Multi-channel MAC protocol is that schedules frames to be exchanged on different channels. To analyze the performance of multi-channel MAC protocol, an analytical model is proposed to compute the network throughput. Simulation results show that the proposed model is able to model the behaviors of multi-channel MAC protocol accurately. Furthermore, based on the analysis model, in this thesis we also proposes an adaptive contention window scheme to enhance the network throughput by tuning the initial contention window size. Results indicate that the proposed scheme can reduce the cost of collisions and increase the network throughput.

The initial research of this thesis involves the evaluation of different strategies for developing diverse chemistries of highly stable coatings for the automated 96-blade (thin-film) solid phase microextraction (SPME) system. Thin-film geometry increases the volume of extractive phase, and consequently improves the sensitivity of the analysis. Sol-gel technology was used for the preparation of octadecyl (C18)-silica gel thin-film coating. The evaluation of the C18-silica gel SPME extractive phase resulted in stable physical and chemical characteristics and long-term reusability with a high degree of reproducibility. Biocompatible polyacrylonitrile (PAN) polymer was used for the preparation of particle-based extractive phases in order to improve the biocompatible characteristics of SPME coatings for the extraction from biological samples. Three different immobilization strategies were evaluated for developing highly stable coatings for the automated 96-blade SPME system. The spraying was found to be the optimal method in terms of stability and reusability for long-term use. The optimized C18-PAN coating demonstrated improved biocompatibility, stability, and reusability for the extraction of benzodiazepines from human plasma in comparison with those of C18-silica gel coating. To improve the biocompatible properties of the C18-PAN SPME coating for long-term direct analysis from whole blood, different modification strategies were studied and evaluated. The modification of the coating with an extra layer of biocompatible polyacrylonitrile resulted in significant improvement in the blood compatibility in long-term use. ‘Extracted blood spot’ (EBS) sampling was introduced as a novel approach to overcome the limitations of dried blood spot sampling. EBS includes the application of a biocompatible SPME coating for spot sampling of blood or other biofluids. The compatibility of EBS sampling with different analytical methods was demonstrated. The utilization of EBS as a fast sampling and sample preparation method resulted in a significant reduction of matrix effects through efficient sample clean-up. Modified polystyrene-divinylbenzene (PS-DVB)-PAN and phenylboronic acid (PBA)-PAN 96-blade SPME coatings were developed and evaluated for the extraction of analytes in a wide range of polarity. These coatings demonstrated efficient extraction recovery for both polar and non-polar groups of compounds, and presented chemical and mechanical stabilities and reproducible extraction efficiencies for more than 100 usages in biological sample.

The initial research of this thesis involves the evaluation of different strategies for developing diverse chemistries of highly stable coatings for the automated 96-blade (thin-film) solid phase microextraction (SPME) system. Thin-film geometry increases the volume of extractive phase, and consequently improves the sensitivity of the analysis. Sol-gel technology was used for the preparation of octadecyl (C18)-silica gel thin-film coating. The evaluation of the C18-silica gel SPME extractive phase resulted in stable physical and chemical characteristics and long-term reusability with a high degree of reproducibility. Biocompatible polyacrylonitrile (PAN) polymer was used for the preparation of particle-based extractive phases in order to improve the biocompatible characteristics of SPME coatings for the extraction from biological samples. Three different immobilization strategies were evaluated for developing highly stable coatings for the automated 96-blade SPME system. The spraying was found to be the optimal method in terms of stability and reusability for long-term use. The optimized C18-PAN coating demonstrated improved biocompatibility, stability, and reusability for the extraction of benzodiazepines from human plasma in comparison with those of C18-silica gel coating. To improve the biocompatible properties of the C18-PAN SPME coating for long-term direct analysis from whole blood, different modification strategies were studied and evaluated. The modification of the coating with an extra layer of biocompatible polyacrylonitrile resulted in significant improvement in the blood compatibility in long-term use. ‘Extracted blood spot’ (EBS) sampling was introduced as a novel approach to overcome the limitations of dried blood spot sampling. EBS includes the application of a biocompatible SPME coating for spot sampling of blood or other biofluids. The compatibility of EBS sampling with different analytical methods was demonstrated. The utilization of EBS as a fast sampling and sample preparation method resulted in a significant reduction of matrix effects through efficient sample clean-up. Modified polystyrene-divinylbenzene (PS-DVB)-PAN and phenylboronic acid (PBA)-PAN 96-blade SPME coatings were developed and evaluated for the extraction of analytes in a wide range of polarity. These coatings demonstrated efficient extraction recovery for both polar and non-polar groups of compounds, and presented chemical and mechanical stabilities and reproducible extraction efficiencies for more than 100 usages in biological sample.

Les LPSNC représentent une localisation rare des lymphomes B diffus à grandes cellules (LBDGC), d’immunophénotype post-GC, dont la tumorigenèse reste mal connue.Notre objectif était de caractériser les altérations moléculaires des LPSNC à l’aide de techniques d’analyse haut débit.Notre projet a montré comme principaux résultats : 1/ la haute fréquence de mutations touchant des gènes impliqués dans la voie de signalisation BCR/TLR/NF-κB, en particulier MYD88, CD79B et TBL1XR1 ; 2/ des déséquilibres chromosomiques récurrents, en particulier la perte du 6q22 et du 6p (locus HLA) ; 3/ des mutations du promoteur de TERT et 4/ des transcrits de fusions ETV6-IGH.Plusieurs altérations semblent être des biomarqueurs pronostiques (i.e perte du 6q22 et délétions homozygotes de CDKN2A), prédictifs de réponse au traitement ou des cibles prometteuses pour des thérapies innovantes.En conclusion, il existe une grande similitude entre le profil moléculaire des LPSNC et celui des LBDGC extra-cérébraux avec néanmoins quelques spécificités. Les LPSNC peuvent résulter d’une tumorigenèse propre mais aussi de son microenvironnement singulier. / PCNSL represent a rare extranodal diffuse large B cell lymphoma (DLBCL) with a post-GC phenotype whose tumorigenesis is still poorly unknown.Our objective was to characterize the molecular genetic alterations of PCNSL using high throughput technologies.Results: We demonstrated 1/ a high incidence of somatic mutations in genes involved in the BCR/TLR/NF-κB pathway, especially MYD88, CD79B and TBL1XR1; 2/ recurrent chromosome imbalances such as 6q22 loss and 6q (HLA locus) homozygous deletions; 3/ TERT promoter mutations and 4/ gene fusions such as ETV6-IGH. Several alterations are associated with a prognostic impact (6q22 loss and CDKN2A homozygous deletions) or are promising targets for novel therapies.To conclude, PCNSL and extracerebral DLBCL share many similarities in terms of molecular genetic profile despite some specificities. PCNSL may result from a specific tumorigenesis but also from its peculiar microenvironment.

No description available.

L'utilisation d'organismes génétiques modèles a permis l'investigation à grande échelle de mécanismes cellulaires et moléculaires pour la biologie. La larve de poisson zèbre (Danio rerio) est un organisme vertébré modèle simple qui présente plusieurs avantages pour identifier les bases moléculaires et pharmacologiques du développement et du comportement à travers des cribles génétiques et chimiques respectivement. Plusieurs paradigmes expérimentaux reposent sur une caractérisation précise du phénotype comportemental associé avec un génotype ou l’application d’une drogue. Ce processus de phénotypage bénéficierait d'une compréhension globale des manœuvres possibles afin de caractériser précisément le comportement globale de larves observé au cours d'une expérience. L'analyse sur plusieurs minutes de la locomotion spontanée des larves de poisson zèbre en groupe fournit un cadre idéal pour atteindre ces objectifs.Si l'analyse manuelle du comportement animal est possible pour l'observation de manœuvres isolées et stéréotypées, elle n’est pas compatible avec une approche à grande échelle. A partir de cinq jours, la larve de poisson zèbre se meut sous forme de bouffées natatoires qui arrivent à haute fréquence et sont séparées par quelques secondes. La difficulté d'observation à haute fréquence et d'analyse de la locomotion en bouffée rend une analyse manuelle simple à partir de séquences vidéos du comportement impossible. Le développement récent de caméras rapides avec acquisition en mode continu, couplé aux avancées en informatique et en intelligence artificielle rend possible une analyse automatique du comportement. Les systèmes commerciaux actuels permettent des enregistrements sur des longues durées mais sans capturer la complexité et la diversité des mouvements réalisés. Nous avons donc créé ZebraZoom, notre système d'analyse haut débit permettant de suivre, de quantifier et de catégoriser le comportement spontané de chaque larve de poisson zèbre au sein d’un groupe.Nous avons monté un dispositif expérimental qui consiste à placer sept larves de poisson zèbre âgées d'entre cinq et sept jours dans huit boîtes de pétri. Les boîtes de pétri sont disposées sur une table lumineuse et une caméra rapide positionnée au-dessus enregistre le comportement spontané à 337 Hz pendant quatre minutes. Une fois la vidéo acquise, ZebraZoom localise automatiquement chacune des huit boîtes de pétri, puis suit tête et queue de chacun des animaux sur l'ensemble de la vidéo, grâce à des procédures de vision par ordinateur. ZebraZoom identifie automatiquement chaque bouffée natatoire. Le phénotypage du comportement a été réalisé grâce à deux méthodes complémentaires : l'extraction de paramètres globaux caractérisant la dynamique des mouvements et la catégorisation automatique des mouvements en différents manœuvres stéréotypées. Nous avons utilisé l’analyse des paramètres globaux afin de caractériser l'effet de drogues agissant sur les récepteurs de neurotransmetteurs et l’analyse d’un mutant aveugle. La catégorisation automatique des mouvements est réalisée grâce a des procédures d’apprentissage automatique (« Machine Learning »). Nous avons illustré l’utilité de cette catégorisation pour étudier les interactions entre larves à ces stades précoces. En conclusion, notre programme ZebraZoom permet de réaliser un phénotypage automatique et complet, et cette approche pourra être appliquée dans d'autres systèmes et contextes expérimentaux. / The use of simple genetic model organisms has allowed large-scale investigation of cellular and molecular mechanisms in biology. The zebrafish larva (Danio rerio) is a simple vertebrate model with several advantages for the identification of the molecular and pharmacological basis of development and behavior thanks to genetic and chemical screens. Several experimental paradigms rely on a precise behavioral characterization associated with a genotype or a drug application. This phenotyping process would benefit from a global comprehension of all possible zebrafish larvae maneuvers in order to precisely characterize the global behavior of larvae observed during an experiment. The analysis over multiple minutes of the spontaneous locomotion of zebrafish larvae in a group provides an ideal framework for achieving these goals.The manual analysis of animal behavior is possible for the observation of stereotyped and isolated maneuvers, but it is not compatible with large-scale approaches. After five days, the zebrafish larva moves in burst of movement occurring at high frequency and separated by a few seconds. The difficulty of observation of high-frequency maneuvers makes a manual analysis of videos impossible. The recent development of high-speed cameras, coupled with advances in computer science and artificial intelligence, make an automatic analysis of behavior possible. The available commercial solutions allow long acquisitions but without capturing all the complexity and diversity of the movements. We thus created ZebraZoom, our high-throughput analysis system which makes it possible to follow, quantify and categorize the spontaneous behavior of all zebrafish larva in a group.We built an experimental setup which consisted in placing seven 5- to 7-day old zebrafish larvae in eight petri dishes. The petri dishes were placed on a light table and a high-speed camera was placed above the setup and allowed to record the spontaneous behavior at 337 Hz during four minutes. Once the video was acquired, ZebraZoom localized automatically each of the eight petri dishes and followed the head and the tail of each of the animals on the entire video, thanks to computer vision methods. ZebraZoom then identifies automatically all burst of movement.The behavior phenotyping was performed thanks to two complementary methods: the extraction of global parameters characterizing movement dynamics and the automatic categorization of movements into stereotyped maneuvers. We used global parameters analysis to characterize the effect of drugs acting on neurotransmitters receptors and to analyze the behavior of a blind mutant. The automatic categorization of movements was carried out thanks to machine learning procedures. We showed the utility of this categorization method in studying interactions between larvae at early stages. In conclusion, our ZebraZoom program makes it possible to carry out an automatic and complete phenotyping, and this approach could be used in other systems and experimental contexts.

<p>The rapid analysis of complex samples using mass spectrometry (MS) provides valuable information in both point-of-care (e.g. drug testing) and laboratory-based applications, including the generation of spectral libraries for classification of biosamples, the identification of biomarkers through large-scale studies, as well as the synthesis and bioactivity assessments of large compound sets necessary for drug discovery. In all these cases, the inherent speed of MS is attractive, but rarely fully utilized due to the widespread use of sample purification techniques prior to analysis. Ambient ionization methodologies can help circumvent this drawback by facilitating high-throughput qualitative and quantitative analysis directly from the complex samples without any need for work-up. For instance, the use of swabs or paper substrates allows for rapid identification, quantification, and confirmation, of drugs of abuse from biofluids or surfaces of forensic interest in a matter of minutes, as described in the first two chapters of this dissertation. Faster analysis can be achieved using an automated desorption electrospray ionization (DESI) platform which allows for the rapid and direct screening of complex-sample microarrays with throughputs better than 1 sample per second, giving access to rich spectral information from tens of thousands of samples per day. The development of the bioanalytical capabilities of this platform, particularly within the context of drug discovery (e.g. bioactivity assays, biosample analysis), is described across most other chapters of this dissertation. The use of DESI, a contactless ambient ionization method developed in our laboratory and whose 20 years of history are overviewed in the introduction of this document, provides an additional advantage as the secondary microdroplets generated through the DESI process act as reaction vessels that can accelerate organic reactions by up to six orders of magnitude, facilitating on-the-fly synthesis of new compounds from arrays of starting materials. Unique implications of this microdroplet chemistry in the prebiotic synthesis of peptides and spontaneous redox chemistry at air-solution interfaces, together with its practical applications to the synthesis of new drug molecules, are also overviewed. The success obtained with the first automated DESI-MS system, developed within the DARPA Make It program, led to increased interest in a new-generation platform which was designed over the past year, as overviewed in the last section of this dissertation, and which is currently being installed for validation prior to the transfer of the technology to NCATS, where we anticipate it will make a significant impact through the consolidation and acceleration of the early drug discovery workflow.</p>

科学研究費補助金 研究種目:基盤研究(B)(2) 課題番号:07455160 研究代表者:小川 明 研究期間:1995-1996年度