L'activité volcanique peut représenter une source naturelle de pollution atmosphérique. Cette pollution peut engendrer une dégradation de la qualité de l'air, affecter la santé humaine et perturber la sécurité aérienne. Le Piton de la Fournaise à La Réunion est l'un des volcans basaltique les plus actifs au monde. Ses éruptions sporadiques génèrent des panaches volcaniques essentiellement constitués de gaz et de nanoparticules qui se propagent dans l'atmosphère. En journée, la formation d'oxydants (photolyse) permet d'oxyder une partie du dioxyde de soufre en acide sulfurique. Les molécules d'H2SO4 peuvent réagir avec les molécules d'eau atmosphérique pour former des embryons via la nucléation binaire homogène. Puis, ces embryons grossissent grâce aux processus de condensation et/ou coagulation conduisant alors à la formation d'un aérosol volcanique submicronique. Cette thèse vise à observer, comprendre et modéliser les processus de Formation de Nouvelles Particules (FNP) au sein des panaches volcaniques. De ce fait, elle s'organise en deux parties. La première se base sur les données recueillies lors de la campagne multidisciplinaire STRAP menée à l’observatoire du Maïdo et au Piton de la Fournaise en 2015. Elle expose les résultats issus d’une double analyse de la fréquence et de l’intensité des événements de FNP à l’observatoire. Tandis que la première analyse s’intéresse aux processus en l’absence du panache volcanique, la seconde met en exergue les spécificités de la FNP liées à sa présence au Maïdo. La seconde partie s'axe autour de la modélisation d'abord 0D puis 3D des processus de FNP au sein des panaches volcaniques via le modèle atmosphérique Méso-NH. / Volcanic activity can be a natural source of air pollution. This pollution can lead to a deterioration in air quality, affect human health and disrupt aviation safety. The Piton de la Fournaise in Reunion Island is one of the most active basaltic volcanoes in the world. Its sporadic eruptions generate volcanic plumes consisting mainly of gases and nanoparticles that spread in the atmosphere. During the day, a part of the sulphur dioxide can be oxidized to sulphuric acid thanks to oxidants production (photolysis). H2SO4molecules tend to react with atmospheric water molecules and form clusters via homogeneous binary nucleation. Then, these clusters grow by condensation and/or coagulation processes leading to the formation of a submicronic volcanic aerosol. This thesis aims to observe, understand and model the New Particle Formation (NPF) processes within volcanic plumes. Consequently, it is organized in two parts. The first is based on the data gathered during the multidisciplinary STRAP campaign conducted at both the Maïdo Observatory and Piton de la Fournaise volcano in 2015. It presents the results from a dual analysis of the NPF events frequency and intensity at the observatory. While the first analysis focuses on processes in the absence of the volcanic plume, the second highlights the specificities of the NPF related to the presence of the plume at Maïdo. The second part focuses on 0D then 3D NPF processes modelling within volcanic plumes via the Meso-NH atmospheric model.

Les fibres de carbone sont actuellement utilisées dans les matériaux composites pour les secteurs de l'aérospatiale, l’aéronautique et les sports de compétition. Leur application sur les marchés de grande consommation est toutefois entravée par le coût élevé des matières premières et le procédé de carbonisation, notamment l’étape de stabilisation. Par conséquent,les matériaux précurseurs alternatifs et peu coûteux sont très demandés. La lignine, une ressource naturelle très abondante contenant de grandes quantités de carbone, est considérée comme un bon candidat. Jusqu'à présent, les fibres de lignine ont été principalement préparées par filage en voie fondue et en mélange avec des polymères thermoplastiques pour améliorer leur aptitude au filage et leurs propriétés mécaniques, mais en réduisant fortement leurs rendements de carbonisation et en augmentant leur prix. Nous proposons dans cette thèse des fibres précurseur à base de lignine obtenues par un procédé de filage en continu par coagulation. En combinaison avec de petites proportions d'alcool polyvinylique, on obtient des fibres composites hautement flexibles et infusibles, contenant jusqu'à 70-90 % de lignine industrielle. Notre développement nous permet de fabriquer des fibres de carbone avec des rendements de l’ordre de 30 % qui présentent des propriétés prometteuses. Jusqu'à présent, les fibres de carbone à base de lignine mentionnées dans la littérature n'atteignent pas les propriétés mécaniques requises pour des applications à hautes performances en raison de leur structure de carbone amorphe. Cependant, en incorporant des cristaux liquides de feuillets d'oxyde de graphène ou des nanocristaux de cellulose dans nos fibres précurseurs de lignine, nous pouvons améliorer l'orientation des plans de carbone obtenus après la carbonisation. Nos systèmes de fibres à base de lignine avec une structuration améliorée représentent donc une étape importante vers la mise en oeuvre industrielle de la lignine en tant que matériau précurseur «vert» pour les fibres de carbone à faible coût et à haute résistance. / Carbon fibres are currently used in composite materials for the aerospace, transportation and energy sectors. Their application in mass markets however is hindered by the high cost of the fibre raw materials. Therefore, alternative and inexpensive precursor materials are in high demand. Especially lignin, a widely abundant natural resource containing high quantities of carbon, is considered as an important candidate. So far, lignin fibres have mostly been prepared by melt-spinning and by blending with thermoplastic polymers to enhance their spinnability and mechanical properties, but strongly lowering their carbonization yields and raising their price. We propose lignin-based precursor fibres obtained through a continuous wet-spinning process. In combination with only small ratios of polyvinyl alcohol, highly flexible and infusible composite fibres, containing up to 70-90 % of industrial lignin, can be obtained.Our development enables us to manufacture carbon fibres in high yields which exhibit promising properties. Until now, lignin-based carbon fibres reported in literature do not reach the mechanical properties required for high-performance applications due to their amorphous carbon structure. However, by incorporation of liquid crystalline graphene oxide flakes or cellulose nanocrystals into our lignin precursor fibres, we are able to improve the orientation of the carbon planes obtained after carbonization. Our lignin-based fibre systems with enhanced structuration thus represent an important step towards the industrial implementation of lignin as “green” precursor material for low-cost and high-strength carbon fibres.

Introdução: Pacientes com cirrose possuem altos níveis de fator VIII e preservação da trombomodulina (TM) (ativador da proteína C) apesar da redução global nas concentrações dos procoagulantes e anticoagulantes naturais. Isto não é levado em conta no teste de TP/INR, o qual não requer a adição de trombomodulina. Deste modo, o TP/INR não é capaz de demonstrar a magnitude da geração de trombina, em condições similares à que ocorre in vivo. De fato, o teste de TP/INR mede o lado procoagulante e se correlaciona com somente 5% do total de trombina gerada. Nossa hipótese é que a geração de trombina está bem preservada na cirrose, ainda que avançada, apesar dos resultados anormais do TP/INR, os quais indicariam coagulopatia. Objetivo: correlacionar os resultados do teste TP/INR com a geração de trombina nos pacientes com cirrose após procedimento invasivo (ligadura elástica de varizes esofagianas - LEVE). Pacientes e métodos: 97 pacientes foram consecutivamente incluídos no estudo (58 homens; 54±10 anos) e divididos em dois grupos INR < 1,5 e INR >= 1,5. Todos os pacientes passaram por uma criteriosa análise clínica e laboratorial, que incluiu revisão dos prontuários, determinação do TP/INR e da geração de trombina (ETP) com e sem adição de trombomodulina e cálculo do rETP (razão dos resultados com e sem adição de trombomodulina). Resultados: Não houve diferença significante na média dos valores de ETP sem trombomodulina no grupo INR < 1,5 (n=72), que foi 1.250±315,7 nmol/min quando comparada ao grupo INR >= 1,5 (n=25), cujos valores foram 1.186±238 nmol/min, p=0,3572. Após adição de trombomodulina, os valores mudaram para 893,0±368,6 e 965,9±232,3 nmol/min, respectivamente (p=0,6265). Ambos os grupos apresentaram preservação da geração de trombina, com valores mais elevados no grupo INR >= 1,5 do que no grupo de pacientes com INR < 1,5 (rETP 0,81±0,1 versus 0,69±0,2; p=0,0042). Evidência de hipercoagulabilidade (valores altos de rETP) foi demonstrada em 80% dos pacientes. Mesmo pacientes com INR >= 1,5 apresentam geração de trombina preservada, o que justificaria a baixa prevalência de sangramento após ligadura elástica de varizes esofagianas (5,2%; 3 pacientes no grupo INR < 1,5 e 2 pacientes no grupo INR >= 1,5). Conclusões: a geração de trombina se encontrou preservada nos pacientes com cirrose e os valores anormais de INR não refletiram a ocorrência de sangramento. A maioria dos pacientes mostrou evidência de hipercoagulabilidade, apesar do INR alargado. Sangramento após LEVE ocorreu em pequena parcela dos pacientes e não foi relacionado ao status da coagulação / Introduction: Patients with cirrhosis have higher levels of factor VIII and preservation of endothelial thrombomodulin (protein C activator) in spite of the global reduction in procoagulant and natural anticoagulant concentrations. This is not taken into account in the laboratory test of INR/PT, which does not require the addition of thrombomodulin and, thus, is not able to emulate the generation of thrombin that happens in vivo. In fact, INR/PT is a measure of procoagulant status and correlates with only 5% of the total amount of generate thrombin. We hypothesized that thrombin generation is well preserved in cirrhosis, even in advanced stages, despite the abnormal result of INR/PT, which would indicate coagulopathy. Aims: to correlated INR/PT with thrombin generation in patients with cirrhosis in the elective setting of an invasive procedure (endoscopic variceal ligation- EVL). Patients and Methods: 97 consecutive patients were prospectively included in this study (58 men; 54±10 years old) and divided into two groups INR < 1.5 and INR >= 1.5. All patients underwent a stringent clinical and laboratory assessment which included review of the clinical chart, INR/PT determinations and assessment of endogenous thrombin potencial (ETP) without and with the addition of thrombomodulin and calculation of the ETP ratio (rETP= without/with thrombomodulin). Results: There was no significant difference in the mean value of ETP without thrombomodulin that was 1,250±315.7nmol/min for patients with INR < 1.5 (n=72) and 1,186±238 in those with INR >= 1.5 (n=25); p= 0.3572. After the addition of thrombomodulin, values changed to 893.0±368.6 and 965.9±232.3, respectively (p= 0.6265). Both groups had preserved thrombin generation, which was higher in patients with INR >=1.5 than in patients with INR < 1.5 (rETP 0.81±0.1 versus 0.69±0.2; p=0.0042). Evidence of hypercoagulability (high rETP) was demonstrated in 80% of patients. Even patients with INR >= 1.5 had preserved thrombin generation, which is likely to account for the low prevalence of post-EVL bleeding (5.2%; n=3 with INR < 1.5 and n=2 with INR >= 1.5). Conclusions: thrombin generation was well preserved in patients with cirrhosis and was not reflected by abnormal results of INR. Most of the patients had evidence of hypercoagulability, despite enlarged INR. Post-procedure bleeding occurred in a small subset of the patients and was not related to the coagulation status

Introdução: Pacientes com cirrose possuem altos níveis de fator VIII e preservação da trombomodulina (TM) (ativador da proteína C) apesar da redução global nas concentrações dos procoagulantes e anticoagulantes naturais. Isto não é levado em conta no teste de TP/INR, o qual não requer a adição de trombomodulina. Deste modo, o TP/INR não é capaz de demonstrar a magnitude da geração de trombina, em condições similares à que ocorre in vivo. De fato, o teste de TP/INR mede o lado procoagulante e se correlaciona com somente 5% do total de trombina gerada. Nossa hipótese é que a geração de trombina está bem preservada na cirrose, ainda que avançada, apesar dos resultados anormais do TP/INR, os quais indicariam coagulopatia. Objetivo: correlacionar os resultados do teste TP/INR com a geração de trombina nos pacientes com cirrose após procedimento invasivo (ligadura elástica de varizes esofagianas - LEVE). Pacientes e métodos: 97 pacientes foram consecutivamente incluídos no estudo (58 homens; 54±10 anos) e divididos em dois grupos INR < 1,5 e INR >= 1,5. Todos os pacientes passaram por uma criteriosa análise clínica e laboratorial, que incluiu revisão dos prontuários, determinação do TP/INR e da geração de trombina (ETP) com e sem adição de trombomodulina e cálculo do rETP (razão dos resultados com e sem adição de trombomodulina). Resultados: Não houve diferença significante na média dos valores de ETP sem trombomodulina no grupo INR < 1,5 (n=72), que foi 1.250±315,7 nmol/min quando comparada ao grupo INR >= 1,5 (n=25), cujos valores foram 1.186±238 nmol/min, p=0,3572. Após adição de trombomodulina, os valores mudaram para 893,0±368,6 e 965,9±232,3 nmol/min, respectivamente (p=0,6265). Ambos os grupos apresentaram preservação da geração de trombina, com valores mais elevados no grupo INR >= 1,5 do que no grupo de pacientes com INR < 1,5 (rETP 0,81±0,1 versus 0,69±0,2; p=0,0042). Evidência de hipercoagulabilidade (valores altos de rETP) foi demonstrada em 80% dos pacientes. Mesmo pacientes com INR >= 1,5 apresentam geração de trombina preservada, o que justificaria a baixa prevalência de sangramento após ligadura elástica de varizes esofagianas (5,2%; 3 pacientes no grupo INR < 1,5 e 2 pacientes no grupo INR >= 1,5). Conclusões: a geração de trombina se encontrou preservada nos pacientes com cirrose e os valores anormais de INR não refletiram a ocorrência de sangramento. A maioria dos pacientes mostrou evidência de hipercoagulabilidade, apesar do INR alargado. Sangramento após LEVE ocorreu em pequena parcela dos pacientes e não foi relacionado ao status da coagulação / Introduction: Patients with cirrhosis have higher levels of factor VIII and preservation of endothelial thrombomodulin (protein C activator) in spite of the global reduction in procoagulant and natural anticoagulant concentrations. This is not taken into account in the laboratory test of INR/PT, which does not require the addition of thrombomodulin and, thus, is not able to emulate the generation of thrombin that happens in vivo. In fact, INR/PT is a measure of procoagulant status and correlates with only 5% of the total amount of generate thrombin. We hypothesized that thrombin generation is well preserved in cirrhosis, even in advanced stages, despite the abnormal result of INR/PT, which would indicate coagulopathy. Aims: to correlated INR/PT with thrombin generation in patients with cirrhosis in the elective setting of an invasive procedure (endoscopic variceal ligation- EVL). Patients and Methods: 97 consecutive patients were prospectively included in this study (58 men; 54±10 years old) and divided into two groups INR < 1.5 and INR >= 1.5. All patients underwent a stringent clinical and laboratory assessment which included review of the clinical chart, INR/PT determinations and assessment of endogenous thrombin potencial (ETP) without and with the addition of thrombomodulin and calculation of the ETP ratio (rETP= without/with thrombomodulin). Results: There was no significant difference in the mean value of ETP without thrombomodulin that was 1,250±315.7nmol/min for patients with INR < 1.5 (n=72) and 1,186±238 in those with INR >= 1.5 (n=25); p= 0.3572. After the addition of thrombomodulin, values changed to 893.0±368.6 and 965.9±232.3, respectively (p= 0.6265). Both groups had preserved thrombin generation, which was higher in patients with INR >=1.5 than in patients with INR < 1.5 (rETP 0.81±0.1 versus 0.69±0.2; p=0.0042). Evidence of hypercoagulability (high rETP) was demonstrated in 80% of patients. Even patients with INR >= 1.5 had preserved thrombin generation, which is likely to account for the low prevalence of post-EVL bleeding (5.2%; n=3 with INR < 1.5 and n=2 with INR >= 1.5). Conclusions: thrombin generation was well preserved in patients with cirrhosis and was not reflected by abnormal results of INR. Most of the patients had evidence of hypercoagulability, despite enlarged INR. Post-procedure bleeding occurred in a small subset of the patients and was not related to the coagulation status

No description available.

INTRODUÇÃO: a albumina sérica reduzida em pacientes em diálise peritoneal (DP) é associada à aterosclerose, causa de morte mais comum entre esses pacientes. Semelhantemente à síndrome nefrótica, supõe-se que a perda de proteínas conjuntamente a de fatores de regulação da hemostasia leva ao estímulo da síntese hepática de fatores pró-coagulantes, como o fibrinogênio, deslocando o equilíbrio hemostático em direção ao estado pró-trombótico. Pacientes em DP apresentam valores séricos elevados de marcadores da ativação endotelial e fatores pró-coagulantes, quando comparados a pacientes em hemodiálise (HD). A tromboelastografia (TEG) é um método que avalia propriedades do sangue global e dinâmica da coagulação, fornecendo, por meio de um traçado, valores absolutos do tempo de formação de fibrina (K), a agregação plaquetária (amplitude máxima - AM), a firmeza do coágulo (G), entre outros dados. Por final, classifica a coagulação em normal, hipocoagulante ou hipercoagulante segundo o índice de coagulação (IC) apresentado, sendo assim útil no diagnóstico precoce de coagulopatias. Por ser pouco utilizado em pacientes com DRC, utilizou-se o TEG na avaliação da hemostasia dos pacientes em diálise peritoneal automatizada (DPA) e investigou-se a relação com a perda de proteínas, bem como outras condições clínicas inerentes ao tratamento dialítico. MÉTODOS: este estudo foi do tipo transversal que incluiu pacientes estáveis em DPA. Foram obtidos dados demográficos, clínicos e bioquímicos de rotina do prontuário médico eletrônico. Adicionalmente, foram avaliados a coagulometria, a hemostasia primária [antitrombina (AT), proteína S, fator VIII (FVIII), fator IX (FIX), fator V (FV), fibrinogênio e dímero-D] e o TEG. Os pacientes foram submetidos ao teste de equilíbrio peritoneal (PET), a avaliação da perda de proteínas para a solução de diálise (PSD) e a absorção de glicose. O estado nutricional dos pacientes foi avaliado por meio de métodos objetivos e subjetivos. RESULTADOS: vinte pacientes (38±16 anos de idade, 55% mulheres, 22,4±14,8 meses em DPA, 40% de glomerulopatia, 70% transportadores médio lento/lento e em bom estado nutricional) foram incluídos no estudo. O FVIII e FIX elevados em 85% e 50% da amostra, respectivamente. O fibrinogênio (553,8±100,5 mg/dL) e o dímero-D (720 (520-1940) ug/L) foram elevados em mais da metade dos pacientes. O TEG revelou 55% dos pacientes hipercoagulantes, 45%, normais, e nenhum era hipocoagulante. Os pacientes hipercoagulantes foram caracterizados por um tempo K menor (1,3±0,4 vs. 1,8±0,3 minutos, p=0,007); AM (72,1±2,4 vs. 64,7±3,6 mm, p=0,000) e G (13,1±1,6 vs. 9,3±1,5 K, p= p=0,000) elevados, também alterados em 78% e 33%, respectivamente, nos pacientes com coagulação normal. Pacientes hipercoagulantes também apresentaram maiores valores de plaquetas (251±28 vs. 214±51 mil/mm³, p=0,038), que se correlacionou positivamente com AM/G (r=0,594, p=0,006), enquanto a proteína C foi menor (108±12 vs. 117±20 %, p=0,034) e a AT se correlacionou positivamente com o tempo K (r=0,635, p=0,011). Não houve diferença de albumina sérica, PSD, cinética de creatinina e estado nutricional entre os grupos normal e hipercoagulante. Os pacientes hipercoagulantes, entretanto, apresentaram menores valores de hemoglobina (10,3±1,4 g/dL vs. 12,0±1,1 g/dL; p=0,007), que se correlacionou negativamente com AM/G (r=-0,673, p=0,001), bem como o hematócrito (31±4 % vs. 36±3 %; p=0,010), que também se correlacionou negativamente com AM/G (r=-0,640; p=0,002). CONCLUSÃO: demonstramos que pacientes em DPA estáveis apresentaram uma tendência pró-trombótica caracterizada pela hiperfunção plaquetária e maior força de coágulo. Mesmo não havendo linearidade na relação com a hemostasia a perda de proteínas pode ter contribuído para a hipercoagulabilidade nesses pacientes. Entretanto, os eritrócitos reduzidos representaram um fator de confusão para o resultado do / INTRODUCTION: reduced serum albumin in patients on peritoneal dialysis (PD) is associated to atherosclerosis that is the leading cause of death. Similarly to nephrotic syndrome they lose protein; it is assumed that together with regulating factors of haemostasis this loss leads to liver synthesizes of procoagulants factors, such as fibrinogen, shifting the hemostatic equilibrium to a prothrombotic state. Patients on PD present elevated serum markers of endothelial activation and coagulant factors when compared with hemodialysis (HD) patients. Thromboelastography (TEG) is a method that evaluate blood properties through coagulation\'s global and dynamic perspectives, providing through a trace absolute values of fibrin\'s time formation (K), platelet aggregation (maximum amplitude - MA), clot strength (G), among other data. Finally it classifies the coagulation in normal, hypocoagulant or hypercoagulant according to the coagulation index (CI), so that it is useful in the early diagnosis of coagulopathies. TEG is not often used in patients with CKD, because of this we chose to use TEG for hemostatic evaluation in patients on APD and investigated its relation with protein loss as well as other clinical conditions intrinsic to the dialytic therapy. METHODS: this was a cross-sectional study that included stable patients on automated peritoneal dialysis (APD). Demographic, clinical and routine biochemical data were obtained from electronic medical chart. Additionally the coagulometry, primary hemostasis [antithrombin (AT), protein S, factor VIII (FVIII), factor IX (FIX), factor V (FV), fibrinogen and D-dimer] and TEG were evaluated. Patients were submitted to peritoneal equilibrium test (PET), protein loss to dialysis solution (PDS) and glucose absorption evaluations. Patients nutritional status was evaluated by objective and subjective methods. RESULTS: twenty patients (38±16 years old, 55% women, 22.4±14.8 months on APD, 40% of glomerulopathy, 70% slow average/slow transporters and well nourished) were included in this study. FVIII and FIX were elevated in 85% and 50% of the sample, respectively. Fibrinogen (553.8±100.5 mg/dL) and D-dimer (720 (520-1940) ug/L) were elevated in over half of the patients. TEG showed 55% of the patients hypercoagulant, 45% were normal and nobody was hypocoagulant. Hypercoagulant patients were characterized by a lower K-time (1.3±0.4 vs. 1.8±0.3 minutes; p=0.007); elevated MA (72.1±2.4 vs. 64.7±3.6 mm; p=0.000) and G (13.1±1.6 vs. 9.3±1.5 K; p= p=0.000); altered too in 78% and 33%, respectively, in normal coagulation patients. Hypercoagulant patients presented too higher values of platelet count (251±28 vs. 214±51 mil/mm³, p=0,038), but within the normal range, that correlated positively with MA/G (r=0.594; p=0.006) while protein C was lower (108±12 vs. 117±20 %; p=0,034) and AT correlated positively with K-time (r=0.635; p=0.011). There was no difference to serum albumin, PDS, creatinin kinetic and nutritional status between hypercoagulant and normal groups. However hypercoagulant patients presented lower values of hemoglobin (10.3±1.4 g/dL vs. 12.0±1.1 g/dL; p=0.007); that correlated negatively with MA/G (r=-0.673; p=0.001), as well as hematocrit (31±4 % vs. 36±3 %; p=0,010), which also correlated negatively with MA/G (r=-0.640; p=0.002). CONCLUSION: we demonstrated that stable patients on APD presented a prothrombotic tendency characterized by platelet hyperfuntion and clot strength. Even though there was no linearity in relation to hemostasis; protein loss may have contributed to the hypercoagulability in these patients. However reduced erythrocytes were a confounding factor in the TEG analysis

La matière organique dissoute (MOD) est un composant important des eaux naturelles, déterminant la forme des éléments et les émissions de gaz à effet de serre (CO2, CH4), et influence la biodiversité des milieux des eaux. Les eaux boréales sont connues pour être généralement riches en fer, et cela est vrai en particulier pour les eaux de la région étudiée (Carélie du Nord, Russie). Le fer est associée aux MOD dans les complexes de bas poids moléculaire et les colloïdes organo-ferreux de haut poids moléculaire, qui agissent comme les principaux transporteurs d'éléments traces métalliques dans le continuum hydrologique typiques de cette région : sol - marais - rivière - lac. La transformation des colloïdes organo-ferreux se fait sous l'influence de deux facteurs principaux: la dégradation bactérienne et la dégradation photochimique. Cette étude est consacrée à l'analyse du comportement du carbone organique dissous (COD) et des éléments traces (ET) des eaux de surface en zone boréale sous l'influence de l'activité métabolique des bactéries hétérotrophes et de l'oxydation photolytique des MOD sous l'effet de la lumière du soleil. Dans les expériences, un lixiviat de tourbière, un échantillon d'eau de marais, un échantillons d'eau de ruisseaux, un échantillon de rivière, un échantillon d'eau de lac humique, un échantillon d'eau de lac oligotrophique et un pluvio-lessivat collecté sous un pin, échantillons dans lesquelles dominent les MOD de nature humique, ont été utilisés comme substrats. Des expériences en laboratoire utilisant des communautés monosouches de bactéries aérobies hétérotrophes Pseudomonas aureofaciens et Pseudomonas saponiphila (prélevées sur le territoire de Carélie) ont permis d'établir que la MOD allochtone des milieux aquatiques en zone boréale possède une forte résistance à l'activité des bactéries étudiées. Le taux de minéralisation bactérienne du COD était de 0 à 4.3 mgC.L-1.jour-1 selon le substrat, et la fraction de faible poids moléculaire (<1 kDa) de la MOD est plus susceptible de destruction que celle de poids moléculaire élevé (de 1 kDa à 0.22 µm). L'interaction des bactéries avec divers substrats aqueux a montré pour une large gamme d'éléments (Al, Fe, Mn, Ni, Co, Cu, Cd, REE, U) une prédominance significative d'une adsorption rapide sur la surface cellulaire observée lors de la première heure d'expérience (t < 1h) par rapport à une diminution lente observée lors de la suite de l'expérience (1h < t < 96h), diminution lente lié à l'assimilation intracellulaire des métaux et à la coprécipitation extracellulaire des éléments avec des hydroxydes de Fe et Al. L'analyse de divers substrats a montré une augmentation de l'adsorption des métaux avec le rapport DOC/Fe dans la solution initiale, ce qui peut être due à la compétition entre Fe et d'autres cations métalliques pour les sites d'adsorption anioniques des surfaces des cellules bactériennes. Le suivi des dynamiques d'élimination des métaux des solutions expérimentales pendant 96 heures n'a pas mis en évidence de lien entre l'élimination des métaux et le pH et les valeurs absolues de concentration de DOC et de Fe. Une relation a été établie entre la diminution lente (96 h) des éléments et le degré initial de sursaturation de la solution en oxydes et hydroxydes de fer et d'aluminium. Des expériences en conditions naturelles avec des échantillons d'eau de rivière et de marais a montré que la destruction photolytique de la MOD est beaucoup plus efficace pour l'eau de marais. / Dissolved organic matter (DOM) is an important component of natural waters, determining the form of elements and the emission of greenhouse gases (CO2, CH4), as well as affecting water biodiversity. A feature of boreal waters, and in particular the study area waters (North. Karelia, Russia), is high concentration of Fe (III), associated with DOM in low-molecular complexes and in high-molecular organo-ferric colloids, which act as the main carriers of metallic trace elements in the most typical hydrological continuum soil - bog - river - lake. The transformation of organo-ferric colloids occurs under the influence of two main factors: bacterial and photochemical degradation. The present study is devoted to the analysis of dissolved organic carbon (DOC) and trace elements (TE) behavior in surface waters of the boreal zone under the influence of the heterotrophic bacteria metabolic activity and photolytic oxidation of DOM under sunlight exposure. For the purpose of experiments there were used substrates with predominate allochthonous DOM of humic nature, including peat leachate, pine crown throughfall, fen, humic lake, stream, river and oligotrophic lake. An experiment carried out in laboratory conditions using monocultures of heterotrophic aerobic bacteria Pseudomonas aureofaciens and Pseudomonas saponiphila (isolated on the territory of Karelia) allowed to establish that allochthonous DOM of the boreal zone reservoirs possesses high resistance to the activity of the explored bacteria. The rate of bacterial mineralization of DOC was observed in range from 0 to 4.3 mgC L-1day-1, depending on the substrate, and the low molecular weight fraction (<1 kDa) of DOM was found to be more prone to destruction than high molecular weight (from 1 kDa to 0.22 µm). The interaction of bacteria with various aqueous substrates showed a significant predominance of short-term (< 1 h) adsorption on the cell surface for a wide range of elements (Al, Fe, Mn, Ni, Co, Cu, Cd, REE, U) over a long term (1 h - 96 h) intracellular uptake of metals and extracellular coprecipitation of elements with Fe and Al hydroxides. Among different substrates, there was an increase in the adsorption with the increase of DOC/Fe ratio in solution, which can be linked to a competition between Fe and metal cations for anionic adsorption sites on cell surface. The long-term removal of dissolved metals did not show any link to pH, DOC, and Fe concentration.

De nombreuses études soulignent une relation directe entre la prévalence de la fibrillation auriculaire (FA) et le vieillissement. La senescence cellulaire et le phénotype sécrétoire associé semblent jouer un rôle central dans le développement de l'inflammation auriculaire. Cette inflammation est à l’origine d’un remodelage auriculaire délétère (stress oxydant, fibrose) favorable à la perpétuation et au maintien de la FA. Par ailleurs, il est connu que la FA favorise la coagulation locale et systémique. Cependant, l'impact des facteurs de la coagulation, notamment la thrombine, sur la FA est peu connu. L’objectif de cette étude était de déterminer le lien entre la sénescence des cellules endothéliales atriales et le phénotype pro-inflammatoire et pro-adhésif, la fibrose et le remodelage auriculaire tout en évaluant l’impact de la coagulation, et en particulier le rôle de la thrombine. / Many studies documented strong relationship between ageing and development of atrial fibrillation (AF). Moreover, it has been found that senescence and senescence-associated- secretory-phenotype play an important role in development of overall atrial inflammation which can ultimately ends up in atrial structural remodeling paving the way to AF perpetuation and maintenance. Moreover, it has been known for decades that AF has been associated with the activation of local and circulating coagulation factors. However, little is known about the impact of coagulation-derived factors, in particular thrombin, on the onset of AF. The aim of the present study was to determine the link between atrial endothelial cells (AECs) senescence and the induction of pro-inflammatory, pro-adhesive, pro-fibrotic and pro-remodelling AECs patterns and also to evaluate the contribution of coagulation derived-factors such as thrombin.

Cette étude avait comme objectif d’évaluer la coagulation par l’utilisation de la thrombélastographie (TEG®) et de la génération de thrombine (GT) chez des beagles en santé recevant de la prednisone ainsi que chez des chiens atteints d’hyperadrénocorticisme (HAC). Dans un premier temps, six beagles adultes en santé ont été évalués dans une étude prospective longitudinale au courant de laquelle chaque individu recevait 1 mg/kg/jour de prednisone par la voie orale pendant 2 semaines. Après un arrêt de traitement d’une durée de 6 semaines, ils ont finalement reçu 4 mg/kg/jour de prednisone pour encore 2 semaines. Les tracés TEG® et les mesures de la GT ont été obtenus au temps 0, à la fin des 6 semaines d’interruption de traitement, ainsi qu’à la suite des 2 dosages de prednisone. Suite aux 2 traitements avec la prednisone, des résultats significatifs,lorsque comparés aux valeurs de base, ont été obtenus pour la cinétique du caillot (« clot kinetics » ou K), l’angle alpha (α) et l’amplitude maximale (« maximal amplitude » ou MA). La GT avait augmenté de manière significative mais seulement après la dose de 1 mg/kg/jour de prednisone. Dans un deuxième temps, 16 chiens atteints d’HAC ont été évalués avant l’initiation d’un traitement pour leur condition. Quinze chiens ont été évalués par TEG® et 15 par GT. Les données obtenues ont ensuite été comparées aux valeurs normales. L’analyse par TEG® a démontré que 12/15 chiens avaient au moins un paramètre suggérant un état d’hypercoagulabilité. L’analyse par GT a démontré que 4/15 chiens avaient des changements compatibles avec un état d’hypercoagulabilité. Un test t-pairé pour des valeurs de variance inégales a démontré que le groupe de chiens atteints d’HAC avait des tracés hypercoagulables et un potentiel endogène de thrombine (« endogenous thrombin potential » ou ETP) plus élevé, lorsque comparé à la population de référence. / The purpose of this study was to use thrombelastography (TEG®) and thrombin generation (TG) to evaluate coagulation in healthy beagles receiving oral prednisone as well as client-owned dogs diagnosed with hyperadrenocorticism (HAC).Six healthy adult beagles were used in a prospective ongitudinal study whereby all dogs received 1 mg/kg of prednisone orally once daily for two weeks, followed by a 6-week washout period and then 4 mg/kg of prednisone orally once daily for two weeks. TEG® tracings and TG measurements were obtained at baseline, at the end of the washout period and at the end of both corticosteroid trials. Significant results as compared to baseline were obtained for clot kinetics (K), alpha angle (α)and maximum amplitude (MA), with tracings compatible with a hypercoagulable profile following both corticosteroid trials. Thrombin generation resulted in a significant increase in endogenous thrombin potential (ETP) after the 1 mg/kg/day trial only. Secondly, sixteen dogs affected by HAC were evaluated. Fifteen dogs were evaluated by TEG® and 15 dogs were evaluated by TG before treatment and compared to the normal reference values. For the TEG® analysis, 12/15 dogs had at least one parameter that suggested hypercoagulability. A paired t test for values with unequal variance was used to compare the HAC dogs to the healthy dogs and found that HAC dogs have hypercoagulable TEG® tracings. The same results were found when TG was used with the ETP elevated in the HAC dogs. However, when dogs were evaluated individually, only 4/15 had hypercoagulable TG results.

The aim of this study was to investigate the impact of the casein microstructure on the molecular diffusion of probes with different sizes and deformabilities. The mobility of molecular flexible ('PEG') and rigid (dendrimer) probes of various sizes was studied in suspensions and gels of NPC and SC at various protein concentrations. Measurements were carried out by NMR, which makes it possible to probe translational mobilities over a distance of 1.5 microns, as well as local mobilities at the molecular scale (several nanometers) through the relaxation times, T2. A coherent model was used and the same mechanism was proposed to describe the diffusion of small probes in both casein dispersions. It is the combination of different factors that should be considered: the ratio of the probe size to the distance between the obstructing particles or the entanglement points, as well as the flexibility of the probe. The rotational diffusion of PEG and dendrimer probes was less hindered than translational diffusion in both casein systems. Different relaxation behaviors were observed between the two casein systems and retardation in T2 relaxation times was highlighted in rennet and acid casein gels. These results are probably related to the local mobility of the matrix. The overall results of this project led to a better understanding of probe mobility in casein systems and made it possible to propose a new model that challenges the previous one proposed by Le Feunteun et al. to describe the diffusion of probes in casein systems.