Neste estudo, testamos a hipótese de que a estimulação colnérgica pela administração de piridostigmina, um agente anticolinesterásico reversível, protege o miocárdio submetido à isquemia miocárdica crônica durante 3 tempos de observação: 7, 21 e 42 dias. Para essa avaliação foram medidos a área de acinesia (índicador de área de infarto), os índíces das funções sistólica e diastólica pela ecocardiografia e por medida direta bem como marcadores da função autonômica como a sensibilidade do barorreflexo e a variabilidade da frequência cardíaca (FC) e da pressão arterial (PA). O bloqueio farmacológico do sistema nervoso autônomo e o estudo da via eferente parassimpática foram também realizados. Utilizou-se ratos Wistar machos divididos em 4 grupos: controle, controle piridostigmina, infartado e infartado piridostigmina. Os resultados mostraram os efeitos protetores da piridostigmina nos diferentes tempo de infarto com redução da área de acinesia ( maior que 80%) tanto pelo ecocardiograma quanto pela histologia. Além disso observou-se recuperação das funções sistólica e diastólica, com normalização da pressão diastólica final e das derivadas de contração e relaxamento. Essas melhoras foram mais consistentes em 21 e 42 dias, sem diferenças entre esses tempos de tratamento. Em 7 dias ainda persistiram alguns índices de disfunção ventricular, embora a função autonômica estivesse bem preservada. Parte dessa melhora se deve, provavelmente, ao aumento do tônus vagal e redução do simpático. A potenciação da bradicardia pela estimulação elétrica do vago induzida pela piridostigmina confirma seu papel com estimulador colinérgico. A sensibilidade do barorreflexo reduzida de forma semelhante pelo infarto do miocárdio aos 7, 21 e 42 dias, voltou aos valores controle após o tratamento com piridostigmina, sem diferenças devidas ao tempo de tratamento. Da mesma forma, a variabilidade da FC foi aumentada após o tratamento com o brometo de piridostigmina no grupo infartado o que também ocorreu no grupo controle. Em adição, o aumento da banda de alta frequência e a redução da banda de baixa frequência que refletem respectivamente a modulação parassimpática e simpática da variabilidade da frequência cardíaca, levaram a uma redução no balanço simpato-vagal dos animais infartados tratados. Em conclusão, a estimulação colinérgica por piridostigmina preserva a função parassimpática protegendo o miocárdio da isquemia induzida por oclusão coronariana, mantendo a função cardíaca e a função autonômica dentro dos valores da normalidade / In this study we tested the hypothesis that cholinergic stimulation by pyridostigmine administration, a reversible cholinergic inhibitor, protects the ischemic myocardial in three periods of follow-up: 7, 21 and 42 days. For this evaluation we measured the akinetic area (infacrtion area indicator), systolic and diastolic indexes by echocardiography and left ventricle direct measurements as well as autonomic function markers, as baroreflex sensitivity and heart rate (HR) and blood pressure (BP) variabilities. Pharmacological blockade of the autonomic nervous system and the study of the efferent parasympathetic pathway were also performed. Male Wistar rats were divided in 4 groups: control, control treated with pyridostigmine, infarcted and infarcted treated with pyridostigmine. The results showed the protective effects of pyridostigmine in the different periods of infarction, with the reduction of the akinetic area (more than 80%), either by the echocardiography and by histology. Moreover, we observed systolic and diastolic functions recovery, with normalization of the end diastolic pressure and the maximum rates of left ventricle BP rise and fall. These improvements were more consistent in 21 and 42 days, with no differences between these two periods of treatment. In 7-day treatment, some indexes of ventricular dysfunction remained, although the autonomic function seemed to be preserved. Part of these improvements is probably due to the increase in the vagal tonus and the decrease in the sympathetic tonus. The pyridostigmine effects in the potencialization of the bradycardia induced by vagus nerve electrical stimulation confirms its role as a cholinergic stimulator. The reduced baroreflex sensitivity by myocardial infarction, which was similar in 7, 21 and 42 days, returned to control values after pyridostigmine treatment, without differences related to treatment extent. Similarly, HR variability was increased after pyridostigmine treatment in the infarcted group, which also occurred in the control group. In addition, the increase in the high frequency band and the reduction in the low frequency band, which reflect, respectively, the parasympathetic and the sympathetic modulation of HR variability, led to the diminishment in the sympatho-vagal balance in the infarcted-treated animals. In conclusion, cholinergic stimulation by pyridostigmine preserves parasympathetic function, protecting the myocardial against the ischemia induced by coronary occlusion, maintaning cardiac and autonomic functions within normal values

La climatisation par absorption est un système de production de froid tritherme énergétiquement intéressant. La compression mécanique intervenant au sein des systèmes classiques à compression de vapeur (premier poste de consommation énergétique) est remplacée par une compression dite thermochimique nécessitant un apport de chaleur important. Dans le cas d'une application automobile il est possible de faire fonctionner le système grâce aux pertes thermiques du moteur. La climatisation par absorption est à l'étude au sein du service R&D du fabricant d'automobiles PSA Peugeot Citroën depuis une décennie. L'innovation majeure de PSA concerne l’évaporateur/absorbeur : un nouveau système basé sur le confinement du réfrigérant et de la solution absorbante à l'intérieur de structures capillaires a été breveté. Ce nouveau système a pour but d'éviter le mélange intempestif des fluides. L'analyse expérimentale de cet évaporateur/absorbeur a montré que la puissance frigorifique est limitée par le phénomène d'absorption. Il a été prouvé que l'effet frigorifique produit par le système est égal à un tiers de l'effet maximal qui pourrait théoriquement être réalisé. Un modèle simple de la zone d'absorption est proposé, il fournit une ligne directrice pour améliorer la conception du composant. Une revue de la littérature a montré que les modèles d'absorption sont basés sur des hypothèses dont la fiabilité n'est pas évidente. Aussi, la plupart des auteurs considèrent que les propriétés thermophysiques sont constantes. Cette hypothèse a été étudiée dans le cas simple de l'absorption statique. La modélisation des transferts simultanés de chaleur et de masse au sein de la solution absorbante nécessite de prendre en compte l'augmentation de volume de cette dernière. Les équations régissant les transferts ont été résolues par la méthode des volumes finis, sur un maillage dynamique. Deux procédures pour la déformation du maillage ont été mises en oeuvre et comparées. Les résultats numériques ont été comparés aux résultats expérimentaux obtenus sur un banc développé dans le cadre de ce travail et aux données expérimentales issues de la littérature. Enfin, l'impact des gaz incondensables sur le taux d'absorption a été étudié numériquement et expérimentalement, dans le cas de l'absorption statique. Cette étude a permis de confirmer les phénomènes à l'origine de la diminution du taux d'absorption. Cependant, l'effet de la gravité sur l'impact des gaz incondensables n'a pas pu être clarifié avec certitude. / Automotive air conditioning systems are based on the vapour compression cycle that requires mechanical energy for its operation. This mechanical energy is provided by the engine, which engenders year-averaged fuel extra consumptions, and thereby extra pollutant emissions, of the order of 5 %. Absorption cooling technology is of interest as this system could be driven by the engine waste heat.The absorption air conditioning technology has been under the scope of the R&D services of the french manufacturer PSA Peugeot Citroën for a decade. PSA's major innovation concerns the evaporator/absorber: a new system based on the confinement inside capillary structures of refrigerant and absorbent falling films has been patented. This new layout aims at avoiding unwanted mixing of the fluids. Experimental analysis of this original component has shown that the refrigerating effect is limited by the absorption phenomenon. It was proved that the refrigerating effect produced by the system is equal to one third of the maximal effect that could be achieved. A simple model of the absorption part has been proposed. It provides a guideline to improve the design of the component. A literature review has revealed that the absorption models are based on assumptions whose reliability is not obvious. Especially, most of the authors assume that the thermophysical properties are constant. The impact of this assumption has been clarified in the simple case of pool absorption. Modeling the simultaneous heat and mass transfer that takes place in the liquid absorbent requires to account for the increase of the liquid volume. This was achieved by means of a finite-volume treatment of the governing equations over a dynamic grid. Two procedures for the grid deformation have been implemented and compared. The numerical results have been compared to experimental results obtained on a bench developed on purpose and to experimental data from the literature. Finally, the impact of the non-absorbable gases on the absorption rate has been investigated numerically and experimentally, in the pool absorption case. This study enabled to confirm the phenomena at the origin of the decrease of the absorption rate. However, we could not clarify with certainty the importance of gravity-driven flows in the vapour phase, in the presence of non-absorbable gases.

La climatisation automobile est un enjeu majeur pour les constructeurs automobiles dans la mesure où elle occasionne un rejet de 10 g de CO2 par km, une surconsommation énergétique de près de 5 % et sera pris en compte dans le bilan MEVG à l'horizon 2020. Dans cette perspective, le constructeur automobile PSA Peugeot Citroën a développé un nouveau procédé : la climatisation par absorption de vapeur d'eau par une solution saline de bromure de lithium, qui marque la rupture avec le système classique à compression de vapeur. Le travail mené dans ce manuscrit s'est focalisé au niveau de l'organe principal du système, l'évaporateur/absorbeur où les deux fluides s'écoulent et sont confinés chacun entre deux grilles tissées par des effets capillaires. Les transferts de masse et de chaleur qui s'y produisent, ont lieu à l'interface liquide/vapeur formée par des ménisques de forme complexe qui constituent la surface de d'échange. L'objectif est d'intensifier les transferts de masse et de chaleur qui diffuse à travers l'interface. Un banc expérimental permettant la description tridimensionnelle de la forme des ménisques au moyen de la microscopie confocale a été développé. Le modèle « volume of fluid » a été utilisé pour la reconstruction numérique de l'interface liquide/ vapeur. La comparaison entre les données expérimentales et les simulations numériques a montré un bon accord. Ces simulations montrent que l'écoulement est influencé par la grille avec la création de zones mortes et des mouvements de vorticité. Une optimisation numérique a été menée avec comme fonction objectif le flux qui diffuse à travers l'interface. Celle-ci a permis de définir des paramètres optimales de la grille permettant d’atteindre un flux de chaleur de près de 2,5 fois supérieur à celui du cas de référence. Cette optimisation a permis l'identification d'une zone préférentielle dans laquelle les transferts de chaleur sont maxima. Le travail a aussi abordé l'influence de la forme des fils et de la forme des ménisques, montrant qu'il est préférable d’adopter des matériaux à caractère hydrophobe avec des fils à section circulaire. / Abstract The automotive air conditioning is a major challenge for the automotive manufacturers insofar it causes a release of 10 g/CO2/km, engenders an extrafuel consumption of 5 % and will be taken into account in the balance sheet in 2020 MEVG. In this perspective, the automotives constructor PSA Peugeot Citroën has developed a new process, absorption air conditioning of water vapor by lithium bromide solution, which marks a break with the classic vapor-compression system. This manuscript is focused at the main body of the system, an innovative evaporator/absorber where both fluids are flowing down and confined between two finely meshed plastic wire screens and maintained between them by capillary effects. The heat and mass transfers in this system occur at the liquid/vapour interface formed by complex menisci that represent the surface of transfer. An experimental test bench allowing the description of three-dimensional shape of menisci using confocal microscopy has been carried. The volume of fluid model has been used for the numerical reconstruction of the liquid/vapour interface. The comparison between numerical and experimental data has shown a good agreement. Numerical simulations have shown that the flow is influenced by the geometry that promotes the creation of stagnant layer solution and vorticity zones. A numerical optimization has been carried with as objective function the heat rate that di uses through the interface. This one has allowed to get out the optimal parameters allowing to have an heat rate of more than 2.5 times higher compared to the reference case. This optimization has highlighted a preferential zone in which heat transfers are maximum. The work has also dealt with the e ect of the shape of the wires and the effect of the shape of menisci on the transfer, showing that it is preferable to work with hydrophobic materials and with cylindrical wires.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work describes our results on the use of indium(I) bromide in Organic Synthesis, namely the reaction mechanisms and stereochemical outcome. Indium enolates, generated from the reaction between indium(I) bromide and α,α-dichloroketones, react with carbonyl compounds. The primary coupling with aldehydes leads to the diastereoselective synthesis of (syn+anti)-2-chloro-3-hydroxypropan- 1-ones, which can be converted to the respective trans-epoxyketones, exclusively. The indium(III) alkoxides of the 2-chloro-3-hydroxy-propan-1-ones are transformed into their (E)-prop-2-en-1-ones derivatives upon reaction with InBr according to a sequenced reaction mechanism. The most relevant feature of these reactions is that although the primary coupling with aldehydes affords a mixture of the two diastereoisomers of the indium(III) alkoxides, both the trans-epoxyketones and the E-enones were produced with rigorous stereoselectivity. These results are understood in terms of the enolate geometry (E or Z) and the retro-aldol reaction (kinetic/thermodynamic control) relating both forms of the enolate. / Este trabalho descreve os resultados dos estudos realizados sobre aplicações de brometo de índio(I) em Síntese Orgânica. Especificamente os aspectos pertinentes aos mecanismos reacionais e estereoquímicos. A reação entre brometo de índio(I) e α,α-diclorocetonas produz, in situ, enolatos de índio que reagem com compostos carbonílicos. O acoplamento com aldeídos leva à formação diastereosseletiva de (syn+anti)-2-cloro-3-hidroxi-propan-1-onas, que podem ser convertidas às respectivas oxiranas, exclusivamente trans. O aldolato de índio dos compostos 2-cloro-3-hidroxi-propan-1-onas é transformado, pela ação de um equivalente extra de InBr, nos respectivos derivados (E)-prop-2-en-1-onas, segundo um mecanismo de reações seqüenciais. Embora o acoplamento primário com aldeídos leve a uma mistura diastereoisomérica dos aldolatos de índio, as transoxiranas e as E-enonas são produzidas com rigorosa estereosseletividade. Estas são as características mais relevantes e podem ser compreendidas em termos da geometria do enolato (E ou Z) e do equilíbrio retro-aldol (controle cinético ou termodinâmico) entre as duas formas do enolato.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Light and ultraestructural changes of central and peripheral nervous system lesions in mice KO for connexin-32 and submitted to the ethidium bromide gliotoxic demyelinating model are described. Their KO condition was tested with PCR and a negative connexin-32 labelling was performed by immunofluorescence. The experimental animals were C57BL/6 normal mice and C57BL/6 KO for connexin-32. For all groups the animals were maintained in cages of 5 individuals within a temperature controlled room and had ration and filtered water ad libitum. A single local injection of either 0,1% ethidium bromide in normal saline (5 μl in the brainstem and 1 μl in the sciatic nerve) or normal saline was performed as described for Wistar rats. The injected mice were observed daily until euthanasia was performed at 24, 48 hours and 3, 7, 15, 21 and 30 days after injection. The mice were perfused through the heart with either neutral 10% formalin or 2,5% glutaraldehyde. Histochemical, immunohistochemical, immunofluorescence and transmission electron microscopic methods were used to analyze the development of the lesions after differentiated processing. Hematoxylin- eosine, luxol fast blue and toluidine blue methods and immunolabelling with anti-GFAP, anti-CNPase, anti-S100 protein and anti-OSP, anti Cx32 and anti Cx43 antibodies were used. Within the CNS the lesions showed an acute degenerative phase with disappearance of glial cells, and myelin sheaths were withdrawn by a scant number of macrophages. In KO mice some granulocytes were detected within the lesions in tight contact with decaying myelin sheaths. Remyelination was carried out by oligodendrocytes since no Schwann cells were seen during the regenerating process of KO mice. Occasional remyelinating Scwann cells were seen in normal mice. For the sciatic nerves, Schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compaction and redundant loops (tomacula) were conspicuous. Mast cells degranulated or not were seen in all BE- induced lesions and after saline injection. It is concluded that the repair of the CNS demyelinated lesions differs from the observed in normal and immunosupressed rats because Schwann cells remyelination was absent; the absence of connexin-32 may have caused that absence. The regeneration of lost myelin sheaths within the PNS followed the pattern already reported for this model in other species. It is suggested that the absence of connexin-32 determined the different repair of the myelin sheaths within the CNS whereas for the PNS, the normal pattern of tissue response might be due to the early age of the injected mice. / São descritas as alterações de microscopia de luz e ultra-estruturais induzidas pelo brometo de etídio no sistema nervoso central e periférico de camundongos KO para conexina 32. O genótipo KO foi testado por PCR e confirmado por imunofluorescência negativa para conexina 32. Os animais dos experimentos foram camundongos C57BL-6 normais (controles) e KO para conexina 32. Todos os camundongos foram mantidos em gaiolas de 5 indivíduos em sala climatizada e receberam ração e água à vontade. Uma única injeção de BE 0,1% em salina 0,9% ou de salina 0,9% (5 μl na cisterna basal e 1μl no nervo ciático) foi realizada como descrita em ratos Wistar. Os camundongos eram observados diariamente até ser realizada a eutanásia às 24 e 48 h, 3, 7, 15, 21 e 30 dias após a injeção. Os camundongos foram perfundidos através do coração; um grupo com glutaraldeído 2,5% visando o processamento para microscopia eletrônica; um outro grupo com solução salina com EDTA e posterior fixação em metacarn para inclusão em parafina. As amostras incluídas em parafina foram analisadas através dos métodos de hematoxilina e eosina, luxol fast blue e azul de toluidina. Foram realizadas imunoistoquímica e imunofluorescência visando a marcação de GFAP, CNPase, OSP, S100, e Cx43 e Cx32, respectivamente. As lesões do SNC eram discretas e tiveram uma fase ativa com desaparecimento das células gliais; os debris celulares e de mielina foram retirados por um reduzido número de fagócitos. Nos camundongos KO foram vistos granulócitos em estreito contato com bainhas de mielina em degradação. A remielinização dos axônios desmielinizados foi realizada exclusivamente por oligodendrócitos nos camundongos KO; nos camundongos normais, ocasionais células de Schwann podiam ser encontradas remielinizando axônios do SNC. No nervo ciático, as células de Schwann intoxicadas rejeitaram seus internodos de mielina; após sete dias, finas bainhas reparadas eram encontradas, com compactação irregular da mielina e alças redundantes (tomacula). Mastócitos, desgranulados ou não, eram vistos nas lesões do BE e após a injeção de solução salina. Conclui-se que o reparo das lesões do SNC difere do observado em ratos normais e imunossuprimidos devido à ausência de remielinização por células de Schwann; a falta de expressão da Cx 32 e o tamanho reduzido das lesões podem ter contribuído para essa ausência. A regeneração das bainhas perdidas no SNP obedeceu ao padrão descrito para esse modelo em outras espécies. Sugere-se que a ausência da Cx 32 não afetou o reparo do SNP devido à idade precoce dos animais.

Cette étude a pour objectif d’étudier expérimentalement les interactions entre différents anions (chlorure, bromure, nitrate et sulfate) et le silicate de calcium hydraté (C-S-H) afin de construire un modèle thermodynamique capable de prédire cette interaction. Des suspensions de C-S-H synthétisées ont été mises en contact avec différents types de sel (sel de calcium ou d’alcalins). L’influence de la température et de l’incorporation d’aluminium au sein de la structure du C-S-H ont également été prises en compte.L’utilisation d’une méthode d’analyse classique de ce type de système (c’est-à-dire séparation des phases liquide et solide puis analyse de la solution) a révélé ses limites avec, entre autres, une mauvaise reproductibilité des résultats. L’étape de séparation des phases s’est trouvée être à l’origine des difficultés rencontrées.Une seconde méthode d’analyse ne nécessitant pas de filtration des suspensions de C-S-H a été mise au point pour cette étude.Les résultats obtenus ont alors démontrés la non-adsorption des chlorures, nitrates ou bromures par les particules de C-S-H : ces anions n’ont qu’un rôle de compensation de charge au sein de la couche diffuse entourant les particules en suspensions.Les ions calcium (dans le cas d’ajout de sel de calcium) ne s’adsorbent que très faiblement à la surface du C-S-H. Ceci n’est pas influencé par la présence d’aluminium dans la structure. Une température plus faible (5°C) ou plus élevée (40°C) conduit à une adsorption plus faible, voire nulle.L’utilisation d’un modèle thermodynamique de simulation de C-S-H (développé dans une autre étude) a permis de reproduire les résultats expérimentaux obtenus, confirmant donc la validité de ces derniers mais également celle du modèle utilisé. / This project aims to study the interactions between calcium silicate hydrate (C-S-H) and different anions (chlorides, bromides, nitrates and sulfates) in order to build a thermodynamic model and then be predictable. The simplified system CaO-SiO2-H2O is studied by synthesizing C-S-H suspensions and mixing them with different kind of salts (calcium salt or alkali salt). The influence of the temperature and the presence of aluminum in the structure of the C-S-H is also examined.A classical way to investigate this kind of system is to separate the liquid phase from the solid phase in order to analyze them separately. Nevertheless, this step has a large influence on the system, and the experimental results suffer from a really bad reproducibility.Another analysis method has then been developed in order to avoid the separation of the different phases. The results show that there is no adsorption of chlorides, bromides or nitrate on the surface of the C-S-H. They only have a role as a charge compensator in the diffuse layer around the particles in suspension.The calcium cation (in the case of calcium salt addition) can be adsorbed by C-S-H, but in a small quantity. The substitution of silicon by aluminum in C-S-H doesn’t have any influence on this phenomenon. A higher or lower temperature results in a weaker adsorption, even inexistent.Those experimental results have been reproduced by using a thermodynamic model developed in a previous study. Thus, the validity of the experimental part but also the one of the model are confirmed.

Formação, estabilidade coloidal e atividade in vitro contra Candida albicans dos arranjos supramoleculares compostos por drogas, lípides catiônicos e/ ou polieletrólitos foram sistematicamente avaliados através de espalhamento de luz dinâmico para tamanho de partículas, análise de potencial-zeta, espectrofotometria UV-visível, efeitos de droga sobre a transição de fase gel para líquido-cristalina da bicamada catiônica e quantificação de incorporação de droga nos diferentes sistemas. Arranjos supramoleculares de drogas antifúngicas como miconazol ou anfotericina B foram obtidos por solubilização das drogas em fragmentos de bicamada catiônica de brometo de dioctadecildimetilamônio ou como partículas de droga recobertas com uma camada do mesmo lípide catiônico. Como modelo de droga anticancerígena, a cisplatina foi incorporada com sucesso em polieletrólitos de carga oposta: quitosana e carboximetilcelulose. Cisplatina induziu substancial estabilização coloidal e redução de tamanho de partículas de carboximetilcelulose-quitosana, possivelmente atuando como agente de ligação cruzada entre os dois polieletrólitos. Assim também, arranjos supramoleculares de anfotericina B em baixa e em alta proporção molar droga: lípide catiônico foram revestidos com polieletrólitos como carboximetilcelulose, cloreto de poli(dimetildialilamônio) e polilisina formando nanopartículas catiônicas. Nanopartículas catiônicas de anfotericina B apresentaram estabilidade coloidal e atividade fungicida ótima. Quanto aos arranjos do miconazol com os fragmentos de bicamada catiônica, observou-se o mesmo com a vantagem de se obter ação sinérgica entre o lípide catiônico e a droga. Dois sítios de interação com fragmentos de bicamada catiônica foram identificados para o miconazol: (1) as bordas hidrofóbicas disponíveis à temperatura ambiente; (2) os sítios no seio da bicamada ocupados com o aumento de temperatura. A potente ação antimicrobiana do lípide catiônico brometo de dioctadecildimetilamônio (DODAB) per se, motivou um estudo sistemático da ação antimicrobiana comparada de DODAB e brometo de cetiltrimetilamônio (CTAB) contra Candida albicans. A adsorção destes compostos e seus agregados sobre a célula diminuiu seguindo a ordem: CTAB > fragmentos de bicamada de DODAB > vesículas grandes de DODAB. A ausência de vazamento de compostos fosforilados intracelulares de baixo peso molecular, DNA ou proteína em presença dos catiônicos evidenciou mecanismo de ação antimicrobiana independente de lise celular. A adsorção dos compostos catiônicos sobre células de Candida albicans mudou o sinal de potencial da superfície celular de negativo para positivo, exibindo uma relação clara entre a carga positiva sobre a célula e morte celular. / The formation, colloid stability and activity in vitro against Candida albicans of several supramolecular assemblies composed of drug, cationic lipid and/or polyelectrolytes were systematically evaluated by means of dynamic light scattering for particle sizing, zeta- potential analysis, UV-visible spectroscopy, effect of drug on gel-to-liquid-crystalline phase transition of the cationic bilayer and determination of drug loading. Supramolecular assemblies of antifungal drugs such as miconazole and amphotericin B were obtained by solubilization of the drugs in cationic bilayer fragments composed of dioctadecyldimethylammonium bromide or coverage of drug particles with a layer of the quoted cationic lipid. As a model of anticancer drug, cisplatin was sandwiched between two oppositely charged polyelectrolytes: chitosan and carboxymethylcellulose. Cisplatin induced reduction in particle size acting as a cross-linker between polyelectrolytes. For amphotericin B, at low and high molar proportion drug to cationic lipid, similar supramolecular assemblies were coated by polyelectrolytes such as carboxymethylcellulose, poly(diallyldimethylammonium) and polylysine yielding cationic nanoparticles that presented optimal colloid stability and fungicidal activity. Miconazole became attached at the hydrophobic edges of bilayer fragments at room temperature and/or, upon an increase in temperature, inserted in the bilayer core. Curiously, this last formulation in the cationic lipid yielded a synergistic action against Candida albicans. Dioctadecyldimethylammonium bromide (DODAB) is an excellent antimicrobial agents per se. Its mechanism of antimicrobial action was compared to the one for hexadecyltrimethylammonium bromide (CTAB). Adsorption of these compounds on the cells decreased going from CTAB to DODAB bilayer fragments and to large vesicles. Absence of leakage of small phosphorylated compounds, proteins or DNA from fungus indicated a mechanism of action different from cell lysis. Adsorption of the cationic compounds changed the sign of the cell zeta-potential from negative to positive. There was a clear relationship between positive charge on fungus and death.

A interação entre fragmentos de bicamada (BF) de brometo de dioctadecildimetilamônio (DODAB) e um mononucleotídeo-modelo (deoxiadenosina monofosfato, dAMP) ou um oligodeoxinucleotídeo-modelo (5\'- AAAAAAAAAA-3\', poli(dA)) ou um oligodeoxinucleotídeo terapêutico (5\'- TTGACGTTCG -3\', CpG) foi investigada por turbidimetria, espalhamento de luz dinâmico, espectroscopia de dicroísmo circular e de fluorescência e calorimetria diferencial de varredura (DSC). Respostas imunológicas foram caracterizadas com ensaio de hipersensibilidade tardia por inchamento de coxim patelar de camundongo, dosagem de anticorpos IgG1 e IgG2a e de citocinas secretadas por células de linfonodo em cultura. Poli(dA), em contraste com dAMP, induziu fusão máxima de DODAB BF a partir da neutralização de cargas, quando houve obtenção de um tamanho máximo e um potencial-zeta igual a zero para os arranjos. Para [poli(dA)] maiores do que aquela correspondente à neutralização de cargas, houve recuperação da estabilidade coloidal com reversão do potencial-zeta e com obtenção de tamanhos que foram aproximadamente o dobro daqueles determinados inicialmente para DODAB BF. A proporção molar de neutralização poli(dA): DODAB foi 1:10 para DODAB BF e 1:20 para vesículas grandes (LV) de DODAB, de acordo com as estruturas de bicamada aberta e fechada dessas duas dispersões de bicamada de DODAB. A fusão de DODAB BF induzida por poli(dA) foi extensiva aumentando o grau de empacotamento das bicamadas formadas conforme inferido a partir dos termogramas de DSC. Em condições de equivalencia de cargas, nucleotídeo não causou fusão de DODAB BF, mostrando a importância do caráter de polieletrólito do poli(dA) para induzir fusão. O sal divalente Na2HPO4 causou fusão e aumentou o empacotamento da bicamada graças à blindagem eficiente de cargas. Reestabilização coloidal como aquela induzida por poli(dA) não ocorreu em presença de Na2HPO4, NaCl ou nucleotídeo. Para complexos DODAB BF/CpG em presença de ovalbumina (OVA) como antígenomodelo, a neutralização de cargas de DODAB BF/OVA por CpG reduziu a estabilidade coloidal, enquanto que supercompensação de cargas levou à reestabilização por repulsão eletrostática, como observado para a interação DODAB BF/poli(dA). Diferenças no tamanho e nas proporções de neutralização por CpG indicaram que os fragmentos são capazes de carregar mais moléculas de OVA do que de BSA. Na região de supercompensação de cargas com potenciais-zeta negativos, arranjos Al(OH)3/ OVA/ CpG são coloidalmente bem mais instáveis que DODAB BF/ OVA ou DODAB BF / OVA/ CpG. O complexo negativamente carregado DODAB (0,1 mM) / OVA (0,1mg/mL)/ CpG (0,020 mM) potencializou a resposta Th1 obtida com DODAB (0,1 mM)/ OVA (0,1 mg/mL). Houve um aumento de 25 % no inchamento do coxim patelar, de 36 % na produção de IFN-γ, de 60 % de IL-12 e produção sustentada de IgG2a ao longo de 35 dias pós-imunização, todos indícios fortes de potencialização da resposta Th1 por CpG. Arranjos negativamente carregados de oligonucleotídeos em fragmentos de bicamada de DODAB possuem excelente potencial para terapias baseadas em oligonucleotídeos e para produção de vacinas para diferentes antígenos de interesse. / The interaction between bilayer fragments (BF) of dioctadecyldimethylammonium bromide (DODAB) and a model nucleotide (deoxyadenosine monophosphate, dAMP) or a model oligodeoxynucleotide (5\'- AAAAAAAAAA-3\', poly(dA)) or a therapeutic oligodeoxynucleotide (5\'- TTGACGTTCG -3\', CpG) was investigated by means of turbidimetry, dynamic light scattering, circular dichroism and fluorescence spectroscopies and differential scanning calorimetry. Immune responses were characterized using footpad swelling delayed type hipersensitivity assay and antibody and cytokine measurements. In contrast to dAMP, poly(dA) induced maximal DODAB BF fusion from charge neutralization, where assemblies presented maximal size and zero zeta-potential. Above charge neutralization colloid stability was recovered with negative zeta-potentials and sizes that were about the double of those initially determined for DODAB BF. The poly(dA):DODAB molar ratio for neutralization was 1:10 for DODAB BF and 1:20 for DODAB LV, in agreement with the open and closed bilayer structures of these two DODAB bilayer dispersions. The poly(dA)-induced DODAB BF fusion was extensive and increased the packing of the formed bilayers, as inferred from DSC thermograms. In conditions of charge equivalence, nucleotide did not cause DODAB BF fusion, highlighting the importance of poly(dA)\'s polyelectrolyte character to induce fusion. Divalent Na2HPO4 salt caused fusion and increased bilayer packing due to efficient BF charge shielding. Colloid restabilization as induced by poly(dA) was not observed in presence of Na2HPO4, NaCl and nucleotide. For DODAB BF/CpG complexes in presence of the ovalbumin (OVA) model antigen, the charge neutralization of DODAB BF/OVA by CpG reduced colloid stability, while charge overcompensation led to restabilization due to electrostatic repulsion, as observed for DODAB BF/poly(dA) interaction. Differences in size and neutralization proportions by CpG indicate that BF are able to load more OVA than BSA molecules. In the charge overcompensation region with negative zeta-potentials, Al(OH)3/OVA/CpG assemblies are colloidally less stable than DODAB BF/OVA or DODAB BF/OVA/CpG. The negatively charged DODAB (0.1mM)/OVA (0.1mg/ml)/CpG (0.020mM) assembly enhanced the Th1 response obtained with DODAB (0.1mM)/OVA (0.1mg/ml). There was a 25% increase in footpad sweeling, a 36% and 60% increase in the production of IFN-γ and IL-12 and sustained IgG2a production for the 35-day period after immunization, all indicative of strong Th1 response enhancement by CpG. Negatively charged assemblies of oligonucleotides in DODAB bilayer fragments have excellent potential in oligonucleotidebased therapies and in vaccine production for different antigens of interest.

This diploma thesis deals with the preparation and characterization of negatively charged catanionic vesicular systems and their combination with selected polycations. The catanionic vesicular system was prepared by mixing of two oppositely charged surfactants SDS and CTAB. The negative charge as well as the stability of the vesicular system was provided by the incorporation of phosphatidic acid. Polycations, DEAE and TMC, have been selected for use in a pharmaceutical applications. Characterization of the prepared systems was performed by measuring DLS and ELS. The results indicate that we were able to prepare stable negatively charged vesicles that were eligible to non-covalently interact with selected polycations.

This thesis studies the properties and behaviour of phase-separated hydrogels prepared by interaction of hyaluronan with oppositely charged surfactants. Three representatives of surfactants, namely cetyltrimethylammonium bromide, chloride and p-toluensulfonate (CTAB, CTAC, CTAT), were selected for comparison. Using the method of rheology, the fact that the system of Hya-CTAT forms the most rigid hydrogels has been proved. Higher molecular weight of hyaluronan has also direct influence on the volume and stiffness of the newly formed hydrogels. Preparation methods were compared as well. Mixing the stock solutions of entry components appeard to be the most suitable. Small-angle X-ray scattering was used for determination of shape and size of surfactant's micelles, concluding that it has no effect on the volume of formed gels. The results of this study indicate that given gels are to a certain extent competitive and incorporation of hyaluronan into their structure is desirable with respect to its biological activity. This offers a potential usage of these substances in the field of medical applications.