Les virus sont au centre de problème de santé publique. En raison de l'apparition de nouveaux virus et pour certains de leur résistance aux traitements existants il est toujours d’actualité de développement de nouveaux agents antiviraux. En général, la stratégie de lutte contre les infections virales est basée sur la vaccination ou sur l'activité des petites molécules, interférant avec un ou plusieurs processus biologiques participant au cycle de vie du virus. Dans ce contexte, nous avons conçu et synthétisé des petites bibliothèques de molécules visant des propriétés anti-filovirus. Dans ce projet de recherche, nous avons mis l'accent sur le développement de composés ciblant la protéine Niemann-Pick C1, les protéases cathepsine et le processus de réplication. Lors du développement des inhibiteurs de Neimann-Pick C1 plus de 70 composés ont été synthétisés, portant le squelette pipérazine. Afin d'obtenir des inhibiteurs de cystéine cathepsines pouvant être impliqués dans la réplication du virus Ebola, nous avons synthétisé une petite bibliothèque de composés porteurs de groupement 1,3,5-triazine et possédant des activité de l’ordre du nanomolaire sur les cathepsines B, K, L et S. Enfin, pour inhiber la réplication du virus en ciblant SAH hydrolase, nous avons proposé une série de C-nucléosides carbocyclic ayant motif de 4-aza-7,9-dideazaadenosine. / The viruses cause the problem of public health. Due to the appearance of new viruses and their resistance to existing treatments there is still relevant to develop new antivirals. Generally, the strategy to combat viral infections is based on vaccination or on the activity of small molecules, interfering with one or more biological processes participating in virus life cycle. In this context, we took an effort to design and synthesize the library of small molecules possessing anti-filovirus properties. In this research project, we were focused on the developing of compounds targeting Niemann-Pick C1 protein, cathepsin proteases and replication process. In our effort into the development of the inhibitors of Neimann-Pick C1 we prepared the series of about 70 compounds, having in common the piperazine moiety. Diverse 1,4-N,N - substituents of piperazine, differencing in a size and shape were studied. In order to obtain efficient cysteine cathepsins inhibitors, we synthesized the small library of compounds bearing 1,3,5-triazine moiety. Finally, to inhibit the virus replication by targeting SAH hydrolase, we proposed the series of carbocyclic C-nucleosides having motif of 4-aza-7,9-dideazaadenosine.

Made available in DSpace on 2014-12-17T14:16:35Z (GMT). No. of bitstreams: 1 YamaraASM_DISSERT_Parcial.pdf: 1235608 bytes, checksum: 64be8e29311055ebff593313fa2f1681 (MD5) Previous issue date: 2013-07-04 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The extraction, chemical and structural characterization of a wide variety of compounds derived from plants has been a major source of bioactive molecules. Several proteases have been isolated in the plant kingdom, with numerous pharmacological and biotechnological applications. Among the proteases isolated from plants, are the fibrinogenolytic, with relevant application in the treatment of disorders in the coagulation cascade, in addition to potential use as a tool in clinical laboratories. In this study, in addition to evaluating the effects of the protein extract of Cnidoscolus urens (L.) Arthur (Euphorbiaceae) in the coagulation cascade also investigates the presence of antimicrobial activity and characterizes the proteolytic activity detected in this extract, aiming to determine their potential pharmacological and biotechnological application. In this way, crude protein extracts obtained from the leaves of C. urens in Tris-HCl 0.05M, NaCl 0.15M, pH 7.5, were precipitated in different concentrations of acetone, and assessed for the presence of proteolytic activity in azocase?na and fibrinogen. The most active fraction (F1.0) in these tests was chosen for assessment of biological activity and biochemical characterization. The A? chain and B? of fibrinogen were completely cleaved at a concentration of 0.18 ?g/?L of protein fraction in 4 minutes. Fibrinogenolytic activity presented total inhibition in the presence of E-64 and partial in the presence of EDTA. The fraction demonstrated coagulant activity in plasm and reduced the APTT, demonstrating acting on the factors coagulation of the intrinsic pathway and common, not exerting effects on the PT. Fibrinolytic activity on plasma clot was detected only in SDS-PAGE in high concentrations of fraction, and there were no defibrinating. Although several proteases isolated from plants and venomous animals are classically toxic, the fraction F1.0 of C. urens not expressed hemorrhagic nor hemolytic activities. Fraction F1.0 also showed no antimicrobial activity. In proteolytic activity on the azocasein, the optimal pH was 5.0 and optimum temperature of 60?C. The enzyme activity has been shown to be sensitive to the presence of salts tested, with inhibition for all compounds. The surfactant triton did not influence the enzyme activity, but the tween-20 and SDS inhibited the activity. In the presence of reducing agents increase in enzyme activity occurred, a typical feature of enzymes belonging to the class of cysteine proteases. Several bands with proteolytic activity were detected in zymogram, in the region of high-molecular-weight, which were inhibited by E-64. In this study, we found that C. urens presents in its constitution cysteine proteases with fibrinogenolytic and procoagulant activity, which may be isolated, with potential application in treatment of bleeding disorders, thrombolytic and clinical laboratory / A extra??o, caracteriza??o qu?mica e estrutural de uma grande diversidade de compostos derivados de plantas tem sido uma fonte importante de mol?culas bioativas. Diversas proteases t?m sido isoladas no reino vegetal, com in?meras aplica??es farmacol?gicas e biotecnol?gicas. Dentre as proteases isoladas de plantas, est?o as fibrinogenol?ticas, com relevante aplica??o no tratamento de dist?rbios na cascata da coagula??o, al?m do uso em potencial como ferramenta em laborat?rios cl?nicos. Neste trabalho, al?m de avaliar os efeitos do extrato prot?ico de Cnidoscolus urens (L.) Arthur, pertencente ? fam?lia Euphorbiaceae, na cascata de coagula??o, tamb?m se investigou a presen?a de atividade antimicrobiana e caracterizou a atividade proteol?tica detectada neste extrato, tendo como objetivo determinar sua potencial aplica??o farmacol?gica e biotecnol?gica. Desse modo, extratos prot?icos brutos obtidos das folhas de C. urens em tamp?o Tris-HCl 0,05M, NaCl 0,15M, pH 7,5, foram precipitados em diferentes concentra??es de acetona, e avaliados quanto a presen?a de atividade proteol?tica em azocase?na e fibrinog?nio. A fra??o mais ativa (F1.0) nestes testes foi escolhida para realiza??o de avalia??o de atividade biol?gica e caracteriza??o bioqu?mica. As cadeias A? e B? do fibrinog?nio foram completamente clivadas na concentra??o de 0.18 ?g/?L de prote?na da fra??o em 4 minutos. A atividade fibrinogenol?tica apresentou inibi??o total em presen?a de E-64 e parcial em presen?a de EDTA. A fra??o demonstrou atividade coagulante sobre o plasma e reduziu o tempo de tromboplastina parcial ativada, indicando atuar sobre os fatores da via intr?nseca e comum da coagula??o, n?o exercendo efeitos sobre o tempo de protrombina. A atividade fibrinol?tica sobre o co?gulo de plasma foi detectado apenas em SDS-PAGE em concentra??es elevadas da fra??o, e apesar da atividade fibrin(ogen)ol?tica, n?o foi observada atividade defibrinogenante in vivo. Apesar de v?rias proteases de plantas e animais pe?onhentos serem classicamente t?xicas, a frac??o F1.0 n?o expressou atividade hemorr?gica nem hemol?tica. A fra??o F1.0 tamb?m n?o demonstrou atividade antimicrobiana. Na avalia??o da atividade proteol?tica sobre a azocase?na, o pH ?timo de rea??o foi 5.0, e a temperatura ?tima igual a 60?C. A atividade enzim?tica demonstrou ser sens?vel ? presen?a dos sais testados, com inibi??o para todos os compostos. O tensoativo triton n?o influenciou a atividade enzim?tica, por?m o tween-20 e SDS inibiram tal atividade. Em presen?a de agentes redutores ocorreu aumento da atividade enzim?tica, caracter?stica t?pica de enzimas pertencentes ? classe das ciste?no proteases. Diversas bandas prot?icas com atividade proteol?tica foram detectadas em zimograma, na regi?o de elevada massa molecular, que foram inibidas por E-64. Neste trabalho, foi revelado que C. urens apresenta fra??o enriquecida com ciste?no-proteases que apresentam atividade fibrinogenol?tica e procoagulante, que podem ser isoladas, com potencial aplica??o no tratamento de dist?rbios hemorr?gicos, como trombol?tico e em laborat?rio cl?nico / 2020-01-01

O presente trabalho descreve o uso de eletrodos de carbono vítreo como eletrodo-base para modificação com hexacianoferratos de Fe (FeHCF), Co (CoHCF) e Ni (NiHCF) por meio da adsorção destes complexos utilizando a técnica de voltametria cíclica. Os eletrodos quimicamente modificados (EQMs) preparados por este método apresentam características diferenciadas tais como robustez e estabilidade ao longo das medidas eletroquímicas, além de boas propriedades redox. Os EQMs com FeHCF e NiHCF foram avaliados em função da sua atividade eletrocatalítica para a reação de oxidação do Ácido Ascórbico em solução de KCl 0,1 mol L-1 (pH 6,6). O EQM com CoHCF foi avaliado nas mesmas condições dos outros filmes, porém não apresentou uma diminuição no sobrepotencial de oxidação do Ácido Ascórbico. Embora não tenha apresentado uma resposta semelhante aos EQMs com FeHCF e NiHCF, o EQM com CoHCF apresentou a melhor sensibilidade da resposta de corrente de pico quando comparado aos demais. A fim de proporcionar a renovação da superfície do eletrodo foi avaliada a utilização de eletrodos de pasta de carbono modificada com FeHCF, CoHCF ou NiHCF. Os parâmetros de composição da pasta, o eletrólito suporte e o pH foram avaliados utilizando o EPCM com FeHCF por meio da técnica de voltametria cíclica e os parâmetros otimizados foram aplicados no uso dos EPCM com CoHCF e NiHCF. Para avaliar a sensibilidade na deteccção da L-Cisteína, do Glifosato e da N-Acetilcisteína, os EPCMs modificados foram submetidos a estudos com a técnica de voltametria de onda quadrada. Todos os analitos apresentaram resposta eletroquímica em todos os EPCMs, porém as melhores respostas foram para o FeHCF na presença de L-Cisteína, CoHCF na presença de Glifosato e NiHCF na presença de N-Acetilcisteína. Na presença de 1 x 10-8 mol L-1 dos analitos os EPCMs com hexacianoferratos apresentaram um boa resposta eletroquímica, embora não tenha sido possível observar uma linearidade entre o aumento da concentração dos analitos propostos e a corrente de pico. Essa sensibilidade demonstrada pelos EPCMs na presença de moléculas com grupos funcionais, como ácidos carboxílicos, aminoácidos e tióis abre novas perspectivas para a análise direta de compostos de interesse clínico, farmacêutico e amostras de interesse ambiental. / This work describes the use of glassy carbon electrodes as the base for electrode modification with hexacyanoferrates of Fe (FeHCF), Co (CoHCF) and Ni (NiHCF) through adsorption of these complexes using cyclic voltammetry. The chemically modified electrodes (CMEs) prepared by this method have specific features such as robustness and stability along the electrochemical measurements, and good redox properties. The CME with FeHCF and NiHCF were evaluated take into accounting their electrocatalytic activity for oxidation reaction of Ascorbic Acid in KCl 0.1 mol L-1 (pH 6.6). The CME with CoHCF was evaluated under the same conditions, but did not show a decrease on the overpotential for Ascorbic Acid oxidation. Although the CME with CoHCF has not showed the same behavior presented by CMEs with FeHCF and NiHCF, the CME with CoHCF presented the best sensitivity in order to relationship between peak current and concentration of Ascorbic Acid when compared to CMEs with either. In order to provide the renewal of the electrode surface was evaluated the use of carbon paste electrodes (CPEs) modified with FeHCF, CoHCF and NiHCF. The CPE parameters such as composition, supporting electrolyte and pH were evaluated using the CPE with FeHCF by cyclic voltammetry and these optimized parameters were applied for CPEs with CoHCF and NiHCF. The studies about the sensitivity of the detection for L-Cysteine, glyphosate and N-acetylcysteine using the modified CPEs with hexacyanoferrates were performed by square wave voltammetry. All analytes showed electrochemical response at all CPEs, but the best electrochemical responses were obtained for FeHCF in the presence of L-Cysteine, CoHCF in the presence of glyphosate and NiHCF in the presence of N-acetylcysteine. The CPEs with hexacyanoferrates in the presence of 1 x 10-8 mol L-1 of L-Cysteine, glyphosate or N-acetylcysteine had showed a good electrochemical response, although were not possible to observe a linear correlation between the concentration of analytes and peak current. This sensitivity demonstrated by CPEs with hexacyanoferrates electrodes in presence of specific functional groups such as carboxylic acids, amino acids and thiols opens new perspectives for the direct analysis of compounds with clinical, pharmaceutical and environmental samples.

Os cações são importantes recursos pesqueiros que podem apresentar concentrações de mercúrio (Hg) e arsênio (As) muitas vezes acima do limite de tolerância, o que os tornam impróprios como alimento. No meio aquático estes contaminantes são convertidos em espécies orgânicas, em especial metilmercúrio (MeHg) e arsenobetaína (AB), respectivamente. O MeHg é neurotóxico, sendo o sistema nervoso em desenvolvimento o mais susceptível. A AB é pouco tóxica, no entanto, o As inorgânico está envolvido em processos de estresse oxidativo, mutagênese e principalmente carcinogênese. Neste trabalho, foi avaliada a eficiência da cisteína na remoção de Hg, a ocorência de As total e inorgânico, e a redução de sua concentração com o emprego de borohidreto de sódio e de preparos para o consumo. A redução máxima de Hg, de 59,4%, com cisteína a 0,5% em pH 5,0, não foi reproduzida quando pretendida a reutilização da solução do aminoácido, importante do ponto de vista prático. O cação-azul continha elevados níveis de As total, 1,98 a 22,56 µg/g (base úmida), que foram removidos com borohidreto de sódio em 99%, demonstrando a alta potencialidade do método usado. O As inorgânico, presente na quantidade média de 0,0086 µg/g (base úmida), foi reduzido em 27,7%. O preparo para o consumo, por cozimento em água, do cação-azul em cubos (1-2 cm3), resultou em maior remoção de As total, de 65,9 a 71,2%; no cação grelhado a redução foi de 55,4 a 60,2%. As amostras, grelhadas ou cozidas, adicionadas de sal e limão enriquecido com ácido ascórbico, e as grelhadas contendo sal e sal com limão, apresentaram redução na concentração de As inorgânico de 30,1 a 42,8%. / The shark are important fishery resources that may have concentrations of mercury (Hg) and arsenic (As) often above the limit of tolerance, which makes them unsuitable as food. In the aquatic environment these contaminants are converted to organic species, particularly methylmercury (MeHg) and arsenobetaína (AB), respectively. The MeHg is neurotoxic, and the developing nervous system more susceptible. AB is slightly toxic, however, the inorganic As is involved in processes of oxidative stress, mutagenesis and carcinogenesis mainly. In this study, we evaluated the efficiency of cysteine to remove mercury, the occurrence of the total and inorganic As, and the reduction of their concentration with the use of sodium borohydride and preparations for consumption. The maximum reduction of Hg, 59.4%, with 0.5% cysteine at pH 5.0, was not reproduced when you want to reuse the solution of the amino acid, important practical point of view. The blue-shark contained high levels of the total As, 1.98 to 22.56 µg/g (wet weight), which were removed with sodium borohydride in 99%, demonstrating the high potential of the method used. The inorganic As, present in the average amount of 0.0086 µg/g (wet weight) was reduced in 27.7%. Preparation for consumption by baking in water, the blue-shark into cubes (1-2 cm3) resulted in greater removal of the total As, 65.9 to 71.2%; in the grilled shark the reduction was 55,4 to 60.2%. The samples, grilled or baked, added salt and lemon enriched with ascorbic acid, and the grilled containing salt and salt with lemon, presented reduction in the concentrations of inorganic As from 30.1 to 42.8%.

It is known that muscles that lack KATP channel activity generate much greater unstimulated [Ca2+]i and force than normal muscles during fatigue. The increase in unstimulated force in KATP channel deficient muscles is abolished by a partial inhibition of L-type Ca2+ channels, suggesting that it is due to a Ca2+ influx through L-type Ca2+ channels and a subsequent increased myoplasmic Ca2+. However, there is also evidence that the increase in resting force is abolished by NAC, a ROS scavenger. The objective of this study was to reconcile these observations by studying the hypothesis that “the increase in resting [Ca2+]i during fatigue in KATP channel deficient muscles starts with an excess Ca2+ influx through L-type Ca2+ channels, followed by an excess ROS production that causes a further increase in resting [Ca2+]i”. To test the hypothesis, single FDB fibres were fatigued with one tetanic contraction/sec for 180 sec. KATP channel deficient fibres were obtained i) by exposing wild type muscle fibers to glibenclamide, a KATP channel blocker and ii) by using fibres from Kir6.2-/- mice, which are null mice for the Kir6.2 gene that encodes for the protein forming the channel pore. Verapamil, a L-type Ca2+ channel blocker, applied at 1 μM, significantly reduced resting [Ca2+]i during fatigue in glibenclamide-exposed wild type fibres. NAC (1 mM) also reduced resting [Ca2+]i in glibenclamide-exposed muscles. The results suggest that the increase in resting [Ca2+]i during fatigue in KATP channel deficient FDB fibres is due to an influx through L-type Ca2+ channels, and an excess ROS production.

Les glutathion transférases (GSTs) constituent une superfamille ubiquitaire d’enzymes multifonctionnelles impliquées dans les processus de détoxication cellulaire en métabolisant des substrats exogènes appelés xénobiotiques et dans le métabolisme secondaire. Pour cela, ces enzymes peuvent catalyser la conjugaison d’une molécule de glutathion (GSH) sur les composés ciblés ou simplement les lier au travers d’une fonction ligandine. Alors que la fonction de conjugaison est catalysée par les GSTs possédant une sérine ou une tyrosine comme résidu catalytique, certaines d’entre elles possèdent à la place une cystéine. Cette substitution change radicalement leurs propriétés puisque les GSTs à cystéine (Cys-GSTs) catalysent plutôt des réactions de déglutathionylation. Les Cys-GSTs sont retrouvées chez la plupart des organismes et sont réparties en plusieurs classes. Chez les plantes, on trouve principalement 4 classes : déshydroascorbate réductases (DHARs), GSTs Lambda (GSTLs), glutathionyl hydroquinone réductases (GHRs) et mPGES2 (microsomal prostaglandine E-synthase type 2). Alors que le rôle des DHARs semble clairement associé à la réduction du déshydroascorbate en ascorbate, la fonction physiologique des autres Cys-GSTs reste majoritairement inconnue. En combinant des approches moléculaires, cellulaires, biochimiques et structurales, l’analyse fonctionnelle des deux GHRs, des trois GSTLs et des trois DHARs chez l’arbre modèle Populus trichocarpa a été entreprise. De façon intéressante, les gènes GSTL et GHR sont majoritairement exprimés dans les fleurs, les fruits et les pétioles par rapport aux feuilles et aux racines. A l’inverse, les gènes DHAR sont principalement exprimés dans les feuilles. De plus, l’expression transitoire de protéines fusionnées à la GFP dans le tabac a montré que les GSTLs et les DHARs sont localisées dans les plastes, le cytoplasme et le noyau alors que les GHRs sont toutes plastidiales. Les études biochimiques et structurales effectuées à l’aide des protéines recombinantes et de substrats modèles ont montré que la plupart des Cys-GSTs possèdent des activités et des structures assez semblables. Cependant, bien que les GSTLs et les DHARs adoptent un repliement GST canonique classique proche de celui des GSTs Oméga fongiques et humaines, elles sont monomériques alors que les GSTs Oméga sont dimériques. Les GHRs sont particulières tant au niveau de leur interface de dimérisation unique qu’au niveau de leurs propriétés spécifiques de réduction de quinones glutathionylées. En résumé, la nature des substrats fixés par les Cys-GSTs (composés cycliques aromatiques) ainsi que les territoires d’expression de ces gènes et protéines suggèrent que ces protéines sont globalement impliquées dans la protection des plantes face aux contraintes environnementales via la modification, le stockage et/ou le transport de métabolites secondaires et autres composés antioxydants. Toutefois, l’objectif suivant sera de déterminer la nature exacte des substrats/ligands associés à chaque enzyme / Glutathione transferases (GSTs) constitute a ubiquitous superfamily of multifunctional enzymes involved in cellular detoxification processes by metabolizing exogenous substrates called xenobiotics and in secondary metabolism. For this purpose, these enzymes catalyze the conjugation of a glutathione molecule (GSH) onto target compounds or simply bind them through a ligandin function. While conjugation reactions are catalyzed by GSTs having a serine or a tyrosine as catalytic residues, other GSTs possess a cysteine. This substitution radically changes their properties since GSTs having a cysteine (Cys-GSTs) rather catalyze deglutathionylation reactions. Cys-GSTs are found in most organisms and are divided into several classes. In plants, there are mainly four classes: dehydroascorbate reductases (DHARs), Lambda GSTs (GSTLs), glutathionyl hydroquinone reductases (GHRs), and microsomal prostaglandin E-synthase type 2 (mPGES). While the role of DHARs seems clearly associated to the reduction of dehydroascorbate into ascorbate, the physiological function of other Cys-GSTs remains largely unknown. By combining molecular, cellular, biochemical and structural approaches, the functional analysis of the two GHRs, the three GSTLs and the three DHARs in the model tree Populus trichocarpa was undertaken. Interestingly, GSTL and GHR genes are predominantly expressed in flowers, fruits and petioles compared to leaves and roots. Conversely, the DHAR genes are mainly expressed in leaves. Furthermore, transient expression of proteins fused to GFP in tobacco showed that GSTLs and DHARs are localized in plastids, cytoplasm and nucleus while GHRs are all localized in plastids. Biochemical and structural studies using recombinant proteins and model substrates showed that most Cys-GSTs have similar activities and structures. However, although GSTLs and DHARs adopt a canonical GST folding similar to that of fungal and human Omega GSTs, they are monomeric whereas Omega GSTs are dimeric. GHRs are particular owing to their unique dimerization interface and to their specific capacity to reduce glutathionylated quinones. In summary, the nature of the substrates bound by Cys-GSTs (heterocyclic aromatic compounds) as well as the expression territories of these genes and proteins, suggest that they are generally involved in the protection of plants towards environmental constraints through the modification, storage and/or transport of secondary metabolites and other antioxidants. However, the next goal will be to determine the exact nature of the substrates/ligands associated with each enzyme

The formation and patterns of a monolayer are determined by the interplay of two fundamental interactions, adsorbate-substrate and intermolecular interactions. The binding strength between adsorbate and substrate affects the mobility of the adsorbate at the surface and the stability of the complex. The intermolecular interaction plays a significant role in the monolayer patterns on the epitaxial layer of the substrate. A monolayer can be formed either by a spontaneous self-assembly, or by fabrication via atomic-layer deposition (ALD). The physical and chemical properties of the resulting monolayer have a broad array of applications in fabricating functional materials for hydrophobic or hydrophilic surfaces, biological sensors, alternating the properties of the substrate, catalysis and forming ordered layered structures. In this dissertation, the investigation focuses primarily on the influence of the surface topology on the binding behaviour of adsorbate-surface complexes. The state of the art DFT-TS method is used to simulate the sulfur-containing amino acids at complex gold surfaces and examine the relationship between the binding strengths and the binding sites with various nearest neighbouring environments. The same method is also used to determine if a chemical reaction will take place for various catalytic silicon precursors at a silicon oxide surface. Simulating surface chemistry using the DFT-TS method requires intensive com- puting resources, including CPU use and computing time. Another focus of this dissertation is to increase the data generating speed by reducing the size of the sim- ulated systems without altering the outcome. A relatively small gold cluster is used to study the binding behaviours of small organic molecules on the cluster. The same strategy is also used to simulate the chemical reactions between various self-catalying silicon precursors and a water molecule. / Graduate / 2021-10-21

No description available.

Helminth neuroinfections represent a serious health issue, but the mechanisms of the host immune response often remain neglected despite the fact they might contribute to pathogenesis. This is partly due to the unavailability of clinical samples and the lack of suitable laboratory models. Herein, I focused on the characterization of several aspects of the immune response of mice infected with the neuropathogenic avian schistosome Trichobilharzia regenti. After the percutaneous infection of mice (accidental hosts), most T. regenti schistosomula are entrapped and eliminated in the skin, but the parasite antigens initiating the protective immune reaction are not known. Our in vitro experiments revealed that T. regenti cathepsin B2, a cysteine peptidase used for the skin penetration, activates bone marrow-derived dendritic cells much stronger than the parasite homogenate, suggesting its role in initiating the mixed type1/2 host immune response. However, some schistosomula manage to escape from the skin and continue their migration to the spinal cord. Here they crawl preferentially within the white matter which we demonstrated by the robust 3D imaging techniques, ultramicroscopy and micro-CT. The invasion of the spinal cord is accompanied by striking hypertrophy of astrocytes and microglia. We showed...

The present thesis work is dedicated to the implementation of novel electrochemical methods for the assay of drug compounds such as paracetamol and ascorbic acid and biologically relevant biothiols such as cysteine and glutathione. Particular attention has been paid to the development and application of amperometric detectors allowing for a readily surface renewing and for highly selective and sensitive assays.<p>Coupling of a screen printed electrochemical detector with a monolithic chromatographic column was performed for high-throughput analysis along with selectivity, sensitivity and good precision. The modification of a glassy carbon electrode with a perm-selective membrane was investigated in order to provide an electrochemical sensor for on-site analysis. Acetaminophen was investigated as a model drug compound because of its extensive use in drug “pain killer” medication.<p>Along with the aims of this thesis, a silver polycrystalline electrode was investigated as a sensitive and class selective electrode for the assay of small thiol-based molecules. The silver electrode was implemented for the first time as an amperometric detector coupled to liquid chromatography for the assay of thiols. Application to the study of thiol species present in white wines was realized in order to illustrate the potential of the silver working electrode as amperometric detector. / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished