Global ETD Search

111	Nano-émulsions radio-opaques iodées pour applications précliniques en imagerie par rayons X / Iodinated nana-emulsions for preclinical X-ray imaging applications Li, Xiang 07 November 2012 (has links) La micro-tomodensitométrie à rayons X (dite micro-CT, CT = Computed Tomography), est une technique d’imagerie de haute résolution qui consiste d’une part à mesurer l’absorption des rayons X par les tissus, et d’autre part de reconstruire les images et les structures anatomiques en 3 dimensions par traitement informatique. L’agent de contraste est une substance capable d’améliorer la visibilité des structures d’un organe ou d’un liquide organique in vivo. Ce travail de thèse a eu pour objectif le développement d’agents de contraste iodés sous formes de nano-émulsions pour des applications précliniques en imagerie biomédicale. Nous nous sommes proposés d’étudier d’une part des nano-émulsions iodées afin d’avoir une longue rémanence vasculaire in vivo, une meilleure biocompatibilité et d’autre part de mettre au point une synthèse et une formulation plus simples que celles des agents de contraste nanoparticulaires commercialisés. Trois différentes huiles iodées ont été synthétisées et utilisées comme partie contrastante dans les nano-émulsions. Enfin, les nano-émulsions de l’α-tocophérol iodé nous ont permis d’atteindre l’objectif de cette thèse. Ces nano-émulsions iodées ont montré une très bonne biocompatibilité et combinent à la fois les propriétés d’un agent de contraste à longue rémanence vasculaire et un agent de contraste spécifique du foie. / The X-ray microtomography (called mico-CT, CT = Computed Tomography) is a high-resolution X-ray tomography, uses X-rays to create cross-sections of a 3D-object that later can be used to recreate a virtual model without destroying the original model. The contrast agent is a substance used to enhance the contrast of structures or fluids within the body in medical imaging. The purposes of the thesis were the development of iodine-containing nano-emulsion based contrast for preclinical applications in biomedical imaging. We proposed to study blood pool contrast agents based on iodine-containing nano-emulsions and to develop simpler procedure for the preparation of these iodine-containing nano-emulsions. Three different iodinated oils were synthesized and used as the contrasting part in the nano-emulsions. Finally, nano-emulsions of iodinated α-tocopherol have been enabled us to achieve the purpose of the thesis. These iodinated nano-emulsions demonstrated very good biocompatibility and showed prolonged and significant contrast enhancement in both bloodstream and liver tissues. Agent de contraste iodé Nano-émulsion Mico-CT Imagerie par rayons X Imagerie préclinique Vectorisation passive Iodinated contrast agent Nano-emulsion Mico-CT X-ray imaging Preclinical imaging Passive targeting 547.7
112	Modeling cancer predisposition: Profiling Li-Fraumeni syndrome patient-derived cell lines using bioinformatics and three-dimensional culture models Phatak, Amruta Rajendra 07 October 2015 (has links) Indiana University-Purdue University Indianapolis (IUPUI) / Although rare, classification of over 200 hereditary cancer susceptibility syndromes accounting for ~5-10% of cancer incidence has enabled the discovery and understanding of cancer predisposition genes that are also frequently mutated in sporadic cancers. The need to prevent or delay invasive cancer can partly be addressed by characterization of cells derived from healthy individuals predisposed to cancer due to inherited "single-hits" in genes in order to develop patient-derived samples as preclinical models for mechanistic in vitro studies. Here, we present microarray-based transcriptome profiling of Li-Fraumeni syndrome (LFS) patient-derived unaffected breast epithelial cells and their phenotypic characterization as in vitro three-dimensional (3D) models to test pharmacological agents. In this study, the epithelial cells derived from the unaffected breast tissue of a LFS patient were cultured and progressed from non-neoplastic to a malignant stage by successive immortalization and transformation steps followed by growth in athymic mice. These cell lines exhibited distinct transcriptomic profiles and were readily distinguishable based upon their gene expression patterns, growth characteristics in monolayer and in vitro 3D cultures. Transcriptional changes in the epithelial-to-mesenchymal transition gene signature contributed to the unique phenotypes observed in 3D culture for each cell line of the progression series; the fully transformed LFS cells exhibited invasive processes in 3D culture with disorganized morphologies due to cell-cell miscommunication, as seen in breast cancer. Bioinformatics analysis of the deregulated genes and pathways showed inherent differences between these cell lines and targets for pharmacological agents. After treatment with small molecule APR-246 that restores normal function to mutant p53, we observed that the neoplastic LFS cells had reduced malignant invasive structure formation from 73% to 9%, as well as an observance of an increase in formation of well-organized structures in 3D culture (from 27% to 91%) by stereomicroscopy and confocal microscopy. Therefore, the use of well-characterized and physiologically relevant preclinical models in conjunction with transcriptomic profiling of high-risk patient derived samples as a renewable laboratory resource can potentially guide the development of safer and more effective chemopreventive approaches. Breast cancer progression Epithelial-to-mesenchymal transition Genomics Li-Fraumeni syndrome Preclinical in vitro models Three-dimensional culture Cancer -- Susceptibility Cancer -- Genetic aspects p53 protein p53 antioncogene Genetic transcription Cancer -- Molecular diagnosis
113	Implementation of New Algorithms for an Accurate Gamma-Ray Impact Determination in Scintillation Monolithic Blocks for PET Applications Freire López-Fando, Marta 07 September 2023 (has links) Tesis por compendio / [ES] La Tomografía por Emisión de Positrones (PET) es una potente técnica de imagen que proporciona mediante el uso de radiofármacos específicos medidas cuantitativas de los procesos biológicos y fisiológicos que tienen lugar en el organismo a nivel molecular. Las imágenes PET proporcionan información funcional que permite el diagnóstico precoz y el seguimiento personalizado del tratamiento terapéutico. La PET tiene aplicaciones en diversas áreas clínicas y de investigación, como la oncología, la neurología o la cardiología, entre otras. Los esfuerzos por mejorar las prestaciones de los sistemas PET se centran en aumentar su sensibilidad y calidad de imagen, lo que permite una evaluación clínica más precisa. En las imágenes PET, se inyecta al paciente un radiotrazador marcado con un radionúclido emisor de positrones que se distribuye por todo el cuerpo. Durante la desintegración radiactiva del trazador, el isótopo emite un positrón que se aniquila con un electrón del tejido circundante, generando dos rayos gamma de 511 keV emitidos a aproximadamente 180º. La técnica PET se basa por tanto en la detección simultánea de estos dos rayos gamma, denominados fotones de aniquilación, empleando habitualmente un anillo de detectores alrededor del paciente. Mejorando el diseño y el rendimiento de estos detectores, se mejoran las capacidades diagnósticas que ofrece la imagen PET. Para aumentar el rendimiento, se ha sugerido utilizar detectores basados en diseños de cristales monolíticos, debido a sus ventajas en comparación con los detectores pixelados. Sin embargo, su implementación en escáneres comerciales requiere superar algunos retos relacionados principalmente con los métodos de posicionamiento y los procedimientos de calibración necesarios para proporcionar las coordenadas de impacto del fotón de aniquilación y el tiempo de llegada de los fotones. Esta tesis doctoral se centra en el desarrollo y validación experimental de metodologías para la determinación precisa de esta información en detectores monolíticos, haciendo hincapié en su aplicación práctica también a sistemas PET completos. Durante esta tesis se han estudiado los principios fundamentales de los detectores PET monolíticos para comprender su comportamiento y limitaciones. En primer lugar, se han considerado las configuraciones típicas de detectores monolíticos basadas en bloques de centelleo continuo acoplados a matrices de SiPMs planas; además, también se han evaluado y validado otros enfoques novedosos. Se han desarrollado dos metodologías principales, una basada en técnicas analíticas y otra en algoritmos de Aprendizaje Profundo, para el posicionamiento 3D de la interacción del fotón con el fin de aumentar el rendimiento global del detector. Finalmente, los métodos propuestos han sido validados a nivel de detector, pero también en diferentes escáneres PET desarrollados en i3M. La presente tesis se basa en un compendio de los artículos más relevantes publicados en revistas revisadas por pares por el doctorando y está organizada de la siguiente manera. El Capítulo I presenta una introducción al trabajo de la tesis, compuesto por tres secciones: Imagen Médica, principios de la Tomografía por Emisión de Positrones y, Estimación de posición y calibración en detectores monolíticos. El Capítulo II contiene los objetivos específicos de esta tesis y las principales contribuciones del candidato a este campo. Este capítulo también incluye algunas metodologías y resultados recientes que aún no han sido publicados. El Capítulo III colecciona una copia de los cuatro artículos publicados seleccionados para el compendio, en los que el candidato es el primer autor [1]-[4]. En el Capítulo IV se discuten los principales resultados y conclusiones alcanzados durante la tesis. Por último, el Capítulo V presenta la discusión de esta tesis, resumiendo las principales contribuciones y destacando los logros científicos. / [CAT] La Tomografia per Emissió de Positrons (PET) és una potent tècnica d'imatge que proporciona mitjançant l'ús de radiofàrmacs específics mesures quantitatives dels processos biològics i fisiològics que tenen lloc en l'organisme a nivell molecular. Les imatges PET proporcionen informació funcional que permet el diagnòstic precoç i el seguiment personalitzat del tractament terapèutic. La PET té aplicacions en diverses àrees cliniques y d¿investigació, com l'oncologia, la neurologia o la cardiologia, entre altres. Els esforços per millorar les prestacions dels sistemes PET se centren en millorar la seua sensibilitat i qualitat d'imatge, la qual cosa permet una avaluació clínica més precisa més precís. En les imatges PET, s'injecta al pacient un radiotraçador marcat amb un radionúclid emissor de positrons que es distribueix per tot el cos. Durant la desintegració radioactiva del traçador, l'isòtop emet un positró que s'aniquila amb un electró del teixit circumdant, generant dos raigs gamma de 511 keV emesos a aproximadament 180º. La tècnica PET es basa per tant en la detecció simultània d'aquests dos raigs gamma, denominats fotons d'anihilació, emprant habitualment un anell de detectors al voltant del pacient. Millorant el disseny i el rendiment d'aquests detectors, es millora les capacitats diagnòstiques que ofereix la imatge PET. Per a augmentar el rendiment, s'ha suggerit utilitzar detectors basats en dissenys de cristalls monolítics, a causa dels seus avantatges en comparació amb els detectors pixelats. No obstant això, la seua implementació en escàners comercials requereix superar alguns reptes relacionats principalment amb els mètodes de posicionament i els procediments de calibració necessaris per a proporcionar les coordenades d'impacte del fotó d'anihilació i el temps d'arribada dels fotons. Aquesta tesi doctoral se centra en el desenvolupament i validació experimental de metodologies per a la determinació precisa d'aquesta informació en detectors monolítics, posant l'accent en la seua aplicació pràctica també a sistemes PET complets. Durant aquesta tesi s'han estudiat els principis fonamentals dels detectors PET monolítics per a comprendre el seu comportament i limitacions. En primer lloc, s'han considerat les configuracions típiques de detectors monolítics basats en blocs de centellege continu acoblats a matrius SiPM planes; a més, també s'han evaluat i validat altres enfocaments nous. S'han desenvolupat dues metodologies principals, una basada en tècniques analítiques i una altra en algoritmes d'Aprenentatge Profund, pel posicionament 3D de la interacció del fotó amb la finalitat d'augmentar el rendiment global del detector. Finalment, els mètodes proposats han sigut validats a nivell de detector però també en diferents escàners PET desenvolupats en i3M. La present tesi es basa en un compendi dels articles més rellevants publicats en revistes revisades per parells pel doctorand i està organitzada de la següent manera. El Capítol I presenta una introducció al treball de tesi, compost per tres seccions: Imatge Mèdica, principis de la Tomografia per Emissió de Positrons i, Estimació de posició i calibració en detectors monolítics. El Capítol II conté els objectius específics d'aquesta tesi i les principals contribucions del candidat a aquest camp. Aquest capítol també inclou algunes metodologies i resultats recents que encara no han sigut publicats. El Capítol III col·lecciona una còpia dels quatre articles publicats seleccionats pel compendi, en els quals el candidat és el primer autor [1]-[4]. En el Capítol IV es discuteixen els principals resultats i conclusions aconseguits durant la tesi. Finalment, el Capítol V presenta la discussió d'aquesta tesi, resumint les principals contribucions i destacant els assoliments científics. / [EN] Positron Emission Tomography (PET) is a powerful imaging technique that provides quantitative measurements of biological and physiological processes occurring within the body at the molecular level by using specific radiopharmaceuticals. PET imaging returns functional information that allows for early diagnosis and personalized therapy treatment follow up. It has applications in several research and clinical areas, such as oncology, neurology or cardiology, among others. Efforts to improve PET systems performance are focused on increasing their sensitivity and image quality, allowing for more accurate clinical assessments. In PET imaging, a radiotracer labeled with a positron-emitting radionuclide is injected to the patient and consequently, distributed throughout the body. During the radiotracer decay, the isotope emits a positron that annihilates with an electron of the surrounding tissues, generating two 511 keV gamma-rays emitted at approximately 180º. The PET technique is based therefore on the simultaneous detection of these two gamma-rays, called annihilation photons, by usually employing a ring of detectors around the patient. Improving the design and performance of these detectors, increases the diagnostic capabilities of PET imaging. To boost PET performance, it has been suggested to use detectors based on monolithic crystals designs, due to their advantages compared to pixelated detectors. However, their implementation in commercial scanners requires overcoming some challenges mostly related to photon impact positioning methods and calibration procedures to provide the impact coordinates and time of arrival of the annihilation photons. This PhD thesis focuses on the development and experimental validation of methodologies for an accurate determination of this information in monolithic detectors, emphasizing in their practical application to full PET systems. During this thesis, the main principles of monolithic-based PET detectors have been studied to understand their behavior and limitations. Typical monolithic detector configurations based on continuous scintillation blocks coupled to flat SiPM arrays have been first considered; additionally, other novel approaches have been also validated. Two main methodologies for 3D photon interaction positioning, one based on analytical methods and another based on Deep Learning algorithms, have been developed to increase the overall detector performance. The proposed methods have been validated at the detector level but also in different PET scanners developed by our group. The present thesis is based on a compendium of the most relevant papers published in peer-reviewed journals by the PhD candidate and is organized as follows. Chapter I presents an introduction to the thesis work, composed by three sections: Medical Imaging, principles of Positron Emission Tomography and, Position estimation and calibration in monolithic-based detectors. Chapter II contains the specific objectives of this thesis and the main contributions of the candidate to the field. This chapter also includes some recent methodologies and results that have not yet been published. Chapter III collects an author copy of the four published articles selected for the compendium, in which the candidate is the first author [1]-[4]. In Chapter IV the main results and conclusion achieved during the thesis are discussed. Finally, Chapter V presents the discussion of this thesis, summarizing the main contributions and highlighting the scientific achievements. / Freire López-Fando, M. (2023). Implementation of New Algorithms for an Accurate Gamma-Ray Impact Determination in Scintillation Monolithic Blocks for PET Applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196084 / Compendio Cristales monolíticos Neural networks Preclinical imaging Molecular imaging Imagen molecular Imagen médica Imagen preclínica Medical Imaging Gamma-ray detectors Scintillator Positron Emission Tomography (PET) Monolithic crystals
114	<b>Reprogramming the Pancreatic Cancer Stroma by Targeting Coagulation at the Tumor Microenvironment</b> Sae Rome Choi (18392505) 17 April 2024 (has links) <p dir="ltr">Pancreatic ductal adenocarcinoma (PDAC) remains one of the most deadliest cancer and despite advancements in cancer therapy, remain highly refractory to treatment, largely due to its desmoplastic tumor microenvironment (TME) characterized by complex interactions among cancer cells and stromal components. Particularly, the PDAC associated coagulation system due to leaky tumor vasculatures plays a pivotal role in reshaping the PDAC stroma and its pathogenesis. Understanding the intricate interplay between tumor cells, stromal cells, and the elevated coagulation pathway elements, including tissue factor, thrombin, and fibrin, is essential for developing effective therapeutic strategies. To address these challenges, this research proposes the engineering of a novel PDAC-associated coagulation system using a microfluidic technology, known as coagulation-on-tumor-microenvironment-on-chip (cT-MOC). The study aims to integrate key coagulation pathways in cT-MOC to investigate pivotal interactions in the PDAC stroma: <i>i)</i> thrombin-protease-activated receptors (PARs) mediated promotion of PDAC fibrosis via activation of cancer-fibroblast cross-talk; <i>ii)</i> in-depth analysis of transport and mechanical properties of collagen-fibrin microstructure; <i>iii)</i> inhibited drug delivery in reprogrammed PDAC stroma due to pronounced fibrin deposition on collagen. By leveraging innovative microfluidic technologies and comprehensive experimental approaches, the research endeavors to provide a novel platform that bridges traditional <i>in vitro</i> and <i>in vivo</i> models to overcome the challenges posed by the desmoplastic TME and enhance therapeutic strategies for treatment by targeting the coagulation at the PDAC TME.</p> Cancer cell biology Cancer diagnosis Chemotherapy Solid tumours Biofabrication Biomaterials Biomechanical engineering Tissue engineering pancreatic adenocarcinoma cancer ce... lab on-a-chip device preclinical cancer models Tissue engineered cell culture models drug delivery & targeting
115	Validation des modèles de pharmacologie de sécurité et évaluation de la valeur thérapeutique de l'oxytocine dans le traitement de l'infarctus du myocarde Authier, Simon 06 1900 (has links) En février, 2009 un rapport de PHRMA (Pharmaceutical Research and Manufacturers of America) confirmait que plus de 300 médicaments pour le traitement des maladies cardiaques étaient en phase d’essais cliniques ou en révision par les agences règlementaires. Malgré cette abondance de nouvelles thérapies cardiovasculaires, le nombre de nouveaux médicaments approuvés chaque année (toutes indications confondues) est en déclin avec seulement 17 et 24 nouveaux médicaments approuvés en 2007 et 2008, respectivement. Seulement 1 médicament sur 5000 sera approuvé après 10 à 15 ans de développement au coût moyen de 800 millions $. De nombreuses initiatives ont été lancées par les agences règlementaires afin d’augmenter le taux de succès lors du développement des nouveaux médicaments mais les résultats tardent. Cette stagnation est attribuée au manque d’efficacité du nouveau médicament dans bien des cas mais les évaluations d’innocuité remportent la palme des causes d’arrêt de développement. Primum non nocere, la maxime d’Hippocrate, père de la médecine, demeure d’actualité en développement préclinique et clinique des médicaments. Environ 3% des médicaments approuvés au cours des 20 dernières années ont, par la suite, été retirés du marché suite à l’identification d’effets adverses. Les effets adverses cardiovasculaires représentent la plus fréquente cause d’arrêt de développement ou de retrait de médicament (27%) suivi par les effets sur le système nerveux. Après avoir défini le contexte des évaluations de pharmacologie de sécurité et l’utilisation des bio-marqueurs, nous avons validé des modèles d’évaluation de l’innocuité des nouveaux médicaments sur les systèmes cardiovasculaires, respiratoires et nerveux. Évoluant parmi les contraintes et les défis des programmes de développements des médicaments, nous avons évalué l’efficacité et l’innocuité de l’oxytocine (OT), un peptide endogène à des fins thérapeutiques. L’OT, une hormone historiquement associée à la reproduction, a démontré la capacité d’induire la différentiation in vitro de lignées cellulaires (P19) mais aussi de cellules souches embryonnaires en cardiomyocytes battants. Ces observations nous ont amené à considérer l’utilisation de l’OT dans le traitement de l’infarctus du myocarde. Afin d’arriver à cet objectif ultime, nous avons d’abord évalué la pharmacocinétique de l’OT dans un modèle de rat anesthésié. Ces études ont mis en évidence des caractéristiques uniques de l’OT dont une courte demi-vie et un profil pharmacocinétique non-linéaire en relation avec la dose administrée. Ensuite, nous avons évalué les effets cardiovasculaires de l’OT sur des animaux sains de différentes espèces. En recherche préclinique, l’utilisation de plusieurs espèces ainsi que de différents états (conscients et anesthésiés) est reconnue comme étant une des meilleures approches afin d’accroître la valeur prédictive des résultats obtenus chez les animaux à la réponse chez l’humain. Des modèles de rats anesthésiés et éveillés, de chiens anesthésiés et éveillés et de singes éveillés avec suivi cardiovasculaire par télémétrie ont été utilisés. L’OT s’est avéré être un agent ayant d’importants effets hémodynamiques présentant une réponse variable selon l’état (anesthésié ou éveillé), la dose, le mode d’administration (bolus ou infusion) et l’espèce utilisée. Ces études nous ont permis d’établir les doses et régimes de traitement n’ayant pas d’effets cardiovasculaires adverses et pouvant être utilisées dans le cadre des études d’efficacité subséquentes. Un modèle porcin d’infarctus du myocarde avec reperfusion a été utilisé afin d’évaluer les effets de l’OT dans le traitement de l’infarctus du myocarde. Dans le cadre d’un projet pilote, l’infusion continue d’OT initiée immédiatement au moment de la reperfusion coronarienne a induit des effets cardiovasculaires adverses chez tous les animaux traités incluant une réduction de la fraction de raccourcissement ventriculaire gauche et une aggravation de la cardiomyopathie dilatée suite à l’infarctus. Considérant ces observations, l’approche thérapeutique fût révisée afin d’éviter le traitement pendant la période d’inflammation aigüe considérée maximale autour du 3ième jour suite à l’ischémie. Lorsqu’initié 8 jours après l’ischémie myocardique, l’infusion d’OT a engendré des effets adverses chez les animaux ayant des niveaux endogènes d’OT élevés. Par ailleurs, aucun effet adverse (amélioration non-significative) ne fût observé chez les animaux ayant un faible niveau endogène d’OT. Chez les animaux du groupe placebo, une tendance à observer une meilleure récupération chez ceux ayant des niveaux endogènes initiaux élevés fût notée. Bien que la taille de la zone ischémique à risque soit comparable à celle rencontrée chez les patients atteints d’infarctus, l’utilisation d’animaux juvéniles et l’absence de maladies coronariennes sont des limitations importantes du modèle porcin utilisé. Le potentiel de l’OT pour le traitement de l’infarctus du myocarde demeure mais nos résultats suggèrent qu’une administration systémique à titre de thérapie de remplacement de l’OT devrait être considérée en fonction du niveau endogène. De plus amples évaluations de la sécurité du traitement avec l’OT dans des modèles animaux d’infarctus du myocarde seront nécessaires avant de considérer l’utilisation d’OT dans une population de patients atteint d’un infarctus du myocarde. En contre partie, les niveaux endogènes d’OT pourraient posséder une valeur pronostique et des études cliniques à cet égard pourraient être d’intérêt. / In february 2009, a report from PHRMA (Pharmaceutical Research and Manufacturers of America) confirmed that more than 300 drugs for treatment of cardiovascular diseases were in clinical trials or under review by regulatory agencies. Despite the abundance of new cardiovascular therapies, the number of new drugs approved each year (all indications combined) is declining steadily with only 17 and 24 new drugs approved in 2007 and 2008, respectively. Only 1 drug out of 5000 candidates will be approved after 10 to 15 years of development with an average cost of $800 millions. Several initiatives have been launched by regulatory agencies to increase the success rate in drug development but results are still awaited. This stagnation is attributed to the lack of efficacy of several drug candidates but safety assessments are the leading cause of drug development discontinuation. Primum non nocere, the maxim from Hippocrate, father of medicine, remains of major relevance in preclinical and clinical drug development. Over the past 20 years, approximately 3% of approved drugs were subsequently withdrawn from the market due to adverse effects. Cardiovascular adverse effects represent the most frequent cause of drug development discontinuation or withdrawal (27%) followed by effects on the nervous system. After defining the context of safety pharmacology evaluations and the use of biomarkers in drug development, we validated safety pharmacology models to investigate drug-induced cardiovascular, respiratory and neurological effects. As we progressed within constraints and challenges of drug development, we evaluated the efficacy and safety of oxytocin, an endogenous peptide with therapeutic potential. Oxytocin (OT), a hormone historically associated with reproduction, demonstrated the ability to induce in vitro differentiation of cell lines (P19) but also embryonic stem cells into beating cardiomyocytes. These observations lead us to consider the use of OT as a treatment for myocardial infarct. To achieve this ultimate goal, we first evaluated the pharmacokinetic of OT in an anesthetized rat model. These investigations highlighted the unique characteristics of OT including a very short half-life and a non-linear pharmacokinetic profile in response to the dose. Cardiovascular effects of OT in healthy animals were then evaluated in various species. In preclinical research, the use of various animal species and state of consciousness (conscious or anesthetized) is recognized as one of the best strategies to increase the predictive value of results obtained in animals to the human response. Our initial investigations of OT treatment regimens used various animal models including conscious and anesthetized rats, anesthetized pigs, conscious dogs with indirect blood pressure monitoring and diuresis and conscious monkeys with cardiovascular telemetry monitoring. These studies confirmed OT to have significant hemodynamic effects with variable responses depending on the state of consciousness (conscious or anesthetized), the dose, the administration protocol (bolus or infusion) and the species that were used. These screening studies enabled selection of a treatment regimen and dose without adverse effects that could subsequently be tested in efficacy studies. A porcine myocardial infarct (MI) model with reperfusion was used to evaluate the effects of OT following myocardial ischemia. In a pilot project, continuous infusion of OT initiated immediately at coronary reperfusion induced cardiovascular adverse effects in all treated animals including a reduction of left ventricular fraction shortening and worsening of dilated cardiomyopathy which is typical following MI. Considering these observations, the therapeutic strategy was revised to avoid OT treatment during the inflammatory phase which was considered maximal around day 3 post-ischemia. When initiated 8 days after MI, OT infusion induced adverse effects in animals with elevated endogenous levels of OT. In contrast, no significant effects (not statistically significant improvement) were observed in animals with low endogenous OT baseline. In placebo treated animals, a trend to observe a better recovery was noted in animals with high endogenous OT baseline. While the size of the ischemic zone was comparable to human patients with MI, the use of juvenile animals and the absence of coronary disease are important limitations of the porcine model. The potential of OT for treatment of MI remains but our results suggest that systemic administration of OT by continuous infusion as part of a replacement therapy should be investigated further in relation to endogenous levels. Further investigations on safety of the treatment with OT on animal MI models are warranted before the use of OT can be considered in the patient population after myocardial infarct. On the other hand, endogenous levels of OT may have a prognostic value and clinical trials to investigate this hypothesis may be of interest. Oxytocine Pharmacologie de Sécurité Effets Cardiovasculaires Adverses Pharmacologie Physiologie Toxicologie Étude préclinique Infarctus du Myocarde Fraction d’Éjection Planimétrie Porc Utilisation Thérapeutique Infusion Continue Pharmacocinétique Oxytocin Safety Pharmacology Cardiovascular effects Pharmacology Physiology Toxicology Preclinical study Myocardial infarct Ejection fraction Planimetry Pig Therapeutic use Continuous infusion Pharmacokinetic
116	Validation des modèles de pharmacologie de sécurité et évaluation de la valeur thérapeutique de l'oxytocine dans le traitement de l'infarctus du myocarde Authier, Simon 06 1900 (has links) En février, 2009 un rapport de PHRMA (Pharmaceutical Research and Manufacturers of America) confirmait que plus de 300 médicaments pour le traitement des maladies cardiaques étaient en phase d’essais cliniques ou en révision par les agences règlementaires. Malgré cette abondance de nouvelles thérapies cardiovasculaires, le nombre de nouveaux médicaments approuvés chaque année (toutes indications confondues) est en déclin avec seulement 17 et 24 nouveaux médicaments approuvés en 2007 et 2008, respectivement. Seulement 1 médicament sur 5000 sera approuvé après 10 à 15 ans de développement au coût moyen de 800 millions $. De nombreuses initiatives ont été lancées par les agences règlementaires afin d’augmenter le taux de succès lors du développement des nouveaux médicaments mais les résultats tardent. Cette stagnation est attribuée au manque d’efficacité du nouveau médicament dans bien des cas mais les évaluations d’innocuité remportent la palme des causes d’arrêt de développement. Primum non nocere, la maxime d’Hippocrate, père de la médecine, demeure d’actualité en développement préclinique et clinique des médicaments. Environ 3% des médicaments approuvés au cours des 20 dernières années ont, par la suite, été retirés du marché suite à l’identification d’effets adverses. Les effets adverses cardiovasculaires représentent la plus fréquente cause d’arrêt de développement ou de retrait de médicament (27%) suivi par les effets sur le système nerveux. Après avoir défini le contexte des évaluations de pharmacologie de sécurité et l’utilisation des bio-marqueurs, nous avons validé des modèles d’évaluation de l’innocuité des nouveaux médicaments sur les systèmes cardiovasculaires, respiratoires et nerveux. Évoluant parmi les contraintes et les défis des programmes de développements des médicaments, nous avons évalué l’efficacité et l’innocuité de l’oxytocine (OT), un peptide endogène à des fins thérapeutiques. L’OT, une hormone historiquement associée à la reproduction, a démontré la capacité d’induire la différentiation in vitro de lignées cellulaires (P19) mais aussi de cellules souches embryonnaires en cardiomyocytes battants. Ces observations nous ont amené à considérer l’utilisation de l’OT dans le traitement de l’infarctus du myocarde. Afin d’arriver à cet objectif ultime, nous avons d’abord évalué la pharmacocinétique de l’OT dans un modèle de rat anesthésié. Ces études ont mis en évidence des caractéristiques uniques de l’OT dont une courte demi-vie et un profil pharmacocinétique non-linéaire en relation avec la dose administrée. Ensuite, nous avons évalué les effets cardiovasculaires de l’OT sur des animaux sains de différentes espèces. En recherche préclinique, l’utilisation de plusieurs espèces ainsi que de différents états (conscients et anesthésiés) est reconnue comme étant une des meilleures approches afin d’accroître la valeur prédictive des résultats obtenus chez les animaux à la réponse chez l’humain. Des modèles de rats anesthésiés et éveillés, de chiens anesthésiés et éveillés et de singes éveillés avec suivi cardiovasculaire par télémétrie ont été utilisés. L’OT s’est avéré être un agent ayant d’importants effets hémodynamiques présentant une réponse variable selon l’état (anesthésié ou éveillé), la dose, le mode d’administration (bolus ou infusion) et l’espèce utilisée. Ces études nous ont permis d’établir les doses et régimes de traitement n’ayant pas d’effets cardiovasculaires adverses et pouvant être utilisées dans le cadre des études d’efficacité subséquentes. Un modèle porcin d’infarctus du myocarde avec reperfusion a été utilisé afin d’évaluer les effets de l’OT dans le traitement de l’infarctus du myocarde. Dans le cadre d’un projet pilote, l’infusion continue d’OT initiée immédiatement au moment de la reperfusion coronarienne a induit des effets cardiovasculaires adverses chez tous les animaux traités incluant une réduction de la fraction de raccourcissement ventriculaire gauche et une aggravation de la cardiomyopathie dilatée suite à l’infarctus. Considérant ces observations, l’approche thérapeutique fût révisée afin d’éviter le traitement pendant la période d’inflammation aigüe considérée maximale autour du 3ième jour suite à l’ischémie. Lorsqu’initié 8 jours après l’ischémie myocardique, l’infusion d’OT a engendré des effets adverses chez les animaux ayant des niveaux endogènes d’OT élevés. Par ailleurs, aucun effet adverse (amélioration non-significative) ne fût observé chez les animaux ayant un faible niveau endogène d’OT. Chez les animaux du groupe placebo, une tendance à observer une meilleure récupération chez ceux ayant des niveaux endogènes initiaux élevés fût notée. Bien que la taille de la zone ischémique à risque soit comparable à celle rencontrée chez les patients atteints d’infarctus, l’utilisation d’animaux juvéniles et l’absence de maladies coronariennes sont des limitations importantes du modèle porcin utilisé. Le potentiel de l’OT pour le traitement de l’infarctus du myocarde demeure mais nos résultats suggèrent qu’une administration systémique à titre de thérapie de remplacement de l’OT devrait être considérée en fonction du niveau endogène. De plus amples évaluations de la sécurité du traitement avec l’OT dans des modèles animaux d’infarctus du myocarde seront nécessaires avant de considérer l’utilisation d’OT dans une population de patients atteint d’un infarctus du myocarde. En contre partie, les niveaux endogènes d’OT pourraient posséder une valeur pronostique et des études cliniques à cet égard pourraient être d’intérêt. / In february 2009, a report from PHRMA (Pharmaceutical Research and Manufacturers of America) confirmed that more than 300 drugs for treatment of cardiovascular diseases were in clinical trials or under review by regulatory agencies. Despite the abundance of new cardiovascular therapies, the number of new drugs approved each year (all indications combined) is declining steadily with only 17 and 24 new drugs approved in 2007 and 2008, respectively. Only 1 drug out of 5000 candidates will be approved after 10 to 15 years of development with an average cost of $800 millions. Several initiatives have been launched by regulatory agencies to increase the success rate in drug development but results are still awaited. This stagnation is attributed to the lack of efficacy of several drug candidates but safety assessments are the leading cause of drug development discontinuation. Primum non nocere, the maxim from Hippocrate, father of medicine, remains of major relevance in preclinical and clinical drug development. Over the past 20 years, approximately 3% of approved drugs were subsequently withdrawn from the market due to adverse effects. Cardiovascular adverse effects represent the most frequent cause of drug development discontinuation or withdrawal (27%) followed by effects on the nervous system. After defining the context of safety pharmacology evaluations and the use of biomarkers in drug development, we validated safety pharmacology models to investigate drug-induced cardiovascular, respiratory and neurological effects. As we progressed within constraints and challenges of drug development, we evaluated the efficacy and safety of oxytocin, an endogenous peptide with therapeutic potential. Oxytocin (OT), a hormone historically associated with reproduction, demonstrated the ability to induce in vitro differentiation of cell lines (P19) but also embryonic stem cells into beating cardiomyocytes. These observations lead us to consider the use of OT as a treatment for myocardial infarct. To achieve this ultimate goal, we first evaluated the pharmacokinetic of OT in an anesthetized rat model. These investigations highlighted the unique characteristics of OT including a very short half-life and a non-linear pharmacokinetic profile in response to the dose. Cardiovascular effects of OT in healthy animals were then evaluated in various species. In preclinical research, the use of various animal species and state of consciousness (conscious or anesthetized) is recognized as one of the best strategies to increase the predictive value of results obtained in animals to the human response. Our initial investigations of OT treatment regimens used various animal models including conscious and anesthetized rats, anesthetized pigs, conscious dogs with indirect blood pressure monitoring and diuresis and conscious monkeys with cardiovascular telemetry monitoring. These studies confirmed OT to have significant hemodynamic effects with variable responses depending on the state of consciousness (conscious or anesthetized), the dose, the administration protocol (bolus or infusion) and the species that were used. These screening studies enabled selection of a treatment regimen and dose without adverse effects that could subsequently be tested in efficacy studies. A porcine myocardial infarct (MI) model with reperfusion was used to evaluate the effects of OT following myocardial ischemia. In a pilot project, continuous infusion of OT initiated immediately at coronary reperfusion induced cardiovascular adverse effects in all treated animals including a reduction of left ventricular fraction shortening and worsening of dilated cardiomyopathy which is typical following MI. Considering these observations, the therapeutic strategy was revised to avoid OT treatment during the inflammatory phase which was considered maximal around day 3 post-ischemia. When initiated 8 days after MI, OT infusion induced adverse effects in animals with elevated endogenous levels of OT. In contrast, no significant effects (not statistically significant improvement) were observed in animals with low endogenous OT baseline. In placebo treated animals, a trend to observe a better recovery was noted in animals with high endogenous OT baseline. While the size of the ischemic zone was comparable to human patients with MI, the use of juvenile animals and the absence of coronary disease are important limitations of the porcine model. The potential of OT for treatment of MI remains but our results suggest that systemic administration of OT by continuous infusion as part of a replacement therapy should be investigated further in relation to endogenous levels. Further investigations on safety of the treatment with OT on animal MI models are warranted before the use of OT can be considered in the patient population after myocardial infarct. On the other hand, endogenous levels of OT may have a prognostic value and clinical trials to investigate this hypothesis may be of interest. Oxytocine Pharmacologie de Sécurité Effets Cardiovasculaires Adverses Pharmacologie Physiologie Toxicologie Étude préclinique Infarctus du Myocarde Fraction d’Éjection Planimétrie Porc Utilisation Thérapeutique Infusion Continue Pharmacocinétique Oxytocin Safety Pharmacology Cardiovascular effects Pharmacology Physiology Toxicology Preclinical study Myocardial infarct Ejection fraction Planimetry Pig Therapeutic use Continuous infusion Pharmacokinetic
117	Third Place Winner of the Conrad Jobst Award in the Gold Medal Paper Competition. Prevention of Spinal Cord Dysfunction in a New Model of Spinal Cord Ischemia Lopez, S, Manahan, E, Evans, J. R., Kao, R. L., Browder, W. 01 January 1995 (has links) Paraplegia or paraparesis caused by temporary cross-clamping of the aorta is a devastating sequela in patients after surgery of the thoracoabdominal aorta. No effective clinical method is available to protect the spinal cord from ischemic reperfusion injury. A small animal (rat) model of spinal cord ischemia is established to better understand the pathophysiological events and to evaluate potential treatments. Eighty-one male Sprague-Dawley rats weighing 300 g to 350 g were used for model development (45) and treatment evaluation (36). The heparinized and anesthetized rat was supported by a respirator following tracheostomy. The thoracic aorta was cannulated via the left carotid artery for post-clamping intra-aortic treatment solution administration. After thoracotomy, the aorta was freed and temporarily clamped just distal to the left subclavian artery and just proximal to the diaphragm for different time intervals: 0, 5, 10, 15, 20, 25, 30, 35, and 40 minutes (five animals per group). The motor function of the lower extremities postoperatively showed consistent impairment after 30 minutes clamping (5/5 rats were paralyzed), and this time interval was used for treatment evaluation. For each treatment, six animals per group were used, and direct local intra-aortic infusion of physiologic solution (2 mL) at different temperatures with or without buffer substances was given immediately after double cross-clamp to protect the ischemic spinal cord. Arterial blood (2 mL) was infused in the control group. The data indicate that the addition of HCO3-(20 mM) to the hypothermic (15 degrees C) solution offered complete protection of the spinal cord from ischemic injury.(ABSTRACT TRUNCATED AT 250 WORDS) acetates (therapeutic use) aorta (surgery) cardioplegic solutions (therapeutic use) disease models animal drug evaluation preclinical gluconates (therapeutic use) hepes (therapeutic use) hypothermia induced (methods) magnesium chloride (therapeutic use) male paraplegia (diagnosis etiology physiopathology prevention & control) postoperative complications (diagnosis etiology physiopathology prevention & control) potassium chloride (therapeutic use) rats sprague-dawley reperfusion (methods) reperfusion injury (diagnosis etiology physiopathology prevention & control) reproducibility of results sodium acetate sodium bicarbonate (therapeutic use) sodium chloride (therapeutic use) spinal cord (blood supply) time factors Surgery
118	Development of Sensitive In Vitro Assays to Assess the Ocular Toxicity Potential of Chemicals and Ophthalmic Products McCanna, David January 2009 (has links) The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes. The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations. in vitro Alternative Methods alamarBlue rhodamine tight junctions bovine lens viability toxicity mitochondria mitochondria integrity benzalkonium chloride sodium dodecyl sulphate sodium lauryl sulfate scanning electron microscopy Draize Draize maximal average scores zonula occludens cosmetic directive PETA humane society animal league ICCVAM ECVAM JaCVAM BCOP bovine cornea ocular irritants ocular irritation ocular toxicity human corneal epithelial cells vitro confocal confocal microscopy metabolic activity optical quality reactive oxygen species contact lens contact lens care solutions barrier function microbial keratitis mulitipurpose solutions tight junction cell damage claudin ZO-1 occludin MDCK Madin Madin-Darby canine kidney cells cornea human cornea human corneal epithelium epithelial cell line human corneal epithelial cell line sodium fluorescein sodium fluorescein permeability fluorescein permeability ocular surface cell monolayer Araki-Sasaki cell physiology risk assessment safety assessment ScanTox scanning laser lens epithelium corneal cells in vitro model ophthalmic formulations multiple instillation back vertex animal testing rabbit testing alternatives to animal testing cultured bovine lens toxicity of chemicals irritation irritants laser scanner organ culture delayed toxicity toxins hydrogen peroxide cornea toxicity cornea toxicity models prediction of human toxicity no observable adverse effect level lowest observable adverse effect level NOAEL LOAEL toxicity thresholds safety factors cornea uncertainty factors preservatives disinfectants ophthalmic products preclinical preclinical testing epithelial barrier drug penetration clinical confocal microscopy animal rights rabbit cornea human cornea human clinical effects toxic animal rights activist sensitive measures toxic effect toxicity threshold agar overlay agar diffusion agar overlay method agar diffusion method cytochrome cytochrome c apoptosis necrotic apoptotic necrosis caspase rhodamine 123 resazuran resorufin cell death cell viability metabolic dye microsomal microsomal enzymes cytotoxicity cytotoxic cytotoxic effect MTT XTT WST-1 plasma membrane mitochondrial mitochondrial morphology ocular toxicity potential ocular toxicity human corneal epithelial cell line confocal analysis corneal epithelium cell fluorescence alamarBlue assay rhodamine dye animal welfare toxic injury degraded mitochondria epithelial monolayer disinfectants membrane integrity eye toxicity eye viability dye toxicity in humans human toxicity effects on the mitochondria mitochondrial toxicity in vitro battery in vitro test battery ophthalmic eye drop direct contact product safety cytotoxicity potential molecular molecular biology refine reduce replace sensitivity and relevance sensitivity relevance rabbit ocular irritation test product development cytotoxicity models cytotoxicity alternative methods replacements for animal testing three r's beagle tiered testing tiered testing strategy replacements animal testing mechanistic toxicity cornea mitochondria dose response threshold Vision Science and Biology
119	Development of Sensitive In Vitro Assays to Assess the Ocular Toxicity Potential of Chemicals and Ophthalmic Products McCanna, David January 2009 (has links) The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes. The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations. in vitro Alternative Methods alamarBlue rhodamine tight junctions bovine lens viability toxicity mitochondria mitochondria integrity benzalkonium chloride sodium dodecyl sulphate sodium lauryl sulfate scanning electron microscopy Draize Draize maximal average scores zonula occludens cosmetic directive PETA humane society animal league ICCVAM ECVAM JaCVAM BCOP bovine cornea ocular irritants ocular irritation ocular toxicity human corneal epithelial cells vitro confocal confocal microscopy metabolic activity optical quality reactive oxygen species contact lens contact lens care solutions barrier function microbial keratitis mulitipurpose solutions tight junction cell damage claudin ZO-1 occludin MDCK Madin Madin-Darby canine kidney cells cornea human cornea human corneal epithelium epithelial cell line human corneal epithelial cell line sodium fluorescein sodium fluorescein permeability fluorescein permeability ocular surface cell monolayer Araki-Sasaki cell physiology risk assessment safety assessment ScanTox scanning laser lens epithelium corneal cells in vitro model ophthalmic formulations multiple instillation back vertex animal testing rabbit testing alternatives to animal testing cultured bovine lens toxicity of chemicals irritation irritants laser scanner organ culture delayed toxicity toxins hydrogen peroxide cornea toxicity cornea toxicity models prediction of human toxicity no observable adverse effect level lowest observable adverse effect level NOAEL LOAEL toxicity thresholds safety factors cornea uncertainty factors preservatives disinfectants ophthalmic products preclinical preclinical testing epithelial barrier drug penetration clinical confocal microscopy animal rights rabbit cornea human cornea human clinical effects toxic animal rights activist sensitive measures toxic effect toxicity threshold agar overlay agar diffusion agar overlay method agar diffusion method cytochrome cytochrome c apoptosis necrotic apoptotic necrosis caspase rhodamine 123 resazuran resorufin cell death cell viability metabolic dye microsomal microsomal enzymes cytotoxicity cytotoxic cytotoxic effect MTT XTT WST-1 plasma membrane mitochondrial mitochondrial morphology ocular toxicity potential ocular toxicity human corneal epithelial cell line confocal analysis corneal epithelium cell fluorescence alamarBlue assay rhodamine dye animal welfare toxic injury degraded mitochondria epithelial monolayer disinfectants membrane integrity eye toxicity eye viability dye toxicity in humans human toxicity effects on the mitochondria mitochondrial toxicity in vitro battery in vitro test battery ophthalmic eye drop direct contact product safety cytotoxicity potential molecular molecular biology refine reduce replace sensitivity and relevance sensitivity relevance rabbit ocular irritation test product development cytotoxicity models cytotoxicity alternative methods replacements for animal testing three r's beagle tiered testing tiered testing strategy replacements animal testing mechanistic toxicity cornea mitochondria dose response threshold Vision Science and Biology

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