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Structural characterization of cyclodextrins: from inclusion complexes to Metal-Organic Frameworks (MOFs)
No full textCyclodextrins (CD) are cyclic oligosaccharides composed of six to more than sixty glucose units. α-CD, β-CD and γ-CD are well known CD consisting of 6, 7 and 8 glycopyranose units, respectively, that are torus-like rings built up from glycopyranose units. The secondary hydroxyl groups are situated on one of the two edges of the ring, whereas all the primary ones are placed on the other edge. The ring is a conical cylinder, which is frequently characterized as a doughnut or wreath shaped truncated cone. The cavity is lined with hydrogen atoms and glycosidic oxygen bridges, respectively. The primary and secondary hydroxyls on the outside of the cyclodextrins make cyclodextrins water-soluble. The cavity of the cyclodextrin consists of a ring of C-H groups, a ring of glycosidic oxygen atoms and again a ring of C-H groups. This renders the interior of the cyclodextrin rings less polar. As a consequence, the hydrophilic sites which are outside of the torus enable CD to be soluble in water, whereas the apolar cavity site which provides a hydrophobic matrix, enables CD to form inclusion complex with a variety of hydrophobic guest molecules. In addition, CD contains repeating units of ‒OCCO‒ binding motif on both their primary and secondary faces. This makes CD able to form extended structures with metal cations of Group IA and IIA (MOFs). The main goal of this thesis was to design, prepare and characterize new crystal systems based on cyclodextrins properties in combination with: 1. Para aminobenzoic acid (pABA) as a drug model to study the effect of complexation phenomena on the solubility of drugs. Their structure and mode of interaction were characterized by combination a theoretical and experimental approaches. 2. Potassium hydroxide to prepare cyclodextrin Metal-Organic Frameworks (CD-MOFs) formed by coordinating the cyclodextrins to potassium cation. Consequently, taking the advantages of this interaction between cyclodextrin and alkali metal cation, formation of inclusion complexes as CD-MOFs drug carrier was favored. 3. Aegelinol, a natural product, for analytical purposes to determine the absolute configuration of this compound by formation of an inclusion complex with a host of known chirality (cyclodextrins consists of several optically active D-glucose units). This should allow direct determination of the absolute configuration of the guest (aegelinol).(DOCSC02) -- FUNDP, 201
DISCOVERY OF NOVEL INHIBITORS OF THE MYCOBACTERIAL CELL WALL
No full textTuberculosis remains a major threat in the world; in 2012, 8.6 million new TB cases were found. After the human immunodeficiency virus (HIV), TB has been considered as one of the most infectious diseases in history and the second leading cause of death. Effective drugs treatments are known and have been used since 1960. New TB drugs have been tested in clinical trials. However, the appearance of multidrug resistant strains has urged the research for finding new therapeutic agents to cure tuberculosis. Among the different enzymes involved in the formation of the mycobacterial cell wall, UDP-Galactopyranose mutase (UGM) was identified as a new target. Indeed, this enzyme allows a peculiar reaction: the contraction of the cycle of UDP-Galp into UDP-Galf. This thesis was based on the identification of novel potential inhibitors of UGM in order to understand the mechanism of this enzyme. The enzymatic studies were performed on two different categories of molecules: UDP-F4-Galactose and natural products. In the first part of this project, we synthesized polyfluorinated sugars, UDP-F4-Galactose, as analogues of the natural substrate UDP-Galactofuranose. Thus, four fluorine atoms were introduced at 2 and 3 positions of the galactose. Then, biochemical assays of these molecules were carried out on UGM. The inhibition study allowed us to determine the binding affinity present between the UDP-F4-Galactose and the enzyme. The second part reported the screening of a small library of natural compounds which lead to identify new potential inhibitors of UGM. Biochemical assays and molecular modeling studies have been performed on these molecules to better understand the interactions between these compounds and UGM within the active site.(DOCSC02) -- FUNDP, 201
Effects of immunostimulants on the immune response and resistance of striped catfish (Pangasianodon hypophtalmus) to bacterial disease : in vitro and in vivo approaches.
No full textThe striped catfish (Pangasianodon hypophthalmus) farming system in the Mekong Delta of Viet Nam has been vigorously developed in recent years. It has resulted from expansion of farming areas, application of new farming techniques and an increase of intensification level. As in other developing striped catfish culture venture, health problems including disease outbreaks have been encountered. The use of chemicals and antibiotics in striped catfish farming has increased for prevention and treatment of diseases. These compounds have attracted criticism because of a potential hazard for fish health, environment risk and human consumers. The present study aimed to evaluate the efficiency of different immunostimulating compounds in striped catfish farming in order to reduce the use and impact of antibiotics and chemicals by alternative method of immunostimulation. A combination of in vitro and in vivo approaches was used to investigate the effects of Lipopolysaccharide (LPS) on immune responses of striped catfish. Some potential results of this research were highlighted. The innate immune system of striped catfish was significantly stimulated by LPS injection or feeding through the increase of respiratory burst, lysozyme and complement activities. Total of immunoglobulins was also enhanced in LPS treatment. A challenge test with a common bacterial pathogen (Edwardsiella ictaluri) for striped catfish was performed and documented that LPS could significantly reduce the cumulative mortality of fish, especially in low dose such as 3 mg LPS/kg fish for injection and 0.01% of LPS for oral. Proteomic analysis performed in both approaches suggested that LPS could stimulate the over-expression of several immune proteins such as complement component, lysozyme precursor, transferrin, immunoglobulin,… In addition, the results from in vitro also showed that the response of striped catfish to LPS involved an increase of many protein expression related in cytoskeleton, stress response, cell signaling, carbohydrate metabolic process as well as muscle contraction. All these protein responses result in an increase of the ability of striped catfish peripheral blood mononuclear cells (PBMC) to produce and secrete pro-inflammatory mediator, which is fundamental to fight against a pathogen invasion. Comparing the efficiency of different immunostimulants on immune responses and bacterial resistance of striped catfish was also investigated. The results suggested that all tested immunnostimulants (β-glucan, bovine lactoferrin, chitosan, levamisole and vitamin C) could significantly enhance the immune response in striped catfish and protect fish from bacteria damage. Among them levamisole at the dose 5 mg/kg fish performed as the best immunostimulant. From above results, levamisole and LPS were selected as immunostimulant in a comparative experiment aiming to evaluate whether these compounds could efficiently replace an antibiotic treatment in infected striped catfish by E. ictaluri. Both LPS and levamisole stimulated the immune system of striped catfish and reduce the cumulative mortality after challenge with bacteria. The fish mortality in treatments LPS and levamisole without anitibiotics did not significantly differ with the one of control (without immunostimulants) treated with antibiotics. These results are good evidences to support that LPS and levamisole can replace antibiotic treatment to protect striped catfish against Edwardsiella ictaluri. However, validation in field trials needs to be performed before advocating the use of LPS and levamisole in intensive striped catfish culture practices. Overall, the use of immunostimulants in striped catfish aquaculture appears as an excellent method to enhance the immune system and increase the bacterial resistance of this fish species, supporting the replacement of antibiotics by alternative method such as the immunomodulation.(DOCSC03) -- FUNDP, 201
On the components of adaptive immune response involved in the control of a primary and secondary infection by Brucella melitensis
No full textBrucellosis is a bacterial zoonose caused by organisms belonging to the genus Brucella. These bacteria are facultative intracellular pathogens that cause abortion in domestic (cattle, goats, sheeps, etc.) and wild (deers, bisons, etc.) animals and a febrile chronic illness in humans. The disease exists worldwide and continues to have a great health significance and economic importance in developing countries. Despite past and current efforts to eradicate brucellosis by vaccination and culling within cattle and herds, as many as 500 000 new human cases are reported annually worldwide. Vaccines against brucellosis were initially developed on an empirical basis. The current studies are moving towards a more rational design but are hindered by an incomplete knowledge of the in vivo life style of Brucella and the immune mechanisms involved in the establishment of a protective memory. Despite progresses, several fields of host adaptive immunity remain highly controversial such as the implication of B cells, CD4+ and CD8+ T cells. While it is commonly accepted that Brucella infection induces a Th1 immune response characterized by the production of IFN-γ that activates bactericidal mechanisms of macrophages, little has been described with regards to a potential implication of the Th2 response or the recently described Th17 response.
Objectives of this thesis were therefore to determinate the implication of lymphocyte subsets and signaling pathways after primary infection with Brucella melitensis and characterize their roles in the development of a protective secondary immune response in the murine experimental model.
In the first part of this study we clearly confirm the central role of MHC-II-dependent antigen presentation to CD4+ T cells and the IFN-γ-mediated Th1 response in the control of B. melitensis primary infection. We also report that the absence of B cells, MHC-I-dependent antigen presentation, Th2 and Th17 responses appears to have no important positive or negative impact on the course of infection.
In the second part of this work, we show that Brucella is able to persist several weeks in the blood of infected mice. Surprisingly, we found that bacteria are initially localized extracellularly and then infect erythrocytes where they are already detectable after 24h.
Finally, the last part demonstrates that humoral immunity and CD4+ Th1 cells are both necessary and complementary for a sterilizing immune response upon a secondary infection with B. melitensis. Circulating specific antibodies and IFN-γ production by CD4+ T cells activated at the site of infection after the re-call infection appear as key immunological markers of protection in the murine experimental model of Brucella infection.
In conclusion, this work improves our understanding of the nature of murine immune response developed following B. melitensis infection and tries to provide correlates of protection that could help to define rational strategies for designing new vaccines against brucellosis. This study also reveals for the first time that erythrocytes constitute an unexpected niche for Brucella, and maybe a currently undescribed way of transmission by blood-sucking arthropods.La brucellose est une zoonose bactérienne causée par des organismes appartenant au genre Brucella. Ces bactéries sont des pathogènes intracellulaires facultatifs qui causent l’avortement tant chez les animaux domestiques (bovins, chèvres, moutons, etc.) que sauvages (cerfs, bisons, etc.) et une maladie chronique chez l’homme. La brucellose est présente dans le monde entier et constitue un problème majeur de santé publique qui affecte également l’économie dans les pays en voie de développement. Malgré les efforts passés et présents visant à éradiquer la brucellose, notamment par la vaccination et l’abattage systématique des troupeaux infectés, plus de 500 000 nouveaux cas humains sont signalés chaque année dans le monde. À l’origine, les vaccins contre la brucellose ont été développés empiriquement. Les études vaccinales actuelles s’orientent vers une conception plus rationnelle, mais sont freinées par une méconnaissance du cycle infectieux de Brucella in vivo et des mécanismes immunitaires impliqués dans l’établissement d’une mémoire immunitaire protectrice. Malgré de récents progrès, plusieurs domaines de la réponse adaptative développée en modèle murin suite à l’infection par Brucella sont encore fort controversés, comme l’importance de l’implication des lymphocytes B, T CD4+ et T CD8+. Bien qu’il soit communément admis que l’infection par Brucella induit une réponse immunitaire de type Th1, caractérisée par la production d’IFN-γ qui active les mécanismes bactéricides des macrophages, peu de choses ont été décrites concernant une implication potentielle des réponses Th2 ou Th17.
En conséquence, les objectifs de cette thèse étaient de déterminer l’implication des différentes populations de lymphocytes et des voies de signalisation induites après infection par Brucella melitensis en modèle expérimental murin et de caractériser leurs rôles dans le développement d’une réponse immunitaire protectrice lors d’une ré-infection.
Dans la première partie de ce travail, nous avons clairement confirmé le rôle central de la voie de présentation des antigènes dépendante du MHC-II aux lymphocytes T CD4+ ainsi que la nécessité de la production d’IFN-γ par les lymphocytes Th1 dans le contrôle d’une infection primaire par B. melitensis. Nous avons également démontré que l’absence de lymphocytes B, de la voie de présentation dépendante du MHC-I ou des réponses Th2 et Th17 n’a pas d’impact majeur sur le déroulement de l’infection.
Dans la seconde partie de ce travail, nous avons montré que Brucella est capable de persister plusieurs semaines dans le sang de souris infectées. De manière surprenante, nous avons constaté que, dans un premier temps, les bactéries étaient libres dans le sang et qu’elles infectaient ensuite les globules rouges où elles sont déjà détectables après 24h.
Enfin, la dernière partie de ce travail démontre que les réponses humorale et cellulaire sont toutes deux complémentaires et nécessaires à l’établissement d’une réponse immune stérilisante lors d’une ré-infection par B. melitensis. Les anticorps circulants et la production d’IFN-γ par les lymphocytes T CD4+ activés sur le site d’infection lors d’une réponse secondaire apparaissent comme des effecteurs clés de la protection en modèle murin.
En conclusion, ce travail améliore notre compréhension de la réponse immunitaire induite par B. melitensis en modèle murin. Il essaye également de proposer des marqueurs immunologiques de protection qui pourraient aider à définir des stratégies plus rationnelles pour la conception de nouveaux vaccins contre la brucellose. Enfin, cette étude révèle pour la première fois que les globules rouges constituent une niche d’infection inattendue qui pourrait assurer la transmission de la brucellose par des insectes suceurs de sang.(DOCSC03) -- FUNDP, 201
Développement et validation d’une nouvelle méthode d’identification par spectrométrie de masse des protéines interagissant directement ou indirectement avec une séquence oligonucléotidique
No full textIdentifying transcriptional regulators of a gene of interest often represents a time- and work-consuming task, as currently used in silico analyses of DNA regulatory sequences are often disappointing, generating a lot of false positive and false negative candidates for further experimental validations. For these reasons, mass spectrometry-based identification of proteins captured by DNA-affinity methods have emerged these last years. However, these methods are challenging as they have to cope with the relatively low abundance of transcriptional regulators embedded in complex mixtures of highly expressed unspecific trapped proteins. Consequently, these methods are generally conducted with short DNA sequences by comparing proteins captured by a wild-type probe to the interactions detected with a mutated binding site. Although powerful, these approaches cannot be qualified as without “a priori” as they require pre-existing knowledge of the binding site of interest. In this work, we developped a straightforward procedure to detect, without “a priori”, a large panel of proteins interacting with a relatively long DNA sequence. As a proof of concept, a 226 bp-long sequence of the HIV-1 5’LTR promoter sequence was used as a bait, as this sequence is particularly well known and rich in transcription factor binding sites. The identification of NFB members among the interacting proteins was first used as a read out to set up the different parameters of the technique. This approach was then used to identify more than sixty proteins related to transcription, including 24 transcription factors and 38 transcriptional coregulators that interact indirectly with the DNA sequence. The presence of several transcription factors known to regulate the transcription of HIV-1 validated the technique, while the identification of 12 other transcription factors not previously described to be involved in the context of HIV-1 regulation underlines the advantage to conduct without “a priori” analyses. The interaction of two of these candidates with this regulatory sequence, Meis and PBX-1, has been functionally validated by analysing the effect of the mutated binding site on a HIV-1 5’LTR-dependent luciferase reporter assay. This allowed us to highlight the presence of a yet undescribed repressor binding site. Finally, using the DNA-affinity technique on a shorter DNA fragment centered on the Meis binding site, either wild-type or mutated, we could identify 7 members of the Sin3A complex as the coregulators responsible for the transcriptional repression associated with the Meis binding site.(DOCSC03) -- FUNDP, 201
Long term dynamics of space debris orbits including Earth's shadows
No full textA huge amount of space debris are currently orbiting the Earth. Understanding the motion of such uncontrolled objects is of great importance in order to reduce the risks of hypervelocity impacts with manned and unmanned spacecraft. In this work, we present an accurate symplectic integration scheme to numerically propagate space debris orbits over long periods of time. Among the perturbations that influence debris motion, this thesis mainly brings new results about the effects of solar radiation pressure on debris characterized by high area-to-mass ratios. In this case, Earth’s shadow crossings cannot be neglected. Hence we propose an innovative method that successfully models shadow crossings and does not break the symplectic properties of our propagator. Both cylindrical and conical shadows are considered. We show that the cylindrical model is only a poor approximation of the more realistic conical model, especially for high area-to-mass ratios. Thanks to both numerical and semi-analytical techniques, we then explain how shadow crossings are responsible for large periodic deviations from the initial condition. Finally an analysis is presented to highlight the strong influence of shadow crossings on the stability of high area-to-mass space debris located around the geostationary altitude.De très nombreux débris spatiaux sont actuellement en orbite autour de la Terre. Le risque permanent de collisions entre ces objets incontrôlables et les sondes spatiales actives (habitées ou non) requiert la connaissance précise de leur trajectoire. Cette thèse propose un intégrateur symplectique permettant de propager numériquement et rapidement les orbites des débris sur de longs intervalles de temps. Les perturbations agissant sur leurs trajectoires sont nombreuses. En particulier, la pression de radiation solaire devient prédominante pour les objets dont le rapport surface sur masse est important. Les passages dans l’ombre de la Terre ne peuvent alors plus être négligés. Ce travail présente une méthode innovante de modélisation de ces passages dans l’ombre (cylindrique ou conique) dont la formulation permet de conserver le caractère symplectique du propagateur. Les résultats prouvent qu’une ombre cylindrique représente une mauvaise approximation de la réalité, et préconisent une formulation conique, particulièrement pour les grands rapports surface sur masse. Des méthodes numérique et semi-analytique sont ensuite développées pour expliquer les importantes déviations périodiques (observées sur les orbites) provoquées par ces passages dans l’ombre, avec des périodes allant de 1 à 10000 ans. Enfin, une étude systématique de la stabilité autour de l’altitude géostationnaire prouve la présence de chaos, dont l’intensité et l’étendue sont renforcées par les passages dans l’ombre.(DOCSC00) -- FUNDP, 201
Production, diffusion et usages des recueils d'exempla latins aux XIIIe-XVe siècles
No full textThe exemplum is a privileged target for the cultural study of the medieval society. If the research regarding the content of those edifying anecdotes is already well advanced, the analysis of the real audiences and concrete uses of the exempla remained yet to be undertaken. Because the expansion and characterization of this typology is directly linked with the emergence of the collections of exempla, our investigation was based on this kind of works. To succeed with this project, we used the information existing in the manuscripts copies and in medieval booklists. With these two kinds of sources, we analysed books as physical objects (cover, writing, etc.), vehicles of culture (versions, surrounding works, etc.) and historical witness (purchase, legacies, etc.). The thesis focused on the following central questions: how did books of exempla diffused in time and space? Which works achieved success? Who were the owners of these books? How did they read and use them?
In the first part of our analysis, the theoretical one, historiographical and historical definitions of the exemplum and the collections of exempla have been clarified. This was indispensable because a large part of the scientific literature, especially in France, only considered the exemplum as a kind of story, which appeared in the twelfth century and was used by preachers in sermons to illustrate a salutary message. By saying so, they neglected the persuasive nature of the exemplum, confining it to a literary genre. In reality, the exemplum should be primarily considered as a rhetorical argument based on a deed or a word that happened in the past. Nevertheless, its persuasive power, which comes from its visual imagery, is especially effective when the case is told in the form of a story. This phenomenon is currently studied in the storytelling management, which uses stories to improve communication. In sum, the exemplum is an argument stemming from reality in the form of a story.
The history of the exemplum does not start with the mendicant orders, but within democracy and the rhetoric schools of Athena and later in Rome. With the emergence of Christianity, church fathers use it to fight against heretics and monks to share the spiritual experience of elders to novices. A pro domo use of the exempla appears with the creation of the new religious orders, first Cluny, then the Cistercians and finally the mendicants. The latter put exempla in theirs sermons to attract the attention of their audience, though not only. They use them in conversations, lectiones and also in didactic and moral treatises. This was no novelty: previous writers such as John of Salisbury in his Polycraticus uses it abundantly. If the years 1250-1350 are the magnificent era of the exemplum, since the second half of the 14th century, we can notice a decline of the exemplum, which becomes either an illustration, an allegory, or an open, facetious, entertaining or devote story.
As far as the books of exempla are concerned, for a long time scholars did not try to define them precisely. They looked at these collections only for the stories they contained. To their minds, an exempla collection was simply a book in which there were exempla. To make a necessary distinction between very differing books of exempla, we need to precise: a) the proportion of exempla; b) if the exempla are used by the authors as arguments or offered to the readers for rhetorical purposes; c) if there is an organizational system. Those questions successively allow distinguishing books of exempla from books with exempla, exempla treaties from exempla collections and exempla repositories.
Nonetheless, due to the fact that exemplum is not a genre but a function, it is very hard to define a clear corpus. The first important book of exempla comes from Roman Antiquity. The Facta et dicta memorabilia of Valerius Maximus was used as a text book for students in rhetoric. With the flourishing of monasticism, exempla collections of the Vitae patrum spread all over the Christian world, diffusing the good examples of the desert Fathers. In the beginning of the second millennium, religious orders continued this practice, but with the new will of putting their respective orders forward. The first alphabetical repositories of exempla appear at the end of the 13th century due to the necessity of preaching and of tidying up growing knowledge. However, alongside the existence of these collections of exempla made for preaching purposes, there are many others books and treaties of exempla, whose function is either to instruct, or to give the rules of social morality, or simply to edify readers.
The second part of the thesis puts the stress on the concrete diffusion and uses of the exempla collections. The investigation on the manuscript copies shows, inter alia, an increase in their number during the centuries (13 times more in the 15th than in the 13th century), the predominant place of the German area, especially in the 15th century, and the growing importance of the treatises of exempla, taking advantage on the repertories. With regards to the incunabula, we count 172 Latin and 74 vernacular editions of exempla collections before 1500. This mainly concerns repositories for the former when the latter contains almost exclusively treaties. The production of this edition starts in the years 1470, culminates in the years 1480 and declines at the end of the century. Geographically, we notice the same importance of the German speaking area, especially in the city of Strasbourg. At the second place we find Italy, which produces mainly antique exempla collections. For the manuscript copies as for the incunabula editions, we have to keep in mind that it exists huge differences of success between books of exempla.
The last chapter focuses on the diffusion and uses of the books of exempla written by the Dominicans, the biggest producer of such collections. We also see big discrepancies of success, owners and uses. For example, the Gerard of Frachet’s Vitas fratrum were mainly read in continental Europe by Dominicans and Canons regular to keep conventual order and morality, while the John Herolt’s Promptuarium exemplorum was used by different orders and persons in the German world for pastoral purposes and John of Bromyard’s Summa praedicantium was located in England in highly intellectual institutions, such as universities and big Benedictine monasteries. A collection of exempla can also have different readers and uses. Thomas of Cantimpre’s Bonum universale de apibus, written for conventual purposes, was also used either as a repertory of exempla for preaching or as a treaty of social morality. John of Cessoles’ Liber de moribus was not only read by preachers and pastors but also by lay people as spiritual lecture. Across the study of the different exempla collections, we notice many German 15th century manuscripts exclusively elaborated for pastoral uses. In these Priesterhandbücher we can find, next to exempla collections, sermons, artes predicandi, treaties on the Mass, explanation of the sacraments, the Ten Commandments and Credo.
Unlike a common vision of exempla collections produced and used within the preaching, this global study shows, on the one hand, the great diversity of production environments and aims intended by exempla compilers, as well as, on the second hand, an equally important variety concerning diffusion and real uses of such works.
Added to the thesis, there is an appendix of more than 300 pages presenting 68 Latin books of exempla, in which the characteristics of the work are exposed, the objectives of use pursued by the author, and the modalities of diffusion (including the list of manuscripts, medieval mentions, translations and editions).(DOCFILO02) -- FUNDP, 201
SOA Method Engineering Framework for process-oriented and model-driven SOA implementation with underlying models of abstraction
No full textAs situations for SOA implementation projects vary case-by-case, it is required to find a way to adapt the implementation method for SOA to organizations' context. We take the standpoint of a process-oriented, model-driven and top-down-oriented approach using a Method Engineering Framework including also a prototype of a tooling support.
Firstly, a model (here: SOA Domain Model) is required to summarize and generalize various aspects (here: SOA sub-domains) that must be covered in a model-driven and process-oriented SOA development project. The SOA Domain Model should summarize contents of available SOA Methods. This model may indeed narrow the communication gap that often exists between managers (business) and developers (IT) by providing them a common reference framework, concepts and vocabulary. This is particularly done by describing SOA Domains which include sub-domains and activities. Domains can be considered as clusters (e.g. SOA modelling) with sub-domains (e.g. SOA modelling notation). Each sub-domain includes a series of activities.
Secondly, it is required to think about a possibility to get an idea what range and how deep available SOA Methods are covering SOA domains. SOA Methods are very broad and the before identified domains and related SOA sub-domains could be a way to compare in a structured way SOA Methods and identify areas of strengths and weaknesses of these available SOA Methods.
Third, with the help of Method Engineering the necessary academic deepness is achieved by proposing a situational SOA Method. Other than the SOA Methods, the situational SOA Method is able to adapt to particular situation. A Configuration Process for SOA Situational Method should in general be able to describe the process of creating fragments and applying them in a specific situation. The problem of non-fitting SOA Methods to a specific situation can be avoided.
To achieve this, SOA method fragments should be created and formalized from available SOA Methods. With these SOA Method Fragments, a perfectly fitting SOA Method could be configured as only the relevant fragments are chosen that cope with situation for concrete SOA definition project.
Field trials should demonstrate applicability of the assembled generic method and show in detail the design rationales or decisions that have been taken for the specific implementation examples.(DOCSC06) -- FUNDP, 201
Du rôle du cuivre et de la protéine Prion dans le vieillissement cellulaire
No full textOn the role of copper and the Prion protein in cellular aging
In 1961, Prof. L. Hayflick lays the foundations of cellular aging with theory of replicative senescence. It was subsequently shown that stress can trigger a premature senescence, called Stress-induced premature senescence (SIPS). Since then, the list of actors involved in senescence is growing with a little consideration for metals.
Copper plays an important role in the living world as it is the catalyst for many biochemical reactions and may be involved in the structure and function of proteins. The importance of copper homeostasis during aging has been demonstrated in a filamentous fungus Podospora anserina. The results of this study provide new evidence suggesting that the link between copper homeostasis and aging can not be restricted to P. anserina, but is conserved.
The first part of this work showed that copper is involved in senescence of WI-38 human diploid fibroblasts(HDFs). Using different techniques, we showed for the first time at the cellular level, an accumulation of copper in FDHs during replicative senescence. We also showed that copper could play an active role in establishing the senescent phenotype. Indeed, incubation with an copper-enriched medium generates an oxidative stress,an antioxidant response but also the premature appearance of senescence markers. The latter phenomenon is dependent of the oxidative stress generated by copper and p38MAPK.
Another part of this work concerns the role of Prion protein (PrP) in senescence. We have shown that PrP is overexpressed in PBMC from elderly compared with young people, in HDFs in replicative senescence and in premature senescence induced by copper and other oxidative stresses. WI-38 HDFs incubated with copper-enriched medium showed an overexpression of PrP under its normal conformational form (PrPc) which is localized in both cytoplasm and nucleus. We showed that the invalidation of PrP expression by specific siRNAs already induces the appearance of premature senescence. This invalidation seems to increase ROS production and DNA damages. These results suggest that PrP plays a protective role against oxidative stress, DNA damages and senescence.
This work highlights the fact that metals such as copper can play a role in the mechanisms of senescence.Du rôle du cuivre et de la protéine Prion dans le vieillissement
cellulaire
En 1961, le Pr. L. Hayflick pose les bases du vieillissement cellulaire avec la découverte de la sénescence réplicative. Par la suite, il a été montré que différents stress peuvent déclencher l’apparition d’une sénescence prématurée, nommée Sénescence Induite Prématurément par les Stress (SIPS). Depuis, la liste d’acteurs impliqués dans la sénescence ne cesse de croître mais peu de recherches ont été réalisées sur le rôle des métaux dans la sénescence. Le cuivre joue un rôle important dans le monde du vivant car il est le catalyseur de nombreuses réactions biochimiques et peut être impliqué dans la structure et la fonction des protéines. L’importance de l’homéostasie du cuivre au cours du vieillissement a été démontrée chez un champignon filamenteux Podospora anserina. Les résultats de ce travail donnent de nouvelles indications qui suggèrent que le lien entre l’homéostasie du cuivre et le vieillissement ne peut être restreint à P. anserina, mais est conservé.
La première partie de ce travail a mis en évidence que le cuivre est impliqué dans la sénescence des fibroblastes diploïdes humains (FDHs) WI-38. En utilisant différentes techniques, nous avons montré, pour la première fois au niveau cellulaire, qu’une accumulation de cuivre apparaissait dans les FDHs en sénescence réplicative. Nous avons également montré que le cuivre pouvait jouer un rôle actif dans l’établissement du phénotype sénescent. En effet, une incubation avec un milieu enrichi en cuivre engendre un stress oxydatif, une réponse antioxydante mais aussi l’apparition prématurée de marqueurs de la sénescence. Ce dernier phénomène est dépendant du stress oxydatif généré par le cuivre et de p38MAPK.
Une autre partie de ce travail porte sur le rôle de la protéine Prion (PrP) dans la sénescence. Nous avons montré que PrP est surexprimée dans les PBMC (peripheral blood mononuclear cell) provenant de personnes âgées en comparaison avec des personnes jeunes, dans les FDHs en sénescence réplicative et en sénescence prématurée induite par le cuivre ou par d’autres stress oxydants. Les FDHs WI-38 incubés avec le milieu enrichi en cuivre
montrent une surexpression de PrP sous sa forme normale (PrPc) et localisée à la fois dans le cytoplasme et le noyau. Nous avons ensuite montré que l’invalidation de l’expression de PrP par siRNAs spécifiques engendre déjà à elle seule l’apparition de marqueurs de la sénescence. Cette invalidation semble également induire une augmentation de la production de ROS et des dommages à l’ADN. Ces résultats suggèrent que PrPc joue un
rôle dans la protection contre les stress oxydatif, les dommages à l’ADN et la sénescence.
Ce travail met en avant le rôle des métaux tels que le cuivre dans les mécanismes de la sénescence.(DOCSC03) -- FUNDP, 201