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See detailTowards a system of concepts for Family Medicine. Multilingual indexing in General Practice/ Family Medicine in the era of Semantic Web
Jamoulle, Marc ULiege

Doctoral thesis (2017)

UNIVERSITY OF LIÈGE, BELGIUM Executive Summary Faculty of Medicine Département Universitaire de Médecine Générale. Unité de recherche Soins Primaires et Santé Doctor in biomedical sciences Towards a ... [more ▼]

UNIVERSITY OF LIÈGE, BELGIUM Executive Summary Faculty of Medicine Département Universitaire de Médecine Générale. Unité de recherche Soins Primaires et Santé Doctor in biomedical sciences Towards a system of concepts for Family Medicine. Multilingual indexing in General Practice/ Family Medicine in the era of SemanticWeb by Dr. Marc JAMOULLE Introduction This thesis is about giving visibility to the often overlooked work of family physicians and consequently, is about grey literature in General Practice and Family Medicine (GP/FM). It often seems that conference organizers do not think of GP/FM as a knowledge-producing discipline that deserves active dissemination. A conference is organized, but not much is done with the knowledge shared at these meetings. In turn, the knowledge cannot be reused or reapplied. This these is also about indexing. To find knowledge back, indexing is mandatory. We must prepare tools that will automatically index the thousands of abstracts that family doctors produce each year in various languages. And finally this work is about semantics1. It is an introduction to health terminologies, ontologies, semantic data, and linked open data. All are expressions of the next step: Semantic Web for health care data. Concepts, units of thought expressed by terms, will be our target and must have the ability to be expressed in multiple languages. In turn, three areas of knowledge are at stake in this study: (i) Family Medicine as a pillar of primary health care, (ii) computational linguistics, and (iii) health information systems. Aim • To identify knowledge produced by General practitioners (GPs) by improving annotation of grey literature in Primary Health Care • To propose an experimental indexing system, acting as draft for a standardized table of content of GP/GM • To improve the searchability of repositories for grey literature in GP/GM. 1For specific terms, see the Glossary page 257 x Methods The first step aimed to design the taxonomy by identifying relevant concepts in a compiled corpus of GP/FM texts. We have studied the concepts identified in nearly two thousand communications of GPs during conferences. The relevant concepts belong to the fields that are focusing on GP/FM activities (e.g. teaching, ethics, management or environmental hazard issues). The second step was the development of an on-line, multilingual, terminological resource for each category of the resulting taxonomy, named Q-Codes. We have designed this terminology in the form of a lightweight ontology, accessible on-line for readers and ready for use by computers of the semantic web. It is also fit for the Linked Open Data universe. Results We propose 182 Q-Codes in an on-line multilingual database (10 languages) (www.hetop.eu/Q) acting each as a filter for Medline. Q-Codes are also available under the form of Unique Resource Identifiers (URIs) and are exportable in Web Ontology Language (OWL). The International Classification of Primary Care (ICPC) is linked to Q-Codes in order to form the Core Content Classification in General Practice/Family Medicine (3CGP). So far, 3CGP is in use by humans in pedagogy, in bibliographic studies, in indexing congresses, master theses and other forms of grey literature in GP/FM. Use by computers is experimented in automatic classifiers, annotators and natural language processing. Discussion To the best of our knowledge, this is the first attempt to expand the ICPC coding system with an extension for family physician contextual issues, thus covering non-clinical content of practice. It remains to be proven that our proposed terminology will help in dealing with more complex systems, such as MeSH, to support information storage and retrieval activities. However, this exercise is proposed as a first step in the creation of an ontology of GP/FM and as an opening to the complex world of Semantic Web technologies. Conclusion We expect that the creation of this terminological resource for indexing abstracts and for facilitating Medline searches for general practitioners, researchers and students in medicine will reduce loss of knowledge in the domain of GP/FM. In addition, through better indexing of the grey literature (congress abstracts, master’s and doctoral theses), we hope to enhance the accessibility of research results and give visibility to the invisible work of family physicians. [less ▲]

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See detailA TMS–EEG contribution to the multimodal assessment of brain connectivity and consciousness
BODART, Olivier ULiege

Doctoral thesis (2017)

Patients with chronic disorders of consciousness make a challenging population. On the clinical side, establishing an accurate diagnosis is arduous, as the signs of consciousness can be subtle, or even ... [more ▼]

Patients with chronic disorders of consciousness make a challenging population. On the clinical side, establishing an accurate diagnosis is arduous, as the signs of consciousness can be subtle, or even undetectable behaviourally. Both the families and the caregivers need truthful information to make tough decisions about the patient’s management. Transcranial magnetic stimulation, coupled with high-density electroencephalography, is a promising technique to improve our diagnostic ability. The perturbational complexity index derived from this technique is able to distinguish between unconscious and conscious conditions. Its specificity remains to be determined. On the scientific side, the long-standing quest to discover the neural correlates of consciousness is still ongoing. Patients with disorders of consciousness have structural brain damage, and several areas may lose their ability to causally interact in complex patterns with long distance structure. The relation between this ability and structural integrity remains undetermined, despite a vast amount of neuroimaging studies on several networks and connectivities in this population. Our objectives are i) to cross-validate the perturbational complexity index with other neuroimaging techniques, and to determine its specificity, and ii) to determine the relation between global structural integrity and the brain global ability to sustain complex long-range interactions. To do so, we first combined transcranial magnetic stimulation with fluoro-deoxyglucose positron emission tomography, a validated technique studying the brain metabolism, in a population of patients behaviourally characterized by repeated assessments with the gold standard scale, the coma recovery scale – revised. To meet our second objective, we computed and compared the perturbational complexity index and the global fractional anisotropy, a magnetic resonance imaging marker of structural integrity, in patients and in healthy subjects. We found an excellent congruence between electrophysiological and metabolic results in our first study, even in behaviourally unconscious patients showing indirect signs of consciousness. In our second study, we demonstrated that structural integrity largely correlated with the perturbational complexity index, and did not depend on the time since onset or the aetiology. This confirms the diagnostic value of transcranial magnetic stimulation and the perturbational complexity index. It is not only sensitive at the single subject level, but also highly specific. It can detect covert signs of consciousness, as confirmed by other neuroimaging techniques. As such, it could be integrated in diagnostic algorithms and improve their accuracy, leading to better management of these patients. Moreover, the brain’s ability to sustain complex long-range interactions is highly dependant on the global structural integrity. By looking further in detail at the local correlation between these two parameters, our understanding of the emergence of consciousness from fixed structure with variable connectivity would improve. This would be one step forward in the quest for the neural correlates of consciousness. [less ▲]

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See detailRôle des lymphocytes T TCR γδ dans la progression des lésions associées à l'infection par les papillomavirus humains
Van Hede, Dorien ULiege

Doctoral thesis (2017)

Cervical cancer was the fourth most frequent cancer in women in 2012, with the majority of cases occurring in less developed countries. Although this cancer is induced by Human Papillomavirus (HPV ... [more ▼]

Cervical cancer was the fourth most frequent cancer in women in 2012, with the majority of cases occurring in less developed countries. Although this cancer is induced by Human Papillomavirus (HPV) infections that have a high prevalence, only a very few percentage of infected women will developed this disease. Host immune defenses are essential to clear infection and to kill virus-infected transformed cells. Indeed, majority of infected women clear the virus within two years while immunocompromised patients are more likely to develop cervical preneoplastic lesions and cancers. γδ T cells have been shown to protect against the formation of squamous cell carcinoma (SCC) in several models. Nowadays, the contribution of γδ T cells in HPV associated uterine cervical SCC is unknown. Here we investigated the impact of γδ T cells in a transgenic mouse model of carcinogenesis induced by HPV16-oncoproteins. Surprisingly, γδ T cells promoted the development of HPV16-oncoprotein-induced lesions. These oncoproteins induced a decrease in epidermal Skint-1 expression and modification of the associated anti-tumor Vγ5+ γδ T cells (or DETC), which were joined by other γδ T cell subsets actively producing IL-17. Consistent with a proangiogenic role, γδ T cells promoted the formation of blood vessels in the dermis underlying the HPV-induced lesions. In human cervical, IL-17+ γδ T cells could be only observed at the cancer stage (SCC) (but not in less advanced cervical lesions), where HPV oncoproteins are highly expressed, supporting the clinical relevance of our observations in mice. Overall, our results suggest that HPV16-oncoproteins induce a reorganization of the local epithelial-associated γδ T cell Subpopulations thereby promoting angiogenesis and cancer development. [less ▲]

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See detailField border flowering strips as a source of valuable compounds
Paul, Aman ULiege

Doctoral thesis (2017)

Intensification of agricultural practices has caused irreversible damage to environment during the last few years. Several consumers are now deviating towards healthier diets produced from eco-friendly ... [more ▼]

Intensification of agricultural practices has caused irreversible damage to environment during the last few years. Several consumers are now deviating towards healthier diets produced from eco-friendly and sustainable agricultural systems. In this regard, the possibilities of utilizing edible biomass originating from sustainable agricultural practices have gained recent attention. The underutilized edible plants, especially their seeds could be one of the interesting alternates, as some of these seeds are not only nutritious, but could also be produced using sustainable practices. Similarly, edible insects represent another category of biomass which are rich in nutrients and could be produced sustainably. The seeds from underutilized edible plants and the edible insects could be simultaneously harvested using a sustainable agricultural system involving field border flowering strips. Field border flowering strip is a part of agricultural landscape that is reserved for herbaceous vegetation. These strips are popularly grown throughout the world to enhance biodiversity. The main objective of this thesis is to utilize seeds from some of the plants grown as field border flowering strips and insects that find refuge in these plants for the provision of food and health promoting substances. From the literature reviewed in chapter two, it was observed that: (1). Most plants that are grown in field border flowering strips are edible, and their aerial parts have been extensively analyzed for chemical composition. However, there is a scarcity of literature evaluating chemical composition/food utilization of the seeds from plants that are grown as field border flowering strips. So, the primary objective of this thesis is to investigate the nutritional and health promoting potential of the seeds from some plants that are grown in these strips. (2). A number of grasshopper species find refuge in field border flowering strips. Several grasshopper species are considered edible throughout the world and they are interesting source of nutrients. So the secondary objective of this thesis is to screen some edible grasshopper species that are present in field border flowering strips, analyze their nutritional value, and investigate possibilities to establish their commercial rearing for ensuring year-long availability of edible biomass. The research strategy adopted to achieve the objectives of this thesis is mentioned in chapter three. This chapter includes details about the selection of raw materials (both plant seeds and insects), and subsequent analysis. Chapter four contains the detail about the materials and methods used for analysis during this study. Chapter five includes details about the investigations on edible insects. Chorthippus parallelus Zetterstedt species grasshoppers were shortlisted for detailed investigation due to their high densities in field border flowering strips. This insect species was analyzed for proximate composition, amino acid profile, fatty acid profile and mineral profile. Moreover the toxicity of these insects was also evaluated using two different models. Results indicated that these insects could be consumed as an alternate source of proteins (69%) and omega-3 fatty acid rich lipids (10%). Rearing trials done during this study indicates that commercial rearing could be developed to produce sufficient and safe biomass for human consumption. The selection of seeds from three plant species (Achillea millefolium L., Anthriscus sylvestris (L). Hoffm. and Prunella vulgaris L.), for detailed analysis on the basis of lipid content and fatty acid profile has been mentioned in chapter six. Chapter seven, eight and nine include the details about the composition and anti-oxidant activity of A. millefolium, A. sylvestris and P. vulgaris seeds, respectively. Proximate composition, lipid profile, amino acid profile, mineral profile, lignocellulosic profile, phenolic profile and phytate content of the three plant seeds were investigated during this study. Two new phenolic acids were discovered originating from P. vulgaris seeds. These compounds were named amolsamic acid A and amolsamic acid B. Discovery of these compounds was the true highlight of this thesis. All the three plant seeds were found to contain substantial level of total phenolics (0.8-2.6%) and interesting phenolic profiles (dominated by chlorogenic acid, rosmarinic acids and related compounds). Keeping this in mind, the detailed anti-oxidant activity (including anti-radical scavenging, horseradish peroxidase response modulation, cellular anti-oxidant, myeloperoxidase response modulation and anti-lipid peroxidation activity) of their respective seed extracts was also analyzed. Results obtained during this study indicate that A. millefolium, A. sylvestris and P. vulgaris seeds not only contain interesting level of nutrients, but their extracts also exhibit significant anti-radical scavenging, horseradish peroxidase response modulation, cellular anti-oxidant (IC50 values order: P. vulgaris>A. sylvestris>A. millefolium) and myeloperoxidase response modulation activity (IC50 values order: A. sylvestris>A. millefolium>P. vulgaris for both direct and SIEFED assay). The main conclusions (chapter ten) of this PhD dissertation are: (1). C. parallelus insects could be viewed as an alternative source of nutrients to diversify human diets. The preliminary rearing studies done during this study indicate that commercial rearing could be developed for generation of substantial (and safe) biomass to support human consumption. (2). A. millefolium, A. sylvestris and P. vulgaris seeds could be included in food formulations (or consumed as whole) as a source of proteins, lipids, minerals and phenolics. P. vulgaris seeds could also be used for the extraction of two new phenolic constituents (amolsamic acid A and amolsamic acid B). The first investigations involving A. millefolium, A. sylvestris and P. vulgaris seeds realized during this study, indicate that seed extract (or whole seeds) from all three plants could possibly be consumed for the prevention of neutrophil and myeloperoxidase mediated damage in human body. [less ▲]

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See detailNouvelles combinaisons thérapeutiques pour améliorer l'efficacité anti-tumorale de l'inhibition d'HDAC5
Hendrick, Elodie ULiege

Doctoral thesis (2017)

En oncologie, les 18 membres de la famille des déacétylases d’histone (HDAC) représentent des cibles thérapeutiques d’intérêt croissant. En effet, de nombreuses molécules pharmacologiques ciblant ... [more ▼]

En oncologie, les 18 membres de la famille des déacétylases d’histone (HDAC) représentent des cibles thérapeutiques d’intérêt croissant. En effet, de nombreuses molécules pharmacologiques ciblant l’activité enzymatique de ces protéines (HDACi) montrent des effets anti-tumoraux intéressants in vitro et in vivo ainsi que dans de nombreux essais cliniques sur des patients souffrant de pathologies cancéreuses solides et hématologiques. A ce jour, 4 de ces molécules (Vorinostat®, l’Istodax®, Beleodaq® et le Farydak®) sont d’ailleurs approuvées par la FDA et l’EMA pour le traitement de patients souffrant, notamment, de différents types de lymphomes et de myélomes. Aujourd’hui, les oncologues s’intéressent au développement d’inhibiteurs d’HDAC plus sélectifs avec comme objectifs de maintenir et d’améliorer l’effet anti-tumoral tout en diminuant la toxicité et en réduisant les potentiels effets non désirés. Dans cette optique, il convient de déterminer plus finement les relations qu’il existe entre l’inhibition spécifique d’une HDAC et les effets anti- tumoraux observés et ce, afin d’identifier la (les) HDAC d’intérêt à cibler en thérapie anti-cancéreuse. Dans ce travail, nous nous sommes focalisés sur le rôle et les mécanismes d’action de l’histone déacétylase 5 (HDAC5) dans les cellules cancéreuses. Nos résultats démontrent que l’inhibition sélective d’HDAC5 module l’expression de protéines du complexe I de la chaîne respiratoire mitochondriale, de protéines pro- et anti- oxydantes et des protéines impliquées dans le métabolisme de métaux tel que le métabolisme de stockage du fer labile. Par conséquent, la déplétion d’HDAC5 induit une production accrue d’espèces réactives de l’oxygène (ROS) mitochondriaux accentués par la présence accrue de fer labile intracellulaire disponible pour la réaction de Fenton. Cette accumulation accrue de ROS induit une mort cellulaire par apoptose et un processus d’autophagie de type mitophagie (dégradation sélective des mitochondries endommagées et productrice de ROS). La déplétion d’HDAC5 dans des cellules cancéreuses modifie également le métabolisme énergétique dépendant du glucose et de la glutamine. Nous avons effectivement observé d’une part, une augmentation de l’import du glucose dirigé vers la voie des pentoses phosphates assurant une production de NADPH, force réductrice du glutathion permettant ainsi de contrecarrer le stress oxydant et d’autre part, une glutamino-dépendance nécessaire au maintien des besoins énergétiques de la cellule. Par conséquent, des cellules déplétées en HDAC5 dont l’apport en glucose ou en glutamine est contrecarré par des inhibiteurs métaboliques utilisés en clinique, meurent de manière significative par apoptose in vitro et diminuent la croissance de tumeurs in vivo, suggérant que des stratégies combinatoires couplant l’inhibition sélective d’HDAC5 à des inhibiteurs du métabolisme énergétique actuellement testés en essai clinique pourraient être proposées comme nouvelle stratégie combinatoire en thérapie anti-cancéreuse. [less ▲]

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See detailLes Hormones Glycoprotéiques: de la Clinique à la Recherche.
VALDES SOCIN, Hernan Gonzalo ULiege

Doctoral thesis (2017)

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See detailL’INHIBITION DE LA MÉTHYLTRANSFÉRASE EZH2 DU COMPLEXE RÉPRESSEUR POLYCOMB FAVORISE LA RÉPONSE ANTI-TUMORALE DES MACROPHAGES M2 DIRIGÉE CONTRE LES CELLULES DU MÉSOTHÉLIOME PLEURAL MALIN
Hamaïdia, Malik ULiege

Doctoral thesis (2017)

Context: Malignant pleural mesothelioma (MPM) is an aggressive neoplasm affecting mesothelial cells from the pleura, pericardium and peritoneum. The disease is closely associated to asbestos exposure ... [more ▼]

Context: Malignant pleural mesothelioma (MPM) is an aggressive neoplasm affecting mesothelial cells from the pleura, pericardium and peritoneum. The disease is closely associated to asbestos exposure. Despite of rules to reduce workplace exposure to asbestos, incidence of mesothelioma is predicted to increase until 2020. Since MPM is resistant to conventional cancer therapies such as surgery, irradiation and chemotherapy, development of new options is urgently needed. In my project, I investigate the ability of immunotherapy to improve patients' outcome. My hypothesis postulates that tumor cells are tightly controlled by the immune system. In fact, clinical evidence indicates that tumor infiltration by tumor associated macrophages (TAMs) correlates with poor prognosis in malignant mesothelioma (MM). By attenuating the immune response, TAMs indeed promote survival of MM cells. TAMs share properties with alternative macrophages (M2) and are activated by anti-inflammatory (e.g. IL-10) or Th2-associated (i.e. IL-4, IL-13) cytokines. In contrast, classical (M1) macrophages are stimulated by interferon (IFN)-γ and microbial components (e.g. LPS). Aim: We hypothesized that macrophage activation is mediated by a transcriptional program tightly regulated by epigenetic modifications. We focused on the Polycomb Repressive Complex 2 (PRC2) EZH2 lysine methyltransferase responsible for trimethylation of histone H3 at lysine 27 (H3K27me3). Results: Our data show that inhibition of EZH2 reduces phagocytic activity by M2-polarised macrophages. Moreover, the cytotoxicity of supernatants conditioned by M2-macrophages is increased in presence of the EZH2 inhibitor. Finally, inhibition of EZH2 enhances the tumoricidal potential of M2 macrophages towards MM cells. We further demonstrate that macrophage killing activity requires superoxide radicals (O2.-) and peroxynitrites (ONOO-) derivatives produced by the NADPH oxidase system. Conclusion: EzH2 inhibition implements the tumoricidal potential of macrophages and may therefore improve the efficacy of immunotherapy of MM patients. [less ▲]

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See detailInactivation of DNA damage repair provides additional efficacy to the treatment of thyroid cancer
Neelature Sriramareddy, Sathyanarayana ULiege

Doctoral thesis (2017)

Incidence of thyroid cancer has increased steadily over the last several decades. This type of neoplasm accounts for the majority of deaths due to endocrine cancers. The most frequent form, well ... [more ▼]

Incidence of thyroid cancer has increased steadily over the last several decades. This type of neoplasm accounts for the majority of deaths due to endocrine cancers. The most frequent form, well-differentiated thyroid cancer, is characterized by disease persistence, recurrence and a lack of response to radioiodine-131. With survival rates of 9 weeks to 5 months, anaplastic thyroid cancer has very poor prognosis. To provide additional efficacy to the treatment of thyroid cancer, we investigated the mechanisms of DNA damage and repair. We found that thyroid cancer cells undergo mitosis in presence of unrepaired DNA damage. To proliferate and survive, these cells repair DNA lesions very efficiently using homologous recombination (HR) and non-homologous end joining (NHEJ). Pharmacological inhibition of these pathways significantly increases apoptosis of thyroid cancer cells. This thesis thus demonstrates that targeting DNA damage repair pathways might have therapeutic value in relapsing and advanced thyroid cancers. [less ▲]

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See detailLa faisabilité et l'efficacité du traitement assisté par diacétylmorphine en Belgique
Demaret, Isabelle ULiege

Doctoral thesis (2016)

Objective The aim of our research was to assess the feasibility and efficacy of a treatment assisted by diacetylmorphine in Liège. This treatment is offered to persons dependent on heroin who pursue ... [more ▼]

Objective The aim of our research was to assess the feasibility and efficacy of a treatment assisted by diacetylmorphine in Liège. This treatment is offered to persons dependent on heroin who pursue street heroin use despite existing treatments. Methods Data were collected in a pilot project of Treatment Assisted by Diacetylmorphine (TADAM), which took place in Liège from 2007 to 2013. The heart of this project is a randomised controlled trial comparing a diacetylmorphine treatment – limited to 12 months – with existing methadone treatments. A participant was responder if he/she showed improvement on the level of street heroin use, health or criminal involvement. Other researches (mainly based on interviews) were added in order to understand interactions between the trial and its actors: heroin users (included or not-included), neighbours of the DAM centre, the staff of the DAM centre and staff of other institutions who worked with our target group in Liège. Results With the help of the centres, partners of the trial, 74 participants (of the 200 planned) were included and randomised: 36 in the experimental group and 38 in the control group. These participants were dependent on heroin for 20 years on average and had already tried 9 treatments for their addiction(s). At the end of the trial, the number of responders in the experimental group was greater but not significantly than in the control group (p=0.35). However, participants in the experimental group showed greater improvement than in the control group, on the level of street heroin use (p=0.0011) and physical (p=0.043) or mental (p=0.035) health. During the follow-up study, three months after the end of the 12 months of treatment, street heroin use in the experimental group had significantly increased (p=0.0052) and the difference with the control group was no longer significant (p=0.55). Discussion Participants included in the trial were, as expected, persons severely dependent on street heroin, who could not find a solution to their addiction with the existing treatments. Participants in the experimental group decreased significantly their street heroin use. However, in our follow-up study, street heroin use increased significantly in the experimental group 3 months after the end of the diacetylmorphine treatment. In the foreign studies, diacetylmorphine treatment showed greater efficacy compared to methadone treatment for this target group and the improvement was sustained after the trial even when the treatment was stopped, but not when the end of treatment was forced against the will of the patient. Nevertheless, our research showed the feasibility of a diacetylmorphine treatment in Liège and its acceptance by the actors involved in the trial. Conclusion Diacetylmorphine treatment is feasible in Belgium. In foreign studies, it showed more efficacy than methadone treatment and benefits gained with this approach were maintained during years. But these benefits disappear when the end of treatment is forced, against the will of the patient. [less ▲]

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See detailLes enregistrements infirmiers : un outil d'efficience. Du RIM aux DI-RHM dans les hôpitaux belges.
Thonon, Olivier ULiege

Doctoral thesis (2016)

Le Résumé Infirmier Minimum existe depuis 1988 et un certain nombre des objectifs initiaux ont été atteints. A la fin des années 90, la question de l’actualisation du RIM s’est posée avec acuité étant ... [more ▼]

Le Résumé Infirmier Minimum existe depuis 1988 et un certain nombre des objectifs initiaux ont été atteints. A la fin des années 90, la question de l’actualisation du RIM s’est posée avec acuité étant donné l’évolution des soins de santé en général et de l’art infirmier en particulier. Dorénavant intégré dans une base de données unique, le Résumé Hospitalier Minimal, ce Résumé Infirmier Minimum actualisé, implanté officiellement depuis janvier 2008, a sans aucun doute métamorphosé l’environnement des soins infirmiers. Le chapitre 1 décrit ce processus d’actualisation du RIM. Le cadre conceptuel du RIM « actualisé » définit un tremplin international, en référence à la Nursing Interventions Classification (NIC) utilisée pour sa conception. La visualisation de la variabilité des soins infirmiers se fera dorénavant à travers un langage plus riche et plus précis en passant de 23 à 78 items. La première composante de l’efficience, est abordée dans le chapitre III. Il concerne l’évaluation du niveau de preuve des interventions répertoriées dans les DI-RHM. L’approche justificative de l’outil est abordée dans le chapitre IV de ce travail. Le chapitre V examine dans quelle mesure il serait possible d’allouer les moyens infirmiers de façon plus rigoureuse aux hôpitaux. Le chapitre VI se consacre à l’élaboration de profils de soins infirmiers sur base des DI-RHM et à la mise en évidence de leur potentiel d’utilisation. Nous concluons par une discussion générale reprenant les divers éléments abordés dans ces différentes approches à la lumière du contexte actuel de l’outil. [less ▲]

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See detailMethods and models for brain connectivity assessment across levels of consciousness
Amico, Enrico ULiege

Doctoral thesis (2016)

The human brain is one of the most complex and fascinating systems in nature. In the last decades, two events have boosted the investigation of its functional and structural properties. Firstly, the ... [more ▼]

The human brain is one of the most complex and fascinating systems in nature. In the last decades, two events have boosted the investigation of its functional and structural properties. Firstly, the emergence of novel noninvasive neuroimaging modalities, which helped improving the spatial and temporal resolution of the data collected from in vivo human brains. Secondly, the development of advanced mathematical tools in network science and graph theory, which has recently translated into modeling the human brain as a network, giving rise to the area of research so called Brain Connectivity or Connectomics. In brain network models, nodes correspond to gray-matter regions (based on functional or structural, atlas-based parcellations that constitute a partition), while links or edges correspond either to structural connections as modeled based on white matter fiber-tracts or to the functional coupling between brain regions by computing statistical dependencies between measured brain activity from different nodes. Indeed, the network approach for studying the brain has several advantages: 1) it eases the study of collective behaviors and interactions between regions; 2) allows to map and study quantitative properties of its anatomical pathways; 3) gives measures to quantify integration and segregation of information processes in the brain, and the flow (i.e. the interacting dynamics) between different cortical and sub-cortical regions. The main contribution of my PhD work was indeed to develop and implement new models and methods for brain connectivity assessment in the human brain, having as primary application the analysis of neuroimaging data coming from subjects at different levels of consciousness. I have here applied these methods to investigate changes in levels of consciousness, from normal wakefulness (healthy human brains) or drug-induced unconsciousness (i.e. anesthesia) to pathological (i.e. patients with disorders of consciousness). [less ▲]

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See detailNietzsche & la neurologie
JEDIDI, Haroun ULiege

Master of advanced studies dissertation (2016)

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See detailContribution to the study of the mineral hypothesis in relation to the Kashin-Beck disease in Tibet Autonomous Region
DERMIENCE, Michael ULiege

Doctoral thesis (2016)

A little known disease called Kashin-Beck disease (KBD) plagues the poor and rural populations in the Tibet Autonomous Region (T.A.R.) and in other provinces of the People’s Republic of China. It is an ... [more ▼]

A little known disease called Kashin-Beck disease (KBD) plagues the poor and rural populations in the Tibet Autonomous Region (T.A.R.) and in other provinces of the People’s Republic of China. It is an endemic and chronic osteochondropathy affecting long bones and joints, sometimes as soon as of the early childhood. Although the etiology of this disease is not clearly established, little doubt remains as to the implication of multiple environmental factors. Intoxication by mycotoxins in cereals and by organic acids in water, deficiencies in selenium and iodine, are all factors having a place in the multifactorial etiology hypothesized. In T.A.R., diet, notably, differentiates the rural community, affected by KBD, from the other communities (nomads and city-dwellers), who remain unaffected. Because more than one chemical element is essential to a healthy bone metabolism, and because there is scarce data, if not any, on the topic, this thesis had to primary objective to investigate the mineral and trace element dietary status of young Tibetan children living in areas endemic for KBD. The first logical action step led us to determine which elements are involved in bone and joints metabolism through an exhaustive review of the scientific literature. Thirty elements were highlighted, and a dozen was deemed relevant in this context. An exploratory study on the Tibetan food composition concluded on a high risk of introducing important bias by using the existing food composition tables for nutritional assessment in T.A.R. Being inescapable tools, a specific food composition table was elaborated for our area of investigation with the close collaboration of the China National Center for Food Safety Risk Assessment (CFSA). During a scientific internship of 7 month in the CFSA, 19 chemical elements were analyzed in not less than 1119 samples of sixteen traditional foods and beverages of rural T.A.R. In order to assess the nutritional status of the children, a cross-sectional study was implemented. 250 preschool children aged 3 to 5 years old from three rural counties around Lhasa were enrolled. They were interviewed twice, at six month of interval, via the 24-hour recall method. The results suggest several imbalances in their dietary mineral intakes compared to the Chinese recommendations. Sodium and manganese intakes are too high, while they are too low for potassium, calcium, zinc, copper and selenium. The Tibetan diet is rich in fiber and in phytic acid, which are susceptible to decrease the bioavailability and to aggravate the deficiencies of the later elements. For this reason, we conducted an animal experimentation on a rat model to assess the apparent digestibility, the fecal excretion and the urinary excretion of minerals and trace elements in the traditional Tibetan dish called tsampa pag. This traditional dish consisting of roasted barley flour mixed with yak butter tea is the mainstay of the Tibetan diet. The results of this experiment suggest low bone mineral density, a possible secondary copper deficiency, and a possible manganese excess in rats that consumed tsampa pag. In view of the results presented, it would be interesting to compare the mineral intake between children living in endemic areas and in non-endemic areas. It would also be interesting to include more of elements known to affect bone metabolism in future studies. [less ▲]

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See detailActivation de la coagulation par la Transition Epithélio-Mésenchymateuse: impact sur la colonisation métastatique
Bourcy, Morgane ULiege

Doctoral thesis (2016)

Au cours de la cascade métastatique, des cellules tumorales quittent la tumeur primaire et envahissent le sang (Cellules Tumorales Circulantes, CTCs) pour former des métastases dans des organes ... [more ▼]

Au cours de la cascade métastatique, des cellules tumorales quittent la tumeur primaire et envahissent le sang (Cellules Tumorales Circulantes, CTCs) pour former des métastases dans des organes secondaires. Le processus métastatique est hautement sélectif et seule une faible proportion de CTCs survit dans la circulation et colonise les sites secondaires pour former des métastases. Les cellules tumorales subissent des changements phénotypiques qui leur procurent des propriétés migratoires et invasives ainsi que des capacités de survie accrue leur permettant de franchir ces différentes étapes. A ce jour, il est largement accepté que les processus de Transition Epithélio-Mésenchymateuse (TEM) sont impliqués dans cette plasticité cellulaire et participent à la libération et à la biologie des CTCs. Des données de la littérature indépendantes ainsi que des résultats du laboratoire suggèrent, par ailleurs, que les processus de coagulation pourraient favoriser les étapes précoces de la dissémination métastatique (survie, persistance, arrêt et extravasation). Au cours de ce travail de doctorat, nous avons examiné l’acquisition potentielle de propriétés pro-coagulantes par les CTCs dérivées d’une TEM impliquant l’expression du Facteur Tissulaire (FT), l’initiateur cellulaire clé de la cascade de coagulation. De telles propriétés coagulantes permettraient la formation d’une matrice de fibrine protectrice autour des CTCs favorisant, ainsi, leur survie dans la circulation sanguine et la colonisation métastatique. A l’aide de divers modèles cellulaires in vitro, nous avons montré que les processus de TEM sont associés à une expression accrue du FT et à des propriétés pro-coagulantes. Ensuite, nous avons fonctionnellement lié les processus de TEM à ces régulations en y impliquant des facteurs de transcription de la TEM, ZEB1 et Snail. De plus, en utilisant des modèles de métastases expérimentales, nous avons montré que l’axe TEM/FT/coagulation procure aux CTCs des propriétés de survie et des capacités de colonisation métastatique accrues. Enfin, nous avons apporté une validation clinique à ces résultats en observant des CTCs positives pour le FT et la vimentine, un marqueur mésenchymateux, dans le sang de patientes atteintes d’un cancer du sein métastatique. L’ensemble de nos résultats met en évidence un nouvel axe de régulation TEM/FT permettant une activation locale de la coagulation par les CTCs TEM+ favorisant la colonisation métastatique précoce. [less ▲]

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See detailDéveloppement et optimisation de nanovecteurs de type lipoplexes pour une application vaginale en vue de traiter des lésions induites par HPV
Lechanteur, Anna ULiege

Doctoral thesis (2016)

Le cancer du col de l’utérus est associé à une infection par des papillomavirus à haut risque (HPV-HR) et est le troisième cancer le plus meurtrier chez la femme, à travers le monde. Bien que des vaccins ... [more ▼]

Le cancer du col de l’utérus est associé à une infection par des papillomavirus à haut risque (HPV-HR) et est le troisième cancer le plus meurtrier chez la femme, à travers le monde. Bien que des vaccins prophylactiques soient commercialisés, la prévalence est actuellement de 12 % et les traitements proposés sont liés à de nombreux effets indésirables et des risques importants de comorbidités. Le développement d’un nouveau traitement moins agressif et efficace contre des lésions (pré)cancéreuses induites par plusieurs HPV-HR serait donc intéressant. L’utilisation des small interfering RNA (siRNA) est actuellement une approche thérapeutique attractive contre de nombreuses pathologies comme les infections virales ou les cancers. Cependant, la stabilité et l’efficacité des siRNA sont conditionnées par le développement de nanovecteurs qui permettent de véhiculer les siRNA au travers des barrières biologiques. Le but de ce travail est de développer un nouveau traitement des lésions cervicales (pré)néoplasiques induites par HPV, grâce à une application topique de siRNA encapsulés dans des liposomes PEGylés. Pour ce faire, nous avons tout d’abord sélectionné une combinaison de siRNA efficace contre plusieurs lignées cellulaires HPV 16 et HPV 18 positives. Cette combinaison cible simultanément les ARNm codant pour l’oncoprotéine E7 du génome HPV 16 et pour la protéine ubiquitaire anti-apoptotique MCL-1. Nous avons ensuite développé plusieurs lipoplexes recouverts de différents types de PEG, les DSPE-PEG2000, les DSPE-PEG750 et les Céramide-PEG2000, greffés en différentes densités. Cette étude a mis en évidence les propriétés physico-chimiques déterminant l’efficacité des siRNA et la toxicité du nanovecteur. Suite à ces essais, la formulation de lipoplexes contenant 20 % de Céramide-PEG2000, efficace et non toxique a été sélectionnée. Enfin, la capacité de cette formulation à diffuser dans le mucus cervico-vaginal et à pénétrer au sein d’une muqueuse vaginale a été évaluée in vitro, ex vivo et in vivo. Les lipoplexes contenant 20 % de Céramide-PEG2000 semblent diffuser efficacement dans le mucus et distribuer le siRNA dans toutes les couches de l’épithélium. Le nouveau nanovecteur lipidique développé dans ce travail semble être un candidat adéquat pour l’administration de siRNA au niveau vaginal, dans le but de traiter des lésions (pré)cancéreuses induites par l’infection d’HPV-HR. [less ▲]

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See detailPrévalence de l’hypovitaminose D chez la femme enceinte : quelle est la situation en région liégeoise ?
VRANKEN, Laura ULiege

Master of advanced studies dissertation (2016)

Vitamin D deficiency is a worldwide health problem, also during pregnancy, especially in women with limited access to sunlight due to minimal outdoor activity or heavy use of sunscreen, cultural practices ... [more ▼]

Vitamin D deficiency is a worldwide health problem, also during pregnancy, especially in women with limited access to sunlight due to minimal outdoor activity or heavy use of sunscreen, cultural practices or traditional clothing, and among women with dark skin pigmentation and poor dietary habits. Inadequate maternal vitamin D status in pregnancy is associated with poor fetal growth, impaired bone development and rickets in infants after birth. Furthermore, higher rates of preeclampsia and gestational diabetes are associated with low maternal vitamin D status during pregnancy. Toxicity of vitamin D is rare. Most countries recommend vitamin D supplementation during pregnancy but guidelines are controversial and inadequate compared to real mother’s and child’s needs. Wath’s the best strategy to follow and supplement mother during pregnancy? [less ▲]

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See detailCaractérisation phénotypique, morphologique et fonctionnelle des éosinophiles résidents du poumon
Raulier, Stéfanie ULiege

Doctoral thesis (2016)

Eosinophils have long been considered as destructive effector cells implicated in parasitic infections and allergic reactions such as asthma. This traditional restrictive view of eosinophils has now been ... [more ▼]

Eosinophils have long been considered as destructive effector cells implicated in parasitic infections and allergic reactions such as asthma. This traditional restrictive view of eosinophils has now been considerably extended. Indeed, beside their pro-inflammatory functions, eosinophils are also able to finely shape local innate and adaptative immune responses. Moreover, recent studies indicate that steady-state resident eosinophils are now thought to contribute to immune homeostasis at mucosal sites such as the gut. In the normal lung, resident eosinophils (rEOS) have been little-studied so far. Here, we report that in mice, steady-state pulmonary rEOS are parenchymal Siglec-Fint CD125int cells characterized by a ring-shaped nucleus. [less ▲]

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See detailLes itinéraires cliniques en support aux mesures transversales d’organisation des soins au patient : expérience de gestion de projet bottom-up
ERPICUM, Marie ULiege

Doctoral thesis (2016)

Our work contributes to the study of the health care organization’s evolution, by an integrating approach of clinical, research and teaching fields, in a bottom-up project management which aims ... [more ▼]

Our work contributes to the study of the health care organization’s evolution, by an integrating approach of clinical, research and teaching fields, in a bottom-up project management which aims integration of multidisciplinary and transversal care processes. From a research project was born a service project for the development of a blood management program in cardiac surgery. This project led to the development of a clinical pathway in cardiac surgery. The methodology of clinical pathways has been integrated in the new institutional strategic plan; the concept of “Care pathways” is developed to reinforce the implementation of "patient's pathway" and "Integrated Care" measures. This concept also finds an echo in the legislative and accreditation standards. Our researches and projects highlight the value of nurses for the integration of research and clinical care process. This approach is taught to Public Health Science Master’s students through educational missions in the Advanced Practice Nursing Science. [less ▲]

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See detailGestion des stupéfiants au bloc opératoire
LOMMEL, Isabelle ULiege

Master of advanced studies dissertation (2016)

La gestion des stupéfiants est une obligation légale. Dans le travail quotidien de l’infirmier de salle d’opération, la redondance d’écritures et le manque de disponibilités entrainent une banalisation de ... [more ▼]

La gestion des stupéfiants est une obligation légale. Dans le travail quotidien de l’infirmier de salle d’opération, la redondance d’écritures et le manque de disponibilités entrainent une banalisation de cette obligation. On oublie que ce médicament ‘différent’ est source de danger, d’addiction, de deal et qu’il peut être mortel. Ce travail est le résultat d’une analyse de la situation existante et de son adéquation avec la loi et la littérature scientifique. Sa conclusion permet de mettre en évidence que les participants au flux des stupéfiants doivent être conscientisés que leurs actions doivent être guidées par une logique. Cette logique de processus doit être institutionnelle. La philosophie Lean est d’application dans ce travail. Par la publication d’une synthèse des pistes de perfectionnement sous forme de délivrable ‘A3’, cette étude sera remise aux dirigeants du bloc opératoire Selon cette philosophie, il faut impérativement implémenter des méthodes de brainstorming consistant à mettre en évidence, entre collègues, les raisons de mal-fonctionnement. C’est également en équipe que des moyens d’amélioration de la situation doivent être élaborés, ce sans bouleversement majeur, c’est la méthode des petits pas. L’équipe du bloc doit mettre en place: 1. Un descriptif de la situation existante. 2. La pose en groupe d’indicateurs de bon fonctionnement. 3. L’étude collégiale de méthodes d’optimalisation des processus existants via des standards de travail. 4. Le suivi des indicateurs pour constater les améliorations et les amplifier par ajustement des processus. 5. Le bénéfice doit être visible tant au niveau de la sécurité du patient et du personnel que du stress ambiant. Cette philosophie doit perdurer dans le temps et s’intégrer dans le LEAN institutionnel. [less ▲]

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See detail« Analyse de l’implantation d’un protocole d’entraînement de la vitesse da ns une équipe de football »
Lombard, Gilles ULiege

Master's dissertation (2016)

L’organisation défensive des équipes de football et la densité des joueurs ont significativement augmenté depuis 40 ans (Wallace et Norton, 2014). Ceci influence les qualités physiques des joueurs qui se ... [more ▼]

L’organisation défensive des équipes de football et la densité des joueurs ont significativement augmenté depuis 40 ans (Wallace et Norton, 2014). Ceci influence les qualités physiques des joueurs qui se doivent d’être plus rapides pour faire la différence. Aujourd’hui, la filière anaérobie alactique, bien que minoritaire au niveau quantitatif (Mohr et al., 2003), est la déterminante principale de la performance sur le plan physique (Cometti et al., 2001). Etant donné l’importance de cette qualité physique, nous avons voulu examiner si l’introduction d’un travail spécifique de la vitesse durant 8 semaines aurait un impact significatif sur la performance fonctionnelle du joueur de football. Méthodologie L’échantillon de 18 joueurs est réparti dans des groupes contrôle et expérimental. Trois tests de terrain sont utilisés pour mesurer l’évolution du paramètre anaérobique avant et après le protocole de 8 semaines : un test de vitesse sur 10 mètres (Wilson et al., 1993), un test de zigzags sur 20 mètres (Little et Williams, 2005) et un counter movement jump avec les bras (Slinde et al., 2008). Durant 8 semaines, le groupe expérimental bénéficie, en plus de l’entraînement normal, de deux séances hebdomadaire de 30 minutes visant le développement de la vitesse. A la fin de l'étude, aucun résultat significatif n'a été trouvé que ce soit au niveau de la vitesse sur courte distance, en course brisée ou de la détente en squat jump et counter movement jump. [less ▲]

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See detailModel-Based Prediction of the Response to Vascular Filling Therapy
Pironet, Antoine ULiege

Doctoral thesis (2016)

Vascular filling is one of the most frequent interventions in intensive care units. Its expected effect is to increase cardiac output. However, this increase is only observed in approximately 50 % of ... [more ▼]

Vascular filling is one of the most frequent interventions in intensive care units. Its expected effect is to increase cardiac output. However, this increase is only observed in approximately 50 % of cases. In addition, excessive vascular filling can lead to deleterious effects, such as pulmonary oedema, which increase length of ventilation, stay, mortality and cost. Clinicians are thus looking for indices to provide a priori knowledge of the effect of vascular filling. This thesis focuses on a mathematical model-based approach to predict the response to vascular filling. Mathematical models are sets of equations representing the behaviour of a given system as, for instance, the cardiovascular system. To understand the concept of vascular filling, basic elements of cardio-vascular anatomy and physiology are presented in the first part of this thesis. Then, fur- ther details about vascular filling therapy are given, as well as the current indices used by clinicians to predict its effects. The static indices are easy to obtain, but do not perform well. The dynamic indices, based on cardio-pulmonary interac- tions, perform better, but are difficult and highly invasive to implement clinically. A new index, total stressed blood volume, also seems to perform well, but is not easy to obtain clinically. This work develops and then uses models of the cardio- vascular system to make this parameter available to clinicians. Building on the elements of physiology provided in the first part, the second part of this thesis describes ways to model the components of the cardio-vascular system as lumped elements, such as chambers, valves and resistances. Two mod- els of the cardio-vascular system, comprising respectively three and six cham- bers, are built from such elements. These two models involve a small number of parameters, including the total stressed volume in the model. The third part of this thesis describes the potential and methods to identify the parameters of the two cardio-vascular system models. Parameter identifica- tion aims at finding the parameter values that make model simulations as close as possible to measured data. The available data is thus first described, accord- ing to whether it is collected in an experimental laboratory or an intensive care unit. Then, it is mathematically demonstrated that all model parameters can the- oretically be identified from data available in an intensive care unit. However, practically speaking, some parameters are difficult to identify, because they have little influence on the simulations, or have the same effect as other parameters. Fi- nally, computational methods to perform parameter identification are presented and compared. The last part of this thesis presents two applications of the cardio-vascular system models to experimental data. First, all parameters of the six-chamber cardio-vascular system model are identified from data recorded during a preload reduction experiment. This result provides the first quantitative validation of the six-chamber model in transient conditions. Second, all parameters of the three-chamber cardio-vascular system model, including total stressed volume, are identified from data recorded during vascular filling experiments. The total stressed volume parameter is shown to be systematically related to the change in cardiac output after vascular filling. This last index thus provides, for the first time, a model-based means of predicting the response to vascular filling. [less ▲]

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See detailRégulation de la transcription du virus T-lymphotrope humain de type I (HTLV-1) par le complexe MiniChromosome Maintenance 2-7 (MCM2-7)
Barez, Pierre-Yves ULiege

Doctoral thesis (2016)

First oncogenic retrovirus discovered, the human T-lymphotropic virus type 1 (HTLV-1) infects approximately 5 to 10 millions of individuals worldwide. HTLV-1 is the etiological agent of adult T-cell ... [more ▼]

First oncogenic retrovirus discovered, the human T-lymphotropic virus type 1 (HTLV-1) infects approximately 5 to 10 millions of individuals worldwide. HTLV-1 is the etiological agent of adult T-cell leukemia and a neurodegenerative disorder called HAM/TSP (HTLV-1 associated myelopathy/Tropical spastic paraparesis). The HTLV-1 Tax protein interacts with the minichromosome maintenance MCM2-7 helicase, through the amino-terminal part of MCM3. This interaction accelerates firing of late DNA replication origins (ORI) in infected cells. Since Tax acts on the long terminal repeat (LTR), we hypothesized that the MCM2-7 complex could also be recruited to the viral promoter. Using chromatin immunoprecipitation, we show that MCM2-7 indeed interacts with LTR sequences. However, loading of the MCM complex does not fire DNA replication in an autonomous plasmid replication assay. In contrast, MCM2-7 activates viral transcription in luciferase reporter assays and in the context of a proviral clone. Short hairpin RNA interference of MCM2-7 inhibits LTR-driven Tax transactivation in lymphocytes. Finally, siRNAs targeting MCM3 reduce viral transcription in HTLV-1 infected cell lines. Together, our data thus indicate that the presence of the MCM2-7 complex on the HTLV-1 promoter is involved in viral transcription. [less ▲]

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See detailTherapy of Adult T-cell Leukemia by inhibition of the DNA repair mechanisms
Carpentier, Alexandre ULiege

Doctoral thesis (2016)

The Tax oncoprotein plays a central role in viral persistence and pathogenesis of human T-cell leukemia virus type 1 (HTLV-1). Indeed, Tax transforms primary cells and induces tumors in transgenic mouse ... [more ▼]

The Tax oncoprotein plays a central role in viral persistence and pathogenesis of human T-cell leukemia virus type 1 (HTLV-1). Indeed, Tax transforms primary cells and induces tumors in transgenic mouse models. Mechanistically, Tax accelerates the S phase of the cell cycle by firing late replication origins. This modification of the replication timing program induces an oncogenic stress that generates DNA damage such as double-strand breaks. Tax thus provides a selective advantage that promotes proliferation but also exposes host cells to potentially harmful clastogenic damage. How Tax-expressing cells handle this oncogenic stress is currently unknown. In this thesis, we show that Tax-expressing cells activate the DNA Damage Response (DDR). We quantified the repair efficiencies of DNA double-strand breaks. We demonstrate that Tax induces the recruitment of DNA repair core proteins (Ku70, RAD51 and RAD52) on chromatin. We further show that the efficiency of homologous recombination (HR) is inhibited by Tax. In contrast, non-homologous end joining (NHEJ) and single-strand annealing (SSA) are activated in the presence of Tax. Taking advantage of the addiction of Tax-expressing cells on improved DNA repair, we show that pharmacological inhibition of these pathways in HTLV-1 infected lymphocytes leads to an accumulation of DNA damage and apoptosis. We propose a novel therapeutic approach for the treatment of ATL based on the use of inhibitors targeting DNA repair pathways. [less ▲]

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See detailDEVELOPMENT OF PHARMACOLOGICAL TOOLS FOR THE IDENTIFICATION OF G PROTEIN-COUPLED RECEPTORS LIGANDS
Gilissen, Julie ULiege

Doctoral thesis (2016)

G protein-coupled receptors (GPCRs) represent the protein family most successfully targeted for treating human diseases. They couple to G proteins to mobilize second messenger pathways that lead to ... [more ▼]

G protein-coupled receptors (GPCRs) represent the protein family most successfully targeted for treating human diseases. They couple to G proteins to mobilize second messenger pathways that lead to cellular responses and ultimately to physiological changes. However many are poorly characterized with few ligands reported or remain completely orphans. Therefore, there is a growing need for screening-compatible and sensitive assays in order to identify new ligands. The present project aims at developing pharmacological tools to characterize the pharmacology and physiology of GPCRs. Our approach rely on i) development of receptor models and assays for the identification of ligands, ii) screening of chemical and virtual small molecules libraries and iii) analysis of structure-activity relationships study of active molecules. The project has been divided in two parts. To set-up assays for the evaluation of GPCRs activation, we selected the understudied succinate receptor 1 (SUCNR1) that is proposed to affect cellular metabolism and pathophysiology of diseases in multiple organs. Nevertheless the receptor has never been validated as a drug target because very few ligands have been described. So, developing pharmacological tools for SUCNR1 remains of great interest in therapeutic drug discovery. First, we have started by examining SUCNR1 signaling pathways in HEK293 cells. Our investigations have highlighted the efficient coupling to Gαi and thus the negative modulation of intracellular cAMP levels. Consequently we have implemented an assay sensitive to cAMP variations to identify ligands able to induce SUCNR1 activation. However, an important drawback to track agonists for Gαi-coupled receptors is the mandatory stimulation of cAMP levels. Inducers such as forskolin must be used and are sources of variations and errors. In order to avoid these artifacts we have set-up and validated a cAMP-inducer free method based on the GloSensor biosensor. This real time assay was amenable to high-throughput screening for the detection of Gαi-coupled receptors agonists. The strategy monitoring basal cAMP levels compared to the stimulated cAMP levels allowed to decrease recording time and artifcats from forskolin use, leading to the identification of fewer false positives and unidentified false negatives. Although both methods found agonists in the chemical library screened, no active new scaffolds on SUCNR1 were discovered. We infer that this method could facilitate the study and screening of Gαi-coupled receptors for active ligands. Secondly, given the interesting potential of SUCNR1 for promising therapeutic advances, we have carried out the study of the receptor interaction with its natural ligand, succinate. We have optimized the previous three-dimensional model for SUCNR1 binding pocket by means of more detailed structure-activity relationships study of succinate related molecules. The study of structure-activity relationships performed by Pierre Geubelle, in parallel to this work, allowed the deduction of the structural elements required to be active on SUCNR1. Thus we have defined a pharmacophore for activity on the receptor and subsequently evaluated various cycloalkanes. With our cAMP assay, Pierre Geubelle has highlighted the (1R, 2S)-1,2-cyclopropanedicarboxylate to be able to activate SUCNR1. We confirmed the activity of this compound on SUCNR1 capacity to recruit arrestin 3 and determined the pharmacological properties of this new ligand as SUCNR1 agonist, in vitro and in vivo. To confirm our in vitro results, we have also assessed the hypertensive properties of this cyclic analogue. Intravenous addition at the dose of 0.1 mg.kg-1 in rats has been demonstrated to increase blood pressure in the same range as succinate. Consequently we have demonstrated that (1R, 2S)-1,2-cyclopropanedicarboxylate could be regarded as an original synthetic full agonist for SUCNR1. In addition, the pharmacophore for SUCNR1 should help to generate synthetic compounds characterized by an increased potency and/or efficacy compared to succinate. [less ▲]

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See detailValidation of a Multiplex HPLC MS/MS assay for the measurement of steroid hormones
Rademaker, Gilles ULiege

Master's dissertation (2016)

Facing an improvement of the quality assurance in all the laboratory, the validation of methods has become a step that cannot be got round. The objective of this work is the validation of a Protein ... [more ▼]

Facing an improvement of the quality assurance in all the laboratory, the validation of methods has become a step that cannot be got round. The objective of this work is the validation of a Protein-Precipitation HPLC-MS/MS method for the measurement of steroid hormones (Aldosterone, Androstenedione, Cortisol, 17-OH Progesterone, DHEAS and Testosterone). To achieve this purpose, a precision, recovery, linearity, carry over assay and a limit of quantification are performed. After collection of the data, results are calculated and statistically analysed. They allow to set boundaries to the method and to understand more easily how we could improve it. The results show that the method is effective for all hormones except the aldosterone, for which the method still has to be improved. Moreover, a comparison of the analysis of the testosterone between Cobas and HPLC MS/MS is made. In the lab, this hormone is analysed with Cobas but a transition to the HPLC MS/MS can be done because the results are satisfactory. [less ▲]

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See detailInfluence du tabagisme sur la santé parodontale
SALHI, Leila ULiege

Master of advanced studies dissertation (2016)

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See detailMise au point d'un biomatériau à base de chitosan pour le traitement de l'arthrose
Oprenyeszk, Frédéric ULiege

Doctoral thesis (2015)

L'arthrose est une pathologie dont la prévalence est élevée avec un retentissement socioéconomique important. À ce jour, les traitements de l’arthrose sont essentiellement symptomatiques. Le remplacement ... [more ▼]

L'arthrose est une pathologie dont la prévalence est élevée avec un retentissement socioéconomique important. À ce jour, les traitements de l’arthrose sont essentiellement symptomatiques. Le remplacement de l'articulation arthrosique par une prothèse est réservé aux formes les plus évoluées de la maladie. Dans ce contexte, il existe un réel besoin de nouveaux traitements bien tolérés et capables de prévenir ou de retarder la progression de la maladie. Dans ce but, nous avons développé des nouveaux biomatériaux sous la forme de billes ou d'hydrogel composés de chitosan d'origine non animale. Dans la première partie de ce travail, nous avons étudié in vitro le comportement des chondrocytes humains, provenant de cartilage arthrosique, incorporés dans des billes de chitosanalginate. Nous avons mesuré la quantité de médiateurs pro-infl ammatoires, cataboliques et anaboliques produite par les chondrocytes. Dans la deuxième partie, nous avons étudié les effets des billes de chitosan-alginate, injectées dans l’articulation, sur la progression de l’arthrose induite chez le lapin par section du ligament croisé antérieur. In vitro, nous avons mis en évidence les effets bénéfi ques et prometteurs des billes de chitosanalginate sur le métabolisme des chondrocytes humains arthrosiques. Dans ces conditions, ils produisaient moins de médiateurs infl ammatoires et cataboliques tout en maintenant la synthèse de composants spécifi ques de la matrice du cartilage. L'étude chez le lapin a montré que l’injection des billes de chitosan-alginate dispersées dans un hydrogel de chitosan prévenait le pincement de l’interligne articulaire - évalué sur une radiographie standard - et réduisait de façon signifi cative la gravité des lésions histologiques du cartilage ainsi que la synovite. En conclusion, la bille de chitosan-alginate est une matrice intéressante pour la thérapie cellulaire des lésions du cartilage et représente une alternative à l’acide hyaluronique pour la viscosupplémentation. [less ▲]

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See detailL'estétrol et le développement tumoral
Gallez, Anne ULiege

Master's dissertation (2015)

A l’heure actuelle, le risque augmenté de troubles thromboemboliques et de cancer du sein chez les femmes sous hormonothérapie est un problème majeur de santé publique. La découverte de nouvelles ... [more ▼]

A l’heure actuelle, le risque augmenté de troubles thromboemboliques et de cancer du sein chez les femmes sous hormonothérapie est un problème majeur de santé publique. La découverte de nouvelles molécules procurant une sécurité sanitaire accrue aux utilisatrices est donc nécessaire. L’estétrol (E4) est proposé comme candidat potentiel. L’E4 est une hormone stéroïdienne, de type « œstrogène », retrouvée naturellement chez l’humain et synthétisée uniquement par le foie fœtal durant la grossesse. Sa grande biodisponibilité orale et son temps de demi-vie de 28 heures chez l’humain le rendent intéressant en tant qu’hormonothérapie de substitution (ERT/HRT). L’E4 est capable de traiter efficacement les symptômes principaux de la ménopause (les bouffées de chaleur, l’atrophie vaginale et l’ostéoporose) et ce, dès une concentration de 0,3 mg/kg/jour. L’étude de son impact sur le cancer du sein est au centre de ce mémoire, puisque c’est l’une des conséquences majeures de l’utilisation prolongée d’œstrogènes et que les données de la littérature restent controversées Des résultats préliminaires obtenus au laboratoire ont montré que l’E4 (3 mg/kg/jour) augmentait le poids des tumeurs dans le modèle murin de carcinogenèse mammaire MMTV-PyMT, contrairement à l’ovariectomie et au traitement au Tamoxifène. Au terme de ce mémoire, nos recherches démontrent que l’E4 utilisé aux doses 0,3 et 7 mg/kg/jour n’influence pas significativement la croissance tumorale. Par contre, l’E4 à 3 mg/kg/jour majore le poids tumoral et la dissémination métastatique chez des animaux ovariectomisés et intacts. De plus, l’E4 délivré à 3 mg/kg/jour est capable d’augmenter l’angiogenèse et de diminuer la nécrose et l’hypoxie intra-tumorale, de manière similaire à l’oestradiol (E2) alors que la dose de 0,3mg/kg/jour n’est pas suffisante pour observer cet effet. En conclusion, les travaux menés pendant mon mémoire de Master ont permis de caractériser les effets de l’E4 sur la carcinogenèse mammaire hormonodépendante, la dissémination métastatique et l'angiogenèse tumorale. Au vu de nos résultats, nous ne pensons pas qu'il soit judicieux d'utiliser l'E4 comme traitement anti-tumoral, comme cela a été suggéré par certains auteurs. Au contraire, nos données suggèrent que pour éviter un effet de l’E4 sur la croissance tumorale et l’angiogenèse, il est nécessaire de privilégier le développement d’un traitement clinique de la ménopause avec de faibles concentrations d’E4. [less ▲]

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See detailGestion du risque associé au cycle de vie des méthodes analytiques : Applications aux molécules de faibles poids moléculaires analysées par Spectrométrie de Masse
Hubert, Cédric ULiege

Doctoral thesis (2015)

Analytical method lifecycle is composed of several steps, but always starts with a question defining the problem. Analytical method performances are consequently specified by the analyst trough the ... [more ▼]

Analytical method lifecycle is composed of several steps, but always starts with a question defining the problem. Analytical method performances are consequently specified by the analyst trough the definition of the “Analytical Target Profile (ATP)”, as proposed by the regulatory bodies. Subsequent steps (namely the development and validation steps) then take place, followed by routine use of the analytical procedure. In the specific context of the pharmaceutical industry, regulatory authorities have recently imposed the assessment and management of risk throughout the entire product lifecycle. This includes the analytical procedure and consequently its own lifecycle. Working in this context, our concerns were initially focused on the validation step of the method lifecycle. Indeed, the objective of analytical method validation is to demonstrate that this method is suited for quantifying the target analytes with an established and suitable level of accuracy, as defined by the “ATP”. This is sometimes called the “fit-for-future-purpose” concept. In the course of this study we have experimentally confirmed that a decision regarding the validity of a method based on prediction can be achieved by using the “β-expectation tolerance interval” (accuracy profile) as a decision tool. Indeed, it seemed essential to demonstrate the capability of this approach to manage a part of the analytical risk before addressing the development step. Typically this step of the analytical procedure lifecycle is addressed using a “Changing One Separate Factor a Time (COST)” approach (also known as the “Quality-by-Testing (QbT)” approach). By means of a complex case study, and considering validation of the method through the accuracy profile, we have shown that this strategy can lead to a suitable method for assessing the risk of routine use, even where the experimental domain is not examined. In order to consider an experimental domain rather than a set of specific experimental conditions during the development phase, we have evaluated a multivariate approach: the “Quality-by-Design (QbD)” strategy. This strategy allows the definition of a “Design Space (DS)” by means of design of experiments (DoE). This DS, computed considering critical method parameters, allows the analyst to focus on the main objective of an analytical method: obtaining reliable results using a robust method. A comparative study of the QbT versus QbD approach was performed. In the course of this study, the benefits of the QbD strategy in terms of managing the qualitative part of the analytical risk were highlighted. Finally, we have focused our research on the development of a global strategy allowing the unification of the development and validation phases in a single step. With this innovative approach, we are the first to propose a strategy allowing the management of global analytical risk (i.e., both qualitative and quantitative risk). Indeed, we have demonstrated that it is possible to validate an experimental domain by means of the accuracy profile. With this innovative strategy, the DS is no longer simply the place where qualitative performances are obtained, but also the space where quantitative performances of the analytical procedure are assessed and managed. In conclusion, during this thesis, we have confirmed the predictive capabilities of the accuracy profile. Moreover, we have highlighted the benefits of a QbD strategy in terms of risk management. We have also demonstrated that this methodology can be used as a learning tool, facilitating the continuous improvement of the analytical procedure. Furthermore, with the innovative strategy presented during the latter part of this work, we have demonstrated that qualitative and quantitative risk can be assessed and managed throughout the entire analytical method lifecycle. [less ▲]

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See detailEtude de la reconstitution immunitaire après greffe de cellules souches hématopoïétiques : focus sur la fonction thymique et les lymphocytes T régulateurs
HANNON, Muriel ULiege

Doctoral thesis (2015)

L’allogre e de cellules souches hématopoïétiques, après conditionnement myéloalbatif ou non, est devenue une option de choix dans le traitement des maladies hématologiques malignes ou génétiques ... [more ▼]

L’allogre e de cellules souches hématopoïétiques, après conditionnement myéloalbatif ou non, est devenue une option de choix dans le traitement des maladies hématologiques malignes ou génétiques. Malheureusement le succès de ce traitement se trouve trop souvent entaché par des complications majeures telles que les infections ou la maladie du greffon contre l’hôte (GVHD), dans laquelle les cellules du donneur attaquent l’organisme du receveur. La reconstitution d’un système immunitaire fonctionnel, notamment via le thymus, est une étape clef dans la résolution de ces deux complications et l’utilisation de lymphocytes T régulateurs semble très prometteuse dans la lutte contre la GVHD. Le présent travail vise donc à étudier la reconstitution du système immunitaire après allogreffe sous trois angles différents, en nous focalisant sur la fonction thymique et l’influence des lymphocytes T régulateurs (Treg). Dans la première partie, nous évaluons la reconstitution immunitaire à long terme après greffe non-myéloablative et montrons que la néo-génération de lymphocytes T par le thymus s’effectue à partir du jour 100 chez les patients de moins de 60 ans alors qu’au delà de cet âge, elle est quasiment absente. Nous établissons également que la GVHD chronique (cGVHD) sévère possède des effets extrêmement délétères sur le thymus. Étant donné l’impact de la cGVHD sur le thymus et la reconstitution immunitaire, nous avons voulu comparer l’impact, sur ces deux paramètres, d’un conditionnement nonmyéloalbatif censé réduire la GVHD et composé d’une irradiation lymphoïde totale et d’anticorps anti-thymocytes (TLI-ATG) par rapport au conditionnement classique consistant en une irradiation corporelle totale associée à de la fludarabine (TBI-Flu). Il ressort de cette étude que, bien que réduisant de manière significative l’incidence de cGVHD, le conditionnement TLI-ATG altère fortement la reconstitution du système immunitaire et impacte négativement le taux de rechute/progression chez les patients traités. Enfin, toujours dans le but de réduire le taux de GVHD post-greffe, nous avons choisi d’examiner l’impact des Treg comme traitement de la xGVHD. Dans ce but, nous montrons qu’une sélection de Treg humains, sur CliniMACS par déplétion CD8/19 et sélection CD25, fournit une population de cellules enrichies en Treg capable de retarder de manière statistiquement significative l’apparition d’une GVHD xénogénique induite par injection de PBMC humains (autologues aux Treg) dans un modèle pré-clinique chez la souris NSG. De plus, lorsque injectée sans les PBMC, cette population enrichie n’induit pas par elle-même de GHVD. [less ▲]

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See detailImaging the mechanisms involved in abdominal aortic aneurysms rupture; a step towards patient-specific risk assessment
NCHIMI LONGANG, Alain ULiege

Doctoral thesis (2015)

Introduction The general context of this dissertation is to evaluate patient-specifi c approaches to the risk of rupture of abdominal aortic aneurysm (AAA), using imaging techniques with ability to assess ... [more ▼]

Introduction The general context of this dissertation is to evaluate patient-specifi c approaches to the risk of rupture of abdominal aortic aneurysm (AAA), using imaging techniques with ability to assess biological processes. Following a thorough description of available imaging techniques, our work is divided in two main research objectives, namely: (i) to provide greater clinical value to existing but unproven imaging concepts, and (ii) to suggest new concepts for improved AAA risk of rupture assessment. Methods The fi rst research objective evaluated how far imaging biological activities using 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) and modeling wall stress using fi nite element simulations (FES) may help clinical decisionmaking in patients with AAA, and what would be their incremental value as compared to diameter-based patient management algorithms. On a patient basis, clinical outcomes were evaluated with regard to FDG PET and FES signaling. Further, the concept of AAA risk-equivalent diameter using FES was described and retrospectively validated using data from large multicenter trials. The second research objective included the assessment of the biological activities of the intraluminal thrombus (ILT) and the demonstration of its deleterious role in AAA using multimodality imaging. A special emphasis was put on the ability of magnetic resonance imaging (MRI) to monitor the biological activities of ILT without exogenous contrast, by evaluating its iron content. Results Increased FDG uptake was a diameter-independent marker of AAA-related events over 2 years. Missing dichotomy prevented such a fi nding for increased wall stress, although its correlation with increased FDG uptake indicates a potentially comparable value in terms of risk management. Wall metabolism is infl uenced by patient-specifi c susceptibility factors, indicating hereditary or acquired alteration of the biological responses to wall stress. The concept of risk-equivalent diameters on FES links biomechanical estimates to basic conclusions drawn from large diameter-based clinical AAA trials. Our retrospective and diameter-adjusted validation analysis verifi ed that biomechanical risk indicators are higher in ruptured than non-ruptured AAAs. Part of the FDG uptake is associated with biological activity along the luminal surface of the ILT, where we experimentally demonstrated phagocytosis of superparamagnetic iron oxide on MRI , both ex vivo and in vivo. This phagocytosis is correlated with the abundance of leukocytes and proteolytic activity. In addition, unenhanced MRI appearances resulting from the endogenous iron distribution within ILT also relate to these biological activities. Lastly, multimodality imaging was used to confi rm the concept of the deleterious role of the ILT in AAA growth in a model of AAA by infusion of elastase in the rat. Conclusion MRI and FDG PET are capable of evidencing and quantifying in vivo some of the notoriously deleterious biological processes taking place in the aneurysmal sac, especially related to the entrapped phagocytes and red blood cells in ILT and the periadventitial infl ammatory response. The central role played by ILT and its biological activities was demonstrated in vivo using several imaging techniques. The clinical value of imaging these biological activities is epitomized by a diameterindependent 2-year increased risk of event in AAA with increased wall metabolism. [less ▲]

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See detailDiagnosis and clinical interest of asthma inflammatory phenotypes
SCHLEICH, FLorence ULiege

Doctoral thesis (2014)

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See detailLes généralistes, la prévention et la promotion de la santé. Etat des lieux, attitudes actuelles et voies d’avenir
Vanmeerbeek, Marc ULiege

Doctoral thesis (2014)

The aim of this work was to identify ways to apply preventive health services provided by general practitioners to health improvement, rather than case-by-case improvements of biomedical markers. Health ... [more ▼]

The aim of this work was to identify ways to apply preventive health services provided by general practitioners to health improvement, rather than case-by-case improvements of biomedical markers. Health was considered within its bio-psycho-social definition, and equity in health had to be maintained or improved in this process. Research questions: • What are general practitioners (GPs)’ representations of their role and actions in the Belgian preventive framework? (Chapter 2); • What factors can predict GPs’ involvement to a greater or lesser degree in this topic? (Chapter 3); • What are the published operating models about preventive health care and health promotion in primary care that can be used to formulate working hypotheses for the improvement of preventive clinical practice? (Chapter 4). • How to improve the connection between preventive health services, health promotion and the curative approach? (Chapter 5). Four studies are presented that illustrate the topic, as they were published (or under publication). Among the definitions of health, the weight of the structural determinants and the socio-economic context on health levels was stressed, while the weight of the health systems was gradually reduced to a lesser role. But patient education is still expected to help control the individual determinants of health. Primary care and general practice are adequately fit to a tailored approach of large populations. However, the physicians’ vocational training does not address integration of health promotion and curative practice. Meeting field GPs through individual semi-structured interviews allowed for a dialog that explored various aspects of the preventive health services delivery. Predisposing factors closely linked to the physicians’ personality appeared to be determinants. Organisational limitations and difficulties, and almost non-existent collective visions of the practice population were highlighted. To understand what shapes the behaviour of GPs in preventive healthcare delivery beyond statements, an attitude scale was devised. The analysis allowed the statements to be sorted into a four-factor model consisting of performance appraisal, guideline adherence, patient-centeredness & collaboration, and power sharing. The GPs’ attitudes towards preventative service delivery increased with multidisciplinary practice and decreased with seniority in the profession. A narrative literature review retrieved twelve models that address preventive health care and health promotion in primary care; these models helped formulate working hypotheses for the improvement the current situation. The models progressively integrated elements from the health promotion charters of the World Health Organisation and from the Commission on Social Determinants of Health. The following elements valued by health promotion could be integrated to preventive healthcare: empowerment of citizens, addressing community environment; increased involvement in local health professionals’ networks; and the integration of individual and collective approaches within the same health care facilities to simultaneously address individual customisation, efficiency and equity objectives. There was little room for patients in elaborating the models. Do GPs have the opportunity to develop the partnerships that are required to move to health promotion as proposed by these models? The trend toward quality assurance systems among health systems can contribute to the setting of structures and operating modes that are necessary. The quality cycle could be one of the tools used for that purpose. The quality criteria of primary care lead the way to a framework for integrating preventive health care and health promotion. • Comprehensive care addresses the bio-psycho-social environment of patients, considering patients as partners during the health care process. • Continuity of care challenges the managing of clinical data between members of a care team, thereby enhancing quality of care, patient safety and equity. • Integrated care involving caregivers and health promotion professionals will require adaptation of job description reference lists. The challenge created by these three quality criteria entails changes in GPs vocational training and necessitates a new definition of their specific tasks and skills. Such a challenge requires collaborative teamwork of the five members of Boelen’s “partnership pentagon”. The social accountability of medical schools should be fostered. [less ▲]

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See detailApplication de la diffusion Raman exaltée de surface à la détection de petites molécules d'intérêt : le lactate
Dumont, Elodie ULiege

Master's dissertation (2014)

Surface-enhanced Raman spectroscopy, much more sensitive than normal Raman spectroscopy, was chosen as a « Green Chemistry » analytical tool to develop a quantitative approach for sodium lactate at ... [more ▼]

Surface-enhanced Raman spectroscopy, much more sensitive than normal Raman spectroscopy, was chosen as a « Green Chemistry » analytical tool to develop a quantitative approach for sodium lactate at physiological concentrations detection. Indeed, the lactate is an important biomarker involved in many diseases, including Age-Related Macular Degeneration. Different nanoparticles’ synthesis were performed and characterized to ensure their repetability. These nanoparticles were then put into contact with lactate in order to detect this metabolite with a good sensitivity. The next step was the functionalization of the nanoparticles’ surface with the aim of increasing sensitivity and selectivity of the detection. Among the capping agents tested, (11-mercaptoundécyl)-N,N,N-triméthylammonium bromide, a quaternary ammonium compound, was selected and the experimental conditions were optimized with the help of a design of experiments. Once again, lactate quantification was performed. Detection was possible from 0,1 to 7,5 mM. Finally, detection of dried spots of lactate in water and in phosphate buffer was possible through the same functionalization agent. [less ▲]

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See detailIntraocular lenses with functionalized surfaces by biomolecules in relation with lens epithelial cell adhesion
Huang, Yi-Shiang ULiege

Doctoral thesis (2014)

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed onto the implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LEC) undergoing Epithelial ... [more ▼]

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed onto the implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LEC) undergoing Epithelial-Mesenchymal Transition (EMT). Literature has shown that the incidence of PCO is multifactorial including patient’s age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs show the former has more severe PCO after EMT transition. Additionally, the LEC adhesion is favored onto the hydrophobic materials compared to the hydrophilic ones. A biomimetic strategy to promote LEC adhesion without de-differentiation to reduce PCO development risk is proposed. RGD peptides, as well as their grafting and quantification methods on a hydrophilic acrylic polymer were investigated. The surface functionalized IOL promoting LEC adhesion via integrin receptors can be used to reconstitute the capsule-LEC-IOL sandwich structure, which is considered to prevent PCO formation in literature. The results show the innovative biomaterial improves LEC adhesion, and also exhibits similar optical (light transmittance, optical bench) and mechanical (haptic compression force, IOL injection force) properties comparing to the starting material. In addition, comparing to the hydrophobic IOL material, this bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression. The in vitro assays suggest this biomaterial has the potential to reduce some risk factors of PCO development. [less ▲]

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See detailEtude multiparamétrique de polymères acryliques, modèles de lentilles intraoculaires : recherche d'indicateurs de risque de développement de la cataracte secondaire.
Bertrand, Virginie ULiege

Doctoral thesis (2014)

In this study we compared 3 biomaterials (supplied by the firm PhysIOL , Science park, Liège, Belgium). We have at first to estimate certain physico-chemical properties such as the surface hydrophilicity ... [more ▼]

In this study we compared 3 biomaterials (supplied by the firm PhysIOL , Science park, Liège, Belgium). We have at first to estimate certain physico-chemical properties such as the surface hydrophilicity, the adhesion force (Atomic Force Microscopy). We were then interested in the bioadhesive character of these biomaterials by estimating in vitro, the adsorption of BSA and the cellular adhesion (lens epithelial cells, LECs), the ex vivo capsular adhesion and the in vivo tissular reaction (subcutaneous implant of polymers for 1 month (rabbit)). We then realized a proteomic analysis using mass spectrometry : LECs used during our in vitro tests, proteins adsorbed on biomaterials after incubation in a complex medium, the fibrous capsule surrounding the biomaterial after its subcutaneous implantation and the lens (MALDI imaging). [less ▲]

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See detailContribution à l’étude du Plasma Riche en Plaquettes (PRP) dans le traitement des lésions tendineuses
Kaux, Jean-François ULiege

Doctoral thesis (2014)

Platelet-rich plasma (PRP) may represent a new therapeutic option for chronic tendinopathies. Platelets release various cytokines and growth factors which promote angiogenesis, tissue remodeling, and ... [more ▼]

Platelet-rich plasma (PRP) may represent a new therapeutic option for chronic tendinopathies. Platelets release various cytokines and growth factors which promote angiogenesis, tissue remodeling, and wound healing. We made an extended literature review of the use of PRP in chronic tendinopathies. Despite the proven efficacy of PRP on tissue regeneration in experimental studies, there is currently scanty tangible clinical evidence with respect to its efficacy in chronic tendon disorders. The few studies that have been performed appear unlikely to be comparable. Randomized controlled studies with appropriate placebo groups are needed to determine the real effectiveness of PRP for treating chronic musculoskeletal injuries. After, we made a study to compare the platelet concentrations using 5 techniques of preparation of PRP and observed that each provides a very different PRP, with variations in the platelet concentrations and of the amount (if any) of erythrocytes and leucocytes. White blood cells could adversely affect wound healing through the release of proinflammatory factors responsible for extracellular matrix degradation. In addition, erythrocyte lysis releases free radicals that harm tissue structures. We thus think that ideal PRP should not contain any erythrocytes or leucocytes, and that the quality of the PRP could perhaps partially explain the variable results observed in the literature. The aim of our next study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. We concluded that an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance. Vascular endothelial growth factor (VEGF) is a platelet growth factor known to regulate angiogenesis. VEGF-111, a biologically active and proteolysis-resistant splice variant of this family, was recently identified. We made a study with the aim of evaluating whether VEGF-111 could have a therapeutic interest in tendon pathologies with the same rat protocol as our previous study. The force necessary to induce tendon rupture was greater for tendons of the VEGF-111 group (but less than the results obtained with the PRP in our previous study), while the section areas of the tendons were similar. The mechanical stress was similar at 5 and 15 days in both groups but was improved for the VEGF-111 group at day 30. No differences were observed in the mRNA expression of collagen III, tenomodulin and MMP-9. Finally, we made a study, the aim of which was to evaluate the clinical status and the return to sports activities in patients with chronic upper patellar tendinopathies, up to one year after a single infiltration of PRP. Twenty patients with chronic upper patellar tendinopathy were enrolled. Assessments were made before infiltration of PRP, and 6 weeks, 3 months and 1 year after the infiltration, using a 10-point Visual Analogic Scale, clinical examinations with a pressure algometer, algofunctional scores (IKDC and VISA-P), functional assessments (isokinetic and optojump evaluations) and imagery (ultrasounds and MRI). The PRP was obtained with an apheresis system (COM.TEC, Fresenius). Six millilitres of PRP were injected without local anaesthetic. One week after infiltration, patients started a standardised sub-maximal eccentric reeducation. We observed that with time, during the 1-year follow-up, VAS dropped significantly and both IKDC and VISA-P scores improved also significantly. During functional evaluation, it decreased as well, but without significant functional improvement. No improvements in the imagery measurements were observed. Younger patients seemed to be more susceptible to have a relief of pain by the PRP infiltration. Seventy percent of the patients reported a favourable evolution with decrease of pain, 15% reported no improvement and 15% were treated surgically. Seventy percent returned to sports activities, 64,3% without any pain and 50% recovered the same sports level. Even if 1 infiltration seems to be efficient in the indication of patellar tendinopathies, most studies evaluated the effects of 3 successive infiltrations. However, the multiplication of infiltrations risks increasing complications, and this treatment can be expensive. It seemed relevant to evaluate if 2 infiltrations of PRP would be more effective than only 1.Twenty patients suffering from jumper’s knee for more than 3 months were enrolled and randomized in 2 groups (1 or 2 infiltrations of PRP). The follow-up was made as follows: VAS, IKDC and VISA-P scores, algometer, isokinetic and ultrasounds evaluations. The concentration of the PRP used for each infiltration was similar in both groups, without any red or white blood cells. Results for all the evaluations did not show any difference between the groups. The comparison of 1 or 2 infiltrations of PRP did not show any difference between the 2 groups after a follow-up of 3 months. A second close infiltration of PRP to treat upper patellar tendinopathies is not necessary to improve the efficacy of this treatment in the short term. However, these results must be evaluated at a longer term. [less ▲]

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See detailAltérations fonctionnelles des cellules dendritiques dans la cancérisation du col utérin
Demoulin, Stéphanie ULiege

Doctoral thesis (2014)

Le cancer du col utérin (SCC) est presque universellement associé à une infection par des papillomavirus à haut risque (HR-HPV) et est une des principales causes de décès par cancer chez les femmes à ... [more ▼]

Le cancer du col utérin (SCC) est presque universellement associé à une infection par des papillomavirus à haut risque (HR-HPV) et est une des principales causes de décès par cancer chez les femmes à travers le monde. Actuellement, deux vaccins empêchant l'infection par des HR-HPV spécifiques sont disponibles, cependant, ils n'ont pas d'efficacité thérapeutique et il a été estimé qu'il n'y aura pas de baisse mesurable des cancers associés à HPV avant 2040. Même si l'infection par les HR-HPV est nécessaire à la carcinogenèse du col utérin, elle n'est pas suffisante pour le développement du cancer puisque seule une minorité des cas progresseront vers une tumeur. En effet, d’autres facteurs, liés à l’hôte ou environnementaux, qui agissent après l’infection peuvent augmenter le risque de développement cancéreux. Récemment, il a été proposé que les cellules épithéliales et/ou inflammatoires pourraient créer un environnement immunosuppresseur facilitant la transformation maligne en altérant l'immunité antitumorale. Etant donné que plusieurs études ont montré que le microenvironnement tumoral pouvait altérer la fonction des cellules dendritiques plasmacytoïdes (pDC) et conventionnelles (cDC) et les rendre tolérogènes, nous avons concentré notre attention sur ces cellules et sur leur rôle potentiel dans la cancérisation du col utérin. Dans la première partie de ce travail, nous nous sommes concentrés sur l'implication des pDC dans la cancérisation du col utérin. Nous avons d'abord montré que ces cellules sont recrutées au cours de la séquence "métaplasie-dysplasie-cancer" du col de l’utérus suite à l’augmentation de l'expression de la chémérine dans ces lésions. Etant donné que les pDC représentent un population cellulaire rare dans le sang périphérique, nous avons développé une nouvelle méthode afin de générer un grand nombre de pDC à partir d'un nombre limité de cellules progénitrices CD34+ isolées de sang de cordon ombilical. Notre but était de fournir un outil permettant de définir si la fonction de ces cellules peut être influencée par le microenvironnement tumoral. Les pDC générées in vitro présentent la morphologie, les caractéristiques phénotypiques et fonctionnelles des pDC se trouvant dans le sang périphérique. Les pDC générées in vitro ont été exposées aux molécules sécrétées dans le microenvironnement du cancer du col utérin grâce à un système de coculture. Ces pDC présentent un profil de maturation altéré, une diminution de sécrétion en IFN-α, une cytokine ayant un rôle antiviral et antitumoral. De plus, ces pDC sont capables d’induire la différenciation des lymphocytes T CD4+ naïfs en cellules T régulatrices (Treg) grâce à l’expression d’ICOSL. Les cellules Treg et les pDC forment des clusters autour des cellules cancéreuses, ce qui facilite leurs interactions. Nous avons identifié HMGB1 comme étant la molécule impliquée dans la modification du phénotype et de la fonction des pDC exposées au microenvironnement du col utérin. En parallèle, nous avons démontré que les cDC différenciées en présence de lignées de SCC du col utérin acquièrent un phénotype semi-mature et une activité fonctionnelle défectueuse, associée à une augmentation de leur sécrétion d'IL-10, une cytokine immunosuppressive. En outre, les cDC présentent également une fonction tolérogène associée à leur expression d’ILT3. L’inhibition de la voie de signalisation RANK/RANKL a permis de limiter l’effet des lignées de SCC sur les cDC. Ainsi, le cancer du col de l’utérus exploite activement la plasticité des pDC et des cDC afin de promouvoir sa progression. Des traitements ciblant HMGB1 et RANKL pourraient être utilisés afin de restaurer les activités anti-tumorales des cellules dendritiques et, par conséquent, de surmonter la tolérance immunitaire associée au microenvironnement du cancer du col utérin. [less ▲]

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See detailL’HYPOGONADISME HYPOGONADOTROPE NORMOSMIQUE ISOLE (HHnI)
VALDES SOCIN, Hernan Gonzalo ULiege

Master of advanced studies dissertation (2014)

L'hypogonadisme hypogonaodotrope isolé est une maladie génétique qui peut se produire avec un sens normal de l’olfaction ou en association avec une anosmie/hyposmie (syndrome de Kallmann.) L’hypogonadisme ... [more ▼]

L'hypogonadisme hypogonaodotrope isolé est une maladie génétique qui peut se produire avec un sens normal de l’olfaction ou en association avec une anosmie/hyposmie (syndrome de Kallmann.) L’hypogonadisme hypogonadotrophique peut aussi se décliner associé à d’autres traits distinctifs syndromiques, tel que le Prader Willy, que nous ne traiterons pas ici. Dans ce mémoire, nous nous concentrerons sur l’hypogonadisme hypogonadique central normosmique, qui d’un point de vue épidémiologique est plus fréquent chez l’homme. [less ▲]

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See detailCaractéristiques Cliniques Et Impact Du Syndrome De Smith-Magenis : Étude d’une série de 47 patients
JACQUINET, Adeline ULiege

Master's dissertation (2014)

Le syndrome de Smith-Magenis est un syndrome délétionnel récurrent caractérisé par l’association de traits dysmorphiques, de troubles du comportement et de troubles du sommeil. Une déficience ... [more ▼]

Le syndrome de Smith-Magenis est un syndrome délétionnel récurrent caractérisé par l’association de traits dysmorphiques, de troubles du comportement et de troubles du sommeil. Une déficience intellectuelle de sévérité variable est fréquente mais non systématique. Il implique une prise en charge médicale multidisciplinaire du fait des possibles malformations associées, essentiellement cardiaques et rénales, et des éventuelles complications (scoliose, problèmes ORL, anomalies ophtalmologiques, problèmes dentaires, métaboliques et endocriniens). Dans cette étude rétrospective, nous reprenons et discutons les caractéristiques cliniques et diagnostiques d’une cohorte de 47 patients ainsi que les répercussions du syndrome en termes d’impact familial, de prise en charge et de scolarité. [less ▲]

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See detailRole of adipose tissue inflammation and NLRP3 inflammasome in the pathogenesis of metabolic syndrome and type 2 diabetes.
Esser, Nathalie ULiege

Doctoral thesis (2014)

It is recognized that a chronic low-grade inflammation and an activation of the immune system are involved in the pathogenesis of type 2 diabetes. Systemic inflammatory markers are risk factors for the ... [more ▼]

It is recognized that a chronic low-grade inflammation and an activation of the immune system are involved in the pathogenesis of type 2 diabetes. Systemic inflammatory markers are risk factors for the development of type 2 diabetes and its macrovascular complications. Adipose tissue, liver, skeletal muscle and pancreas are themselves sites of inflammation in obesity. An infiltration of macrophages and other immune cells is observed in these tissues, associated with a cell population shift from an anti-inflammatory to a pro-inflammatory profile. These cells are crucial for the production of pro-inflammatory cytokines, which act in an autocrine and paracrine manner to interfere with insulin signaling in peripheral tissues or induce β-cell dysfunction and subsequent insulin deficiency. Particularly, the pro-inflammatory cytokine interleukin-1 beta (IL-1β) is involved in the pathogenesis of type 2 diabetes through the activation of the NLRP3 inflammasome. Obesity is a heterogeneous disease; some patients are obese but metabolically healthy (MHO) whereas others develop metabolic disorders (metabolically unhealthy or MUO). Adipose tissue is also heterogeneous; its visceral component is more associated with metabolic disorders than its subcutaneous component. The aim of this work is to assess whether differences in NLRP3 inflammasome activity and adipose cell composition play a role in such phenotypic and biochemical heterogeneities. MHO and MUO phenotypes were defined, respectively, as the absence and the presence of metabolic syndrome. Cellular composition and intrinsic inflammasome activity were investigated by flow cytometry, quantitative RT-PCR, ELISA and tissue culture studies in paired subcutaneous and visceral adipose tissues from 23 MUO, 21 MHO and 9 lean individuals. Relevant and significant differences were found among the three study groups, including increased secretion of IL-1β, increased expression of IL1B and NLRP3 mRNA, increased levels of adipose tissue macrophages and granulocytes, and decreased levels of regulatory T lymphocytes in the visceral adipose tissue of MUO patients compared with that of MHO and lean participants. Both caspase-1 activity and IL-1β release were higher in the macrophages derived from the visceral adipose tissue of MUO compared with MHO. Similar significant differences were showed between the subcutaneous and the visceral adipose tissues of the MUO subjects. In conclusion, the MUO phenotype seems to be associated with an increased activation of the NLPR3 inflammasome in macrophages infiltrating visceral adipose tissue, and a less favorable inflammatory profile compared with the MHO phenotype. Identification of the triggers that determine differential activation of the inflammasome between obesity phenotypes would likely help to better understand the pathophysiology of obesity-related metabolic disorders. Targeting inflammation, especially NLRP3 inflammasome, may offer potential novel therapeutic perspectives in the prevention and treatment of type 2 diabetes. [less ▲]

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See detailLung function and airway inflammation monitoring after hematopoietic stem
MOERMANS, Catherine ULiege

Doctoral thesis (2014)

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See detailTraitement des infections à entérobactéries productrices de béta-lactamase à spectre élargi: quelles alternatives aux carbapénèmes?
DESCY, Julie ULiege

Master of advanced studies dissertation (2014)

Introduction : Les entérobactéries productrices de β-lactamases à spectre élargi (BLSE) sont responsables d’un nombre important d’infections liées aux soins, mais aussi communautaires. Des alternatives ... [more ▼]

Introduction : Les entérobactéries productrices de β-lactamases à spectre élargi (BLSE) sont responsables d’un nombre important d’infections liées aux soins, mais aussi communautaires. Des alternatives thérapeutiques aux carbapénèmes devraient être utilisées, notamment à cause de l’émergence des bactéries productrices de carbapénèmase. Méthodes : Une étude prospective a été menée au CHU de Liège afin de déterminer le profil, clinique et microbiologique, de 30 patients infectés par une bactérie productrice de BLSE. Ces patients ont été divisés en 2 groupes (ceux traités par méropénème versus alternatives thérapeutiques) et différentes variables ont été analysées dont une évaluation de leur évolution clinique 14 et 28 jours après la date du prélèvement index de leur inclusion dans l’étude. Résultats : Sur les 30 patients inclus, 10 patients ont été traités empiriquement par méropénème : sur les 8 patients qui auraient pu bénéficier d’une antibiothérapie alternative, 4 traitements ont été changés une fois l’antibiogramme disponible. L’évolution clinique des 10 patients ayant bénéficié d’un traitement définitif par méropénème n’était pas statistiquement différente des 20 patients ayant reçu une antibiothérapie alternative. Lorsque les traitements empiriques par méropénème et pipéracilline-tazobactam sont pris en compte, l’intervention d’un infectiologue est associée à un taux plus élevé de réduction du spectre de l’antibiothérapie : 50% de réduction chez les patients ayant bénéficié de l’avis d’un infectiologue contre 29% chez les patients n’en ayant pas bénéficié. Conclusion : Une collaboration entre les microbiologistes, les infectiologues et les cliniciens permet aux patients, infectés par une entérobactérie productrice de BLSE, de bénéficier dans de nombreux cas d’une alternative thérapeutique aux carbapénèmes. [less ▲]

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See detailEpidémiologie de la lithiase urinaire en Province de Liège de 2011 à 2013
Castiglione, Vincent ULiege

Master's dissertation (2014)

Les calculs urinaires ont des compositions et des étiologies variées, qui sont réparties différemment dans les populations. Aucune donnée épidémiologique n’était disponible en Belgique, c’est pourquoi ... [more ▼]

Les calculs urinaires ont des compositions et des étiologies variées, qui sont réparties différemment dans les populations. Aucune donnée épidémiologique n’était disponible en Belgique, c’est pourquoi nous avons réalisé une étude rétrospective dans la Province de Liège, afin de déterminer la prévalence des nombreux constituants des lithiases. Nous avons également voulu analyser les paramètres qui lient les calculs uriques au syndrome métabolique. Plus de 1800 calculs ont été analysés entre 2011 et 2013 au CHU de Liège, le ratio hommes/femmes étant de 2,2. La globalité des résultats est similaire aux données épidémiologiques d’autres pays industrialisés, comme la France ou les USA. Une différence majeure est la prévalence élevée de calculs de weddellite chez les femmes âgées de 20 à 30 ans. La distribution des différents types de calculs est confirmée par l’analyse réalisée sur base de la classification morpho-constitutionnelle. De plus elle nous renseigne sur les associations prédominantes tels que les calculs mixtes II+IVa1, prévalant pour 11% de tous les types de calcul. Cette classification morphologique gagnerait donc à être davantage utilisée dans les études du monde entier. Concernant l’analyse sur les lithiases uriques, les résultats sont peu probants au vu du faible effectif de calculs réunis. [less ▲]

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See detailContribution à l’étude de la cryopréservation des cellules souches embryonnaires humaines à visée thérapeutique
Connan, Delphine ULiege

Doctoral thesis (2013)

Les cellules souches embryonnaires humaines (hES) sont caractérisées par une capacité d’autorenouvellement quasi-illimitée et une aptitude à se différencier en tous les types cellulaires caractéristiques ... [more ▼]

Les cellules souches embryonnaires humaines (hES) sont caractérisées par une capacité d’autorenouvellement quasi-illimitée et une aptitude à se différencier en tous les types cellulaires caractéristiques des trois feuillets embryonnaires primitifs. Elles sont considérées avec celles qui y sont étroitement apparentées, les cellules souches pluripotentes induites (iPS), comme une source virtuellement inépuisable de cellules pour la recherche biomédicale et les thérapies cellulaires. Cependant, leur utilisation clinique requiert efficacité optimale et sécurité biologique sans faille des procédés, matériels et réactifs utilisés. La cryopréservation est une étape clé indispensable pour le stockage et le transport de ces cellules, au cours de laquelle elles sont soumises à des conditions physiques et chimiques extrêmes, susceptibles d’altérer leur viabilité et leurs propriétés biologiques. Les méthodes efficaces de cryopréservation visent à garantir le maintien de ces propriétés tout en assurant le taux maximum de survie. De plus, un protocole optimal devrait permettre de préserver une grande quantité de cellules en une fois. Enfin, le respect des bonnes pratiques de fabrication (GMP) et la conformité aux directives européennes relatives à la manipulation et au stockage des cellules pour un usage thérapeutique requièrent la stérilité des échantillons, la reproductibilité, la traçabilité, la standardisation et l’automatisation du processus. Les cellules hES sont habituellement cryopréservées par congélation lente conventionnelle, dont les résultats peu satisfaisants en termes de survie cellulaire résultent essentiellement des dommages cellulaires liés à la cristallisation. Afin de réduire ces dommages, la vitrification a été développée comme méthode alternative pour la cryopréservation des embryons murins, bovins et, depuis peu, humains. Elle consiste en la transformation, sans cristallisation, d’un liquide en un solide amorphe par une augmentation brutale et infinie de sa viscosité. Pour que les liquides cellulaires atteignent cet état solide amorphe, la vitrification nécessite l’utilisation de concentrations élevées en cryoprotecteurs combinée à des vitesses de refroidissement et de réchauffement très élevées. Plusieurs groupes ont adapté les protocoles de vitrification aux cellules hES et ont montré que la vitrification est plus efficace que la congélation lente en termes de survie cellulaire et de maintien des cellules à l’état indifférencié. Cependant, la majorité des protocoles de congélation lente et de vitrification ne peuvent assurer la sécurité biologique de l’échantillon car les cellules sont stockées dans des conteneurs susceptibles de laisser pénétrer de l’azote liquide. De plus, à ce jour, aucun protocole de vitrification des cellules hES ne répond à l’ensemble des critères précédemment cités. La première étude présente notre nouvelle méthode de cryopréservation des cellules hES basée sur une vitrification aseptique dans des pailles scellées. En effet, le maintien de la stérilité et de l’absence de substances toxiques indésirables implique que tout contact direct des cellules avec l’azote liquide doit être évité. De plus, la méthode consiste en des additions successives de milieux avant refroidissement et après réchauffement, sans manipulation directe des cellules, ce qui la rend plus aisée à mettre en œuvre et compatible avec une automatisation. Les différents milieux utilisés sont chimiquement définis et biologiquement sûrs. Afin d’en estimer l’efficacité, nous l’avons comparée à la congélation lente conventionnelle. Nous avons montré que notre méthode de vitrification aseptique des cellules hES est aussi efficace que la congélation lente conventionnelle en termes de survie et est supérieure concernant le maintien de l’état indifférencié. Elle permet en outre de conserver leurs propriétés biologiques et cytogénétiques après réchauffement et expansion. La plupart des auteurs sont favorables à la vitrification pour la cryopréservation des embryons et cellules en termes de survie post-réchauffement. Cependant, les solutions auxquelles sont exposées les cellules au cours de la vitrification ont une concentration en cryoprotecteurs 3 à 4 fois supérieure à celles des solutions utilisées au cours de la congélation lente (4,8-6,4M versus 1,5M). Dans ce cadre, la seconde étude consiste à estimer la concentration intracellulaire en cryoprotecteurs (ICCP) lors de la vitrification et de la congélation lente. Pour ce faire, nous avons utilisé le zygote murin comme modèle cellulaire. Nous avons montré que l’ICCP lors de la vitrification est quasiment égale à 2,14M juste avant de plonger les cellules dans l’azote liquide, et équivaut donc au tiers de la concentration dans la solution vitrifiante (6,4M). De plus, nous avons montré que l’ICCP est plus basse après vitrification qu'après congélation lente. Nos résultats contribuent à expliquer pourquoi la vitrification est paradoxalement plus efficace que la congélation lente pour la cryopréservation des embryons et des cellules souches malgré l’utilisation de concentrations très élevées - potentiellement toxiques - en cryoprotecteurs dans les milieux. A notre connaissance, notre méthode de vitrification aseptique est la première méthode qui combine les diverses propriétés prédéfinies. Notre technique de cryopréservation est donc très prometteuse pour le stockage et le transport des cellules hES ou des cellules équivalentes, y compris dans le cadre d’applications cliniques qui exigent de hauts standards d’efficacité et de sécurité. [less ▲]

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See detailPathobiologie des anévrysmes de l'aorte abdominale: intérêts de la tomographie par émission de positons
Courtois, Audrey ULiege

Doctoral thesis (2013)

Les anévrysmes de l’aorte abdominale correspondent à une dilation de l’aorte infra-rénale de plus de 30 mm. Le risque de rupture d’un anévrysme a été longtemps considéré comme étant dépendant de son ... [more ▼]

Les anévrysmes de l’aorte abdominale correspondent à une dilation de l’aorte infra-rénale de plus de 30 mm. Le risque de rupture d’un anévrysme a été longtemps considéré comme étant dépendant de son diamètre, un paramètre qui constitue toujours le critère décisionnel le plus courant pour le traitement chirurgical des AAA. De nombreuses études ont cependant montré que la taille de l’anévrysme ne devait pas être le seul facteur à prendre en compte puisque certains anévrysmes de grande taille peuvent rester stables pendant des années sans signe de rupture tandis que d’autres rompent alors qu’ils n’avaient pas atteint une taille critique. Une accélération de la croissance ou l’apparition de douleurs doivent en revanche être considérés comme des signes alarmants. Il n’existe à l’heure actuelle aucun moyen ni marqueur fiable permettant de prédire l’évolution d’un anévrysme. La base de notre travail repose sur des études cliniques originales, réalisées dans le département de chirurgie cardiovasculaire en collaboration avec des services de médecine nucléaire, qui visaient à étudier la captation de 18F-Fluorodéoxyglucose ou FDG dans la paroi anévrysmale par tomographie à émission de positons couplé à un scanner ou PET/CT. D’abord limitée à quelques dizaines de patients, puis ensuite élargie plus récemment à quelques 400 cas, cette technique d’imagerie fonctionnelle a mis en évidence une captation de FDG reflétant une hyperactivité métabolique dans la paroi anévrysmale d’un nombre significatif de patients. Il a pu être établi que la captation de FDG au sein de l’anévrysme était associée à un taux de croissance accéléré et à la présence de symptômes, et qu’elle concordait parfois avec le site de rupture. Ces observations ont permis d’émettre l’hypothèse qu’une captation de FDG au sein de la paroi anévrysmale était synonyme de plus grande instabilité et d’un risque de rupture plus élevé. L’objectif majeur des travaux décrits dans ce mémoire était donc de comparer les altérations tissulaires, cellulaires et moléculaires présentes au sein de trois types d’échantillons anévrysmaux : les sites hypermétaboliques positifs au FDG, les zones quiescentes prélevées dans le même anévrysme à distance des sites de captation de FDG et des prélèvements réalisés sur des anévrysmes quiescents dans leur totalité. Cette approche devait nous permettre d’identifier des processus pathobiologiques locaux et globaux affectant la stabilité de la paroi aortique. Un premier volet de nos travaux a consisté à créer une banque d’échantillons biologiques (sang, pièces chirurgicales) provenant de patients suivis au moyen du PET/CT et atteints de différentes pathologies vasculaires. Dans la grande majorité des cas, ces échantillons ont été prélevés chez des patients souffrant d’un AAA soit quiescent (A0) ou présentant une zone hypermétabolique (A+). Dans ce dernier cas, les prélèvements de paroi anévrysmale ont été réalisés au site de fixation du FDG (A+pos) et dans une zone inactive située à distance de celui-ci (A+neg). Ces différents échantillons ont fait l’objet d’une étude histologique et biochimique des deux couches principales de la paroi : la media et l’adventice. Des altérations significatives susceptibles de représenter des processus avant-coureurs de la rupture ont été mises en évidence au sein du site de fixation du FDG, dont un infiltrat inflammatoire plus important, une perte des cellules contractiles de la media et un remodelage plus important de la matrice extracellulaire. De plus, des altérations de la paroi entière de l’anévrysme A+ sont également observées, suggérant ainsi des atteintes à la fois locales et systémiques. Afin d’élargir notre champ d’investigation, une analyse trancriptomique globale par micro-array a été réalisée sur ces différents échantillons. Nous avons ainsi pu déterminer de nouveaux facteurs surexprimés au niveau du site de captation de FDG et potentiellement impliqués dans l’instabilité de la paroi. Des facteurs modulés tant au site de captation de FDG qu’à distance de celui-ci au sein du même anévrysme pourraient constituer des biomarqueurs potentiels du développement et de la fragilisation de l’anévrysme dans son ensemble. [less ▲]

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See detailIntérêt de l'épidémiologie et des modèles animaux expérimentaux dans l'étude des valvulopathies en cardiologie humaine et équine
Leroux, Aurélia ULiege

Doctoral thesis (2013)

Valvular regurgitations are one of the most common causes of cardiac diseases in humans and in domestic animals. Clinical studies, epidemiological studies, and animal experimental models have been ... [more ▼]

Valvular regurgitations are one of the most common causes of cardiac diseases in humans and in domestic animals. Clinical studies, epidemiological studies, and animal experimental models have been developed to test new diagnostic and therapeutic techniques. Electrocardiography, Doppler echocardiography, angiography, magnetic resonance imaging (MRI) and computed tomography are currently used in clinical practice for diagnosis and prognosis. Medical management and, in humans, surgical treatments can increase life expectancy and improve quality of life of cardiac patients. In horses, cardiac clinical abnormalities including murmurs and arrhythmias are relatively common while the prevalence of clinically significant cardiac diseases is low. However, investigation of these with ECG and Doppler echocardiography is recommended as even mild cardiac abnormalities may lead to significant cardiac disease and cause poor performance in sport horses. To our knowledge, risk factors for several cardiac diseases have been suspected in equids. Few have been statistically demonstrated in a large equine population, since most studies about cardiac murmurs or arrhythmias concerned only racehorses. The first aim of this research work was to perform an epidemiological study in a large equine population to describe risk factors for various cardiac diseases. The prevalence of main cardiac diseases in the studied population was in accordance with previously described prevalence as mitral regurgitation (MR), atrial fibrillation (AF), aortic regurgitation (AR) and tricuspid regurgitation (TR) were the most frequently observed cardiac diseases. Various risk factors of these cardiac diseases were statistically demonstrated: Ageing and male gender appear to predispose to AR, TR appears to affect middle-aged patients, and AF was significantly more common in larger and heavier horses. Moreover MR was an important cardiac disease since it led to congestive heart failure (CHF) whereas AR was not a direct risk factor for CHF. Functional ischemic MR is one of the main human valvular diseases and is caused by ischemic cardiomyopathy with one or more prior myocardial infarctions involving most commonly the basal posterolateral myocardium of the left ventricle (LV). The therapeutic approach to functional MR is difficult and still controversy as regards the timing and the nature of the treatment. To our knowledge, no percutaneous large animal model of functional MR has been conceptualized. This model would be the first one to allow studying the dynamic component of functional MR. Therefore the second aim of this work was the development of an experimental animal model of functional ischemic MR. Goats appeared as good candidates for the model as they fulfill all requested conditions. They have a body and heart size comparable to that of humans and can be handled easily even during exercise tests. As few publications are available in this species, three first studies were designed to test the repeatability and to establish the reference values of measurements obtained using Two-Dimensional (2D), M-Mode, Pulsed-wave (PW) Doppler and 2D speckle tracking (2DST) echocardiography in unsedated standing adult goats. Standardized echocardiographic protocols were performed three times by the same observer at one day interval on 10 to 12 goats and the intra-observer inter-day repeatability and variability was calculated. 2D and M-Mode echocardiography showed a good inter-day repeatability and a low variability of the cardiac measurements, whereas PW Doppler measurements had a poor inter-day repeatability and a moderate variability. Caprine 2DST parameters demonstrated a poor but acceptable repeatability and a high variability and allowed determination of significant physiologic differences between measurements at rest and after exercise. Then the experimental model of functional ischemic mitral regurgitation induced by a percutaneous approach in goats was developed. This experimental study was conducted in two steps: first, the study of the goat coronary arteries anatomy to determine the best myocardial infarction location to induce ischemic MR in adult Saanen goats and, secondly, the development and the imaging characterization of the goat model of functional ischemic MR. The anatomic pattern of the coronary artery system of the goat was determined using casts made of auto polymerizing resin. Two coronary arteries branches were highlighted from the results of this anatomical study: the left marginal branch (LMB) and the posterior descending branch (PDB) of the left circumflex artery, which could supply the posterolateral wall of the LV. Then myocardial infarction was induced by microcoil embolization of LMB, PDB, or both, under fluoroscopic guidance. The results confirmed that LMB and PDB occlusion produced a large myocardial infarction and an immediate severe functional MR (n=3) unlike only LMB (n=2) or only PDB occlusion (n=2). Mortality rate of this model was high (56%), particularly when LMB and PDB were simultaneously occluded (87,5%). After the myocardial infarction, a complete follow-up was performed in each surviving goat using echocardiographic techniques previously described and MRI. 2DST techniques allowed quantifying LV dysfunction during acute ischemic MR. Quantification of functional MR was performed by Doppler techniques including measurements of the vena contracta width, the effective regurgitant orifice area and the regurgitant volume using the proximal isovelocity surface area method (PISA), and by 2D-echocardiographic technique analyzing the geometrical distortion of the mitral apparatus in mid-systole (tenting area and coaptation distance). Finally, MRI confirmed the location of myocardial ischemia and the presence of functional MR. These findings make this model an interesting alternative to study the pathophysiology of the functional ischemic MR, especially for its dynamic component yielding useful prognostic information. In conclusion, the two major aims of this research were met: the prevalence of various cardiac diseases and their risk factors in a large population of equids were described and an experimental model of functional ischemic mitral regurgitation induced by a percutaneous approach in goats was developed. This model of experimental ischemic MR could be useful to further study the pathophysiology of the functional ischemic MR, especially for its dynamic component and to maximize further treatment in problem patients. Our epidemiologic study confirmed that horses with cardiac murmurs or arrhythmias and presenting demonstrated risk factors, should routinely undergo ECG and Doppler echocardiography to diagnose and to evaluate the severity of any pathological cardiac abnormalities and to identify potential signs of evolution into CHF, including the presence of multiple cardiac diseases and enlargement of the cardiac chambers. [less ▲]

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See detailProgramme de revalidation multidisciplinaire post-cancer du sein : Analyse des bénéfices éventuels sur la fonction physique et la qualité de vie
Leclerc, Anne-France ULiege

Master's dissertation (2013)

Objectif : Le cancer du sein ainsi que ses traitements sont à l’origine de nombreux effets secondaires indésirables. Le but de l’étude est de déterminer les bénéfices éventuels, tant sur le plan physique ... [more ▼]

Objectif : Le cancer du sein ainsi que ses traitements sont à l’origine de nombreux effets secondaires indésirables. Le but de l’étude est de déterminer les bénéfices éventuels, tant sur le plan physique que psychologique, d’un programme de revalidation multidisciplinaire chez des femmes ayant été traitées pour un cancer du sein. Matériel et méthodes : L’étude constitue un essai clinique contrôlé non-randomisé comprenant deux périodes d’évaluations séparées par un intervalle de trois mois. Trente patientes ont été recrutées sur base d’une participation volontaire, seize faisant partie du groupe contrôle et quatorze du groupe traité. Celui-ci a bénéficié d’une prise en charge multidisciplinaire de trois mois comprenant des séances d’entraînement supervisé à raison de trois fois par semaine et des sessions psycho-éducatives une fois par semaine. Les évaluations ont inclus des mesures anthropométriques et de composition corporelle, un contrôle médico-sportif, une évaluation des capacités fonctionnelles et divers questionnaires relatifs aux fonctions physiques et psychologiques. Résultats : Au terme des trois mois de prise en charge, l’analyse statistique démontre une amélioration significative des paramètres tant psychologiques que physiques au sein du groupe traité. En effet, cette observation s’applique à l’état de santé (qualité de vie globale), à l’état émotionnel, aux fonctions physiques, cognitives et sociales, aux difficultés financières ainsi qu’aux symptômes d’insomnie et d’anxiété évalués par l’intermédiaire de questionnaires. Elle s’applique également à la souplesse, à la puissance maximale aérobie, à la puissance maximale aérobie / poids du corps, au temps jusqu’à l’épuisement lors du test d’effort sur bicyclette ergométrique et à la distance de marche en six minutes. Au sein du groupe contrôle, ces améliorations n’apparaissent pas. Conclusion : Cette étude préliminaire montre dès lors la faisabilité et les effets bénéfiques d’une prise en charge multidisciplinaire chez des femmes au terme de leurs traitements pour le cancer du sein. [less ▲]

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See detailLa charge vocale : De sa quantification à l’étude de son impact sur la fonction phonatoire et sur la qualité vocale
Remacle, Angélique ULiege

Doctoral thesis (2013)

Ce travail étudie la charge vocale principalement chez les enseignants. La prévalence élevée des troubles de la voix chez ces professionnels serait en partie liée aux trois facteurs principaux de charge ... [more ▼]

Ce travail étudie la charge vocale principalement chez les enseignants. La prévalence élevée des troubles de la voix chez ces professionnels serait en partie liée aux trois facteurs principaux de charge vocale que sont la durée de phonation, l’intensité et la fréquence vocale. Ces facteurs sont associés à des contraintes mécaniques appliquées aux plis vocaux lors de la vibration, potentiellement responsables de microtraumatismes du tissu, et participant au développement de pathologies vocales. Notre contribution intervient à deux niveaux d’étude de la charge vocale. Dans un premier temps, nous l’avons quantifiée en situation écologique dans une population d’enseignantes, en comparant deux niveaux de l’enseignement ordinaire belge : le maternel et le primaire. A cette fin, le comportement vocal de 12 enseignantes du maternel et de 20 enseignantes du primaire a été enregistré durant une semaine de travail, à l’aide d’un système de dosimétrie. Les objectifs étaient, d’une part, de déterminer les différences d’utilisation vocale selon le niveau d’enseignement, et d’autre part, de comparer l’utilisation vocale professionnelle et extra-professionnelle des enseignantes. Globalement, nos résultats montrent une charge vocale plus élevée en situation professionnelle qu’en situation extra-professionnelle. Par ailleurs, les enseignantes du maternel présentent une charge vocale plus élevée que celles du primaire, en termes de nombre de cycles vibratoires et de distance parcourue par les plis vocaux. Ces résultats suggèrent un risque accru de développer des pathologies liées à la charge vocale chez les institutrices du maternel. Dans un deuxième temps, nous avons étudié l’impact de la charge vocale sur la fonction phonatoire et sur la qualité vocale en condition de laboratoire. Une première condition expérimentale avait pour but d’améliorer la compréhension des facteurs de durée et d’intensité de la charge vocale, en soumettant 50 femmes normophoniques à 2 heures de charge, réalisées à deux reprises en variant le niveau d’intensité. Une seconde condition expérimentale avait pour but de comparer les effets de 2 heures de charge chez 16 enseignantes normophoniques et 16 enseignantes dysphoniques. Les effets de la charge vocale ont été évalués à l’aide de mesures objectives et subjectives. Les principaux résultats de la première condition expérimentale montrent plus d’impact de la durée que de l’intensité de la charge sur les paramètres observés. Dans la seconde condition expérimentale, peu de différences sont observées entre les deux groupes d’enseignantes au cours de la tâche de charge, suggérant que les enseignantes dysphoniques testées présentent une bonne résistance à la charge vocale. [less ▲]

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See detailMécanismes de l'anosognosie: une étude sémiologique et par imagerie fonctionnelle.
Jedidi, Haroun ULiege

Doctoral thesis (2013)

La maladie d’Alzheimer constitue une affection fréquente et très invalidante tant sur le plan individuel que social ou affectif. Elle s’inscrit comme un objectif majeur de recherche dans la mesure où elle ... [more ▼]

La maladie d’Alzheimer constitue une affection fréquente et très invalidante tant sur le plan individuel que social ou affectif. Elle s’inscrit comme un objectif majeur de recherche dans la mesure où elle constitue de par sa fréquence, les complications qu'elle entraîne et les soins multidisciplinaires lourds et coûteux qu'elle nécessite, un enjeu majeur pour l'économie de la santé des pays industrialisés. L’anosognosie qui complique souvent le décours de la maladie est un symptôme complexe, variable dans sa présentation tant au fil de l’évolution de la maladie que d’un patient à l’autre. La présence de l’anosognosie peut notamment compliquer le diagnostic ou la prise en charge voire mettre en jeu la sécurité du patient ou de ses proches. Elle peut, virtuellement, intéresser tous les domaines de la cognition. Tant sa prévalence que les mécanismes qui la sous-tendent au niveau anatomique ou fonctionnel demeurent méconnus et largement débattus dans la littérature. Dans cette optique, les corrélats neuraux de l’anosognosie doivent être mieux précisés et intégrés dans un modèle de fonctionnement global de la conscience de soi. Le domaine de l’anosognosie et en particulier celui de l’anosognosie portant sur les traits de la personnalité demeure donc un champ de recherche ouvert ou de nombreux travaux doivent encore être réalisés. C’est dans cette optique que nous avons choisi de mener notre étude. Le propos de notre ouvrage est donc l’étude des mécanismes de l’anosognosie par une approche tant comportementale que par le biais de la neuroimagerie fonctionnelle (IRMf et TEP). Au vu de l’étendue et de la complexité du sujet abordé, nous avons centré notre travail sur l’anosognosie portant sur les traits de personnalité. Au niveau cérébral, nous avons tout particulièrement étudié l’implication des régions préfrontales médiales dans ces processus de représentation de soi et dans la genèse de l’anosognosie portant sur les traits de personnalité. Notre première étude avait pour objectif d’étudier l’activité et la spécialisation fonctionnelle des régions préfrontales médiales au cours de la réflexion sur soi. Pour ce faire nous avons présenté à des volontaires jeunes une série d’adjectifs descriptifs. Durant l’acquisition en IRMf les sujets devaient juger à quel point ces adjectifs les décrivaient ou non. Juste après l’acquisition fonctionnelle, les sujets devaient à nouveau juger à quel point les mêmes adjectifs les décrivaient et de surcroît, ils devaient préciser à quel point ils avaient la certitude de posséder ou non ce trait de caractère et à quel point il était important pour eux de le posséder ou non. Les analyses de régression réalisées à partir de ces données ont démontré que l’activité au sein du cortex préfrontal dorsomédial étant corrélée à une évaluation de nature cognitive (certitude de posséder un trait de personnalité) et l’activité du cortex préfrontal ventromédial paraissant associée à des processus de nature émotionnelle (importance de posséder un trait de personnalité). Notre seconde étude avait comme objectif d’explorer les corrélats neuraux de l’anosognosie portant sur les traits de personnalité dans la maladie d’Alzheimer. Nous avons donc étudié une population de sujets présentant une maladie d’Alzheimer débutante et une population de sujets âgés sains auxquelles nous avons présenté divers questionnaires de jugement de personnalité. Nous avons également acquis une image du métabolisme cérébral de repos à l’aide de la TEP au 18 FDG chez ces patients et ces contrôles. Les résultats de cette étude suggèrent que l’anosognosie portant sur les traits de personnalité ne repose probablement pas entièrement sur un déficit de réactualisation des informations autobiographiques et du Self mais peut également être le fruit d’un déficit au niveau des capacités de prise de perspective à la troisième personne. Cette étude suggère également que le cortex préfrontal dorsomédial joue probablement un rôle dans ces mécanismes de prise de perspective. Notre troisième étude avait pour but d’évaluer le modèle dit « à deux voies » du syndrome de Capgras (Ellis et Young, 1997) qui constitue le modèle dominant de ce trouble dans la littérature et d’étudier l’implication des régions préfrontales médiales dans les processus de récupération des informations liées à un visage, de prise de perspective et de référence à autrui ou à soi-même. Pour ce faire nous avons acquis une image structurelle (en IRM) et une image fonctionnelle au repos (à l’aide de la TEP) du cerveau de notre patiente et nous avons comparé ces images à celles d’un groupe de sujets sains et de sujets présentant une maladie d’Alzheimer débutante. Les résultats de cette étude remettent quelque peu en question les corrélats anatomiques du modèle à deux voies du syndrome de Capgras et compte tenu des mécanismes actuellement connus de la reconnaissance des visages, semblent apporter de nouveaux arguments à l’hypothèse d’un rôle de centre d’intégration des informations liées à un visage et de la représentation d’autrui pour le cortex dorsomédial préfrontal. L’ensemble des résultats de ce travail démontre encore une fois combien les mécanismes de l’anosognosie et ceux de la conscience de soi sont complexes, intriqués et encore largement méconnus. Nous avons pu souligner l’importance du cortex préfrontal médial dans les processus de réflexion sur soi et d’évaluation du Self et en préciser la sous spécialisation fonctionnelle, l’activité au sein du cortex préfrontal dorsomédial étant corrélée à une évaluation de nature cognitive et l’activité du cortex préfrontal ventromédial paraissant associée à des processus de nature émotionnelle. Nous avons également pu démontrer que l’anosognosie portant sur les traits de personnalité actuelle semble davantage liée à une altération des capacités de prise de perspective tierce qu’à un déficit de réactualisation des informations autobiographiques (petrified Self). Ce dysfonctionnement des capacités de prise de perspective a également pu être corrélé à un dysfonctionnement (hypométabolisme) des régions préfrontales dorsomédiales. La dernière partie de notre travail nous permet en outre d’envisager et de mieux comprendre la complexité du rôle de ces structures préfrontales médiales et en particulier du cortex préfrontal dorsomédial, qui semble constituer, comme l’ont déjà suggéré plusieurs auteurs, un carrefour d’intégration important pour un ensemble complexe de processus cognitifs impliqués dans la représentation d’autrui, des ses intentions et de ses états mentaux, constituant ainsi une partie prenante du réseau cérébral ayant souvent été désigné par le terme de cerveau social (social brain). [less ▲]

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See detailLa neuroinvasion dans les maladies à prions: étude de l'interface neuroimmune FDC - système nerveux sympathique
Demonceau, Caroline ULiege

Doctoral thesis (2013)

Prion diseases are neurodegenerative diseases affecting the central nervous system (CNS) wherein the PrPd disease-associated prion infectious agent is an abnormal isoform of PrPc host-encoded cellular ... [more ▼]

Prion diseases are neurodegenerative diseases affecting the central nervous system (CNS) wherein the PrPd disease-associated prion infectious agent is an abnormal isoform of PrPc host-encoded cellular prion protein. The process through which the prion infectious agent is transferred to the CNS, the neuroinvasion, is still unknown, but secondary lymphoid organs seem to play an important role in prion amplification prior the invasion of the associated peripheral nervous system (PNS). In particular, modifications of follicular dendritic cells (FDC) and sympathetic nervous system (SNS) of lymphoid organs could influence the speed of neuroinvasion, and thus the length of the disease incubation period. It was shown that the lack of mature FDC prevents the replication of the infectious agent in secondary lymphoid organs. Likewise, sympathectomy delays the onset of the disease, and enhances sympathetic innervation reduces the incubation period. In mice, the relative positioning of FDC and sympathetic neural fibres plays a role in the incubation period following scrapie inoculation. This study thus focuses on the neuroimmune interface between FDC and sympathetic neural fibres. First, the number of close interactions between FDC and sympathetic neural fibres of five mouse strains with the same Prnpa genotype was estimated to check if it could explain the different incubation period observed after inoculation of primary bovine spongiform encephalopathy (BSE) infected-brain. Then we checked if scrapie infection, by oral or intraperitoneal route, could influence this neuroimmune interface between FDC and sympathetic neural fibres within Peyer’s patches (PP) and spleen of the C57BL/6 mouse strain. In the first part of this work, co-localizations between FDC and sympathetic neural fibres were observed in vivo within germinal centers (GC) of mouse spleen. Among the five mouse strains exhibiting the same Prnpa genotype, three strains (RIII-1, RIII-2 and 129/Ola) showed an incubation period about 100 days shorter than those of C57BL and C57BL/6 mouse strains when inoculated with primary BSE. Moreover, amplification by FDC seems an obligatory process before subsequent neuroinvasion as an intracerebral inoculation doesn’t reduce the incubation period observed with an intraperitoneal inoculation. A meticulous analysis revealed that the density of close interactions between FDC and sympathetic neural fibres is not higher for the three mouse strains with a shorter incubation period. However, these three mouse strains with a shorter incubation period after primary BSE inoculation have a higher proportion of FDC networks with close interactions than the mouse strains with a longer incubation period. These results suggest that it is not the quantity of sympathetic neural fibres close to FDC, but rather the percentage of FDC with close sympathetic neural endings that could influence the incubation period of prions diseases. In the second part of this work, it came out that prion infection did not result in neuronal loss within the PNS like observed in the CNS, and also did not modify the FDC-SNS neuroimmune interface of secondary lymphoid organs where PrPd deposits are observed within germinal centers. For a single mouse strain orally infected with scrapie, neither FDC networks hypertrophy nor sympathetic neural fibres closer than 10 μm from a FDC network were observed within GC of PP. Moreover, in our conditions, the prion strain did not seem to alter the neuroimmune interface between FDC and SNS in PP that could explain the different incubation periods observed with the 139A and ME7 scrapie strains. To check if prion infection does not modify the FDC-SNS neuroimmune interface, close interactions between FDC and sympathetic neural fibres already shown in the spleen were analyzed in the same mouse strain intraperitoneally infected with the 139A scrapie strain. In that case as well, no differences were observed in FDC network hypertrophy, in the in vivo density of sympathetic neural fibres closer than 10 μm from a FDC network, or in the proportion of well innervated FDC networks, compared to control mice. An in vitro model of coculture of splenic FDC from the same C57BL/6 mouse strain with nerve cells from dorsal root ganglia (DRG) also yielded similar results. FDC isolated from scrapie 139A infected mice exhibited the same neuritogenic or neurotrophic effects than FDC isolated from control mice. During these experiments, it was also noted that young-adult or middle-age mice showed both the same mean density of close interactions between FDC and SNS. However, with age, even if the splenic volume occupied by FDC networks halved, the proportion of FDC networks with close interactions almost doubled. It would be very interesting to check this last parameter in old mice that show some delay in neuroinvasion of prion disease but also to evaluate if this percentage of well innervated FDC network contributes to the prion pathogenesis within the spleen. In conclusion, scrapie 139A and ME7 strains don’t modify FDC-SNS neuroimmune interface of secondary lymphoid organs, not allowing explaining the different incubation period observed with equivalent infectious doses. Moreover, following an oral inoculation of prion, neuroinvasion within PP would not involve direct contact between FDC and sympathetic nerves, but rather another process still to be determined or implying other nerve fibres and/or mobile cells such as macrophages or dendritic cells. However, in the spleen, the percentage of FDC networks with close sympathetic neural fibres – rather than the number of sympathetic neural fibres close to the FDC network – observed for a given age, species and Prnp genotype at the time of inoculation could play a role in the different incubation periods observed for the same prion strain. The cellular compounds involved in the specific FDC microenvironment still have to be determined for each cell implied in the neuroinvasion process. [less ▲]

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See detailPattern Recognition in NeuroImaging: What can machine learning classifiers bring to the analysis of functional brain imaging?
Schrouff, Jessica ULiege

Doctoral thesis (2013)

The study of the brain development and functioning raises many question that are tracked using neuroimaging techniques such as positron emission tomography or (functional) magnetic resonance imaging ... [more ▼]

The study of the brain development and functioning raises many question that are tracked using neuroimaging techniques such as positron emission tomography or (functional) magnetic resonance imaging. During the last decades, various techniques have been developed to analyse neuroimaging data. These techniques brought valuable insight on neuroscientific questions, but encounter limitations which make them unsuitable to tackle more complex problems. More recently, machine learning based models, coming from the field of pattern recognition, have been promisingly applied to neuroimaging data. In this work, the assets and limitations of machine learning based models were investigated and compared to previously developed techniques. To this end, two applications involving challenging datasets were defined and the results from widespread methods were compared to the results obtained using machine learning based modelling. More specifically, the first application addressed a research question: Is it possible to detect and characterize mnemonic traces? The fMRI experiment comprised a learning and a control tasks, both flanked by rest sessions. From previous studies, patterns of brain activity generated during the learning task should be spontaneously repeated during the following rest session, while no difference should be observed between the pre- and post-task rest session in the control condition. Using univariate and multivariate feature selection steps before a Gaussian Processes classification, mnemonic traces could be detected and their spatio-temporal evolution characterized. On the contrary, an analysis of the rest sessions based on the detection of independent networks did not provide any results supporting the theory of memory consolidation. The second application tackled a clinical issue: Can a pattern of brain activation characteristic to idiopathic Parkinson’s disease be detected and localized? The dataset considered to address this question comprised the fMRI images of aged healthy subjects and Parkinsonian patients while they were performing a task of mental imagery of gait at three different paces. The signal comprised in a priori selected regions of interest allowed for the support vector machines classification of healthy and diseased volunteers with an accuracy of 86%. To localize the discriminating pattern, a methodology based on the weight in labelled regions (e.g. from the anatomical automatic labelling or Brodmann atlases) was developed, which enabled the comparison between univariate and multivariate results and showed a nice overlap between them. Furthermore, models could then be compared quantitatively in terms of pattern localization, using a specifically defined measure of distance. This measure could then be used to compare the patterns generated from different folds of a same model, from different feature sets, or from different modelling techniques. The present study concluded that machine learning models can clearly and fruitfully complement other analysis techniques to tackle challenging questions in neuroscience. On the other hand, more work is needed in order to render the methodology fully accessible to the neuroscientific community. [less ▲]

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See detailThe functional neuroanatomy of tinnitus: insights from resting-state fMRI
Maudoux, Audrey ULiege

Doctoral thesis (2012)

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See detailExtending Donor Pool with Donation after Cardiac Death in Kidney and Liver Transplantation:What is the Price to Pay?
Le Dinh, Hieu ULiege

Doctoral thesis (2012)

Through a series of clinical studies, this thesis aims to clarify the contribution of donation after cardiac death (DCD) to the deceased donor (DD) pool and results of kidney and liver transplantation ... [more ▼]

Through a series of clinical studies, this thesis aims to clarify the contribution of donation after cardiac death (DCD) to the deceased donor (DD) pool and results of kidney and liver transplantation coming from this donor source in Liège and Belgium. Additionally, an adapted DCD Maastricht classification is also discussed. Chapters 2.1 and 2.2 summarize the DCD procurement and transplant activity in Liège and Belgium from 2000 to 2009 with an update on data up to 2011. In Liège, DCD really contributes to the DD pool and boosts the transplant activity of the center in both kidneys and livers by on average 30%. By contrast, the steady rise in DCD activity in Belgium does not lead to major increase in the DD donation and transplantation. In other words, some kind of donor-type redistribution within the DD pool might occur. Chapters 2.2, 3.1, and 3.2 discuss the results of kidney transplantation (KT) from DCD. We demonstrate that Liège‟s experience is comparable to the national level in Belgium and does not differ from the general results in the world with regard to early graft dysfunction, medium-term graft function, graft and patient survival. The excellent results of DCD-KT are attributed to the relatively short warm and cold ischemia, favorable donor factors, and the role of hypothermic machine perfusion (in Belgian series). Chapters 4.1, and 4.2 discuss the results of liver transplantation (LT) from DCD. Liège‟s results are encouraging and apparently as good as those from donation-after-brain-death LT because of short warm and cold ischemia times. Belgian results show an increased incidence of primary non-function and ischemic cholangiopathy which is in agreement with previously published data. Chapter 5 proposes an adapted DCD Maastricht classification which maintains the original categories 1 to 4 that are now well-known and widely accepted, and adds a fifth category, so-called „DCD after euthanasia‟. Each category is divided into two or three sub-categories: sub-category A is linked to longer warm ischemia (and worse results) than sub-category B; and B versus C, respectively. In addition, sub-categories A (2A, 3A, 4A, and 5A) are mostly linked to DCD processes occurring in the ICU, which helps to understand and memorize this classification. By keeping the original skeleton of the 1995 Maastricht classification, room is left to add new sub-categories in the future, if deemed clinically relevant. [less ▲]

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See detailEtude du rôle de l’Hypoxia Inductible Facteur 1 dans les cellules myéloïdes lors d'allergie des voies respiratoires
Toussaint, Marie ULiege

Doctoral thesis (2012)

Adaptive Th2 immune responses play a major orchestrating role in the development of airway allergy in mammals. It is currently known that the induction of Th2 responses closely depends on the activation ... [more ▼]

Adaptive Th2 immune responses play a major orchestrating role in the development of airway allergy in mammals. It is currently known that the induction of Th2 responses closely depends on the activation of innate immunity. Through its action on innate immune cells, Hypoxia inducible factor 1 (Hif1) has been described as a major regulator of inflammatory responses. Airway allergy is a disease whose incidence is in constant increase in developed countries, and the potential implication of Hif1 in innate immune cells during the development of such disease remains currently unknown. Therefore, we were interested in the involvement of Hif1 within innate immune cells in two experimental models of allergic airway inflammation: allergic asthma and recurrent airway obstruction (RAO). Recurrent airway obstruction is one of the most frequent respiratory syndrome that veterinary equine practice has to deal with in our countries. In the case of RAO, the role of the innate immune system, representing the first line of host defense, has not been investigated so far. We have therefore looked at the potential implication of Hif1 in pulmonary innate immune cells during this disease. We have found that, upon allergenic challenge, Hif1 expression within pulmonary innate immune cells was significantly increased in RAO-affected horses in comparison to the control animals. In addition, Hif1 expression was positively correlated to the severity of clinical dysfunctions in RAO-affected horses. We have also shown that the presence of hay-derived LPS could specifically increase Hif1 expression in macrophages. As previously described in other models of inflammation, these results allowed us to show, in a model of RAO, that Hif1 plays a pro-inflammatory role in innate immune cells. Since 90% of innate immune cells of a healthy horse are macrophages, we decided to further investigate the implication of Hif1 in lung myeloid cells. In the second study, for technical reasons, we decided to focus on another model of airway allergy, namely allergic asthma. Although molecular and cellular mechanisms governing asthma development are well characterized, very few information is available regarding the mechanisms that can prevent the development of this disease in healthy subjects. The identification of such mechanisms could be key to understand the origin of development of that epidemic disease as well as to improve the strategies of prevention. We have found that mice that were specifically deficient in Hif1 within myeloid cells (Hif1αm-/-) developed significantly more allergic inflammation in comparison to control mice. We have further shown that these mice had a higher inclination to develop a Th2 response upon allergenic challenge. We then proved that the increase of antigen-specific Th2 responses in Hif1αm-/- mice was the result of increased lymph node dendritic cells migration and antigen presentation. These results suggested that a brake to DC activation by allergens was lost following deletion of myeloid Hif1. Finally, we have found that the specific deletion of Hif1 in interstitial macrophages was indeed responsible of the observed effects. Indeed, we have shown that the TLR-dependent activation of Myd88 in interstitial macrophages induced increased expression of Hif1, thereby increasing IL-10 production from interstitial macrophages. In addition, following HDM stimulation, we observed that Hif1αm-/- interstitial macrophages produced significantly less IL-10 than control interstitial macrophages. Since we have previously shown that interstitial macrophages were capable of blocking dendritic cell activation through the production of IL-10, we proposed that Hif1 was able to control the immunoregulatory functions of interstitial macrophages by regulating their IL-10 production. Our work revealed a crucial role for Hif1 in interstitial macrophages for maintaining the immune homeostasis in the lung. It also suggests for the first time that Hif1 within innate immune cells can display an anti-inflammatory role. As a conclusion, we have been able to assess the importance of Hif1 activation within innate immune cells in the regulation of airway allergy development. We have further proposed that a compartmentalization of pro- and anti-inflammatory functions of Hif1 exists in immune cells. In opposition to what we obtained in the first study and what is currently known in the literature; we have found an anti-inflammatory role for Hif1 in innate immune cells. Indeed, thanks to its role in interstitial macrophages, Hif1 can play a crucial role in the prevention of aberrant immune responses against harmless antigens by preventing allergic sensitization. Hif1 therefore plays a key role in maintaining lung mucosal immune homeostasis. [less ▲]

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See detailSubstrats cérébraux des processus moteurs automatiques et inconscients
D'Ostilio, Kevin ULiege

Doctoral thesis (2012)

Les mécanismes à la base des troubles du contrôle moteur sont encore peu compris. L'étude des patients akinétiques et hyperkinétiques soulignent l’importance physiopathologique du cortex (pré)moteur et ... [more ▼]

Les mécanismes à la base des troubles du contrôle moteur sont encore peu compris. L'étude des patients akinétiques et hyperkinétiques soulignent l’importance physiopathologique du cortex (pré)moteur et des noyaux gris centraux. Ces études ne nous permettent cependant pas de déterminer le rôle respectif de ces différentes régions. Les modèles actuels suggèrent que certains mouvements anormaux résultent d’une perturbation de l’équilibre entre les processus de facilitation et d’inhibition des programmes moteurs secondaire à une altération de l’intégration perceptuo-motrice. Dans le cadre de ce travail, nous avons utilisé une tâche d'amorçage subliminale afin d'examiner les corrélats cérébraux de ces processus chez des sujets jeunes ainsi que chez des patients atteints de la maladie de Parkinson. Nous avons montré que l'activation/facilitation et l'inhibition automatiques et inconscientes étaient sous-tendues par un réseau moteur cortico-sous-cortical. Ce résultat a été ensuite confirmé au moyen d'une approche lésionnelle par l'étude de patients parkinsoniens. Nous avons également mis en évidence une dépendance cingulo-préfrontale dans la détection /résolution de conflit inconscient. Ces résultats remettent en cause les théories traditionnelles considérant la conscience et le contrôle cognitif comme étant étroitement reliés et contribue à une meilleure compréhension de la physiopathologie des mouvements anormaux. [less ▲]

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See detailThe role of sleep in the consolidation of rewarded and relational memory
Gaggioni, Giulia ULiege

Master's dissertation (2012)

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See detailLe sommeil chez les patients en état de conscience altéré
Cologan, Victor ULiege

Doctoral thesis (2012)

Cet ouvrage décrit les études réalisées sur le sommeil des patients cérébro-lésés en état de conscience altérés et présente nos travaux effectués chez les patient en état végétatif et en état de ... [more ▼]

Cet ouvrage décrit les études réalisées sur le sommeil des patients cérébro-lésés en état de conscience altérés et présente nos travaux effectués chez les patient en état végétatif et en état de conscience minimale. Les conclusions supportent l'intérêt neurophysiologique mais aussi diagnostique et pronostique de l'examen du sommeil chez ces patients. [less ▲]

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See detailCancer du sein inflammatoire: aspects épidemiologique, anatomopathologique, moléculaire et viral à propos de 219 cas colligés à l'Institut National d'Oncologie (Rabat/Maroc)
Zoure, Abdou Azaque ULiege

Master's dissertation (2012)

Inflammatory breast cancer represents a special clinical entity characterized by its rarity, rapid evolutionary pace and poor prognosis. We conducted a retrospective study over 6 years (2005-2010) and we ... [more ▼]

Inflammatory breast cancer represents a special clinical entity characterized by its rarity, rapid evolutionary pace and poor prognosis. We conducted a retrospective study over 6 years (2005-2010) and we identified 219 cases of inflammatory breast cancer (IBC) diagnosed and treated at the National Institute of Oncology (INO) Hospital Sidi Mohamed Ben Abdellah, Rabat. The diagnosis was clinical as defined by AJCC (American Joint Cancer Committee). Thus, we found an incidence of 4.09% of IBC. All patients were female. The mean age was 47.31 years (26-75 years) and 60.72% of the patients were younger than 50 years. The rate of non-menopausal women is 51.14% and 69.58% were multiparous. Over 60% of patients were either obese (body mass index or BMI ≥ 30 kg/m2) or overweight (25 <BMI <30). On histology, invasive ductal carcinoma is predominant representing 93.23% of cases. SBR Grade I SBR (Scarff Bloom Richardson) was encountered in only 7, 11% of cases. Estrogen receptor (ER) and progesterone receptor (PR) were negative in respectively 44.78% and 30.50%, and HER2 was positive in 33.07%. Molecular classification showed 41.60% luminal A subtype, 19.46% grouped in the luminal B subtype, 17.70% HER2 + subtype and 21.24% Triple negative subtype. Lymph node infiltration was clinical in 60.85% and histological in 85.19% of the cases 28.77% were initially metastatic. Vascular emboli were found in 72.67% cases. The preliminary study of MMTV-like virus detection focused on 37 cases including 31 cases of IBC and 6 cases of non-inflammatory breast cancer (NIBC). One PCR was used for the detection of MMTV-like in paraffin embedded tissues. The results show the presence of DNA sequences of the Env region of MMTV-like virus in 64.51% of IBC cases and 50% of NIBC cases. [less ▲]

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See detailApplication d’un modèle d’analyse de l’interaction ventriculo-artérielle à la défaillance hémodynamique
MORIMONT, Philippe ULiege

Doctoral thesis (2012)

L’utilisation du modèle hémodynamique d’interaction ventriculo-artérielle au lit du malade, à la place des approches intuitives dépourvues de signification physiologique réelle, est un défi. La nécessité ... [more ▼]

L’utilisation du modèle hémodynamique d’interaction ventriculo-artérielle au lit du malade, à la place des approches intuitives dépourvues de signification physiologique réelle, est un défi. La nécessité de recourir à des mesures hautement invasives et à des variations de pré-charge reste une contrainte difficile chez des patients instables. Les recherches présentées dans cette thèse montrent que les indices nécessaires à l’application du modèle peuvent aussi être obtenus à partir de mesures ou de signaux utilisés usuellement en soins intensifs à condition de respecter des conditions précises. [less ▲]

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See detailContribution to the phytochemical study of indolomonoterpenic alkaloids isolated from Strychnos usambarensis and investigation of their activity on Plasmodium falciparum
Cao, Martine ULiege

Doctoral thesis (2012)

Our research focuses on the extended study of antimalarial and anticancer alkaloids isolated from Strychnos usambarensis (leaves and fruits), and is subdivided into two main axes: - The development of a ... [more ▼]

Our research focuses on the extended study of antimalarial and anticancer alkaloids isolated from Strychnos usambarensis (leaves and fruits), and is subdivided into two main axes: - The development of a purification method for natural compounds such as tertiary indolomonoterpenic alkaloids (in particular for isostrychnopentamine or ISP) to improve the isolation process and to get significant quantities of purified compounds. - The investigation of the pharmacological properties of ISP, especially on Plasmodium falciparum. The first part of the thesis is devoted to the phytochemical study of S. usambarensis leaves. It includes the development and the optimization of a simple and rapid HPLC method in order to perform a one-step-transposition in preparative scale (J Pharm Biomed Anal, 2011). In parallel to this work, a brand new alkaloid was isolated from the crude alkaloid extract of S. usambarensis leaves, 17-O-acetyl, 10-hydroxycorynantheol. The compound, assessed for its antiplasmodial activity on the 3D7 and W2 strains of P. falciparum, represents one of the most active monoindolic alkaloid known to date with a remarkable selectivity for the parasite (Planta Medica, 2011). Fruits were also investigated in order to identify the main components and maybe the presence of ISP. Two major alkaloids were characterized by analytical HPLC and were therefore studied in LC-NMR and mass spectrometry (MS) after solid phase extraction (SPE): palicoside and akagerine (Phytochem Letters, 2012). In addition, we also carried out hemisynthesis of isostrychnopentamine during the PhD mandate. The concept was to hemisynthetize ISP from 11-OH usambarine, a tertiary alkaloid more abundant in the leaves. Unfortunately, the first experiments were not as conclusive as expected. The second part of the thesis concerns the investigation of the mode of action of ISP on P. falciparum. A metabolomic approach displaying the metabolomic differences induced in the parasites was combined to a transcriptomic study evaluating genes expression via a microarray analysis, in order to better understand the biological processes involved in P. falciparum in response to ISP. For this purpose we performed a study in 1H NMR metabolomics on culture media of P. falciparum under ISP treatment. In addition, we investigated gene activation using microarrays and analyzed the alterations of the P. falciparum 3D7 transciptome in synchronous cultures after exposure to ISP. Differences in gene expression were highlighted: out of the 4700 genes analyzed, 84 were differentially expressed, 40 over-expressed and 44 under-expressed and some of them were related to specific metabolic pathways. [less ▲]

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See detailContribution à l'étude des effets précoces de perturbateurs endocriniens sur l'axe hypothalamo-hypophysaire et la maturation sexuelle de la rate : aspects mécanistiques in vivo et in vitro
Rasier, Grégory ULiege

Doctoral thesis (2012)

En résumé, nous avons mis en évidence un effet stimulant des isomères oestrogéniques du DDT sur la sécrétion pulsatilité de GnRH ainsi que sur la sécrétion de GnRH induite par le glutamate chez le rat ... [more ▼]

En résumé, nous avons mis en évidence un effet stimulant des isomères oestrogéniques du DDT sur la sécrétion pulsatilité de GnRH ainsi que sur la sécrétion de GnRH induite par le glutamate chez le rat femelle immature. Le DDT entraîne un effet stimulant similaire à celui de l’E2, mais à des concentrations 100 à 1000 fois plus élevées que le stéroïde. Cette différence de concentration est cohérente avec les observations faites dans d’autres modèles in vivo et in vitro. Par nos travaux, nous fournissons une preuve que le DDT peut influencer la maturation hypothalamo-hypophysaire femelle infantile via une accélération développementale précoce de la sécrétion de GnRH démontrée in vitro et une réduction précoce de la LH en réponse à la GnRH démontrée in vivo. Nous montrons aussi que cet insecticide cause une puberté précoce in vivo quand des individus immatures y sont exposés durant une période limitée. Les PEs, en particulier l’o,p’-DDT, peuvent moduler la sécrétion de GnRH in vitro dans l’hypothalamus femelle immature à travers à la fois des effets rapides et lents avec l’implication des ERs, du AhR et du sous-type AMPA des récepteurs au glutamate, ainsi que via les kinases intracellulaires A, C et MAPK. [less ▲]

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See detailModeling external and internal drug exposure: assessing their causal biomedical consequences
Comté, Laetitia ULiege

Doctoral thesis (2012)

C’est un fait notoire que beaucoup de patients ne suivent pas parfaitement le traitement prescrit par leur médecin mais se permettent bien des écarts. Cependant, à notre époque où les thérapies sont de ... [more ▼]

C’est un fait notoire que beaucoup de patients ne suivent pas parfaitement le traitement prescrit par leur médecin mais se permettent bien des écarts. Cependant, à notre époque où les thérapies sont de plus en plus pointues et où, pour certaines maladies, un suivi strict du régime thérapeutique est essentiel, toute variation par rapport à ce régime peut être dommageable à l’efficacité du traitement. Cette non-adhésion aux traitements prescrits à été scientifiquement étudiée dès la seconde moitié du vingtième siècle et plus particulièrement, ces trente dernières années. Il a été ainsi prouvé qu’elle est une des causes premières dans la diversité des réponses cliniques aux traitements. Comme l’a dit le médecin général des Etats-Unis, Everett Koop, “Les médicaments ne fonctionnent pas pour des patients qui ne les prennent pas” (i.e. “Drugs don’t work in patients who don’t take them”). L’avènement des piluliers électroniques a révolutionné la recherche sur l’adhésion des patients au régime thérapeutique prescrit. En effet, ces piluliers permettent aujourd’hui de mémoriser l’historique de la prise du médicament de chaque patient grâce à un circuit électronique dans leur couvercle qui enregistre la date et l’heure de chaque ouverture. De telles nouvelles données devaient être exploitées de manière optimale. Comment y parvenir? Afin de répondre à cette question, il est tout d’abord nécessaire de préciser exactement la signification de ce concept d’‘adhésion à un traitement’ (en anglais: ‘adherence’ ou encore en français ‘observance’). Cette adhésion d’un patient à un traitement a été définie comme une mesure globale de la conformité de l’historique de prises de ce patient avec celui qu’il aurait connu s’il avait suivi le régime thérapeutique prescrit (Sackett and Haynes 1976). Une mesure globale est le plus souvent insuffisante pour une étude appronfondie des cas de non-adhésion. Pour le prouver, considérons par exemple le cas d’un patient qui doit prendre un médicament 2 fois par jour pendant 4 mois. S’il ne prend que la dose du matin pendant 4 mois, son adhésion sera évaluée à 50%. Toutefois, s’il prend ses deux doses correctement mais seulement pendant 2 mois puis qu’il stoppe le traitement, son adhésion sera également évaluée à 50%. PPourtant ces 2 types de comportement risquent d’engendrer des conséquences pharmacologiques bien différentes. On sépara alors le concept d’adhésion en trois composantes : l’initiation, l’exécution du régime thérapeutique et la persistance au traitement. Ainsi, dans le premier exemple repris ci-dessus, l’exécution du régime est incorrecte mais la persistance est maximale (4 mois) tandis que dans le second, l’exécution du régime est correcte mais plus la persistance (2 mois). La persistance correspond à la durée totale depuis l’initiation, correspondant à la première prise, jusqu’à l’arrêt du traitement. L’exécution du régime thérapeutique est une notion plus délicate à caractériser car elle peut varier de différentes manières et tout au long du traitement; c’est donc une variable multidimensionnelle. Elle résulte de la comparaison entre l’historique de prises du patient, tant que celui-ci est engagé dans le traitement, avec l’historique de prises attendu par le régime thérapeutique prescrit. Malheureusement, la mesure de l’exécution du traitement est trop souvent ramenée à un simple pourcentage (par exemple, le pourcentage des doses prescrites effectivement prises sur un intervalle de temps déterminé ou encore le pourcentage de jours où le nombre de doses prescrites à été respecté, etc...) que certains chercheurs exploitent en fixant arbitrairement une valeur qui permet de répartir les patients en deux groupes: ‘bons’ ou ‘mauvais’ exécutants. Cette valeur arbitrairement choisie fait pourtant bien peu de cas de cette question essentielle et toujours présente: ‘Comment peut-on juger si l’adhésion est suffisante?’. Pour illustrer la faiblesse de cette façon de faire, citons Harrigan (2005) qui montra que, pour des patients séropositifs, une haute mais non parfaite exposition au médicament, exposition que l’on aurait tendance à juger suffisante, peut s’avérer plus dommageable en terme de résistance au traitement qu’une plus faible exposition. En effet, sur base des relevés d’ordonnances pharmaceutiques (‘prescription refill data’), il montra que c’est dans la tranche 80% à 90% de doses achetées par rapport aux doses prescrites qu’il y a le plus risque de développer une résistance au traitement. Voilà donc pourquoi, dans la première partie de cette thèse, notre but a été d’étudier toute une série de façons de mesurer l’exposition au traitement afin de déterminer celle(s) qui engloberai(en)t le plus de caractéristiques de l’historique des prises. Après avoir présenté le concept d’adhésion au premier chapitre, nous avons examiné au chapitre suivant non seulement les pourcentages classiques de doses prises, mais aussi la variabilité du moment de la prise du médicament en prenant soin de distinguer l’étude des prises du matin de l’étude de celles du soir, la distribution des intervalles de temps entre les doses successives, l’occurrence de doses manquantes consécutives, etc... Nous avons ainsi obtenu 26 variables résumant l’historique de doses prises. Nous avons cherché ensuite à identifier 3 groupes de patients via la méthode de classification de Hartigan (Hartigan K-Means Clustering method). Notre but étant de caractériser l’exécution du traitement pour les patients de chaque groupe par les variables les plus pertinentes parmi les 26 variables obtenues, nous avons proposé un algorithme basé sur la théorie du ‘multidimensional scaling’ qui nous permet de garder les principales caractéristiques des données de chaque groupe malgré la réduction de l’ensemble des variables. Cela nous a permis de mettre en évidence que les variables sources principales de discrimination en groupes de patients sont relatives à la quantité de doses prises. Il s’est avéré que ces mêmes variables expliquent également la non-persistance des patients, tout comme certaines variables relatives à la variabilité dans les moments de prise du médicament. Cela conforte l’idée qu’une mauvaise exposition pourrait entraîner l’arrêt du médicament (non-persistance). Ces efforts de classification n’ont cependant pas suffi à obtenir une caractérisation claire des groupes de patients. En effet, chaque patient peut dévier du traitement prescrit de multiples et diverses façons durant son traitement (par exemple, une fois en manquant la dose du soir, une autre fois celle du matin, ou encore celle du samedi ou celle du mercredi ou en montrant une grande variabilité dans ses prises sur une certaine période,...). Dans un second temps, cherchant toujours une mesure de l’exposition au traitement englobant le plus de caractéristiques de l’historique des prises, nous avons investigué une mesure de l’exposition au traitement via la concentration du médicament dans le sang. Il s’agit donc d’une mesure ‘interne’ de l’exposition au traitement du patient. Elle combine les acquis de la pharmacocinétique à l’historique des prises du patient (Vrijens et al 2005b). Puisque cette mesure interne requiert l’utilisation d’un modèle pharmacocinétique, ce type de modèle est présenté au Chapitre 3. Ensuite, au Chapitre 4, nous avons utilisé cette mesure interne de l’exposition pour comparer deux régimes de prises d’un médicament: une fois par jour (QD) et deux fois par jour (BID) pour des patients séropositifs. Nous avons ainsi pu montrer que le régime QD permet un moins grand nombre d’oublis du médicament que le régime BID par contre tout oubli affecte plus gravement la concentration du médicament dans le sang que le régime BID (L. Comté et al 2007). La deuxième partie de cette thèse a pour but d’intégrer les mesures d’exposition aux modèles statistiques permettant d’évaluer l’efficacité d’un traitement. Les méthodes statistiques classiques ne tiennent pas compte de la façon dont le traitement a été pris (exposition au traitement) et permettent donc seulement d’étudier l’effet moyen du traitement tel qu’il a été prescrit aux patients. Pourtant, dans certains cas, et surtout avec des traitements de longues durées (maladies chroniques : infection par VIH, diabète, etc), il devient intéressant, en vue de l’évaluation de l’effet d’un traitement, d’intégrer aux modèles la façon dont le patient a respecté le régime médicamenteux qui lui a été prescrit. Mais une difficulté apparaît puisque les modèles statistiques classiques de régression ne permettent pas l’interprétation causale directe de l’effet de la mesure de l’exposition sur la réponse clinique au traitement. En effet, l’exposition ne se mesurant qu’après l’échantillonnage, elle peut donc elle-même être influencée par la réponse clinique (Lee et al 1991; Goetghebeur and Pocock 1993). En présence de telles interactions possibles, des modèles spéciaux (‘causal models’) sont nécessaires pour une estimation non biaisée de l’effet de la dose prise. Jusqu’aujourd’hui, les méthodes basées sur les modèles structuraux moyens (structural mean models) développés par Robins (Robins 1994; Fisher-Lapp and Goetghebeur 1999) sont celles qui permettent le plus de flexibilité mais sont pourtant peu utilisées dans la pratique en raison de leur plus grande complexité par rapport aux modèles statistiques classiques. De ce fait, elles sont également moins souvent représentées dans les logiciels informatiques. Ainsi, au Chapitre 5, nous avons détaillé le modèle structural moyen log-linéaire ainsi qu’introduit un nouvel outil diagnostique pour les modèles structuraux moyens linéaires et log-linéaires. Nous avons ensuite appliqué ces modèles à un ensemble de données concernant des patients souffrant de problèmes gastriques, randomisés entre un traitement et un placebo tous deux prescrits ‘à la demande’. Ce régime, comme son nom l’indique, demande aux patients de prendre le médicament lorsque les symptômes apparaissent ce qui constitue un cas particulièrement représentatif de la nécessité d’utiliser un modèle spécial afin d’éviter un biais puisque l’exposition dépend de l’état clinique du patient (L. Comté et al 2009). Pour parachever cet ouvrage, nous avons combiné, au Chapitre 6, la mesure interne de l’exposition au traitement (via la pharmacocinétique) et les modèles structuraux, pour mesurer l’évolution de la charge virale en fonction de cette exposition interne pour des patients séropositifs n’ayant jamais reçu de traitement auparavant. Pour ce type de patients, la décroissance de la charge virale est en effet un bon indicateur du succès du traitement. Il devient dès lors intéressant de quantifier la relation causale entre l’exposition interne (mesure pharmacocinétique) et la décroissance de la charge virale. Comme on s’intéresse à l’évolution de cette charge virale au cours des visites, l’exposition interne sera mesurée entre chaque visite c’est-à-dire sur des intervalles de temps. Les modèles structuraux moyens emboîtés (Structural nested mean models) sont alors détaillés et ensuite utilisés afin d’estimer cette relation causale entre les différentes séquences d’expositions internes et l’évolution de la charge virale. Nous avons ainsi pu mettre en évidence une réduction substantielle et significative de la charge virale pouvant être attribuée à l’exposition interne au médicament d’un patient tant qu’il est en phase décroissante. Cette réduction sera d’autant plus importante que la charge virale était élevée à la visite précédente (L. Comté et al 2011). En résumé, nous pensons que notre travail permet de mieux cibler le challenge d’une modélisation adéquate de l’exposition au traitement et donc l’utilité d’une mesure interne au patient. De plus, il permet de mieux comprendre l’impact de l’exposition au traitement sur l’efficacité d’un traitement. [less ▲]

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See detailContribution to the statistical evaluation of data obtained in External Quality Assessment programmes
Coucke, Wim ULiege

Doctoral thesis (2012)

Laboratory medicine has undergone a spectacular evolution in the last decades and has become today of crucial importance for supporting diagnostic and therapeutic decisions. The increase of the volume of ... [more ▼]

Laboratory medicine has undergone a spectacular evolution in the last decades and has become today of crucial importance for supporting diagnostic and therapeutic decisions. The increase of the volume of laboratory analyses has not gone without an emerging risk of measurement errors that may have far-reaching consequences, even on the patient’s life. External Quality Assessment (EQA), already established since several decades in various countries and often running on an international level, aim at going further than the "internal quality control" procedures of every laboratory and at improving laboratory quality by inter-laboratory comparisons. An EQA round generally consists of sending aliquots of the same sample to various laboratories for assaying selected tests. After finishing the assays, results are reported back to the EQA organizer. Subsequently these results are subject to a statistical analysis, which is performed globally, for all the participants, or for each analytical technique separately. Finally, a report is sent to every participant that informs about the acceptability of the individual results, with respect to predefined limits, and with respect to the group of peers. This thesis, structured in five chapters, focuses on the External Quality Control of clinical laboratories by a critical analysis of existing methods and by creating new approaches that permit to improve the current procedures. The first chapter of this work emphasizes the evolution of the role of the clinical laboratory and EQA in the quality improvement. After the report ’To Err is Human: Building a Safer Health System’, numerous scientists became interested in investigating the frequency, source and impact of laboratory errors. The Total Testing Process (TTP) became recognized as the best framework to investigate laboratory errors. The three different phases of the TTP - respectively, the pre-analytical, analytical and post-analytical phases - are described in detail and the nature and frequency of errors in each phase explained. For each phase, possible improvements are described and the role of EQA is suggested. Today, EQA principally focuses on the assessment and improvement of the analytical phase. Proposals are made to improve the role of EQA for assessing and improving pre- and post-analytical error as well, by using specific sample material and by automating the reporting of data and laboratory reports to the EQA participants. The principle of the comparison of results of a laboratory with those obtained by the other laboratories is traditionally based on the calculation of "z-scores". An indepth study comparing different techniques has been made, shedding new light on the shortcomings and strong points of the different approaches. We concluded that robust techniques may exhibit weak performance for smaller sample size, while techniques that eliminate outliers before calculating zscores should be recommended. The second Chapter discusses the role of EQA as a tool to assess harmonization between methods. The role of EQA is described, together with the pitfalls and current shortcomings for assessing harmonization. A major problem in assessing standardization between methods is the possible presence of matrix effects in control samples, in which a method-specific bias may appear. Several explanations for matrix effects are mentioned and statistical techniques are described that assist EQA organizers to split up the data in homogeneous peer groups using multivariate statistics. The chapter also reviews several techniques to be used in method comparison studies, and the preference for the use of orthogonal regression is expressed. In addition, an example is given of a method-comparison study for Estradiol and Progesterone, with a novel technique of assessing standardization between various methods, in the presence of matrix effects for a small number of samples. The study also reveals that standardization between various methods is not attained, and that the striving for standardization with standards of higher order may not be satisfactory. Chapter 3 introduces different evaluation techniques that combine information from different samples or parameters: Variance and bias index scores, Mean ranking scores, counts of z- and u-scores, and a long-term analytical Coefficient of Variation. Also, a new and original method is introduced that uses 3 steps to identify outliers in a first step, to find laboratories with exceeding variability in a second, and to identify laboratories with high bias in a third step. Each of the techniques are evaluated and discussed by means of a data set in which accidental outliers, high variability and high bias were induced. In addition, the comparison between the different evaluation methods reveals that distinguishing between variability and bias is a tedious task, and that some long-term analysis methods lack robustness against outliers. Also, it is proven that evaluation techniques summarizing results of different parameters may hide useful information. In addition, the 3-step method is proposed as a method for discerning between errors produced in the pre- or post-analytical phase, and errors that arise from the analytical phase. Chapter 4 applies the 3-step method to data obtained from the Belgian EQA. Data sets from alcohol, flow cytometry, lithium and semen analysis surveys are examined. The method is extended for applicability to heteroscedastic, i.e. unequal residual variability, regression models and demonstrates that it is able to be used in a wide range of surveys. For each of the surveys under consideration, a follow-up is made of the occurrence of accidental mistakes, and the evolution of within-laboratory variability and bias for selected methods. It highlights several conclusions that show a striking similarity for various EQA surveys: an improvement of laboratory performance has been attained over time. The major improvement was a reduction of accidental mistakes. The analytical performance of selected methods, however, did not show an improvement over time. In Chapter 5, some graphical representations of EQA data are explored and a graphical representation of the 3-step method is described. The histogram, normal quantile plot and box plot are described in detail and suggested for providing a quick visual overview of EQA data. Other graphical representations that respond to specific questions are given and discussed as well, like Shewhart charts, Cusum charts and graphical representations to combine variability and bias in one graph. In addition, the 3-step method is graphically explored by means of three distinct graphs. The chapter finishes by suggesting the use of interactive graphs for improving feedback from the EQA organizers to the EQA participants by means of Scalable Vector Graphics. The latter is illustrated with web-accessible examples of long-term evaluation of z-scores and the results of the 3-step method for the data obtained in the Belgian EQA for alcohol determination in blood. In brief, this work describes in a critical and constructive way current statistical methods used in EQA and proposes novel statistical and graphical techniques to help alleviating the future needs of External Quality Assessment programmes. [less ▲]

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See detailImmuno-inflammatory mechanisms in refractory asthma
Manise, Maïté ULiege

Doctoral thesis (2012)

Detailed reference viewed: 46 (9 ULiège)
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See detailContribution à l'étude de la surveillance de la mécanique ventilatoire du nouveau-né ventilé.
RIGO, Vincent ULiege

Doctoral thesis (2012)

Mechanical ventilation, still a major intervention to improve prognosis in newborns, requires careful monitoring of ventilated infants. This monitoring integrates different parameters. Its classical focus ... [more ▼]

Mechanical ventilation, still a major intervention to improve prognosis in newborns, requires careful monitoring of ventilated infants. This monitoring integrates different parameters. Its classical focus is on blood gases and their proxy (pulse oxymetry, transcutaneous oxygen and carbon dioxide content), and also includes physical assessment, thoracic imaging and appraisal of ventilator settings. Use of currently available on-line respiratory mechanics (RM) as displayed by ventilators seems limited given a large apparent variability. As current respiratory support strategies aim to reduce exposure to mechanical ventilation and to decrease ventilator associated lung injuries, additional continuous monitoring tools could benefit neonatal patients. In a review of advanced biomedical devices in use in the neonatal intensive care units and areas where improvement or evaluation is necessary, the National Institute for Child Health and Human Development underlines simple tools for continuous assessment of vital pulmonary functions at the bedside. This research aims at finding solutions to that problem. In a first step, different respiratory mechanics parameters (dynamic compliance –Cdyn, dynamic resistance –Rdyn, tidal volume –VT and the overdistension parameter C20/C) are obtained from ventilatory recordings of newborns under respiratory support with the most commonly used neonatal ventilator to evaluate their clinical relevance. Those data present a high variability and therefore lack precision. It is possible to mathematically decrease this variability by using parameters averaged over a few minutes and to obtain reproducible results. Continuous pressure, flow and volume data from the ventilator allow construction of pressure-volume, pressure-flow and flow-volume loops. From those loops, Cdyn, Rdyn and VT can be computed by the Mead-Whittenberger method. Those values when derived from respiratory cycles with good appearance significantly differ from ventilator values. Given the lack of precision of ventilator derived respiratory mechanics data, a new strategy is developed to obtain those parameters only from optimal looking respiratory cycles. A new software is designed to reconstruct waves and loops from the ventilator continuous recordings. This software individualises respiratory cycles and compute Cdyn and Rdyn (least mean square method), VT and C20/C. Using 10 sets of two recordings (one in Synchronized Intermittent Mandatory Ventilation and one in Assist/Control ventilatory modes), visual evaluation of 11274 respiratory cycles selects 4847 cycles considered optimal looking. Those assisted cycles present no or minimal leak, good hysteresis of the pressure-volume loop, and no abnormalities of the flow curves. The coefficients of variation of the respiratory mechanics parameters obtained with this method are significantly decreased, by 25-27% from the ventilator values for Rdyn, Cdyn and C20/C, and by 60% for VT. This increase in parameters precision is associated with an improved capacity to discriminate different values. Analysis of discordant values between ventilator and optimal respiratory cycles is relevant. In A/C mode, the VTs from the selected respiratory cycles are lower than values reported by the ventilator, suggesting that currently available VTs give incomplete information for adjustment of ventilator settings. In SIMV mode, the weak correlation between Cdyn from both methods leads to question the relevance of ventilator informations. The important scattering of ventilator C20/Cs out of classical values, and the absence of correlation with values from selected respiratory cycles demonstrate the lack of validity of ventilator C20/Cs. Overall, the results suggest that the use of data derived from selected respiratory cycles could underlie the conception of RM monitoring tools to support ventilatory management. To avoid the heavy workload associated with visual respiratory cycles’ selection, the software is improved to automatically identify optimal cycles. The positive predictive values and specificity of this selection are high. Respiratory mechanics parameters from cycles selected automatically are very concordant with those from visually selected cycles. The last step of this work assesses the software potential with analysis of 21 recordings from various clinical situations. The discriminating power of automatically selected respiratory cycles’ parameters is tested in an extended population. Trending abilities of those parameters are evaluated. Analyses of respiratory mechanics parameters derived from automatically selected cycles are able to demonstrate differences of 4.6-7.1% and more between parameters from two 10min recordings. Averaging data over 3-7min allows to determine a 10% difference. Parameters averaged over 10min allow detection of 10% changes in most patients. Those results should allow building trend curves with clinically and statistically significant informations. In conclusion, the continuous respiratory mechanics analysis software developed and evaluated in this work should give precise informations on the dynamic evolution of RM parameters. Functions integrated in the last version of the software give immediate research opportunities, and should lead to clinical application in a very near future. Those parameters could then complete current informations integrated in ventilatory management. [less ▲]

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See detailContribution à l’optimalisation du support nutritionnel et de la croissance des prématurés de très faible poids à la naissance
SENTERRE, Thibault ULiege

Doctoral thesis (2012)

Postnatal growth restriction (PNGR) is a common finding during neonatal hospitalization in very low birth weight (VLBW) infants. Insufficient nutritional support during the first weeks of life is ... [more ▼]

Postnatal growth restriction (PNGR) is a common finding during neonatal hospitalization in very low birth weight (VLBW) infants. Insufficient nutritional support during the first weeks of life is responsible of major cumulative protein and energy deficit that has been considered as malnutrition. VLBW infants are frequently described small-for-gestational age (SGA) at discharge. The insufficient nutritional support is the primary aetiology of the PNGR observed in VLBW infants. Furthermore, both insufficient nutritional intakes and poor growth have been associated with adverse short and long-term outcomes. Particularly, they impair neurodevelopment and favor disorders in adulthood like obesity, type 2 diabetes, hypertension and cardiovascular diseases. Despite the immaturity of VLBW infants, some authors have proposed to increased nutritional intakes from birth onwards and consider this early ‘‘aggressive’’ nutrition as more optimal. This concept has been translated in the recent recommendations that advocate a minimum of 40 kcal/kg/day and 2.0 g/kg/day of protein from the first day of life that need to be increased to 120 kcal/kg/day and 3.8 g/kg/day of protein by the end of the first week of life. A significant variation has been observed regarding nutritional practices among neonatal intensive care units with many studies still reporting insufficient postnatal nutritional intakes and severe PNGR. Some authors have questioned the feasibility and the adequacy of current nutritional recommendations. Indeed, there are still some concerns that increased nutritional intakes may disturb infant’s condition. Common fears include hyperglycemia, uremia, metabolic acidosis, hyperammoniemia and necrotizing enterocolitis. The aim of this study was to evaluate postnatal growth, cumulative nutritional deficit and metabolic tolerance after optimizing our nutritional policy to recent recommendations. The study is a prospective, observational, non interventional, and single-center cohort study in VLBW infants <1250g. All consecutive infants admitted in the NICU during a 2-year period were included in the study (N=102). Severely ill infants and infants with congenital anomalies were not excluded from the analysis. This study is the first to demonstrate nutritional intakes in the range of current recommendations. It suggests that it is possible to optimize nutritional intakes routinely in real clinical practice. The use of an adequate standardized ready-to-use parenteral solution appears to contribute to improve the early nutritional supply. Optimizing the energy and protein intakes significantly reduced the cumulative nutritional deficit, even in extremely preterm infants <28 weeks’ gestational age. In the majority of infants, PNGR could even be prevented. In our cohort, only 6% of appropriate-for-gestational age infants became SGA at discharge. Moreover, 20% of SGA infants became appropriate for gestational age at discharge. No major metabolic disturbances were observed and, even more, biological perturbations seem to decline compared to most recent studies. Additionally, we evaluate the first commercially manufactured parenteral nutrition developed for preterm infants. Theses studies confirm that the first week of life is a critical period to promote growth. This study is an important step in neonatal intensive care. It demonstrates that malnutrition may be avoided in VLBW infants and that postnatal growth may be enhanced with little restriction by the time of discharge. It is an important contribution to the development of VLBW infants. [less ▲]

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See detailMacrolide and lincosamide resistance patterns in invasive and colonizing group B streptococcus isolated in Belgium
DESCY, Julie ULiege

Master's dissertation (2012)

Increase of erythromycin and clindamycin resistance among group B Streptococcus (GBS) have been reported worldwilde. Therefore phenotypical and molecular surveillance of macrolides and lincosamides ... [more ▼]

Increase of erythromycin and clindamycin resistance among group B Streptococcus (GBS) have been reported worldwilde. Therefore phenotypical and molecular surveillance of macrolides and lincosamides resistance patterns in Belgium has been conducted. Antimicrobial susceptilities to erythromycin and clindamycin were determined by Etest® (EUCAST interpretive criteria) on 275 clinical isolates (N1) obtained from the Belgian surveillance for invasive GBS disease in newborns and adults during 2008 to 2011 and on 53 recto-vaginal colonization in pregnant women (N2) in 2010. Inducible and constitutive resistance to clindamycin were assessed by a double-disk diffusion test. The presence of genes encoding RNA methylases (erm) and efflux pumps (mef) was confirmed by PCR. Of the 328 GBS isolates, 109 (33,2%) were resistant to erythromycin. Among these isolates, 102 (93,6%) exhibited the MLS phenotype (resistant to erythromycin and clindamycin); the M phenotype (resistant to erythromycin and susceptible to clindamycin) was expressed by 7 (6,4%) of the isolates; one isolate presented a L phenotype (susceptible to erythromycin and resistant to clindalycin). For cMLS, the most common genotype was ermB (65%) (P <0,05) followed by ermTR (30%) and ermB+ermTR (5%). All iMLS isolates harbored an ermTR gene except 3 (2 with ermB, 1 with both ermB and ermTR); and all M phenotypes were positive for mefA/B gene. In Belgium, by year 2010, prevalence of macrolide and lincosamide resistance in GBS exceed 30%, with a predominance of MLS phenotypes (target-site modification). Resistance surveillance is mandatory to guide prophylaxis and treatment of serious GBS infections but also to identify newly acquired resistance mechanisms such as the L phenotype. [less ▲]

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See detailAnalytical strategies for the detection of counterfeit erectile dysfunction drugs
Sacré, Pierre-Yves ULiege

Doctoral thesis (2011)

Since the late eighties, when it was first mentioned, the worldwide phenomenon of pharmaceutical counterfeiting is growing. Belgian customs often encounter presumed counterfeited medical products in ... [more ▼]

Since the late eighties, when it was first mentioned, the worldwide phenomenon of pharmaceutical counterfeiting is growing. Belgian customs often encounter presumed counterfeited medical products in Belgian airports and ports because of their central position in Europe and their importance in the transit of goods. Further and deeper analyses are required to assess the counterfeit character of these goods and to provide a scientific basis for the eventual legal procedure. As reference laboratory for the federal agency for medicines and health products (FAMHP), the Scientific Institute of Public Health (IPH) frequently analyses illegal and counterfeit pharmaceutical preparations. The present research project was started with the objective of evaluating several existing methods and developing new analytical methods to detect counterfeit erectile dysfunction drugs. This thesis is focused on the analysis of illegal samples of phosphodiesterase type 5 inhibitors (PDE5-i) containing drugs because these are the most counterfeited pharmaceutical specialities in Belgium. The research was divided into a spectroscopic and a chromatographic part: Infrared based spectroscopies have already demonstrated their ability to detect counterfeit drugs. The first part of the study evaluates the capacity of each technique (mid-infrared (mid-IR), near-infrared (NIR) and Raman spectroscopy) separately and their combinations to discriminate genuine from illegal tablets. Then, the Classification And Regression Trees (CART) algorithm has been used to classify the different samples following the classification system of the Dutch National Institute for Public Health and the Environment (RIVM). The second spectroscopic approach used Raman microspectroscopy mapping to detect counterfeited Viagra®. This technique allows the detection of different compounds according to their Raman spectrum but also the study of the distribution of a selected ingredient among the core of a tablet. The chromatographic part consists of the development and validation of a new Ultra High Pressure Liquid Chromatography method coupled with a UV diode array detector (UHPLC-DAD) and compatible with mass spectrometry (MS) to detect and quantify the three authorised phosphodiesterase type 5 inhibitors (sildenafil, tadalafil and vardenafil) and five of their analogues in illegal pharmaceutical preparations. This method has been validated between +/- 5% acceptance limits using the total error approach and has been compared to the official Viagra® assay method. The ability of HPLC-UV impurity fingerprints to detect illegal samples and to predict whether a new unknown sample is genuine has also been evaluated. The developed analytical methods may be included in a general approach to detect counterfeit drugs containing PDE5-i. This generic approach may also be used to detect other types of counterfeited drugs but should therefore be adapted for each type of medicine. [less ▲]

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See detailImplication des cellules Natural Killer (NK) dans le développement des lésions associées à l'infection par les papillomavirus humains (HPV)
Renoux, Virginie ULiege

Doctoral thesis (2011)

Persistent infections with high-risk papillomavirus (HPV) are associated with more than 25% of cancers induced by infectious agents. Nevertheless, the two vaccines preventing HPV infection have no ... [more ▼]

Persistent infections with high-risk papillomavirus (HPV) are associated with more than 25% of cancers induced by infectious agents. Nevertheless, the two vaccines preventing HPV infection have no therapeutic efficacy and it has been estimated that there will be no measurable decline of HPV-associated tumours before 2040. The immune system is able to control, at least partially, HPV infection and subsequent tumour development. Around 90% of HPV-infected women will clear the virus within two years, but the immune effectors responsible for this viral clearance are unknown. Hence, the aim of this study was to determine if Natural Killer (NK) cells could play a role in the immune response against HPV infection and related cancers. The first part of this work was focused on the in vitro interaction of NK cells with L1 and L1L2 Virus Like Particles (VLP) of HPV16. We observed that, in the presence of HPV-VLP, NK cells displayed a higher cytotoxic activity against HPV+ cells by increasing the exocytosis of their cytotoxic granules and by secreting TNF-α and IFN-γ. NK cell activation was correlated with a fast entry of HPV-VLP by macropinocytosis and we determined that cell surface CD16 expression was necessary for HPV internalization, but also for degranulation and cytokine production. In the second part, to understand the molecular mechanisms of HPV-VLP stimulation, we investigated the signalling pathways operating in NK cells to trigger their cytotoxic activity in the presence of viral particles. We observed that the MAP kinases ERK and p38 were phosphorylated in the presence of both L1 and L1L2 HPV-VLP. Using specific inhibitors, we demonstrated that phosphorylation of these MAPK was required for degranulation and cytokine secretion by NK cells in the presence of VLP. In conclusion, NK cell activity could be an important player in the immune response contributing to viral clearance and to regression of HPV-induced cervical lesions. [less ▲]

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See detailResidual Stress in Veneering Ceramic
MAINJOT, Amélie ULiege

Doctoral thesis (2011)

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See detailModulation des points de contrôle du cycle cellulaire par la protéine Tax du virus T-lymphotrope humain de type 1 (HTLV-1) : vers une nouvelle approche thérapeutique
Carpentier, Alexandre ULiege

Master's dissertation (2011)

HTLV-1 infects approximately 20 million people worldwide and causes several diseases. This virus is responsible for the adult T-cell leukemia (ATL) and for a chronic neuropathology (TSP/HAM). There is ... [more ▼]

HTLV-1 infects approximately 20 million people worldwide and causes several diseases. This virus is responsible for the adult T-cell leukemia (ATL) and for a chronic neuropathology (TSP/HAM). There is currently no satisfactory treatment for these diseases. Among the proteins encoded by HTLV-1, Tax appears to play an important role in the mechanisms leading to pathogenicity. In this work, we used confocal microscopy and flow cytometry to study the interactions between Tax and the DNA damage response (DDR) as well as the associated DNA repair pathways. We demonstrated that expression of Tax results in arrest of the cell cycle and concomitantly in activation of the ATM-Chk2-p53 axis of the DDR. We showed the involvement of p53 and Chk2 in G1 and S/G2 arrests, respectively. For the sake of biological relevance, we also showed that HTLV-1 infected cells do not encounter any arrest during their proliferation. It seems that these cells are adapted to the p53/Chk2 checkpoints and retain repair pathway(s) controlled by Chk1 and BRCA1. Our results indicate that the Chk1-related trans-lesion synthesis is one of the alternative repair pathways occurring in infected cells. Inhibition of this pathway could be a new therapeutic approach for ATL. [less ▲]

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See detailREGULATION DE L'EXPRESSION ET DE LA REPLICATION DU VIRUS T-LYMPHOTROPE HUMAIN DE TYPE I (HTLV-1) PAR LE COMPLEXE MINICHROMOSOME MAINTENANCE 2-7 (MCM2-7)
Barez, Pierre-Yves ULiege

Master's dissertation (2011)

First human retrovirus discovered, HTLV-1 infects approximately 20 million individuals worldwide. HTLV-1 is the etiological agent of adult T-cell leukemia and a neurodegenerative disorder called HAM/TSP ... [more ▼]

First human retrovirus discovered, HTLV-1 infects approximately 20 million individuals worldwide. HTLV-1 is the etiological agent of adult T-cell leukemia and a neurodegenerative disorder called HAM/TSP (HTLV-1 associated myelopathy/Tropical spastic paraparesis). The MCM2-7 complex seems to play a key role in the biology of viruses, such as EBV (Epstein-Barr virus), KSHV (Kaposi’s sarcoma associated virus) or Influenza. This is also the case for HTLV-1 virus because we revealed the recruitment of MCM2-7 onto the viral promoter. The role of this interaction does not pertain to viral replication but is involved in transcriptional regulation. In fact, overexpression of MCM3 increases Tax transactivation activity dependently on Tax/MCM3 interaction and MCM3 carboxy-terminal domain. Finally, our observations indicate that MCM3 is likely required for Tax nuclear shuttling. This work thus gives insights into new mechanisms by which Tax ensures the viral persistence and leads to the development of HTLV-1 associated diseases. [less ▲]

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See detailRole de l'ADN endogène et d'Interferon Response Factor-3 dans l'induction des réponses immunitaires médiées par les lymphocytes T auxiliaires de type 2.
Marichal, Thomas ULiege

Doctoral thesis (2011)

Adaptative type 2 helper T cell (Th2) responses represent an important component of adaptative immunity and are implicated in various (patho)physiological processes such as allergic diseases, host defense ... [more ▼]

Adaptative type 2 helper T cell (Th2) responses represent an important component of adaptative immunity and are implicated in various (patho)physiological processes such as allergic diseases, host defense against helminths and artificially adjuvanted vaccination. Induction of adaptative T responses occurs with the help of innate immune cells, especially dendritic cells (DCs). These DCs make the link between innate and adaptative immunity by taking up antigens in peripheral tissues, migrating to lymphoïd organs and presenting antigens to T lymphocytes. Direct or indirect activation of these cells depends on the interaction between exogenous or endogenous danger signals and conserved innate immune receptors, mainly represented by Pattern Recognition Receptors (PRRs). Despite the importance of Th2 responses, the innate immune mechanisms leading to their activation remain partially unknown. For this reason, we have been interested in immune mechanisms underlying the induction of Th2 responses in two major Th2-dependent immunological processes : airway allergy and vaccination with aluminium hydroxides (alum). Airway allergy, of which the most severe manifestation is allergic ashma, is a constantly increasing disease in developped countries. It appears clearly that the stimulation of PRRs by allergens or immunostimulatory molecules plays a key role in the pathophysiology of airway allergy. In addition, PRRs transduce the signal though a limited number of signaling pathways and the role of Interferon Response Factor (IRF)-3 and IRF-7, two important transcription factors downstream of various PRRs, in the pathogenesis of allergic asthma, remains unknown. Therefore, we have investigated their potentiel implication in this disease. We have discovered that IRF-3, but not IRF-7, plays an essential role in allergic airway sensitization against house dust mite antigens, the main allergen source in humans. We have further demonstrated that IRF-3 was intrinsically required in lung DCs for their proallergic function. The IRF-3-dependent effects were independent of type I interferons, the main target genes of IRF-3. Alum is the most widely used artificial adjuvant in human and animal vaccination. Yet, little is known about its mechanism of action, in particular regarding the nature of signals and signaling pathways promoting Th2 responses. We have postulated that alum, like any other efficient adjuvant, must be expected to stimulate innate immunity. On one hand, alum does not contain any molecular pattern that is recognized by PRRs and, on the other hand, alum is known to be cytotoxic. Therefore, we hypothetised that alum-induced endogenous danger signals could play a role in its adjuvant activity. Here, we report that alum induces cell death and subsequent DNA release. This DNA acts as a endogenous immunostimulatory signal relaying alum adjuvant activity on adaptative responses. Furthermore, we propose that host DNA differentially regulates IgG1 and IgE production following alum immunization. Indeed, an IRF-3-dependent DNA signaling pathway plays a role in the activation of inflammatory DCs, the subsequent induction of Th2 response and IgE isotype switching, whereas DNA also induces IgG1 production through IRF-3- independent mechanisms. The finding that host cell endogenous DNA is a damageassociated molecular pattern relaying alum adjuvant activity may thus help in the comprehension of the mechanisms of action of current vaccines and in the design of novel adjuvants. In conclusion, this work has identified a previously unappreciated role for IRF-3, a transcription factor downstream of various PRRs primarily implicated in antiviral responses, in two Th2-dependent immunological processes: allergic asthma and alum-based vaccination. In these models, we have shown that IRF-3 was intrinsically required in professional antigen presenting cells, namely DCs, in order to activate them, a precondition for the priming of adaptative Th2 responses. In addition, we also discovered that host DNA released upon alum treatment acts as an endogenous danger signal mediating the adjuvant activity of alum. [less ▲]

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See detailMéthodes d'identification des paramètres dans un modèle du système cardiovasculaire
Pironet, Antoine ULiege

Master's dissertation (2011)

Les dysfonctions du système cardiovasculaire sont une origine majeure des admissions dans les unités de soins intensifs. Dans ces unités, les patients sont très instables et les cliniciens disposent d’un ... [more ▼]

Les dysfonctions du système cardiovasculaire sont une origine majeure des admissions dans les unités de soins intensifs. Dans ces unités, les patients sont très instables et les cliniciens disposent d’un nombre limité de mesures pour prendre rapidement les bonnes décisions. L’utilisation de modèles patient-spécifiques pour guider les clini- ciens offre alors des perspectives réelles. Un modèle simple à six compartiments du système cardiovasculaire a été développé par Smith et al. et une méthode d’identification des paramètres de ce modèle a été développée par Revie et al. Ce modèle a été étendu en y ajoutant deux compartiments représentant les oreillettes, dont le comportement est décrit par un modèle inspiré de travaux existants. Une méthode d’identification similaire à celle utilisée par Revie et al. a été développée pour les nouveaux paramètres. Pour ne pas devoir recourir à la pression auriculaire, difficile à mesurer expérimentalement, une méthode permettant de déduire la pression auriculaire à partir de la pression ventriculaire a également été introduite. L’application du modèle étendu et de la méthode d’identification correspondante à des données expérimentales montre que l’introduction des oreillettes dans le modèle ne cause pas de trop grandes erreurs et que la méthode d’estimation de la pression auriculaire est correcte. En conclusion, la valeur ajoutée de la méthode développée dans ce travail est grande, puisqu’elle permet d’obtenir des informations supplémentaires sans introduire de grandes erreurs et sans imposer le besoin de recourir à de nouvelles mesures. [less ▲]

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See detailEpigenetic Therapy of Lung Cancers: Anti-tumoral effect of valproate on small cell lung cancer
Hubaux, Roland ULiege

Doctoral thesis (2011)

Lung cancer is the leading cause of cancer-related death worldwide. Among lung carcinomas, the outcome of small cell lung carcinoma (SCLC) patients is the poorest of any histological subtype with five ... [more ▼]

Lung cancer is the leading cause of cancer-related death worldwide. Among lung carcinomas, the outcome of small cell lung carcinoma (SCLC) patients is the poorest of any histological subtype with five-year survival rate of less than 20 and 5 % for limited and extensive stage respectively. Based on increasing evidence that inhibitors of histones deacetylases (HDAC) have anticancer properties, the goal of this study was to evaluate the ability of valproate (VPA) to improve efficacy of chemotherapeutic regimen in SCLC. We show that VPA directly induces apoptosis of SCLC cell lines at concentrations relevant for clinical uses. Furthermore, VPA synergizes with two chemotherapeutic regimen used in first (cisplatin + etoposide) and second line (cyclophosphamid + vindesine + doxorubicin) treatments. Both mitochondrial and death receptor pathways are involved in VPA-induced apoptosis. Although VPA promotes production of reactive oxygen species, free radical scavenger N-acetylcystein is not sufficient to inhibit apoptosis. As expected, VPA triggers hyperacetylation of histone H3 and increases expression of p21. VPA reduces levels of BclxL, induces cleavage of Bid, translocation of Bax to mitochondria, release of cytochrome c into cytosol and phosphorylation of Erk and H2AX. Transcriptomic analyses by microarrays and quantitative RT-PCR have underscored a series of genes candidates potentially implicated into sensitivity of SCLC to VPA. Among these, the Fzd7 receptor of the WNT pathway is essential for VPA proapoptotic activity. Efficiency of VPA combined to first and second line chemotherapeutic agents is supported by preclinical models of SCLC cells engrafted into SCID mice. The second line combination is presently tested in a clinical trial with patients presenting with refractory or relapsing small cell lung cancer (protocol 01081 at http://www.elcwp.org). [less ▲]

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