The need for a non-invasive, accurate, easy-to-use, and cost-effective colorectal cancer (CRC) detection device is apparent in the low survival rates seen in late-stage diagnoses. Once CRC has progressed past stage I, the 5-year survival rate drops significantly, and treatment options become less favourable. The best way to treat CRC is to catch it early. The development of an RNA-cleaving fluorogenic DNAzyme (RFD) holds the potential to remediate this deficiency. A DNAzyme, called RFD-FN1, was identified from a synthetic random-sequence DNA library to selectively bind to an unknown target associated with Fusobacterium nucleatum, which has been found to be overabundant in pre- and cancerous colorectal tissue and stool. Target recognition by the DNAzyme induces the cleavage of a fluorogenic substrate and generates a fluorescent signal to indicate the presence of the bacterium. This thesis outlines the efforts made towards functionalizing the F. nucleatum-responsive probe in stool samples to create a non-invasive screening test. RFD-FN1 is selective towards a heat-stable F. nucleatum protein, but its limit of detection is only 10^7 CFU/mL. Although able to detect spiked concentrations of F. nucleatum cells in processed stool samples, the use of heat, filtering, centrifugation, antibiotics, culturing or serial dilutions are not sufficient to detect the F. nucleatum that is naturally present in the diseased samples. Experiments designed to enrich the target concentration revealed that the target is not produced consistently in any growing condition tested. Size exclusion chromatography and mass spectrometry analysis identified five potential targets that RFD-FN1 may be responding to. Three candidate targets were cloned and purified, but they failed to induce RFD-FN1’s activity. Due to the COVID-19 pandemic, the purification of the final two proteins was not completed. Purifying the two candidate targets and testing their ability to induce RFD-FN1 represents future research efforts. If the target for the DNAzyme is confirmed, a reselection for a more sensitive DNAzyme, that can function in human stool, can be attempted. / Thesis / Master of Health Sciences (MSc)

Aptamers are nucleic acid ligands that bind to a specific target molecule. They are discovered by in-vitro selection, whereby binding sequences are selected from a large library of random sequences through iterative affinity steps. Aptamers are used as molecular recognition elements in aptamer-based, as such, creating aptamers with high affinity and specificity to their targets is important to the field. Ligands with two binding sites have been reported to have enhanced binding affinity than ligands with one binding site. To improve the quality of aptamers for downstream applications, multidomain selection is proposed as a new method for selecting aptamers compatible with dimerization. Here, we applied the multidomain selection approach to Fusobacterium nucleatum DnaK and produced aptamers that target the N-terminal domain (NTD) and the C-terminal domain (CTD) of DnaK. The top aptamer for DnaK-NTD had a Kd of 59.7 nM, and for DnaK-CTD had a Kd of 202.0 nM. However, the aptamers did not bind to the full-length DnaK and could not be dimerized. Multiple-site binding offers greater flexibility in the design of detection systems, which could provide higher selectivity and sensitivity than aptamers found through standard approaches. Validation of a method to discover aptamers compatible with dimerization would result in the development of a targeted approach to discover high-quality aptamers for bacterial proteins that can be used in bacteria-detection techniques. / Thesis / Master of Science (MSc)

Aggregatibacter actinomycetemcomitans e Fusobacterium nucleatum são microrganismos gram-negativos presentes nos processos inflamatórios e nas diferentes formas da doença periodontal. Ambos formam parte da microbiota residente da cavidade bucal humana podendo levar ao desenvolvimento de infecções endógenas ou exógenas. Neste estudo, as avaliações qualitativa, quantitativa e genotípica de A. actinomycetemcomitans e F. nucleatum isolados de pacientes com gengivite, periodontite crônica e indivíduos sadios foram realizadas. Biofilmes subgengivais de 70 pacientes com gengivite, 75 com periodontite crônica e 95 indivíduos saudáveis foram avaliados. A. actinomycetemcomitans foi isolado em 2 (2,8%) pacientes com gengivite, 4 (5,3%) com periodontite e 5 (5,3%) sadios; e F. nucleatum em 13 (18,6%) pacientes com gengivite, 20 (26,6%) com periodontite crônica e 19 (20%) sadios. Ambos os microrganismos foram isolados em 5 (7,1%) pacientes com gengivite, 9 (12%) com periodontite crônica e 3 (3,15%) sadios. Por PCR, os DNA de A. actinomycetemcomitans foram detectados em 23 (32,8%) pacientes com gengivite, 20 (26,6%) com periodontite crônica e 38 (40%) indivíduos saudáveis; e de F. nucleatum em 17 (24,3%) pacientes com gengivite, 11 (14,6%) com periodontite e 19 (20%) sadios. Em associação esses microrganismos foram detectados em 23 (32,8%) pacientes com gengivite, 40 (53,3%) com periodontite crônica e 17 (17,8%) sadios. A. actinomycetemcomitans isolados de pacientes com gengivite pertenceram aos biotipos I, II, IV, V e X, e aos sorotipos a, c, e e. Em pacientes com periodontite foram encontrados os biotipos II, VI e X, e os sorotipos a, b, e c, sendo o sorotipo c o mais predominante (80%); e em indivíduos sadios os biotipos II e X, e os sorotipos b e c. Os valores quantitativos de A. actinomycetemcomitans para os três grupos analisados variaram em número de cópias de 0 a 1,14 x 108, e de F. nucleatum de 0 a 3,98 x 106. Os resultados obtidos por AP-PCR mostram a heterogeneidade dos isolados de A. actinomycetemcomitans e de F. nucleatum nos diferentes grupos clínicos de pacientes avaliados. Esses resultados comparativos poderão ser levados em consideração pelos clínicos para melhor direcionar o tratamento da doença periodontal, colaborando de forma efetiva para o seu monitoramento. / Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are gram-negative microorganisms observed in inflammatory processes and different forms of periodontal disease. Both are part of the human oral resident microbiota which may cause endogenous or exogenous infections. In this study, a qualitative, quantitative and genotypic analysis of A. actinomycetemcomitans and F. nucleatum isolated from patients with gingivitis, chronic periodontitis and healthy subjects were determined. Subgingival biofilms of 70 patients with gingivitis, 75 with chronic periodontitis and 95 healthy subjects were evaluated. A. actinomycetemcomitans was isolated in 2 (2,8%) patients with gingivitis, 4 (5,3%) with periodontitis and 5 (5,3%) healthy individuals; and F. nucleatum in 13 (18,6%) patients with gingivitis, 20 (26,6%) with chronic periodontitis and 19 (20%) healthy. Both microorganisms were identified in 5 (7,1%) patients with gingivitis, 9 (12%) with chronic periodontitis and 3 (3,15%) healthy. By PCR, DNA of A. actinomycetemcomitans were detected in 23 (32,8%) patients with gingivitis, 20 (26,6%) with chronic periodontitis and 38 (40%) healthy individuals; and F. nucleatum 17 (24,3%) patients with gingivitis, 11 (14,6%) with periodontitis and 19 (20%) healthy. In association, microorganisms were detected in 23 (32,8%) patients with gingivitis, 40 (53,3%) with chronic periodontitis and 17 (17,8%) healthy. A. actinomycetemcomitans isolated from patients with gingivitis belonged to biotype I, II, IV, V, X, and serotypes a, c and e. In patients with periodontitis biotypes II, VI and X and serotypes a, b, and c were found and serotype c was the most predominant (80%); and healthy individuals biotypes II and X, and serotypes b and c. Quantitative values for A. actinomycetemcomitans in the three patients groups were ranged from 0 to 1.14 x 108 and F. nucleatum 0 to 3.98 x 106. The results of this study by AP-PCR showed the heterogeneity of A. actinomycetemcomitans and F. nucleatum in the different clinical status. These comparative results can be considered by dentists for the treatment of periodontal disease and its effective monitoring.

Aggregatibacter actinomycetemcomitans e Fusobacterium nucleatum são microrganismos gram-negativos presentes nos processos inflamatórios e nas diferentes formas da doença periodontal. Ambos formam parte da microbiota residente da cavidade bucal humana podendo levar ao desenvolvimento de infecções endógenas ou exógenas. Neste estudo, as avaliações qualitativa, quantitativa e genotípica de A. actinomycetemcomitans e F. nucleatum isolados de pacientes com gengivite, periodontite crônica e indivíduos sadios foram realizadas. Biofilmes subgengivais de 70 pacientes com gengivite, 75 com periodontite crônica e 95 indivíduos saudáveis foram avaliados. A. actinomycetemcomitans foi isolado em 2 (2,8%) pacientes com gengivite, 4 (5,3%) com periodontite e 5 (5,3%) sadios; e F. nucleatum em 13 (18,6%) pacientes com gengivite, 20 (26,6%) com periodontite crônica e 19 (20%) sadios. Ambos os microrganismos foram isolados em 5 (7,1%) pacientes com gengivite, 9 (12%) com periodontite crônica e 3 (3,15%) sadios. Por PCR, os DNA de A. actinomycetemcomitans foram detectados em 23 (32,8%) pacientes com gengivite, 20 (26,6%) com periodontite crônica e 38 (40%) indivíduos saudáveis; e de F. nucleatum em 17 (24,3%) pacientes com gengivite, 11 (14,6%) com periodontite e 19 (20%) sadios. Em associação esses microrganismos foram detectados em 23 (32,8%) pacientes com gengivite, 40 (53,3%) com periodontite crônica e 17 (17,8%) sadios. A. actinomycetemcomitans isolados de pacientes com gengivite pertenceram aos biotipos I, II, IV, V e X, e aos sorotipos a, c, e e. Em pacientes com periodontite foram encontrados os biotipos II, VI e X, e os sorotipos a, b, e c, sendo o sorotipo c o mais predominante (80%); e em indivíduos sadios os biotipos II e X, e os sorotipos b e c. Os valores quantitativos de A. actinomycetemcomitans para os três grupos analisados variaram em número de cópias de 0 a 1,14 x 108, e de F. nucleatum de 0 a 3,98 x 106. Os resultados obtidos por AP-PCR mostram a heterogeneidade dos isolados de A. actinomycetemcomitans e de F. nucleatum nos diferentes grupos clínicos de pacientes avaliados. Esses resultados comparativos poderão ser levados em consideração pelos clínicos para melhor direcionar o tratamento da doença periodontal, colaborando de forma efetiva para o seu monitoramento. / Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are gram-negative microorganisms observed in inflammatory processes and different forms of periodontal disease. Both are part of the human oral resident microbiota which may cause endogenous or exogenous infections. In this study, a qualitative, quantitative and genotypic analysis of A. actinomycetemcomitans and F. nucleatum isolated from patients with gingivitis, chronic periodontitis and healthy subjects were determined. Subgingival biofilms of 70 patients with gingivitis, 75 with chronic periodontitis and 95 healthy subjects were evaluated. A. actinomycetemcomitans was isolated in 2 (2,8%) patients with gingivitis, 4 (5,3%) with periodontitis and 5 (5,3%) healthy individuals; and F. nucleatum in 13 (18,6%) patients with gingivitis, 20 (26,6%) with chronic periodontitis and 19 (20%) healthy. Both microorganisms were identified in 5 (7,1%) patients with gingivitis, 9 (12%) with chronic periodontitis and 3 (3,15%) healthy. By PCR, DNA of A. actinomycetemcomitans were detected in 23 (32,8%) patients with gingivitis, 20 (26,6%) with chronic periodontitis and 38 (40%) healthy individuals; and F. nucleatum 17 (24,3%) patients with gingivitis, 11 (14,6%) with periodontitis and 19 (20%) healthy. In association, microorganisms were detected in 23 (32,8%) patients with gingivitis, 40 (53,3%) with chronic periodontitis and 17 (17,8%) healthy. A. actinomycetemcomitans isolated from patients with gingivitis belonged to biotype I, II, IV, V, X, and serotypes a, c and e. In patients with periodontitis biotypes II, VI and X and serotypes a, b, and c were found and serotype c was the most predominant (80%); and healthy individuals biotypes II and X, and serotypes b and c. Quantitative values for A. actinomycetemcomitans in the three patients groups were ranged from 0 to 1.14 x 108 and F. nucleatum 0 to 3.98 x 106. The results of this study by AP-PCR showed the heterogeneity of A. actinomycetemcomitans and F. nucleatum in the different clinical status. These comparative results can be considered by dentists for the treatment of periodontal disease and its effective monitoring.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-09-13T12:33:03Z No. of bitstreams: 1 jobalvesdesouzafilho.pdf: 5002481 bytes, checksum: 64848c1386c2e939797e2ac86f5eddd4 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-09-13T12:46:33Z (GMT) No. of bitstreams: 1 jobalvesdesouzafilho.pdf: 5002481 bytes, checksum: 64848c1386c2e939797e2ac86f5eddd4 (MD5) / Made available in DSpace on 2016-09-13T12:46:33Z (GMT). No. of bitstreams: 1 jobalvesdesouzafilho.pdf: 5002481 bytes, checksum: 64848c1386c2e939797e2ac86f5eddd4 (MD5) Previous issue date: 2011-11-04 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Concentrações subinibitórias de antimicrobianos (CSI), frequentemente decorrentes de antibioticoterapia, podem resultar em alterações na biologia bacteriana, com implicações no seu potencial agressor. Esse efeito tem considerável importância para as bactérias da microbiota residente, em especial para Fusobacterium nucleatum, um dos mais proeminentes anaeróbios residentes em humanos. Os objetivos deste trabalho foram analisar os efeitos de concentrações subinibitórias (CSI) de antimicrobianos em características morfológicas, bioquímicas, fisiológicas e moleculares de F. nucleatum. A partir da linhagem F. nucleatum ATCC 25586 (denominada FnPAR), foram obtidas 14 linhagens selecionadas por 10 cultivos sucessivos em CSI de ampicilina (FnAMP+), ampicilina/sulbactam (FnAMS+), clindamicina (FnCLI+), cloranfenicol (FnCLO+), levofloxacina (FnLEV+), metronidazol (FnMET+) e piperacilina/tazobactam (FnPTZ+) e, subsequente, 10 cultivos na ausência das mesmas drogas. Foram avaliados o perfil de susceptibilidade aos antimicrobianos, a morfologia bacteriana, o perfil bioquímico, a formação de biofilme e o custo de fitness. Também foram realizados genotipagem e análise dos perfis protéicos. Para avaliação global das alterações fenotípicas e genotípicas foram obtidas matrizes de similaridade. O perfil de susceptibilidade mostrou sensibilidade diminuída para a maioria das linhagens derivadas, mesmo após o cultivo sem drogas. Alterações morfológicas e de complexidade celular foram observadas, principalmente nas linhagens cultivadas em CSI de β-lactâmicos (FnAMP+, FnAMS+ e FnPTZ+), que também expressaram capacidade diminuída para formação de biofilme. Contudo, a morfologia regular e a habilidade de formação de biofilme foram retomadas após o cultivo sem droga. As linhagens FnCLI, FnCLO, FnLEV e FnMET não apresentaram alterações morfológicas evidentes, porém, foi observado aumento na formação de biofilme, com destaque para FnCLI+. As linhagens FnMET+ e FnCLI+ apresentaram um alto custo de fitness. Foram observadas alterações no padrão de metabolismo de carboidratos e na atividade de enzimas microbianas. Comparado com a FnPAR, várias proteínas (de 4.5 a 240 kDa) foram positivamente ou negativamente reguladas nas linhagens derivadas. Observou-se polimorfismo no DNA em todas as linhagens derivadas. As matrizes de similaridade não mostraram relações entre o padrão de polimorfismo de DNA e as outras características. Entretanto, existe uma tendência de que as alterações bioquímicas estejam relacionadas com alterações nos perfis protéicos. CSI de antimicrobianos podem, de fato, induzir alterações em F. nucleatum, com reflexo direto na sua biologia. Estes resultados alertam para o risco de antibioticoterapia inadequada, que podem ter sérias implicações para a microbiologia clinica e doenças infecciosas e, ainda, interferir com a relação bactéria-hospedeiro. / Subinibitory Concentrations (SIC) of antimicrobials, often arising from antibioticotherapy, may result in alterations in bacterial biology with implications for its potential aggressor. This effect has considerable importance for the bacteria of resident microbiota, especially for Fusobacterium nucleatum, one of the most prominent anaerobes in humans. Our aim was to analyze the effects of antimicrobials SIC in morphological, biochemical, physiological and molecular characteristics of F. nucleatum. From the strain F. nucleatum ATCC 25586 (FnWLD) were obtained 14 strains selected by 10 successive culture on SIC of ampicillin (FnAMP+), ampicillin/sulbactam (FnAMS+), clindamycin (FnCLI+), chloramphenicol (FnCLO+), levofloxacin (FnLEV+), metronidazole (FnMET+) and piperacillin/tazobactam (FnPTZ+) and subsequent 10 cultures in the absence of the same drugs. We evaluated the antimicrobial susceptibility patterns, bacterial morphology, biochemical profile, biofilm formation and the fitness cost. We also performed genotyping and analysis of protein profiles. For the global evaluation of phenotypic and genotypic alterations, similarity matrices were obtained. The antimicrobial susceptibility patterns showed decreased sensitivity to most of derived strains, even after culture without drugs. Morphological and cell complexity alterations were observed, mainly in strains grown in SIC of β-lactam (FnAMP+, FnAMS+ and FnPTZ+), which also expressed decreased ability to biofilm formation. However, the regular morphology and the ability to biofilm formation were restored after culture without drug. The strains FnCLI, FnCLO, FnLEV and FnMET showed no apparent morphological changes, however, there was an increase in biofilm formation, especially for FnCLI+. The strains FnMET+ and FnCLI+ had a high fitness cost. Changes were observed in the carbohydrate metabolism patterns and activity of microbial enzymes. Compared with the FnWLD, several proteins (from 4.5 to 240 kDa) were positively or negatively regulated in the derived strains. It was observed polymorphism in the DNA in all derived strains. The similarity matrices showed no relationship between the DNA polymorphism patterns and other features. However, there is a tendency that the biochemical changes to be related to alterations in protein profiles. SIC of antimicrobials may, indeed, to induce alterations in F. nucleatum with direct impact on its biology. These results emphasize the risk of inadequate antibioticotherapy, which may have serious implications for the clinical microbiology and infectious diseases and also to interfere with the bacteria-host relationship.

Bakterier har alltid haft en stor inverkan på mänskligheten. För att diagnostisera bakteriella sjukdomar och behandla dem krävs identifiering av bakterien eller bakteriens relevanta egenskaper. Transportmedium har utvecklats för att hålla bakterierna vid liv från provtagning till analys. Syftet med studien var att utvärdera bakteriers viabilitet i det vätskebaserade mediet Copan Eswab jämfört med kolmedium (Copan swab). Bakterierna som ingick i studien var Campylobacter jejuni, Streptococcus pneumoniae, Haemophilus influenzae, Niesseria gonorrhoeae och Fusobacterium nucleatum. Förutom jämförande mellan medierna genomfördes en jämförelse mellan Eswab i kyl och i rumstemperatur. Resultaten för H. influenzae (n=9) och N. gonorrhoeae (n=9) visade att Eswab gav lika många eller fler överlevande bakterier. Gällande F. nucleatum (n=9) visade resultaten att fler överlevde i Copan swab (Copanpinnar) de första 28 timmarna, men även att bakterien inte klarar mer än 28 timmar i rumstemperatur. Gällande S. pneumoniae (n=9) och C. jejuni (n=9) gav båda opålitliga svar. Ytterligare mätpunkter och studier krävs för att erhålla mer pålitliga resultat gällande hur länge bakterierna överlever i Eswab. / Bacteria have always had a great influence on mankind. To diagnose any bacterial disease and treat it it’s necessary to identify the bacteria or any relevant attributes. Different types of specimen transport have been developed to keep the bacteria alive from sampling until the analysis is performed. The purpose of the study was to evaluate the viability of bacteria in the fluid-based media Copan EswabTM compared with charcoal medium (Copan swab). Bacteria included in the study were: Campylobacter jejuni, Streptococcus pneumoniae, Haemophilus influenzae, Niesseria gonorrhoeae and Fusobacterium nucleatum. The study also tried to compare how bacteria survived in Eswab which was refrigerated and in Eswab room temperature. Results for H. influenzae (n=9) and N. gonorrhoeae (n=9) showed that an equal amount or more of the bacteria survived in Eswab. More of F. nucleatum (n=9) survived in Copan swab (Copan swab sticks) for the first 28 hours, additionally they showed that the bacteria won’t survive more than 28 hours in room temperature. Regarding S. pneumoniae (n=9) and C. jejuni (n=9) both displayed unreliable results. Overall more measurements and additional studies are needed for more reliable results.

Indiana University-Purdue University Indianapolis (IUPUI) / The primary goal of root canal treatment is to eliminate microbes from the root canal system, which is the cause of pulpal and periapical infections. Research shows that after a single visit of chemomechanical debridement microbes continue to remain within the canal system. An interappointment medication step has been advocated to maximize potential elimination of microbes within the root canal system. Previous studies have shown propolis to be antibacterial against common endodontic microbes. Studies have shown trends in different microbes being present in primary verus secondary endodontic infections. The majority of literature has focused on the efficacy of propolis against Enterococcus faecalis, a microbe commonly implicated in secondary endodontic 95 infections. The aim of this study was to demonstrate the efficacy of propolis against Fusobacterium nucleatum, a microbe commonly found in primary endodontic infections. This study aims to demonstrate the efficacy of propolis against a bacterium of primary endodontic infections (F. nucleatum) as well as against microbial biofilm to further support its potential use as a novel intracanal medicament. Dilutions of propolis were added to cultures of F. nucleatum in microtiter plates in a range from 390 μg/ml to 50,000 μg/ml. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and the minimum biofilm inhibitory concentration (MBIC) were determined. The MIC was determined of the total solution (biofilm+planktonic), planktonic, and biofilm (MBIC) after a 48-hour incubation period. The MBIC was determined by fixing biofilm to the wells and using crystal violet staining with spectrophotometry. The MBC was examined by plating solution from each concentration test well and reading the plates after 48 hours of incubation. The results show that the MIC of the total (biofilm+planktonic) appears to occur at a concentration of 6250 μg/ml. The MBIC appears to occur at the concentration of 1562.5 μg/ml. The planktonic results exhibit no significant difference in test and control wells. There was no MBC at any of the test concentrations. The propolis appears to inhibit bacterial growth and biofilm formation but does not appear to be bactericidal at any of the tested concentrations. The results of this study indicate that propolis has an MIC and MBIC when tested in vitro against F. nucleatum, although it does not show an MBC. There appears to be potentially significant interaction of propolis with biofilm as displayed by the lower concentration needed to exibit inhibitory effects on biofilm formation. This information 96 may contribute to the ability to develop a proper concentration of propolis to use in vivo when treating endodontic infections.

El objetivo del presente estudio fue determinar el efecto antibacteriano de la combinación de droga 3Mix y MP y de sus combinaciones alternativas contra Enterococcus faecalis y Fusobacterium nucleatum. Se empleó el método de dilución en caldo para determinar la concentración inhibitoria mínima (CIM) y la concentración bactericida mínima (CBM) y método de difusión en agar modificado para determinar el efecto antibacteriano de los vehículos. Se emplearon dos cepas ATCC Enterococcus faecalis y Fusobacterium nucleatum, con la combinación de componentes de la droga 3Mix, 3Mix-Cefaclor(reemplazo de minociclina por cefaclor) y 3Mix-Amoxicilina(reemplazo de minociclina por cefaclor) en las siguientes concentraciones: 25µg/ml; 6,25µg/ml; 1,56µg/ml; 0,39µg/ml; 0,195µg/ml; 0,097µg/ml y macrogol(M), propilenglicol(P) y su asociación. La CIM para 3Mix, 3Mix-cefaclor fue 0,39µg/ml y 0,195µg/ml para 3Mix-Amoxicilina mientras que CBM fue >25µg/ml; 25µg/ml; 6,25µg/ml respectivamente sobre Enterococcus faecalis, para Fusobacterium nucleatum la CIM de 3Mix, 3Mix-Cefaclor fue 0,195µg/ml y ≤0,097µg/ml para 3Mix-Amoxicilina, los cuales coincidieron con CBM. Se obtuvo inhibición de crecimiento bacteriano por parte macrogol y propilenglicol+macrogol, sin embargo propilenglicol no formó halo de inhibición sobre Enterococcus faecalis ni Fusobacterium nucleatum. La Combinación de droga 3Mix, 3Mix-Cefaclor y 3Mix-Amoxicilina presentaron efectos antibacterianos contra Enterococcus faecalis y Fusobacterium nucleatum.

Orientador: Ana Elizabete Silva / Coorientador: David J. Hughes / Banca: Marcelo Lima Ribeiro / Banca: Rui Manuel Vieira Reis / Banca: Débora Aparecida Pires de Campos Zuccari / Banca: Marilia De Freitas Calmon Saiki / Resumo: O câncer colorretal (CCR) está associado à patógenos como Fusobacterium nucleatum (Fn), que podem proporcionar um microambiente favorável para a tumorigênese em decorrência de alterações inflamatórias. Visando compreender o efeito de Fn no microambiente de lesões intestinais, avaliou-se a quantificação relativa (RQ) dessa bactéria em amostras de tecido de adenoma colorretal (ACR) e CCR, bem como sua correlação com a expressão de RNAm de mediadores inflamatórios (TLR2, TLR4, NFKB1, TNF, IL1B, IL6 e IL8) e de microRNAs (miRNAs) (miR-21-3p, miR-22-3p, miR-28-5p, miR-34a-5p e miR-135b-5p) envolvidos na resposta inflamatória e carcinogênese. Também delineou-se uma rede de interação miRNA:RNAm para auxiliar na compreensão da participação dos miRNAs no processo carcinogênico. Foram extraídos o DNA e o RNA de 27 amostras de tecido fresco de ACR e 43 de CCR e suas respectivas normais adjacentes. Os níveis de DNA de Fn e de RNAm dos mediadores inflamatórios e miRNAs foram quantificados por PCR quantitativo em tempo real (qPCR). Níveis elevados de Fn foram detectados em ACR (RQ=5,64) e mais acentuadamente em CCR (RQ=8,67). Observou-se expressão elevada do RNAm de TLR4, IL1B, IL8 e miR-135b em ACR, e de TLR2, IL1B, IL6, IL8, miR-34a e miR-135b em CCR em comparação com seus respectivos tecidos normais. Além disso, miR-22 e miR-28 foram encontrados com expressão reduzida em CCR. A expressão de RNAm de IL1B, IL6, IL8 e miR-22 foi positivamente correlacionada com a quantificação de Fn em CCR... / Abstract: Colorectal cancer (CRC) is associated with pathogens such as Fusobacterium nucleatum (Fn), which can provide a favorable microenvironment for tumorigenesis due to inflammatory changes. In order to understand the effect of Fn on the microenvironment of intestinal lesions, the relative quantification (RQ) of this bacterium was evaluated in samples of colorectal adenoma tissue (CRA) and CCR, as well as its correlation with the mRNA expression of inflammatory mediators (TLR2, TLR4, NFKB1, TNF, IL1B, IL6 e IL8), and microRNAs (miR-21-3p, miR-22-3p, miR-28-5p, miR-34a-5p e miR-135b-5p) involved in the inflammatory response and carcinogenesis. A miRNA: mRNA interaction network was also delineated to aid in the understanding of miRNA participation in the carcinogenic process. DNA and RNA were extracted from 27 fresh tissue samples of CRA and 43 of CRC and their respective adjacent normal ones. Fn and mRNA levels of the inflammatory mediators and miRNAs were quantified by quantitative real-time PCR (qPCR). Elevated levels of Fn were detected in CRA (RQ=5.64 and more markedly in CRC (RQ=8.67). High mRNA expression of TLR4, IL1B, IL8 and miR-135b in CRA, and of TLR2, IL1B, IL6, IL8, miR-34a and miR-135b in CRC were observed in comparison with their respective normal tissues. In addition, miR-22 and miR-28 were found downregulated in CRC. The mRNA expression of IL1B, IL6, IL8 and miR-22 was positively correlated with the quantification of Fn in CRC. The mRNA expression of miR-135b and ... / Doutor

Fusobacterium nucleatum is a saccharolytic Gram-negative anaerobic organism belonging to the so-called ‘orange complex’ which is believed to play an important role in the microbial succession associated with the pathogenesis of periodontal disease. Its genome contains niche-specific genes shared with the other inhabitants of dental plaque, which may help to explain its ability to survive and grow in the changing environmental conditions experienced in the gingival sulcus during the progression from health to disease. The pH of the gingival sulcus increases during the development of periodontitis and is thought to occur by the metabolism of nutrients supplied by gingival crevicular fluid. Studies have shown that F. nucleatum is partly responsible for the rise in pH and have concluded that in comparison to other plaque inhabitants, F. nucleatum has the greatest ability to neutralise acidic environments. In common with a number of other oral bacteria, F. nucleatum has also been shown to produce intracellular polyglucose (IP) from simple sugars such as glucose, galactose and fructose. Its response and adaptation to stressful environmental conditions such as pH is unknown. The overall aim of this study was, therefore, to determine how F. nucleatum copes with environmental stresses induced by pH changes. F. nucleatum was grown by continuous culture in a chemically defined medium at a growth rate corresponding to those measured in vivo. The effect on protein expression, and IP synthesis was examined during steady-state growth at high (>7.2<7.8) or low pH (pH 6.4). The present study also investigated the response of F. nucleatum to growth at pH 8.2. It was found that the organism grew as a biofilm and this corresponded with an increase in cellular hydrophobicity and decreased IP levels. Optimal growth pH’s differed between the different sub-species used in this study. In response to pH stress, F. nucleatum changed its amino acid and glucose utilisation and increased IP synthesis at the expense of cell numbers. Pulsing the chemostat with glutamic acid or serine produced an increase in IP synthesis and the pattern of end-products observed was dependent upon the amino acid being fermented. The effect on IP synthesis in response to increased levels of exogenous fermentable amino acids was also compared during concomitant fructose or glucose fermentation. Growth media containing fermentable amino acids and supplemented with fructose produced higher cell numbers and non-detectable levels of IP compared to media containing glucose. The differential expression of cytoplasmic- and cell envelope-proteins induced by changes in pH were identified by two-dimensional gel electrophoresis. The results represent the first proteomic investigation of F. nucleatum. Twenty-two cytoplasmic proteins were found to have altered expression in response to external pH. At low (sub-optimal) pH, proteins associated with the generation of ATP and ammonia were up-regulated, the latter contributing to the alkalinisation of the gingival sulcus. Conversely, neutral to alkaline pH conditions led to the upregulation of enzymes involved in energy storage. The study also identified several proteins associated with iron limitation and fatty acid synthesis which might not otherwise have been identified as part of the pH-dependent response. In response to growth at pH 7.8, 14 cell envelope proteins were identified as having significantly altered expression. Down-regulated proteins included those associated with uptake of C4 di-carboxylates and phosphorus, a potential membrane protease and an enzyme associated with amino acid fermentation. The up-regulation of a transcriptional regulator linked to the repression of sugar metabolism was also reported along with proteins linked to the transport of iron. The periplasmic chaperone, peptidyl prolyl cis trans isomerase, which is responsible for the folding of outer membrane proteins, was also found to be up-regulated. In conclusion, the proteomic investigation of protein expression by F. nucleatum identified gene products which form part of the organism’s coordinated stress response to changes in environmental pH. In addition to these, the physiological based studies also presented help to explain the organism’s persistence during the transition from health to disease in vivo. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339503 / Thesis (Ph.D.) - University of Adelaide, Dental School, 2008