Dissertationen zum Thema „Stabilité in vitro“
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Arien, Albertina. „Étude in vitro et in vivo de la stabilité de liposomes contenant de la calcitonine“. Bordeaux 2, 1995. http://www.theses.fr/1995BOR28364.
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Leenhardt, Julien. „Synthèse et études de radiomarquage au 68Ga, 99mTc, 177Lu et 161Tb de nouveaux chélatants dérivés de l'oxine en vue d'application théranostique“. Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALS009.
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Les applications théranostiques en médecine nucléaire permettraient idéalement de diagnostiquer les cancers et d’effectuer une radiothérapie interne vectorisée avec la même molécule, simplement en permutant le radionucléide utilisé. L’agent théranostique est constitué d’une partie chélatante susceptible de complexer fortement les radionucléides et d’une partie ligand qui permet d’assurer la vectorisation sur une cible tumorale. Aujourd’hui, un des couples de radionucléides le plus prometteur est constitué du Gallium-68 ou [68Ga]Ga3+ (diagnostic, émetteur de particules β+) et du Lutétium-177 ou [177Lu]Lu3+ (thérapeutique, émetteur de particules β-), mais il n’existe pas pour l’instant de système chélatant qui soit aussi bon pour les deux radionucléides. Le chélate DOTA qui est actuellement largement utilisé en médecine nucléaire possède pourtant une cinétique de radiomarquage lente, qui nécessite un chauffage du milieu réactionnel, contre-indiquant son utilisation avec des molécules vectrices thermosensibles. Au Département de Chimie Moléculaire de l’Université Grenoble Alpes, les chimistes ont l’expertise des sidérophores ou de modèles bio-inspirés, qui permettent de complexer très efficacement le gallium, ainsi que d’autres cations métalliques, qui pourraient avoir un intérêt en médecine nucléaire. Mon travail de thèse a donc été initié par des études de radiomarquage de deux de ces sidérophores abiotiques avec le [68Ga]Ga3+ et le [99mTc]Tc3+. Les données obtenues ont clairement démontré que ces sidérophores, O-TRENSOX et O-TRENOX, complexaient efficacement, à température ambiante, ces deux radioisotopes utilisés quotidiennement en imagerie nucléaire. Les études préliminaires de radiomarquage obtenues avec le Terbium-161 ou [161Tb]Tb3+ (thérapeutique, émetteur de particules β- et d’électrons Auger) ont également confirmé que ces structures pouvaient complexer des cations métalliques plus "grands" ouvrant ainsi les portes de la théranostique. Le second aspect traité au cours de cette thèse a été le développement d’un nouveau système chélatant octadentate acyclique N4O4, permettant une meilleure complexation des radionucléides plus exigeants en indice de coordination comme les lanthanides ou les actinides, en conditions douces. En utilisant plusieurs voies de synthèse différentes, nous avons réussi à synthétiser et caractériser ce nouveau ligand afin de pouvoir initier des études de radiomarquage. Ces études ont démontré une excellente complexation avec le [68Ga]Ga3+, le [177Lu]Lu3+ et le [161Tb]Tb3+ à température ambiante permettant de considérer cette nouvelle structure comme efficace pour la complexation de divers radiométaux utilisables en théranostique.L’ensemble de ces résultats indiquent que ces nouveaux systèmes chélatants possèdent des caractéristiques favorables pour le radiomarquage de nombreux radiométaux dans des conditions douces. Ces résultats ouvrent ainsi de nouvelles perspectives dans le développement de nouveaux radiopharmaceutiques pour la théranostique en médecine nucléaireTheranostic applications in nuclear medicine would ideally allow cancer diagnosis and internal vectorised radiotherapy to be carried out using the same molecule, simply by substituting the radionuclide used. The theranostic agent is made up of a chelating part capable of strongly complexing the radionuclides and a ligand part that enables delivery to a tumour target. Today, one of the most promising pair of radionuclides is Gallium-68 or [68Ga]Ga3+ (diagnostic, β+ particle emitter) and Lutetium-177 or [177Lu]Lu3+ (therapeutic, β- particle emitter), but there is currently no chelating system that is as good for both radionuclides. The DOTA chelate currently used extensively in nuclear medicine, although it has slow radiolabelling kinetics that require heating of the reaction medium, contraindicating its use with heat-sensitive molecules. At the Department of Molecular Chemistry at Grenoble Alpes University, chemists have expertise in siderophores or bio-inspired models, which enable gallium to be complexed very efficiently, as well as other metal cations that could be of interest in nuclear medicine. My thesis work therefore began with radiolabelling studies of two of these abiotic siderophores with [68Ga]Ga3+ and [99mTc]Tc3+. The data obtained clearly demonstrated that these siderophores, O-TRENSOX and O-TRENOX, complexed effectively, at room temperature, these two radioisotopes used daily in nuclear medicine imaging. Preliminary radiolabelling studies obtained with Terbium-161 or [161Tb]Tb3+ (therapeutic, emitting β- particles and Auger electrons) also confirmed that these structures could complex 'larger' metal cations, thus opening the doors to theranostics. The second aspect dealt during this thesis was the development of a new N4O4 acyclic octadentate chelating system, allowing better complexation of radionuclides with higher coordination index requirements, such as lanthanides or actinides, under mild conditions. Using several different synthetic routes, we succeeded in synthesising, purifying and characterising this new ligand in order to initiate radiolabelling studies. These studies demonstrated excellent complexation with [68Ga]Ga3+, [177Lu]Lu3+ and [161Tb]Tb3+ at room temperature, enabling us to consider this new structure as effective for complexing various radiometals that can be used as theranostics.Taken together, these results indicate that these new chelating systems have favourable characteristics for the radiolabelling of many radiometals under mild conditions. These results open up new prospects for the development of new radiopharmaceuticals for theranostics in nuclear medicine
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Courraud, Julie. „Etude du comportement des caroténoïdes et rétinoïdes en digestion in vitro : stabilité, bioaccessibilité et pouvoir antioxydant au niveau intestinal“. Thesis, Montpellier 1, 2013. http://www.theses.fr/2013MON13513/document.
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Selon la FAO, 2 milliards de personnes souffrent de la « faim cachée » qui correspond aux carences en micronutriments incluant la carence en vitamine A, principale cause de cécité dans le monde. Par ailleurs, une alimentation excédentaire est source de stress oxydant pour le corps, facteur de risque de nombreuses maladies non transmissibles comme le diabète et les maladies cardiovasculaires. Contenus dans les produits végétaux, certains caroténoïdes représentent une source indirecte de vitamine A et pourraient participer aux effets bénéfiques de la consommation de fruits et légumes via des propriétés antioxydantes. Dans cette thèse, le comportement in vitro des caroténoïdes et rétinoïdes pendant la digestion a été étudié, depuis leur libération de la matrice alimentaire jusqu'à leurs interactions avec les cellules intestinales. Mes recherches s'articulent autour de la micellisation : processus clé de l'absorption des caroténoïdes et rétinoïdes. Dans un premier temps, la stabilité et la bioaccessibilité en digestion in vitro de ces composés purs ont été comparées à celles de leurs homologues issus d'un jus de carotte, d'épinards crus et cuits et d'une farine fortifiée. Dans un deuxième temps, un nouveau modèle d'oxydation de nano-émulsions intestinales à base de sels biliaires (SB) a été développé. Les relations entre structure des micelles mixtes, réactivité à l'oxydation et protection par des antioxydants ont été étudiées grâce notamment au suivi de la dégradation des acides gras. Enfin, des expériences préliminaires ont été menées sur la réactivité enzymatique de cellules coliques (Caco-2) à divers oxydants et aux micelles mixtes. Pendant la digestion in vitro, le β-carotène et palmitate de rétinyl purs étaient particulièrement instables contrairement à la lutéine et à l'acétate de rétinyl. De plus, la matrice alimentaire protège ces composés et favorise leur bioaccessibilité surtout lorsqu'elle est broyée ou cuite. En effet, les prétraitements ont un impact conséquent sur la libération des caroténoïdes et doivent être considérés comme des moyens sérieux pour optimiser les apports. Les nano-émulsions intestinales mises au point se composaient de micelles mixtes sphériques ou cylindriques, ces dernières étant les moins résistantes à l'oxydation. En effet, la distribution des molécules de SB doit être différente selon la morphologie de la micelle, impactant ainsi leur réactivité. Dans nos conditions expérimentales, l'AAPH fut le seul oxydant efficace. L'α-tocophérol et la lutéine ont significativement ralenti la dégradation des acides gras contrairement au β-carotène. Leur place au sein de la micelle (cœur ou bordure) pourrait expliquer ces observations. Enfin, aucun des oxydants testés n'a significativement modifié l'activité catalase des cellules Caco-2. En revanche, la mise en contact avec les micelles à base de SB ont significativement diminué l'activité des 3 enzymes suivies. L'effet était positivement corrélé à la concentration en SB dont la conjugaison fut un élément déterminant. Finalement, le β-carotène, la lutéine, et l'acétate de rétinyl présents dans ces micelles ont en partie rétabli l'activité de la catalase contrairement au rétinol, palmitate de rétinyl et à l'α-tocophérolAccording to the FAO, two billions of people suffer from the « hidden hunger » which corresponds to micronutrient deficiencies and includes the vitamin A deficiency, principal cause of blindness throughout the world. Besides, an excessive food consumption entails an oxidative stress for the organism which increases the risk to develop non communicable diseases such as diabetes and cardiovascular diseases. Present in numerous fruits and vegetables, some carotenoids are an indirect source of vitamin A and could also contribute to the health benefits of the consumption of fruits and vegetables via antioxidant properties. In this thesis, in vitro behaviour of carotenoids and retinoids during in vitro digestion (IVD) has been studied, from their release from dietary matrices to their interactions with intestinal cells. My research is structured around micellisation: key process of carotenoid and retinoid absorption. First, stability and bioaccessibility during IVD of these pure compounds have been compared with those of their homologues from carrot juice, raw and cooked spinach and fortified flour. Second, a new model of oxidation of intestinal bile salt (BS)-based nanoemulsions has been developed. Relations between mixed micelles structure, reactivity to oxidation and protection by antioxidants have been studied using fatty acid degradation monitoring. Finally, preliminary experiment were carried out on enzymatic reactivity of colon cells (Caco-2) to various oxidants and mixed micelles. During IVD, pure β-carotene and retinyl palmitate were particularly unstable conversely with lutein and retinyl acetate. Moreover, the dietary matrix protected these compounds and favoured their bioaccessibility especially when it was grounded or cooked. Indeed, pre-treatment have a significant impact on carotenoid release and should be considered as serious means to optimize intake. Developed intestinal nanoemulsions constituted of spherical or cylindrical micelles, the latter being less resistant to oxidation. Distribution of BS molecules is likely to differ according to the micelle morphology, thereby influencing their reactivity. In our experimental conditions, AAPH only was efficient as oxidant. Lutein and α-tocopherol significantly slowed fatty acid degradation, conversely with β-carotene. Their location within the micelle (core or border) could explain these observations. Besides, none of the tested oxidant significantly modified the catalase activity of Caco-2 cells. However, the contact with BS-based nanoemulsions significantly decreased the activity of the three tested enzymes. This effect was positively correlated with BS concentration whose conjugation revealed determining. Finally, β-carotene, lutein and retinyl acetate in micelles partly re-established catalase activity, conversely with retinol, retinyl palmitate and α-tocopherol. To conclude, IVD is an easy tool which allows independent comparisons of several parameters on micronutrient behaviour during digestion. Furthermore, the confrontation of different matrices may help to develop relevant strategies against vitamin A deficiency. Proposed nanoemulsions displayed various physical and chemical characteristics, thereby influencing their reactivity to oxidation. The antioxidant capacity of lutein and α-tocopherol could be observed in this new model. Lastly, the preliminary results on Caco-2 cells revealed some interesting interactions between micellised BS and antioxidant enzymes. Numerous questions arose that could not be addressed in this work but open perspectives for the future
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Debin, Arnaud. „Formation et stabilité des triples hélices purines : études in vitro et dans les cellules de mammifères“. Paris 11, 2000. http://www.theses.fr/2000PA11T013.
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Les oligonucléotides qui forment des triples hélices (OFT) sont de courts fragments d'acides nucléiques capables de reconnaître sélectivement des séquences d 'ADN double brins. Dans ce travail, nous avons étudié la formation et la stabilité de triples hélices obtenues à l'aide d'oligonucléotides composés de purines, les OFT (G,A). Nous avons sélectionné in vitro les séquences d'ADN double brin capable de former des triples hélices stables à 20°C et 50°C dans des conditions ioniques déterminées. Cette sélection a été obtenue par une double approche aptamère dans laquelle les séquences de départ des oligonucléotides et les duplex cibles d 'ADN sont aléatoires. Les séquences sélectionnées obéissent à 2 règles : - elles possèdent toutes un grand pourcentage de guanine: elles sont dites riches en G - pour un nombre de G donné, la stabilité du triplex résultant est plus grande si les guanines se suivent en bloc non interrompu par des adénines. Cette étude démontre l 'importance cruciale de la composition relative en guanine de l'OFT sur la stabilité de la triple hélice. Elle conduit à la notion de triples hélices riches en G, qui englobe les triples hélices purines G,A mais aussi les triples hélices mixtes G,T. L'étude de la formation et de la stabilité des triples hélices riches en guanine in vitro, dans des conditions ioniques mimant les conditions ioniques intracellulaires, a confirmé la grande sensibilité des triples hélices purines aux concentrations en magnésium mais aussi au potassium, notamment sur la cinétique de formation, limitant potentiellement leur utilisation en culture cellulaire. Afin de surmonter l'effet inhibiteur du potassium, un nouveau concept d'oligonucléotide OFT, que nous appelons le concept " oligonucléotide ZIPPER", a été développé. Nous avons ensuite étudié la stabilité et la formation des triples hélices purines ex vivo, grâce à l'utilisation d'une technique d 'empreinte au Diméthylsulfate (DMS), permettant la visualisation de l'empreinte de 1'oligonucléotide sur l'ADN directement dans les cellules. Ceci a permis de démontrer la stabilité des triples hélices dans les cellules de mammifères lorsqu'elles sont introduites artificiellement dans les cellules après préformation in vitro. En revanche, nous n’avons pu détecter par cette méthode la formation des triples hélices directement dans les cellulesTriplex-Forming Oligonucleotides (TFOs) are short nucleic acid fragments able to recognize selectively double-stranded DNA sequences. In this thesis, we have studied the formation and stability of triples helices using purine TFOs (composed of Guanines and Adenines). Firstly, we have selected double-stranded DNA sequences capable offorming stable triplexes at 20 or 5. Q. °C with corresponding 13mer purine oligonucleotides. This selection was obtained by a double aptamer approach where both the starting sequences of the oligonucleotides and the target DNA duplex were random. The results of selection were confirmed by a cold exchange method and the influence ofthe position of a 'mismatch' on the stability ofthe triplex was documented in several cases. The selected sequences obey two rules: (i) they have a high G content; (ii) for a given G content the stability of the resulting triplex is higher if the G residues lie in stretches. Secondly, triplex formation was studied in conditions mimicking potassium concentrations and temperatures in cells. In presence of 1OmM Mgcl2, KCl concentrations up to 150 mM significantly lowered both efficiency (triplex: initial duplex) and rate constants of triplex formation. For 20 mer TFO, no dissociation of triplex was observed during 24 hours either in the absence of monovalent cations or in the presence of 150 mM KCl. In this case, the negative effect of the KCl is probably due to the self-association of the oligonucleotide in competitive structures. This negative effect may be overcome by the prior formation of a short duplex either on the 3 '-or 5'- end of the 20mer TFO. We refer to these partial duplexes as 'zipper' TFOs. It was demonstrated that a 'zipper' TFO could forma triplex over the full lengh of the target, thus unzipping the short complementary strand. Thirdly, triplex stability and formation was studied in live mammalian cells. Ex vivo DMS footprint analysis after electroporation of the pre-formed into the cell have shown the presence of the triple helix inside the cells. However we were unable to show triplex formation inside cells using various methods of oligonucleotide delivery, and using various target sequences. Our results show that neither (i) chromatinization of the DNA target, (ii) intracellular K+ concentration nor (iii) cytoplasmic versus nuclear separation of the TFO and DNA target are responsible for the intracellular arrest of triplex formation. We suggest the existence of a cellular mechanism, based on a compartmentalization of TFOs and/or TFO trapping, which separates oligonucleotides from the DNA target. Further work is needed to find oligonucleotide derivatives and means for their delivery to overcome the problem of triplex formation inside cells
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Pinguet, Frédéric. „Optimisation du schéma d'administration du MELPHALAN : Etudes in vitro sur des lignées cellulaires cancéreuses d'origine humaine et étude in vivo chez l'homme : [thèse soutenue sur un ensemble de travaux]“. Montpellier 1, 1998. http://www.theses.fr/1998MON13515.
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Rouinsard, Alexandre. „Étude du caractère de panachure et de sa stabilité lors de la micropropagation de plantes monocotylédones“. Thesis, Rennes, Agrocampus Ouest, 2021. http://www.theses.fr/2021NSARC156.
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La micropropagation des variétés à feuillage panaché (plusieurs couleurs sur une même feuille) peut générer des plantes non conformes au phénotype d’origine, particulièrement dans le cadre de plantes monocotylédones acaules. Or, par leur caractère fortement ornemental, ces variétés présentent un fort potentiel commercial. L’objectif était de déterminer les potentialités de micropropagation des monocotylédones panachées dans un contexte industriel et commercial, de définir la stabilité de leurs phénotypes, et de comprendre l’apparition des plantes hors-type. Les observations de coupes foliaires au microscope confocal à balayage laser sur les quatre cultivars étudiés Yucca gloriosa ‘Variegata’ (YgVAR), Yucca flaccida ‘Golden Sword’ (YflGS), Phormium tenax ‘Jessie’ (PtJE) et Cordyline australis ‘Pink Passion’ (CaPP) ont révélé que tous les cultivars étaient des chimères périclines, soit une panachure liée à un méristème stratifié avec plusieurs génotypes différents. En micropropagation,YgVAR a présenté des taux de conformité élevés, PtJE des taux modérés et CaPP de faibles taux. Des analyses histologiques sur les vitroplants ont mis en évidence des différences majeures dans le développement et le comportement de multiplication in vitro de ces trois espèces de l’ordre des Asparagales : YgVAR n'a développé que des méristèmes axillaires (AxM), PtJE principalement des AxM et quelques méristèmes adventifs (AdM), et CaPP à la fois des AxM et des AdM. Alors que les méristèmes axillaires préformés maintiennent la structure chimérique, les méristèmes adventifs la maintiennent peu. Donc la stabilité de la panachure de ces variétés dépend de leur propension à se propager par méristèmes adventifs. Des essais pour abaisser la dominance apicale et stimuler les méristèmes axillaires ont été menés, ainsi qu’une analyse du transcriptome des différents tissus panachés chez YflGS. Des protocoles de production industrielle adaptés à chaque cultivar sont finalement proposésThe micropropagation of variegated cultivars (several colors on the same leaf) can generate off-type plants to the original phenotype, particularly in the case of monocotyledonous plants. However, because of their highly ornamental character, these cultivars have a strong commercial potential. The objective were to determine the micropropagation potential of variegated monocots in an industrial and commercial context, to define the stability of their phenotypes, and to understand the origin of off-types. Observations of leaf sections under a confocal laser scanning microscope on the four studied cultivars: Yucca gloriosa 'Variegata' (YgVAR), Yucca flaccida 'Golden Sword' (YflGS), Phormium tenax 'Jessie' (PtJE), and Cordyline australis 'Pink Passion' (CaPP) revealed that all cultivars were periclinal chimeras, i.e., a variegation bound to stratified meristem with several different genotypes.In micropropagation, YgVAR showed high compliance rates, PtJE moderate rates and CaPP low rates. Histological analyses on vitroplants revealed major differences in the development and in vitro propagation behavior of these three species of the order Asparagales: YgVAR developed only axillary meristems (AxM), PtJE mainly AxM and some adventitious meristems (AdM), and CaPP both AxM and AdM. While preformed axillary meristems maintain the chimeric structure, adventitious meristems maintain little. Thus, the variegation stability of these chimeras depends on their propensity to propagate by adventitious meristems. Trials to lower apical dominance and stimulate axillary meristems were conducted, as well as transcriptome analysis of different variegated tissues in YflGS. Industrial production protocols adapted to each cultivar are finally proposed
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Vernier, Arnaud. „Développement instrumental en spectrométrie de masse pour le diagnostic in vitro en microbiologie clinique“. Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-00986856.
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La spectrométrie de masse, en particulier le couplage HPLC/MRM3, est un outil bien adapté au diagnostic in vitro, particulièrement en microbiologie clinique. L'utilisation en routine de cette technologie est cependant tributaire de sa sensibilité et de sa spécificité. Ce travail de thèse a pour objectif d'étudier la possibilité d'éjecter et de détecter simultanément et de façon sélective des ions de ratio masse/charge donnés, ceux-ci étant confinés dans un piège ionique quadrupolaire. Cette approche permet de supprimer les étapes de balayage en masse et d'intégration mathématique du signal en mode MRM3 ce qui permet de gagner à la fois en sensibilité et en spécificité (en diminuant le temps de cycle et en diminuant le rapport signal sur bruit). Cet objectif a été poursuivi premièrement par une étude théorique approfondie des équations du mouvement des ions dans un piège radiofréquence ; deuxièmement par une étude numérique de la stabilité de ces équations et enfin troisièmement par une validation expérimentale de ces résultats théoriques. La présentation de ces trois approches fait l'objet du présent mémoire
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Helary, Christophe. „Hydrogels de collagène concentrés pour des substituts dermiques améliorés : évaluation in vitro et in vivo“. Paris 6, 2010. http://www.theses.fr/2010PA066288.
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Ibrahim, Hany. „Développement de méthodes analytiques : détermination de médicaments dans les fluides biologiques et études de stabilité de nouveaux composés antiplasmodiaux in vitro“. Toulouse 3, 2008. http://www.theses.fr/2008TOU30283.
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L'analyse de composés ou de métabolites dans les fluides biologiques nécessite des méthodes sélectives et très sensibles pour leur détection et leur quantification lors des études pharmacologiques et cliniques. La première partie du travail a pour objet l'analyse d'antiinflammatoires non stéroïdiens dans des médicaments et du sérum, par HPLC et détection de fluorescence. En complément, une comparaison entre l'HPLC avec fluorescence conventionnelle et la µHPLC avec fluorescence induite par laser a été menée pour déterminer la chloroquine et la quinine dans le sérum humain en utilisant de très faibles volumes d'échantillons injectés. Ceci a conduit à la méthode la plus sensible connue à ce jour (LOD < 2 femtomoles). Dans une seconde partie, la biotransformation de nouvelles entités chimiques (NCE) à activité antiplasmodiale a été étudiée en utilisant plusieurs systèmes analytiques incluant les méthodes LC-MS. La stabilité des NCE in vitro et leurs interactions avec les globules rouges ont été recherchées afin d'approcher leurs mécanismes d'action. L'utilisation de molécules marquées a permis de confirmer l'interprétation des spectres de masse et de comprendre les premières étapes de la biotransformationThe analysis of compounds and/or metabolites in biological fluids needs very sensitive and selective methods for the detection and quantification in pharmacological and clinical studies. The first part of the work concerns the determination of NSAIDs in pharmaceuticals and human serum by dual-mode gradient HPLC and fluorescence detection. In addition a comparison between HPLC with conventional fluorescence, and µHPLC with laser induced fluorescence detection was carried out to determine chloroquine and quinine in human serum, using very small injected samples. This resulted in the most sensitive method known to date (LOD < 2 femtomoles). In the second part of the work, the biotransformation of new chemical entities (NCEs) showing promising antiplasmodial activity has been studied with several analytical systems including LC-MS methods. The stability of the NCEs in vitro and their interactions with human red blood cells have been investigated to begin to understand their mechanisms of action. Tagged molecules have been used to confirm the interpretation of the mass spectra and the first step in the biotransformation pathway
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Gonnet, Maud. „Evaluation in vitro et in vivo de la stabilité et de la biodisponibilité de molécules liposolubles encapsulées et incluses dans une matrice modèle“. Phd thesis, Université d'Angers, 2010. http://tel.archives-ouvertes.fr/tel-00538930.
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Ce travail de thèse porte sur l'encapsulation du β-carotène (βC) dans des nanocapsules lipidiques (NCLs) formulées avec des constituants de grade alimentaire, afin d'augmenter sa biodisponibilité. Dans un premier temps, nous avons mis en évidence, in vitro, que les NCLs étaient dégradées par l'association de sels biliaires et d'enzymes pancréatiques. La déstabilisation des NCLs pourrait rendre le βC accessible à l'absorption grâce à son inclusion dans des structures de type micellaire. Dans un deuxième temps, la modélisation des propriétés rhéologiques et électriques de l'interface des NCLs a été réalisée par tensiométrie et zétamétrie. Ces études ont montré que l'encapsulation du βC n'avait pas d'impact sur les propriétés rhéologiques et électrophorétiques de l'interface. Une étude sur matrice modèle (émulsion alimentaire complexe) a montré que l'inclusion du βC dans les NCLs protégeait le βC et augmentait ses propriétés antioxydantes. Enfin, des études in vivo chez le rat ont souligné que l'encapsulation d'un composé radiomarqué lipophile augmentait son absorption intestinale. Ce système devrait par conséquent augmenter la biodisponibilité du βC grâce à sa solubilisation dans le coeur lipidique et la dispersion fine de la phase huileuse dans un milieu digestif.
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Gellis, Christophe. „Optimisation de la corticothérapie pédiatrique par voie nutritionnelle parentérale : étude de stabilité de l'hémisuccinate de méthylprednisolone in vitro et études pharmacocinétiques in vivo“. Clermont-Ferrand 1, 2006. http://www.theses.fr/2006CLF1PP03.
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La stabilité et la compatibilité de l'hémisuccinate de méthylprednisolone, à des concentrations 25 à 125 µg/ml en mélanges nutritifs parentéraux de formulations pédiatriques binaire et ternaire ont été établies pour une durée de 7 jours à + 4°C suivis de 24 heures à température ambiante. L'étude des paramètres pharmacocinétiques de l'hémisuccinate de méthylprednisolone et de la méthylprednisolone, après administration en bolus intraveineux de SOLUMEDROL® dans 2 ml de différents véhicules (milieux nutritifs ou chlorure de sodium à 0,9%), chez le lapin de race néo-zélandaise, a montré une influence des mélanges contenant une émulsion lipidique. En présence de lipides les clairances des deux molécules et le volume de distribution de l'ester de méthylprednisolone sont significativement réduits. Lors de l'administration en perfusion de SOLUMEDROL® dans les mêmes milieux nutritifs en perfusion continue de 24 heures chez l'animal, aucune différence significative des paramètres pharmacocinétiques de la méthylprednisolone n'est mise en évidence. Ces données nous permettent de poser les bases pharmacocinétiques d'une administration du SOLUMEDROL® chez l'enfant, en perfusion dans un milieu nutritif parentéralStability and compatibility of hemisuccinate methylprednisolone with concentrations 25 to 125 µg/ml in two in one and all in one paediatric parenteral nutritive mixtures were established for a 7 days duration at the temperature of 4°C followed by 24 hours in ambient temperature. The study of pharmacokinetic parameters of hemisuccinate methylprednisolone and methylprednisolone, after administration in intravenous bolus of SOLUMEDROL® in 2 ml of various vehicles (nutritive mixtures or sodium chloride 0,9%) in New-Zealand rabbit, showed an influence of the mixtures containing a lipid emulsion. In presence of lipids the clearances of the two molecules and the volume distribution of ester of methylprednisolone are significantly reduced. During administration of SOLUMEDROL® by continuous perusion in the same nutritive mixtures for 24 hours in the animal, no signifiant difference of the pharmacokinetic parameters of methylprednisolone is highlighted. These data established the pharmacokinetic bases of an administration of SOLUMEDROL® to the child by continuous nutritive perfusion
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Millerioux, Jennifer. „Formulation et évaluation de la stabilité et de l'efficacité de topiques protecteurs vis-à-vis des composés organophosphorés“. Lyon 1, 2009. http://n2t.net/ark:/47881/m6v40sbv.
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Les neurotoxiques organophosphorés (NOP) sont extrêmement toxiques et peu volatils. Dans des conditions normales de température et de pression, ils peuvent pénétrer rapidement la peau sous forme liquide et exercer leurs effets délétères. En milieu civil ou militaire, leur utilisation potentielle est toujours redoutée. Le développement de dispositifs de protection cutanée vis-à-vis de ces agents est donc d’un intérêt majeur pour les armées et la sécurité civile. Dans ce contexte, les objectifs de ce travail ont été de formuler et évaluer la stabilité et l’efficacité de topiques protecteurs cutanés (TP) vis-à-vis des NOP. Le premier objectif a consisté à mettre au point des TP de compositions et de formes galéniques différentes (émulsions, gels) puis à valider leurs stabilités physicochimiques. Cent trente TP ont été formulés et 30 ont montré une stabilité physicochimique satisfaisante. Le second objectif a été d’évaluer l’efficacité des TP les plus prometteurs vis-à-vis des composés organophosphorés. Actuellement il n’existe pas de standardisation de ce type d’étude. Par conséquent, l’utilisation de plusieurs tests in vitro et in vivo (membranes biologiques ou synthétiques, NOP ou simili), dont la pertinence et la fiabilité ont été déterminées, nous a permis d’établir une logique de criblage pour l’évaluation de l’efficacité des TP. Parmi les 13 formulations testées, les résultats ont montré qu’un gel hydro-alcoolique apporte une protection cutanée significative et supérieure aux produits de référence testés vis-à-vis du VX, un NOP d’intérêtPrevention of exposure to the neurotoxic organophosphorus compounds (OP) that are quickly absorbed in the skin is a major concern both for pesticide users and soldiers. Skin barrier creams are being developed to complement or replace uncomfortable chemical protective suits. The objectives of this work were to formulate and assess physicochemical stability and protective efficacy of topical skin protectant (TSP) against OP compounds. The first objective was to formulate several different TSP (emulsions, gel) and validate their physicochemical stability. The second objective was to determine the consistency of results from in vitro tests and the importance of the formulation composition in the skin protective efficacy. Quick evaluation of formulations efficacy mainly relies on in vitro tests which lead to consistent, complementary and relevant results. Our results indicated that the least effective formulations could be quickly identified by performing in vitro permeation tests with silicone membrane and by evaluating interfacial interactions between formulations and OP. We showed that a hydrogel containing specific hydrophilic polymers was by far the most effective of the formulations evaluated against VX, OP compounds, skin permeation in vitro
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Namy, Patrick. „Régulation mécanique de l'angiogenèse in vitro : analyse par un modèle aux dérivées partielles des interactions cellules-substrat“. Phd thesis, Université Joseph Fourier (Grenoble), 2004. http://tel.archives-ouvertes.fr/tel-00007601.
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Le développement de capillaires sanguins à partir d'un réseau pré-existant, l'angiogenèse, joue un rôle fondamental dans de nombreux contextes physiopathologiques, tels la cicatrisation des tissus ou le développement d'une tumeur solide. Dans cette thèse, nous nous sommes intéressés à la régulation de ce phénomène par les facteurs mécaniques (rigidité, viscosité, traction cellulaire). Dans un dialogue permanent entre l'expérimentation et la modélisation, nous avons développé un modèle théorique biomécanique minimal des premières étapes de l'angiogenèse in vitro, où l'angiogenèse est supposée issue d'une instabilité mécanique entre les forces actives de traction cellulaire et la résistance passive viscoélastique de la matrice extracellulaire. Notre modèle consiste en un système d'équations aux dérivées partielles non-linéaires couplées, résolu par la méthode des éléments finis. Nous avons mené des analyses de stabilité linéaire et non-linéaire de l'état d'équilibre homogène pour déterminer les points de bifurcation du système correspondant à une instabilité de Turing. Nous avons ensuite effectué une étude approfondie de l'influence des différents paramètres sur la formation du réseau. Les résultats des simulations numériques sont comparés avec succès aux résultats expérimentaux, obtenus par notre équipe ou extraits de la littérature. Dans une seconde partie de nos travaux, nous avons étudié des voies de régulation possibles, par les effets mécaniques, de la dégradation de la matrice extracellulaire. Nous avons alors montré que la régulation mécanique de la dégradation pouvait être un processus clé de l'angiogenèse in vitro.
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Booij, Isabelle. „Recherche de marqueurs biochimiques en vue de la caractérisation variétale chez le palmier dattier (Phoenix dactylifera L. ), et étude de la stabilité de ces marqueurs pendant et après culture "in vitro"“. Montpellier 2, 1992. http://www.theses.fr/1992MON20099.
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Une analyse de la composition chimique des fruits et du polymorphisme enzymatique de folioles de palmes a ete entreprise pour etudier la variabilite genetique chez le palmier dattier (phoenix dactylifera l. ) et evaluer celle induite par les methodes de culture in vitro. Les teneurs en eau, sels mineraux, sucres et acides amines libres des dattes ne permettent pas de distinguer les differents cultivars entre eux, mais peuvent se reveler interessants lors de l'etude de la physiologie des fruits, notamment au cours de leur maturation. La comparaison de la composition chimique de dattes recoltees sur des rejets et des vitroplants acclimates de memes cultivars n'a revele aucune difference notable pour les cultivars obtenus par bourgeonnement axillaire (bou sthammi noire, mejhool, thoory et zahidi). Cependant, les dattes mures du cultivar deglet nour, obtenues par embryogenese somatique, montrent des differences importantes de leur teneur en saccharose, acide aminobutyrique, acide glutamique, arginine et asparagine. L'etude de 15 systemes enzymatiques par electrophorese sur phast system a revele un polymorphisme intravarietal important. L'etude de 5 systemes enzymatiques permet de distinguer 69% des cultivars analyses. Les cultivars nabout seif, thoory et halawy presentent un genotype unique pour le systeme esterase. Cet outil n'a pas permis de mettre en evidence une variabilite isoenzymatique chez les vitroplants. L'analyse des plantules en cours de multiplication in vitro a permis de mettre en evidence une succession de phases de bourgeonnement et de phases de croissance. On a mis en evidence une correlation positive entre le bourgeonnement et l'activite des peroxydases
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Reinberg, Emilie. „Étude in vitro de la stabilité gastro-intestinale et de l'activité biologique de la microcine J25 : impact sur l'équilibre du microbiote colique et activité inhibitrice contre Salmonella enteritidis“. Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26502.
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La microcine J25 (MccJ25), une bactériocine en forme de lasso synthétisée par Escherichia coli et ayant une activité inhibitrice contre Salmonella, a été produite et purifiée d’un surnageant d’E. coli pTUC202. La stabilité et l’activité biologique de cette bactériocine au niveau gastro-intestinal, ainsi que son impact sur l’équilibre du microbiote colique, ont été étudiés à l’aide d’un système de fermentation en continu avec cellules immobilisées reproduisant les conditions physiologiques et microbiologiques du côlon. L’analyse par qPCR du microbiote colique n’a révélé aucun effet significatif sur l’équilibre du microbiote de la MccJ25 lorsqu’elle est ajoutée à 0,4, 2 et 5 μM. Des tests d’activité antibactérienne ont démontré que la MccJ25 reste active contre Salmonella enteritidis dans les conditions coliques testées. Ces résultats suggèrent un fort potentiel d’utilisation de la MccJ25 comme alternative aux antibiotiques aussi bien chez l’animal que chez l’humain.Microcin J25 (MccJ25) is a lasso-shaped bacteriocin with an antibacterial activity against Salmonella. This bacteriocin was produced and purified from the supernatant of Escherichia coli pTUC202. Its stability and biological activity in the gastrointestinal tract as well as its impact on the colonic microbiota equilibrium were studied using a continuous fermentation system with immobilized fecal microbiota simulating the physiological and microbiological conditions of the colon. Analysis of colonic microbiota by qPCR revealed no significant effect of MccJ25 on microbiota equilibrium at concentrations of 0.4, 2 et 5 μM. Antibacterial activity assays demonstrated that MccJ25 remains active against Salmonella enteritidis in the tested colonic conditions. These results are highly promising for the use of MccJ25 as an alternative to antibiotics in animals as well as in humans.
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De, vaugelade du breuillac Segolene. „Évaluation des paramètres nécessaires à la détermination de la Date de Durabilité Minimale (DDM) et de la Période après Ouverture (PAO) des émulsions cosmétiques“. Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX022.
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Depuis le 11 juillet 2013, date d’application du Règlement cosmétique (CE) No 1223/2009, les metteurs sur le marché sont dans l’obligation de mentionner sur leurs produits la Date de Durabilité Minimale (DDM), ou si celle-ci excède 30 mois, la Période Après Ouverture (PAO). L’estimation de ces dates n’est pas encadrée réglementairement. Cosmetics Europe, l’Agence nationale de sécurité du médicament et des produits de santé, le Comité scientifique pour la sécurité du consommateur ou encore la Commission Européenne proposent des lignes directrices, mais les conditions d’étude pour la détermination de la DDM et de la PAO restent encore à l’appréciation de la personne responsable de la commercialisation du produit. L’objectif de ce travail était d’étudier les conditions nécessaires à la mise en place d’un protocole de mesure de la stabilité d’émulsions cosmétiques, permettant de déterminer la DDM du produit de manière fiable et rapide. Pour cela, une approche expérimentale sur une émulsion représentative de l’industrie cosmétique a été menée. L’évolution des paramètres organoleptiques, physico-chimiques et microbiologiques a été évaluée, en accéléré (température augmentée) et en temps réel. Une approche statistique a montré que les propriétés sensorielles évoluent différemment en fonction de la température et du matériau dans lequel l’émulsion est stockée. L’établissement d’un modèle de correspondance entre le vieillissement en conditions réelles et en conditions accélérées a pu être proposé pour certains paramètres physico-chimiques. Les études de microbiologie se sont tout d’abord concentrées sur la validation d’une méthode commerciale, alternative au dénombrement des germes aérobies totaux encadré par la norme ISO 21149, pour une application dans le domaine cosmétique. Après validation, la méthode a été utilisée comme un outil simple, rapide et économique pour le suivi de la stabilité microbiologique de l’émulsion de référence. La dégradation des conservateurs et de l’antioxydant présents dans la formule de référence a été suivie par chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC-MS). Ce suivi a permis de mettre en évidence l’effet probable de la lumière sur la dégradation des actifs de l’émulsion. A ces tests ont été associés une stratégie analytique visant à étudier la photostabilité de l’émulsion. Les études ont porté sur deux molécules : l’acide déhydroacétique et l’alpha-tocophérol. La stratégie a permis de caractériser les mécanismes impliqués dans les réactions de photodégradation. La chromatographie en phase gazeuse couplée à la spectrométrie de masse multi-étapes (GC-MSn) et la chromatographie en phase liquide couplée à la spectrométrie de masse haute résolution en tandem (LC-HR-MS/MS) ont été utilisées pour la séparation et l'identification structurale des photoproduits. La détection des photoproduits majoritaires dans l’émulsion de référence, après irradiation UV-visible, montre la possible formation des photoproduits dans une matrice complexe de type émulsion huile/eau. Les résultats des tests de toxicité, in silico et/ou in vitro, ont démontré l’importance de prendre en compte la formation éventuelle de photoproduits dans l’évaluation de la sécurité d’un produit cosmétiqueAccording to Cosmetic Regulation 1223/2009, implemented in July 2013, the manufacturer must mention the Date of Minimum Durability (DMD), or if DMD exceeds 30 months, the Period After Opening (PAO) on the product packaging. At the present time, no text regulates the procedures applicable to the validation of a DMD or a PAO. Some guidelines are published by Cosmetics Europe, the National Agency for the safety of medicines and health products, the Scientific Committee for consumer safety, or the European Commission; but the evaluation remains at the discretion of the person responsible for marketing the product. In this context, this work proposes recommendations to establish a stability protocol in order to quickly determine the DMD. Experimental approaches on an emulsion representative of the major category in the cosmetics industry have been established. Organoleptic, physicochemical and microbiological stabilities were evaluated. The emulsion stability has been tested in accelerated conditions and in real time. A statistical approach has been proposed to evaluate the product shelf life according to its organoleptic properties. The sensory properties of the cosmetic emulsion changed differently depending on the temperature and the material in which it has been stored. A mathematical correlation between the results of studies under normal and those obtained under accelerated conditions has been proposed for some parameters. A microbiological study focused on the validation of a commercially available method, alternative to total count of aerobic microorganisms, normed by the ISO 21149 for cosmetic application. Once validated, this method has been used as an economical, quick and easy tool to evaluate the microbiological stability of cosmetic emulsions. Gas chromatography coupled with mass spectrometry was used to follow the degradation of antioxidant and preservatives. To take into account the photostability of the emulsion, an analytical strategy was proposed to identify the mechanisms involved in phototransformation reactions. The study focused on two molecules: dehydroacetic acid and alpha-tocopherol. Both gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) and liquid chromatography coupled with ultrahigh resolution mass spectrometry (LC-UHR-MS) were used for the separation and the structural identification of photoproducts. The main photoproducts were detected in the reference emulsion after UV-visible irradiation, thus showing the possible formation of photoproducts in a complex oil/water emulsion. Both in silico and in vitro toxicity tests highlighted the need for taking into account the potential formation of photoproducts in the safety evaluation of a cosmetic product
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Meric, Elise. „Compréhension des effets matrices de boissons à base de jus de fruits enrichies en ingrédients protéiques sur la stabilité de ces jus et évaluation in vivo et in vitro de l'impact de cet enrichissement protéique sur le système glycémique“. Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29032/29032.pdf.
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Pham, Andrew C. „In vitro stability of cannabinergic prodrugs in plasma“. Thesis, Boston University, 2012. https://hdl.handle.net/2144/12589.
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Thesis (M.A.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.The endocannabinoid system has been a promising target for novel drug therapies, especially because of its role in alleviating neuropathic pain. Recent drug development has been geared to specifically target CB2 receptors to inhibit neuropathic pain without the psychotropic side effects associated with CB1 agonism. There have been problems developing oral formulations of CB2-specific cannabinergic drugs because of their low bioavailability. This issue can be addressed by creating prodrugs of these compounds with enhanced bioavailability. This study evaluates the in vitro half lives of monofunctional and bifunctional esteratic prodrug structures of two CB2-targeted cannabinergic drugs. These prodrug formulations have one or two ester bonds that must be hydrolyzed before the active drug is released. The prodrugs and active products were incubated in human, mouse, and rat plasma, as well as non-enzyme containing buffers, and concentrations were measured over time by HPLC. The active drug products were stable in all solutions. The prodrugs were found to have in vitro half lives in human plasma ranging from 2.50 to 6950 minutes and exhibited accelerated degradation in mouse and rat plasma for the majority of compounds. Non-enzymatic hydrolysis was observed in TME buffer for many of these compounds, but at a much slower rate than in the enzyme-containing plasma. Further in vivo pharmacokinetic research with these compounds will be required to evaluate their oral bioavailability and efficacy for affecting the endocannabinoid system.
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Al-Ohali, Hadeel. „Factors effecting primary stability of mini-implants in vitro“. Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62763.
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Objectives: Mini-implants (MIs) are now routinely used in orthodontic treatments; however,
compared to conventional implants, MIs suffer higher failure. Achieving primary stability (PS)
appears to be the most important factor predicting success of MIs. Factors such as implant
diameter, length, and bone quality are known to influence PS in conventional implants; however,
little is known of the effects of these factors on PS in MIs. Therefore, the aim of this study was
to investigate the effect of MI’s diameter, length and the presence of cortical bone in PS.
Methods: AbsoAnchor TAD design from Dentos with 1.5,1.7, and 2mm diameters; 6,8, and
10mm length were placed in Polyurethane bone blocks with densities of cancellous bone (GP-
20). MIs were also placed in blocks were sandwiched with 1 or 2mm polyurethane sheets,
which simulated cortical bone density. Four MIs in each group were placed using recommended
procedures. PS of MIs was measured with Periotest and Osstell by three testers. The Cronbach
Alpha inter-examiners reliability test was used to evaluate agreement among the testers. PS data
were analyzed with multifactorial ANOVA to detect the significant influence of each factor in
MIs’ PS (a = 0.05).
Results: Both Osstell and Periotest indicated significant increase in PS (p<0.05) when cortical
bone sheet of 1 or 2 mm thickness were in contact with MIs. MIs’ diameter had significant
influence in PS, indicating that MIs with wider diameter (1.7-2 mm) had significantly higher PS
(p < 0.05) in both cancellous and cortical sandwiched models.
There was no significant difference in PS when different lengths of MIs were used in cortical
sandwiched models; however, an increase in MIs’ length appeared to increase PS only in soft
bone blocks, which simulated the hardness of the cancellous bone.
Conclusions: Important factors in achieving PS in MIs appear to be bone type and implant
diameter in heterogeneous bone (combined cancellous & cortical bone) often found in vivo. An
increase in the length of the MIs only improves PS in homogeneous soft bone (cancellous bone).
Recognizing factors improving PS would expect to decrease unnecessary trauma and failure rate
in children and adolescence.Dentistry, Faculty of
Graduate
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Becker, Kimberly N. „In vitro stability and pharmacokinetics of novel antileishmanial compounds“. Connect to resource, 2007. http://hdl.handle.net/1811/25192.
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Thesis (Honors)--Ohio State University, 2007.Title from first page of PDF file. Document formatted into pages: contains 12 p.; also includes graphics. Includes bibliographical references (p. 12). Available online via Ohio State University's Knowledge Bank.
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Patel, Ramila. „Delivery and stability of antisense oligonucleotide conjugates in vitro“. Thesis, Aston University, 1998. http://publications.aston.ac.uk/10983/.
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The aim of this project was to study the delivery of ODNs to macrophages and to assess the stability of two ODN conjugates, in vitro. The first conjugate aimed to improve uptake of ODNs via mannose receptor mediated delivery, the second investigated the improved delivery of ODN conjugates via non-specific lipophilic interaction with the cell membrane. A mono-mannose phosphoramidite derivative was designed and synthesised and a mono-mannose ODN conjugate synthesised by standard phosphoramidite chemistry. Delivery of this conjugate was enhanced to RAW264.7 and J774 macrophage cell lines via a mechanism of receptor mediated endocytosis. The delivery of three lipophilic ODN conjugates, cholesterol (cholhex), 16-carbon alkyl chain (C16) and hexa-ethylene glycol (HEG) moieties and an unconjugated ODN were assessed in RAW264.7 macrophages. All three conjugates increased the lipophilicity of the ODN as assessed from partition coefficient data. Both the cholhex and unconjugated ODNs were found to have higher degrees of cellular association than the C16 and HEG conjugates. Cellular uptake studies implicated internalisation of these ODNs by an adsorptive endocytosis mechanism. Following endocytosis, ODNs must remain stable during their residence in endosomal/lysosomal compartments prior to exiting and exerting their biological action in either the cytosol or nucleus. Assessment of in vitro stability in a lysosomal extract revealed the cholhex conjugate and unconjugated ODNs to have a longer half-life than the C16 and HEG conjugated ODNs, highlighting the influence of conjugate moieties on lysosomal stability. The effects of base composition and length on stability in a lysosomal extract revealed the longest half-life for homo-cytidine ODNs and ODNs over 20 nucleotides in length. These studies suggest that the above conjugates can enhance cellular association and delivery of antisense ODNs to cultured macrophages. This may lead to their use in treating disorders such as HIV infection, which affects this cell type.
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Robson, Alice. „In vitro reconstitution and stability of a beta-adrenergic receptor“. Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424005.
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Costanzo, Jerry Lee. „In vitro comparison of methylene diphosphonate radiopharmaceuticals“. Scholarly Commons, 1985. https://scholarlycommons.pacific.edu/uop_etds/484.
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The radiopharmaceutical methylene diphosphonate (MDP) is a relatively new diagnostic tool and currently in widespread use as a gone imaging agent to delineate areas of altered osteogenesis. MDP is chelated with radioactive technetium-99m (Tc99m) and injected into the venous system of the body. It quickly clears from the bloodstream and is deposited into areas of bone transformation. Osteoporosis, primary carcinoma, bony metastases, osteomyelitis, and stress fractures are diagnosed with the use of Tc99m-MDP (1). In the presence of disease, the biodistribution of Tc99m-MDP is altered and this change is reflected in the images or scans. Ideally, the product would show a high ration of radioactivity in the target organ tot that of the surrounding tissue, with a minimization of radiation exposure to the patient. The purpose of this study will be to investigate Methylene Diphosphonate radiopharmaceuticals for their binding efficiencies, stability, and subsequent changes due to varying technetium levels.
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Azhakathu, Anisha Tresa. „In vitro characterization of the primary stability of acetabular hip implants“. Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18853/.
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L’artroplastica d’anca è un’operazione chirurgica che consiste nella sostituzione dell’articolazione del bacino con una protesi artificiale. Più del 50% dei casi di fallimento dell’impianto è dovuto alla mobilizzazione asettica della componente acetabolare. La stabilità primaria di un impianto è la sua capacità di resistere ai micromovimenti che si verificano all’interfaccia osso-impianto nel primo periodo post-operatorio ed è un aspetto fondamentale che caratterizza la vita a lungo periodo dell’impianto. In questa tesi è stato fatto un confronto della stabilità primaria della componente acetabolare dopo due diversi impianti eseguiti con tecniche diverse. Lo studio è stato svolto su dieci emi pelvi da donatori umani. Durante il primo impianto l’obiettivo era quello di ripristinare il centro di rotazione dell’acetabolo nativo. Successivamente, i provini impiantati sono stati testati su una macchina di prova, simulato una condizione semplificata di standing-up. L’utilizzo della Digital Image Correlation ha permesso l’acquisizione di immagini cui elaborazione ha fornito informazioni sui micromovimenti all’interfaccia osso-protesi e sulla distribuzione delle deformazioni sulla superficie ossea. Dopo aver testato i provini per la prima volta, la protesi è stata estratta e ri-impiantata dopo aver fresato l’acetabolo fino a raggiugere la base (lamina quadrilatera). Dopo il secondo impianto, è stata ripetuta la procedura di test con carichi crescenti e medesimo criterio d’arresto. Il confronto tra i micromovimenti all’interfaccia non ha evidenziato differenze statisticamente rilevanti tra le due tecniche di impianto. L’analisi delle deformazioni ha evidenziato differenze statisticamente rilevanti solo tra le deformazioni principali minime. Considerando che la stabilità primaria di un impianto dipende principalmente dai micromovimenti all’interfaccia, si può concludere che non ci sono differenze rilevanti tra le due tecniche di impianto.
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Potter, Robert Henry. „Genetic stability of potato (Solanum tuberosum L.) after in vitro culture“. Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46510.
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Woodward, G. „Anthocyanin stability, metabolic conjugation and in vitro modulation of endothelial superoxide production“. Thesis, University of East Anglia, 2010. https://ueaeprints.uea.ac.uk/25829/.
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Nieuwoudt, Stephnie. „Preparation, stability and in vitro evaluation of liposomes containing chloroquine / Stephnie Nieuwoudt“. Thesis, North-West University, 2010. http://hdl.handle.net/10394/4740.
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Malaria is currently a huge treat worldwide, as far as infections are concerned, and is
responsible for thousands of deaths per annum. The dilemma associated with the development
of anti–malarial drug resistance over the past few decades should be addressed as a matter of
urgency. Novel drug delivery systems should be developed in order to employ new and existing
anti–malarial drugs in the treatment and management of malaria. The aim of these delivery
systems should include an improvement in the efficacy, specificity, acceptability and therapeutic
index of anti–malarial drugs.
Previous studies have suggested that liposomes have the ability to encapsulate, protect and to
promote the sustained release of anti–malarial drugs. Two liposome formulations, namely
liposomes and chloroquine entrapped in liposomes, were formulated during this thesis and
evaluated by conducting a stability study and an in vitro study with the main focus on cell
viability.
The stability study consisted of a series of stability tests regarding the stability of nine liposome
and nine chloroquine entrapped in liposome formulations over a period of twelve weeks. The in
vitro study included three assays such as a reactive oxygen species assay, a lipid peroxidation
assay and a hemolysis assay. The aims of these studies included the manufacturing of
liposomes, the incorporation of chloroquine into liposomes, the determination of the stability of
the formulations as well as the evaluation of the possible in vitro toxicity of liposomes.
Results obtained from these studies revealed that liposomes remained more stable over the
stability study period in comparison to chloroquine entrapped in liposomes. The entrapment of
chloroquine within liposomes was possible, although the initial entrapment efficiency (%) of
14.55 % was much too low. The production of reactive oxygen species occurred to a small
extent in the red blood cells and the infected red blood cells. Equal amounts of reactive oxygen
species (%) was observed within both the red blood cells and the infected red blood cells with a
maximum value of 23.27 % in the presence of the chloroquine entrapped in liposomes at
varying concentrations. Red blood cells experienced the highest degree of lipid peroxidation
(%) in the presence of chloroquine, at varying concentrations, entrapped in liposomes. The
maximum amount of lipid peroxidation (%) was 79.61 %. No significant degree of hemolysis
(%) was observed in the red blood cells neither in the presence of the liposomes nor in the
presence of the chloroquine entrapped in liposomes at varying concentrations.
It can be concluded that liposomes are a more stable formulation and have less toxic effects on
red blood cells and infected red blood cells in comparison to the chloroquine entrapped in liposome formulations. Future studies should investigate the possibility of a more stable and
less toxic chloroquine entrapped in liposome formulation.Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.
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Zhang, Xiaoqin. „Polysialylated liposomes : preparation, characterisation and stability studies in vitro and in vivo“. Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313513.
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DI, FELICIANTONIO MARINA. „Studio in vitro sulla stabilità strutturale dei cannabinoidi sintetici nel fluido orale“. Doctoral thesis, Università Politecnica delle Marche, 2018. http://hdl.handle.net/11566/253005.
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Nell’ultimo decennio il mercato clandestino delle droghe d’abuso ha visto la nascita,
prima, e l’affermazione, poi, di sostanze sintetiche molto più pericolose delle droghe
tradizionali. Nel 2012 la Commission on Narcotic Drugs le ha classificate con il
termine di NPS o “Nuove Sostanze Psicoattive”, legalmente commercializzate come
profumatori ambientali denominati “Spice”. Risultati chimico-tossicologici hanno
evidenziato la presenza, in questi prodotti, di cannabinoidi sintetici particolarmente
affini ai recettori dei cannabinoidi CB1.
Obiettivo della Ricerca è stato quello di valutare la stabilità strutturale di queste
molecole quando sottoposte ad un cambiamento dello stato fisico dovuto alle alte
temperature raggiunte durante il processo di fumo. L’attenzione è stata richiamata
dalla saliva, matrice biologica immediatamente interessata nel processo di fumo,
caratterizzata da prelievo non invasivo e che ha permesso l’ottenimento di dati certi e
ripetibili in spettrometria di massa ad alta risoluzione. La struttura altamente
lipofilica delle molecole impone l’uso di contenitori in vetro, al fine di evitarne
l’adsorbimento sulla superficie delle provette in polipropilene, mentre la temperatura
di conservazione a cui è sottoposta la matrice biologica influisce sulla potenziale
degradazione dei cannabinoidi sintetici ad opera degli enzimi salivari e/o microbici. I
risultati ottenuti evidenziano una stabilità strutturale certa delle molecole sottoposte
ad indagine, ma il dato analitico ottenuto, utilizzabile sia in ambito clinico che
forense, deve rispettare un rigido protocollo analitico/strumentale.In the last decade the illegal drug market has seen the birth, first, and the affirmation, then, of synthetic substances much more dangerous than traditional drugs. In 2012 the Commission on Narcotic Drugs classified them under the term NPS or "New Psychoactive Substances", legally marketed as environmental fragrances named "Spice". Chemical-toxicological results have highlighted the presence, in this products, of synthetic cannabinoids particularly affine to CB1 cannabinoid receptors. The aim of the research was to evaluate the structural stability of these molecules when subjected to a change of the physical state due to the high temperatures reached during the smoking process. The attention was drawn to saliva, the biological matrix immediately involved in the smoking process, characterized by non-invasive sampling and which allowed obtaining reliable and repeatable data in high-resolution mass spectrometry. The highly lipophilic structure of the molecules requires the use of glass containers, in order to avoid adsorption on the surface of polypropylene tubes, while the storage temperature to which the biological matrix is subjected influences the potential degradation of synthetic cannabinoids by salivary and/or microbial enzymes. The results obtained show a certain structural stability of the molecules under investigation, but the analytical data obtained, usable both in the clinical and forensic field, must comply with a strict analytical/instrumental protocol.
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Leib, Nicholas. „Modélisation du comportement impactant d'un ensemble câble-gaine dans le domaine fréquentiel : Application aux commandes à câbles“. Ecully, Ecole centrale de Lyon, 2008. http://bibli.ec-lyon.fr/exl-doc/TH_T2151_nleib.pdf.
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Dans cette thèse nous étudions le comportement vibratoire des commandes à câbles d’une boîte de vitesses automobile. La présence de jeux, qui assurent le montage et le fonctionnement de ces commandes, créent des vibro-impacts qui ont des répercussions acoustiques, appelées grésillement, négatives pour le conducteur. L’objectif de cette thèse, réalisée en collaboration avec PSA Peugeot-Citroën, est de comprendre l’origine du grésillement, et de prédire son apparition dans les différentes configurations véhicules. Dans un premier temps, nous traiterons les diverses méthodes qui existent pour résoudre le problème non-linéaire dans le domaine fréquentiel. Nous proposerons une démarche pour établir la réponse en fréquence sur la plage de fonctionnement du moteur, et une approche pour estimer le contenu spectral hautes fréquences à la suite d’un calcul par balance harmonique. Ces méthodes sont appliquées sur un modèle vibro-impactant simplifié. Dans un second temps, nous présenterons les divers essais qui ont permis de déterminer l’origine vibratoire du grésillement, d’identifier les caractéristiques matériaux nécessaires et d’établir une référence pour valider un modèle. Ensuite, un modèle éléments finis et les résultats de corrélation sont présentés. Nous proposons alors un critère qui permet d’établir rapidement si le système va grésiller ou non. Ce critère est enfin utilisé pour comparer le niveau de grésillement sur plusieurs configurations véhiculesIn this thesis we study the dynamic behavior of a vehicle’s gearshift cables. To ensure proper assembly and functioning of the pieces, there are clearances in the system. The latter cause a vibro-impacting phenomenon, called tizzing, that can bother the driver. The aim of this work, done in collaboration with PSA Peugeot-Citroën, is to understand the sources of cable tizzing, and predict its presence in different configurations. The first part is devoted to presenting the different methods used to solve a nonlinear problem in the frequency domain. A method to determine the frequency response on a car motor’s bandwidth is presented and an approach to estimate the high frequency content after a harmonic balance is proposed. These methods are applied on a simple vibro-impacting system. The next part presents the different experiments that were conducted to determine the source of cable tizzing and identify the physical characteristics of the cable and its protective housing. A experimental testbench served as a reference to validate a finite element model. Then, the model is presented and the correlation results are shown. A criterion is proposed and helps establish whether or not, the system is going to tizz. Finally, the latter is used to compare the tizzing level on different vehicle configurations
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Maccari, Flavia Lima Ribeiro [UNESP]. „Avaliação da atividade antiproliferativa in vitro, liberação, permeação e retenção cutânea in vitro e estabilidade de emulsões contendo (-)- Terpinen-4-OL“. Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/96248.
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Made available in DSpace on 2014-06-11T19:28:04Z (GMT). No. of bitstreams: 0
Previous issue date: 2011-04-08Bitstream added on 2014-06-13T18:57:11Z : No. of bitstreams: 1
maccari_flr_me_arafcf.pdf: 1400540 bytes, checksum: 7bc406a11537837c7f75cdf60b68c782 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Universidade Estadual Paulista (UNESP)
O terpinen-4-ol é o principal componente da M. alternifólia, apresenta atividade antiinflamatória, antibacteriana e antifúngica; em estudos recentes in vitro a atividade antineoplásica para linhagens celulares de melanoma (M14) foi demonstrada. O objetivo específico deste trabalho foi verificar a atividade farmacológica in vitro dos isômeros óticos (-) terpinen-4-ol e (+) terpinen-4-ol e do óleo de Melaleuca alternifolia em nove linhagens diferentes de células tumorais, incluindo a célula UACC-62 do melanoma que ainda não havia sido estudada, e a concentração eficaz para o desenvolvimento de formulação que possa ter ação contra o melanoma. Após realização dos ensaios farmacológicos in vitro verificou-se que o (-)terpinen-4-ol apresentou melhor atividade nas linhagens celulares de melanoma, sendo o princípio ativo de escolha para as duas formulações que foram desenvolvidas, testadas e comprovadas a qualidade e estabilidade. Para caracterização das formulações foram efetuados os ensaios reológicos, sendo comprovado que as emulsões desenvolvidas são adequadas para o uso tópico no que diz respeito às suas características reológicas, sendo que as duas apresentaram comportamento de fluxo semelhante, diferindo apenas na área de histerese. Posteriormente foram feitos testes de permeação e retenção cutânea in vitro, para verificar qual formulação permite que o princípio ativo atinja em maior concentração a camada de interesse para atividade contra o melanoma. O método proposto para quantificação do (-)-terpinen-4-ol foi validado e utilizado nos ensaios de estabilidade acelerada, liberação, permeação e retenção cutânea in vitro. Os ensaios de liberação demonstraram que as duas formulações apresentam cinética de zero ordem, com fluxo de 14,62 µg/cm2 /h para formulação 1 e de 6,70 µg/cm2 /h para formulação F2. Na retenção cutânea...
The terpinen-4-ol is the major component of M. alternifolia, has anti-inflammatory, antibacterial and antifungal, in recent studies in vitro anticancer activity for melanoma cell lines (M14) was demonstrated. The specific objective of this study was to assess the in vitro pharmacological activity of optical isomers (-) terpinen-4-ol and (+) terpinen-4-ol and oil of Melaleuca alternifolia in nine different tumor cell lines, including cell UACC -62 melanoma that had not yet been studied, and effective concentration for the formulation development that may have action against melanoma. After performing the in vitro pharmacological tests showed that the (-) terpinen-4-ol showed better activity in melanoma cell lines, with the active ingredient of choice for the two formulations were developed, tested and proven quality and stability. For characterization of the formulations were made the rheological tests and confirmed that the developed emulsions are suitable for topical use in relation to their rheological characteristics, and the two had similar flow behavior, differing only in the area of hysteresis. Subsequent tests were performed permeation and skin retention in vitro, to determine which formulation allows the active ingredient reaches higher concentration in the layer of interest for activity against melanoma. The proposed method for quantification of (-)-terpinen-4-ol was validated and used in accelerated stability testing, release, skin permeation and retention in vitro. The release assays demonstrated that both formulations have zero order kinetics at a rate of 14.62 g/cm2/h for formulation 1 and 6.70 g/cm2/h for formulation F2. In vitro skin retention was found that the F1 showed retention of terpinen-4-ol smaller in the stratum corneum, compared to F2. Conversely, the retention in the epidermis over the dermis of terpinen-4-ol was higher in F1. It was found that formulation F1 ... (Complete abstract click electronic access below)
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Omer, Khaled A. E. „An in-vitro evaluation of resonant frequency analysis to measure fixed bridge stability“. Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.570458.
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Conventional fixed bridge prostheses may fail due to one or more loose retainers, which may be difficult to diagnose. An objective and reproducible investigation to identify, at an early stage, loosening of a retainer could be of significant benefit. The aims of the current series of investigations were to record retrospectively the clinical performance of different types of conventional fixed prostheses used to replace missing teeth and to determine whether Resonance Frequency Analysis (RFA) was capable of measuring bridge stability, in-vitro. One hundred and twenty two patients with 168 bridges were referred to two consultants at the Department of Restorative Dentistry at Liverpool Dental Hospital between Jan 2004 - Dec 2008 with fixed prosthesis problems. Fixed-fixed designs were the most common (77.9%), with cantilever bridges constituting 19.0% of the total. The most frequent cause of failure (39.0%) was associated with a post and core abutment. Apical pathology was found in 20.2%, dental caries in 14.8% and loss of retention in 11.9%. Fixed-fixed bridges were therefore chosen for further study. In-vitro pilot studies were subsequently undertaken to determine the feasibility of using resonance frequency analysis (RFA) on all-metal fixed-fixed bridges affixed to different models (wholly dental stone, or incorporating a simulated periodontal ligament) and to determine a reliable method to record this using an Osstell Mentor apparatus. The use of a buccal approach to record RF A values was validated. Based on the results from the pilot studies and a subsequent power analysis to set sample size, 100 models with standardised acrylic tooth abutment analogues and simulated periodontal ligaments were fabricated. All-metal fixed-fixed bridges were constructed from the first molar to the first premolar using standardised methods on models based with dental stone to mimic 100% (n=SO) or SO% (n=SO) bone support. In each case, two equal groups of 2S specimens had either both retainers cemented, (control group) or the premolar left uncemented (test group) to mimic clinical failure, cemented by a second operator to allow blind analysis. A magnetic component (Smartpeg) was subsequently cemented to the bridge using low-shrink composite resin and the Osstell Mentor used to measure bridge stability expressed as Bridge Stability Quotients (BSQ). The BSQ recorded at the premolar site in both 100% and SO% bone support models demonstrated a highly statistical significant difference (p<0.003) between the control and test groups. ROC analysis determined that a cut-off point was BSQ >60 suggesting that the fixed bridge was stable (cemented to both abutments) whereas a BSQ >59 indicated a risk of the bridge being uncemented to the premolar. All 100% bone support models were subsequently tested to failure in tension using a Universal Testing Machine with a SOO (N) load cell and cross-head speed of 10mm/min. 37% of specimens from the control group debonded at loads between 82 to 120N with the other 63% failing through extraction of the analogue/fracture of the model. 89.2% of the test group specimens failed by extraction of the tooth analogue from one or both ends at loads below SON. Statistical analysis using Kruskal Wallis tests demonstrated that the destructive testing could detect a highly statistically significant difference between the test and control group (P<0.0001) These investigations identified mechanical and biological factors associated with failure of conventional fixed bridges and demonstrated that resonance frequency analysis measurements was able to identify, reliably and non-destructively, stable bridges and those with one retainer uncemented, in-vitro. With further developments of the technique it may be possible to identify fixed-fixed bridge failure clinically and provide appropriate early clinical intervention.
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Scholtz, Jacques Coenraad. „Preparation, stability and in vitro evaluation of liposomes containing amodiaquine / Jacques C. Scholtz“. Thesis, North-West University, 2010. http://hdl.handle.net/10394/4878.
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Malaria is a curable disease that claims nearly one million lives each year. Problems with the treatment of malaria arise as resistance spreads and new treatment options are becoming less effective. The need for new treatments are of the utmost importance. Liposomes combined with antimalarials are a new avenue for research as liposomes can increase the efficacy of drugs against pathogens, as well as decreasing toxicity. Amodiaquine is a drug with known toxicity issues, but has proven to be effective and is, therefore, a prime candidate to be incorporated into the liposomal drug delivery system.
The aim of this study was to prepare, characterize and evaluate the toxicity of the liposomes with incorporated amodiaquine. The solubility of amodiaquine was determined and liposomes formulated with, and without, amodiaquine entrapped. Accelerated stability studies (at 5 'C, 25 'C with relative humidity of 60% and 40 'C with a relative humidity of 40%) were conducted during which the size, pH, morphology and the entrapment efficacy was determined. The toxicity was determined in vitro by analysing the levels of reactive oxidative species and lipid peroxidation caused by the formulations to erythrocytes infected with P. falciparum as well as uninfected erythrocytes with flow cytometry.
The solubility study of amodiaquine in different pH buffers showed that amodiaquine was more soluble at lower pH values. Solubility in solution with pH 4.5 was 36.3359 ± 0.7904mg/ml when compared to the solubility at pH 6.8, which was 15.6052 ± 1.1126 mg/ml. A buffer with a pH of 6 was used to ensure adequate solubility and acceptable compatibility with cells. Liposomes with incorporated amodiaquine were formulated with entrapment efficacies starting at 29.038 ± 2.599% and increasing to 51.914 ± 1.683%. The accelerated stability studies showed the median sizes and span values remained constant for both liposome and amodiaquine incorporated liposomes at 5 'C. The higher temperatures, i.e. 25 'C and 40 'C, displayed increases in the median size, and decreases in the span for both formulations. The conclusion can, therefore, be made that both liposome and amodiaquine incorporated liposomes are stable at lower temperatures. The entrapment efficacy increased from initial values to nearly 100% during the course of the stability study. This was attributed to amodiaquine precipitating from the solution. The pH values of the liposomes and amodiaquine incorporated liposomes remained constant for each formulation; though the amodiaquine incorporated liposomes had a lower starting pH, the formulations are both thought to be stable in terms of the pH.
Toxicity studies revealed low levels of reactive oxygen species as well as low levels of lipid peroxidation for both liposome and amodiaquine incorporated liposomes, on both erythrocyte and Plasmodium infected erythrocytes. From the toxicity studies it can be concluded that liposomes and amodiaquine incorporated liposomes are not toxic to erythrocytes and infected erythrocytes.
It was concluded that liposomes incorporating amodiaquine could possibly be used as a treatment option for malaria.Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.
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Ferreira, Pedro Garcia. „Insights into human carboxylesterase 2 stability and activity in vivo and in vitro“. Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8141.
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Dissertation to obtain a Master Degree in BiotechnologyDue to its role in ester containing xenobiotics metabolization, such as the activation of pro-drugs, carboxylesterase 2 (CES2) has become an attractive enzyme, with potential applications in the field of chemotherapy. Still, it hasn’t been as thoroughly characterized as the other main human carboxylesterase, the carboxylesterase 1 (CES1), having no described structure yet. The original hypothesis being tested in this work was the possibility of enzyme-enzyme interaction that had been suggested from previous work in the host laboratory. The initial task of this project was therefore to further assess CES2 stability and to test possible enzyme-enzyme interaction with CES1, by characterizing enzyme hydrolytic kinetics in different assay conditions and evaluating the behaviour of enzyme mixtures. Different CES2 activity rates were observed when tested in different reaction conditions suggesting a stabilizing/destabilizing effect on the enzyme, but evidence of in vitro interactions was not confirmed. Considering the dependence of conclusions on test methods as well as the extreme care measures that have to be taken for avoiding enzyme degradation during the preparation of cell extracts, a second goal was envisaged for this project. This consisted in the development of a new method capable of determining CES activity in conditions closer to those that are found physiologically. A new spectrofluorometric method able to assess carboxylesterase activity in intact living cells, using loperamide as a specific CES2 inhibitor and Bis(4-nitrophenyl) phosphate as a total carboxylesterase inhibitor was therefore developed and applied to Caco-2, HT-29. Hep G2 and HEK-293T cell lines. The method proved itself capable of detecting CES total activity in living cells, as well as to differentiate between CES2 and other CES activities. Differences were shown between this and the traditional methods using cell extracts, suggesting that the latter may not be the best option when trying to predict in vivo CES behavior.
Fundação para a Ciência e Tecnologia - (PTDC/EBB-BIO/111530/2009, PEst-OE/EQB/LA0004/2011)
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Lai, Stephen Val. „EFFECTS OF CELL PASSAGE IN VITRO ON THE STABILITY OF TUMOR KARYOTYPE (CANCER)“. Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275311.
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Tirand, Loraine. „Ciblage de neuropiline-1, co-récepteur du VEGF, pour potentialiser l'effet anti-vasculaire de la Thérapie PhotodynamiqueUne étude de stabilité de la molécule conjuguée a été réalisée in vitro et in vivo. Si le peptide est relativement stable jusqu'à 4h après injection intraveineuse in vivo, l'utilisation de pseudo-peptides plus résistants aux peptidases permettrait une efficacité encore supérieure“. Phd thesis, Université Henri Poincaré - Nancy I, 2007. http://tel.archives-ouvertes.fr/tel-00198834.
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La croissance d'une tumeur au-delà de quelques mm3 requiert la formation de son propre réseau vasculaire par angiogenèse ; la destruction de ces vaisseaux nourriciers pourrait conduire à une régression tumorale. L'angiogenèse est orchestrée par de nombreux facteurs de croissance, dont le VEGF (Vascular Endothelial Growth Factor). La thérapie photodynamique (PDT) est une modalité de traitement des petites tumeurs localisées, reposant sur l'action conjuguée d'un photosensibilisateur (PS), de la lumière et de l'oxygène. Outre des dommages cytotoxiques directs aux cellules tumorales, la PDT induit des dommages indirects, caractérisés par l'altération de la vascularisation tumorale et l'activation d'effecteurs immunitaires. Un nouveau PS couplé à un heptapeptide (ATWLPPR) ciblant neuropiline-1, un co-récepteur du VEGF, a été synthétisé. Ce couplage ne modifie pas les propriétés photophysiques du PS.
Une étude in vitro sur cellules endothéliales de veine ombilicale humaine a montré une moindre cytotoxité à l'obscurité, une amélioration de l'incorporation intracellulaire et une meilleure activité photodynamique, suite au couplage du PS au peptide.
In vivo, chez des souris nude porteuses de gliomes malins humains, le PS conjugué s'accumule dans la tumeur à des taux supérieurs à ceux retrouvés dans la peau. En utilisant des conditions (dose de PS, fluence et irradiance lumineuses) optimisées par une approche de plan d'expériences, la PDT avec le PS couplé au peptide induit une réduction du flux sanguin pendant traitement, comparé au PS non couplé, une destruction des cellules endothéliales des vaisseaux sanguins, 24h après PDT, ainsi qu'un retard de croissance tumorale, statistiquement significatif comparé au PS non couplé.
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Baby, André Rolim. „Avaliação in vitro da permeabilidade cutânea da rutina em emulsões cosméticas“. Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-25102013-153334/.
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A rutina é empregada como antioxidante e na prevenção da fragilidade capilar. Pode ser veiculada em emulsões tópicas adequadas para atingir o local de ação. Estudos de penetração in vitro através da pele humana seria a situação ideal, entretanto, há dificuldades de sua obtenção e manutenção de sua viabilidade. Entre os demais modelos de membrana, a muda de pele de cobra apresenta-se como estrato córneo puro, fornecendo barreira similar ao humano e é obtida sem a morte do animal. Os objetivos desta pesquisa foram: (1) desenvolver e avaliar a estabilidade de emulsões cosméticas, contendo rutina e promotores de penetração cutânea, tais como, uréia (U), isopropanol (IP) e propilenoglicol (PG); (2) avaliar a liberação da referida substância ativa das emulsões e; (3) avaliar a penetração e a retenção cutânea in vitro da rutina da formulação de melhor desempenho. Emulsões foram desenvolvidas com rutina a 5,0% p/p e U, IP e PG, associados ou não e em proporções distintas, segundo planejamento fatorial com dois níveis com ponto central. Quantificou-se a rutina das emulsões por espectrofotometria a 361,0 nm, método previamente validado. A liberação da rutina nas formulações foi realizada em células de difusão vertical com membrana de acetato de celulose e água destilada e álcool etílico absoluto 99,5% (1:1), como fluido receptor. O experimento foi conduzido em um período de seis horas, a 37,0 ±. 0,5 °C e agitação constante de 300 rpm.>f. emulsão de melhor desempenho quanto à liberação foi estudada quanto à estabilidade (Testes de Estabilidade Acelerada). Para o estudo de penetração e retenção cutânea da rutina dessa formulação foi utilizada muda de pele de cobra de Crotalus durissus. Empregou-se o método espectrofotométrico validado a 410,0 nm para a quantificação da rutina após liberação, penetração e retenção cutânea. Todas as emulsões foram consideradas adequadas após desenvolvimento das formulações. A uréia (isolada e em associação com IP e PG) e o isopropanol (isolado e em associação com PG) influenciaram negativamente a liberação da rutina das emulsões em diversos parâmetros. A rutina liberada e acumulada da formulação contendo PG a 5,0% p/p possuiu valor de 648,80 ±. 53,01 µg/cm2. Fora do esperado, a preparação contendo o número maior de promotores (U 5,0% p/p, IP 5,0% p/p e PG 5,0% p/p) resultou em liberação de menor magnitude igual a 419,76 ±. 17,98 µg/cm2. A presença do PG apresentou-se mais eficiente na liberação da rutina, mas não na sua penetração através da muda de pele de C. durissus, retendo 0,931 ± 0,0391 µg de rutina/mg de muda de pele de cobra. Nas condições de armazenamento a 25,0 ±2,0 °C; 5,0 ±0,5 °C e 45,0 ±. 0,5 °C, a emulsão com PG e rutina apresentou-se quimicamente estável durante 30 dias. De acordo com os resultados, a emulsão contendo PG apresentou liberação mais expressiva da rutina, no entanto, não ocorreu a penetração cutânea, mas apenas sua retenção no estrato córneo de C. durissus. A preparação manteve-se estável em todas as condições de armazenamento.Rutin is employed as antioxidant and to prevent the capillary fragility and, when incorporated in cosmetic emulsions, it must target the action site. In vitro cutaneous penetration studies through human skin is the ideal situation, however, there are difficulties to obtain and to maintain this tissue viability. Among the membrane models, the shed snake skin presents itself as pure stratum corneum, providing barrier function similar to human and it is obtained without the animal sacrifica. The objectives of this research were: (1) development and stability evaluation of cosmetic emulsions containing rutin and penetration enhancers, as urea (U), isopropanol (IP) and propylene glycol (PG); (2) release evaluation of the mentioned active substance from the emulsions and; (3) evaluation of rutin in vitro cutaneous penetration and retention from the emulsion of the best performance. Emulsions were developed with rutin 5.0% w/wand U, IP and PG, associated or not according to factorial design with two levels and central point. Active substance on the formulations was quantified by a validated spectrophotometric method at 361.0 nm. Rutin release from emulsions was performed in vertical diffusion cells with cellulose acetate membrane and distilled water and ethanol 99.5% (1:1), as receptor fluid. The experiment was conducted for six hours, at 37.0 ± 0.5 °c with constant stirring of 300 rpm. Formulation with best profile of rutin release had its stability studied by the Accelerated Stability Assays. Rutin cutaneous penetration and retention from the mentioned emulsion was performed with shed snake skin from Crotalus durissus. Spectrophotometry at 410.0 nm, previously validated, determined the active substance after release and cutaneous penetration/retention. Ali emulsions were considered apparently stables after development. Urea (isolated and associated with IP and PG) and isopropanol (isolated and associated with PG) have influenced negatively the rutin release in several parameters. Emulsion with PG 5.0% w/w presented rutin released and accumulated equal to 648.80 ± 53.01 µg/cm2. Unexpectedly, the formulation containing all enhancers (U 5.0% w/w, IP 5.0% w/w and PG 5.0% w/w) has decreased the amount released of the active substance (419.76 ± 17.98 µg/cm2). Emulsion with PG presented more adequate for rutin release, but PG did not provide rutin cutaneous penetration through C. durissus skin, retaining 0.931 ± 0.0391 &$181;g rutin/mg shed snake skin. The referred formulation was chemically stable for 30 days after they have been stored at 25.0 ± 2.0 °c, 5.0 ± 0.5 °c and 45.0 ± 0.5 °C. In conclusion, emulsion with PG provided rutin release more expressively, although, it has not been verified the active cutaneous penetration, but only its retention on the Crotalus durissus stratum corneum. Formulation was stable in all storage conditions.
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Linsalata, Mariateresa. „In vitro assessment of the primary stability of the acetabular component in hip arthroplasty“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15551/.
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In Europa, più di 700'000 interventi di artroplastica d’anca vengono effettuati annualmente. Il tasso di fallimento della chirurgia è del 2-8 % (a 10 anni). Di questo, più del 50% è dovuto alla mobilizzazione asettica della componente acetabolare (più che ad un fallimento legato alla componente femorale). Lo scopo centrale di questo progetto di tesi è quello di creare un pilot-test per la valutazione in vitro della stabilità primaria di una componente acetabolare commerciale, impiantata in una emipelvi sintetica (senza cemento, attraverso la procedura chirurgica press-fit). La valutazione dei micromovimenti prevede un approccio multiplo, costituito dall’utilizzo della Digital Image Correlation (DIC) e di sensori lineari di spostamento. Per adeguare e migliorare le prestazioni dei due strumenti di misura, lo studio prevede: (1.a) l’ottimizzazione delle misure ottenute dalla correlazione di immagini, (1.b) creare ed effettuare la procedura di calibrazione interna dei sensori di spostamento e l’ottimizzazione delle misure ottenute dai sensori stessi come monitor dell’intero pilot-test. La seconda parte del lavoro si prone di implementare una metodologia affidabile per il calcolo delle roto-traslazioni relative tra coppa e osso. La creazione di un algoritmo dedicato, prevede, quindi, di valutare: (2.a) la migrazione permanente e (2.b) i micromovimenti inducibili dai picchi di carico.L’utilizzo della correlazione di immagini è risultato un gran punto di forza dello studio. Grazie al potere della DIC nell’elaborare spostamenti e deformazioni a tutto campo, senza contatto e in stereofotogrammetria, per la prima volta è stato possibile ottenere informazioni 3D del vettore migrazione della coppa. Inoltre, creando una procedura ottimizzata dell’allineamento del provino sotto la macchina, si sono potute riferire tutte le misure ottenute dal pilot-test, all’Aneterior Pelvic Plane (sistema di riferimento di rilevanza clinica).
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Bicknell, Ryan T. „All-metal glenoid component design in shoulder arthroplasty, an in vitro implant stability study“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30757.pdf.
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Watson, Neil Michael. „The design and synthesis of polyvalent gene delivery vehicles and polyplex stability in vitro“. Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435115.
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Nguyen, Minhthy Le. „Physical and Chemical Stability of All-Trans Lycopene and Other Tomato Carotenoids in Vitro“. The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392643300.
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Morosato, Federico <1991>. „In vitro biomechanical testing of the stability of primary and revision hip acetabular implants“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9394/1/Morosato_Federico_tesi.pdf.
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Hip acetabular stability is the capability of acetabular implants to resist to the forces acting in the acetabulum during patient activities after surgery. If implant motions are sufficiently low, primary stability is achieved and the osteointegration process between the implant and the surrounding bone may occur. In this context, measuring implant motions is essential to predict the implant failure. In clinical practise, these measurements are limited to implant migration, while elastic motions and periacetabular strains are not monitored. So far, to obtain a complete set of stability measurements in vitro testing is the most reliable option. Despite the importance of the experimental analysis, a general consensus about the application of biomechanical tools to solve clinical problems is still missing.
The aim of my Ph.D project was to develop and apply reliable in vitro methods to assess the hip acetabular stability in case of primary and revision reconstructions.
First, two methodological studies were conducted (1) to define and implement a robust reference frame for the human hemipelvis based on a morphological analysis of this anatomical district and (2) to create a robust procedure to measure the implant motions and the periacetabular strains with the Digital Image Correlation technique. Secondly, I applied these methods to answer the following clinical questions:
1. How do changes in the motor task affect the cup stability and the periacetabular strains?
2. Does the cup medialization affect implant stability?
3. Which is the effect on cup stability of defect reconstructions with an innovative synthetic bone substitute or with human bone graft in revision surgery?
All these clinical questions were answered in three experimental studies.
In conclusion, this project provided a reliable set of in vitro methods to perform biomechanical testing on human hemipelvis and to assess the stability of acetabular reconstructions by mean of Digital Image Correlation.
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Botti, Laura Costa Moreira 1967. „Propriedades de barreira em sistemas de embalagem para azeite de oliva“. [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255958.
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Orientador: Carlos Alberto Rodrigues AnjosDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-25T04:26:54Z (GMT). No. of bitstreams: 1 Botti_LauraCostaMoreira_M.pdf: 1490815 bytes, checksum: dc0cfefc2c575ceab1d1f3b15b4e0ec6 (MD5) Previous issue date: 2014
Resumo: Considerada a principal causa de perda da qualidade em óleos e gorduras, a oxidação leva à formação de sabores e odores indesejáveis, perda de funcionalidade e valor nutricional em especial do azeite de oliva (AO). Assim, o objetivo deste trabalho foi avaliar a eficiência de embalagens de vidro (transparente e âmbar) e polietileno tereftalato (PET) aliado à tecnologia de barreira ao oxigênio e à radiação UV, como opção à manutenção da estabilidade do AO. Inicialmente foi feita a caracterização dos materiais, seguida do envase das amostras e estocagem de metade delas em caixas de papelão mantidas na ausência de luz. Ao mesmo tempo, a outra metade foi exposta à iluminação intermitente por períodos de 12h e intensidade luminosa de 1000 lux durante seis meses. Ao longo do tempo foram feitas as seguintes análises: acidez, índice de peróxido, cor L*a*b*, cor Lovibond, extinção específica a 232 (K232) e 270nm (K270), clorofila, carotenoides, fenóis totais e ?-tocoferol. Durante o período analisado, houve aumento da acidez, índice de peróxido, K232 e K270 para todas as amostras, sendo as embalagens convencionais transparentes as mais susceptíveis e a condição sob iluminação a mais crítica. Em contrapartida, a cor, o teor de clorofila, carotenoides e fenóis totais foram reduzidos com o tempo e também sofreram influência da luz e do material de embalagem. A degradação do ?-tocoferol foi influenciada até o segundo mês pelas condições de estocagem e tipo de material da embalagem. A partir de então, os índices de tocoferol foram reduzidos de forma drástica em todos os sistemas de embalagem e provavelmente não foram detectados pela metodologia. De forma geral, sob o abrigo da luz, tanto a embalagem de PET com barreira ao oxigênio como o vidro foram efetivas nos primeiros meses, mostrando-se como opção para produtos que não necessitem de elevada proteção. Entretanto, a embalagem de vidro âmbar mostrou-se a mais eficiente devido a suas características intrínsecas e ao amplo espectro de proteção para amostras quando expostas à luz. A partir dos resultados, conclui-se que aditivos do tipo estabilizantes de radiação UV não foram efetivos nas condições de estudo, porém o uso de absorvedores de oxigênio aliado a tecnologia de blendas pode ser uma alternativa para a área de embalagens de azeite e óleos. Assim, é essencial que se pense no uso complementar de diferentes tecnologias em prol da manutenção da qualidade e estabilidade dos alimentos
Abstract: he oxidation is considered the main cause of quality loss in oils and, consequently, leads to the formation of undesirable flavors and odors, loss of nutritional value and functionality in particular olive oil (OO). This work aimed to evaluate the efficiency of glass containers (clear and amber) and polyethylene terephthalate (PET) combined with the improvement of oxygen barrier technology and UV radiation, as an option to maintain the stability of OO. At first, the materials were characterized, the samples were bottled and then half of them stored in cardboard boxes kept in the dark. At the same time, the other half was exposed to intermittent periods of 12 hours light and light intensity of 1000 lux for six months. Acidity, peroxide value, color L * a * b *, color Lovibond, specifc extinction at 232 (K232) and 270nm (K270), chlorophyll, carotenoids, total phenols and ? ¿ tocopherol were analyzed over time. During the reporting period, there was an increase in acidity, peroxide value, K232 and K270 for all samples, with the conventional transparent packaging being the most susceptible and the illumination condition, the most critical. In contrast, the color, chlorophyll content, carotenoids and total phenolics were reduced with time and were also affected by light and the packaging material. The degradation of ?-tocopherol was influenced by storage conditions and type of packaging material until the second month. Thereafter, the tocopherol levels were reduced drastically in all packaging systems and probably were not detected by the methodology. In general, in the dark, both the PET packaging with oxygen barrier such as glass were effective in the first months, showing as an option for products that do not require high protection. However, the amber glass packaging due to their inherent and broad-spectrum protection from light features proved to be the most efficient when exposed to light. The results evaluation of this research showed that the stabilizing additive type of UV radiation were not effective under the conditions of study, but the use of oxygen absorbers combined with blends technology can be an alternative to the oil packaging. Thus, it is essential to think about the complementary use of different technologies for the maintenance of the quality and stability of food
Mestrado
Tecnologia de Alimentos
Mestra em Tecnologia de Alimentos
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Venter, Telanie. „Formulation, in vitro release and transdermal diffusion of vitamin B3 for treatment of acne / Telanie Venter“. Thesis, North-West University, 2009. http://hdl.handle.net/10394/3984.
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Acne is an extremely common condition, affecting almost 80% of adolescents and young adults. It is an inflammatory disease, characterised by comedones, papules, pustules and sometimes cysts. Factors causing acne include enhanced sebum excretion, hypercornification of the sebaceous duct, ductal coloniazation with Propionibacterium acnes and production of inflammation (Gollnick & Cunliffe, 2003:1).
Because of the widespread use of topically applied antimicrobial agents in the treatment of inflammatory acne, resistance of disease-related micro-organisms developed. Therefore new strategies for the treatment of moderate inflammatory acne are necessary. Nicotinamide is a new approach to topical treatment of moderate inflammatory acne without the development of resistant micro-organisms (Otte et al., 2005:257).
Using the skin as an alternative route for the administration of nicotinamide for the treatment of acne, may be beneficial. When nicotinamide permeates through the skin, it is directly delivered to the dermis, the place where action is needed and better results can thus be expected after the treatment has started. Another benefit is that smaller amounts of the drug are absorbed systemically with decreased adverse reactions. Unfortunately, using the skin as an alternative route for administering drugs (transdermal drug delivery), has numerous limitations. One of these limitations is the barrier function of the skin (Naik et al., 2000:319). Because of the skin's outstanding ability to protect the body against unwanted substances from its surroundings, it is necessary to use methods to enhance drug penetration through the skin.
A new technology, named Pheroid™ technology, was used in this study to enhance penetration through the skin. This technology is based on the use of vesicular structures with no phospholipids or cholesterol to enhance penetration (Grobler et al., 2008:283). The aim of this study was to formulate four different semi-solid formulations with nicotinamide as the active ingredient, and to determine which of the formulations deliver nicotinamide best to the target site. Stability tests over a six months period were also performed on the different formulations.
A 3% nicotinamide cream, with and without Pheroid™ vesicles, and a 3% nicotinamide gel, with and without Pheroid™ vesicles, were formulated.Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2010.
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BOS, MARIE-ANDREE. „Procyanidines de tormentille : standardisation d'un extrait ; proprietes antiradicalaires ; formulations d'hydrogels : essais de stabilite et de diffusion in vitro“. Clermont-Ferrand 1, 1996. http://www.theses.fr/1996CLF1PP05.
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Moraes, Carla Aparecida Pedriali. „Síntese e avaliação da segurança in vitro da rutina e do succinato de rutina visando sua incorporação em formulações fotoprotetoras eficazes associados a filtros químicos e físico“. Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-07032013-092315/.
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A tendência atual do mercado cosmético é desenvolver produtos que contenham insumos de origem vegetal. O objetivo deste trabalho foi a aplicação da Tecnologia da Química Verde na síntese da rutina visando o aumento da estabilidade dessa em formulações cosméticas com sua eficácia antioxidante e fotoprotetora. Realizou-se a síntese química por meio da introdução de grupos carboxilatos às hidroxilas do dissacarídeo na molécula de rutina, gerando como produto final o succinato de rutina. Este derivado e/ou a rutina foram incorporados em 74 formulações-teste e, selecionadas 12 (sistemas emulsionados O/A), após serem submetidas à Avaliação Preliminar de Estabilidade (APE) e ao Teste de Estabilidade Acelerada (TEA), sob variações de temperatura e umidade. Utilizou-se agentes emolientes e silicones para facilitar a solubilização e/ou dispersão dos filtros químicos e físicos. A segunda etapa deste trabalho foi a avaliação da segurança do succinato de rutina, tendo como padrão a rutina, por meio do método alternativo de toxicidade in vitro, o XTT. Após o screening das concentrações ensaiadas, as que apresentaram menor nível de morte celular foram respectivamente, 0,1% ou 1 mg/mL (rutina) e 0,4% ou 4 mg/mL (succinato de rutina). Segundo os resultados do TEA, as formulações contendo succinato de rutina associada ou não aos filtros solares em ambas as bases cosméticas (A - Crodafos®CES + Uniox®C e B - Hostacerin®SAF) foram selecionadas para a continuidade do Teste de Estabilidade Normal (TEN). Neste teste, as emulsões fotoprotetoras foram avaliadas frente aos parâmetros: propriedades organolépticas (aspecto, cor e odor), aspectos físico-químicos (medição de pH e de viscosidade) e funcionais (atividade antirradicalar e eficácia fotoprotetora in vitro). Os resultados apresentados pela formulação MS (succinato de rutina associado aos filtros químicos e físico) foram: homogeneidade, a não modificação de cor e odor em temperatura ambiente, a não alterações significativas de valores de pH, de área de histerese, de atividade antirradicalar e de FPS. Esta estabilidade ocorreu principalmente quando incorporada à base cosmética A num período de 90 dias em 45ºC e 75% de umidade, 5ºC e 25ºC. Concluiu-se que a funcionalidade desta associação MS mostrou-se mais estável, mantendo a eficácia quanto à proteção solar e dentro de suas características reológicas poderia ser a mais bem aceita pelo consumidor.The current cosmetic market trend is to develop products containing vegetables raw materials. This work proposed to use the Technology of Green Chemical to increase the rutin stability in cosmetic formulas as regards of its antioxidant and photoprotective properties. The chemical synthesis was realized by the introduction of carboxylate groups on sugar moiety of rutin producing in rutin succinate. This derivative and/or rutin were incorporated into 74 test formulas. After the undergoing to preliminary and accelerated stabilities under different temperature and humidity conditions were selected 12 formulas (O/W emulsions). Emollient agents and silicones were used to improve the solubility and/or dispersion of the chemical and physical filters. The second stage of this work was to evaluate the safety of rutin succinate, rutin used as an internal standard, using the alternative method of in vitro toxicity, the XTT. After the screening of tested concentrations, the concentrations of the samples with the lowest level of cell death were 0.1% or 1 mg/mL (rutin) and 0.4% or 4 mg/mL (rutin succinate), respectively. According to results obtained in accelerated stability testing, the formulations containing rutin succinate in combination or not with UV filters in both O/W emulsions (A - Crodafos®CES + Uniox®C and B - Hostacerin®SAF) were selected for the long term stability test. In this test the sunscreens were evaluated in the following parameters: the organoleptic properties (appearance, color and odor), physico-chemical aspects (pH value and viscosity) and functional (antiradicalar activity and in vitro photoprotection efficacy). The results presented by the MS formula (rutin succinate associated with physical filter and chemical filters) were: uniformity, stability of color and odor at room temperature and showed no significant difference, as well stability in: pH and SPF (Sun Protection Factor) values, hysteresis area, antiradicalar activity. These results were observed mainly when it was incorporated to O/W emulsion A (90 days of analyses at 45°C and 75% humidity, 5°C and 25°C). It was observed the functionality of MS association was more stable, maintaining photoprotective efficacy and within their rheological properties could be more accepted by consumers.
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Moolman, Judith Margaretha. „Formulation, in vitro release and transdermal diffusion of azelaic acid with topical niacinamide / J.M. Moolman“. Thesis, North-West University, 2010. http://hdl.handle.net/10394/3987.
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Acne is a common skin disease that affects the follicular unit of the skin. Inflammatory- and noninflammatory forms of acne exist. The most affected areas on the body include the face, upper part of the chest and the back. These are the areas with the most sebaceous follicles. Acne occurs when hyperkeratinisation causes the cells of the hair follicle to shed too fast. These cells then block the follicle opening. Thus, sebum cannot pass through the hair follicle onto the skin.
The human skin is composed of three layers, namely the epidermis, which acts as a waterproof layer and a barrier to infections; the dermis, which contains the skin appendages; and the subcutaneous fat layer. Skin acts as a protective layer against pathogens and damage to the body. It also provides a semi-impermeable barrier to prevent water loss.
Azelaic acid and niacinamide are both currently used in the treatment of acne. Azelaic acid is a saturated dicarboxylic acid which is used to treat mild to moderate acne. It has antibacterial, keratolytic and comedolytic properties. Niacinamide, on the other hand, is the amide of nicotinic acid and is beneficial in the treatment of both papular and pustular acne. It has a demonstrated anti-inflammatory action and causes dose-dependent inhibition of sebocyte secretions.
The Pheroid™ delivery system is a colloidal system that consists of even lipid-based submicron-and micron-sized structures that are very unique in nature. This technology is able to improve the absorption and/or efficacy of various active ingredients, as well as other compounds.
In this study, a cream, Pheroid™ cream, a gel and a Pheroid™ gel were formulated, containing both azelaic acid and niacinamide. Stability tests were conducted on these formulations for six months, and it was established that none of the formulations were stable under the different storage conditions. Tests that were conducted during stability testing, as determined by the Medicines Control Council, included: assay, mass variation, appearance, viscosity, pH determination and confocal laser scanning microscopy (CLSM).
Diffusion studies (12 hours long in total) with vertical Franz cells were conducted with Caucasian female skin obtained after abdominoplastic surgery. Tape-stripping followed in order to establish the epidermis and dermis concentrations of azelaic acid and niacinamide. Significant concentrations of both active ingredients were found in the epidermis and the dermis after 12 hours.Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2010.
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Jiang, Hongcheng. „Fabrication and characterization of microporous calcium phosphate coatings and in vitro evaluation of chemical stability“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ63317.pdf.
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Li, Weiqi. „The endothelial glycocalyx : recovery, stability and role in electric field-directed cell migration in vitro“. Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8942.
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Cardiovascular disease is the leading cause of unnatural death worldwide. Damage to the endothelial glycocalyx impairs endothelial functions and thereafter leads to the development of cardiovascular diseases. Despite this, many issues remain to be explored in our understanding of the metabolism and vasculoprotective potential of the glycocalyx. This study focuses on the recovery and structural stability of the glycocalyx, and its role in electric field-directed cell migration in vitro. The integrity of the glycocalyx is compromised following trypsin treatment during cell passages. Results from our study show that cell seeding density affects the recovery speed of the glycocalyx in the first 48h. Higher cell density results in more rapid recovery of the glycocalyx. Regardless of the initial cell seeding density, a well-developed glycocalyx layer is observed when cell confluence is reached. Micropatterning is used to study effects of the cell shape on the recovery of the glycocalyx. Elliptical patterns have been used to conform endothelial cells to torpedo shapes, mimicking their morphology under a shear flow. More rapid development of the glycocalyx on elliptical cells is observed than that on circular shaped cells during the early stage of recovery. Effects of the actin cytoskeleton on the stability of the glycocalyx are investigated, following our interest in shedding of the glycocalyx in abnormal vascular microenvironment. Rapid depolymerisation of the actin cytoskeleton leads to cell retraction within 10mins, with the glycocalyx preserved on the cell surface. This is also seen during 24h persistent actin disruption under static conditions. However, when endothelial cells are subjected to 24h steady laminar shear stress, the glycocalyx is seen to shift to the downstream of the cell surface in the control group, and with actin depolymerisation, significant shedding of the glycocalyx from the luminal surface of the cell is observed. This happens together with the loss of focal adhesions on the basal membrane. Using a custom designed electric field (EF) chamber, I demonstrate that the cell migration speed increases by 30~40% following 5h of EF exposure. Cells also show preferred movement towards the anode. However, both are abolished after the enzymatic removal of the glycocalyx, indicating that the speedup and the directional cell migration in applied EF require the presence of the glycocalyx. Even distribution of the glycocalyx on the cell surface at the end of the EF stimulation suggests that EF-directed cell migration is not related to the polarization of the glycocalyx on the cell membrane. All these findings provide a better understanding of the glycocalyx, which will help to develop new strategies for protection of the glycocalyx, restoration of endothelial functions and finally prevention of cardiovascular diseases.
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Gupta, Antje. „In-vivo und In-vitro-Stabilität und Metabolismus von Gemischtligandkomplexen des 99m Tc“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2000. http://nbn-resolving.de/urn:nbn:de:swb:14-994673277281-08594.
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