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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Mécanisme d'action antidépresseur rapide de la kétamine et de son principal métabolite (2R,6R)-hydroxynorkétamine : rôle de la balance excitation-inhibition chez la souris / Mechanism of the antidepressant-like effects of ketamine and its main metabolite (2R,6R)-hydroxynorketamine : role of the excitatory and inhibitory balance in mice

Pham, Thu Ha 30 March 2018 (has links)
Selon l'OMS, les troubles dépressifs majeurs (TDM) seront la 2ème cause d'incapacité dans le monde en 2020 et deviendront la 1ère en 2030. Les antidépresseurs classiques ont des effets thérapeutiques retardés et de nombreux patients sont résistants. La kétamine, antagoniste du récepteur N-methyl-D-aspartate (R-NMDA) du L-glutamate, possède un effet antidépresseur rapide chez les patients résistants à un traitement classique. Le mécanisme de cette activité étonnante n'est pas bien compris. En couplant la microdialyse intracérébrale à un test comportemental prédictif d'une activité antidépressive dans un modèle de souris BALB/cJ de phénotype anxieux, nous montrons que cette activité de la kétamine dépend de la balance excitation-inhibition entre les systèmes glutamate/R-NMDA et R-AMPA, GABA/R-GABAA, sérotonine du circuit cortex préfrontal/noyau du raphé. Nos résultats suggèrent également que ce serait la combinaison [kétamine-(2R,6R)-hydroxynorkétamine, son principal métabolite cérébral] qui porterait l'effet antidépresseur. Mes travaux de thèse contribuent à une meilleure compréhension de l'effet rapide antidépresseur de la kétamine. / According to the WHO, major depressive disorder (MDD) will be the second leading cause of disability in the world in 2020 and will become the first in 2030. Conventional antidepressant drugs have delayed therapeutic effects and many patients are resistant. Ketamine, an N-methyl-D-aspartate (NMDA-R) receptor antagonist of L-glutamate, exerts a rapid antidepressant effect in patients who are resistant to standard therapy. The mechanism of this amazing activity is not well understood. By coupling intracerebral microdialysis to a predictive behavioral test of antidepressant activity in a BALB/cJ mouse model with an anxious phenotype, we show that this ketamine activity is dependent on the excitation-inhibition balance between glutamate/NMDA-R and AMPA-R, GABA/GABAA-R, serotonin systems in the prefrontal cortex/raphe nucleus circuit. Our results also suggest that it would be the combination [ketamine-(2R,6R)-hydroxynorketamine, its main brain metabolite] that would carry the antidepressant effect. My thesis work pave the way for the development of new fast-acting antidepressant drugs.
2

INNOVATIVE PRODUCT DESIGN FOR SUSTAINABILITY ENHANCEMENT IN ALUMINUM BEVERAGE CANS BASED ON DESIGN FOR SUSTAINABILITY CONCEPTS

Liew, Jason Chun Tchen 01 January 2005 (has links)
A new methodology for innovative product development based on the application of sustainability principles for the entire life-cycle of a product and beyond is developed. This involves an analysis of multi-life cycle material flow leading towards perpetual life products, making it truly sustainable. In order to achieve the function of such a sustainable product, it has to fulfill the concept of 6R (Recover, Reuse, Recycle, Redesign, Reduce and Remanufacture), which are composed of 6 stages of material flow in a products life, as opposed to the traditional 3R (Reduce, Reuse, Recover) concept. We apply the 6R concept in designing a new aluminum beverage can with much enhanced sustainability factors, especially in recycling processes.
3

Polynomial continuation in the design of deployable structures

Viquerat, Andrew David January 2012 (has links)
Polynomial continuation, a branch of numerical continuation, has been applied to several primary problems in kinematic geometry. The objective of the research presented in this document was to explore the possible extensions of the application of polynomial continuation, especially in the field of deployable structure design. The power of polynomial continuation as a design tool lies in its ability to find all solutions of a system of polynomial equations (even positive dimensional solution sets). A linkage design problem posed in polynomial form can be made to yield every possible feasible outcome, many of which may never otherwise have been found. Methods of polynomial continuation based design are illustrated here by way of various examples. In particular, the types of deployable structures which form planar rings, or frames, in their deployed configurations are used as design cases. Polynomial continuation is shown to be a powerful component of an equation-based design process. A polyhedral homotopy method, particularly suited to solving problems in kinematics, was synthesised from several researchers' published continuation techniques, and augmented with modern, freely available mathematical computing algorithms. Special adaptations were made in the areas of level-k subface identification, lifting value balancing, and path-following. Techniques of forming closure/compatibility equations by direct use of symmetry, or by use of transfer matrices to enforce loop closure, were developed as appropriate for each example. The geometry of a plane symmetric (rectangular) 6R foldable frame was examined and classified in terms of Denavit-Hartenberg Parameters. Its design parameters were then grouped into feasible and non-feasible regions, before continuation was used as a design tool; generating the design parameters required to build a foldable frame which meets certain configurational specifications. Two further deployable ring/frame classes were then used as design cases: (a) rings which form (planar) regular polygons when deployed, and (b) rings which are doubly plane symmetric and planar when deployed. The governing equations used in the continuation design process are based on symmetry compatibility and transfer matrices respectively. Finally, the 6, 7 and 8-link versions of N-loops were subjected to a witness set analysis, illustrating the way in which continuation can reveal the nature of the mobility of an unknown linkage. Key features of the results are that polynomial continuation was able to provide complete sets of feasible options to a number of practical design problems, and also to reveal the nature of the mobility of a real overconstrained linkage.
4

Receptores de citocinas proinflamat?rias na pr?-ecl?mpsia

Castro, Patricia Ingrid Mac?do de 30 November 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-25T23:07:30Z No. of bitstreams: 1 PatriciaIngridMacedoDeCastro_DISSERT.pdf: 960843 bytes, checksum: 3369f0056a2e2ab1f071631a2015066a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-08-04T20:48:06Z (GMT) No. of bitstreams: 1 PatriciaIngridMacedoDeCastro_DISSERT.pdf: 960843 bytes, checksum: 3369f0056a2e2ab1f071631a2015066a (MD5) / Made available in DSpace on 2016-08-04T20:48:06Z (GMT). No. of bitstreams: 1 PatriciaIngridMacedoDeCastro_DISSERT.pdf: 960843 bytes, checksum: 3369f0056a2e2ab1f071631a2015066a (MD5) Previous issue date: 2015-11-30 / A pr?-ecl?mpsia ? uma doen?a que afeta 3-8% das mulheres gr?vidas. Os fatores de risco para essa doen?a n?o s?o completamente compreendidos, mas incluem desregula??o da resposta imune oriundos de defeitos na placenta??o, fatores ambientais e gen?ticos. O presente estudo teve como objetivo investigar associa??o varia??o na quantidade de receptores de citocinas pr?-inflamat?rias (IL-1R, IL-6R e TNF-?R) estariam envolvidos com a pr?-ecl?mpsia. Receptores de citocinas (IL-1R2, TNF-?R1 e IL-6R) foram avaliados em c?lulas mononucleares das gr?vidas normotensas (controle n=11) e gr?vidas com pr?-ecl?mpsia (PE, n=24). Mulheres com pr?-eclampsia tinham peso mais elevado no in?cio da gravidez (p=0.0171). Foi observado uma diminui??o de mon?citos cl?ssicos, mas n?o de mon?citos intermedi?rios e n?o-cl?ssicos na pr?-ecl?mpsia. A frequ?ncia dos receptores de citocinas proinflamat?rias IL-1R2, TNF-?R IL-6R aderidos a membrana das subpopula??es de mon?citos (cl?ssicos, intermedi?rios e n?o cl?ssicos) e linf?citos (CD3+CD4+ e CD3+CD8+) estavam diminu?das em pacientes com pr?-ecl?mpsia, quando comparados com gr?vidas normais. A redu??o na quantidade de receptores de citocinas IL-1R2, TNF-?R1 e IL-6R em mon?ciots e linf?citos pode ser um fator mantenedor do estado inflamat?rio na pr?-eclampsia. / Preeclampsia is a disease specific of human pregnancy that affects 3-8% of pregnant women, and it is one of the three leading causes of maternal mortality and morbidity. The disease is characterized by hypertension and proteinuria after the 20th week of gestation. The risk factors for this disease are not completely understood but appear to include dysregulation of the immune response arising from defects in placentation, environmental and genetic factors. This study aimed to determine whether the variation in the amount of proinflammatory cytokine receptors IL-1R2, IL-6R and TNF-?R1 would be involved in preeclampsia. They were recruited women with preeclampsia (n=24) and women who evolved during pregnancy without changes in blood pressure (n=12) were recruited. Clinical and laboratory data were collected. The cytokine receptors (IL-1R2, TNF-?R1 and IL-6R) were assessed in mononuclear cells isolated from peripheral blood using flow cytometry (Control = 8; PE = 24). C-reactive protein (CRP) was determined by CRP ultrasensitive method (Control = 7; PE = 18) was performed using sera pregnant women. Women with preeclampsia had higher weight at the beginning of the pregnancy (p=0.0171) and lower gestational age at delivery (0.0008). Classical monocytes were decreased in preeclampsia but not intermediate or non-classical monocytes. The frequency of IL-1R2 pro inflammatory cytokine receptors is decreased in women with PE only in the subpopulation of non-classical monocytes (p = 0.0011). TNF-?R1 receptor and IL-6R, had a decreased frequency in the three subpopulations of monocyte (classic, intermediate and non-classical) when compared to women with normal pregnancy. An increase in IL-1R2 receptor in TCD4+ lymphocytes, but a decrease in TNF-receptor and IL-6R in women with preeclampsia were found. No differences in the frequency of those receptors in CD3+/CD8+ in preeclampsia. There was no difference in C-reactive protein in preeclampsia. The reduction in the amount of IL-1R2, TNF- ?R1 and IL-6R monocytes and lymphocytes can be involved in the regulation of inflammation observed in preeclampsia, contributing to disease.
5

Passive Haptic Robotic Arm Design

Yilmaz, Serter 01 October 2010 (has links) (PDF)
The implant surgery replaces missing tooth to regain functionality and look of the normal tooth after dental operation. Improper placement of implant increases recuperation periods and reduces functionality. The aim of this thesis is to design a passive haptic robotic arm to guide dentist during the implant surgery. In this thesis, the optimum design of the 6R passive haptic robotic arm is achieved. The methodology used in optimization problem involves minimization of end-effector side parasitic forces/torques while maximizing transparency of the haptic device. The transparency of haptic device is defined as realism of forces generated by device in real world compared to forces in virtual world. The multivariable objective function including dynamic equations of 6R robotic arm is derived and the constraints are determined using kinematic equations. The optimization problem is solved using SQP and GA. The link lengths and other relevant parameters along with the location of tool path are optimized. The end-effector parasitic torques/forces are significantly minimized. The results of two optimization techniques have proven to be nearly the same, thus a global optimum solution has been found in the search space. Main contribution of this study is to take spatial nonlinear dynamics into consideration to reduce parasitic torques. Also, a mechanical brake is designed as a passive actuator. The mechanical brake includes a cone based braking system actuated by DC motor. Three different prototypes are manufactured to test performance of the mechanical brake. The final design indicates that the mechanical brake can be used as passive actuators.
6

Caractérisation d’un nouveau composé thérapeutique agissant comme antagoniste allostérique du récepteur de l’Interleukine-6 en vue de la prévention des naissances prématurées et permettant de protéger l’intégrité fœtale

Prairie, Elizabeth 08 1900 (has links)
La naissance prématurée (PTB), soit une naissance se produisant avant la 37e semaine de grossesse chez l’humain, est encore à ce jour l’une des principales causes de mortalité et de morbidité néonatales. En accord avec les études actuelles, la gravité des issues à la naissance est fortement liée à une perte de la fine régulation physiologique de facteurs inflammatoires durant la grossesse. Notamment, plusieurs données ont identifié qu’une fluctuation à la hausse des taux d'interleukine(IL)-6 dans les tissus gestationnels, liquide amniotique et le sang fœtal augmentait grandement le pronostic de naissance prématurée et de ses comorbidités associées. En plus de créer un environnement inflammatoire défavorable durant la gestation, IL-6 augmente aussi les protéines d’activation utérine (UAP), ayant pour effet de diminuer le temps de gestation. À ce jour, les traitements disponibles consistent principalement à arrêter les contractions à l’aide de tocolytiques. Conséquemment, ils ne s'attaquent pas directement à l'inflammation maternelle en amont sur le développement du fœtus. C’est dans cette optique que notre laboratoire a développé un peptidomimétique, nommé HSJ633 (633), inhibant sélectivement le récepteur d’IL-6 (IL-6R). Brièvement, la liaison d’IL-6 à IL-6R permet l’activation de la protéine accessoire du récepteur, gp130, générant la phosphorylation des protéines STAT3, Akt et de Erk1/2. En se liant de manière allostérique, 633 a l’avantage d’inhiber sélectivement la voie de STAT3, celle-ci affectant principalement la production de protéines de la phase aiguë. Ainsi, nous émettons l'hypothèse qu’IL-6 peut causer des dommages aux tissus fœtaux et que l'inhibition d’IL-6R à l'aide de 633 améliorera les conditions à la naissance tout en maintenant l'intégrité du tissu fœtal. Durant tout ce travail, nous avons confirmé notre hypothèse en utilisant un modèle d’inflammation anténatal en administrant du lipopolysaccharide (LPS) sur des souris gestantes vers la fin de leur période de gestation. Les résultats ont montré que le LPS raccourcissait le temps de gestation, réduisaient le poids à la naissance et la survie des souriceaux. Nous avons confirmé qu’IL-6 est un acteur important dans l’induction de la PTB et que son inhibition sélective est suffisante pour diminuer les effets délétères de l’inflammation. De plus, nous avons caractérisé l’effet protecteur de 633 en analysant la transcription de gènes et la synthèse de protéines clés dans les tissus maternels et gestationnels. Nous avons poursuivi davantage la caractérisation en révélant la présence de 633 au niveau du placenta, mais pas dans le fœtus. Ces résultats permettent de clarifier que 633 diminue l’inflammation directement au niveau placentaire et qu’il empêche les dommages subséquents de se répercuter dans le fœtus. En outre, nous avons établi que 633 réduit la morphologie anormale des poumons et des intestins de la progéniture induite par l'inflammation. Ensemble, nos données montrent que 633 a rétabli avec succès les issues à la naissance en augmentant le temps de gestation, la survie à la naissance et en préservant l'intégrité des organes du fœtus dans un modèle de PTB induite par le LPS. Ces découvertes soulignent l’importance d’IL-6 et révèlent l’efficacité́ pharmacologique in vivo d’un nouveau modulateur de l’IL-6R. Le 633 est un nouveau prototype thérapeutique prometteur pour la prévention de la PTB chez l’humain. / Preterm birth (PTB), which occurs before the 37th week of pregnancy in humans, is still one of the leading causes of neonatal mortality and morbidity. In agreement with current studies, the severity of birth outcomes is strongly associated with the loss of fine physiological regulation of inflammatory factors during pregnancy. Notably, several data have identified that upward fluctuation of interleukin (IL)-6 levels in gestational tissue, amniotic fluid, and fetal blood greatly increase the prognosis of preterm birth and its comorbidities. In addition to creating an adverse inflammatory environment during gestation, IL-6 also increases uterine activating protein (UAP), which results in decreased gestation time. To date, available treatments mainly consist of attempts to stop contractions with tocolytics. Consequently, they do not directly address the upstream maternal inflammation on the development of the fetus. To that end, our laboratory has developed a peptidomimetic, named HSJ633 (633), that selectively inhibits the IL-6 receptor (IL-6R). Briefly, binding of IL-6 to IL-6R allows activation of the receptor accessory protein, gp130, resulting in phosphorylation of STAT3, Akt and Erk1/2. By binding allosterically, 633 has the advantage of selectively inhibiting the STAT3 pathway, the latter mainly affecting the production of acute phase proteins. Thus, we hypothesize that IL-6 can cause fetal tissue damage and that inhibition of IL-6R with 633 will improve birth outcomes while also preserving the integritý of fetal tissue. Throughout this work, we confirmed our hypothesis using a model of antenatal inflammation by injecting lipopolysaccharide (LPS) into pregnant mice towards the end of their gestation period. The results showed that LPS shortened gestation time and reduced pup weight and survival. We confirmed that IL-6 is an important player in the induction of PTB and that its selective inhibition is sufficient to decrease the deleterious effects of inflammation. In addition, we characterized the protective effect of 633 by investigating gene transcription and key protein synthesis in maternal and gestational tissues. We further characterized the effect by revealing the presence of 633 in the placenta, but not in the fetus. These results clarify that 633 decrease inflammation directly in the placenta and prevents subsequent injury in the fetus. In addition, we found that 633 reduces inflammation-induced abnormal morphology of the lungs and intestines of the offspring. Taken together, our data show that 633 successfully restored birth outcomes by increasing gestation time, survival at birth, and preserving fetal organ integrity in an LPS-induced PTB model. These findings underscore the importance of IL-6 and unveil the in vivo pharmacological efficacy of a novel modulator of IL-6R. 633 is a promising new therapeutic prototype for the prevention of PTB in humans.
7

IL-17A induced response and synergy with otherproinflammatory cytokines in human endothelial cells

Salin, Julia January 2021 (has links)
Cardiovascular diseases are a broad group of diseases, such as heart attack and heart failureaffecting the cardiovascular system. The primary cause of cardiovascular diseases isatherosclerosis, and its progression is brought about by oxidative stress and a complex chronicinflammation reaction cascade. Of central importance are proinflammatory cytokines, regulatedby multiple factors, including interleukin (IL) 17A. This project aims to investigate the effectof IL-17A on the inflammatory response of human vascular endothelial cells by quantifyingchemokine C-X-C motif ligand-1 (CXCL1) release when exposed or not to otherproinflammatory mediators such as TNF-𝛼, IL-6 and IL-1β. To investigate this, humanumbilical cord endothelial cells were cultured and then stimulated with IL-17A alone or incombination with other cytokines, namely IL-6/sIL6R, IL-1β, or TNF-𝛼. After an appropriateincubation time following the stimulations, the supernatants of the cells were collected, and theamount of CXCL1 was analysed with ELISA or qPCR, respectively. At a lower concentration(10ng/ml), IL-17A failed to induce a significant level of CXCL1 release from endothelial cells.However, IL-17A + TNF-𝛼 (5ng/ml) greatly enhanced, higher than inductions from individualtreatments combined, level of CXCL1 release from endothelial cells. Furthermore, combiningIL-17A with IL-1β or IL-6 induced non-abundant and abundant upregulation in CXCL1 release,respectively. On transcription level, the amount of CXCL1 mRNA induced by IL-17A alonewas non-significant, but stimulation with TNF-𝛼 and IL-17A + TNF-𝛼 induced significantlyupregulated expression of CXCL1. In conclusion, we found that IL-17A induced synergeticrelease of CXCL1 in human vascular endothelial cells with TNF-𝛼. In addition, the synergisticimpact of IL-17A and TNF-𝛼 in terms of CXCL1 induction in vascular endothelial cells wasevident on a transcriptional level. Our data imply that combined blockage of IL-17A and TNF-𝛼 could have an enhanced therapeutic effect on vascular inflammation.
8

Achieving Complex Motion with Fundamental Components for Lamina Emergent Mechanisms

Winder, Brian Geoffrey 01 March 2008 (has links) (PDF)
Designing mechanical products in a competitive environment can present unique challenges, and designers constantly search for innovative ways to increase efficiency. One way to save space and reduce cost is to use ortho-planar compliant mechanisms which can be made from sheets of material, or lamina emergent mechanisms (LEMs). This thesis presents principles which can be used for designing LEMs. Pop-up paper mechanisms use topologies similar to LEMs, so it is advantageous to study their kinematics. This thesis outlines the use of planar and spherical kinematics to model commonly used pop-up paper mechanisms. A survey of common joint types is given, as well as an overview of common monolithic and layered mechanisms. In addition, it is shown that more complex mechanisms may be created by combining simple mechanisms in various ways. The principles presented are applied to the creation of new pop-up joints and mechanisms, which also may be used for lamina emergent mechanisms. Models of the paper mechanisms presented in Chapter 2 of the thesis are found in the appendix, and the reader is encouraged to print, cut out and assemble them. One challenge associated with spherical and spatial LEM design is creating joints with the desired motion characteristics, especially where complex spatial mechanism topologies are required. Hence, in addition to a study of paper mechanisms, some important considerations for designing joints for LEMs are presented. A technique commonly used in robotics, using serial chains of revolute and prismatic joints to approximate the motion of complex joints, is presented for use in LEMs. Important considerations such as linkage configuration and mechanism prototyping are also discussed. Another challenge in designing LEMs is creating multi-stable mechanisms with the ability to have coplanar links. A method is presented for offsetting the joint axes of a spatial compliant mechanism to introduce multi-stability. A new bistable spatial compliant linkage that uses that technique is introduced. In the interest of facilitating LEM design, the final chapter of this thesis presents a preliminary design method. While similar to traditional methods, this method includes considerations for translating the mechanism topology into a suitable configuration for use with planar layers of material.

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