development of inhibitors to these targets.
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Zhang, Tie Jun, I. M. Manhrawy, A. A. Abdo, A. A. Abd El-Latif et R. Rhouma. « Cryptanalysis of Elementary Cellular Automata Based Image Encryption ». Advanced Materials Research 981 (juillet 2014) : 372–75. http://dx.doi.org/10.4028/www.scientific.net/amr.981.372.
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An image encryption based on elementary cellular automata was proposed in [Yu Xiao yang etal., International Journal of Security and Its Applications Vol.7, No.5 (2013), pp.397-406.]. In this paper, we analyze the security weaknesses of their algorithm. Based on the given analysis, it is demonstrated that the scheme under study can be broken by various attacks (Chosen Plaintext and Chosen ciphertext attacks).
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Sun, Yun, Wen-Jiang Zheng, Yong-Hua Hu, Bo-Guang Sun et Li Sun. « Edwardsiella tarda Eta1, anIn Vivo-Induced Antigen That Is Involved in Host Infection ». Infection and Immunity 80, no 8 (14 mai 2012) : 2948–55. http://dx.doi.org/10.1128/iai.00063-12.
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ABSTRACTEdwardsiella tarda, a Gram-negative bacterium, is a severe fish pathogen that can also infect humans. In this study, we identified, viain vivo-induced antigen technology, anE. tardaantigen, Eta1, and analyzed its function in a Japanese flounder (Paralichthys olivaceus) model. Eta1 is composed of 226 residues and shares homology with putative bacterial adhesins. Quantitative real-time reverse transcriptase (RT)-PCR analysis indicated that when culturedin vitro,eta1expression was growth phase dependent and reached maximum at mid-logarithmic phase. During infection of flounder lymphocytes,eta1expression was drastically increased at the early stage of infection. Compared to the wild type, theeta1-defective mutant, TXeta1, was unaffected in growth but exhibited attenuated overall virulence, reduced tissue dissemination and colonization capacity, and impaired ability to invade flounder lymphocytes and to block the immune response of host cells. The lost virulence of TXeta1 was restored when a functionaleta1gene was reintroduced into the strain. Western blot and immunodetection analyses showed that Eta1 is localized to the outer membrane and exposed on the surface ofE. tardaand that recombinant Eta1 (rEta1) was able to interact with flounder lymphocytes. Consistent with these observations, antibody blocking of Eta1 inhibitedE. tardainfection at the cellular level. Furthermore, when used as a subunit vaccine, rEta1 induced strong protective immunity in flounder against lethalE. tardachallenge. Taken together, these results indicate that Eta1 is anin vivo-induced antigen that mediates pathogen-host interaction and, as a result, is required for optimal bacterial infection.
Thèses sur le sujet "Etat cellulaire"
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Sanchez, Gonzalez Yuriana. « Etude de l’adaptation et de la gestion de l’activité cellulaire dans un bioréacteur biétagé : intensification de la production d’éthanol ». Toulouse, INSA, 2008. http://eprint.insa-toulouse.fr/archive/00000247/.
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L’objectif des travaux est de comprendre et quantifier comment gérer l’activité cellulaire de la levure Saccharomyces cerevisiae afin d’intensifier les productions microbiennes (spécifiquement la production d’éthanol biocarburant) dans un Bioréacteur Biétagé avec Recyclage cellulaire (BBRC) en mode continu. En effet, les performances globales du procédé sont directement affectées par le maintien de l’activité cellulaire et notre étude cible la quantification du comportement de la levure en fonction de son état physiologique et lorsqu’elle est soumise à des changements d’environnement caractérisés par différents concentrations en éthanol (plus ou moins permissives vis-à-vis du métabolisme microbien). Les travaux expérimentaux sont divisés en deux parties : des expériences en mode discontinu et discontinu alimenté, appelées « ex-situ » où sont analysées les réponses dynamiques des cellules (mode et intensité) par l’intégration des donnés macrocinétiques et microscopiques dans des conditions de culture parfaitement contrôlées et maîtrisées découplant le rôle de l’état physiologique initial des levures sur leurs performances futures et celui de l’éthanol, connu pour son caractère inhibiteur. Sur la base de ces résultats, un modèle mathématique dynamique est proposé et validé sur des expériences indépendantes pour décrire la réponse dynamique du microorganisme en termes des vitesses spécifiques de croissance et de production d’éthanol lors de changement de conditions environnementales. Cette étude montre que l’activité de la levure est certes dépendante du degré d’inhibition dû à l’éthanol dans le milieu de culture mais quantifie de manière plus innovante l’impact de la « mémoire » de la levure et le rôle de l’état physiologique des cellules pour atteindre des performances optimales. Ces paramètres définiront les temps d’adaptation nécessaires pour la reprise et/ou le maintien des activités catalytiques ou de la viabilité cellulaire. La deuxième partie est l’application en BBRC des conditions opératoires et environnementales optimales dégagées des résultats « ex-situ » afin d’optimiser le fonctionnement du procédé en prenant en compte les temps d’adaptation de la cellule lors des recyclages de la biomasse. L’analyse des résultats expérimentaux a permis d’identifier d’autres paramètres qui, au-delà de l’éthanol, affecteraient l’activité cellulaire dans ce procédé intensif. Ainsi, les rôles de la pression osmotique et du ratio des temps de séjour biomasse dans le premier et le deuxième étage (TB1/TB2) sont de nouvelles pistes d’investigation pour une meilleure maîtrise de ce bioréacteur innovant visant à atteindre de hautes productions et productivités par voie microbienne
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Tournebize, Juliana. « Synthèse de nanoparticules d'or fonctionnalisées par l'acide dihydrolipoïque : caractérisation, étude de stabilité et impact sur l'homéostasie redox cellulaire ». Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0030/document.
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L'objectif de notre travail consiste en la conception de nanoparticules d'or (AuNP) monodisperses, et stables ; puis en l'évaluation de l'effet des propriétés de surface de AuNP sur leur internalisation et leur toxicité dans une lignée cellulaire (macrophages alvéolaires de rat-NR8383). Nous avons synthétisé des NP d'or soit stabilisées par les ions citrate (Au-citrate) soit fonctionnalisées par l'acide dihydrolipoïque (DHLA) (NP Au@DHLA). Nous avons montré que la densité de couverture est un paramètre crucial pour améliorer la stabilité colloïdale des AuNP dans des conditions physiologiques. Nous avons caractérisé complètement les AuNP d'un point de vue physico-chimique, en particulier en développant une méthode de dosage spectrophotocolorimétrique de l'or. Nous avons aussi étudié les effets biologiques des AuNP. Tout d'abord, en absence de cellules, nos résultats révèlent que la fonctionnalisation de surface de AuNP affecte la réactivité avec des biomolécules tels que le glutathion réduit (GSH), le S-nitrosoglutathion, et l'albumine de sérum bovin (les Au-citrate interagissant avec toutes les molécules testées), l'internalisation par les cellules (les Au-citrate sont deux fois plus internalisées) et l'état redox cellulaire (les Au-citrate diminuent de 20% le niveau intracellulaire de GSH) sans relation apparente avec la formation de ROS. En outre, les AuNP ne semblent pas induire l'expression des mRNA associées à la réponse inflammatoire (tnf), au stress oxydant (ncf1) et à l'apoptose (nfkb2), paramètres essentiels pour préserver l'intégrité de la cellule et de l'organisme, et envisager l'utilisation de ces NP comme plateforme pharmaceutiqueThe aim of our work was to produce highly monodisperse and stable gold nanoparticles (AuNP) with potential for biomedical applications, and to evaluate the effect of AuNP surface properties on their uptake and cytotoxicity in a cultured cell line (rat-alveolar macrophages-NR8383). We synthesized AuNP either stabilized with citrate (Au-citratte) or capped with a dithiol, i.e. dihydrolipoic acid (Au@DHLA NP). The present study shows that the surface packing density is a crucial parameter to enhance the colloidal stability of AuNP in physiological conditions. We fully characterized the considered AuNP from a physico-chemical point of view. Indeed, we optimized a spectrocolorimetric and a HPLC method to evaluate the properties of AuNP. We studied the biological effects of AuNP. Under cell-free conditions, our results reveal that AuNP coating affects their reactivity with biomolecules, i.e. reduced glutathione (GSH), S-nitrosoglutathione and bovine serum albumin (Au-citrate interact with all molecules), the cellular uptake (Au-citrate are two times more effective) and redox status (Au-citrate decrease the intracellular GSH level by ca 20%) with no apparent relationship with ROS formation. Furthermore, both AuNP appear not to induce mRNA expression related to inflammatory response (tnfa), oxidative stress (ncf1) and apoptosis (nfkb2), parameters of main importance to preserve cellular integrity and body safety, and to assure pharmaceutical platform function
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Molle, Boris. « Etude des propriétés dynamiques de structures cellulaires formées dans un système eau/huile/surfactant/alcool ». Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10249.
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Dans cette these sont etudiees les proprietes dynamiques d'un systeme eau/toluene/sds/butanol qui forme spontanement des structures de type cellulaire a l'echelle nanoscopique, ou l'huile est confinee dans des cellules polyedriques separees par un film d'eau. A temperature ambiante le systeme est liquide et l'arrangement des cellules est macroscopiquement desordonne. Lorsque la temperature augmente le systeme devient viscoelastique et forme des structures cellulaires cristallines cubiques. La combinaison de differentes techniques experimentales a permis d'explorer la dynamique a differentes echelles d'espace (1 nm a 1 m) et de temps (1 ns a 100 s). Il en resulte une image complete de la dynamique dans ces structures cellulaires. La spectroscopie par echo de spin neutron (nse) a permis de sonder ces systemes a l'echelle locale de la cellule. Elle met en evidence que les cellules sont soumises a des fluctuations de forme. L'analyse des donnees fait de plus apparaitre un processus diffusif qui est attribue a des fluctuations de position des cellules dans la cage formee par leurs voisines. Une augmentation significative de la dynamique des fluctuations des cellules est observee lorsque le reseau cellulaire s'ordonne. Ce comportement nous a permis de preciser le role de ces fluctuations dans la stabilite de ces structures. L'etude par diffusion dynamique de la lumiere (dls) fait apparaitre deux modes diffusifs bien distincts. Le mode rapide correspond a un processus de compression-dilatation du reseau cellulaire. Ce processus a pour origine la nature dynamique de la structure a l'echelle de la cellule (mise en evidence par nse). Le coefficient de diffusion du mode lent et celui du sds mesure par diffusion rmn decrivent un meme processus diffusif qui correspond a une diffusion macroscopique des cellules. L'existence de ce processus diffusif dans le domaine cubique permet de rendre compte des proprietes viscoelastiques des structures cellulaires cubiques.
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Leclercq, Pascale. « Etat infectieux et métabolisme des hydrates de carbone : études in vitro sur hépatocytes isolés et in vivo chez des patients infectés par le VIH ». Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10122.
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Le sepsis induit une inhibition de la neoglucogenese (ngg). Modele experimental : sepsis de gravite moderee chez des rats traites par endotoxine avec preparation d'hepatocytes isoles et technique de perfusion. Localisation du niveau et des mecanismes de l'inhibition. Inhibition au niveau du cycle pyruvatephosphoenolpyruvate sans modification de la pyruvate kinase (role de la pepck). Pas d'alteration du cycle des fructoses par le sepsis ; possible inhibition du cycle des glucoses (inhibition de la glucose-6-phosphatase). Etude de la ngg a partir du glycerol (independante de la pepck et fonction du potentiel redox cellulaire) : inhibition avec accumulation de glycerol-3-phosphate (g3p) d'ou activation de la voie de la glycerol-3-phosphate deshydrogenase mitochondriale (navette g3p/dhap) et modification du potentiel redox. Sepsis : augmentation du volume cellulaire independante des substrats qui agit comme second messager sur le metabolisme hepatocytaire. Pas de modification de l'etat energetique cellulaire dans ce sepsis de gravite moderee. Resume des modifications induites par le sepsis : par le biais des cytokines et du no comme messager intracellulaire, induction d'un gonflement cellulaire (modification des transporteurs ?) puis modifications enzymatiques : inhibition de la pepck. Dans le cas du glycerol, c'est l'accumulation du glycerol-3-phosphate qui est responsable de l'inhibition de la ngg. 2eme partie : modifications metaboliques chez le patient infecte par le vih protocole experimental associant une etude du metabolisme du lactate et une mesure par calorimetrie indirecte de la depense energetique de repos (der) et celle induite par le test d'hyperlactatemie (patients vih et controles). Mesures de der : les patients vih en phase stable ne sont pas hypermetaboliques. Pas de modification du metabolisme du lactate (demi-vie, clairance, production endogene) chez les vih. Insulino-sensibilite avec moindre elevation de la glycemie chez les malades.
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Meyer, Swann. « Molecular characterization of aggressive cell states in pediatric gliomas and sarcomas ». Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10364.
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Bien que considérés comme des maladies rares, les cancers pédiatriques sont la 2e cause de mortalité chez les enfants de moins de 14 ans dans les pays occidentaux. Des progrès considérables ont été réalisés dans les années 1970, avec une survie globale de 70% atteinte en une vingtaine d’années. Néanmoins, certains sous-groupes sont toujours associés à un pronostic sévère, et la question des séquelles dues aux traitements demeure. Ces défis proviennent notamment du fait que la majorité des traitements des cancers pédiatriques ont initialement été développés pour des cancers de l’adulte, alors que l’on sait aujourd’hui qu’ils présentent des particularités, notamment sur le plan biologique. Il est donc important d’identifier les spécificités des cancers pédiatriques pour mieux cibler leurs vulnérabilités. Les travaux de cette thèse ont ainsi porté sur la caractérisation bioinformatique des aspects moléculaires impliqués dans l’agressivité tumorale de deux types de tumeurs pédiatriques : les gliomes diffus de la ligne médiane (DMG) et les rhabdomyosarcomes (RMS). Nous avons identifié des signalisations oncogéniques impliquées dans l’acquisition d’un phénotype invasif dans ces cancers, et caractérisé un nouveau facteur individuel susceptible de jouer un rôle pronostique dans les RMS. Enfin, ces études sont conclues par des réflexions épistémologiques sur le rôle des technologies multi-omiques, ces dernières ayant été centrales tout au long de ces travauxAlthough considered a rare disease, pediatric cancers are the 2nd leading cause of death in children under the age of 14 in Western countries. Considerable progress was made in the 1970s, with an overall survival of 70% achieved in around twenty years. Nevertheless, certain subgroups are still associated with a poor prognosis, and the matter of treatment-related sequelae remains. These challenges partly stem from the fact that the majority of treatments for pediatric cancers were initially developed for adult cancers, even though we now know that they have their own particularities, notably in terms of biology. It is therefore important to identify the specificities of pediatric cancers to better target their vulnerabilities. The work of this thesis focused on the bioinformatic characterization of the molecular components involved in tumor aggressiveness, in two types of pediatric tumors: diffuse midline gliomas (DMG) and rhabdomyosarcomas (RMS). In both cases, we identified oncogenic signals involved in the acquisition of an invasive phenotype, and highlighted a new individual factor likely to play a prognostic role in RMS. Lastly, these studies are concluded by epistemological reflections on the role of multi-omics technologies in oncology, which have been central throughout this work
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Joux, Fabien. « Dynamique des etats physiologiques des populations bacteriennes en eau de mer : approche cellulaire en conditions de survie ». Paris 6, 1997. http://www.theses.fr/1997PA066396.
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Les objectifs de ce travail ont ete d'analyser l'heterogeneite et la dynamique des etats physiologiques au sein (1) de populations bacteriennes soumises a differentes conditions de stress, en choisissant un modele de bacterie allochtone au milieu marin (salmonella typhimurium) et differentes bacteries marines (deleya aquamarina, alteromonas haloplanktis, vibrio fischeri, vibrio sp. ), et (2) des communautes naturelles. Pour repondre a ces objectifs, differents protocoles permettant l'analyse cellulaire de fonctions physiologiques et de l'adn ont ete definis. Ces analyses ont ete effectuees par cytometrie en flux et par microscopie en epifluorescence en utilisant des marqueurs fluorescents specifiques. Dans le cas des experimentations concernant l'espece s. Typhimurium, les cellules ont ete soumises a un double stress osmotique et nutritionnel. Ces experimentations ont mis en evidence (1) une succession d'etats cellulaires en cours de survie, suggerant une alteration progressive de la physiologie des cellules, (2) un comportement particulier (lyse apparente) ou non (perte de la cultivabilite) en relation avec le contenu en adn des cellules, (3) une incapacite des cellules non cultivables a retrouver une activite de reproduction. Dans le cas des experimentations concernant les especes de bacteries autochtones au milieu marin, les cellules ont ete soumises au stress unique de la carence nutritionnelle. Les resultats ont montre que la dynamique des etats cellulaires est variable en fonction de l'espece et que l'etat actif mais non cultivable, lorsqu'il est observe, semble etre associe a une forme de senescence. Enfin, nous avons entrepris l'etude de l'heterogeneite des etats cellulaires au sein des communautes naturelles marines. Ce travail a donne lieu notamment a l'optimisation d'une technique permettant l'analyse de l'activite potentielle de syntheses metaboliques. Differents etats cellulaires sont decrits et leurs implications ecologiques sont commentees.
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Lebrun, Marie-Monique. « Instabilites cellulaires en solidification directionnelle : experiences en couches minces ». Paris 7, 1987. http://www.theses.fr/1987PA077013.
Texte intégralRésumé :
Etude de l'apparition d'instabilites morphologiques a l'interface liquide-solide dans des echantillons minces d'un corps transparent (tetrabromomethane avec quelques pour mille d'impuretes). Observation en direct a l'aide d'un microscope optique d'une camera video, ce qui donne acces a la dynamique de solidification
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Amillastre, Emilie. « Amélioration de la robustesse de souches de levures aux stress technologiques par une stratégie de génie microbiologique : Application à la production industrielle de bio-éthanol à partir de matières premières agricoles ». Thesis, Toulouse, INSA, 2012. http://www.theses.fr/2012ISAT0058/document.
Texte intégralRésumé :
Sous contraintes industrielles, les micro-organismes sont soumis à différents stress technologiques, liés à leur culture en réacteur de grande taille, altérant leur viabilité et les performances des procédés. Les fluctuations des paramètres physico-chimiques (température, pH, …) sont responsables de cette baisse d’efficacité de la fermentation. Afin de contribuer à l’intensification des performances des procédés de production de bio-éthanol, ce projet de thèse propose d’améliorer la robustesse d’une souche industrielle de Saccharomyces cerevisiae productrice d’alcool vis-à-vis d’un stress environnemental : la température. La stratégie générale de ce projet réside dans l’obtention d’un mutant plus tolérant que la souche sauvage au stress appliqué par abaissement de son taux de décès. Un pilote original de culture en continu a été mis en place, couplant mutagénèse aux UV, générant des modifications génétiques et pression de sélection par des variations de température, permettant la sélection des variants les plus robustes. Un modèle phénoménologique a été développé afin de simuler les cinétiques microbiennes selon le mode de conduite du pilote et d’optimiser les conditions de fonctionnement nécessaires à l’obtention des futurs variants. Ce modèle cinétique fait intervenir l’influence de la température sur les cinétiques de croissance, de décès cellulaire et de production d’éthanol chez Saccharomyces cerevisiae. Ces cinétiques ont été quantifiées expérimentalement en fonction de la température et des traitements de mutagénèse par UV. Grâce aux conditions obtenues par simulation, des cultures en mode continu ont été réalisées et des variants obtenus ont été caractérisés, en condition de production intensive d’éthanol, sur la base de leurs performances en termes de croissance, de décès et de capacités fermentaires. Cette stratégie a permis de sélectionner un variant possédant une meilleure robustesse vis-à-vis de la température, caractérisé par un taux de décès plus faible que celui de la souche sauvage. Néanmoins ce variant ne se caractérise pas par de meilleures performances fermentairesUnder industrial constraints, microorganisms are exposed to various stresses, due to their cultivation in large scale bioreactor, altering their viability and the performances of bioprocesses. Fluctuations in physico-chemical parameters (temperature, pH, ...) are responsible for this reduction in fermentation efficiency. This Ph.D project intends to improve the robustness of an industrial ethanol producer Saccharomyces cerevisiae strain under heat stress, in order to improve its industrial production of bio-ethanol under temperature fluctuating environment. The strategy of this project is to obtain a mutant more tolerant than the wild type strain to heat stress, possessing a lower death rate. An original continuous culture reactor has been designed, coupling UV mutagenesis (generating genetic modifications) and selection pressure (temperature) to select the most robust variant. A phenomenological model was proposed to simulate microbial kinetics based on the monitoring strategy of the chemostat and to optimize the operating conditions necessary for the generation of variants. This dynamic model involves the impact of the temperature on the kinetics of growth, cell death and ethanol production in Saccharomyces cerevisiae. These kinetics were experimentally quantified as a function of the temperature and the UV treatment. Continuous cultures were carried out under the simulated conditions and some variants were characterized in very high ethanol performance fermentations in terms of growth, death and production performances. This strategy allowed us to select a variant possessing a better thermal robustness characterized by a lower death rate than the wild type strain under heat stress. However, the reduction of the death rate did not translate into better ethanol production performances
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Guergouri, Kamel. « Etude des defauts cristallins et des proprietes physiques associees dans cdte et ses alliages avec znte, mnte ». Paris 6, 1987. http://www.theses.fr/1987PA066412.
Texte intégralRésumé :
Etude de l'amelioration de cdte dans le cadre de la recherche de semiconducteurs de bonne qualite cristalline. Le premier parametre necessaire a cette amelioration et celui de la substitution de cd par zn (impurete isoelectronique et permet la reduction de la densite de dislocations d'un facteur 10. Proposition d'un modele de durcissement d'alliage pour expliquer ce phenomene. Le 2eme parametre concerne la recherche des conditions de croissance optimales
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Nicolay, N. H. « The role of DNA polymerase eta in determining cellular responses to chemo-radiation treatment ». Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:73cef89c-319d-4a14-a3a6-93e8b8dd186a.
Texte intégralRésumé :
DNA polymerase η (pol η), a crucial component of the cellular translesion synthesis pathway, allows cells to bypass and thereby temporarily tolerate DNA damage. Inherited deficiency of pol η, as reported in the variant form of xeroderma pigmentosum, predisposes to UV light-induced skin cancers. To date, pol η is the only DNA polymerase shown to exhibit a causal link to the formation of cancers in humans. However, the role of pol η in the cellular response to forms of DNA damage other than UV-induced lesions is largely unknown. In the first part of this thesis, it is shown that cells deficient in pol η are resistant to ionising radiation. Deficiency in the polymerase was associated with accumulation of cells in S phase of the cell cycle. Cells deficient in pol η demonstrated increased homologous recombination-directed repair of DNA double-strand breaks created by ionising radiation, and depletion of the homologous recombination protein X-ray repair cross-complementing protein 3 (XRCC3), abrogated the radioresistance observed in pol η-deficient cells compared to pol η-complemented cells. These findings suggest that homologous recombination mediates S phase-dependent radioresistance associated with pol η-deficiency. In the second part of this thesis, it is shown that pol η-deficient cells have increased sensitivity to the chemotherapeutic compound, oxaliplatin, compared to pol η-deficient expressing cells, but not to the drug 5-fluorouracil that is usually administered in combination with oxaliplatin in the clinical setting. Despite the importance of pol η for cellular survival following exposure to oxaliplatin, the drug did not upregulate the enzyme after either short-term or long-term exposure. Inhibition of pol η activity by siRNA-mediated knockdown of the protein sensitised cells to oxaliplatin treatment, and partially reversed acquired resistance in oxaliplatin-resistant tumour cell lines. These data suggest that pol η is an interesting target whose function can potentially be interfered with to optimise oxaliplatin-based chemotherapy. In the third part of this thesis, clinical samples obtained from oesophageal cancer patients before and after treatment with oxaliplatin-containing chemotherapy were analysed for POLH mRNA levels encoding pol η protein. Malignant tissue specimens obtained before treatment demonstrated a significantly higher level of POLH mRNA than matched normal oesophageal tissue samples. Contrary to the preclinical data, high POLH mRNA expression before therapy was shown to correlate with increased overall and disease-free survival of the patient cohort in the clinical trial. Additionally, patients with high POLH mRNA-expressing cancers had better therapeutic responses (measured by PET-CT) to oxaliplatin-based treatment than those with low levels. These data suggest that POLH mRNA expression should be tested as a biomarker to predict survival and therapeutic responses in oesophageal cancer patients treated with oxaliplatin-containing chemotherapy.
Livres sur le sujet "Etat cellulaire"
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Abellan, Stephanie, et Anais Toutin. L'oracle d'Ankaa : le guide : Libération des etats d'âme & Nettoyage de la mémoire cellulaire. Independently published, 2019.
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Abellan, Stephanie, et Anais Toutin. L'oracle d'Ankaa : le guide : Libération des etats d'âme & Nettoyage de la mémoire cellulaire. Independently published, 2019.
Trouver le texte intégralChapitres de livres sur le sujet "Etat cellulaire"
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Daniel, Juliet, Gerald Weeks et George B. Spiegelman. « Dictyostelium ras genes ». Dans Guidebook to the Sinall GTPases, 100–103. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780198599456.003.0029.
Texte intégralRésumé :
Abstract Five ras genes (rasB, rasC, rasD, rasG and rasS) and one rap gene (rap1) have been isolated and characterized in the cellular slime mold Dictyostelium discoideum (Daniel etal. 1993,1994; Reymond etal. 1984; Robbins eta/. 1989,1990). These ras subfamily genes encode 21-22 kDa GTP-binding proteins that have 52-68% amino acid identity with the human H-Ras protein (Table 1). These genes all appear to be present in a single copy since each of their cognate cDNAs hybridizes to a single, unique genomic fragment under high stringency conditions.
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Settleman, Jeffrey. « pl90 ». Dans Guidebook to the Sinall GTPases, 239–45. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780198599456.003.0075.
Texte intégralRésumé :
Abstract The p190 protein was first identified in 1990 as a phosphotyrosine-containing protein that co-immunoprecipitates with p120 Ras-GAP in growth factor-stimulated and tyrosine kinase-transformed cells (Ellis etal. 1990; Moran etal. 1991). Since that time, p190 has not been reported to associate stably with any other proteins or cellular components. p190 does, however, make contact with members of the Rho family of small GTPases, and probably binds directly to guanine nucleotides, as is described in the ‘functional studies’ section.
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Sandblom, John, Sheila Galt, Dan Roos, et Yngve Hamnerius. « Possible resonance effects of ELF magnetic fields on ion channels ». Dans Interaction Mechanisms of Low-Level Electromagnetic Fields in Living Systems, 183–98. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198577591.003.0010.
Texte intégralRésumé :
Abstract Considerable evidence has accumulated during recent years that ELF (extremely low-frequency) magnetic fields can interact with living tissues at the cellular level (Adey and Bawin 1982; Blackman etal. 1985a, b; McLeod et al. 1987; Smith et al. 1987). Existing data seem consistently to indicate the occurrence of regions of maximal absorption of energy, i.e. resonance effects, with respect to amplitude and frequencies of the magnetic fields. Examples of such systems are the calcium efflux from brain tissue (Adey and Bawin 1982; Blackman et al. 1985a, b) and the motility of diatoms (McLeod etal 1987; Smith etal. 1987) in which the responses to applied ELF signals show distinct peaks at certain frequencies.
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Tropschug, M. « Neurospora crassa cydophilins ». Dans Guidebook to Molecular Chaperones and Protein-Folding Catalysts, 382–83. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198599494.003.00148.
Texte intégralRésumé :
Abstract Fungi like Neurospora crassa or Saccharomyces cerevisiae are ideal organisms to study the cellular roles of the different peptidyl-prolyl cis-trans isomerases (PPIases) and the molecular mechanisms of action of immunosuppressants like CsA, FK506 or rapamycin (reviewed by Kunz and Hall, 1993). These drugs were originally isolated as antifungal compounds. Three families of PPIases have been described. Two of these, the cyclophilins (Cyps) and FKBPs, have been known for some time (see reviews by Schreiber, 1992; Schmid, 1993; Fischer, 1994; Galat and Metcalfe, 1995; see also the overview in this volume, p. 359). Parvulins constitute a more recently defined family (Rahfeld etal., 1994; see overview p. 365). To date only members of the Cyp (this entry) and FKBP (see entry p. 416) families have been defined in N. crassa.
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Celio, Marco R. « Calreticulin ». Dans Guidebook to the Calcium-binding Proteins, 220–21. Oxford University PressOxford, 1996. http://dx.doi.org/10.1093/oso/9780198599517.003.0028.
Texte intégralRésumé :
Abstract Calreticulin is a ubiquitous and highly conserved Ca2+-bindinglstorage protein associated with endo(sarco)plasmic reticulum membranes. Calreticulin is a multifunctional protein implicated to play a role in a variety of cellular functions ranging from Ca2+homeostasis to the control of gene expression. Rabbit calreticulin has a calculated molecular weight of 46, 567 (for recent reviews on the structure, function, amino acid sequence and localization of calreticulin see Michalak et al. 1992; Sontheimer et al. 1993; Burns et al. 1994; Nash et al. 1994 and references within). The protein migrates on 5D5 gels with an apparent molecular mass of 60 kDa (at pH 8.0) or of 55 kDa (at pH 7.0). The molecular weight of calreticulin estimated by sedimentation equilibrium is 55,000. The isoelectric point of the human protein is 4.65-4.67 and the protein stains blue with “Stains-All”. Calreticulin contains potential glycosylation sites; however, only bovine and rat liver proteins are shown to be glycosylated. In CHO cells calreticulin undergoes a heat shock-induced glycosylation (Jethmalani et al. 1994). Bovine calreticulin has one disulfide bridge (Cys120-Cys146: Matsuoka eta/. 1994).
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Kaplan, O., et J. S. Cohen. « Nuclear Magnetic Resonance Spectroscopy Studies of Cancer Cell Metabolism ». Dans Biological NMR Spectroscopy. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195094688.003.0030.
Texte intégralRésumé :
Nuclear magnetic resonance spectroscopy (NMR) is a powerful technique that provides information on biochemical status and physiological processes both in-vitro and in-vivo. The metabolism of intact cells and tissues can be studied in a continuous manner, and thus, NMR is a unique non-invasive research tool enabling detection of the metabolic changes as they occur (Cohen et al., 1983; Morris, 1988; Daly and Cohen, 1989). The first NMR study of cellular metabolism was done some 20 years ago, when Moon and Richards reported on the diphosphoglyceric acid (DPG) and pH shifts in erythrocytes (Moon, and Richards, 1973). NMR studies of metabolism of tumor cells were initiated by Navon et al. who investigated phosphorylated compounds in Ehrlich ascites cells (Navon etal., 1977). The choice of the element and isotope for a specific study of metabolism depends on its NMR properties, and the required data. The proton has the highest NMR sensitivity, and is the most abundant nucleus in biological molecules. However, this may cause difficulties in the interpretation and assignment of the 1H NMR spectrum. Moreover, since metabolic studies are usually performed in aqueous solutions, the huge signal from the water protons should be suppressed. Similarly, the wide signals arising from proteins and membrane components should be suppressed. These problems can be addressed now by several innovative NMR methods (Daniels et al., 1976; van Zijl and Cohen, 1992). The most widely used nucleus in NMR studies of metabolism has been 31p (see reviews Cohen (1988); Kaplan et al. (1992)). Phosphorous NMR spectroscopy can provide data on energy metabolism and substrate utilization, phospholipid pathways, precise intracellular pH, and membrane permeability and ion and water distribution. The spectrum is easy to interpret, but the number of compounds which are detectable is limited. Carbon NMR is also useful for NMR studies of metabolism since it is found in most biological compounds; however, 13C has a natural abundance of only 1.1%, and 13C enrichment is necessary. Other nuclei which are used less often in NMR studies of cellular metabolism are 23Na (Gupta et al., 1984), 19F (Malet-Martino, et al., 1986), and rarely 15N (Legerton et al., 1983) and 39K (Brophy et al., 1983).
Actes de conférences sur le sujet "Etat cellulaire"
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Zhou, Shuqiu, et Junxian Meng. « An Improved Algorithm of the Cellular Automata on the Evacuation Simulation ». Dans 2008 International Workshop on Geoscience and Remote Sensing (ETT and GRS). IEEE, 2008. http://dx.doi.org/10.1109/ettandgrs.2008.240.
Texte intégral
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Milligan, W. W., P. G. Sanders, C. L. White, J. P. Shingledecker et D. F. Purdy. « Design, Creep Performance and Deformation Behavior of an Eta-Phase Strengthened Nickel-Base Alloy for A-USC Power Plant Applications ». Dans AM-EPRI 2016, sous la direction de J. Parker, J. Shingledecker et J. Siefert. ASM International, 2016. http://dx.doi.org/10.31399/asm.cp.am-epri-2016p0202.
Texte intégralRésumé :
Abstract By utilizing computational thermodynamics in a Design of Experiments approach, it was possible to design and manufacture nickel-base superalloys that are strengthened by the eta phase (Ni3Ti), and that contain no gamma prime (Ni3Al,Ti). The compositions are similar to NIMONIC 263, and should be cost-effective, and have more stable microstructures. By varying the aging temperature, the precipitates took on either cellular or Widmanstätten morphologies. The Widmanstätten-based microstructure is thermally stable at high temperatures, and was found to have superior ductility, so development efforts were focused on that microstructure. High temperature tensile test and creep test results indicated that the performance of the new alloys was competitive with NIMONIC 263. SEM and TEM microscopy were utilized to determine the deformation mechanisms during creep.
Rapports d'organisations sur le sujet "Etat cellulaire"
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Meidan, Rina, et Joy Pate. Roles of Endothelin 1 and Tumor Necrosis Factor-A in Determining Responsiveness of the Bovine Corpus Luteum to Prostaglandin F2a. United States Department of Agriculture, janvier 2004. http://dx.doi.org/10.32747/2004.7695854.bard.
Texte intégralRésumé :
The corpus luteum (CL) is a transient endocrine gland that has a vital role in the regulation of the estrous cycle, fertility and the maintenance of pregnancy. In the absence of appropriate support, such as occurs during maternal recognition of pregnancy, the CL will regress. Prostaglandin F2a (PGF) was first suggested as the physiological luteolysin in ruminants several decades ago. Yet, the cellular mechanisms by which PGF causes luteal regression remain poorly defined. In recent years it became evident that the process of luteal regression requires a close cooperation between steroidogenic, endothelial and immune cells, all resident cells of this gland. Changes in the population of these cells within the CL closely consort with the functional changes occurring during various stages of CL life span. The proposal aimed to gain a better understanding of the intra-ovarian regulation of luteolysis and focuses especially on the possible reasons causing the early CL (before day 5) to be refractory to the luteolytic actions of PGF. The specific aims of this proposal were to: determine if the refractoriness of the early CL to PGF is due to its inability to synthesize or respond to endothelin–1 (ET-1), determine the cellular localization of ET, PGF and tumor necrosis factor a (TNF a) receptors in early and mid luteal phases, determine the functional relationships among ET-1 and cytokines, and characterize the effects of PGF and ET-1 on prostaglandin production by luteal cell types. We found that in contrast to the mature CL, administration of PGF2a before day 5 of the bovine cycle failed to elevate ET-1, ETA receptors or to induce luteolysis. In fact, PGF₂ₐ prevented the upregulation of the ET-1 gene by ET-1 or TNFa in cultured luteal cells from day 4 CL. In addition, we reported that ECE-1 expression was elevated during the transitionof the CL from early to mid luteal phase and was accompanied by a significant rise in ET-1 peptide. This coincides with the time point at which the CL gains its responsiveness to PGF2a, suggesting that ability to synthesize ET-1 may be a prerequisite for luteolysis. We have shown that while ET-1 mRNA was exclusively localized to endothelial cells both in young and mature CL, ECE-1 was present in the endothelial cells and steroidogenic cells alike. We also found that the gene for TNF receptor I is only moderately affected by the cytokines tested, but that the gene for TNF receptor II is upregulated by ET-1 and PGF₂ₐ. However, these cytokines both increase expression of MCP-1, although TNFa is even more effective in this regard. In addition, we found that proteins involved in the transport and metabolism of PGF (PGT, PGDH, COX-2) change as the estrous cycle progresses, and could contribute to the refractoriness of young CL. The data obtained in this work illustrate ET-1 synthesis throughout the bovine cycle and provide a better understanding of the mechanisms regulating luteal regression and unravel reasons causing the CL to be refractory to PGF2a.