Os peptídeos hormonais vegetais, que vêm sendo caracterizados em plantas desde a década de 90, podem estar relacionados com defesa, reprodução, crescimento e desenvolvimento de plantas. O peptídeo RALF (Rapid Alkalinization Factor), ubíquo no reino vegetal, está envolvido com o desenvolvimento de plantas. Em arabidopsis há 37 genes que codificam peptídeos RALF (AtRALFs). A isoforma mais estudada é a AtRALF1, a qual regula de maneira negativa a expansão celular, inibindo o crescimento de raiz primária e o alongamento de hipocótilo quando aplicado exogenamente. Recentemente, demonstrou-se a existência de uma relação antagônica entre AtRALF1 e a via de brassinosteróides (BRs) no desenvolvimento de raízes. Quando mutantes da via de sinalização do BR foram avaliados quanto a sua resposta ao peptídeo AtRALF1, descobriu-se que mutantes para o receptor quinase1 associado ao BRI1 (bak1) são insensíveis a AtRALF1. Experimentos utilizando o sistema de duplo híbrido em levedura, a co-imunoprecipitação e a indução de genes marcadores em mutantes bak1 foram realizados e confirmaram o envolvimento da proteína BAK1 na percepção do peptídeo. Plantas transgênicas que superexpressam AtRALF1 apresentam um fenótipo semi-anão, no entanto, quando as mesmas foram cruzadas com o mutante bak1, suas progênies apresentaram um fenótipo similar ao de plantas selvagens. Ainda, quando plantas deste cruzamento foram novamente cruzadas com plantas selvagens, plantas com fenótipo semi-anão foram observadas na prole. Ensaios de ligação usando o peptídeo AtRALF1 marcado com éster de acridínio foram realizados e mostraram que em mutantes bak1, a ligação do AtRALF1 é menor em aproximadamente 30% quando comparada com plantas selvagens. Os dados obtidos mostram que a proteína BAK1 interage fisicamente com o AtRALF1, está envolvida na percepção do peptídeo, é essencial para a inibição do crescimento da raiz primária causada pelo AtRALF1 e é necessária para a indução dos genes responsivos ao AtRALF1. / The plant peptides, which have been characterized in plants since the 90\'s, can be related to defense, reproduction, growth and development of plants. The RALF (Rapid Alkalinization Factor) peptide, ubiquitous in the plant kingdom, is related to the development of plants. In arabidopsis plants, there are 37 genes encoding RALF peptides (AtRALFs). AtRALF1 is the most studied isoform, which negatively regulate cell expansion, inhibiting primary root growth and hypocotyl elongation when it is applied exogenously. Recently, an antagonistic relationship between AtRALF1 and the brassinosteroids (BRs) to control root development had been demonstrated. When the response of mutants related to the BR signaling pathway to AtRALF1 peptide was investigated, it was found that mutants lacking the BRI1-associated receptor kinase1 (bak1) are insensitive to AtRALF1. Experiments using the two-hybrid system in yeast, co-immunoprecipitation, and the induction of marker genes in bak1 mutants were carried out, and confirmed the involvement of the BAK1 protein in the perception of AtRALF1 peptide. Transgenic plants overexpressing AtRALF1 are semi-dwarf. However, when those transgenic plants were crossed with bak1 mutant, their progeny showed a wild-type phenotype. Besides, when plants from this progeny were crossed again with wild-type plants, semi-dwarf phenotype plants were obtained in the offspring. Binding assays using AtRALF1 labeled with acridinium-ester were performed, and showed that in bak1 mutants, the AtRALF1 binding was reduced approximately 30% when compared to wild-type plants. All data indicate that BAK1 protein interacts physically with AtRALF1, it\'s involved with the peptide perception, essential for the primary root growth inhibition caused by AtRALF1, and required to the induction of genes responsive to AtRALF1.

Os peptídeos da estaterina (DR9) e da histatina 3 (RR14), que ocorrem naturalmente na película in vivo, amplificam o efeito inibitório do crescimento de cristais de hidroxiapatita, função relacionada à remineralizarão do esmalte e formação de cálculos dentários. A hipótese da duplicação/hibridação de domínios funcionais dos peptídeos DR9 da estaterina e RR14 da histatina 3 foi testada. Para isto, os peptídeos peptidomiméticos (DR9-DR9, DR9-RR14), além deles individualmente e suas proteínas intactas (DR9, RR14, estaterina e histatina 3) foram estudados em sete concentrações diferentes para avaliar o efeito da inibição do crescimento de cristais de hidroxiapatita. Foi utilizado um ensaio colorimétrico de microplaca para quantificar o crescimento de cristais de hidroxiapatita. As experiências foram feitas em triplicata e a concentração inibitória (IC50) foi estabelecida para cada grupo. A IC50 foi calculada para todos os peptídeos e proteínas testados. A histatina 3 e o RR14 não atingiram o valor de IC50. O DR9- RR14 atingiu o valor de IC50 a 3,80 M. Como esperado, DR9 e DR9-DR9 demonstraram um efeito inibitório significativo na atividade de crescimento de cristais, atingindo o valor de IC50 a 2,82 M e 1,07 M, respectivamente. A estaterina atingiu o valor de IC50 a 2,50 M. Na análise estatística, foram aplicados os testes ANOVA e Student-Newman-Keuls para comparações por pares, para comparar os valores entre os grupos. O DR9-DR9 amplificou o efeito inibitório do crescimento de cristais de hidroxiapatita quando comparado com DR9 único (p <0,05), demonstrando que a multiplicação do domínio funcional é uma forte tendência evolutiva da proteína. De forma interessante, o peptídeo híbrido DR9-RR14 demonstrou um efeito inibitório intermediário quando comparado com outros dois grupos: DR9 único e DR9-DR9. Este estudo utilizou a abordagem peptidomimética para investigar uma via potencial de evolução da proteína relacionada com a duplicação/hibridação dos constituintes peptídicos naturais da película adquirida de esmalte. O conhecimento obtido por meio dos resultados deste trabalho pode fornecer uma base para o desenvolvimento de peptídeos sintéticos para uso terapêutico, tanto contra cárie dentária, como para a doença periodontal. / The statherin and histatin 3 peptides (DR9 and RR14 respectively), which occur naturally in the film in vivo, amplify the inhibitory effect for the growth of hydroxyapatite crystals, a function related to remineralization of the enamel and formation of dental calculi. The hypothesis of duplication/hybridization of functional domains of the DR9 peptides of the statherin and RR14 of histatin 3 was tested. For this, the peptidomimetic peptides (DR9-DR9, DR9-RR14), in addition to them individually and their intact proteins (DR9, RR14, statherin and histatin 3) were studied at seven different concentrations to evaluate the effect of growth inhibition of hydroxyapatite crystals. A colorimetric assay of microplate was used to quantify the growth of hydroxyapatite crystals. The experiments were done in triplicate and the inhibitory concentration (IC50) was established for each group. The IC50 was calculated for all peptides and proteins tested. Histatin 3 and RR14 did not reach the IC50 value. DR9-RR14 reached the IC50 value at 3.80 M. As expected, DR9 and DR9-DR9 demonstrated a significant inhibitory effect on crystal growth activity, reaching the IC50 value at 2.82 M and 1.07 M, respectively. Statherin reached the IC50 value at 2.50 M. ANOVA and Student-Newman-Keuls tests for paired comparisons were applied to compare the values between the groups. DR9-DR9 amplified the inhibitory effect of hydroxyapatite crystal growth when compared to single DR9 (p <0.05), demonstrating that the multiplication of the functional domain is a strong protein evolution pathway. Interestingly, the hybrid peptide DR9-RR14 demonstrated an intermediate inhibitory effect when compared to other two groups: single DR9 and DR9-DR9. This study utilized the peptidomimetic approach to investigate a potential pathway of protein evolution related to duplication/hybridization of the natural peptidic constituents of the acquired enamel film. The knowledge obtained through the results of this work can provide a basis for the development of synthetic peptides for therapeutic use, both against dental caries and for periodontal disease.

Este trabalho de Mestrado teve por objetivo avaliar a atividade antifúngica in vitro e em queijo Minas Padrão de duas formulações (A e B) de nanoemulsões encapsulando óleo essencial de orégano (Origanum vulgare) produzidas pelo método da temperatura de inversão de fases (método PIT). Cladosporium sp., Fusarium sp. e Penicillium sp. foram os fungos identificados nas amostras de queijo Minas Padrão deteriorados. Tais cepas foram utilizadas na avaliação da atividade antifúngica in vitro e em queijo Minas Padrão do óleo de orégano nanoemulsionado. Nos testes in vitro foram determinadas as concentrações mínimas inibitórias (CMI) do óleo essencial de orégano puro e nanoemulsionado sobre o Cladosporium sp., Fusarium sp. e Penicillium sp. Foram utilizadas fatias de queijo Minas Padrão para avaliar o efeito inibitório das nanoemulsões contendo óleo essencial de orégano. Por último foi avaliado o efeito inibitório das nanoemulsões durante o processo de maturação de queijos Minas Padrão. Determinaram-se valores de CMI para óleo essencial puro de 0,2; 0,3 µg/ml para Fusarium sp. e Penicillium sp., respectivamente. Enquanto para as duas formulações de nanoemulsão; os valores de CMI dependeram da quantidade de óleo essencial de orégano que estava contido nelas, obtendo-se valores de 0,26; 0,11 e 1,62 µg/ml para a formulação A de óleo de orégano nanoemulsionado sobre Cladosporium sp., Fusarium sp. e Penicillium sp., respectivamente, e CMIs de 0,32; 0,1 e 0,8 µg/ml para a formulação B de nanoemulsão sobre os mesmos gêneros de fungos. Os ensaios nas fatias de queijo evidenciaram que o efeito das CMIs, quando aplicadas na matriz alimentícia, foi nulo, permitindo o desenvolvimento normal dos fungos avaliados, da mesma forma se determinou a importância da atividade de água no crescimento fúngico. Já nos queijos em ambiente de maturação o efeito inibitório do óleo de orégano foi pouco satisfatório, o que indicou a importância do controle dos demais parâmetros ambientais no ambiente de maturação. Pode-se concluir que o óleo essencial de orégano nanoemulsionado apresentou efeito inibitório contra os gêneros de fungos avaliados. Quando controlados parâmetros ambientais como temperatura de armazenamento e atividade de água, seu efeito inibitório pode ser amplamente melhorado, apresentando-o como potencial alternativa na conservação dos alimentos. / This Master Thesis aimed to evaluate the in vitro antifungal activity and in Minas Padrão cheese of two formulations (A and B) of nanoemulsions encapsulating essential oil of oregano (Origanum vulgare) produced by the method of phase inversion temperature (PIT method). Cladosporium sp., Fusarium sp. and Penicillium sp. fungi were identified in deteriorated cheese samples. These strains were used in the evaluation of antifungal activity of oregano essential oil nanoemulsions, both in vitro and in cheese. Minimum inhibitory concentrations (MIC) of essential oil of pure oregano oil and nanoemulsions were determined. Cheese slices were used to evaluate the inhibitory effect of nanoemulsions containing essential oil of oregano. Finally the inhibitory effect of encapsulated oregano oil was tested during cheese ripening. MIC values determined for pure essential oil were 0.20 and 0.3 µg/ml for Fusarium sp. and Penicillium sp., respectively. As for the two nanoemulsion formulations, MIC values depended on the amount of essential oil of oregano which was contained therein, and the values for formulation A were 0.26, 0.11 and 1.62 µg/ml for Cladosporium sp., Fusarium sp. and Penicillium sp, respectively. For formulation B, the values of MIC were 0.32, 0.10 and 0.80 µg/ml. The tests on the cheese slices showed that the effect of MIC when applied in the food matrix was null, as the fungi growth was not avoided. As for the tests during cheese ripening, the inhibitory effect of oregano oil in nanoemulsions was unsatisfactory, which indicated the importance of controlling other environmental parameters in the maturation chamber. It can be concluded that the nanoemulsions of essential oil presented inhibitory effect against the genera of fungi evaluated. Controlled environmental parameters such as storage temperature and water activity, its inhibitory effect can be highly improved, and the nanoemulsions of oregano oil can be seen as a potential system for food preservation.

Bacillus subtilis is a gram positive soil bacterium that is surrounded by many other microorganisms its environment. That is why it is necessary for the bacterium to be able to fight with these microorganisms for the nutrients and living space. B. subtilis contains the modules in its genetic make-up that improve its ability to compete. These modules are called the toxin-antitoxin systems. This Diploma Thesis is trying to identify yet undescribed extracellular toxins produced by the wild type BSB1 strain of B. subtilis. The related microorganism Bacillus megaterium was used as a competing bacterium. The contact-dependent or independent manner of killing the competing bacterium was demonstrated using this model. By deletion analysis and comparisons of the genomes of the various strains of B. subtilis, the SPβ prophage was first identified as a region containing an unknown toxin(s). Analysis of the extracellular proteome of B. subtilis subsequently revealed an unknown toxin (or toxin complex, respectively) of the molecular weight exceeding 100 kDa. Even more fascinating was the finding that such a large protein molecule is resistant to the pancreatic protease, trypsin. Subsequent non-enzymatic cyanogen bromide cleavage of the extracellular proteins and their analysis by mass spectrometry revealed...

The antifouling paint Fabi 3959 is painted on the hulls of vessels to avoid fouling caused by marine organisms attached to surfaces. The paint is registered for use on pleasure boats and other vessels weighing over 200 kg which are mainly running on the Swedish west coast (www.kemi.se). Fabi 3959 contains copper as its active component, which is highly toxic to marine organisms and thus classified as a biocide. Fabi antifouling paint was tested under laboratory conditions on the red macro alga Ceramium tenuicorne, in natural brackish water taken from the Baltic Sea. The Ceramium growth inhibition-test was performed using cloned algae exposed to leakage water with and without sediment. The samples containing only water held concentrations in the range of 0.11% of volume-18% of volume per liter, while the samples using sediment held doses measuring between 0.11% of volume-36% of volume leakage water per liter. The study showed a growth inhibiting effect on the Ceramium in both water and sediment samples down to the lowest concentration used in the test. There was a difference between the water series and the sediment series in the EC50 values of the leakage water. The mean EC50 value was almost 10 times lower within the sediment series compared to the water series (0.114±0.10 and 1.024±0.75, respectively). This indicates that the sediment series are more toxic to Ceramium than the water series. However, if the mean values of EC50 are expressed as copper-concentration, there is no clear difference between the two series (0.59 ± 0.13µg/l for the sediment series and 0.62 ± 0.12 µg/l for the water series). Apparently, the test did not indicate that the sediment was absorbing the copper. Instead it cannot be excluded that another substance involved could have a growth inhibiting impact on Ceramium. / Båtbottenfärgen Fabi 3959 målas på fartygsskrov för att undvika påväxt av marina organismer. Färgen är registrerad att användas på fritidsbåtar och andra fartyg med en egenvikt på över 200 kg och med huvudsaklig fart på Västkusten (www.kemi.se). Den aktiva komponenten i Fabi 3959 är koppar, vilket är mycket giftigt för marina organismer och därför klassificeras den som en biocid. Fabi båtbottenfärg testades i laborativ miljö, på den röda makroalgen Ceramium tenuicorne i naturligt brackvatten från Östersjön. Ett tillväxthämningstest utfördes på Ceramium-kloner vilka exponerades för lakvatten i bägare med och utan sediment. Proverna endast innehållande vatten bestod av koncentrationer i intervallen 0,11-18 volym% per liter medan proverna med sedimentvatten hade koncentrationer på 0,11-36 volym% per liter. Studien visade på en signifikant tillväxthämningseffekt på Ceramium i både vatten och sediment, ner till den lägsta använda koncentrationen. Det förelåg en tydlig skillnad mellan vattenserierna och sedimentserierna med avseende på resultaten av EC50-värdena på lakvattnet; EC50-värdena av den toxiska nivån för lakvattnet visade sig ligga tio gånger lägre i sedimentserierna än i vattenserierna (0,114 ± 0,10 i sediment och 1,024 ± 0,75 i vatten). Medelvärdena av EC50 för koppar visar inte någon påtaglig skillnad mellan serierna (0,59 ± 0,13µg/l för sediment 0,62 ± 0,12 µg/l för vatten). Testet indikerade därmed inte att sedimentet absorberade koppar. Istället föreligger en möjlighet att en annan substans orsakade tillväxthämning på Ceramium.

<p>The PRLs are a subfamily of dual specificity phosphatases that appear to play important roles in oncogenesis. Much of the current understanding of PRL function has been either correlative, and deduced from observed PRL overexpression in pathological conditions, or from in vitro analysis of signaling pathways following PRL deletion or overexpression. Such studies, necessitated by the general lack of synthetic inhibitors or compounds to probe the substrate specificity and biological interactions of the PRLs, are nonetheless now providing critical insight into potential biological substrates and roles of the PRL phosphatases. The recent identification of PTEN as a substrate for PRL2 provided the foundation for studies to further define the role of PRL2 in oncogenesis and, by analogy, the normal physiological function of PRL2. In the studies described herein, a novel PRL2 conditional knock-out animal was generated and used to validate the PRL2/PTEN interaction in a leukemic phenotype, and further demonstrated that PRL2 inhibition can restore dysregulated PTEN/AKT pathways to significantly attenuate disease progression. Inhibition of PRL2 therefore represents a novel potential therapeutic strategy in the management and treatment of AML. This thesis project also sought to further examine the role of the PRLs in oncogenesis through their regulation and interaction of targets within the TME. Functional analyses revealed that PRL3 was the only PRL to have a prominent role in host response to TME development, and that previously proposed roles for PRL3 in angiogenesis and immune cell recruitment is dependent upon PRL3 expression and activity in cells external to the TME. The study also revealed a previously unrecognized synergism between VEGF and PRL3 in the host in promoting TME angiogenesis. The studies of PRL3 in the TME suggest the potential physiological role of PRL3 in wound healing.</p>

No description available.

Submitted in complete fulfillment for the Degree of Doctorate of Philosophy in Biotechnology, Durban University of Technology, Durban, South Africa, 2016. / Plants have provided a source of medicine from the beginning of human history and are the core of modern medicine. Moreover, plant based drug discovery has led to the development of various anticancer drugs (such as vincristine, vinblastine, etoposide, paclitaxel, camptothecin, topotecan and irinotecan). The use of botanical, phytochemical, biological and molecular techniques have facilitated the discovery of anthraquinones from Ceratotheca triloba that can inhibit the human topoisomerase II enzyme (target for anticancer drugs) and kill cancer cells. However, the C. triloba plant has not been extensively studied for its anticancer activity. Therefore, the aim of this study was to further investigate the anticancer activity of C. triloba and determine the classes of compounds that contributed towards its activity. In this study the leaf and root extracts were prepared by using hexane, DCM, hexane: DCM (1:1), methanol and/or water. These extracts were examined for their growth inhibitory potential on three cancer cell lines (A375 [melanoma], MDA-MB-231[breast] and WHCO1 [esophageal]) by using the MTT assay. Then, different mobile phases were prepared for optimizing the separation of the compounds of the active extract by TLC. Column chromatography was performed with the active extract by using five mobile phases (hexane : DCM [60 : 40, 40 : 60], DCM, DCM : ethyl acetate [90 : 10, 70 : 30, 60 : 40, 50 : 50, 50 : 60, 30: 60, 20 : 80], ethyl acetate and ethyl acetate: methanol [80 : 20, 70 : 30, 50 : 50]). The fractions collected from the column were examined for their growth inhibitory potential on two melanoma cell lines (A375 and UACC-62). The IC50 and TGI (total growth inhibition) values of the active fractions were determined. Also, the apoptosis inducing effects of the active fractions and standards (camptothecin and doxorubicin) were determined by using flow cytometer based assays (FITC annexin assay, PE active caspase 3 assay and BD MitoScreen assay). Subsequently, the chemical structures of the compounds that contributed towards the activity of these fractions were obtained by EI-LC-MS analysis. The results demonstrated that the hexane root extract exhibited the best percentage of growth inhibition (%GI) on all three cancer cell lines. The separation of the compounds of the hexane root extract was optimized on TLC plates by using different ratios of hexane and DCM. Column chromatography allowed for fractionation of this extract. Purified compounds were not obtained due to co-elution. Further research would have to be conducted to obtain purified compounds. This may involve the use of mini-column chromatography and PTLC. Overall a total of ten combined fractions were collected from the column. Four of these fractions (F2, F4, F5 and F8) displayed a high %GI on the A375 and UACC-62 cell lines. Moreover, fraction F4 was the most active fraction as it had the lowest IC50 (0.70 µg.ml-1 [A375] and 0.39 µg.ml-1 [UACC-62]) and TGI (12.50 µg.ml-1[A375] and 25 µg.ml-1 [UACC-62]) values in comparison to the other fractions. All four fractions induced depolarization of the mitochondria membrane potential (ΔΨ), caspase 3 activation, early apoptosis (phospholipid phosphatidylserine exposure) and/or late apoptosis in the melanoma cells. The results also revealed that fraction F4 (25 µg.ml-1) induced depolarization of the ΔΨ in a higher percentage of A375 (78.11%) and UACC-62 (87.4%) cells than the other fractions and standards. This fraction also induced caspase 3 activation in a high percentage of A375 (90.56%) and UACC-62 (96.78%) cells. Therefore fraction F4 was also the most active fraction in terms of apoptosis activity. Based on our results and literature findings we can deduce that the active fractions induced the intrinsic or extrinsic (type II) apoptosis pathway in the melanoma cells. Six classes of compounds were identified from the four active fractions. These were: benzothiophenones, benzopyranones, naphthoquinones, anthraquinones, androstanes and quinazolines. In conclusion, this is the first study that evaluated the growth inhibition potential of the leaf and root extracts of C. triloba on a panel of cancer cells. This research indicated that the hexane root extract displayed the best levels of cell growth inhibition. The active constituents of this extract were isolated into four fractions which elicited apoptosis inducing effects that promoted the extrinsic (type II) or intrinsic apoptosis pathway in the melanoma cells. Furthermore, fraction F4 contained the most active compounds from C. triloba as it had the lowest IC50 and TGI values (in comparison to the other fractions) and induced depolarization of the ΔΨ in the highest percentage of melanoma cells. It was confirmed that six classes of compounds were accountable for the anticancer activity of these fractions. Thus, the C. triloba plant is a rich source of anticancer compounds. / D

Le papier bioactif est obtenu par la modification de substrat du papier avec des biomolécules et des réactifs. Ce type de papier est utilisé dans le développement de nouveaux biocapteurs qui sont portables, jetables et économiques visant à capturer, détecter et dans certains cas, désactiver les agents pathogènes. Généralement les papiers bioactifs sont fabriqués par l’incorporation de biomolécules telles que les enzymes et les anticorps sur la surface du papier. L’immobilisation de ces biomolécules sur les surfaces solides est largement utilisée pour différentes applications de diagnostic comme dans immunocapteurs et immunoessais mais en raison de la nature sensible des enzymes, leur intégration au papier à grande échelle a rencontré plusieurs difficultés surtout dans les conditions industrielles. Pendant ce temps, les microcapsules sont une plate-forme intéressante pour l’immobilisation des enzymes et aussi assez efficace pour permettre à la fonctionnalisation du papier à grande échelle car le papier peut être facilement recouvert avec une couche de telles microcapsules. Dans cette étude, nous avons développé une plate-forme générique utilisant des microcapsules à base d’alginate qui peuvent être appliquées aux procédés usuels de production de papier bioactif et antibactérien avec la capacité de capturer des pathogènes à sa surface et de les désactiver grâce à la production d’un réactif anti-pathogène. La conception de cette plate-forme antibactérienne est basée sur la production constante de peroxyde d’hydrogène en tant qu’agent antibactérien à l’intérieur des microcapsules d’alginate. Cette production de peroxyde d’hydrogène est obtenue par oxydation du glucose catalysée par la glucose oxydase encapsulée à l’intérieur des billes d’alginate. Les différentes étapes de cette étude comprennent le piégeage de la glucose oxydase à l’intérieur des microcapsules d’alginate, l’activation et le renforcement de la surface des microcapsules par ajout d’une couche supplémentaire de chitosan, la vérification de la possibilité d’immobilisation des anticorps (immunoglobulines G humaine comme une modèle d’anticorps) sur la surface des microcapsules et enfin, l’évaluation des propriétés antibactériennes de cette plate-forme vis-à-vis l’Escherichia coli K-12 (E. coli K-12) en tant qu’un représentant des agents pathogènes. Après avoir effectué chaque étape, certaines mesures et observations ont été faites en utilisant diverses méthodes et techniques analytiques telles que la méthode de Bradford pour dosage des protéines, l’électroanalyse d’oxygène, la microscopie optique et confocale à balayage laser (CLSM), la spectrométrie de masse avec désorption laser assistée par matrice- temps de vol (MALDI-TOF-MS), etc. Les essais appropriés ont été effectués pour valider la réussite de modification des microcapsules et pour confirmer à ce fait que la glucose oxydase est toujours active après chaque étape de modification. L’activité enzymatique spécifique de la glucose oxydase après l’encapsulation a été évaluée à 120±30 U/g. Aussi, des efforts ont été faits pour immobiliser la glucose oxydase sur des nanoparticules d’or avec deux tailles différentes de diamètre (10,9 nm et 50 nm) afin d’améliorer l’activité enzymatique et augmenter l’efficacité d’encapsulation. Les résultats obtenus lors de cette étude démontrent les modifications réussies sur les microcapsules d’alginate et aussi une réponse favorable de cette plate-forme antibactérienne concernant la désactivation de E. coli K-12. La concentration efficace de l’activité enzymatique afin de désactivation de cet agent pathogénique modèle a été déterminée à 1.3×10-2 U/ml pour une concentration de 6.7×108 cellules/ml de bactéries. D’autres études sont nécessaires pour évaluer l’efficacité de l’anticorps immobilisé dans la désactivation des agents pathogènes et également intégrer la plate-forme sur le papier et valider l’efficacité du système une fois qu’il est déposé sur papier. / Bioactive paper is obtained through the modification of paper substrate with biomolecules and reagents. It is used in the development of novel biosensors that are portable, disposable and inexpensive, aimed at capturing, detecting and in some cases deactivating pathogens. Generally bioactive papers are made by incorporating biomolecules such as enzymes and/or antibodies on to paper. The immobilization of such biomolecules on solid surfaces is widely used for different diagnostic applications such as in immunosensors and immunoassays but due to the sensitive nature of enzymes, their large scale incorporation into paper has faced several difficulties especially under industrial papermaking conditions. The functionalization of paper at large scale is possible because paper can be easily coated with a layer of microcapsules, which have proven to be an efficient immobilization platform for enzymes and to allow. In this study, we developed a generic alginate-based platform incorporating microcapsules that can be applied to current paper production processes to prepare antibacterial bioactive paper with the ability to capture pathogens on its surface and to deactivate them by producing an anti-pathogenic agent. The design of the antibacterial platform is based on constant production of hydrogen peroxide as the antibacterial agent inside the alginate microcapsules. Hydrogen peroxide production is achieved through oxidation of glucose, catalyzed by the enzyme glucose oxidase encapsulated inside the alginate beads. The different steps of development included the entrapment of glucose oxidase inside alginate microcapsules, the reinforcement and surface activation of microcapsules by adding an additional layer of chitosan, investigating the possibility of immobilization of antibodies (human immunoglobulin G as a model antibody) on the surface of microcapsules and, finally, verifying the antibacterial properties of the system against Escherichia coli K-12 (E. coli K-12) as a representative pathogen. During development, certain measurements and observations were made using various analytical methods and techniques such as Bradford protein assay, oxygen electroanalysis, optical and confocal laser canning microscopy (CLSM), matrix assisted laser desorption/ionization- time of flight mass spectrometry (MALDI-TOF-MS), etc. Appropriate tests were performed to validate the successful modification of microcapsules and to ensure that glucose oxidase is still active after each modification. It was found that the encapsulated glucose oxidase maintained the specific enzymatic activity of 120±30 U/g. Subsequent efforts were made to immobilize glucose oxidase on gold NPs of two different diameters (10.9 nm and 50 nm) to enhance the enzymatic activity and increase the encapsulation efficiency. The results obtained during this study demonstrate successful modifications on alginate microcapsules and also a successful response of such antibacterial platform regarding deactivation of the pathogen representative, E. coli K-12. The threshold for the enzymatic activity was found to be 1.3×10-2 U/ml for E. coli K-12 growth inhibition of 6.7×108 cells/ml. Further studies are needed to assess the efficiency of immobilized antibody in the capture of pathogens and also to incorporate the platform onto paper and to validate the efficiency of the system once it is coated on paper.

Realizou-se a pesquisa de anticorpos aglutinantes (AcA) anti-leptospira, através da técnica de soroaglutinação microscópica (SAM) e tentativas de isolamento do agente etiológico em 29 cães com suspeita clínica de leptospirose. Foi também realizada a pesquisa de material genético de Leptospira spp., utilizando-se a técnica de reação em cadeia de polimerase (PCR) em 24 amostras de urina dos mesmos cães. Com o objetivo de determinar a proteção cruzada entre os sorovares icterohaemorrhagiae e copenhageni, 24 cães adultos foram avaliados antes e após a vacinação com uma dose de vacina contendo os antígenos icterohaemorrhagiae, canicola, grippotyphosa e pomona, utilizando-se o teste de inibição de crescimento in vitro (TIC) dos sorovares canicola, copenhageni e icterohaemorrhagiae. Os títulos de AcA anti-copenhageni foram os mais freqüentemente observados nos cães com suspeita clínica de leptospirose, havendo entretanto, reação cruzada entre diferentes sorovares. Foram isoladas quatro amostras de leptospira, das quais três foram caracterizadas por anticorpos policlonais e por Variable Number Tandem Repeat (VNTR) como sorovar canicola. A quarta amostra isolada reagiu em alto título com o anti-soro policlonal anti-sorovar copenhageni (51.200), não tendo sido testado com o anti-soro anti-icterohaemorrhagiae. Pela técnica de VNTR, essa amostra foi classificada como pertencente ao sorogrupo icterohaemorrhagiae e, finalmente, pelo uso dos anticorpos monoclonais F70 C24, F70 C14-10, F12 C3-11 e F89 C12, para a diferenciação dos representantes do sorogrupo icterohaemorrhagiae, essa amostra isolada apresentou o comportamento imunológico do sorovar copenhageni (cepa padrão L1 130, FIOCRUZ - Bahia). Considerando-se como critério sorológico de confirmação do diagnóstico clínico de leptospirose, títulos maiores ou iguais a 800 em amostra única de soro, ou o aumento ou declínio de quatro vezes os títulos de AcA (duas diluições) em duas amostras pareadas de soro, houve a confirmação do diagnóstico etiológico em 9 de 24 cães (37,5%) pela SAM. Por outro lado, 11 das 24 amostras de urina (45,8%) foram positivas à PCR. A associação das duas técnicas permitiu a confirmação diagnóstica em 15 cães (62,5%). Os títulos de anticorpos neutralizantes (AcN) (TL50) pré-vacinais contra os sorovares icterohaemorrhagiae, canicola e copenhageni foram respectivamente de 1,444±0,278, 0,725±0,317 e 0,583±0,322, e os títulos pós-vacinais foram respectivamente de 1,455±0,287, 1,475±0,270 e 0,510±0,304. Considerando-se o título de AcN maior ou igual a 1 como título protetor contra a infecção leptospírica, no momento pré-vacinal, os cães ainda apresentavam AcN contra o sorovar icterohaemorrhagiae capazes de protegê-los contra a infecção natural, não tendo havido também uma resposta adicional ao estímulo vacinal. Com relação ao sorovar canicola, houve aumento significativo dos títulos de AcN após a imunização (p=0,001) quando comparado ao momento pré-vacinal, tendo sido desenvolvida uma resposta protetora. Embora os animais não tenham sido vacinados contra o sorovar copenhageni, a presença de AcN pré-vacinal e pós-vacinal pode ser justificada pela reatividade cruzada entre ambos, copenhageni e icterohaemorrhagiae, pertencentes ao mesmo sorogrupo; entretanto os títulos pré- e pós-vacinais não foram da mesma magnitude dos produzidos contra o sorovar icterohaemorrhagiae. Portanto, a vacina contendo bacterina do sorovar icterohaemorrhagiae não é capaz de eliciar resposta protetora contra o sorovar heterólogo copenhageni. / A research on agglutinating antibodies (AAc) anti-leptospira has been performed, through microscopic agglutination test (MAT) and attempts of isolation of the etiologic agent in 29 dogs with clinical suspicious of leptospirosis. There was also made a research of Leptospira spp.´s genetic material, using polimerase chain reaction (PCR) in 24 urine samples of the same dogs. With the aim to determine the cross protection between serovars icterohaemorrhagiae and copenhageni, 24 adult dogs were evaluated before and after vaccination with one dose of a vaccine containing icterohaemorrhagiae, canicola, grippotyphosa and pomona antigens, by the in vitro inhibition growth test (GIT) of serovars canicola, icterohaemorrhagiae and copenhageni. The AAc anti-copenhageni titers were the most frequently obseeved in the dogs with clinical suspicious of leptospirosis, existing however, cross reaction among different serovars. There were isolated four samplas of leptospira, of witch three were all characterizated by polyclonal antibodies and Variable Nunber Tandem Repeat (VNTR) as serovar canicola. The fourth isolated sample reacted in high titers to polyclonal antisera anti-copenhageno (51.200), but is was not tested with antisera anti-icterohaemorrhagiae. By VNTR technique, this sample was classified as belonging to the serogroup icterohaemorrhagiae, and finally by the use of monoclonal antibodies F70 C24, F70 C14-10, F12 C3-11 and F89 C12, for differentiation of the representatives of serogroup icterohaemorrhagiae. This isolated sample presented the immunological behavior of serovar copenhageni (standard strain LI 130, FIOCRUZ - Bahia). Considering the sorologic criteria confirmation of clinical diagnosis of leptospirosis, titers higher or equal than 800 in a unique serum sample, or the increase or decrease of four times of AAc titers (two dilutions) in two paired serum samples, there was the conformation of etiologic diagnosis in 9 of the 24 dogs (37,5%) by MAT. However, 11 out of 24 urine samples (45,8%) were positive at PCR. The association of both techniques allowed the diagnostic conformation in 15 dogs (62,5%). The prevaccinal neutralizing antibodies (NAc) titers (TL50) were respectively 1,444±0,278, 0,725±0,317 and 0,583±0,322. And the postvaccinal titers were respectively 1,455±0,287, 1,475±0,270 and 0,510±0,304. Considering the NAc titer higher than 1 as a protective titer against leptospiral infection, at prevaccinal moment the dogs still presented NAc against serovar icterohaemorrhagiae capable to protect them against natural infection, an adictional response to the vaccinal stimulus had not occurred. Concerning serovar canicola, there was a significant increase of NAc titers after immunization (p=0,001) when compared to prevaccinal moment, and a protective response was developed. Although the animals were not vacinated against serovar copenhageni, the presence of prevaccinal and postvaccinal NAc can be explained by cross reactivity between both, copenhageni and icterohaemorrhagiae, belonging to same serogroup; however, the pre- and postvaccinal titers were not of the same magnitude of those produced against serovar icterohaemorrhagiae. Therefore, the vaccine containing bacterins of serovar icterohaemorrhagiae is not capable of eliciting protective response against the heterologous serovar copenhageni.