Bien que les troubles anxio-dépressifs représentent une des principales causes d’invalidité et un des plus sérieux problèmes de santé dans le monde, les mécanismes neurobiologiques à l’origine de ces affections demeurent méconnus. Les processus mis en jeu semblent multiples et complexes : passant par des déséquilibres au niveau des neurotransmetteurs jusqu’à des modifications de la plasticité neurale et du remodelage cellulaire. Les neurotrophines étant considérées comme les principaux régulateurs de la plasticité, l’hypothèse d’un lien causal entre le niveau de neurotrophine, principalement de l’une d’entre elles, le Brain-Derived Neurotrophic Factor (BDNF) et l’apparition de troubles anxio-dépressifs a ainsi été proposée. Notre travail a donc eu pour objectif l’étude de l’implication du BDNF dans l’étiopathogenèse et le traitement des troubles anxio- dépressifs à travers l’utilisation de modèles murins. Etant donné que plusieurs études cliniques et précliniques ont montré une implication du BDNF dans plusieurs traits psychologiques et comportementaux, nous avons cherché à déterminer si des différences dans le gène BDNF pouvaient être à l’origine de la grande hétérogénéité comportementale des différentes souches de souris. Nous rapportons dans cette étude l’existence d’un polymorphisme sur un seul nucléotide (SNP) à l’origine d’un changement d’acide aminé (une leucine est remplacé par une méthionine) en position 32 dans la séquence du prodomaine du BDNF. Nous démontrons ensuite que, bien que ce SNP ne modifie par l’expression basale de BDNF dans le cerveau, ce polymorphisme est associé au phénotype « anxieux » des souris. Par contre, il n’est pas impliqué dans le comportement alimentaire, le toilettage, l’activité, l’apprentissage et la mémoire. / Although anxio-depressive disorders are a major cause of disability with important health consequences, the underlying neurobiological mechanisms remain largely unknown. Neurotransmitter imbalances can change numerous intracellular signaling pathways that ultimately result in lasting modifications in neural plasticity and cellular remodeling. Since neurotrophins, and particularly brain-derived neurotrophic factor (BDNF), are considered main regulators of neural plasticity, changes in the expression of these genes are an attractive mechanism by which normally differentiated brain cells may transform into a pathological anxio-depressive phenotype. A first study seven strains of mice with large behavioral differences were used to investigate whether differences in the expression and sequence BNDF may be associated with anxiety and depressive traits. A change of a single nucleotide in position 32 of prodomain sequence of BNDF, which resulted in a leucine being replaced by methionine, was associated with mice exhibiting the anxious phenotype. Mice carrying the Met allele had greater propensity to neophobic reactions and behaviors related to anxiety. However, this polymorphism did not alter the basal expression of the gene and other behavioral activities including appetite, thirst, grooming, learning and memory. Furthemore, when chronic stress slightly unpredictable (UCMS) was used in seven mouse lines, no association was observed between Leu 32 Met and depression-like effectors due to antidepressant treatments. When heterozygous (+/-) BNDF mice were used in the UCMS model, no changes were noted in physical observations (i.e, hair coat, weight), behavioral responses (to mimic anxiety, aggressiveness and resignation) and in the stress hormones; by contrast, some effects to the anti-depressants were different from the ones seen in homozygous (+/+) mice. In conclusion, BDNF polymorphisms can contribute to the various behavioral profiles exhibited by different strains of mice in test of anxiety. However, it does not appear to be involved in the etiopathogenesis of depression.

La dépression est considérée comme un facteur de risque capable de prédire l‟apparition de maladies cardiovasculaires. L'objectif de ce travail est de développer un modèle animal capable de reproduire les altérations vasculaires et la résistance aux traitements observés chez les patients dépressifs qui présentent des risques cardiovasculaires. La formation d'athérosclérose et la fonction endothéliale sont évaluées chez des souris exposées au stress chronique imprédictible (UCMS) qui constitue un modèle valide de dépression et les effets comportementaux d‟un traitement antidépresseur sont évalués chez des souris UCMS recevant un régime hyper lipidique. Nos résultats montrent que l‟UCMS induit un état de type dépressif et un dysfonctionnement endothélial qui n‟est pas suffisant pour induire de l‟athérosclérose. Le régime hyper lipidique abolit les effets antidépresseurs de la fluoxétine. Ces résultats suggèrent que ce modèle reproduit les altérations physiologiques mais non morphologique aussi bien que la résistance aux traitements des patients dépressifs présentant des facteurs de risques cardiovasculaires. / Epidemiologic studies have demonstrated that depressive symptoms can predict cardiovascular disease in healthy patients. The purpose of this study was to develop an animal model able to reproduce the vascular alterations and the treatment resistance observed in depressed subjects who develop vascular disease. Atherosclerotic plaque formation and endothelial dysfunction were assessed in mice exposed to the Unpredictable Chronic Mild Stress (UCMS) that constitute a reliable animal model of depression and the reversal effect of antidepressant was assessed in UCMS mice fed a high fat diet. Our results show that high fat diet regimen prevented the reversal effect of chronic fluoxetine treatment on UCMS-induced depressive-like behaviour. Moreover, UCMS-induced endothelial dysfunction was not associated with atherosclerotic plaque formation. These findings suggest that this model can reproduce the physiological but not the morphological vascular alterations observed in depressed patients who develop vascular disease as well as the reported treatment resistance in depressed patients also suffering from cardiovascular risk factor.

Bien que les troubles dépressifs soient l'un des plus graves problèmes de santé dans le monde, les mécanismes neurobiologiques à la base de la pathophysiologie et du traitement de la dépression demeurent méconnus. Dans ce travail de thèse, nous avons directement testé l'hypothèse d'une diminution de la neurogénèse hippocampique à l'origine de la dépression à travers l'utilisation d'un modèle murin, le Stress Chronique Léger Imprédictible (UCMS), et de souris ayant préalablement subi trois radiations focalisées sur l'ippocampe afin de réprimer toute prolifération des cellules souches neurales. Tout d'abord, nos résultats n'identifient pas la perturbation de la neurogénèse hippocampique est nécessaire aux antidépresseurs monoaminergiques (imipramine et fluoxétine), mais aussi qu'un effet "thérapeutique" peut être produit, même en l'absence de neurogénèse hippocampique, en ciblant directement les circuits du stress dont l'axe HPA (antagonistes CRF1 ou V1b). Enfin, dans le but de déterminer le rôle exact de ces nouveaux neurones, une dernière étude a été réalisée dans laquelle la fluoxétine fut incapable de rétablir chez la souris irradiée le contrôle de l'hippocampe sur l'axe HPA. Ce dernier résultat fournit la première démonstration d'une contribution des neurones produits chez l'adulte dans la régulation de l'axe HPA. Ainsi, l'accroissement du nombre de nouveaux neurones hippocampiques pourraient être un levier par lequel les antidépresseurs rétablissent le contrôle central sur les circuits de stress et peut-être initient la rémission clinique. / Although depressive disorders represent one of the most serious health problems worldwide, the neurobiological mechanismes underlying the pathophysiology and the treatment of depression remains poorly known. In this work, we directly tested the hypothesis of a diminution of hippocampal neurogenesis as a cause for depression by unsing a mouse model, the Unpredictble Chronic Mild Stress (UCMS) and an hippocampal X-irradiation procedure in order to abolish neural stem cell proliferation. Firstly, our results did not identify the disruption of hippocampal neurogenesis as a causal or a risk factor for depression. However, we demonstrated that hippocampal neurogenesis is required for the effects of monoaminergic antidepressant (imipramine and fluoxetine), but that reversals can arise, even without the ability to increase the number of new neurons, by targeting stress-related circuit and HPA axis with CRF1 or V1b receptor antagonists. Moreover, in order to determine the functional role of new hippocampal neurons in antidepressant effects, we performed a last study in which fluoxetine was unable in irradiated mice to improve the hippocampal control on HPA axis which is disrupted in UCMS and depression. Finally, the last result provides the first demonstration of the involvement of new neurons in the hippocampal regulation of HPA axis. Enhancing hippocampal neurogenesis might thus be a mechanism by which antidepressant drugs restore central control on the stress circuits, and perhaps initiate recovery.

This thesis reports the results of investigations carried out into the composition of the saturate and aromatic unresolved complex mixtures (UCMs) in crude oils. It is divided into two sections. Section A reports on studies of the saturate UCM and Section B reports on studies of the aromatic UCM. UCMs are mixtures of very large numbers of compounds of low individual abundances, hence structural information on individual components is difficult or impossible to obtain using conventional GC or GC-MS techniques. The investigations reported in this thesis used a combination of GC-MS techniques (Section A) and oxidations of UCMs followed by GC-MS characterisation of the oxidation products (Section B) to develop a more detailed picture of the structures of components of the saturate and aromatic UCMs. UCMs are present in all crude oils, and may account for the vast majority of the material present in heavily weathered or biodegraded oils. An understanding of the types of compounds present may have a bearing on the refining processes an oil is subjected to, as well as assessing its potential environmental and toxicological effects.Single branched C(subscript)18 isomers were prepared to establish the chromatographic behaviour and mass spectral fragmentation patterns of open chain compounds with ethyl-, propyl-, butyl- and pentyl- substituents. All open chain structural isomers with a single n-alkyl branch larger than methyl in the range C(subscript)10 to C(subscript)20 were identified at each carbon number in a series of crude oils of varying ages, source types and depositional environments. Also, C(subscript)21 to C(subscript)25 structural isomers containing an ethyl branch were identified in all of these samples. This represents a total of 163 compounds. These monoalkylalkanes comprise approximately 3 % of the alkanes in these oils, with the n-alkanes (35-60 %) and ++ / methylalkanes (10 %) being the most abundant compound classes present. Isoprenoids, alkylcyclohexanes and other branched and/or cyclic alkanes make up the remainder of the material.Rock samples from a sedimentary sequence of Late Cretaceous age were analysed for ethylalkanes using GC-MS techniques. In the less mature samples, 3- and 5-ethylalkanes were in higher abundance relative to the other isomers at odd carbon numbers from C(subscript)17 to C(subscript)23. In the more mature samples, this odd preference was no longer apparent. Several other low maturity sediment samples were analysed and found to have a similar ethylalkane distribution to the shallow sample from the sedimentary sequence. A mature crude oil which was also analysed exhibited a distribution similar to the deeper sample from the sedimentary sequence. Tetralin pyrolysis of a low maturity lignite sample yielded only the 3- and 5-substituted ethylalkanes, providing supporting evidence that the initial odd preference is the result of defunctionalisation of specific natural product precursors containing a 3- or 5-ethylalkyl structural moiety. With increasing maturity this preference is diluted by input of ethylalkanes without preference. A mechanism involving acid-catalysed rearrangement of n-alkenes to form monoalkylalkanes is proposed to account for the loss of preference in ethylalkane relative abundances.Investigations into the composition of aromatic unresolved complex mixtures were conducted by oxidising the total aromatic fraction of a moderately biodegraded crude oil (biodegradation level 4) using potassium permanganate. This reagent cleaves the alkyl substituents attached to aromatic rings between the alpha and beta carbons and oxidises the alpha carbon to a carboxylate group. A biodegraded crude oil was chosen because the majority of the resolved components have been removed by biodegradation, ++ / leaving a complex mixture of compounds almost completely unresolved by gas chromatography. The oxidation product was separated into dichloromethane-soluble monocarboxylic acids (both aliphatic and aromatic) and water-soluble polycarboxylic acids (aromatic only). GC-MS analysis of these oxidation products gave the proportions of monosubstituted:disubstituted:trisubstituted:tetrasubstituted monoaromatic rings as 29:59:12:0.1, of which from one to three substituents were carboxylic acid groups with the remainder of the substituents being unoxidised methyl groups. Of the disubstituted monoaromatic oxidation products, 53 % were dicarboxylic acids with the most sterically hindered 1,2-substitution pattern. This observation was interpreted as evidence for the presence of significant amounts of naphthenoaromatic systems such as tetralins and indanes in the crude oil aromatic fraction. Analysis of the permanganate oxidation products also enabled a quantitative measure of the proportion of methyl substituents to be made. It was found that methyl groups accounted for a significant proportion of the alkyl substituents attached to aromatic systems. Of the disubstituted monoaromatic oxidation products, 59 % had a methyl group as one of the substituents, while of trisubstituted monoaromatic systems, 41% had one methyl and 37 % had two methyls. Compounds containing a biphenyl carbon skeleton comprised 3 % of the aromatic oxidation products, with isomers containing from one to four substituents of which one was a carboxylic acid group and the remainder were unoxidised methyls. This indicates that biphenyls containing more than one alkyl (>C(subscript)1) substituent were not present. Of the monosubstituted biphenylcarboxylic acids, the ratio of ortho:meta:para substituted isomers was 0:65:35, which correlates well with literature reports of the relative abundances of methylbiphenyl ++ / isomers, and suggests that the overall distribution of all monosubstituted biphenyls has not been significantly affected by biodegradation to level 4.The monoaromatic, diaromatic and triaromatic fractions of the same biodegraded crude oil (level 4) were separately treated with ruthenium tetroxide, which cleaves aromatic rings so that the ring carbon bearing the substituent is oxidised to become the carbonyl carbon of a carboxylic acid. These oxidation products represent the alkyl moieties that were attached to aromatic rings in the initial crude oil aromatic fractions. Identification of these alkyl side chains provides an insight into the nature of the components of the aromatic crude oil UCM. The oxidation products were separated into dichloromethane-soluble monocarboxylic acids, which were subsequently reduced to monodeuterated hydrocarbons for characterisation using gas chromatography-mass spectrometry (GC-MS) techniques, and water-soluble dicarboxylic acids which were analysed as dimethyl esters. n-Alkanes, methylalkanes, alkylalkanes, alkylcyclohexands, methylalkylcyclohexanes, isoprenoids and bicyclic alkanes were identified in the monodeuterated hydrocarbon samples derived from all three aromatic fractions. Most of these compounds had carbon skeletons strikingly similar to those observed in the saturate fractions of unbiodegraded crude oils, with the only differences being the addition of a carbon from the aromatic ring, and the presence of a deuterium atom attached to that carbon. Because the electron-withdrawing nature of carboxylic acid groups prevents further aromatic ring oxidation, numerous aromatic monocarboxylic acids were also identified in the acidic products of the oxidation of the crude oil diaromatic and triaromatic fractions. These included C(subscript)1 to C(subscript)3 alkyl-substituted benzoic acids derived from compounds containing a biphenyl ++ / or phenylnaphthalene structural moiety, as well as omega-phenylalkanoic acids with chain lengths up to C(subscript)11, derived from compounds in which two aromatic systems are connected by an alkyl chain. The main components of the dicarboxylic acid oxidation products of all three aromatic fractions were alpha, omega-dicarboxylic acids and alkylcyclopentane-dicarboxylic acids and alkylcyclohexane-dicarboxylic acids, with phthalic acids also present in the oxidation products of the diaromatic and triaromatic fractions. The observation that 1,5-pentanedicarboxylic acids and 1,6-hexanedicarboxylic acids were the only alpha, omega-dicarboxylic acids in the oxidation products of the crude oil monoaromatic fraction, and were present in high abundance relative to other alpha, omega-dicarboxylic acids in the oxidation products of the diaromatic and triaromatic fractions indicated that substituted indanes and/or tetralins were quantitatively important constituents of the overall crude oil aromatic fraction. This finding is supported by the results of the analysis of the mass spectra of the crude oil aromatic fractions.These studies of aromatic UCMs have provided new insights into the origins of the aromatic components of petroleum. The presence of a pronounced odd-over-even predominance in the C(subscript)25, C(subscript)27, and C(subscript)29 monodeuterated n-alkanes (CPI = 1.07), which corresponds to the odd-over-even predominance observed in the n-alkane components of unbiodegraded crude oils from the same basin, suggests that the n-alkyl side chains and the n-alkanes have a common source. Evidence is presented to support the hypothesis that the n-alkylaromatics are formed in part by geosynthetic processes involving alkylation of aromatic systems by electrophilic species such as carbocations and acylium ions formed from carboxylic acids. This hypothesis is then extended to ++ / explain the formation of other groups of compounds, including aromatic systems with isoprenoidal-, methylalkyl- and monoalkyl-branched side chains. Because isoprenoids, methylalkanes and alkylalkanes are well-known components of petroleum, these results suggest that these alkylaromatic components of petroleum may share a common source with the corresponding alkane components. It is suggested that aromatic unresolved complex mixtures arise due to the very large number of structurally related compounds present, which are formed by geosynthetic processes such as alkylation of aromatic rings.

Le projet de cette thèse s'est attaché à caractériser le rôle de l'IL-1 beta et les récepteurs P2X7 dans la dépression. Les résultats suggèrent que chez les souris stressés et les perturbation comportementaux, l'activation microgliales et endocriniennes sont reversées par l'antagoniste des P2X7Rs. Ces résultats mettent en évidence que l'antagoniste des récepteurs P2X7 a des effets comportementaux et neuroendocriniens. / Research work of this thesis was aimed to characterize role of IL-1 beta and P2X7 receptors in depressive illness. Results suggest that i stressed mice the behavioral and neurobiochemical changes are reversed by use of P2X7R antagonist. It is an evidence of antidepressant of these compounds.

Formal specification of software systems has been very promising. Critics against the end results of formal methods, that is, producing quality software products, is certainly rare. Instead, reasons have been formulated to justify why the adoption of the technique in industry remains limited. Some of the reasons are: • Steap learning curve; formal techniques are said to be hard to use. • Lack of a step-by-step construction mechanism and poor guidance. • Difficulty to integrate the technique into the existing software processes. Z is, arguably, one of the successful formal specification techniques that was extended to Object-Z to accommodate object-orientation. The Z notation is based on first-order logic and a strongly typed fragment of Zermelo-Fraenkel set theory. Some attempts have been made to couple Z with semi-formal notations such as UML. However, the case of coupling Object-Z (and also Z) and the Use Case Maps (UCMs) notation is still to be explored. A Use Case Map (UCM) is a scenario-based visual notation facilitating the requirements definition of complex systems. A UCM may be generated either from a set of informal requirements, or from use cases normally expressed in natural language. UCMs have the potential to bring more clarity into the functional description of a system. It may furthermore eliminate possible errors in the user requirements. But UCMs are not suitable to reason formally about system behaviour. In this dissertation, we aim to demonstrate that a UCM can be transformed into Z and Object-Z, by providing a transformation framework. Through a case study, the impact of using UCM as an intermediate step in the process of producing a Z and Object-Z specification is explored. The aim is to improve on the constructivity of Z and Object-Z, provide more guidance, and address the issue of integrating them into the existing Software Requirements engineering process. / Computer Science / M. Sc. (Computer Science)

Formal specification of software systems has been very promising. Critics against the end results of formal methods, that is, producing quality software products, is certainly rare. Instead, reasons have been formulated to justify why the adoption of the technique in industry remains limited. Some of the reasons are: • Steap learning curve; formal techniques are said to be hard to use. • Lack of a step-by-step construction mechanism and poor guidance. • Difficulty to integrate the technique into the existing software processes. Z is, arguably, one of the successful formal specification techniques that was extended to Object-Z to accommodate object-orientation. The Z notation is based on first-order logic and a strongly typed fragment of Zermelo-Fraenkel set theory. Some attempts have been made to couple Z with semi-formal notations such as UML. However, the case of coupling Object-Z (and also Z) and the Use Case Maps (UCMs) notation is still to be explored. A Use Case Map (UCM) is a scenario-based visual notation facilitating the requirements definition of complex systems. A UCM may be generated either from a set of informal requirements, or from use cases normally expressed in natural language. UCMs have the potential to bring more clarity into the functional description of a system. It may furthermore eliminate possible errors in the user requirements. But UCMs are not suitable to reason formally about system behaviour. In this dissertation, we aim to demonstrate that a UCM can be transformed into Z and Object-Z, by providing a transformation framework. Through a case study, the impact of using UCM as an intermediate step in the process of producing a Z and Object-Z specification is explored. The aim is to improve on the constructivity of Z and Object-Z, provide more guidance, and address the issue of integrating them into the existing Software Requirements engineering process. / Computer Science / M. Sc. (Computer Science) / D. Phil. (Computer Science)

The growing need for computer software in different sectors of activity, (health, agriculture, industries, education, aeronautic, science and telecommunication) together with the increasing reliance of the society as a whole on information technology, is placing a heavy and fast growing demand on complex and high quality software systems. In this regard, the anticipation has been on non-functional requirements (NFRs) engineering and formal methods. Despite their common objective, these techniques have in most cases evolved separately. NFRs engineering proceeds firstly, by deriving measures to evaluate the quality of the constructed software (product-oriented approach), and secondarily by improving the engineering process (process-oriented approach). With the ability to combine the analysis of both functional and non-functional requirements, Goal-Oriented Requirements Engineering (GORE) approaches have become de facto leading requirements engineering methods. They propose through refinement/operationalisation, means to satisfy NFRs encoded in softgoals at an early phase of software development. On the other side, formal methods have kept, so far, their promise to eliminate errors in software artefacts to produce high quality software products and are therefore particularly solicited for safety and mission critical systems for which a single error may cause great loss including human life. This thesis introduces the concept of Complementary Non-functional action (CNF-action) to extend the analysis and development of NFRs beyond the traditional goals/softgoals analysis, based on refinement/operationalisation, and to propagate the influence of NFRs to other software construction phases. Mechanisms are also developed to integrate the formal technique Z/Object-Z into the standardised User Requirements Notation (URN) to formalise GRL models describing functional and non-functional requirements, to propagate CNF-actions of the formalised NFRs to UCMs maps, to facilitate URN construction process and the quality of URN models. / School of Computing / D. Phil (Computer Science)