Made available in DSpace on 2015-03-04T18:58:02Z (GMT). No. of bitstreams: 1 thesis (1).pdf: 2502829 bytes, checksum: 20035b341686418a94516986bc16b476 (MD5) Previous issue date: 2013-11-22 / In this dissertation, we present a detailed study of the model proposed by Hinow et al. 2009, in which, through a continuum model based on equations of reaction-diffusion type, the authors simulate the spatial dynamics of tumor growth. The dynamics of proliferating, hypoxic, necrotic and endothelial cells, extracellular matrix and nutrients are included in this model. An angiogenesis model is also included, allowing the evaluation of different treatment protocols for cancer through antiangiogenic and cytotoxic drugs. Numerical and computational models have been developed for this class of models. Further examination of the model from Hinow et al. 2009 indicated some inconsistencies in the model. By adding new hypotheses, a new model is developed, overcoming the observed non-biological behaviors. The new model aggregates new dynamics, including the interactions between healthy cells and other tissues. One of the major contribution of this model is the proposal of a haptotactic term responsible for the directional movement of healthy cells towards dead cells. The inclusion of such term provides a more realistic approach to the treatment of the disease. As an example, healthy cells are able to return to regions formerly occupied by the tumor after a successful cytotoxic treatment. Several numerical experiments are presented to justify the development of such model and to show its behavior when different treatment protocols for the disease are considered. / Nesta dissertacao de mestrado apresentamos um estudo detalhado do modelo proposto por Hinow et al. 2009, no qual os autores por meio de um modelo continuo baseado em equacoes do tipo reacao-difusao simulam a dinamica espacial do crescimento tumoral. Neste modelo sao incluidas as dinamicas das celulas proliferativas, hipoxicas, necroticas e endoteliais, alem da matriz extracelular e de nutrientes. Um modelo de angiogenese e tambem incluido, permitindo a avaliacao de diferentes protocolos de tratamento da doenca por meio de drogas antiangiogenicas e citotoxicas. Modelos numericos e computacionais foram desenvolvidos para esta classe de modelos tendo como base formulacoes consistentes de elementos finitos. O estudo aprofundado do modelo de Hinow et al. 2009 indicou algumas inconsist^encias. A partir da inclusao de novas hipoteses um novo modelo foi desenvolvido, eliminando as situacoes nao-biologicas observadas. O novo modelo agrega novas dinamicas, incluindo as interacoes das celulas saudaveis com as demais do tecido. Uma das maiores contribuicoes do novo modelo proposto e a consideracao de um termo haptotatico responsavel pelo movimento direcional das celulas saudaveis na direcao das celulas mortas. A inclusao de tal termo propiciou uma abordagem mais realista do tratamento da doenca, captando por exemplo, apos o tratamento citotoxico, a retomada pelas celulas saudaveis da regiao outrora ocupada pelo tumor. Diversos experimentos numericos sao apresentados para justificar o desenvolvimento de tal modelo, assim como a simulacao de diversos protocolos de tratamento da doenca.

Neste trabalho nós aplicamos resultados recentes na área de rotinas ótimas de inspeção sob deterioração estocástica ao problema do estabelecimento de uma rotina de testes clínicos a que deve submeter toda uma população visando detectar tão cedo quanto possível a eventual presença de um certo tipo de vírus em cada elemento dessa população. Aqui nós consideramos a existência de dois tipos de exames laboratoriais. O primeiro é mais barato, porém menos confiável, pois pode gerar falsos resultados positivos ou falsos resultados negativos. Sempre que esse exame gera um resultado positivo usamos um segundo tipo de exame, mais caro e mais preciso, para verificar se tal resultado é verdadeiro ou falso. Se verdadeiro, submete -se o sistema a um tratamento para evitar a condição de quebra (falha, morte) do mesmo. Com uma estrutura de custos que considera custos de: examina, falsos resultados positivos; detecção do vírus e ficar doente, nós apresentamos uma equação que pode se usada para calcular o valor presente do custo esperado total sob uma determinada rotina de exames. A incorporação da possibilidade de um falso resultado negativo é a maior contribuição teórica deste trabalho.Usando dados reais, o modelo é aplicado ao problema da detecção do vírus da AIDS em países como o Brasil ou os Estados Unidos, onde a doença se manifesta de maneira semelhante. O resultado principal é a obtenção da freqüência de inspeções que minimiza o valor presente do custo esperado total.

Orientador: Clélia Akiko Hiruma Lima / Coorientador: Lúcia Regina Machado da Rocha / Banca: Cláudia Helena Pellizzon / Banca: Luis Vitor Silva Sacramento / Resumo: Cissus sicyoides (Linneu) pertencente à família Vitaceae é uma planta nativa do Caribe, América do Sul e especialmente no Brasil, onde é conhecida como ―Insulina vegetal‖. O chá das folhas desta espécie é utilizada popularmente como anti-inflamatório, anti-hipertensivo, antitérmico, antidiabético, antireumático, contra infecções respiratórias, dislipidemias, distúrbios gastrointestinais e indigestão, para anemia, acidente vascular cerebral, tremores e como ativador da circulação sanguínea. A análise fitoquímica das partes aéreas de C. sicyoides mostra a presença de flavonóides glicosilados, e várias atividades biológicas já foram descritas para esta espécie, dentre elas, atividade gastroprotetora do extrato metanólico de suas folhas. O objetivo deste trabalho foi investigar a atividade antiulcerogênica do extrato hidroalcoólico das folhas de C. sicyoides (EHCS), elucidar os mecanismos envolvidos no efeito antiulcerogênico, em processos inflamatórios e em modelos experimentais de diarreia em roedores. A administração oral do EHCS nas doses 250 e 500 mg/Kg protegeu a mucosa gástrica da ação dos agentes lesivos etanol e anti-inflamatório não esteroidal em ratos Wistar machos. O EHCS na menor dose efetiva (250 mg/Kg) não alterou os parâmetros bioquímicos do suco gástrico em modelo de ligadura do piloro e não preveniu a úlcera duodenal induzida por cisteamina hidroclorídrica. Este extrato aumentou a quantidade de muco aderido à parede gástrica, restabeleceu o fluxo sanguíneo atuando como regulador na microcirculação e a ação gastroprotetora do extrato é dependente de óxido nítrico por atuação da enzima óxido nítrico sintase induzível (iNOS), ao mesmo tempo que independe de grupamentos sulfidrilas e receptores vanilóides. Este extrato possui propriedade antioxidante ao promover a proteção das lesões gástricas induzidas por isquemia-reperfusão, reduzindo ... / Abstract: Cissus sicyoides (Linneu) belongs to the Vitaceae family is a plant native to the Caribbean, South America and especially in Brazil, where it is known as "vegetable insulin". The tea from leaves of this species is popularly used as anti-inflammatory, anti-hypertensive, antipyretic, antidiabetic, antirheumatic, against respiratory infections, dyslipidemia, gastrointestinal disorders and indigestion, for anemia, cerebral tremors and as an activator of circulation blood. The phytochemical analysis of aerial parts of C. sicyoides showed predominantly the presence of glycosylated flavonoids and various biological activities have been described for this species, among them, gastroprotective activity of the methanol extract of its leaves. With these considerations, the aim of this study was to investigate the antiulcer activity of hydroalcoholic extract of C. sicyoides (HECS), as well as to elucidate the mechanisms involved in antiulcerogenic effect, inflammatory processes and in experimental models of diarrhea in rodents. The HECS in doses 250 and 500 mg/Kg protected the gastric mucosa from the damaging agents action, ethanol and anti-inflammatory non-steroidal when administered orally to male Wistar rats. The EHCS at the lowest effective dose (250 mg/Kg) didn't alter biochemical parameters of gastric juice in pylorus ligature model and did not prevent the duodenal ulcer induced by cysteamine hidroclorídrica. This extract increased the amount of mucus adhered to the gastric wall, restored blood flow in the microcirculation acting as a regulator and gastroprotective activity of the extract is dependent on nitric oxide activity of the enzyme inducible nitric oxide synthase (iNOS), while independent groups of sulfhydryl and vanilloid receptors. This extract has antioxidant properties to promote the protection of gastric lesions induced by ischemia-reperfusion injury by reducing lipid peroxidation (LPO) and ... / Mestre

The biopharmaceutical market has been on the rise for the past two decades and is expected to continue to excel, currently presenting a growing rate of more than double than conventional pharma. Traditionally this growth has been hindered by multiple formulation issues such as poor bioavailability and poor stability. Consequently, the drive to optimise the stability of protein drug candidates via formulation impels the need for development of novel excipients. Novel glycopolymer excipients were reported to confer improved protein stability in selected cases. Nonetheless,their structure-function relationship and wider applicability remain largely unknown. Here we report the synthesis of glycopolymers with different molecular architectures based on mannose, galactose, arabinose, N-acetyl glucosamine, lactose and trehalose, and nvestigate their utility as excipients for the solution formulation of a monoclonal antibody (mAb). In this thesis work the physical stability of selected antibodies was measured as the unfolding transition temperature (Tm) and aggregation onset temperature (Tagg), as a function of glycopolymer properties, such as the nature of sugar repeating unit, macromolecular architecture and concentration. Results show that, in contrast to the stabilising effect of the corresponding mono- and di-saccharide constituents, both linear and 4-arm star glycopolymers generally destabilised the antibody, decreasing both Tm and Tagg. Accelerated stability studies of a concentrated mAb solution followed the same trend, where an increasing glycopolymer:mAb molar ratio generally decreased the percentage monomer(i.e. increased soluble aggregates). Importantly, trehalose-based glycopolymers further generated visible aggregates that could not be predicted from Tm or Tagg data. The data demonstrate a complex interplay of sugar chemistry and solution concentration of synthetic glycopolymers on their modulation of protein conformational stability and aggregation propensity. The mechanisms involved in protein:glycopolymer interaction, both in solution and dry state were further investigated, thus unravelling the behaviour reported in terms of protein stabilisation. Finally, the glycopolymers were studied as drug delivery systems, acting as solubility enhancers for hydrophobic species in aqueous solutions, through the use of extrinsic fluorescent dyes.

Orientador: Taís Maria Bauab / Banca: Izabela Dutra Alvim / Banca: Carlos Henrique Gomes Martins / Resumo: Os fitoterápicos têm apresentado resultados surpreendentes no tratamento de doenças crônicas, principalmente do trato digestório (úlceras gástricas e duodenais, colite ulcerativa e doença de Crohn), diabetes e câncer. A Política Nacional de Plantas Medicinais e Fitoterápicos - PNPMF (Ministério da Saúde - MS) propõe o estudo de diversas espécies vegetais, dentre estas, plantas do gênero Astronium (Anacardiaceae), que reúne espécies como Astronium fraxinifolium, Astronium graveolens e Astronium urundeuva, com propriedades anti-inflamatória, antiulcerogênica, cicatrizante e antimicrobiana. Nesse contexto, a inclusão da tecnologia no aprimoramento de plantas medicinais deve ser estimulada já que a estratégia de incorporação de extratos vegetais em sistemas nanoestruturados tem otimizado suas propriedades. A atividade antimicrobiana dos extratos incorporados ou não em sistemas nanoestruturados foi avaliada pela técnica de microdiluição frente aos micro-organismos Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Salmonella setubal (ATCC 19196), Helicobacter pylori (ATCC 43504) e Candida albicans (ATCC 18804). Os extratos vegetais foram testados nas concentrações de 1000 a 7,81 μg/mL e como controle foram utilizados a amoxicilina (100 μg/mL) para H. pylori; a ampicilina (50 μg/mL) para as demais bactérias, e a anfotericina B (32 μg/mL) e fluconazol (256 μg/mL) para C. albicans. Após incubação a 37 ºC/72 horas sob condição de microaerofilia para H. pylori; 37 ºC/24 horas para as demais bactérias e 37 ºC/48 horas para a levedura, foram realizadas as leituras espectrofotométrica e visual, com os reveladores resazurina 0,01% (bactérias), e cloreto de 2,3,5-trifeniltetrazólio 2% - TTC (levedura) para a determinação da concentração inibitória mínima (CIM). A incorporação foi feita em um sistema nanoestruturado constituído por 10%... / Abstract: Herbal medicines have shown amazing results for the treatment of chronic diseases, especially the ones of the digestive tract (gastric and duodenal ulcers, ulcerative colitis and Crohn's disease), diabetes and cancer. The National Policy of Medicinal Plants and Herbal Medicines (Ministry of Health) proposes the study of several plant species, including plants containing the genus Astronium (Anacardiaceae) that includes species such as A. fraxinifolium, A. graveolens and A. urundeuva, which comprise anti-inflammatory, anti-ulcerogenic, healing and antimicrobial properties. In this context, the inclusion of technology in the improvement of medicinal plants should be encouraged since the strategy to incorporate plant extracts in nanostructured systems has optimized their properties. The antimicrobial activity of the extracts, which were incorporated or not into nanostructured systems, was evaluated by microdilution technique for the microorganisms Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Salmonella setubal (ATCC 19196), Helicobacter pylori (ATCC 43504) and Candida albicans (ATCC 18804). The plant extracts were tested at concentrations from 1000 to 7.81 μg/mL, and the following medications were used to check in order to see if they will work with each type of microorganisms: amoxicillin (100 μg/mL) for H. pylori; ampicillin (50 μg/mL) for the other bacteria, amphotericin B (32 μg/mL) and fluconazole (256 μg/mL) for C. albicans. After the incubation at 37 ºC/72 hours under microaerophilic condition for H. pylori; 37 ºC/24 hours for the other bacteria and 37 °C/48 hours for the yeast, spectrophotometric and visual readings were performed, with the developers 0.01% resazurin (bacteria) and 2% 2,3,5-triphenyltetrazolium chloride in order to determine the minimum inhibitory concentration (MIC). The incorporation was prepared into a nanostructured system com... / Mestre

The mupirocin biosynthetic pathway belongs to the trans-AT group in which acyltransferase (AT) activity is provided by a separate polypeptide (MmpC) rather than in cis as found in the typical type I polyketide synthases. AT docking domains have been documented in trans-AT PKS clusters for ten years yet little functional evidence is available. The cluster shows many interesting features that must be understood to create novel products. Specificity studies demonstrated that AT2 performs the typical AT function of loading malonyl-CoA to ACPs throughout the cluster. Mutagenesis studies demonstrated the importance of AT active site residues for protein structural integrity, acquisition and transfer of malonate and propose an alternate role for AT1 as a proofreading enzyme responsible for hydrolysing truncated intermediates from the pathway. Consequently an edit, reload, reduce model for MmpC is proposed. Mutagenesis of docking domains led to a halt in mupirocin production and suggested that docking domains are required for structural integrity of the Mmps or for guiding the ACPs into the correct position for interactions with their respective partners. Studies involving a mutated ACP3 protein confirmed the importance of Trp55, as demonstrated by structural changes and the inability of the protein to accept malonate from AT2.

Graphene oxide (GO) and reduced GO (r-GO) nanomaterials exhibit great potential for several biomedical applications. Of foremost importance is to determine any potential health hazards related in their exposure. In this research, we hypothesised that the different material properties evidenced by GO and r-GO would elicit different biological responses. The first objective of this work was to synthesize Go and r-GO and characterize their physiochemical properties. The second aim was to investigate whether the two-distinct surface chemistries of GO and r-GO influenced their biological effect. The potential toxicity of these nanomaterials was investigated using the normal lung fibroplast cell line MRC-5 and cancerous epithelial lung cell line A549. The cytotoxicity of graphene derivatives was concentration-, time- and cell-dependent and varied according to the material used. Thus, the surface chemistry of graphene plays a critical role in its biocompatibility. Non-cancerous cells had a higher sensitivity to GO cytotoxicity than cancer cells. R-GO was highly biocompatible to MRC-5 cells and for A549 cells had a minimal effect of cell viability. At 37C˚, GO and r-GO were moderately hemolyric at concentration of 125 µg/ml and highly haemolytic at concentration of 300 µg/ml. Exposure of cells to both graphene derivatives led to reactive oxygen species (RO5) generation without genotoxicity. GO, but not r-GO, led to autophagy in both cell lines, possibly inhibiting the PIP3-Akt/mTOR pathway. For both cell lines and at non-lethal concentrations, GO downregulated the expression of glycogen synthase kinase-3 (GSK-3ß). GO was also found to dysregulate both Wnt/b-catenin and Akt cell signalling pathways which are vital for cellular function. The finding relating to cell signalling provide an insight to the safety of GO which is important to its use in cancer therapy.

Hepatitis C virus (HCV) is a major cause of chronic liver disease, leading to hepatic steatosis, fibrosis, cirrhosis and hepatocellular carcinoma. A vaccine is currently not available, while the standard of care is effective in only 50% of treated patients. The first specific anti-HCV drugs have been recently approved, and new classes of targeted agents are under clinical trials/investigation. Nevertheless, improved treatment strategies are needed, in order to bypass the rapid emergence of resistance. All the viral non-structural proteins are a possible target for the identification of novel and selective antivirals. Among them, the NS3 helicase is still underexploited, with no known inhibitor under pre-clinical or clinical development. This enzyme plays a crucial role in the virus life cycle: it catalyses the separation of double-stranded RNA strands, which is necessary for genome amplification and translation. Due to its essential function, the NS3 helicase was chosen as a target for the identification of new, specific anti-HCV compounds. Different computer-aided techniques were employed to identify potential smallmolecule inhibitors of the enzyme. Two structure-based virtual screenings of commercially available compounds were performed on the main nucleic acid binding site. A series of candidate inhibitors was evaluated in the HCV replicon assay, yielding two primary hits with low μM activity. Secondly, the model of the one known inhibitor co-crystallised with the enzyme was used as a starting point for a shape-comparison screening of small molecule libraries. A new series of compounds was selected and evaluated for anti-HCV activity, and one of them was found to inhibit the viral replication at a low μM concentration. Several new derivatives of the initial hits were synthesised, belonging to four main structural families: bis-aromatic piperazine derivatives, symmetrical phenylendiamine compounds, differently substituted thieno-pyrimidines, and triphenyl-pyrrolone analogues. Inhibition of HCV replication in the replicon assay was evaluated for the new compounds prepared and several structures showed a range of activity from low-μM to nM.

The successful clinical translation of non-viral gene delivery systems has yet to be achieved due to the biological and technical obstacles to preparing a safe, potent and cost-effective vector. Hyperbranched polymers have emerged as promising candidates to address gene delivery barriers owing to their relatively simple synthesis and ease of modification compared to other polymers, which makes them more feasible for scale up and manufacturing. In the first part of this thesis, we compare hyperbranched poly(amino acids) synthesised by co-polymerising histidine and lysine, with hyperbranched polylysine prepared using the well-known 'ultra-facile' thermal polycondensation route, to investigate the effects of histidine units on the structure and gene delivery applications of the resultant materials. The conditions of polymerisation were optimised to afford water-soluble hyperbranched polylysine-co-histidine of three different molar ratios with molecular masses varying from 13-30 kDa. Spectroscopic, rheological and thermal analysis indicated that the incorporation of histidine modulated the structure of hyperbranched polylysine to produce a more dendritic polymer with less flexible branches. Experiments to probe gene delivery to A549 and H1299 cells, surprisingly, indicated that the co-polymers containing histidine were not more effective in transfecting a luciferase gene than hyperbranched polylysines synthesised as established literature comparators. We attribute the variations in gene delivery efficacy to the changes induced in polymer architecture by the branching points at histidine residues, and obtain structure-function information relating histidine content with polymer Tg, pKa and ability to form stable polyplexes with plasmid DNA. These results are of significance to nanomedicine design as they indicate that addition of histidine as a co-monomer in the synthetic route to hyperbranched polymers changes not only the buffering capacity of the polymer but has significant effects on the overall structure, architecture and gene delivery efficacy. It has become known that many cationic polymers are cytotoxic and although a large number of polycations have now designed to address the toxicity problem, there is still a practical need to develop a fast and reliable method for assessing the safety of these materials. In this regard, metabolomics provides a high throughput and comprehensive method that can assess the potential toxicity at the cellular and molecular level. Therefore, in the second part of this thesis, metabolomics was applied to investigate the impact of hyperbranched polylysine, hyperbranched polylysine-co-histidine and branched polyethylenimine polyplexes, on the metabolic pathways of A459 and H1299 cell lines. The study revealed that the polyplexes downregulated metabolites associated with glycolysis and the TCA cycle, and induced oxidative stress in both cell lines. The fold changes of the metabolites indicated that the polyplexes of polyethylenimine and hyperbranched polylysine affected the metabolism much more than the polyplexes of hyperbranched polylysine-co-histidine. This was in line with transfection results, suggesting a correlation between the toxicity and transfection efficiency of these polyplexes. This part highlights the importance of metabolomics approaches not just to assess the potential toxicity of polyplexes but also to understand the molecular mechanisms underlying their action, which could help to design more efficient vectors. In the third part of this thesis, we investigated the ability of the hyperbranched polymers to condense and deliver siRNA. The results indicated that the higher molecular mass polymers achieved better siRNA delivery and gene silencing than the lower molecular mass form of the polymers and the lysine-only polymer was more efficient than the histidinylated one. These results can be attributed to the low charge (molecular mass) and stiffness of siRNA molecules in comparison with plasmid DNA, which in combination with the impact of histidine incorporation on the structure of the hyperbranched polymers can also explain the lower efficiency of histidinylated polymers. Overall, this thesis is highlighted the impacts of structural factors on the gene delivery applications of hyperbranched polymers and the importance of these factors to inform the design of new polymeric vectors. Also, metabolomics approaches were introduced to this area, not only to evaluate the safety of gene vectors but also to understand the molecular basis by which these vectors act. The data together suggest that the hyperbranched polymers prepared during thermal polycondensation of amino acids have some efficacy in preliminary gene delivery applications, and that these might be improved with future studies to be a candidate for clinical purposes.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Parkinsons disease (PD) is the second most common neurodegenerative disease after Alzheimers disease, affecting nearly 1% of people above 65 years of age. The major clinical symptoms of this disease are: resting tremor, bradykinesia, rigidity, postural instability and a positive response to dopamine replacement therapy. Pathological findings include selective degeneration of dopaminergic neurons within the substantia nigra, with proteinaceous Lewy body inclusions in surviving cells. The pathogenesis of PD is not yet completely understood, however, both genetic and environmental factors contribute to the disease phenotype. Mutations in the leucine-rich repeat kinase 2 gene (LRRK2; OMIM 609007) represent the most frequent genetic known cause of familial and sporadic PD. The LRRK2 gene encodes a protein, member of the ROCO protein family, that contains both GTPase (ROC) domain and kinase (MAPKKK) domain, as well as, other motifs. In this study, we have screened the main domains of the LRRK2 in a group of 204 PD Brazilian patients. The screening was performed by direct sequencing of the PCR products. By the analysis of 14 exons corresponding to ROC, COR and MAPKKK domains, we identified 31 sequence variations. The novel variants, p.C1770R and p.C2139S, may play a role in the PD pathogenesis. Three exonic alterations (p.R1398R, p.T1410M and p.Y2189C) and nine intronic variants (c.4317+16C>T, c.5317+59A>C, c.5509+20A>C, c.5509+52T>C, c.5509+122A>G, c.5657-46C>T, c.6382-36G>A, c.6382-37C>T and c.6576+44T>C) seem to be not pathogenic. A total of 17 exonic and intronic alterations were previously described in the literature as non-pathogenic polymorphisms (p.R1398H, p.K1423K, p.R1514Q, p.P1542S, c.4828-31T>C, p.G1624G, p.K1637K, p.M1646T, p.S1647T, c.5015+32A>G, c.5170+23T>A, c.5317+32C>T, p.G1819G, c.5948+48C>T, p.N2081D, p.E2108E and c.6381+30A>G). The frequency of pathogenic mutations or potentially pathogenic variants was 3.4% (including the p.G2019S mutation, previously described in our previous report: Pimentel et al., 2008; Abdalla-Carvalho et al., 2010). In familial cases (11.1%) this frequency was approximately six times higher than in sporadic cases (1.8%). Our results suggest that LRRK2 mutations have an important contribution to PD development among Brazilian population. / A doença de Parkinson (DP) é a segunda doença neurodegenerativa mais frequente depois da Doença de Alzheimer, afetando aproximadamente 1% da população com idade superior a 65 anos. Clinicamente, esta doença caracteriza-se pela presença de tremor em repouso, bradicinesia, rigidez muscular e instabilidade postural, os quais podem ser controlados com a administração do levodopa. As características patológicas da DP incluem a despigmentação da substância nigra devido à perda dos neurônios dopaminérgicos e a presença de inclusões proteicas denominadas corpos de Lewy nos neurônios sobreviventes. As vias moleculares envolvidas com esta patologia ainda são obscuras, porém a DP é uma doença complexa, resultante da interação entre fatores ambientais e causas genéticas. Mutações no gene leucine-rich repeat kinase 2 (LRRK2; OMIM 609007) constituem a forma mais comum de DP. Este gene codifica uma proteína, membro da família de proteínas ROCO, que possui, entre outros domínios, dois domínios funcionais GTPase (ROC) e quinase (MAPKKK). Neste estudo, os principais domínios do gene LRRK2 foram analisados em 204 pacientes brasileiros com DP por meio de sequenciamento dos produtos da PCR. Através da análise de 14 exons correspondentes aos domínios ROC, COR e MAPKKK foram identificadas 31 variantes. As alterações novas, p.C1770R e p.C2139S, possuem um potencial papel na etiologia da DP. Três alterações exônicas (p.R1398R, p.T1410M e p.Y2189C) e nove intrônicas (c.4317+16C>T, c.5317+59A>C, c.5509+20A>C, c.5509+52T>C, c.5509+122A>G, c.5657-46C>T, c.6382-36G>A, c.6382-37C>T e c.6576+44T>C) são potencialmente não patogênicas. Ao todo, dezessete variantes exônicas e intrônicas constituem polimorfismos já relatados na literatura (p.R1398H, p.K1423K, p.R1514Q, p.P1542S, c.4828-31T>C, p.G1624G, p.K1637K, p.M1646T, p.S1647T, c.5015+32A>G, c.5170+23T>A, c.5317+32C>T, p.G1819G, c.5948+48C>T, p.N2081D, p.E2108E e c.6381+30A>G). A frequência total de alterações potencialmente patogênicas ou patogênicas detectadas em nossa amostra foi de 3,4% (incluindo a mutação p.G2019S, anteriormente descrita em 2 artigos publicados por nosso grupo: Pimentel et al., 2008; Abdalla-Carvalho et al., 2010), sendo a frequência de mutações nos casos familiares (11,1%) cerca de seis vezes maior do que a encontrada nos casos isolados da DP (1,8%). Os resultados alcançados neste estudo revelam que mutações no gene LRRK2 desempenham um papel significativo como fator genético para o desenvolvimento da DP em pacientes brasileiros.