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No description available.

No description available.

No description available.

Doctor of Philosophy / Department of Biology / Lynn E. Hancock / Enterococci are gram-positive bacteria typically found as commensals in the gastro-intestinal tracts of most mammals. Enterococci, most notably Enterococcus faecalis and Enterococcus faecium, have become problematic causative agents of several nosocomially acquired infections including urinary tract infections, bacteremia, surgical sight infections, and endocarditis. These bacteria must first overcome the innate immune response in order to establish infection. Many bacteria produce capsular polysaccharides that contribute to pathogenesis by helping the microbe evade the host innate immune response. The capsular polysaccharide produced by E. faecalis has been shown to play a role in pathogenesis; however the mechanisms of innate immune avoidance were unknown. Moreover, the number of capsule serotypes produced by E. faecalis and the genetic differences that contribute to capsule serospecificity were in doubt. In the current study it is made clear that only two capsule serotypes are produced by E. faecalis and that both capsule serotypes contribute to evasion of the host innate immune system. This work shows two mechanisms by which the capsule of E. faecalis contributes to immune evasion. First, the presence of capsule inhibited complement mediated phagocytosis through limiting the detection of opsonic complement protein C3 on the surface of the bacteria. Secondly, the presence of capsule altered cytokine signaling of macrophages by shielding bacterial components from detection. Many pathogenic strains of E. faecalis also produce an extracellular protease known as gelatinase (GelE). This work also shows a novel mechanism involving GelE in innate immune evasion through the degradation of the anaphylatoxin C5a. Degradation of C5a by GelE resulted in decreased neutrophil recruitment in vitro. A rabbit model of endocarditis was employed to assess the effect of GelE production on disease development and progression. Rabbits infected with GelE producing strains had increased bacterial burdens in the heart compared to rabbits infected with strains that were GelE negative. Reduced phagocyte infiltration at primary and secondary infection sites was also observed in rabbits infected with GelE producing strains compared to GelE negative strains. The work presented here demonstrates that both the capsular polysaccharide and GelE play roles in E. faecalis evasion of innate immune responses. Moreover, these pathogenic determinants would be suitable targets for developing alternative therapeutics used to treat E. faecalis infections.

Le traitement des tumeurs cérébrales représente un défi d'envergure, puisqu'elles sont isolées du reste du corps par la barrière hémato-encéphalique. Il est donc impératif d'accroître nos connaissances sur les cellules composant ces tumeurs. L'une des hypothèses émergentes concerne la présence d'une sous-population spécifique de cellules au sein de la tumeur, les cellules souches cancéreuses (CSC), impliquées dans l'initiation et la récurrence des cancers. Les marqueurs de surfaces des CSC varient largement selon le tissu d'intérêt, mais il semble que CD133, une glycoprotéine membranaire, soit une signature commune à plusieurs CSC. S'il est courant de traiter le cancer en ciblant les cellules cancéreuses elles-mêmes, cibler le microenvironnement dans lequel évolue la tumeur est une avenue thérapeutique prometteuse. En effet, les cellules endothéliales (CE) au sein d'une tumeur sont connues pour avoir des propriétés différentes des CE normales. Ces cellules endothéliales tumorales (CET) peuvent donc constituer une cible supplémentaire pour inhiber sélectivement la croissance tumorale. À l'aide d'une lignée de médulloblastome (DAOY), nous avons identifié et évalué de nouvelles caractéristiques cellulaires et moléculaires impliquées dans la régulation du phénotype invasif associé à la formation de structures comparables aux neurosphères formées par les CSC CD133(+). De plus, nous avons apporté de nouvelles informations concernant les propriétés chimiopréventives du sulforaphane (SFN), un composé naturel retrouvé principalement dans le brocoli, en ciblant spécifiquement les CET cérébrales possiblement impliquées dans la cooption vasculaire. En utilisant la technologie de l'ARN interférant, nous avons montré que MMP-9 et MT1-MMP, deux métalloprotéinases matricielles importantes pour l'invasion cellulaire, les métastases et la résistance à la radiation, avaient un rôle crucial dans la formation par les DAOY de structures apparentées aux neurosphères CD133(+). De plus, nous avons mis en évidence une inhibition presque complète (> 90 %) de la migration des HBMEC (human brain microvascular endothelial cell) activées par un carcinogène, le phorbol 12-myristate 13-acétate (PMA). Ainsi, nos résultats suggèrent que les molécules présentes dans notre diète pourraient cibler les CET cérébrales composant la masse tumorale. En somme, nous proposons que MMP-9 constitue une cible de choix pour le traitement du cancer, que ce soit au niveau du compartiment tumoral ou vasculaire. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Cellule souche cancéreuse (CSC), Cellule endothéliale tumorale (CET), Sulforaphane (SFN), Métalloprotéinase matricielle-9 (MMP-9), Tumeur cérébrale.

Diabetic nephropathy is a common diabetic microvascular disease with a prevalence of about 10% to 42%. Research has shown that neutrophil gelatinase-associated lipocalin (NGAL) levels would increase rapidly in the urine and blood of patients with acute kidney failure. NGAL may represent an early and predictive kidney injury biomarker due to the increase of NGAL occurs earlier than that of molecules (creatinine, cystatin C and £]2-microglobulin) for traditional assessment of renal injury in renal disease samples. To evaluate the association of plasma level of NGAL and £]2-microglobulin with diabetic nephropathy, this study was performed on 21 diabetic patients without nephropathy as the control group and 21 patients with diabetic nephropathy stage 2, 26 patients with stage 3, 9 patients with stage 4 and 16 patients stage 5 as the study group. Collection of blood and measurements of all cases were approved by the ethical committee. The results indicate that the levels of blood urea nitrogen (BUN), creatinine, NGAL, and £]2-microglobulin of study group were significantly higher than control group (P<0.001), while the glomerular filtration rate (GFR) was significantly lower than the control group (P<0.001). Linear regression analysis show that NGAL was positively correlated with white blood cells, BUN, creatinine, £]2-micrglobulin and negatively correlated with GFR; and £]2-micrglobulin was positively correlated with BUN, creatinine, NGAL and negatively correlated with GFR. All results indicate that plasma NGAL levels in diabetic nephropathy were positively correlated with renal function parameters, and closely correlated with kidney injury, suggesting that NGAL may play an important role in the progression of diabetic nephropathy.

Enterococos são bactérias que exercem um papel muito importante na produção de vários alimentos fermentados e também podem ser usadas como probióticos. A presença e o crescimento de enterococcos em alimentos fermentados como queijos e lingüiças conferem a esses produtos características organolépticas únicas. Em contrapartida, sua presença nos alimentos também está associada com falta de higiene durante a manipulação. Estes microrganismos também estão relacionados com o desenvolvimento de algumas doenças, como endocardites, septicemia, infecções do trato geniturinário, entre outras. A presença de características de virulência aumenta o potencial de infecção do microrganismo e a severidade da doença a ele relacionada. Com o objetivo de avaliar possíveis modificações fenotípicas e genotípicas de amostras de enterococos isoladas de frango, durante a subcultura destas cepas no laboratório, várias análises foram realizadas como: a presença dos fatores de virulência; proteína de superfície (esp) e gelatinase (gelE), do operon fsr-regulador do gelE, a expressão fenotípica do gelE, a capacidade de formação de biofilme e a resistência a antimicrobianos, desinfetantes e antisépticos. Quarenta isolados de Enterococcus sp. foram avaliados quanto a presença dos genes gelE, esp, operon-fsr, sprE por PCR, a atividade gelatinolítica por testes bioquímicos convencionais, resistência a antimicrobianos, antisépticos e desinfetantes por antibiograma e formação de biofilme pelo método cristal violeta. Todos os testes foram realizados na 1º geração e na 12º geração das cepas. 85% dos isolados produziram gelatinase e em 92,5% dos isolados o gene gelE estava presente na 1º geração. A análise do fsr-operon destes isolados do primeiro cultivo demonstrou que o gene fsrA estava presente em 35 isolados e o fsrC em 37 isolados e a presença destes genes pareceu não ter correlação com a atividade gelationolítica. O gene fsrB estava presente em todos os isolados (35) que apresentaram atividade gelatinolítica sugerindo que a presença deste gene é importante na expressão desta enzima. Após o subcultivo, apenas um isolado perdeu a atividade gelatinolítica e 15 perderam o gene gelE. Doze isolados perderam pelo menos um gene do fsr-operon durante a subcultura, porém nenhum destes perdeu a capacidade de expressar a enzima gelatinase talvez devido à presença do gene fsrB. O gene sprE foi detectado em 34 isolados na primeira geração e na 12º geração em apenas 20 isolados. O gene da proteína de superfície de Enterococcos (Esp), não foi encontrado em nenhum dos isolados. O antibiograma do isolados no primeiro cultivo demonstrou que 100% dos isolados foram sensíveis a ampicilina e a gentamicina, 95% sensíveis a vancomicina, 85% a ciprofloxacina, 5% a tetraciclina, 65% a eritromicina e 52,5% a cloranfenicol tanto na 1º quanto na 12º geração. Após a subcultura a susceptibilidade dos isolados aumentou a eritromicina (67,5%) e ao cloranfenicol (80%). Quanto ao perfil de resistência aos detergentes e anti-sépticos de uso comercial, todos os isolados apresentaram fenótipo de resistentes ao linear alquilbenzeno sulfonato (LAS) e ao triclosan durante a subcultura. Todos isolados foram suscetíveis ao formaldeído, mas se tornaram resistentes ao 8,5% hipoclorito de sódio e a clorexidina durante a subcultura. Em geral, todos os isolados foram formadores de biofilme e a produção de gelatinase parece ser necessária para esta formação. O perfil genético não pareceu ter relação com a formação de biofilme. Tanto o perfil genotípico quanto o fenotípico pode sofrer alterações durante a subcultura das cepas no laboratório. / Enterococci are bacteria that have a very important role in the production of various fermented foods and can also be used as probiotics. The presence and growth of enterococci in fermented foods like cheese and sausages bring to these products unique organoleptic characteristics. However, their presence in foods is also associated with lack of hygiene during handling. These microorganisms are also related to the development of some diseases such as endocarditis, septicemia, genitourinary infections, among others. The presence of virulence characteristics increases the potential infection of the organism and severity of disease related to it. The aim of the present study is analyze the possible changes of phenotypic and genotypic of enterococci isolated from chicken, during the subculture of the strains in the laboratory, the presence of virulence factors: enterococcal surface protein (esp) and gelatinase (gelE), operon-fsr gelE regulator, gelE phenotypic expression, the ability of biofilm formation and antibiotic, disinfectant and antiseptic resistance were determined in samples of enterococci isolated from chicken. The presence of gelE, esp operon-fsr and sprE genes were evaluated by PCR, gelatinase activity were observed by conventional biochemical tests, antibiotics resistance, antiseptics and disinfectants resistance were analyzed by standard disk diffusion method and biofilm formation were detected following the crystal violet staining method in forty enterococci isolates from chicken. All tests were performed in the 1st generation and 12th generation. 85% of the isolates produced gelatinase and in 92.5% of the isolated the gelE gene was present in the 1st generation. The analysis of operon-fsr in the 1st generation of these isolates showed that the fsrA gene was present in 35 isolates and fsrC gene was present in 37 isolates and the presence of these genes seemed to have no correlation with the gelatinase activity. The fsrB gene was present in all isolates (35) with gelatinase activity suggesting that the presence of this gene is important in the expression of this enzyme. After subculture, only one isolate lost the gelatinase activity and 15 isolates lost the gelE gene. Twelve isolates lost at least one gene of the operon-fsr during laboratory subculture, but none of these isolates lost the ability to express the enzyme gelatinase probably due the presence of the fsrB gene. The sprE gene was detected in 34 isolates in the 1st generation and in 12th generation only 20 isolates maintained this gene. The protein surface of enterococci gene (Esp), was not found in any isolate. The antibiogram of the isolates showed that 100% of the isolates were susceptible to ampicillin and gentamicin, 95% susceptible to vancomycin, 85% to ciprofloxacin, tetracycline 5%, 65% to erythromycin and 52.5% to chloramphenicol in the 1st generation. After subculture the susceptibility of isolates to erythromycin (67.5%) and chloramphenicol (80%) increased. As the profile of resistance to detergents and antiseptics for commercial use, all isolates showed resistance phenotype of the linear alkylbenzene sulfonate (LAS) and triclosan during subculture. All isolates were susceptible to formaldehyde, but became resistant to 8.5% sodium hypochlorite and chlorhexidine during the subculture. In general, all isolates were biofilm formers. Gelatinase production appears to be required for biofilme formation. The genetic profile did not appear to have relation with the formation of biofilms. Genotypic and the phenotypic profile may change during the subculture of the strains in the laboratory.

Enterococos são bactérias que exercem um papel muito importante na produção de vários alimentos fermentados e também podem ser usadas como probióticos. A presença e o crescimento de enterococcos em alimentos fermentados como queijos e lingüiças conferem a esses produtos características organolépticas únicas. Em contrapartida, sua presença nos alimentos também está associada com falta de higiene durante a manipulação. Estes microrganismos também estão relacionados com o desenvolvimento de algumas doenças, como endocardites, septicemia, infecções do trato geniturinário, entre outras. A presença de características de virulência aumenta o potencial de infecção do microrganismo e a severidade da doença a ele relacionada. Com o objetivo de avaliar possíveis modificações fenotípicas e genotípicas de amostras de enterococos isoladas de frango, durante a subcultura destas cepas no laboratório, várias análises foram realizadas como: a presença dos fatores de virulência; proteína de superfície (esp) e gelatinase (gelE), do operon fsr-regulador do gelE, a expressão fenotípica do gelE, a capacidade de formação de biofilme e a resistência a antimicrobianos, desinfetantes e antisépticos. Quarenta isolados de Enterococcus sp. foram avaliados quanto a presença dos genes gelE, esp, operon-fsr, sprE por PCR, a atividade gelatinolítica por testes bioquímicos convencionais, resistência a antimicrobianos, antisépticos e desinfetantes por antibiograma e formação de biofilme pelo método cristal violeta. Todos os testes foram realizados na 1º geração e na 12º geração das cepas. 85% dos isolados produziram gelatinase e em 92,5% dos isolados o gene gelE estava presente na 1º geração. A análise do fsr-operon destes isolados do primeiro cultivo demonstrou que o gene fsrA estava presente em 35 isolados e o fsrC em 37 isolados e a presença destes genes pareceu não ter correlação com a atividade gelationolítica. O gene fsrB estava presente em todos os isolados (35) que apresentaram atividade gelatinolítica sugerindo que a presença deste gene é importante na expressão desta enzima. Após o subcultivo, apenas um isolado perdeu a atividade gelatinolítica e 15 perderam o gene gelE. Doze isolados perderam pelo menos um gene do fsr-operon durante a subcultura, porém nenhum destes perdeu a capacidade de expressar a enzima gelatinase talvez devido à presença do gene fsrB. O gene sprE foi detectado em 34 isolados na primeira geração e na 12º geração em apenas 20 isolados. O gene da proteína de superfície de Enterococcos (Esp), não foi encontrado em nenhum dos isolados. O antibiograma do isolados no primeiro cultivo demonstrou que 100% dos isolados foram sensíveis a ampicilina e a gentamicina, 95% sensíveis a vancomicina, 85% a ciprofloxacina, 5% a tetraciclina, 65% a eritromicina e 52,5% a cloranfenicol tanto na 1º quanto na 12º geração. Após a subcultura a susceptibilidade dos isolados aumentou a eritromicina (67,5%) e ao cloranfenicol (80%). Quanto ao perfil de resistência aos detergentes e anti-sépticos de uso comercial, todos os isolados apresentaram fenótipo de resistentes ao linear alquilbenzeno sulfonato (LAS) e ao triclosan durante a subcultura. Todos isolados foram suscetíveis ao formaldeído, mas se tornaram resistentes ao 8,5% hipoclorito de sódio e a clorexidina durante a subcultura. Em geral, todos os isolados foram formadores de biofilme e a produção de gelatinase parece ser necessária para esta formação. O perfil genético não pareceu ter relação com a formação de biofilme. Tanto o perfil genotípico quanto o fenotípico pode sofrer alterações durante a subcultura das cepas no laboratório. / Enterococci are bacteria that have a very important role in the production of various fermented foods and can also be used as probiotics. The presence and growth of enterococci in fermented foods like cheese and sausages bring to these products unique organoleptic characteristics. However, their presence in foods is also associated with lack of hygiene during handling. These microorganisms are also related to the development of some diseases such as endocarditis, septicemia, genitourinary infections, among others. The presence of virulence characteristics increases the potential infection of the organism and severity of disease related to it. The aim of the present study is analyze the possible changes of phenotypic and genotypic of enterococci isolated from chicken, during the subculture of the strains in the laboratory, the presence of virulence factors: enterococcal surface protein (esp) and gelatinase (gelE), operon-fsr gelE regulator, gelE phenotypic expression, the ability of biofilm formation and antibiotic, disinfectant and antiseptic resistance were determined in samples of enterococci isolated from chicken. The presence of gelE, esp operon-fsr and sprE genes were evaluated by PCR, gelatinase activity were observed by conventional biochemical tests, antibiotics resistance, antiseptics and disinfectants resistance were analyzed by standard disk diffusion method and biofilm formation were detected following the crystal violet staining method in forty enterococci isolates from chicken. All tests were performed in the 1st generation and 12th generation. 85% of the isolates produced gelatinase and in 92.5% of the isolated the gelE gene was present in the 1st generation. The analysis of operon-fsr in the 1st generation of these isolates showed that the fsrA gene was present in 35 isolates and fsrC gene was present in 37 isolates and the presence of these genes seemed to have no correlation with the gelatinase activity. The fsrB gene was present in all isolates (35) with gelatinase activity suggesting that the presence of this gene is important in the expression of this enzyme. After subculture, only one isolate lost the gelatinase activity and 15 isolates lost the gelE gene. Twelve isolates lost at least one gene of the operon-fsr during laboratory subculture, but none of these isolates lost the ability to express the enzyme gelatinase probably due the presence of the fsrB gene. The sprE gene was detected in 34 isolates in the 1st generation and in 12th generation only 20 isolates maintained this gene. The protein surface of enterococci gene (Esp), was not found in any isolate. The antibiogram of the isolates showed that 100% of the isolates were susceptible to ampicillin and gentamicin, 95% susceptible to vancomycin, 85% to ciprofloxacin, tetracycline 5%, 65% to erythromycin and 52.5% to chloramphenicol in the 1st generation. After subculture the susceptibility of isolates to erythromycin (67.5%) and chloramphenicol (80%) increased. As the profile of resistance to detergents and antiseptics for commercial use, all isolates showed resistance phenotype of the linear alkylbenzene sulfonate (LAS) and triclosan during subculture. All isolates were susceptible to formaldehyde, but became resistant to 8.5% sodium hypochlorite and chlorhexidine during the subculture. In general, all isolates were biofilm formers. Gelatinase production appears to be required for biofilme formation. The genetic profile did not appear to have relation with the formation of biofilms. Genotypic and the phenotypic profile may change during the subculture of the strains in the laboratory.