Interactions des protéines sanguines avec interfaces polymères modifiées

La séparation sélective des protéines et des cellules sanguines est d'une importance capitale pour traiter certaines maladies cibles et pour plusieurs applications médicales telles que la cicatrisation des plaies. Le défi consiste à fournir la technologie la plus efficace et la plus rentable qui puisse garantir cette séparation. Parmi de nombreuses autres technologies de séparation, les technologies membranaires se sont révélées être prometteuses. Cependant, leurs interactions non spécifiques avec les protéines les rendent vulnérables au bio-colmatage, ce qui limite leur application dans le domaine biomédical. Par conséquent, l'objectif de ce travail est de concevoir une technologie membranaire adaptée pour le dépistage des protéines sanguines en utilisant la modification de surface. Cette dernière est réalisée en déposant certains groupements fonctionnels sur la surface de la membrane, tels que des copolymères polystyrène-poly acrylique acide (PS-PAA) et polystyrène-polyéthylène glycol (PS-PEG), soit pour favoriser une interaction spécifique avec des protéines cibles ou pour réduire leur interaction non spécifique. Dans un premier temps, les interactions potentielles qui pourraient avoir lieu entre les brosses de PAA, PEG et certaines protéines abondantes dans le plasma telles que la sérum-albumine humaine (HSA) et la ƴ-globuline (IgG) ont été étudiées en solution en utilisant la Diffusion des rayons-X aux petits angles (Acronyme anglais : SAXS) combinée à la chromatographie. Ainsi, nous avons constaté que le PAA forme des complexes avec l'HSA dans certaines conditions physico-chimiques spécifiques de pH et de force ionique. Cette liaison HSA-PAA s'est ensuite révélée réversible en fonction du pH et de la force ionique du milieu, et il a été démontré que sa stœchiométrie était liée à la taille du PAA. En revanche, l'IgG n'a pas présenté le même comportement que l'HSA vis-à-vis du PAA, mais elle s'est avérée être partiellement agrégée. Quant au PEG, il n'a montré aucune interaction avec les deux protéines. Ensuite, la cartographie par spectroscopie infrarouge à transformée de Fourier (FTIR) a confirmé le succès de la modification de surface par dépôt de copolymères sur la surface de la membrane, bien que la distribution du copolymère y soit hétérogène. L'adsorption statique de l'HSA sur les membranes revêtues de PS-PAA s'est avérée également corrélée au pH et à la force ionique comme elle l'était en solution, alors que celle de l'IgG ne l'était pas. Ensuite, il a été démontré que l'adsorption de l'HSA sur la membrane recouverte de PS-PEG était réduite. Enfin, les expériences de filtration ont révélé la même tendance à l'adsorption de l'HSA en mode dynamique, même si la perméabilité de la membrane était réduite par l'augmentation de la taille des brosses de copolymères déposées sur la surface. Globalement, cette étude nous a permis de comprendre le comportement de certaines protéines sanguines abondantes au contact de certains groupes fonctionnels que ce soit en solution ou à l'interface d'une membrane modifiée.The selective separation of blood proteins and cells is of a major importance to address some target diseases and for several medical applications such as wound healing. The challenge is to provide the most efficient and cost-effective technology that can ensure that. Among many other technologies, membranes processes have been revealed as promising techniques. However, their nonspecific interactions with proteins make them prone to biofouling, which in turn limits their application in biomedical fields. Therefore, the aim of this work is to design tailored membrane for blood proteins screening via surface modification. This latter is performed by coating onto the membrane surface some functional groups such as polystyrene-poly acrylic acid (PS-PAA) and polystyrene-poly ethylene glycol (PS-PEG) copolymers, either to promote a specific interaction with target proteins or to reduce their non-specific interaction. First, the potential interactions that could take place between PAA, PEG brushes and some abundant proteins in plasma such as human serum albumin (HSA) and ƴ-globulin (IgG) have been investigated in solution using Small Angle X-ray Scattering (SAXS) combined to chromatography. Thus, PAA has been found to form complexes with HSA in some specific physicochemical conditions of pH and ionic strength. This HSA-PAA binding has then been revealed to be reversible depending on the pH and the ionic strength of the medium and its stoichiometry was shown to be related to the PAA size. Whereas IgG did not exhibit the same behaviour as HSA towards PAA, it was found to be partially aggregated in our conditions. PEG did not display any interaction with both proteins. After that, Fourier Transform Infrared spectroscopy (FTIR) mapping showed that surface modification of the membranes by copolymers coating was successful, although the distribution of copolymer was heterogeneous over the membrane surface. The static adsorption of HSA onto membranes coated with PS-PAA was found to be also correlated to the pH and ionic strength as it was in solution, while that of IgG was not. Then, the adsorption of HSA onto a membrane coated with PS-PEG has been shown to be mitigated. Eventually, filtration experiments disclosed the same trend of HSA adsorption in dynamic mode even though the membrane permeability was reduced by the increase of the size of the copolymers brushes deposited onto the surface. Overall, this study enabled us to understand the behaviour of some abundant blood proteins in contact of some functional groups either in solution or at the interface of a modified membrane

Backbone chemical shift assignments of human 14-3-3σ\sigma

14-3-3 proteins are a group of seven dimeric adapter proteins that exert their biological function by interacting with hundreds of phosphorylated proteins, thus influencing their sub-cellular localization, activity or stability in the cell. Due to this remarkable interaction network, 14-3-3 proteins have been associated with several pathologies and the protein-protein interactions established with a number of partners are now considered promising drug targets. The activity of 14-3-3 proteins is often isoform specific and to our knowledge only one out of seven isoforms, 14-3-3$\zeta$, has been assigned. Despite the availability of the crystal structures of all seven isoforms of 14-3-3, the additional NMR assignments of 14-3-3 proteins are important for both biological mechanism studies and chemical biology approaches. Herein, we present a robust backbone assignment of 14-3-3$\sigma$, which will allow advances in the discovery of potential therapeutic compounds. This assignment is now being applied to the discovery of both inhibitors and stabilizers of 14-3-3 protein-protein interactions

Algorithm of Remote Monitoring ECG Using Mobile Phone: Conception and Implementation

Researches in the medical remote monitoring at home have taken a great consideration and care in wireless communication these last years. The set of these researches is linked to the aging population and lack of infrastructures of reception for persons exposed to accident’s risks in their daily life or degradation of their health in short time. The principal objective is to permit a taking off for medical and social dependant people as aged ones, handicapped, in order to the adaptation with their environment domestically and make up their incapacities. In this case, it is indispensable to make a diagnostic in a real time and managed really the given data of patients between medical actors with the permanent security insurance of highly risky patients. Furthermore, the need to make a speed diagnostic of patients and to detect their health state with efficacy permits the gain of time in their taking off. The stakes of setting up such systems are numerous, so much for patients, medical staff and the society generally. So, it is useful to detect and prevent the occurrence of critical situations of a person at home, implying the transmission of message and alarms to actors concerned and ready to intervene in case of necessity. Our attention has been focused on the choice of a relevant work. It concerns an application on a mobile terminal (MIDlet) for monitoring patient in a non-hospital setting. This paper recalls a complete architecture of an economic wireless transmission system with the implementation of an effective algorithm, adapted to the mobile terminal, allowing to the doctor to have the results of analysis of ECG data wirelessly

Free surface flow over a triangular depression

Two-dimensional steady free-surface flows over an obstacle is considered. The fluid is assumed to be inviscid, incompressible and the flow is irrotational. Both gravity and surface tension are included in the dynamic boundary conditions. Far upstream, the flow is assumed to be uniform. Triangular obstruction is located at the channel bottom. In this paper, the fully nonlinear problem is formulated by using a boundary integral equation technique. The resulting integro-differential equations are solved iteratively by using Newton’s method. When surface tension and gravity are included, there are two additional parameters in the problem known as the Weber number and Froude number. Finally, solution diagrams for all flow regimes are presented.Publisher's Versio

Design and implementation of a Context-Aware Health Service Platform (CAHS)

Computers are no match to humans in deducing situational information from their environment and in using it in their interactions. The advent of the context-aware applications seems to offer a way out to the computer that is not context-sensitive. The context aware applications can adapt their behaviors according to the perceived context or situation, without explicit user intervention, thereby providing human-centric services. To simplify the complexity of developing applications, context aware framework, which introduces context awareness into the environment where the applications are executed, is highlighted to provide a homogeneous interface involving generic context management and adaptation solutions. This papier has focused on the design of Context-Aware Health Services (CAHS) platform, which provide a health applications framework embedded on mobile devices. Our proposed platform is capabilities for context manager and adaptations according to context changes. It is designed to base on the SOA principles for achieving a flexible and dynamic architecture

Evolutionary synthesis of optimal control policies for manufacturing systems

In this paper, evolution strategies are used to synthesise optimal control policies for manufacturing systems. The evolutionary procedure is illustrated by synthesising optimal control policies for a manufacturing system previously considered in the context of genetic synthesis. The performance of evolution strategies and that of genetic algorithms are compared in detail for this system, thus indicating that the evolutionary synthesis procedure is faster than the genetic synthesis procedure.published_or_final_versio