Dissertations / Theses on the topic 'Nucleatum'

Foram determinadas as atividades proteolíticas do bacilo anaeróbio Fusobacterium nucleatum, presente em várias infecções oral e sistêmica humana. As reações foram otimizadas quanto a pH, temperatura, tempo de reação, volume da fonte de enzima e concentração de substrato. Foram utilizados os substratos sintéticos b-naftilamida (Cys-Na, Ser-Na, Leu-Na, Glu-Na, Lys-Na e BANA), o carboxi-L-tirosina p-nitrofeniléster (CTN) e o substrato natural azoalbumina. Reação do sobrenadante ocorreu apenas com o substrato Glu-Na. Nas células vivas, as reações ocorreram com Cys-Na, Ser-Na e Glu-Na; e com as células lisadas, com os substratos Glu-Na, Leu-Na e CTN. O pH ótimo variou de 6,0 a 7,5 em todas as reações, com excessão para o CTN (pH 13). A temperatura ótima oscilou entre 30 e 40°C. O tempo ótimo de reação foi 60 minutos, exceto para as células vivas com o Glu-Na (40 min), células lisadas (20 min) e o substrato CTN (80 min). Não houve atividade com a azoalbumina. A atividade enzimática foi avaliada por vários inibidores de protease, sendo detectada a presença de metalo, serina, cisteína e aspartato proteases.
The proteolytic activities of the anaerobe bacillus Fusobacterium nucleatum present in several oral and systemic human infections were determined. The reactions were optimized in their pH, temperature, reaction time, enzyme source and substrate volume. The synthetic substrates b-?naphthylamides (Cys-Na, Ser-Na, Leu-Na, Glu-Na, Lys-Na and BANA), carboxi-L-tyrosine p-nitrophenylester (CTN), and natural substrate azoalbumin were used. With supernatants reaction occurred only with Glu-Na. In the living cells, reacted with Cys-Na, Ser-Na and Glu-Na; and lysate cells with Glu-Na, Leu-Na and CTN. Optimal pH ranged from 6.0 to 7.5 in all the reaction, except for CTN (pH 13). Optimal temperature oscillated between 30 and 40ºC. The optimal reaction time was 60 minutes, except for Glu-Na with living cells (40 min), lysate cells (20 min), and CTN substrate (80 min). There was no activity with azoalbumin. The enzyme activity by several protease inhibitors was assessed and the presence of metallo, serine, cysteine and aspartato protease was detected.

Fusobacterium nucleatum é uma espécie bacteriana Gram-negativa, anaeróbia estrita e uma das espécies frequentemente encontradas nas infecções primárias do sistema de canais radiculares. Esta espécie tem grande importância na formação de biofilmes por ser uma ponte de união entre espécies que não são capazes de interagir. Os micro-organismos constituintes de biofilmes trocam material genético, aumentando a tolerancia dos mesmos e é quase impossível um isolado clínico ter os genes totalmente iguais à cepa padrão de coleções de cultura como da ATCC (American Type Culture Colection). O presente estudo investigou a espécie bacteriana anaeróbia Fusobacterium nucleatum isolada de canais radiculares, comparando-a com sua cepa de referência. Foi feito a comparação da suscetibilidade microbiana in vitro por meio de cultura microbiológica pelo método do E-test, com as cepas em crescimento planctônico e em biofilme. Também foi definido um protocolo de Purificação de RNA para esta espécie em ambas as condições de crescimento. As cepas clínicas de F. nucelatum foram isoladas por meio da cultura microbiológica de 23 pacientes que apresentavam dentes com infecção primária e periodontite apical visível em radiografia. Foi feito isolamento e identificação da espécie por série bioquímica com testes comerciais (Sistema Api, Bio-Meriéux, França) e PCR convencional, sendo no total 4 isolados clínicos investigados. Foi verificada a suscetibilidade antimicrobiana dos seguintes antibióticos: Amoxicilina, Amoxicilina + ácido clavulânico, Ampicilina, Azitromicina, Clindamicina, Eritromicina e Metronidazol. O protocolo para purificação de RNA foi feito com microesferas de zircônia, dispositivo bead beater, kit comercial RNeasy (Qiagen) e transcrição para DNA complementar (cDNA). A qualidade da purificação foi testada quanto a sua capacidade de amplificação pela reação em cadeia da polimerase em tempo real (qPCR) utilizando primer para o gene 16s RNA específico para F. nucelatum. Todas as cepas testadas foram 100% suscetíveis a Amoxicilina + ácido clavulânico, Ampicilina, Azitromicina, Clindamicina e Metronidazol. Ambos os tipos de crescimento bacteriano demonstraram resistência somente à eritromicina. O protocolo proposto para a purificação do RNA de F. nucelatum dos isolados em crescimento planctônico e em biofilme foi eficaz. A média do rendimento do RNA das amostras para as bactérias em crescimento planctônico foi de 514,2 ng/μL (DP ± 397,7) e para as amostras em biofilme foi de 377,1 ng/μL (DP± 144,1). Os valores encontrados sugerem uma boa qualidade de RNA, livre de contaminação por proteínas. Todas as cepas de Fusobacterium nucleatum isoladas de canais radiculares, assim como a cepa ATCC foram suscetíveis aos antibióticos testados, com exceção do antibiótico eritromicina em ambos os tipos de crescimento bacteriano. As bactérias em biofilme apresentaram aumento na tolerância frente aos agentes antimicrobianos, com diferença estatística. O protocolo estabelecido para a purificação do RNA de cepas de Fusobacterium nucleatum cultivadas em fase planctônica e em biofilmes teve êxito com amplificação por qPCR.
Fusobacterium nucleatum is a Gram-negative bacterial species, strict anaerobic and one of the species often found in primary infection of the root canal system. This species has great importance in biofilm formation to be a union bridge between species which are not able to act alone. The constituent microorganisms of the biofilm exchange each tother genetic material, increasing the strength of them. It is almost impossible for a clinical isolate have genes totally equal to a standard strain, such as strains of culture collections like ATCC (American Type Culture Collection). The present study investigated anaerobic bacterial species Fusobacterium nucleatum isolated from root canals, comparing them to the ATCC strain. The microbial in vitro susceptibility of biofilm and planktonic growth of the strains was compared by means of microbiological culture and the E-test method, with the antibiotics Amoxicillin, Amoxicillin + clavulanic acid, Ampicillin, Azithromycin, Clindamycin, Eritromycin and Metronidazole.. Also, a RNA Purification protocol for the strains under the same growth conditions was defined. Clinical isolates were obtained by microbiological samples of patients with teeth with pulp necrosis and apical periodontitis visible on radiographs. The species isolation and identification were performed using commercial biochemical tests (Sistema Api, Bio-Meriéux, France) and conventional PCR, obtaining four clinical isolates. The protocol for RNA purification was done with zirconia beads, bead beater device and commercial kit RNeasy (Qiagen) and transcribed into complementary DNA (cDNA). The quality of purification was tested for its ability of amplification by real time polymerase chain reaction (qPCR) using primer for the gene 16s RNA specific for F. nucleatum. All tested trains were 100% susceptible to amoxicillin + clavulanic acid, ampicillin, azithromycin, clindamycin and metronidazole. Both types of bacterial growth showed resistance to Erythromycin. Bacteria in biofilm showed a decrease in susceptibility to all antibiotics, but without statistical difference. The protocol proposed for the purification of RNA of F. nucleatum was effective, in the planktonic and the biofilm growth. The average yield of RNA samples for bacteria in planktonic growth was 514.2 ng /μL (SD ± 397.7) and the samples in biofilm was 377.1 ng / μL (SD ± 144.1). These found values suggest a good quality of RNA, free of protein contamination. The established protocol for the purification of the RNA of the Fusobacterium nucleatum strains, grown in biofilm and planktonic phase, had successfully amplified by qPCR.

Fusobacterium nucleatum is a Gram-negative bacterium that serves as a bridging organism in polymicrobial biofilms within the oral cavity. Although the bacterium is abundant in healthy gingival tissue, recent studies have found that F. nucleatum is associated with a wide-spectrum of human diseases which include periodontal disease, preterm birth, endocarditis, colorectal cancer, and pancreatic cancer. Previous studies of F. nucleatum virulence have uncovered two surface adhesins, Fap2 and FadA, that interact with the surface of human cells; however, the study of new virulence factors was previously limited as there was no gene deletion system available to functionally analyze F. nucleatum proteins. Interestingly, F. nucleatum has a diverse landscape of structurally unique surface adhesins called Type 5c secreted trimeric autotransporter adhesins (TAAs), which are a family of proteins that are historically known for their contributions to bacterial pathogenesis. This dissertation encompasses the use of recombinant protein expression systems and newly developed gene deletion technology to provide a foundational understanding of the contribution of Type 5c secreted proteins in F. nucleatum pathogenesis. Our results show that the presence of TAAs on the surface of F. nucleatum contribute to the bacterium's ability to bind and invade human cells, establishing the need to characterize other F. nucleatum surface proteins. Additionally, our studies analyzed the proinflammatory landscape induced by F. nucleatum through the identification of specific cytokines that are being secreted during in vitro infections of human cells. Cytokine signaling is a critical aspect of the host cell immune response as it promotes the recruitment of immune cells to the site of infection for efficient clearance of bacterial pathogens. While it has been well established that F. nucleatum modulates the secretion of IL-8, our studies identified that the bacterium also promotes the secretion of CXCL1, which is an important signaling protein that promotes tumor metastases. Overall, the work provided in this dissertation has delivered the initial characterization of TAAs in F. nucleatum virulence, a framework for future studies of Type 5c secreted proteins in Fusobacterium pathogenesis, and the role of Fap2 and FadA in promoting pro-inflammatory and pro-metastatic signaling from colorectal cancer cells.
Master of Science in Life Sciences

A cavidade bucal é um habitat microbiano complexo que apresenta mais de 500 espécies bacterianas como componentes da microbiota. A saúde periodontal está estabelecida quando há equilíbrio entre os microrganismos patogênicos e o hospedeiro. O digluconato de clorexidina é um dos antimicrobianos bucais mais utilizados, no entanto, essa substância tem sido associada a alguns efeitos colaterais indesejáveis. Os óleos de copaíba e de melaleuca tem sido estudados como importantes fitoterápicos, devido aos seus diversos efeitos, entre eles ação antibacteriana. Partindo-se do princípio de que o óleo copaíba e de melaleuca possuem atividade antimicrobiana e de que não há dados suficientes na literatura utilizando esses fitoterápicos sobre Porphyromonas gingivalis e Fusobacterium nucleatum, foram preparados testes de Concentração Inibitória Mínima (CIM) e Concentração Bactericida Mínima (CBM) das bactérias Fusobacterium nucleatum (ATCC 25586) e Porphyromonas gingivalis (ATCC 3327) frente ao digluconato de clorexidina e aos óleos provindos de Copaifera officinalis e de Melaleuca alternifólia. Realizaram-se ainda testes para determinação de Concentração Subinibitória (CS) e ensaios para determinar a capacidade de autoagregação e coagregação dessas bactérias expostas às concentrações subinibitórias das soluções testadas. Como controles foram utilizados apenas meio de cultura e meio de cultura acrescido de Tween 80. Todos os óleos utilizados tiveram sua composição analisada por cromatografia gasosa acoplada à espectrometria de massa. O óleo de melaleuca, após identificação de sua composição, apresentou, respectivamente, os seguintes constituintes em maiores concentrações: terpin-4-ol, -terpineno, -terpineno, terpinoleno e 1,8-cineol. O óleo de copaíba apresentou como principais constituintes, respectivamente, trans-cariofileno, germacreno B, -humuleno, germacreno D e -copaeno. Os resultados obtidos como CIM para F.nucleatum foram semelhantes à CBM em todas as soluções testadas. Para a bactéria P.gingivalis, todas as soluções testadas inibiram o crescimento bacteriano, contudo, os resultados obtidos durante a determinação da CBM demonstraram que o óleo de copaíba foi bacteriostático. Todas as soluções testadas inibiram o processo de autoagregação e apenas o óleo de copaíba foi eficiente na inibição do processo de coagregação entre F.nucleatum e P.gingivalis. Esses dados sugerem que as três soluções testadas apresentam relevantes mudanças no desenvolvimento normal de P.gingivalis e F.nucleatum, bem como influenciam no processo de autoagregação de F.nucleatum. O óleo de copaíba demonstrou ter uma notável propriedade de inibir o processo de coagregação entre as bactérias testadas neste estudo.
The oral cavity is a complex microbial habitat that has more than 500 bacterial species as components of the microbiota. Periodontal health is established when there is equilibrium between pathogens and host. The chlorhexidine digluconate is one of the most commonly used oral antibiotics, however, this substance has been associated with some undesirable side effects. Copaiba and melaleuca oils have been studied as important herbal medicines because of their effects, including antibacterial action. Based on the principle that the copaiba oil and tea tree have an antimicrobial activity and that is no sufficient data in the literature using these herbal medicines against Porphyromonas gingivalis and Fusobacterium nucleatum, Minimum Inhibitory Concentration (MIC) and minimum bactericidal concentration (MBC) tests of Fusobacterium nucleatum (ATCC 25586) and Porphyromonas gingivalis (ATCC 3327) related to chlorhexidine digluconate and oils coming from Copaifera officinalis and Melaleuca alternifolia, were prepared. Assays were performed to determine the subinibitory concentration and the capacity of those bacteria to autoaggregation and coaggregation when exposed to subinibitory concentrations, previously tested. Medium and medium added Tween 80 were used as a control. All oils used had their composition analyzed by gas chromatography-mass spectrometry. The tea tree oil mainly chemical compounds were identified as terpin-4-ol, -terpinen, -terpinen, terpinolene and 1,8-cineole while copaiba oil presented as its main constituents trans-caryophyllene, germacrene B, -humulene, germacrene D and -copaene. The MIC results for F.nucleatum were similar to the CBM data in all solutions. For the bacterium P. gingivalis, all solutions tested inhibited bacterial growth, however, the results obtained during the determination of CBM showed that the copaiba oil was bacteriostatic. All solutions tested inhibited the autoaggregation process but only copaiba oil was effective in inhibiting the coaggregation between F.nucleatum and P. gingivalis. These data suggest that all the solutions tested in this study have relevant changes in the normal development of P.gingivalis and F.nucleatum as well in the influence of the autoaggregation process of F.nucleatum yet Copaiba oil also demonstrated to have remarkable properties to change coaggregation between the bacteria used in this study.

Orientador: Ana Lia Anbinder
Coorientadora: Liliana Scorzoni
Banca: Cristiane Yumi Koga Ito
Banca: Victor Angelo Martins Montalli
Resumo: A doença periodontal, afecção crônica inflamatória multifatorial, está entre as principais doenças bucais que afetam a população mundial. Entre as bactérias associadas à periodontite, estão Fusobacterium nucleatum e Aggregactibacter actinomycetemcomitans. Novas terapias adjuntas ao tratamento convencional têm sido propostas para a doença periodontal, entre elas o uso de probióticos. Porém, seu uso não está isento de riscos, e uma alternativa para minimizá-los é inativar os micro-organismos, mantendo suas propriedades benéficas, o que ocorre com os chamados paraprobióticos. Desse modo, são objetivos deste estudo avaliar os efeitos antimicrobianos de L. reuteri vivo, inativado pelo calor e seus produtos sobre F. nucleatum, A. actinomycetemcomitans e sobre as bactérias comensais, Streptococcus mitis e Streptococcus salivarius, além de estudar os efeitos da interação das preparações e periodontopatógenos em modelo de invertebrado. A atividade antimicrobiana in vitro foi avaliada associando-se as bactérias patogênicas ou comensais a L. reuteri vivo, inativado ou sobrenadante. Após interação, as bactérias foram cultivadas em meio seletivo para contagem de unidades formadoras de colônias (UFC). No estudo em Galleria mellonella, após a infecção com as bactérias patogênicas e as preparações de L. reuteri, foi avaliada a curva de sobrevivência e densidade hemocitária. Os dados foram analisados com o teste estatístico apropriado, ao nível de 5%. Após interação bacteriana in vitro, S. sa... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Periodontal disease, a chronic multifactorial inflammatory disease, is among the major oral diseases that affects the worldwide population. Among the bacteria associated with periodontitis are Fusobacterium nucleatum and Aggregactibacter actinomycetemcomitans. New therapies have been proposed for periodontal disease as adjunct to conventional treatment, including the use of probiotics. However, their use isn't risk-free and an alternative to that is the inactivation of the microorganisms, maintaining their beneficial properties, which occurs with the paraprobiotics. Thus, the objective of this study is to evaluate the antimicrobial effects of living and heat-killed L. reuteri, and its products on F. nucleatum, A. actinomycetemcomitans and on the commensal bacteria, Streptococcus mitis and Streptococcus salivarius, as well as to study the interaction of the preparations and periodontopathogens in an invertebrate model. In vitro antimicrobial activity was evaluated by associating the pathogenic or commensal bacteria to live, heat killed or L. reuteri supernatant. After interaction, the bacteria were cultured in a selective medium for colony-forming unit (CFU) count. In the study with Galleria mellonella, after infection with pathogenic bacteria and L. reuteri preparations, the survival curve and hemocyte density were evaluated. The data were analyzed with the appropriate statistical test at the 5% level. After bacterial interaction in vitro, S. salivarius reduced the number of ... (Complete abstract click electronic access below)
Mestre

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.

Orientador: Ana Cláudia Pavarina
Resumo: O objetivo deste estudo foi avaliar a eficácia da terapia fotodinâmica antimicrobiana associada (aPDT) ao metronidazol (MTZ) em biofilmes periodontopatogênicos. Para tal finalidade, foram realizadas as seguintes etapas: (1) determinação do tempo de adesão (24 e 48 horas) e formação de biofilme mono e duo-espécie (3, 5 e 7 dias) de Fusobacterium nucleatum (NCTC 11326) e Porphyromonas gingivalis (ATCC 33277); (2) aplicação da aPDT mediada por PDZ associada ao MTZ em biofilmes mono-espécie de F. nucleatum e P. gingivalis. Foram avaliadas diferentes concentrações do PDZ (50, 75 e 100 mg/L) e dose de luz de 50 J/cm2 (660nm). Após a aplicação da aPDT, os biofilmes foram incubados com diferentes concentrações do MTZ (MIC, 50x MIC e 100x MIC) por 24 horas. Os grupos controles positivos (L-F-) não receberam fotossensibilizador e não foram iluminados. A viabilidade dos microrganismos após os tratamentos foi avaliada por meio da contagem de UFC/ml. Os resultados demonstraram que o período de adesão de 24 horas, seguido de 5 dias de formação de biofilme foi satisfatório para a obtenção de biofilmes maduros mono-espécie. Para F. nucleatum, os resultados demonstraram que aPDT 75 mg/mL associado com MTZ 100x MIC e aPDT 100 mg/L associado com MTZ nas concentrações de 50x MIC e 100x MIC reduziu significativamente o número de UFC/mL, 2,99; 2,9 e 3,94 Log10 respectivamente. Para P. gingivalis, a redução mais significativa de UFC/mL foi obtida quando a associação de aPDT 100 mg/L e MTZ 100x MIC ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to evaluate the efficacy of metronidazole (MTZ) associated antimicrobial photodynamic therapy (aPDT) on periodontopathogenic biofilms. For this purpose, the following steps were performed: (1) determination of adhesion period (24 and 48 hours) and single and duo species biofilm formation (3, 5 and 7 days) of Fusobacterium nucleatum (NCTC 11326) and Porphyromonas gingivalis (ATCC 33277); (2) Photodithazine ® (PDZ)- mediated aPDT in association with MTZ in single-specie biofilms of F. nucleatum and P. gingivalis. Different concentrations of PDZ (50, 75 e 100 mg/L) and light dose of 50 J / cm2 (660nm) were evaluated. After application of aPDT, the biofilms were incubated with different concentrations of MTZ (MIC, 50x MIC and 100x MIC) for 24 hours. Positive control groups (L-F-) received no photosensitizer and were also not illuminated. The viability of the microorganisms after the treatments was evaluated by counting CFU/ml. The results demonstrated that the 24 hours adhesion period followed by 5 days of biofilm formation was satisfactory for obtaining a mature biofilm in single-specie. For F. nucleatum, the results demonstrated that 75 mg/L aPDT associated with MTZ 100x and 100 mg/mL aPDT associated with MTZ at 50x MIC and 100x MIC concentrations significantly reduced the number of CFU/mL, 2.99; 2.9 and 3.94 Log10 respectively. For P. gingivalis, the greatest reduction of CFU/mL was obtained when the association of aPDT 100 mg/L and MTZ 100x MIC was p... (Complete abstract click electronic access below)
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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.

The aim of this study was evaluate the gene expression of proinflammatory (RANKL, TNF- e IFN-) and regulatory (TGF- e IL-10) cytokines in response to experimental infection in Balb/c mice molars by microorganisms Fusobacterium nucleatum (ATCC 10953) and Enterococcus faecalis (ATCC 19433) in single and bi association. The animals were sacrificed after 10 and 20 days, the periapical tissues were collected and the PCR real time dosed the cytokine expression. It was observed that the single infection with F. nucleatum induced high expression, on the 10º day, of RANKL and TNF- and this response modulation was due to IL-10. E. faecalis caused high expression of IFN- at 20º day, but this modulation in RANKL e TNF-expression was independent of IL-10 e TGF-. The bi association (F. nucleatum e E. faecalis) encouraged high expression of RANKL, TNF- e IFN-, on the 10º day, would be modulated by TGF- increased expression. It can be concluded that, in this model, gene expression of proinflammatory cytokines prevails in earlier periods of periapical changes induction with concomitant decrease in the late periods, and this is due to the regulatory cytokines IL-10 e TGF- modulation, but in a way infection-specific.
O objetivo deste estudo foi avaliar a expressão gênica das citocinas pró-inflamatórias (RANKL, TNF- e IFN-) e regulatórias (TGF- e IL-10) em resposta à infecção experimental em molares de camundongos Balb/c com os microrganismos Fusobacterium nucleatum (ATCC 10953) e Enterococcus faecalis (ATCC 19433), em mono ou em bi-associação. Os animais foram sacrificados após 10 e 20 dias, e os tecidos periapicais coletados, dosando-se a presença das citocinas por PCR em tempo real. Observou-se que a mono-infecção com o F. nucleatum induziu, no 10º dia, alta expressão de RANKL e TNF- e que a modulação dessa resposta se deveu à IL-10. O E. faecalis provocou uma alta expressão de IFN- no 20º dia, mas essa modulação observada na expressão do RANKL e TNF- foi independente da IL-10 e TGF-. A bi-associação (F. nucleatum e E. faecalis) estimulou uma alta expressão das citocinas RANKL, TNF- e IFN-, no 10º dia, que seria modulada pela presença aumentada do TGF-. Pode-se concluir que, neste modelo, a expressão gênica das citocinas pró-inflamatórias prevalece nos períodos iniciais de indução das alterações periapicais com concomitante redução no período tardio e isto se deve à modulação promovida pelas citocinas regulatórias IL-10 e TGF-, mas de uma maneira infecção-específica.

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 Gram-negative, anaerobic bacterium that is a member of the human oral microbiota. Although it is a normal resident of the mouth, it is associated with a number of human diseases including: sepsis, inflammatory bowel disease (IBD), and colorectal cancer (CRC). Despite the important association of F. nucleatum with human health and disease, remarkably little is known about the molecular mechanisms underlying these infections. This knowledge gap can, in part, be attributed to a lack of molecular tools and experimental workflows. Creating the genetic tools to fill this knowledge gap is an imperative undertaking for the future development of treatments for diseases involving F. nucleatum. Previous work in the field has assigned functions to just a handful of Fusobacterium proteins (Fap2, FadA), and only two of those proteins have a well-defined role in the host-pathogen relationship. This dissertation contains work that lays the molecular and genetic foundation for future studies involving F. nucleatum by creating a unique gene deletion system while simultaneously establishing broadly applicable experimental workflows and molecular tools to study initial bacterial attachment and invasion processes crucial to Fusobacterium virulence. Marker-less gene deletions confirm the importance of Fap2 in host-cell attachment and invasion and suggest a lesser role in invasion for FadA, representing a significant revision to the Fusobacterium-host relationship. Also, our system allows for the overexpression and purification of virulence factors directly from Fusobacterium for the first time. This permits us to study aspects of Fusobacterium protein biology that were previously impossible and will provide further insights into the nature of Fusobacterium virulence. A custom suite of molecular tools was also developed to facilitate recombinant expression of these proteins in general laboratory settings using simple E. coli protein expression systems. We have used these new technologies to express and purify a number of potential Fusobacterium virulence factors as detailed in this dissertation. Also contained in this dissertation is the application of these breakthroughs to probe the function of a novel F. nucleatum outer membrane phospholipase, FplA. Phospholipases are important virulence factors in a number of well-studied human pathogens including Pseudomonas aeruginosa and Legionella pneumophila, where they interfere with host cellular signaling processes to increase intracellular bacterial survival. Our data show that FplA is a Class A1 phospholipase (PLA1) with robust catalytic activity capable of binding to and cleaving a number of lipid types. Additionally, we show that it has the ability to bind to important host signaling lipids including phosphatidylinositol 3, 5-bisphosphate and phosphatidylinositol 3, 4, 5-triphosphate. These data suggest FplA may play a role in manipulating the intracellular processes of host cells. Taken together, work in this dissertation provides tools and experimental frameworks for the future study of F. nucleatum pathogenesis while identifying and initially characterizing a new, potentially significant, virulence factor in FplA.
Doctor of Philosophy

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.

Dans ce projet de recherche, les propriétés antibactériennes et le potentiel anti-destruction tissulaire des polyphénols du thé vert, plus particulièrement l’épigallocatéchine-gallate (EGCG), ont été évalués. Dans un premier temps, l’effet antibactérien d’un extrait de thé vert et de l’EGCG a été déterminé sur trois bactéries parodontopathogènes d’importance, soit Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans et Fusobacterium nucleatum. Les concentrations minimales inhibitrices se sont avérées être entre 1000 et 62,5 µg/ml. De plus, des effets synergiques et additifs des polyphénols du thé vert ont été observés lorsqu’utilisés en association avec le métronidazole ou la tétracycline, des antibiotiques couramment utilisés en thérapie parodontale. Dans un deuxième temps, un modèle de co-culture constitué de fibroblastes gingivaux intégrés dans un gel de collagène et recouvert de macrophages a été utilisé pour évaluer la capacité des polyphénols du thé vert à inhiber la sécrétion de métalloprotéinases matricielles (MMPs), notamment les MMP-3, MMP-8 et MMP-9. Il a été démontré que les polyphénols du thé vert atténuent la sécrétion des MMPs par le modèle de co-culture. En conclusion, les résultats de cette étude ont apporté des évidences supportant le potentiel des polyphénols du thé vert en vue d’une utilisation préventive et thérapeutique pour le contrôle des maladies parodontales.

La parodontite est une infection polymicrobienne qui entraîne une inflammation du parodonte et provoque une destruction irréversible des tissus de soutien de la dent. Le but de cette étude était d'évaluer les concentrations des cytokines IL-18, IL-1β, IL-10, TNFα ainsi que celles des récepteurs Toll de type 2 (Toll-like receptor 2, TLR2) et 4 (TLR4) solubles dans le fluide créviculaire gingivale (FCG) et la salive d'une cohorte de patients atteints de parodontite. Ces concentrations ont été corrélées avec les paramètres cliniques de la parodontite et la quantité des bactéries Porphyromonas gingivalis, Treponema denticola et Fusobacterium nucleatum retrouvées chez les participants à l'étude. Les résultats obtenus ont révélé que les taux d'IL-18, d'IL-1β et de TLR4 dans le FCG sont plus élevés chez les sujets atteints de parodontite par rapport à ceux exempts de la maladie et que la sévérité de la maladie parodontale est associée à des concentrations élevées d'IL-1β et de TLR4 chez les sujets malades.

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.
Tesis

En las últimas décadas ha habido grandes avances en el conocimiento de la etiología y la patogenia de las lesiones pulpares y periapicales. Actualmente se sabe que los microorganismos juegan un papel principal en la enfermedad inflamatoria de la pulpa y tejidos periapicales. Antiguamente las técnicas para identificar los microorganismos no eran las mejores, especialmente para identificar los anaerobios, por lo que se creía que la presencia de microorganismos aerobios era mayor que la de anaerobios, ahora gracias a las nuevas técnicas de cultivo e identificación se puede afirmar que la flora en los conductos radiculares es polimicrobiana y que los microorganismos más prevalentes son lo anaerobios. Es por esto que el tratamiento a tiempo y de manera adecuada lleva a la eliminación o disminución de los microorganismos de la cámara pulpar y conductos radiculares infectados, para así poder lograr una limpieza y desinfección que culmine en una evolución satisfactoria. En nuestro país actualmente existe un alto índice de niños que padecen de caries dental y de estas un gran número de piezas dentarias ya presentan lesiones pulpares, una de ella es la necrosis pulpar, por esto en la presente investigación identificamos a uno de los principales causantes de esta, que es el Fusobacterium nucleatum y la sensibilidad que este presenta a algunos de los irrigantes más usados en la práctica odontológica, esto nos ayudará a poder planear un eficaz tratamiento, evitando la perdida de estas piezas dentarias.
Tesis

In der vorliegenden Arbeit sollten die in der veterinärmedizinischen Literatur bisher diskutierten Ursachen für LJD bei Makropoden hinsichtlich ihrer tatsächlichen Bedeutung abgeklärt und die Eignung einer formalininaktivierten, bestandsspezifischen Adsorbatvakzine zur Prophylaxe von LJD getestet werden. Da LJD eine parodontale Erkrankung darstellt, wurden auch die für Entstehung einer humanen Parodontitis prädisponierenden Faktoren mit in die Untersuchung einbezogen. Es wurden Tupferproben zur bakteriologischen Untersuchung von insgesamt 15 gesunden und 11 an LJD erkrankten Kängurus entnommen. Dabei konnten gramnegative Anaerobier bei allen Tieren isoliert werden. Fusobacterium nucleatum wurde in 82% der von an LJD erkrankten und nur in 33% der von gesunden Tieren entnommenen Tupferproben nachgewiesen, womit sich ein signifikanter Zusammenhang (P < 0,05) zwischen diesem Erreger und LJD ergab. Weitere überwiegend bei erkrankten Makropoden nachgewiesene Anaerobier stellten Prevotella oris/oralis (bei 73% der LJD-Fälle und bei 40% der gesunden Tiere) sowie Capnocytophaga spp. (45% vs. 13%) dar. Bacteroides spp. und Porphyromonas gingivalis wurden – wenn auch nur mit 3 bzw. 2 Nachweisen – ausschließlich bei kranken Tieren isoliert. Fusobacterium necrophorum wurde jeweils in 27% der Kängurus gefunden und spielte damit in dieser Studie keine Rolle für die Entstehung von LJD. In Übereinstimmung mit der Literatur konnten Moraxella spp. ausschließlich bei gesunden Makropoden isoliert werden. Vertreter dieser Gattung gehören damit offensichtlich zur normalen Maulflora der Kängurus. Für die Zoos in Halle und Leipzig wurde eine formalininaktivierte, bestandsspezifische Adsorbatvakzine gegen die bei einem an LJD erkrankten Känguru des jeweiligen Bestandes isolierten gramnegativen Anaerobier hergestellt. 7 Tiere (2 Rote Riesenkängurus, 5 Bennettwallabies) des Leipziger Zoos und 6 Bennettkängurus des Zoos in Halle wurden geimpft, wobei Auffrischungsimpfungen nach 4 bzw. 8 Wochen und nach 6 bzw. 12 Monaten erfolgten. Die spezifischen AK gegen das Prüfantigen Fusobacterium necrophorum wurden im SLA bestimmt. Es konnte keine Erhöhung der AK-Titer induziert werden und auch die Todesrate infolge von LJD senkte sich während des Untersuchungszeitraumes von 42 Monaten in den beiden Zoos nicht. Die höchsten AK-Level (1:512 bis 1:2048) ließen sich im Serum von natürlich infizierten und letztendlich tödlich erkrankten Bennettwallabies des Zoos in Hoyerswerda feststellen. Der Nachweis von AK-Titern im Serum von nicht geimpften Jungtieren lässt vermuten, dass AK via Kolostrum oder Dottersackplazenta auf die Jungtiere übertragen werden. Die Untersuchungen hinsichtlich der Fütterung zeigten, dass im Zoo Leipzig eine azidotische Stoffwechsellage induziert wurde, was sich bei den Leipziger Bennettkängurus in einem mit 7,53 signifikant niedrigeren Vormagen-pH-Wert im Vergleich zu den Hallenser und Auer Tieren (8,25 und 8,38) offenbarte. Dies schlug sich auch in erhöhten K-, Cholesterol- und -Amylasewerten im Serum der Leipziger Wallabies nieder, womit gezeigt werden konnte, dass sich diese Parameter offenbar auch bei Makropoden zur Diagnostik einer chronischen Azidose eignen. Die Versorgung der Bennettkängurus in Magdeburg und Halle mit Ca und P war zwar nicht ausreichend, spiegelte sich aber nicht in veränderten Blutwerten dieser Mengenelemente wider. Die Aktivität der AP nimmt mit zunehmenden Alter ähnlich wie bei anderen Tierarten ab. Ihre negative Korrelation mit dem Alter der Tiere war dabei hochsignifikant (P < 0,001, r = 0,77 bzw. 0,62). Beim direkten Vergleich gesunder mit an LJD erkrankten Tieren konnte weder eine Störung im Ca/P-Stoffwechsel noch eine Azidose in Verbindung zu LJD gebracht werden. In allen Zoos erfolgte eine Überversorgung mit Vitamin A, wobei die Bedarfswerte für Schaflämmer um das 3,5fache bis 41fache übertroffen wurden. Den Bedarfswerten am nächsten lagen die Versorgungswerte der Bennettkängurus vom TP Aue und der Östlichen Grauen Riesenkängurus vom Zoo Magdeburg, beides Bestände ohne LJD. Die ermittelten Retinolplasmakonzentrationen standen in keiner Beziehung zu den Vitamin-A-Gehalten im Futter, was darauf hindeutet, dass sich Retinolbestimmungen im Blutplasma ebenso wie bei anderen Tierarten nur in extremsten defizitären Situationen zur Einschätzung des Vitamin-A-Status eignen. Ob eine Hypervitaminose A für die Entstehung von LJD tatsächlich eine Rolle spielt, muss in zukünftigen Arbeiten unter Einbeziehung von Retinolesterbestimmungen in der Leber abgeklärt werden. Die Glukosewerte lagen mit 8,57 mmol/l (M. rufus) bzw. 6,51 mmol/l (M. rufogriseus) über den bisher bekannten Werten aus der Literatur. Da die Werte bei an LJD erkrankten Kängurus niedriger waren als bei gesunden Tieren, kann ein Diabetes mellitus als Ursache für LJD ausgeschlossen werden. Weder die Durchsicht von 144 Sektionsprotokollen noch die Bestimmung der Kreatinin- und Harnstoffkonzentration im Serum von an LJD erkrankten Tieren ließen einen Zusammenhang zwischen Erkrankungen der Nieren und LJD erkennen. 30 Tiere verendeten an LJD, wovon 20% auch an den Nieren erkrankt waren. Allerdings wiesen auch 16,7% der anderweitig gestorbenen Kängurus eine Nierenerkrankung auf. Die Serumkonzentrationen von Harnstoff bzw. Kreatinin der an LJD erkrankten Makropoden unterschieden sich nicht von den für die gesunden Roten Riesenkängurus (7,40 mmol bzw. 114 mmol/l) und Bennettwallabies (7,81 mmol/l bzw. 86 mmol/l) ermittelten Werten. Insgesamt 184 Sera von 107 Kängurus wurden auf AK gegen MaHV-1 und MaHV-2 mittels Neutralisationtest geprüft. Während 94,4% bzw. 97,2% der Roten Riesenkängurus serologisch positiv für MaHV-1 bzw. MaHV-2 waren, reagierten von den 71 überprüften Bennettkängurus nur 4 bzw. 3 Tiere positiv. Unter den Wallabies befanden sich auch 21 an LJD erkrankte Tiere, wovon lediglich 2 Tiere gegen MaHV-1 und 1 Tier gegen MaHV-2 eine Serokonversion zeigten. Die AK-Titer der Roten Riesenkängurus ließen keine Unterschiede zwischen gesunden und an LJD leidenden Tieren zu und die entnommenen Serumpaarproben von 5 zum Zeitpunkt der Blutentnahme an LJD leidenden Riesenkängurus zeigten kein einheitliches Verhalten im Sinne einer Serokonversion. Somit ließ sich der Verdacht, dass die Reaktivierung latenter Herpesinfektionen die Ursache für LJD sein könnte, nicht bestätigen. Im Ergebnis der vorliegenden Studie und im Zusammenhang mit den Angaben aus der Literatur stellt sich LJD primär als eine Infektion mit gramnegativen Anaerobiern dar, wovon Fusobacterium nucleatum, Bacteroides spp., Prophyromonas gingivalis und Fusobacterium necrophorum, Biovar A die größte Bedeutung haben dürften. Den Abschluss der Arbeit bilden Empfehlungen für die Haltung von Kängurus in zoologischen Einrichtungen und für die Therapie von LJD. Im Anhang finden sich Röntgenaufnahmen und Photographien von erkrankten und gesunden Makropoden
The aim of this thesis was the investigation of the aetiology of Lumpy Jaw Disease (LJD) in macropods concentrating specifically on the causes of the diseases in current veterinary medicine literature and to evaluate the use of a group-specific Al(OH)3-adjuvanted, formalin-inactivated whole-cell vaccine for the control of LJD in kangaroos kept in zoos. LJD is regarded as periodontal disease, therefore the risk factors for the development of human periodontitis were also included in this study. The oral flora from 15 healthy macropods and 11 animals suffering from LJD was isolated. At least one anaerobic gram-negative bacterial species was found in swabs of each macropod. The occurrence of Fusobacterium nucleatum was associated with LJD (P < 0.05) by detecting this bacterium in 82% of the kangaroos suffering from LJD compared to only in 33% of the healthy animals. Prevotella oris/oralis and Capnocytophaga spp. were also predominantly found in diseased animals in comparison with healthy macropods (73% vs. 40% and 45% vs. 13% respectively). Bacteroides spp. and Porphyromonas gingivalis were isolated in only 3 and 2 kangaroos suffering from LJD, respectively. Contrary to previously published studies about LJD Fusobacterium necrophorum was not associated with LJD, as this anaerobe was detected in only 27% of the diseased as well as healthy macropods. Moraxella spp. seem to be a part of the normal oral flora of macropods and was found exclusively in healthy animals. 11 Red-necked Wallabies (Macropus rufogriseus) and 2 Red Kangaroos (Macropus rufus) were immunized with a group-specific Al(OH)3-adjuvanted, formalin-inactivated whole-cell vaccine containing previously in a kangaroo suffering from LJD isolated gramnegative anaerobs. The kangaroos were re-vaccinated after 1, 2, 6 and 12 months. Blood was collected from each animal at the same time. Antibodies were titrated against Fusobacterium necrophorum in an agglutination assay. The vaccine failed to induce increased levels of antibodies as well as to protect wallabies and kangaroos against LJD. As the highest antibody titres were detected in most severely diseased wallabies kept in the Hoyerswerda zoo, the protective role of the humoral immune response in LJD seems to be doubtful. The finding of detectable levels of antibodies in unvaccinated joeys supports the theory, that there is a transmission of antibodies from the mother to the offspring via colostrum or yolk-sac placenta. The diet of the Red-necked Wallabies in one zoo has induced an acidosis: The pH of the forestomach fluid collected by probang was lower in the animals of this zoo (pH = 7.53) than in the wallabies of two other zoos (pH = 8.25 and 8.38, respectively). Potassium, cholesterol and -amylase were also higher in the blood of the animals of this zoo in comparison to the wallabies of the two other ones, hence these blood values seem to be helpful for the diagnosis of chronic acidosis in macropods. There was a calcium and phosphor deficiency in the nutrition of the wallabies in two zoos, but the blood concentration of both of these minerals was not changed. The activity of the ALP correlated negative with the age of the Bennett`s Wallabies (P < 0.001, r = -.77 and r = -.62 respectively, depending on the instruments). All of the above mentioned blood values showed no differences between healthy and diseased animals and could so far not support the assumption, that an imbalance in Ca and P metabolism or an acidosis are important factors for LJD. The macropods of all investigated zoos were fed on a diet rich in vitamin A ranging from the 3.5 to the 41fold requirement for lambs. The vitamin A content of the diets for the 2 collections without a history of LJD was the lowest in this study. These results raised the point, that a hypervitaminosis A could be a more predisposing factor for LJD than a vitamin A deficiency. Due to the fact the plasma retinol concentration was independent from the vitamin A content of the diet and so not helpful in diagnosis of a vitamin A deficiency or toxicity, further investigations regarding the role of vitamin A in the aetiopathogenesis of LJD should include measurements of the liver tissue content of retinol esters. The glucose plasma concentration of the healthy Red Kangaroos (8.57 mmol/l) as well as the Red-necked Wallabies (6.51 mmol/l) was higher than previously published values for macropods, but also higher than the results of the diseased animals in this study. Therefore diabetes mellitus can be ruled out as an underlying factor for LJD. The analysis of 144 pathological records showed, that 30 animals died because of LJD, 20% of them and 16.7% of the other 114 macropods had a concurrent kidney disease. The urea and creatinin concentration in serum samples of healthy animals was not higher than the values of diseased animals. In conclusion, these results suggest kidney diseases are not important for the development of LJD. Altogether 184 sera collected from 107 kangaroos were tested for antibodies against MaHV-1 and MaHV-2 using a neutralisation assay. The prevalence of the MaHV-1- as well as MaHV-2-antibodies was high among the Red Kangaroos (94.4% and 97.2% respectively), but low among the Red-necked Wallabies (5.6% and 4.2% respectively). Seroconversion for MaHV-1 was seen in 2 out of 21 wallabies suffering from LJD, only 1 of these animals also had antibodies against MaHV-2. The antibody-titres against both of the macropodid herpes viruses also did not differ between Red Kangaroos with and without LJD, therefore a reactivation of a latent herpesvirus infection does not appear to be causative for LJD. In summary, considering the results of this study and previously published literature LJD is an infectious disease caused by gramnegative anaerobic bacteria with Fusobacterium nucleatum, Bacteroides spp., Porphyromonas gingivalis and Fusobacterium necrophorum subsp. necrophorum being of most significance. Recommendations concerning the keeping of kangaroos in captivity and the management of LJD are listed in the conclusion of this thesis. Some radiographs and photos of diseased and healthy kangaroos are attached

Crystallization that occurs during or after a strong shear is important in polymer processing due to its strong effect on product properties and production rate. This study addresses several major gaps in our knowledge of this phenomenon by investigating shear-induced crystallization of nucleated isotactic polypropylenes by simultaneous measurement of light intensity and rheology using a sliding plate rheometer at high, uniform shear rates. An optical fiber probe was devised for the light intensity measurement. For the conditions studied, both measurements were found equally able to detect nascent crystalline structures, but light intensity is more suitable for monitoring changes during the early stages, whereas rheology is more useful for tracking the late kinetics. The relative influence of a melt-insensitive nucleating agent, molecular weight, shear rate, and strain were studied under isothermal, low-supercooling conditions following brief shearing. In contrast to that in quiescent crystallization, the nucleation pathway of nucleated polymers after strong shear was found to be governed not by the nucleating agent but by the molecular weight. The primary effect of shear was confirmed to be in inducing nucleation and is much weaker in changing growth kinetics. Shear and nucleating agent both shorten the induction time, but the effects were found not to be additive. With increasing shear rate or strain, crystallization was found to first accelerate as a result of the increase in the number of point-like nuclei, then saturate due to either slip or consumption of high-molecular weight components for the creation of nuclei, and finally accelerate again at the onset of the transition from spherulitic to highly oriented morphology. Both a critical shear rate and a critical strain are necessary to initiate this morphological transition. The product of shear rate and strain was found useful for describing the acceleration in crystallization associated with the increase
La cristallisation sous ou après un cisaillement fort est importante dans les procédés de mise en forme des polymères dus à ses effets significatifs sur les propriétés du produit et sur le taux de production. Cette étude traite de plusieurs importantes lacunes dans notre connaissance de ce phénomène en étudiant la cristallisation induite par cisaillement des polypropylènes isotactiques contenant un agent nucléant par une mesure simultanée de l'intensité lumineuse et de la rhéologie en utilisant un rhéomètre à plaques parallèles à des taux de cisaillement élevés et homogènes. Une sonde à fibres optiques a été conçue pour mesurer l'intensité lumineuse. Pour les conditions étudiées, ces deux mesures se sont avérées être aussi bien en mesure de détecter des structures cristallines naissantes, mais l'intensité lumineuse est mieux adaptée pour surveiller les changements au cours des premiers stades de la cristallisation, considérant que la rhéologie est plus utile pour en suivre les derniers stades. L'influence relative d'un agent nucléant ne réagissant pas à la fusion, le poids moléculaire, le taux et la déformation du cisaillement ont été étudiés en conditions isothermes avec faible surfusion après un cisaillement bref. Si on la compare à une cristallisation en condition statique, la voie de la germination des polymères nucléés suite à un fort cisaillement est apparue être régie non pas par l'agent nucléant, mais par le poids moléculaire. Le principal effet du cisaillement a été confirmé être présent durant la germination induite et est beaucoup plus faible en changeant la cinétique de croissance. Le cisaillement et l'agent nucléant ont à la fois réduit le temps d'induction, mais les effets se sont révélés ne pas être cumulatifs. Avec l'augmentation du taux de cisaillement ou de la déformation, la cristallisation s'est avérée tout d'abord accélérée comme une conséquence de l'augmentation du

The effect of silica on the crystallization and melting behavior of a highly isotactic, well characterized isotactic polystyrene (i-PS) have been investigated. The origins of the various endotherms obtained upon heating have been defined by partial scanning experiments and by a study of the effect of heating rate using differential scanning calorimetry (DSC). The presence of 1 part silica in 100 parts polymer (1 pph) decreases the maximum degree of crystallinity considerably but has a minimal effect on the rate of crystallization. Analysis by the Avrami method shows that the silica does not affect the overall rate of crystallization significantly. The decrease in the crystallinity indicates that silica affects the level of secondary crystallization, thus the crystal perfection.
The surface morphologies and growth rates of i-PS spherulites, as studied by photomicroscopy, were not affected by 1 pph of silica. The experimental data were fitted to a modified form of the Hoffman-Lauritzen equation.
The effect of silica on spherulite growth rates and surface morphologies of isotactic poly(propylene oxide) (i-PPO) have also been investigated by optical microscopy. Two distinct i-PPO samples of different molecular weights were used, each of which was highly isotactic. The addition of silica has a pronounced effect on the morphology of the spherulites, producing dendritic type morphology. Upon step-crystallization, the spherulites exhibited mixed morphologies, i.e., fibrillar and ringed. Silica depresses the spherulite growth rates throughout the entire temperature range. The effects were more profound as the quantity of filler increased. The growth rate-temperature behavior was analysed in terms of the classical Hoffman-Lauritzen equation and a modified version to take into account the polymer-filler interaction.

Within the course of this master thesis project, subcooled nucleate boiling in a vertical pipe has been modeled using CFD. The modeling has been carried out within the OpenFOAM framework and a two-phase Eulerian approach has been chosen. The code can be used to predict the distribution of the local ow parameters, i.e.the void fraction, the bubble diameter, the velocity of both liquid and gas, the turbulent intensity as well as the liquid temperature. Special attention has been devoted to the phenomena which govern the void fraction distribution in the radial direction. Two di erent solvers have been implemented and the simulations have been performed in two dimensions. Firstly, isothermal turbulent bubbly ow is mechanistically modeled in a solver named myTwoPhaseEulerFoa-mAdiabatic. The conservation equations of mass and momentum are solved for the two phases, taking special care in the modeling of the interfacial forces. The turbulence phenomena are described by a classical k- model in combination with standard wall functions for the near-wall treatment. Furthermore, an interfacial area concentration equation is solved and two di erent models for its sink- and source terms (corresponding to bubble coalesence and bubble breakup) have been investigated. Secondly, a solver named myTwoPhaseEulerFoamBoiling has been developed based on the rst solver in order to model a heated wall leading to subcooled nucleate boiling and subsequent condensation in the subcooled liquid. Additional terms accounting for the phase change have been included in the mass and momentum conservation equations as well as in the interfacial area equation. Assuming the gas phase being at saturation conditions, only one energy equation for the liquid phase needs to be solved. The adiabatic solver has been validated against the DEDALE experiment and the simulation results showed satisfactory agreement with the measured data. The predictions obtained from myTwoPhaseEulerFoam-Boiling have been compared to the DEBORA experimental data base. They are qualitatively similar but rather high quantitative discrepancies exist. Grid dependence tests revealed that the latter solver depends on the near-wall grid resolution, a yet unresolved issue related to the application of the wall heat ux as the boundary condition. However, the results were shown to be insensitive to small variations in the applied inlet conditions.

The analysis of the different types of cells in blood is routinely used in today's medical practice to give an indication of a person's state of health. Many imaging systems and algorithms have been developed over the last 30 years in an attempt to automate this process. Some of these systems can now distinguish the difference between normal and abnormal cells but the differentiation among the various types of abnormal cells is still undergoing active research. A new system, the Cell Analyzer Imaging System, has been developed to acquire and process images from a microscope. In this work, some new algorithms have been developed using this system to detect and segment nucleated cells in Wright's stained blood smears for classification and sub-classification of the normal and abnormal cell types. The initial steps are to obtain high quality images by greatly reducing noise as well as by correcting distortions, aberrations and shading effects present in the acquired images. Spectral information from the images is then utilized to detect and segment nucleated cells from the rest of the scene (non-nucleated cells and background). All nucleated cells as well as those which are just touching are selected and separated into individual cells. The resulting single cells are further segmented into the regions of nucleus and cytoplasm. Simple features are then extracted from the segmented cells and these features are compared to determine if any clustering of a particular class of cell exists. Results show that these algorithms can detect, segment and classify different types of normal and abnormal nucleated blood cells. The major errors in segmentation accounts for approximately 6% of the cells analyzed.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

Deposition of protein fibers with a characteristic cross-β sheet structure is the molecular marker associated with human disorders ranging from Alzheimer's disease to type II diabetes and spongiform encephalopathy. Given the large number of non-disease related proteins and peptides that have been shown to form amyloid fibrils in vitro, it has been suggested that amyloid fibril formation represents a generic protein phase transition. In the last two decades it has become clear that the same protein/peptide can assemble into distinct morphologically and structurally amyloid aggregates depending on the solution conditions. Moreover, recent studies have shown that the early stage, oligomeric amyloid assemblies are the main culprit in vivo. We have investigated the amyloid assemblies formed under denaturing conditions for Hen Egg White Lysozyme (HewL) whose human homologue is directly implicated in hereditary non-neuropathic systemic amyloidosis. Our early investigations showed that HewL can aggregate via at least two distinct assembly pathways depending on solution ionic strength at fixed pH, temperature, and protein concentration. By combining Dynamic Light Scattering (DLS), Static Light Scattering (SLS) and Atomic Force Microscopy (AFM) we showed that at low ionic strength, the pathway is characterized by the nucleation and growth of long (several micron), rigid fibrils (RF) via monomers assembly. A second, high ionic strength pathway is characterized by the rapid assembly of monomers into globular oligomers that further polymerize into curvilinear fibrils (aO/CF). At NaCl concentrations above 400 mM, aggregation resulted in precipitate formation. Next, we used Foureir Transform Infrared spectroscopy (FTIR) and an amyloid-specific dye, Thioflavin T (ThT), to show that both RF and (a)O/CF are amyloidogenic species, but they have detectable structural differences. Moreover, we have determined that each assembly pathway has unique SLS, DLS, FTIR and ThT response signatures that help determine the assembly type prior to AFM imaging of aggregates. Taking advantage of the morphological, structural and kinetic signatures for the two distinct HewL amyloid aggregates I mapped out their amyloid aggregates phase diagram spanning over two orders of magnitude in protein concentration and from 50 to 800 mM NaCl in ionic strength. This is the most complete phase diagram for amyloid aggregates of a given protein up to date. The phase diagram has three distinct regions delineated by sharp boundaries. The RF- aO/CF was called Critical Oligomer Concentration, and we commonly refer to “above the COC” as the region were aO/CF are kinetically favored.. In the region of low salt/high protein concentrations, RF were the only amyloid species to nucleate and grow. As both salt and protein concentrations increase, aO/CF become the kinetically favored species, and RF nucleate and grow after several days of incubation. At high protein and high salt concentrations, aO/CF form very fast and eventually lose solubility forming a precipitate (Ppt). Cross-seeding experiments showed that RF is the thermodynamically stable aggregate phase, while the O/CF are the metastable species. Finally, we used the phase diagram to design experiments that would allow us to reveal the RF nucleation mechanism in presence of aO/CF. RF nucleation above the COC can undergo either via internal restructuring of aO/CF (NCC) or through a random coalescence of monomers into a nucleus (NP). The experimental results obtained so far strongly indicate that RF nucleate via NP mechanism both below and above the COC.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 1992.
Thesis Advisor: Kelleher, M. D. "September 1992." Description based on title screen as viewed on April 16, 2009. Includes bibliographical references (p. 92). Also available in print.

Os estudos relacionados ao coração têm sido realizados ao longo dos anos de forma bastante comum, tendo em vista a grande importância que este órgão tem na medicina. Problemas relacionados ao mesmo são uma das principais causas de mortes e internações no Brasil e no mundo, por causa disso, avanços no que diz respeito a inovações tecnológicas e novas metodologias de estudo tem sido propostas cada vez com mais freqüência, e, o suíno tem se mostrado um modelo bastante útil, pois apresenta diversas similaridades em relação ao ser humano.O uso da estereologia se encaixa nesta nova busca, pois através de suas ferramentas nos proporciona excelentes resultados a níveis de mensuração, e quantificação de estruturas microscópicas. O objetivo desse estudo foi obter valores referentes à quantificação de cardiomiócitos do ventrículo esquerdo em suínos normais. Utilizaram-se 3 suínos fêmeas pesando em torno de 25kg, os quais após serem eutanasiados tiveram o coração retirado e suas câmaras separadas. Em seguida lâminas referentes a esse material foram preparadas e fotografadas, para serem analizadas utilizando-se o disector e o nucleator como ferramentas estereologicas. Os resultados nos mostram que a média de peso do ventrículo esquerdo dos animais foi de 660 mg, o volume médio dos cardiomiócitos foi de 16.32 µm³, a média do numero de cardiomiócitos foi de 3,91x108, enquanto que a média do volume de cardiomiócitos que ocupam o ventrículo esquerdo foi de 3,32x106.
Investigations involving the heart have been largely carried out all over the years due to its importance in medicine. Heart diseases are the one of the major causes of deaths and hospitalizations in Brazil and worldwide. In this context, technological innovations and progresses in methodological investigation have been frequently proposed; Swine has been shown as a useful model due to similarities to human. The application of stereological tools for investigations in the morphology of the heart has been intensely applied based on the reliability on the results for measuring and quantification. This study aimed to evaluate morphological and quantitative aspects of cardiomyocytes in the left ventricle in healthy swine. Three female swine, averaging 25 kg were euthanasiated and have the hearth chambers separated. Left ventricles were fixed and slides obtained. Images were acquired and analyzed by dissector and nucleator. The results showed us that the average weight of the left ventricle of the animals was 660 mg, the mean volume of cardiomyocytes was 16:32 µm3, the average number of cardiomyocytes was 3.91 x108, while the average volume of cardiomyocytes that occupy the left ventricle was 3.32 x106.

Thesis (Ph. D.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

This thesis discusses the production and use of laser-machined boiling grids that provide controlled nucleate boiling and enhanced heat transfer characteristics for application primarily to IC engine cooling systems. The surface features of heated plates are known to have a significant effect on nucleate boiling heat transfer and bubble growth dynamics. Nucleate boiling starts from discrete bubbles that form on surface imperfections, such as cavities or scratches. The gas or vapours trapped in these imperfections serve as nuclei for the bubbles. After inception, the bubbles grow to a certain size and depart from the surface. The bubble departure process significantly increases heat transfer rates compared to pure convection. In this work, special heated surfaces were manufactured by laser machining cavities into polished aluminium plates. This was accomplished with an Nd:YAG laser system, which allowed drilling of cavities of a known diameter. The size range of cavities was 25 to 300 micrometers. The resulting nucleate pool boiling was analysed using a high-speed imaging system comprising an infrared laser and high resolution CCD camera. This system was operated up to a 2 kHz frame rate and digital image processing allowed bubbles to be analysed statistically in terms of departure diameter, departure frequency, growth rate, shape and velocity. Data were obtained for heat fluxes up to 150 kW.m'2. Bubble measurements were obtained working with water at atmospheric pressure. The surface cavity diameters were selected to control the temperature at which vapour bubbles started to grow on the surface. The selected size and spacing of the cavities was also explored to provide optimal heat transfer. Insights into the interaction and interseeding mechanism were obtained. The research has demonstrated that nucleate boiling can be controlled by optimally sized and spaced laser-machined cavities in heated metal surfaces.

"The importance of two-phase heat transfer for thermal management of aerospace avionic systems has become increasingly important as these systems have become miniaturized. Embedded active cooling systems are used to remove heat from processors and other electronic components and transferring this heat to radiators or other heat exchangers. As the characteristic dimension of flow channels for two-phase flow becomes comparable to bubble size, the mini-channels (< 3 mm) used to direct the cooling fluid can complicate nucleate boiling heat transfer. Bubbles can encounter other heated walls, rapidly expanding and greatly reducing heat transfer as well as causing pressure oscillations and flow instabilities. The use of eletrohydrodynamic (EHD) effects, through the introduction of non-uniform electric fields, can help mitigate this problem by altering the behavior of nucleating bubbles. A combined experimental and computational study was undertaken using HFE-7100, an engineered fluid used in heat transfer applications, to investigate the potential for enhancement of nucleate boiling using EHD effects induced by applying a non-uniform electric field. In the experimental study, a minichannel was constructed consisting of an upper and lower copper electrode and glass side walls to allow visualization. The channel height and width were 3mm and 4.76 mm respectively, representative of the minichannel regime. The upper electrode was grounded while the lower electrode was heated and biased to high voltage. Optical imaging combined with post-processing and statistical analysis was used to quantify the effect of EHD on the bubble behavior. Bubbles were found to form preferentially on nucleation sites resulting from imperfections in the heated copper surface over artificially created nucleation sites. When a high voltage is applied across the electrodes, the electric field enhancement along the rim of the nucleation site is believed to influence the force balance on the forming bubble and thereby influence the bubble departure size and frequency. EHD forces also act on the bubble surface as a result of the variation in permittivity between the liquid and vapor phases, altering its shape as has been previously reported in the literature. Test results are presented that demonstrate that the application of EHD increases the nucleation site density on the heated surface and increase the bubble departure frequency from individual sites. In addition, test results are presented to show that EHD forces alter the shape of bubbles during growth and the vertical position of the detached bubbles as they are carried along in the cross flow. To better understand the underlying phenomena affecting the bubble shape and departure frequency, a numerical simulation of the bubble growth and departure was performed using COMSOL multiphysics software customized to incorporate a user-defined body force based on the Maxwell Stress Tensor. Tracking of the bubble surface, including coalescence and breakup was incorporated using the phase field variable method in which the Navier-Stokes and heat transfer equations are solved for each phase of the fluid. Results from the simulations confirmed the sensitivity of the bubble elongation and neck formation to the nucleation site geometry, specifically the angle along the rim where field enhancement occurs. The enhanced constriction of the bubble neck resulted in early detachment of bubbles when compared to simulations in which EHD was not applied. This finding provides some insight into the higher bubble departure frequency and nucleation site density observed in the experiment. The results from the combined experimental and numerical study suggest that EHD enhancement may provide a mechanism for extending the use of nucleate heat transfer to minichannels, thereby enabling additional options for cooling in compact, embedded systems. "

The inverse scattering problem is based on the scattering theory in physics, where measured data such as radiation from an object is used to determine the unique structure of the object in question. This approach has been widely successful in fields ranging from geophysics and medical imaging, to quantum field theory. In 1996 Henrik Flyvbjerg suggested that a similar approach could be used to study a reaction far from equilibrium of the self-assembly of a nucleation dependent biopolymer and, under certain conditions, uniquely determine the kinetics of the assembly. Here we use this approach to elucidate the unique structure of human islet amyloid polypeptide, also known as amylin, in-vitro. We use a systematic phenomenological analysis of the amount of monomer in fibril, of amylin, for various initial concentrations from an unstructured monomer pool. Using the assumption that nucleation is the rate-limiting step in fibril formation, we invoke mass action to develop our model. We find that the fibrillogenesis of amylin is well described by a nucleation dependent polymerization event that is characteristic of the sigmoidal shape of the reaction profile generated by our data. Furthermore, we find a second nucleation event is needed to accurately match model predictions to the observed data for the kinetic profiles of fibril formation, and the experimental length distributions of mature fibrils from in-vitro assays. This analysis allows for the theoretical determination of each step of assembly in the nucleation process. Specifically, we find the number of steps to nucleation, the size of each oligomer formed in the nucleation process, the nucleus size, and the elongation kinetics of fibrils. The secondary nucleation process is found to be a fibril dependent surface mediated nucleation event and is similar in reaction order to the primary nucleation step. Model predictions are found to be congruent with experimental assay results of oligomer populations and monomer concentration. We demonstrate that, a persistent oligomer formation is a natural and necessary consequence of nucleated fibril formation, given certain qualitative features of the kinetic profile of fibril formation. Furthermore, the modeling assumptions about monomer and fibril mass are in agreement with experiment.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 48).
The superheat required to initiate nucleate boiling inside porous wicks is not well understood in practice. This thesis reports the design of an experimental setup for investigating the onset of vapor nucleation in sintered porous structures. Pressure sensing was evaluated as an effective means of detecting the onset of nucleation. Thermal studies were conducted with a custom finite difference script in conjunction with finite element analysis. Heat conduction through a three dimensional wick was reduced to one dimensional conduction via symmetry and design constraints. The wick was optimized to achieve a temperature drop of 30 *C at a common heat pipe operating temperature of 70 °C.
by Mitchell Joseph Kelley.
S.B.