Dissertations / Theses: 'Lead Candidate'

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Wang, Yunzhi (Yunzhi Diana). "Static corrosion of candidate alloys for the lead-bismuth fast reactor." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45266.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.
Includes bibliographical references (leaves 41-42).
This project examined the corrosion rates and mechanisms of two candidate alloys for use in Lead-bismuth Eutectic (LBE) cooled fast nuclear reactors. The two alloys examined were T91 and Fe-12Cr-2Si. An experimental study was performed to analyze the static corrosion on the two alloys. For the experiment, the polished samples of the two alloys were heated in LBE for 166 hours at 700 The heating conditions, such as temperature, oxygen levels, and moisture levels were monitored closely throughout the duration of the experiment. During the heating process, hydrogen gas was bubbled into the LBE, creating a highly reducing environment. Argon was used as a cover gas. Upon removal from the furnace, the alloy samples were examined via optical microscopy, scanning electron microscopy, and X-ray diffraction analysis. Examination of the samples found no observable corrosion effects on the Fe-12Cr-2Si samples and a thin layer of magnetite on the T91 sample.
by Yunzhi (Diana) Wang.
S.B.

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Kunkle, Jamie Motta A. T. "Structure of oxide layers formed on candidate steel alloys exposed to flowing lead-bismuth eutectic for Generation IV reactor applications." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-3462/index.html.

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Sandhaus, Shayna. "Drug Candidate Discovery: Targeting Bacterial Topoisomerase I Enzymes for Novel Antibiotic Leads." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3561.

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Multi-drug resistance in bacterial pathogens has become a global health crisis. Each year, millions of people worldwide are infected with bacterial strains that are resistant to currently available antibiotics. Diseases such as tuberculosis, pneumonia, and gonorrhea have become increasingly more difficult to treat. It is essential that novel drugs and cellular targets be identified in order to treat this resistance. Bacterial topoisomerase IA is a novel drug target that is essential for cellular growth. As it has never been targeted by existing antibiotics, it is an attractive target. Topoisomerase IA is responsible for relieving torsional strain on DNA by relaxing supercoiled DNA following processes such as replication and transcription. The aim of this study is to find novel compounds that can be developed as leads for antibiotics targeting bacterial type IA topoisomerase. Various approaches were used in order to screen thousands of compounds against bacterial type IA topoisomerases, including mixture-based screening and virtual screening. In the mixture-based screen, scaffold mixtures were tested against the M. tuberculosis topoisomerase I enzyme and subsequently optimized for maximum potency and selectivity. The optimized compounds were effective at inhibiting the enzyme at low micromolar concentrations, as well as killing the tuberculosis bacteria. In a virtual screen, libraries with hundreds of thousands of compounds were screened against the E. coli and M. tuberculosis topoisomerase I crystal structures in order to find new classes of drugs. The top hits were effective at inhibiting the enzymes, as well as preventing the growth of M. smegmatis cells in the presence of efflux pump inhibitors. Organometallic complexes containing Cu(II) or Co(III) were tested as well against various topoisomerases in order to determine their selectivity. We discovered a poison for human type II topoisomerase that has utility as an anticancer agent, as it killed even very resistant cell lines of breast and colon cancer. The Co(III) complexes were found to inhibit the bacterial topoisomerase I very selectively over other topoisomerases. The various methods of drug discovery utilized here have been successful at identifying new classes of compounds that may be further developed into antibiotic drugs that specifically target bacterial type IA topoisomerases.

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Lizzi, Federica <1981&gt. "Drug Discovery for Neglected Tropical Diseases: Design and Synthesis of Lead Candidates for the Treatment of Trypanosomatid Diseases." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2942/.

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Mpamhanga, Chidochangu P. "Development and implementation of a virtual screening strategy for the discovery of CJD lead candidates and their biological evaluation." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444256.

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Alves, Fernanda [UNESP]. "Estudo in vivo dos efeitos da terapia fotodinâmica, mediada pelo Photothazine® e luz led, sobre Cândida Albicans resistente a Fluconazol." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/97271.

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Este estudo avaliou os efeitos da Terapia Fotodinâmica (PDT), mediada pelo Photodithazine® (PDZ) e luz LED, sobre Candida albicans resistente a fluconazol em um modelo de candidose oral induzida. Para isso, camundongos fêmeas de 6 semanas foram imunussuprimidos e inoculados com C. albicans (107 células/mL). Em seguida, aplicou-se 100 mg/L de PDZ (diluído em salina ou hidrogel) na cavidade bucal por 20 min e o dorso lingual foi iluminado (37,5 J/cm² dose de luz). Animais adicionais foram tratados somente com LED ou PDZ. O grupo controle positivo não recebeu nenhum tratamento e, adicionalmente, animais saudáveis receberam tratamento com PDT (n=5). Em seguida, foi feita a recuperação do micro-organismo da língua dos animais. O número de colônias viáveis foi quantificado e os valores de UFC/mL foram determinados. Os animais foram sacrificados e as línguas foram removidas cirurgicamente para análise histológica. Duas colônias de cada animal foram isoladas da placa de cultura para avaliação dos fatores de virulência: adesão e formação de biofilme em superfície abiótica, formas filamentares de crescimento e produção de exoenzimas. Os dados foram analizados por ANOVA (P < 0,05). Os resultados demonstraram que a PDT resultou em redução significativa de C. albicans resistente a fluconazol (1,91 e 1,96 log10) em relação ao grupo controle positivo. Somente a aplicação da luz ou PDZ não reduziu a viabilidade celular. A PDT não ocasionou efeitos adversos no tecido lingual dos animais e reduziu apenas a produção de fosfolipase. A PDT foi efetiva na inativação da C. albicans resistente a fluconazol, sem causar efeitos adversos no tecido lingual.
This study evaluated the effects of Photodynamic Therapy (PDT), mediated by Photodithazine® (PDZ) and LED light, on fluconazole-resistant Candida albicans in a murine model of oral candidosis. For this, six-week-old female mice were immunosuppressed and inoculated with C. albicans (107 células/mL). Then, 100 mg/L of PDZ (diluted in saline or hydrogel) was applied on the oral cavity for 20 min and the dorsum of the tongue was illuminated (37.5 J/cm2 of fluence). The use of PDZ or light only was also investigated. Additionally, healthy animals received treatment with PDT. Positive control animals did not receive any treatment and negative control animals were not inoculated (n=5). After treatment the dorsum of the tongue was swabbed to recover C. albicans. The yeast colony counts were quantified and the number of CFU/mL was determined. The animals were killed and the tongues were surgically removed for histological analysis. Two yeast colony of each group were isolated from the culture plate for the evaluation of virulence factors: adhesion and biofilm formation in abiotic surface, filamentous forms of growth and production of exoenzymes. Data were analyzed by ANOVA (P < 0.05). PDT resulted in a significant reduction of fluconazole-resistant C. albicans (1.91 e 1.96 log10). The application of PDZ or LED only did not reduce the cell viability. PDT did not cause adverse effects in the local mucosa and it was able to reduce only phospholipase production. PDT was effective in the inactivation of fluconazole-resistant C. albicans without harming the tongue tissue.

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Alves, Fernanda. "Estudo in vivo dos efeitos da terapia fotodinâmica, mediada pelo Photothazine® e luz led, sobre Cândida Albicans resistente a Fluconazol /." Araraquara : [s.n.], 2013. http://hdl.handle.net/11449/97271.

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Orientador: Ana Claúdia Pavarina
Banca: Gilberto Ubida Leite Braga
Banca: Ewerton Garcia de Oliveira Mima
Resumo: Este estudo avaliou os efeitos da Terapia Fotodinâmica (PDT), mediada pelo Photodithazine® (PDZ) e luz LED, sobre Candida albicans resistente a fluconazol em um modelo de candidose oral induzida. Para isso, camundongos fêmeas de 6 semanas foram imunussuprimidos e inoculados com C. albicans (107 células/mL). Em seguida, aplicou-se 100 mg/L de PDZ (diluído em salina ou hidrogel) na cavidade bucal por 20 min e o dorso lingual foi iluminado (37,5 J/cm² dose de luz). Animais adicionais foram tratados somente com LED ou PDZ. O grupo controle positivo não recebeu nenhum tratamento e, adicionalmente, animais saudáveis receberam tratamento com PDT (n=5). Em seguida, foi feita a recuperação do micro-organismo da língua dos animais. O número de colônias viáveis foi quantificado e os valores de UFC/mL foram determinados. Os animais foram sacrificados e as línguas foram removidas cirurgicamente para análise histológica. Duas colônias de cada animal foram isoladas da placa de cultura para avaliação dos fatores de virulência: adesão e formação de biofilme em superfície abiótica, formas filamentares de crescimento e produção de exoenzimas. Os dados foram analizados por ANOVA (P < 0,05). Os resultados demonstraram que a PDT resultou em redução significativa de C. albicans resistente a fluconazol (1,91 e 1,96 log10) em relação ao grupo controle positivo. Somente a aplicação da luz ou PDZ não reduziu a viabilidade celular. A PDT não ocasionou efeitos adversos no tecido lingual dos animais e reduziu apenas a produção de fosfolipase. A PDT foi efetiva na inativação da C. albicans resistente a fluconazol, sem causar efeitos adversos no tecido lingual.
Abstract: This study evaluated the effects of Photodynamic Therapy (PDT), mediated by Photodithazine® (PDZ) and LED light, on fluconazole-resistant Candida albicans in a murine model of oral candidosis. For this, six-week-old female mice were immunosuppressed and inoculated with C. albicans (107 células/mL). Then, 100 mg/L of PDZ (diluted in saline or hydrogel) was applied on the oral cavity for 20 min and the dorsum of the tongue was illuminated (37.5 J/cm2 of fluence). The use of PDZ or light only was also investigated. Additionally, healthy animals received treatment with PDT. Positive control animals did not receive any treatment and negative control animals were not inoculated (n=5). After treatment the dorsum of the tongue was swabbed to recover C. albicans. The yeast colony counts were quantified and the number of CFU/mL was determined. The animals were killed and the tongues were surgically removed for histological analysis. Two yeast colony of each group were isolated from the culture plate for the evaluation of virulence factors: adhesion and biofilm formation in abiotic surface, filamentous forms of growth and production of exoenzymes. Data were analyzed by ANOVA (P < 0.05). PDT resulted in a significant reduction of fluconazole-resistant C. albicans (1.91 e 1.96 log10). The application of PDZ or LED only did not reduce the cell viability. PDT did not cause adverse effects in the local mucosa and it was able to reduce only phospholipase production. PDT was effective in the inactivation of fluconazole-resistant C. albicans without harming the tongue tissue.
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Luz, Felipe Brunatto da. "Aplicação de Terapia Fotodinâmica (PDT) usando luz LED azul sobre culturas de Candida albicans - in vitro." Universidade Federal de Pelotas, 2014. http://repositorio.ufpel.edu.br:8080/handle/prefix/3471.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
O fungo Candida albicans é frequentemente encontrado como componente da microbiota da cavidade oral, sendo agente etiológico da candidíase eritematosa crônica (estomatite por dentadura). Condição esta, uma infecção oportunista, de caráter crônico que acomete grande parte dos usuários de próteses. O tratamento tradicional com antifúngicos, muitas vezes é duradouro, colaborando para o surgimento de cepas resistentes desse fungo. Assim sendo, torna-se necessária uma alternativa de tratamento efetiva contra a candidíase oral e que não apresente efeitos colaterais. O objetivo desse estudo foi desenvolver um novo dispositivo a partir de um fotopolimerizador odontológico, baseado na tecnologia LED com emissão de luz azul. Além disso, verificar a ação da PDT com azul de metileno associada ao uso dessa fonte sobre culturas de Candida albicans. Após o crescimento e identificação das colônias foram selecionadas 04 cepas de Candida albicans e 01 cepa ATCC (62342) e realizadas diluições obedecendo-se a escala 0,5 de Macfarland (1x108 UFC). Desse inóculo, foram colocados 100 µl em cada poço de uma placa de microtitulação de 96 poços. As amostras das colônias de Candida albicans foram distribuídas em triplicata nas placas de cultura. No grupo testado foram colocados 90 µl de PBS, adicionado a 10 µl de azul de metileno. As placas foram incubadas durante 30 minutos e, após esse período, foi realizada a irradiação com LED azul. Para realizar a PDT a placa foi dividida em 6 setores de dimensões iguais. Cada setor foi irradiado durante 6 minutos na dosimetria de 122 J/cm2, potência de 260 mW e comprimento de onda de 455 nm em aplicação única, totalizando 36 minutos de aplicação em cada placa. Após esse desafio, foram realizadas diluições seriadas 1:10 em 4 alíquotas sucessivas. Dessa diluição foram semeados 25 µl em placas de Petri e incubadas a 37ºC por 48 horas. Após esse período foram feitas as contagens das colônias por dois examinadores previamente treinados e calibrados. Os resultados foram analisados estatisticamente usando ANOVA seguido por teste de Tukey com 5% de nível de significância e não mostraram diferença estatisticamente significante (p>0,05) entre os diferentes grupos e o grupo controle. Constatando-se que a PDT usando fonte de luz LED é uma alternativa viável, no entanto no presente estudo não foi possível constatar a ação dessa terapia.
The fungus Candida albicans is often found as the microflora of the oral cavity component, as the etiological agent of erythematous candidiasis (denture stomatitis), this condition is an opportunistic infection, a chronic condition that affects most users of prostheses. Traditional treatment with antifungals, often lasting, contributing to the manifestation of resistant strains of this fungus. Therefore, it is necessary effective alternative treatment for oral candidiasis and who does not produce side effects. The aim of this study was to develop a new device from a dental curing light, based on the LED technology with blue light emission. As well, check the action of PDT with methylene blue associated with the use of this source on cultures of Candida albicans. After the growth and identification of colonies were selected 04 strains of Candida albicans and 01strain ATCC (62342) and made dilutions obeying the scale of 0.5 Macfarland (1x108 CFU). In this inoculum, 100 mL were placed in each well of a 96-well microtiter plate wells. Samples of colonies of Candida albicans were triplicate distributed in culture plates. On the test group 90 µl of PBS, added to 10 µl of methylene blue were placed. The plates were incubated for 30 minutes and, thereafter, irradiation was performed with blue LED. To perform PDT the plate was divided into 6 sectors of equal dimensions. Each sector was irradiated for 6 minutes dosimetry of 122 J/cm² power of 260 mW and wavelength of 455 nm in a single application, totaling 36 minutes of application on each plate. After this challenge, serial dilutions 1:10 in 4 successive aliquots were performed. This dilution were seeded 25 µl in Petri dishes and incubated at 37 ° C for 48 hours. After this period the numbers of colonies were made by two previously trained and calibrated examiners. The results were statistically analyzed using ANOVA followed by Tukey test at 5% significance level and showed no statistically significant difference (p> 0.05) between the different groups and the control group. The authors verified that PDT using LED light source is a viable alternative, however in this study it was not possible to observe the action of this therapy.

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Oliveira, Lucas Portela. "Síntese, caracterização de fosfato de prata (Ag3PO4) e sua ação contra Candida albicans associado com luz LED /." Araraquara, 2018. http://hdl.handle.net/11449/157070.

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Orientador: Carlos Eduardo Vergani
Resumo: Há diversas possibilidades para o controle microbiano, dentre elas, o uso de microcristais associados à prata (Ag), e a inativação fotodinâmica antimicrobiana (do inglês, aPDI). Devido à capacidade de fotoexcitação no comprimento de onda de luz azul, fosfato de prata (Ag3PO4) foi submetido à exposição a luz em 455nm. Este trabalho teve como objetivo sintetizar, caracterizar e verificar a capacidade fotocatalítica e antimicrobiana dos microcristais de Ag3PO4, utilizando culturas de C. albicans em suspensão e biofilme, na presença e ausência de luz. Os microcristais foram sintetizados pelo método da co-precipitação, e foram determinados o "gap" de energia e o espectro de absorção do material através de análise de espectro de UVVIS. Para caracterizar Ag3PO4, realizou-se a difração de raios-X (DRX), microscopia eletrônica de varredura por emissão de campo (MEV-EC) e atividade fotocatalítica (degradação de rodamina) após 4 exposições à luz. Para os ensaios microbiológicos (UFC/mL), determinou-se a concentração fungicida mínima (CFM) em suspensão e biofilme, na ausência e presença de luz (55,8 J/cm²). Para análise dos resultados, aplicou-se o teste de análise de variância de dois fatores, com teste posterior de Tukey. Os resultados demonstraram que o espectro de absorção abrange a faixa azul do comprimento de onda, apesar do maior sinal estar localizado na região de luz UV. Nos espectros de DRX observou-se a produção de prata cúbica e hexagonal no decorrer das exposições, juntament... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: There are several possibilities for microbial control, among them the use of microcrystals associated with silver (Ag), and antimicrobial photodynamic inactivation (aPDI). Due to the ability of photoexcitation in the blue light wavelength, silver phosphate (Ag3PO4) was subjected to light exposure at 455nm. Thus, the aim was to synthesize, characterize and verify the photocatalytic and antimicrobial capacity of Ag3PO4 microcrystals using cultures of C. albicans in planktonic and biofilm form, in the presence and absence of light. Microcrystals were synthesized by the coprecipitation method, the energy band gap and the absorption spectrum of the material were determined by UV-VIS spectrum analysis. To characterize Ag3PO4, Xray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photocatalytic activity (rhodamine degradation) were performed after 4 exposures to light. For the microbiological tests (CFU/mL), the minimum fungicidal concentration (MFC) in planktonic and biofilm was determined, in the absence and presence of light (55.8 J/cm²). To analyze the results, a two-way analysis of variance (ANOVA) was applied, followed by Tukey post-test. The results showed the absorption spectrum covers the blue wavelength range, although the largest peak is located in the UV light region. The XRD spectra produced cubic and hexagonal silver during the exposures, with an increase of amorphous material. The microcrystal size was observed (0.12 μm) by FE-SEM images, wi... (Complete abstract click electronic access below)
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Geurtz, Lea [Verfasser]. "Speziesverteilung und Resistenzepidemiologie von Candida Spezies aus einer multizentrischen Blutkulturstudie - Evaluierung eines semiautomatisierten Verfahrens (VITEK 2) zur Resistenztestung / Lea Geurtz." Köln : Deutsche Zentralbibliothek für Medizin, 2010. http://d-nb.info/1009194879/34.

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Lima, Gustavo Machado Alvares de. "Estudos estruturais de enzimas da via de biossíntese de folatos de Xanthomonas albilineans para o desenvolvimento de novos candidatos a agroquímicos para a cultura de cana-de-açúcar." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-31012018-164124/.

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O destaque da cana-de-açúcar como fonte de energia renovável tem motivado a busca por melhorias no processo de cultivo e processamento da planta, buscando o aumento da produtividade dos canaviais. Dentre os fatores limitantes para o aumento da produção de cana-de-açúcar, destaca-se a ocorrência de fitodoenças, como por exemplo a escaldadura das folhas, causada pela bactéria Xanthomonas albilineans. Essa doença causa a diminuição do valor energético do caldo extraído da planta, e a ausência de tratamento químico ou biológico acarreta na necessidade de reforma precoce dos canaviais, causando perdas significativas para o agronegócio brasileiro. Portanto, existe uma grande necessidade no desenvolvimento de novas moléculas capazes de atuar como defensivos agrícolas com eficiência e especificidade. Neste trabalho, duas estratégias foram empregadas para a identificação de moléculas como potenciais candidatos a agroquímicos. Na primeira, avaliou-se o potencial inibidor de moléculas de origem natural ou sintética em ensaios fenotípicos contra a cultura de X. albilineans, identificando dois derivados, um de nitrotiofeno e um de nitrofurano, capazes de inibir o crescimento bacteriano. Na segunda estratégia, duas enzimas da via de biossíntese de folatos, 2-amino-4-hidroxi-6-hidroximetil di-hidropterina pirofosfoquinase (XaHPPK) e 7,8-di-hidroneopterina aldolase (XaDHNA), foram selecionadas como alvos moleculares. Métodos em biologia molecular e biologia estrutural foram empregados para a obtenção de proteínas puras e solúveis, visando-se a elucidação das estruturas tridimensionais e caracterização bioquímica dos alvos. Estudos de desnaturação térmica foram conduzidos para determinação da afinidade da XaHPPK pelo substrato natural 7,8-di-hidropterina (Kd = 97 ± 3 µM). Os experimentos de biologia estrutural resultaram na determinação da estrutura da XaHPPK a 2,3 Å de resolução (PDB ID, 5VSP) com o grupo espacial P212121. A obtenção da estrutura a alta resolução permitiu a aplicação de estratégias computacionais para a descoberta de potenciais inibidores. Os estudos da XaDHNA possibilitaram a coleta de um conjunto de dados à 3,5 Å de resolução, no grupo espacial I422. Os experimentos e resultados obtidos neste doutorado ampliam o conhecimento sobre a via de biossíntese de folatos em X. albilineans e abrem o caminho para a descoberta de novos inibidores antibacterianos utilizando técnicas baseadas na estrutura do alvo.
The importance of sugarcane as a source of renewable energy has pushed researchers to search for improvements in the process of cultivation and processing of the plant, looking after increase the productivity of sugarcane crops. Among known facts that limits sugarcane production, we highlight the occurrence of plant diseases, such as leaf scald, a bacterial disease caused by Xanthomonas albilineans. This disease decreases the energetic value of the broth extracted from the cane, and the absence of chemical or biological treatment entails the need for early refresh sugarcane plantations, causing significant losses for Brazilian agribusiness. Therefore, the economic interest in the development of new molecules capable of acting as agricultural defenses with efficiency and specificity is motivating. Acting on the essential biochemical pathways of the pathogen is a recurring strategy in the development of bioactive molecules. Thus, several inhibitor identification strategies were used. Firstly, the inhibitory potential of molecules from natural or synthetic origins were evaluated in phenotypic assays against the culture of X. albilineans, identifying two nitrothiophene and nitrofuran derivatives capable of inhibiting bacterial growth at 2 mM. In another strategy, the essential pathway of X. albilineans for folate biosynthesis was selected and two proteins of this pathway investigated: 2-amino-4-hydroxy-6-hydroxymethyl dihydropteridine pyrophosphokinase (XaHPPK) and 7,8-dihydroneopterin aldolase (XaDHNA). Both molecular biology and structural biology methods were used to obtain pure and soluble proteins, aiming the obtaining of three-dimensional structures and biochemical characterization of targets. Studies with the XaHPPK protein for kinetic characterization made possible to calculate the Kd apparent (Kd = 97 ± 3 μM) for the substrate 7,8-dihydropterin. Structural biology experiments resulted in a 2.3 Å resolution structure in the space group P212121, available in the PDB under the 5VSP identifier. Structure based drug design for XaHPPK structure, SBDD, were performed using ZINC15 database with hierarchical filters and the Glide docking software. The XaDHNA studies enabled the collection of a set of data at 3.5 Å resolution in the space group I422. The experiments and results obtained in this doctorate increase the knowledge about the folate biosynthesis pathway in X. albilineans and open the way for the discovery of new antibacterial inhibitors using structure based drug design.

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Bueno, Renata Vieira. "Estudos estruturais e funcionais da enzima N5, N10 - metilenotetrahidrofolato-desidrogenase-ciclohidrolase de Xanthomonas albilineans aplicados à descoberta de candidatos a inibidores para o tratamento da escaldadura das folhas." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-06062018-092525/.

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A escaldadura das folhas, causada pela bactéria Gram-negativa Xanthomonas albilineans, é uma das doenças mais importantes que afetam o cultivo da cana-de-açúcar, causando significativa diminuição da produtividade, necessidade de reforma precoce dos canaviais e queda da qualidade do caldo extraído. O impacto dessa doença somado à ausência de agentes químicos ou biológicos para o controle estimula a pesquisa para a descoberta e desenvolvimento de moléculas bioativas como candidatos a novos defensivos agrícolas. Nesse contexto, a enzima N5, N10-metilenotetrahidrofolato desidrogenase ciclohidrolase (FolD) destaca-se como potencial alvo molecular. O projeto de doutoramento visou a caracterização estrutural e funcional da FolD de X. albilineans (XaFolD), além da triagem de moléculas candidatas a inibidores. Para tanto, foram conduzidos estudos integrados em biologia molecular estrutural e química biológica. A expressão heteróloga e purificação da XaFolD resultaram na produção de proteína funcional e adequada aos ensaios de cristalização. A caracterização das atividades desidrogenase e ciclohidrolase da XaFolD indicou os valores de KM para os substratos de ambas as reações, N5, N10-metileno-tetrahidrofolato (50 ± 10 µM) e N5, N10-metenil-tetrahidrofolato (32 ± 3 µM) e do cofator NADP+ (688 ± 81 µM). A estrutura da XaFolD na forma apo, elucidada a 2,1 Å de resolução, revelou uma proteína constituída por 11 hélices alfa e 9 fitas beta distribuídas em um domínio N-terminal catalítico e um domínio C-terminal de ligação ao dinucleotídeo. A enzima pura foi utilizada para a triagem de 1.124 fragmentos por interferometria de biocamada (BLI) e foram identificados três ligantes, DDD00808259 (KD = 260 μM), DDD01305586 (KD = 3 mM) e DDD00100784 (KD = 210 μM), com valores de afinidade na faixa do submilimolar até baixo milimolar. Paralelamente, uma abordagem computacional foi empregada para a triagem virtual de base de dados de compostos como candidatos a ligantes da XaFolD. Os critérios utilizados resultaram na seleção e aquisição de 31 compostos de diferentes classes químicas para avaliação da atividade inibitória frente a enzima alvo. Por fim, ensaios fenotípicos de triagem de inibidores resultaram na descoberta de compostos capazes de inibir o crescimento in vitro de X. albilineans. Dentre os inibidores identificados o composto THP2 apresentou a maior potência, com valor determinado de EC50 igual a 23 ± 2 μM. Os dados estruturais, cinéticos e biofísicos obtidos nesta tese de doutoramento formam a base experimental e computacional para a descoberta e planejamento de inibidores candidatos a novos agroquímicos para o tratamento da escaldadura das folhas.
The leaf scald disease is a severe condition which affects sugarcane crops. Leaf scald is caused by the Gram-negative bacteria Xanthomonas albilineans and it has a dramatic impact on crop productivity, including the yield reduction and dropping the quality of the juice. The impact of this disease besides the absence of chemical or biological agents to treat it stimulates the research towards the discovery and development of bioactive molecules as lead candidates to new agrochemicals. In this context, the enzyme N5, N10-methylenetetrahydrofolate dehydrogenase-cyclohydrolase (XaFolD) stands out as a potential molecular target. Facing this scenario, the PhD project comprised the structural and functional characterization of X. albilineans FolD (XaFolD) and the screening of molecules to identify inhibitors. For this purpose, integrated studies in structural molecular biology and biological chemistry have been carried out. Suitable protein for crystallization and kinetic assays was produced by heterologous expression. The XaFolD dehydrogenase and cyclohydrolase activities were characterized, revealing KM values of 50 ± 10 µM for N5, N10- methylenetetrahydrofolate, 32 ± 3 µM for N5, N10-methenyltetrahydrofolate, and 688 ± 81 µM for NADP+. The structure of XaFolD in the apo form was elucidated at 2.1 Å resolution and it revealed a protein consisting of 11 alpha helices and 9 beta sheets distributed in the catalytic N-terminal domain and the C-terminal dinucleotide binding domain. Screening of 1,124 fragments by biolayer interferometry (BLI) revealed three ligands, DDD00808259, DDD01305586 and DDD00100784, with determined KD values of 260 µM, 3 mM and 210 M, respectively. Furthermore, a virtual screening was performed to identify XaFolD ligands. As a result, 31 chemically diverse compounds were selected to be evaluated by potency assays. Additionally, phenotypical assays against X. albilineans have been performed and inhibitors were identified. Among them, the compound THP2 presented the highest potency, with a determined value of EC50 equal to 23 ± 2 µM. The structural, kinetic, and biophysical data obtained in this PhD thesis provide the molecular basis for discovering and planning bioactive molecules as agrochemicals to control leaf scald disease.

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Alves, Orley Araújo. "Avaliação da eficiência do diodo emissor de luz (LED) emitindo em 460 nm associado à curcumina na fotossensibilização letal de Candida albicans e de Aggregatibacter actinomycetemcomitans: Estudo in vitro." Universidade Federal de Minas Gerais, 2011. http://hdl.handle.net/1843/BUOS-8NWGAV.

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A terapia fotodinâmica antimicrobiana consiste em uma promissora técnica a ser utilizada como coadjuvante no tratamento de infecções orais. O tratamento se baseia na administração tópica de um fotossensibilizador que se acumula nas células microbianas, e na presença de luz de comprimento de onda adequado e oxigênio, promove reações fotoquímicas produzindo espécies químicas que levam a sensibilização letal dos microrganismos. Atualmente, na maioria dos consultórios odontológicos existem aparelhos emissores de luz que podem ser de dois tipos; aqueles que utilizam como fonte de luz uma lâmpada halógena, e os que empregam diodos emissores de luz (LEDs) também como fonte de luz azul. Estes aparelhos são normalmente utilizados para fotopolimerização de resinas compostas ou acelerar o processo de clareamento dental, e também utilizado na terapia fotodinâmica na inativação de microrganismos, inclíndo vários presentes naturalmente na cavidade oral. A Curcumina, conhecida como Açafrão da índia (Curcuma longa L.) apesar de não ser uma planta nativa do Brasil é amplamente utilizada pelos brasileiros seja na medicina popular, como tempero ou como corante alimentício. A Curcumina, em concentrações específicas, quando irradiada por alguns comprimentos de onda, tem um grande efeito fototóxico em bactérias Gram positivas. Neste trabalho foi analisada a eficiência de um equipamento rotineiramente encontrado nos consultórios odontológicos, o LED azul ( = 450 a 470 nm), associado um corante de origem natural, a Curcumina, por meio do estudo da susceptibilidade in vitro, a inibição fotodinâmica de isolados do fungo Candida albicans e da bactéria Aggregatibacter actinomycetemcomitans. Foram preparadas soluções aquosas de Curcumina com concentrações reduzidas, e verificada a ressonância entre o corante e a luz emitida pelo equipamento testado. Os resultados obtidos demonstraram que o LED azul associado à Curcumina nos parâmetros utilizados possuem eficiência fotodinâmica na inativação dos microrganismos analisados (redução de Log10 6 UFC/ mL), podendo assim fornecer subsídios para o planejamento de nova alternativa para o tratamento das infecções relacionadas a esses agentes.

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Cavallin, Mara. "Physiopathologie moléculaire et cellulaire des anomalies du développement du cortex cérébral : le syndrome d'Aicardi WDR81 mutations cause extreme microcephaly and impair mitotic progression in human fibroblasts and Drosophila neural stem cells TLE1, a key player in neurogenesis, a new candidate gene for autosomal recessive postnatal microcephaly Mutations in TBR1 gene leads to cortical malformations and intellectual disability Aicardi syndrome: Exome, genome and RNA-sequencing of a large cohort of 19 patients failed to detect the genetic cause Recurrent RTTN mutation leading to severe microcephaly, polymicrogyria and growth restriction Recurrent KIF2A mutations are responsible for classic lissencephaly Recurrent KIF5C mutation leading to frontal pachygyria without microcephaly Rare ACTG1 variants in fetal microlissencephaly De novo TUBB2B mutation causes fetal akinesia deformation sequence with microlissencephaly: An unusual presentation of tubulinopathy A novel recurrent LIS1 splice site mutation in classic lissencephaly Further refinement of COL4A1 and COL4A2 related cortical malformations Prenatal and postnatal presentations of corpus callosum agenesis with polymicrogyria caused By EGP5 mutation Delineating FOXG1 syndrome from congenital microcephaly to hyperkinetic encephalopathy Delineating FOXG1 syndrome: From congenital microcephaly to hyperkinetic encephalopathy." Thesis, Sorbonne Paris Cité, 2019. https://wo.app.u-paris.fr/cgi-bin/WebObjects/TheseWeb.woa/wa/show?t=2213&f=18201.

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Les malformations du cortex cérébral (MDC) représentent une cause importante de handicap et d'épilepsie pharmaco-résistante. Le séquençage à haut débit a permis une amélioration considérable de l'identification des bases moléculaires des MDC non syndromiques. Toutefois, certaines formes, notamment les MDC complexes, demeurent inexpliquées. Mon projet de thèse a pour objectif de progresser dans la compréhension des MDC complexes en utilisant deux modèles : les microlissencéphalies (MLIS) et le syndrome d'Aicardi (AIC), une forme syndromique particulière associant des malformations de l'oeil et du cerveau uniquement rapporté chez les filles. L'étude par séquençage d'exome en trios de 16 familles MLIS m'a permis d'identifier et de caractériser un nouveau gène, WDR81, impliqué dans le cycle cellulaire. Par la même stratégie, j'ai pu identifier un variant homozygote pathogène dans TLE1, un partenaire majeur de FOXG1 dans la balance prolifération/différenciation de progéniteurs neuronaux, dans une famille consanguine de microcéphalie postnatale dont le phénotype est proche du syndrome FOXG1. En parallèle, mes travaux ont permis de préciser les spectres phénotypiques associés à RTTN, EPG5, COL4A1, COL4A2, TBR1, KIF5C, KIF2A et FOXG1. La deuxième partie de mon projet avait pour objet l'identification des bases moléculaires du syndrome d'Aicardi à partir d'une cohorte internationale de 19 patientes. Après avoir exclu un biais d'inactivation du chromosome X et la présence de microremaniements chromosomiques, j'ai réalisé un séquençage d'exome en trio. Aucun variant récurrent n'a été retrouvé dans les séquences codantes. Dans un second temps, j'ai testé une approche combinant les données du séquençage de génome et l'analyse du transcriptome (RNA-Seq) sur fibroblastes, me permettant d'identifier des transcrits dérégulés qui étaient impliqués dans le développement du cerveau et de l'oeil. J'ai comparé les résultats de cette analyse avec ceux de l'analyse du génome dans le but d'identifier des variants dans ces gènes candidats. En conclusion, mon travail de thèse a permis d'améliorer la connaissance des bases moléculaires des MDC complexes et d'ouvrir des perspectives de nouveaux mécanismes tels que ceux engageant les gènes WDR81 et EPG5, et le rôle des endosomes et de l'autophagie dans les MDC, et aussi TLE1 comme nouvelle cause de microcéphalies postnatales. Mes travaux ont également permis de générer une collection de données de séquençage haut débit (WES, WGS et RNA-Seq) qui seront mises en commun dans le cadre d'un consortium international afin de développer des nouvelles stratégies d'analyse en particulier pour les séquences non codantes. Cette approche permettra également d'ouvrir la voie vers la compréhension des mécanismes cellulaires impliqués dans la formation du cerveau et de l' œil
Malformations of cortical development (MCD) are a major cause of intellectual disability and drug-resistant epilepsy. Next Generation Sequencing (NGS) has considerably improved the identification of the molecular basis of non-syndromic MCD. However, certain forms, including complex MCD, remain unexplained. My PhD project aimed to improve the understanding of complex MCD using two disorders: Microlissencephaly (MLIS) and Aicardi Syndrome (AIC), the latter associating brain and eye malformations and only reported in girls. Trio Whole Exome Sequencing (WES) performed in 16 MLIS families allowed me to identify and functionally characterize a new MLIS gene, WDR81, in which mutations lead to cell cycle alteration. Moreover, using the same strategy, I was able to identify a pathogenic homozygous variant in TLE1 in a patient from consanguineous family with a postnatal microcephaly, suggestive of a FOXG1-like presentation. Interestingly, TLE1 is a major partner of FOXG1, a gene involved in maintaining the balance between progenitor proliferation and differentiation. In parallel, my work allowed me to redefine the phenotypic spectrum associated with RTTN, EPG5, COL4A1 and COL4A2, TBR1, KIF5C, KIF2A and FOXG1. The second part of my PhD program was aimed at identifying the genetic basis of AIC in an international cohort of 19 patients. After excluding a skewed X chromosome inactivation and the presence of chromosomal rearrangements, I performed WES in trios. The analysis of the data from WES did not allow me to identify any recurrent variants. I therefore tested a new approach combining Whole Genome Sequencing (WGS) and RNA-Sequencing (RNA-Seq) on fibroblast cells. I identified a number of deregulated transcripts implicated in brain and eye development. I compared the results of this analysis with the WGS analysis in order to find variants in these candidate genes. In conclusion, these studies have improved the knowledge of the molecular basis of complex MCD, such as TLE1 in postnatal microcephaly, and revealed the pathogenic mechanisms such as WDR81 in cell cycle progression and EPG5 in endosomes and autophagy. My work has also generated a collection of NGS data (WES, WGS and RNA-Seq) that will be shared in an international consortium to develop new analytical strategies, in particular for the non-coding DNA regions. This novel strategy provides opportunities to improve understanding of the cellular mechanisms involved in brain and eye development

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15

Hähnke, Volker Dirk [Verfasser]. "Text-based similarity searching for hit- and lead-candidate identification / von Volker Dirk Hähnke." 2010. http://d-nb.info/1011435446/34.

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Shaheen, Tanzia. "Screening lead small molecules for cytokine induction in a human whole blood assay informs candidate adjuvant selection." Thesis, 2018. https://hdl.handle.net/2144/31282.

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BACKGROUND: The human immune system is comprised of various cells that function to fight infection while also avoiding harmful inflammatory and autoimmune responses. The immune system consists of the innate and adaptive immune responses. While the adaptive immune response is involved in the late phase of infection and plays a role in generating classic T and B-cell based immunological memory, the innate immune response is the first line of defense and plays a role in early recognition of foreign substances and induction of an inflammatory response. Although the innate immune response is a natural and inborn response, it varies with age. Human newborns in particular are immunologically distinct due to their polarized T helper type 2 (Th2) cell response and increased anti-inflammatory cytokine production. While these adaptations protect the fetus from rejection by the mother, they lead to increased susceptibility of newborns to infection. While immunization is the most promising strategy to combat this increased susceptibility of newborns, the responses of newborns to different vaccines are impaired as a result of their functionally distinct immune system. For this reason, there have been efforts to develop and incorporate adjuvants into vaccines in order to enhance the immune response of newborns and young infants, who suffer the greatest burden of infectious diseases. OBJECTIVE: The objective of this thesis is to determine which compound(s) in a small molecule library (compound 037 family) that had been identified based on a high throughput TNF-α screen of human primary mononuclear cells activates immune cells and has the potential to act as effective vaccine adjuvants. METHODS: Human cord blood was collected from 7 healthy term newborns after Cesarean section and peripheral blood was collected from the arms of 15 healthy adult volunteers between the ages of 18 and 60. The blood was processed and the compounds of the small molecule library were tested via whole blood assays and enzyme-linked immunosorbent assays (ELISAs) to measure production of pro-inflammatory cytokines, specifically tumor necrosis factor (TNF) and interleukin-1β (IL-1β). The responses of the compounds were further characterized by measuring additional cytokines and chemokines via a 41-plex cytokine multiplex assay. RESULTS: It was determined that at the top two concentrations that were tested (3.7 μM and 11.0 μM), certain compounds of the 037 family induced TNF and IL-1β production comparable to that produced by R848, an already established adjuvant. The compounds with the most activity depended on which cytokine was being produced as well as the age group (newborn vs. adult). Results of the 41-plex cytokine multiplex showed that while there is no clear indication of which group of cytokines are produced after stimulation with these compounds, there was increased production of certain chemokines, especially in adults. CONCLUSIONS: The difference in activity of the compounds in the 037 family suggests that the functional groups might play a role in enhancing activity of certain compounds. The increased production of chemokines after stimulation with these compounds suggests that the compounds might activate pathways different from TLR7/8 but still results in an inflammatory response. More work needs to be done in order to identify the receptors and pathways that these compounds activate.

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Po-Chu, Chen, and 陳伯珠. "一.High Throughput Screening of Anti-liver-cancer Drug Candidate from Antrodia Camphorata Mycelia.二.Studies on the Apoptosis Pathway of the Anti-liver-cancer Drug Lead Treated Human Cancer Cell HepG2 at the p53, bax and bcl-2 mRNA Level." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/11880911841117661489.

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碩士
國立中正大學
化學研究所
92
Abstract Antrodia camphorata, “niu-chang-chih”, is a unique species of fungus found in Taiwan . Its fruit body has been used as Chinese herb in treatment of various diseases. Recent in vivo studies have revealed that crude extracts of Antrodia camphorata can improve liver function, increase immunity and inhibit the growth of carcinoma. The objective of this research is to identify bioactive compounds from Antrodia camphorata’s mycelia with pharmaceutical effect on human liver cancer cells. We used high throughput method to screen and search for bioactive substances from the crude extract by employing human liver cancer cell based assay, instead of slow and expensive animal testing. At first, we were pleased to find that, when treating Hep 3B (a human liver cancer cell) with crude extracts of mycelia and fruit body of Antrodia camphorata for 48 hr, the IC50 values of 44.25 and 12.22 μg/mL were obtained, respectively. The crude extract of Antrodia camphorata was further fractionated (two times) on a silica gel column. These separated fractions (twelve fractions in total) were individually treated with Hep 3B cells. We found that the fraction 6 (F6) has salient bioactivity with a significant IC50 value of 6.4614 μg/mL. The active ingredient in F6 was purified by both HPLC and TLC and structurally identified by FAB MS, NMR and IR. The compound identified was 1-hydroxy-3-isobutyl-4-[4-(3-methyl-but-2-enyloxy)-phenyl]-pyrrole-2,5-dione (formula: C19H23NO4; molecular weight: 329.16). In the treatment of both Hep G2 and Hep 3B cells for 48 h, this compound gave the IC50 values of 9.903 and 6.388μg/mL, respectively.

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Valkova, Simona Hristova. "Campaigning as a Spitzenkandidat: are lead candidates aligned with their party's manifesto?" Master's thesis, 2020. http://hdl.handle.net/10071/21031.

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Nowadays, political actors use Twitter as one of the main online tools to campaign and connect to their constituencies, and so do "Spitzenkandidaten". The "Spitzenkandidat" process, which was initially implemented in 2014, is a widely researched topic. However, with campaign personalization, being one of its main drivers, it is surprising to see the lack of literature on the subject specifically connected to the lead candidates in the Twitter sphere. This study is filling the gap in the academic literature by answering the question: "To what extent the 2019 Spitzenkandidaten represented their party's manifestos via their tweets or develop individualized campaigns?". The results reveal that the 2019 "Spitzenkandidaten" do not focus on personalization as a main tool in their Twitter behavior. Furthermore, the study shows how factors like the age of the candidate, their party orientation and whether candidates tweet or retweet more, is influencing the outcome.
Atualmente, o Twitter é uma das ferramentas online de eleição entre os atores políticos para fazerem campanha e estabelecerem uma ligação com os seus eleitorados, e o mesmo acontece com os "Spitzenkandidaten". O processo de "Spitzenkandidat", inicialmente implementado em 2014, tem sido um tema amplamente investigado. No entanto, com a personalização das campanhas a representar um dos principais fatores impulsionadores, é surpreendente ver a escassez de literatura sobre o assunto e, em particular, literatura relacionada com os principais candidatos na esfera do Twitter. Este estudo vem colmatar a lacuna na literatura académica ao responder à pergunta: "Até que ponto os Spitzenkandidaten de 2019 representaram os programas do seu partido através dos seus tweets ou desenvolveram campanhas individualizadas?". Os resultados revelam que os "Spitzenkandidaten" de 2019 não se centram na personalização como ferramenta principal no seu comportamento no Twitter. Além disso, o estudo demonstra de que forma fatores como a idade do candidato, a sua orientação partidária e se os candidatos fazem mais tweets ou retweets, têm influência no resultado.

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Dissertations / Theses on the topic 'Lead Candidate'

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