Multiorgan dysfunction syndrom is the major driving pathophysiological mechanism of morbidity and mortality in critically ill patients. Gastrointestinal dysfunction usually develops as a result critical illness and it is believed to play a key role in the development and progression of multiple organ dysfunction. Moreover, any primary disorder of the gastrointestinal tract, if severe enough, can lead to a critical state and secondary multiorgan dyfunction. Despite intensive experimental and clinical research, reliable tools for monitoring and evaluation of the severity of gastrointestinal dysfunction remain unknown. In the same line, therapy of this complex pathology remains largely supportive. The aim of this thesis was first to explain the severity of the most common and most serious nosocomial infection of the digestive tract, second to elucidate the safety and effectiveness of the endoscopic dual enteral probe insertion in ventilated critically ill patients, and, third to evaluate new diagnostic tools of the gastrointestinal dysfunction. Finally, we present an ongoing project aimed at investigating esophageal dysfunction in mechanically ventilated critically ill patients.

Les canalopathies cardiaques congénitales constituent la principale hypothèse diagnostique dans les cas de mort subite inexpliquée chez les sujets de moins de 35 ans. Notre travail a eu pour objectif demettre au point une stratégie de détection post-mortem des mutations sur les gènes connus pour être impliqués dans les canalopathies cardiaques, applicable en routine, à partir de la principale source d’ADN post-mortem disponible en France à savoir les prélèvements fixés au formol et inclus en paraffine (FFIP). A partir d’une cohorte de 12 cas, deux techniques de détection de variants génétiques ont été évaluées, une technique de criblage par l’analyse des courbes de fusion haute résolution et une technique de génotypage par spectrométrie de masse MALDI-TOF, respectivement sur le gène KCNQ1 et le gène RyR2. Quelle que soit la technique utilisée, il n’est pas possible de s’affranchir du séquençage de type Sanger afin d’explorer les séquences d’intérêts qui n’ont pu être optimisées avec l’une ou l’autre des méthodes à la fois sur les prélèvements congelés et FFIP. L’arrivée des séquenceurs de nouvelles générations ouvrent ainsi de nouvelles perspectives dans ce domaine. / The congenital cardiac channelopathies constitute the principal diagnostic hypothesis in autopsynegative sudden unexplained death concerning people younger than 35 years old. The present study aimed to develop a strategy of mutations detection on known genes implicated in the cardiac channelopathies. This strategy of mutations detection had to be applicable to routine and has been studied on formalin-fixed and paraffin-embedded (FFPE) tissues which are the principal DNA source available in France. On a cohort of 12 cases, two technique of sequence variants detection wereevaluated: the screening method of High Resolution Melt and the genotyping method based on a MALDI-TOF mass spectrometry, respectively on KCNQ1 and RyR2 genes. Whatever the technique, there is a necessity of resorting to the Sanger sequencing to explore the sequence of interest none optimized with one or the other technology both on FFEP and frozen tissues. That’s why the next generation sequencing method should open new perspectives in the post-mortem diagnostic of cardiac channelopathies.

No description available.

L’utilisation intensive des produits phytosanitaires, en particulier les insecticides, provoque des effets indésirables sur les organismes vivants et leur environnement. Mon travail de thèse a consisté à évaluer l’effet de deux insecticides chez un insecte modèle la drosophile. Une première étude concernait l’effet d’un néonicotinoïde, l’imidaclopride. Nous avons pu montrer que l’exposition chronique à des doses sublétales de cet insecticide perturbe la fonction de reproduction chez la drosophile. D’autre part, une exposition aiguë à l’imidaclopride a mis en évidence une résistance chez les femelles d’une souche de drosophile dite ``des champs´´. Deux mécanismes différents ont été mis en évidence dans la résistance à l’imidaclopride de cette souche. Le premier concerne la sous expression d’une sous-unité (D1) du récepteur nicotinique à l’acétylcholine, cible de l’imidaclopride. Le deuxième concerne l’implication des glutathion S-transférases, enzymes de détoxification, dans le métabolisme de l’imidaclopride. Ces études montrent que les insecticides peuvent avoir en plus des effets sur les insectes ravageurs, des effets néfastes sur des organismes non cibles. La deuxième étude avait pour but de modéliser chez la drosophile, l’impact d’un organochloré, la dieldrine, potentiellement impliquée dans la maladie de Parkinson chez l’homme. L’exposition à cet insecticide conduit à une dégénérescence des neurones dopaminergiques ainsi qu’une perturbation de la structure de régions particulières du cerveau. Nous avons également montré des altérations du métabolisme et l’implication de processus épigénétiques dans la neurodégénérescence induite par la dieldrine. Au cours de ce travail, nous avons pu montrer l’intérêt de nouvelles méthodes comme l’Imagerie par Résonance Magnétique (IRM) ou le High Resolution Magic Angle Spinning (HRMAS) dans ce type d’étude. / Pesticides have been used extensively and induce harmful effects on organisms and their environment. The aim of my PhD work was to investigate the effects of two insecticides by using Drosophila as a model. The first study concerns the effect of a neonicotinoid, imidacloprid. The results obtained have shown that a chronic exposure at sublethal doses of this insecticide affects reproduction in flies. Moreover, acute exposure at high doses has pointed out a resistance phenomenon in females of a field strain. We have shown that two mechanisms are implicated: (i) low expression of a subunit of a nicotinic acetylcholine receptor that is the target of imidaclopride and (ii) role of glutathione S-transférases, detoxication enzymes, in imidaclopride metabolism. These results highlight impact of insecticides, in particular imidaclopride, on non target organisms. The aim of the second study was to characterize in Drosophila, effects of an organochlorine, dieldrin, potentially implicated in the etiology of Parkinson’s disease in humans. Dieldrin exposure at low doses promotes neurodegeneration of dopaminergic neurons and alters structures of particular regions of the brain. Disruption of metabolism is also induced after exposition to dieldrin. In addition, we have shown that epigenetic processes are implicated in neurodegenration induced by dieldrin. This work show advantages of new techniques such as Magnetic Resonance Imaging (MRI) and High Reslution Magic Angle Spinning in this kind of study.

In the past decades, numerous single-molecule techniques have been developed to investigate individual bio-molecules and cellular machines. While a lot is known about the structure, localization, and interaction partners of such molecules, much less is known about their mechanical properties. To investigate the weak, non-covalent interactions that give rise to the mechanics of and between proteins, an instrument capable of resolving sub-nanometer displacements and piconewton forces is necessary. One of the most prominent biophysical tool with such capabilities is an optical tweezers. Optical tweezers is a non-invasive all-optical technique in which typically a dielectric microsphere is held by a tightly focused laser beam. This microsphere acts like a microscopic, three-dimensional spring and is used as a handle to study the biological molecule of interest. By interferometric detection methods, the resolution of optical tweezers can be in the picometer range on millisecond time scales. However, on a time scale of seconds—at which many biological reactions take place—instrumental noise such as thermal drift often limits the resolution to a few nanometers. Such a resolution is insufficient to resolve, for example, the ångstrom-level, stepwise translocation of DNA-binding enzymes corresponding to distances between single basepairs of their substrate. To reduce drift and noise, differential measurements, feedback-based drift stabilization techniques, and ‘levitated’ experiments have been developed. Such methods have the drawback of complicated and expensive experimental equipment often coupled to a reduced throughput of experiments due to a complex and serial assembly of the molecular components of the experiments. We developed a high-resolution optical tweezers apparatus capable of resolving distances on the ångstrom-level over a time range of milliseconds to 10s of seconds in surface-coupled assays. Surface-coupled assays allow for a higher throughput because the molecular components are assembled in a parallel fashion on many probes. The high resolution was a collective result of a number of simple, easy-to-implement, and cost-efficient noise reduction solutions. In particular, we reduced thermal drift by implementing a temperature feedback system with millikelvin precision—a convenient solution for biological experiments since it minimizes drift in addition to enabling the control and stabilization of the experiment’s temperature. Furthermore, we found that expanding the laser beam to a size smaller than the objective’s exit pupil optimized the amount of laser power utilized in generating the trapping forces. With lower powers, biological samples are less susceptible to photo-damage or, vice versa, with the same laser power, higher trapping forces can be achieved. With motorized and automated procedures, our instrument is optimized for high-resolution, high-throughput surface-coupled experiments probing the mechanics of individual biomolecules. In the future, the combination of this setup with single-molecule fluorescence, super-resolution microscopy or torque detection will open up new possibilities for investigating the nanomechanics of biomolecules.

Multiorgan dysfunction syndrom is the major driving pathophysiological mechanism of morbidity and mortality in critically ill patients. Gastrointestinal dysfunction usually develops as a result critical illness and it is believed to play a key role in the development and progression of multiple organ dysfunction. Moreover, any primary disorder of the gastrointestinal tract, if severe enough, can lead to a critical state and secondary multiorgan dyfunction. Despite intensive experimental and clinical research, reliable tools for monitoring and evaluation of the severity of gastrointestinal dysfunction remain unknown. In the same line, therapy of this complex pathology remains largely supportive. The aim of this thesis was first to explain the severity of the most common and most serious nosocomial infection of the digestive tract, second to elucidate the safety and effectiveness of the endoscopic dual enteral probe insertion in ventilated critically ill patients, and, third to evaluate new diagnostic tools of the gastrointestinal dysfunction. Finally, we present an ongoing project aimed at investigating esophageal dysfunction in mechanically ventilated critically ill patients.

Much of the current research into the processing and storage of carbon (C) in small lakes has focused on arctic and boreal lake systems, due to their global abundance. However this has led to an imbalance in the interpretation of lake functioning. Oligotrophic lakes are prevalent in the arctic and boreal zone, but are typically net heterotrophic due to loading of catchment-derived dissolved organic carbon (DOC) which alters their metabolic balance. In comparison, temperate lake systems tend to be more nutrient rich, typically due to anthropogenic activity, and would therefore be expected to exhibit the signs of net autotrophy, as a result of higher rates of gross primary production (GPP) and lower rates of catchment-derived DOC potentially subsidising respiration (R). In order to test the hypothesis that temperate, eutrophic lakes are net autotrophic (GPP > R) on an annual basis the C-dynamics of Rostherne Mere (maximum depth, zm, 31 m) and Tatton Mere (zm = 11 m), two monomictic Cheshire-Shropshire meres, were quantified over an 18 months period from 2010 2012. This monitoring study used high-resolution (hourly) oxygen (O2) sonde measurements, combined with high-resolution data from an automated on-lake monitoring buoy at Rostherne Mere (as part of the national UKLEON lake network) to calculate rates of epilimnion C-fixation. For both lakes, sediment traps were also used to determine water column C-flux and sediment core data to establish C-burial efficiency of these strongly stratifying lakes. Water column profiles of dissolved O2 and CO2 was also measured at 2 4 weekly intervals across both lakes. Particular attention was focused on: i) the long term C-storage of eutrophic, monomictic lakes; ii) up-scaling C-accumulation estimates from these two meres to the Cheshire-Shropshire meres region and all UK eutrophic waters; and iii) methodological sensitivity for estimating C-fixation, flux and burial efficiency and upscaling C-accumulation estimates. The results show that both lakes are net autotrophic on an annual basis, on average fixing 121 ± 2 g C m-2 yr-1 and sequestering 68 ± 4 g C m-2 yr-1, a C-burial efficiency of ~60%. If up-scaled to the Cheshire-Shropshire meres region, annual C-accumulation was estimated to be 506 ± 32 t C yr-1 or 0.05 ± 0.001 Mt C since 1900. From this, it was estimated that UK eutrophic waters could be sequestering 0.12 ± 0.01 Mt C yr-1 or 13.3 ± 0.2 Mt C since 1900. Annual UK CO2 emissions are ~128.85 Mt C yr-1, therefore UK eutrophic waters currently offset 0.09% of yearly UK CO2 emissions. Despite the finding that eutrophic, stratifying lakes have high C-fixation and sequestration values, lakes in other areas of the globe such as the arctic and boreal zones are typically a more important long term C-sink as they are far more abundant within the landscape and local soils are typically very poor within low C retention rates. Further investigation is needed into how lakes function on a regional and national scale, the importance of lake type and number when up-scaling C accumulation estimates and the potential impact on future C accumulation as a result of a changing environment and supra-regional policies in areas such as Europe.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The operator interface to a modern radar, sonar or weapons system trainer (WST) is typically one or more high-resolution video displays driven by PC’s or other workstations. The training system used to instruct and qualify operators for this type of mission critical application should be capable of recording RGB video data to a fine level of detail. Similarly, ground stations for Research, Development, Test and Evaluation (RDT&E) and Operational Test & Evaluation (OT&E) applications often utilize high-resolution workstation screens to display critical test data. And often, these workstation screens are located in mobile vans, on aircraft, or are otherwise remote from test conductors who need access to the same screen data. This paper presents a solution for the efficient digitization, storage, replay, and transmission of the data displayed on the high-resolution workstation screens commonly found in these types of training system applications.

Much research effort has been devoted to producing algorithms that contribute directly or indirectly to the extraction of 3D information from a wide variety of types of scenes and conditions of image capture. The research work presented in this thesis is aimed at three distinct applications in this area: interactively extracting 3D points from a pair of uncalibrated images in a flexible way; finding corresponding points automatically in high resolution images, particularly those of archaeological scenes captured from a freely moving light aircraft; and improving a correlation approach to dense disparity mapping leading to 3D surface reconstructions. The fundamental concepts required to describe the principles of stereo vision, the camera models, and the epipolar geometry described by the fundamental matrix are introduced, followed by a detailed literature review of existing methods. An interactive system for viewing a scene via a monochrome or colour anaglyph is presented which allows the user to choose the level of compromise between amount of colour and ghosting perceived by controlling colour saturation, and to choose the depth plane of interest. An improved method of extracting 3D coordinates from disparity values when there is significant error is presented. Interactive methods, while very flexible, require significant effort from the user finding and fusing corresponding points and the thesis continues by presenting several variants of existing scale invariant feature transform methods to automatically find correspondences in uncalibrated high resolution aerial images with improved speed and memory requirements. In addition, a contribution to estimating lens distortion correction by a Levenberg Marquard based method is presented; generating data strings for straight lines which are essential input for estimating lens distortion correction. The remainder of the thesis presents correlation based methods for generating dense disparity maps based on single and multiple image rectifications using sets of automatically found correspondences and demonstrates improvements obtained using the latter method. Some example views of point clouds for 3D surfaces produced from pairs of uncalibrated images using the methods presented in the thesis are included.

Involviert in Netzwerke für das episodische Gedächtnis sowie als Bestandteil des Hypothalamus und des limbischen Systems stellen sich die im Zwischenhirn gelegenen Mamillarkörper als Zielstruktur im Kontext affektiver Störungen dar. Bislang waren die Mamillarkörper diesbezüglich lediglich in einer postmortem durchgeführten Studie Gegenstand der Forschung; es liegen keine Untersuchungen mit Hilfe der 7 Tesla-Magnetresonanztomografie vor. Um diese neuen Möglichkeiten der in vivo-Volumetrie im Submillimeterbereich auszuschöpfen, wurde auf Grundlage einer farbkodierten Darstellung ein detaillierter Algorithmus entwickelt, der sich als Hauptergebnis der vorliegenden Arbeit als hoch reliabel erwies. In der vorliegenden Pilotstudie wurde darüber hinaus das Mamillarkörper-Volumen von 14 Patientinnen und Patienten mit einer Bipolaren Störung und 20 gesunden Kontrollpersonen anhand von hochaufgelösten T1-gewichteten MRT-Bildern bestimmt. Ein signifikanter Unterschied zwischen den beiden Gruppen konnte nicht nachgewiesen werden, ebenso kein Unterschied zwischen den Geschlechtern. Es konnte gezeigt werden, dass das Volumen der Mamillarkörper signifikant invers mit dem Alter der ProbandInnen korreliert. Des Weiteren wurde eine signifikante positive Korrelation mit dem Gesamthirnvolumen der ProbandInnen festgestellt. Krankheitsschwere und Episodenzahl hingegen hatten keinen Einfluss auf das Mamillarkörper-Volumen. Die Ergebnisse dieser Pilotstudie sollten anhand einer größeren Stichprobe überprüft werden.