Efeito da pigmentação extrínseca nas cerâmicas à base de dissilicato de lítio submetidas aos processos de desgaste e biodegradação nas propriedades mecânicas e aderência bacteriana / Effect of extrinsic pigmentation on lithium disilicate-based ceramics subjected to wear and biodegradation processes on mechanical properties and bacterial adherence

O objetivo deste estudo foi avaliar se há alteração no comportamento mecânico e na aderência microbiológica da cerâmica à base de dissilicato de lítio com a técnica de pigmentação extrínseca aplicada, após ser submetida a diferentes condições experimentais. Foram confeccionadas 160 amostras, divididas em grupos com e sem pigmentação (n=80). Destes, cada grupo foi subdividido em Controle, Desgate, Biodegradação e Desgaste com Biodegradação (n=20).15 amostras de cada subgrupo foram submetidas ao teste de resistência à flexão e 5 para o teste de aderência microbiológica. As amostras passaram anteriormente por testes complementares para caracterização da superfície (rugosidade, perfilometria volumétrica e microscopia eletrônica de varredura (MEV)). Os resultados foram submetidos a análise estatística descritiva (média e desvio padrão) e inferencial, mediante o teste paramétrico de análise de variância (ANOVA) dois fatores e teste de Tukey ( = 0,05). O fator pigmentação extrínseca influenciou negativamente no comportamento mecânico da cerâmica, apresentando significância estatística (p = 0,000), assim como a interação entre o tipo de condição experimental e a pigmentação (p = 0,020). Entretanto, na aderência microbiológica, foi a condição experimental que influenciou negativamente no comportamento microbiológico (p = 0,000), assim como a interação entre a condição experimental e a pigmentação (p = 0,000). Nas análises complementares, observou-se que a interação entre os fatores aumentou a rugosidade superfial (p = 0,000) e aumentou o volume perdido pelo desgatse (p = 0,040). As microscopias da superficie mostram as características de cada grupo, mostrando as diferenças entre as condições experimentais com e sem pigmentação extrínseca. E as microscopias da aderência microbiológica ilustram e confirmam os resultados obtidos no teste estatístico. Concluiu-se que a pigmentação extrínseca altera as propriedades mecânicas da cerâmica de dissilicato de lítio, reduzindo a resistência à flexão e aumentando a rugosidade superficial e o desgaste. Porém, a aderência microbiológica foi aumentada pela condição experimental. Entretanto, a interação entre os fatores contribuiu para esse aumento e para agravar a alteração nas propriedades mecânicas(AU)

The objective of this study was to evaluate the mechanical and microbiological behavior of the ceramics based on lithium disilicate with extrinsic characterization. For this, 160 discs were made, divided into two large groups, with extrinsec characterization and without, after which each was divided into four groups (n = 20): Control, Wear, Biodegradation and Biodegradation with Wear. Fifteen samples from each group were submitted to the flexural strength test and 5 submitted to the microbiological adherence test. Prior to the destructive test of flexural strength, the representative samples of each group underwent complementary tests for surface characterization. The results were submitted to descriptive statistical analysis (mean and standard deviation) and inferential, using the parametric analysis of variance (ANOVA) two way and Tukey test ( = 0,05). The extrinsec characterization factor influenced the mechanical behavior of the ceramic, presenting statistical significance (p = 0.000), as well as the interaction between the type of experimental condition and the extrinsec characterization (p = 0.020). However, in the microbiological adherence, it was the experimental condition that influenced the microbiological behavior (p = 0.000), as well as the interaction between the experimental condition and the extrinsec characterization (p = 0.000). It was concluded that the makeup influenced the mechanical behavior of the ceramic, and the experimental condition influenced the microbiological adherence. The interaction between the factors influenced both the mechanical behavior and the microbiological adherence(AU)

Lactobacillus rhamnosus could inhibit Porphyromonas gingivalis derived CXCL8 attenuation

ABSTRACT An increasing body of evidence suggests that the use of probiotic bacteria is a promising intervention approach for the treatment of inflammatory diseases with a polymicrobial etiology. P. gingivalis has been noted to have a different way of interacting with the innate immune response of the host compared to other pathogenic bacteria, which is a recognized feature that inhibits CXCL8 expression. Objective The aim of the study was to determine if P. gingivalis infection modulates the inflammatory response of gingival stromal stem cells (G-MSSCs), including the release of CXCL8, and the expression of TLRs and if immunomodulatory L. rhamnosus ATCC9595 could prevent CXCL8 inhibition in experimental inflammation. Material and Methods G-MSSCs were pretreated with L. rhamnosus ATCC9595 and then stimulated with P. gingivalis ATCC33277. CXCL8 and IL-10 levels were investigated with ELISA and the TLR-4 and 2 were determined through flow cytometer analysis. Results CXCL8 was suppressed by P. gingivalis and L. rhamnosus ATCC9595, whereas incubation with both strains did not abolish CXCL8. L. rhamnosus ATCC9595 scaled down the expression of TLR4 and induced TLR2 expression when exposed to P. gingivalis stimulation (p<0.01). Conclusions These findings provide evidence that L. rhamnosus ATCC9595 can modulate the inflammatory signals and could introduce P. gingivalis to immune systems by inducing CXCL8 secretion.

Mycobacterial laminin-binding histone-like protein mediates collagen-dependent cytoadherence

When grown in the presence of exogenous collagen I, Mycobacterium bovis BCG was shown to form clumps. Scanning electron microscopy examination of these clumps revealed the presence of collagen fibres cross-linking the bacilli. Since collagen is a major constituent of the eukaryotic extracellular matrices, we assayed BCG cytoadherence in the presence of exogenous collagen I. Collagen increased the interaction of the bacilli with A549 type II pneumocytes or U937 macrophages, suggesting that BCG is able to recruit collagen to facilitate its attachment to host cells. Using an affinity chromatography approach, we have isolated a BCG collagen-binding protein corresponding to the previously described mycobacterial laminin-binding histone-like protein (LBP/Hlp), a highly conserved protein associated with the mycobacterial cell wall. Moreover, Mycobacterium leprae LBP/Hlp, a well-characterized adhesin, was also able to bind collagen I. Finally, using recombinant fragments of M. leprae LBP/Hlp, we mapped the collagen-binding activity within the C-terminal domain of the adhesin. Since this protein was already shown to be involved in the recognition of laminin and heparan sulphate-containing proteoglycans, the present observations reinforce the adhesive activities of LBP/Hlp, which can be therefore considered as a multifaceted mycobacterial adhesin, playing an important role in both leprosy and tuberculosis pathogenesis.

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

Atypical enteropathogenic Escherichia coli (aEPEC) has emerged as a significant cause of pediatric diarrheaworldwide; however, information regarding its adherence mechanisms to the human gut mucosa is lacking. Inthis study, we investigated the prevalence of several (fimA, ecpA, csgA, elfA, and hcpA) fimbrial genes in 71aEPEC strains isolated from children with diarrhea (54 strains) and healthy individuals (17 strains) in Braziland Australia by PCR. These genes are associated with adhesion and/or biofilm formation of pathogenic andcommensal E. coli. Here, the most prevalent fimbrial genes found, in descending order, were hcpA (98.6%), ecpA(86%), fimA (76%), elfA (72%), and csgA (19.7%). Phenotypic expression of pili in aEPEC strains was assessedby several approaches. We were not able to detect the hemorrhagic coli pilus (HCP) or the E. coli lamininbindingfimbriae (ELF) in these strains by using immunofluorescence. Type 1 pili and curli were detected in59% (by yeast agglutination) and 2.8% (by Congo red binding and immunofluorescence) of the strains,respectively. The E. coli common pilus (ECP) was evidenced in 36.6% of the strains on bacteria adhering toHeLa cells by immunofluorescence, suggesting that ECP could play an important role in cell adherence forsome aEPEC strains. This study highlights the complex nature of the adherence mechanisms of aEPEC strainsinvolving the coordinated function of fimbrial (e.g., ECP) and nonfimbrial (e.g., intimin) adhesins andindicates that these strains bear several pilus operons that could potentially be expressed in different nichesfavoring colonization and survival in and outside the host.

Alteraciones inmunológicas en endocarditis infecciosa / Immunological alterations in infectious endocarditis

La EI es una patología compleja, en cuya patogenia convergen factores de diversa naturaleza: infecciosos, hemodinámicos, inmunológicos, entre otros. La infección crónica constituye un estímulo antigénico persistente que induce una respuesta inmune que resulta ineficiente frente al agresor, llevando a la aparición de múltiples alteraciones inmunológicas, entre ellas alteraciones autoinmunes. Estas pueden tener o no una traducción clínica, incluso pueden simular una enfermedad autoinmune o de base inmune, por lo que el diagnóstico diferencial preciso y oportuno es fundamental. Si bien condiciones coexistentes, asociadas a inmunodeficiencia, pueden favorecer la aparición de la EI, o incidir en una mayor mortalidad, no se ha encontrado un defecto inmunológico específico en esta patología.

Endocarditis infecciosa en pediatría: un viejo problema, un reto actual / Infective endocarditis in pediatrics: An old problem, an actual challenge

La endocarditis infecciosa (EI) en pediatría es un problema de salud, lo cual se debe en gran parte a la mayor sobrevida de pacientes críticamente enfermos, a la vez que se asocia con diversos factores de riesgo. Su incidencia es variable (2-30 por ciento) y alcanza un índice de mortalidad de 72 por ciento. Los agentes etiológicos más frecuentes son los cocos gram-positivos (80-90 por ciento), y con menor índice de bacilo gram-negativos, anaerobios y hongos. Las células endocárdicas lesionadas preceden a la vegetación trombótica, con la subsecuente formación de la vegetación séptica. Clínicamente el cuadro es inespecífico y de evolución variable; sin embargo, la presencia de fiebre prolongada debe ser considerada como signo de sospecha. El apoyo diagnóstico incluye ecocardiografía, microbiología y laboratorio. El tratamiento antimicrobiano depende del agente etiológico aislado y, en circunstancias específicas, la vegectomía está indicada

Intervención del flagelo de campylobacter jejuni subsp. jejuni en la adherencia a cultivos celulares: evidencias bacteriológicas e inmunológicas / Intervention of campylobacter campylobacter jejuni subsp. jejuni flagella in the adhesion to cellular cultures: bacteriological and immunological evidences

The participation of the flagella of a virulent strain (O52) of campylobacter jejuni subsp. jejuni in the adhesion to HEp-2 cells and their inhibition by means of homologous polyclonal antibodies, moniclonal antiflagella antibodies and colostral natural antibodies (IgA) was studied. An aflagellated strain (T1) was used as negative control. Adhesion was observed in higher rates with O52 strain (72 percent) than with T1 strain (27,5 percent). Polyclonal, monoclonal and colostral antibodies inhibited O52 strain adhesion in more than 70 percent (p<0,001). T1 strain adhesion was inhibited only by polyclonal and colostral natural antibodies. Our results suggest that the flagella of C. jejuni subsp. jejuni could participate effectively in the adhesion process. However, the inhibition of T1 strain by polyclonal and colostral antibodies suggest the existence of other kinds of adhesins in the bacterial surface

Dynamics of growth and synthesis of capsular polysaccharides of actinobacillus pleuropneumoniae

Estudou-se a dinâmica de crescimento e síntese de polissacarídios capsulares de uma amostra de Actinobacillus pleuropneumoniae sorotipo 5 em diferentes condiçöes de cultivo. A bactéria foi multiplicada em caldo infuso de cérebro e coraçäo (BHI) e caldo de soja e tripticaseina (TSB), suplementados com extrato de levedura. Realizaram-se cultivos em frascos Erlenmeyer estáticos em atmosfera de CO2 e agitados em aerobiose, e em fermentador com e sem aeraçäo. Determinou-se a curva de crescimento, concentraçäo de hexosaminas, aderência a n-Hexadecano e a demanda de oxigênio em diferentes períodos de incubaçäo. A fase logarítmica de crescimento terminou mais rapidamente, e a produçäo de biomassa e de hexosaminas foram maiores nos cultivos realizados em condiçöes de aerobiose. A maior demanda de oxigênio coincidiu com o término da fase exponencial de crescimento. A aderência ao n-Hexadecano näo teve relaçäo com a fase de cultivo nem com a concentraçäo de polissacarídios capsulares

Desarrollo de un ensayo de dot-blot para la detección de adhesinas en Escherichia coli enterotoxigéna / Dot-blot immunoenzymatic reaction to detec adhesins from enteropathogenic Escherichia coli

Un método de detección de adhesinas K99, K88 y F41 de Escherichia coli enterotoxigénica ha sido desarrollado sobre membranas de nitrocelulosa, basado en la reacción inmunoenzimática de dot-blot. Suspensiones estandarizadas de este microorganismo, portando distintos tipos de adhesinas fueron sembrados en el papel y enfrentados a anticuerpos-sonda de especificidad probada y posteriormente a un conjugado peoxidasa-antianticuerpo. La prueba mostró ser de alta sensibilidad y específica del tipo de adhesina, pudiendo emplearse como ensayo diagnóstico en la detección de esos factores de virulencia

Phagocytosis of enteropathogenic Escherichia coli and Candida albicans by lectin-like receptors

1. Ingestion of enteropathogenic Escherichia coli or Candida albicans by thioglycollate-elicited macrophages and polymorphonuclear leukocytes was investigated in vitro, 2. Goat antiserum against mannose receptors caused about 50% inhibition of E. coli phagocytosis and about 90% inhibition of C. albicans phagocytosis. 3. E. coli and C. albicans uptake was inhibited by about 60% and 98%, respectively, by plating the macrophages onto substrates coated with poly-L-lysine-mannan. Further addition of 50 mM mannose to the medium significantly increased the inhibition of phagocytosis of E. coli by macrophages from 60.7 +/- 1.5 to 79.8 +/- 13.1 and by polymorphonuclear cells from 58.9 +/- 3.7 to 88.7 +/- 4.9. 4. Preincubation of phagocytic cells with antiserum against substance A of human erythrocytes reduced E. coli ingestion by 95%, but this inhibition was not observed when the antiserum was incubated with N-acetylgalactosamine (50 mM) before being added to the phagocytes. The phagocytosis of C. albicans was not inhibited by anti-substance A antiserum. 5. The phagocytosis of E. coli was inhibited by about 25% by the addition of 7.8 micrograms/ml soluble mannan to the medium, and by about 50% by the addition of 50 mMN-acetylgalactosamine; when both substances were added to the medium, an additive inhibition of about 75% was observed. 6. These results indicate that mannose receptors on the surface of phagocytic cells mediate E. coli or Candida albicans uptake and that the binding of bacteria to N-acetylgalactosamine residues from the membrane of phagocytes is also involved in the phagocytosis of E. coli