30 research outputs found
The Exopolysaccharide Matrix Modulates the Interaction between 3D Architecture and Virulence of a Mixed-Species Oral Biofilm
Virulent biofilms are responsible for a range of infections, including oral diseases. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on tooth-pellicle and bacterial surfaces provide binding sites for microorganisms; eventually the accumulated EPS enmeshes microbial cells. The metabolic activity of the bacteria within this matrix leads to acidification of the milieu. We explored the mechanisms through which the Streptococcus mutans-produced EPS-matrix modulates the three-dimensional (3D) architecture and the population shifts during morphogenesis of biofilms on a saliva-coated-apatitic surface using a mixed-bacterial species system. Concomitantly, we examined whether the matrix influences the development of pH-microenvironments within intact-biofilms using a novel 3D in situ pH-mapping technique. Data reveal that the production of the EPS-matrix helps to create spatial heterogeneities by forming an intricate network of exopolysaccharide-enmeshed bacterial-islets (microcolonies) through localized cell-to-matrix interactions. This complex 3D architecture creates compartmentalized acidic and EPS-rich microenvironments throughout the biofilm, which triggers the dominance of pathogenic S. mutans within a mixed-species system. The establishment of a 3D-matrix and EPS-enmeshed microcolonies were largely mediated by the S. mutans gtfB/gtfC genes, expression of which was enhanced in the presence of Actinomyces naeslundii and Streptococcus oralis. Acidic pockets were found only in the interiors of bacterial-islets that are protected by EPS, which impedes rapid neutralization by buffer (pH 7.0). As a result, regions of low pH (<5.5) were detected at specific locations along the surface of attachment. Resistance to chlorhexidine was enhanced in cells within EPS-microcolony complexes compared to those outside such structures within the biofilm. Our results illustrate the critical interaction between matrix architecture and pH heterogeneity in the 3D environment. The formation of structured acidic-microenvironments in close proximity to the apatite-surface is an essential factor associated with virulence in cariogenic-biofilms. These observations may have relevance beyond the mouth, as matrix is inherent to all biofilms
Concentração de fluoreto em arroz, feijão e alimentos infantis industrializados
OBJETIVO: Determinar a concentração de fluoreto na refeição brasileira típica (arroz e feijão) e em alimentos infantis industrializados e estimar suas contribuições para fluorose dental. MÉTODOS: Os alimentos foram adquiridos de supermercados das cidades de Piracicaba e Campinas, SP, Brasil. Os alimentos infantis industrializados foram comprados em 2001 e o arroz e feijão em 2003, e imediatamente analisados. Foram analisadas três marcas de arroz, três de feijão e 36 amostras de alimentos infantis divididos em cinco grupos: prontos para o consumo; mingaus; alimentos formulados; leites em pó e outros alimentos. No arroz e feijão, foram determinadas as concentrações de fluoreto nas sementes "in natura" e após cozimento com água destilada ou fluoretada (0,7 ppm). Todas as análises de fluoreto foram feitas com eletrodo específico. Considerou-se 0,07 mg/kg/dia como a dose limite de exposição a fluoreto para risco de fluorose. RESULTADOS: A concentração de fluoreto encontrada nos grãos de arroz e feijão foi baixa. Porém, a concentração aumentou 100-200 vezes após cozimento em água fluoretada e mesmo assim, foi menor que a encontrada em alguns alimentos industrializados. Uma refeição com arroz e feijão preparada com água fluoretada seria responsável por 29% da dose limite de ingestão de fluoreto em termos de fluorose aceitável; a contribuição de alguns alimentos industrializados atingiria 45%. CONCLUSÕES: A alimentação típica brasileira, mesmo preparada com água fluoretada, é mais segura em termos de risco de fluorose dental que alguns alimentos infantis industrializados
Biology of Streptococcus mutans-Derived Glucosyltransferases: Role in Extracellular Matrix Formation of Cariogenic Biofilms
The importance of Streptococcus mutans in the etiology and pathogenesis of dental caries is certainly controversial, in part because excessive attention is paid to the numbers of S. mutans and acid production while the matrix within dental plaque has been neglected. S. mutans does not always dominate within plaque; many organisms are equally acidogenic and aciduric. It is also recognized that glucosyltransferases from S. mutans (Gtfs) play critical roles in the development of virulent dental plaque. Gtfs adsorb to enamel synthesizing glucans in situ, providing sites for avid colonization by microorganisms and an insoluble matrix for plaque. Gtfs also adsorb to surfaces of other oral microorganisms converting them to glucan producers. S. mutans expresses 3 genetically distinct Gtfs; each appears to play a different but overlapping role in the formation of virulent plaque. GtfC is adsorbed to enamel within pellicle whereas GtfB binds avidly to bacteria promoting tight cell clustering, and enhancing cohesion of plaque. GtfD forms a soluble, readily metabolizable polysaccharide and acts as a primer for GtfB. The behavior of soluble Gtfs does not mirror that observed with surface-adsorbed enzymes. Furthermore, the structure of polysaccharide matrix changes over time as a result of the action of mutanases and dextranases within plaque. Gtfs at distinct loci offer chemotherapeutic targets to prevent caries. Nevertheless, agents that inhibit Gtfs in solution frequently have a reduced or no effect on adsorbed enzymes. Clearly, conformational changes and reactions of Gtfs on surfaces are complex and modulate the pathogenesis of dental caries in situ, deserving further investigation
Temperature safety profile of laparoscopic devices: Harmonic ACE (ACE), Ligasure V (LV), and plasma trisector (PT)
Background Reports of iatrogenic thermal injuries during laparoscopic surgery using new generation vessel-sealing devices, as well as anecdotal reports of hand burn injuries during hand-assisted surgeries, have evoked questions about the temperature safety profile and the cooling properties of these instruments. Methods This study involved video recording of temperatures generated by different instruments (Harmonic ACE [ACE], Ligasure V [LV], and plasma trisector [PT]) applied according the manufacturers` pre-set settings (ACE setting 3; LV 3 bars, and the PT TR2 50W). The video camera used was the infrared Flex Cam Pro directed to three different types of swine tissue: (1) peritoneum (P), (2) mesenteric vessels (MV), and (3) liver (L). Activation and cooling temperature and time were measured for each instrument. Results The ACE device produced the highest temperatures (195.9 degrees +/- 14.5 degrees C) when applied against the peritoneum, and they were significantly higher than the other instruments (LV = 96.4 degrees +/- 4.1 degrees C, and PT = 87 degrees +/- 2.2 degrees C). The LV and PT consistently yielded temperatures that were < 100 degrees C independent of type of tissue or ""on""/ ""off"" mode. Conversely, the ACE reached temperatures higher than 200 degrees C, with a surprising surge after the instrument was deactivated. Moreover, temperatures were lower when the ACE was applied against thicker tissue (liver). The LV and PT cooling times were virtually equivalent, but the ACE required almost twice as long to cool. Conclusions The ACE increased the peak temperature after deactivation when applied against thick tissue (liver), and the other instruments inconsistently increased peak temperatures after they were turned off, requiring few seconds to cool down. Moreover, the ACE generated very high temperatures (234.5 degrees C) that could harm adjacent tissue or the surgeon`s hand on contact immediately after deactivation. With judicious use, burn injury from these instruments can be prevented during laparoscopic procedures. Because of the high temperatures generated by the ACE device, particular care should be taken when it is used during laparoscopy
In vitro and in vivo effects of isolated fractions of Brazilian propolis on caries development
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORRecently, two chemically different types of Brazilian propolis (type-3 and -12) were shown to have cariostatic properties. This study aimed to evaluate the influence of their isolated fractions on mutans streptococci viability, glucosyltransferases (GTFs) activity and caries development in rats. The ethanolic extracts of propolis (EEPs) were serially fractionated into hexane (H-fr), chloroform, ethyl acetate, and ethanol. The ability of the four fractions and EEP to inhibit Streptococcus mutans and Streptococcus sobrinus growth and adherence to a glass surface was examined. The effect on GTFs B and C activity was also determined. For the caries study, 60 Wistar rats infected with Streptococcus sobrinus were treated topically twice daily as follows: (1) EEP type-3, (2) H-fr type-3, (3) EEP type-12, (4) H-fr type-12, and (5) control. In general, the H-fr from both types of propolis showed the highest antibacterial activity and GTFs inhibition. Furthermore, the EEP and H-fr type-3 and -12 were equally effective in reducing dental caries in rats. The data suggest that the putative cariostatic compounds of propolis type-3 and -12 are mostly non-polar; and H-fr should be the fraction of choice for identifying further potentially novel anti-caries agents1011-3110115FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIOR1999/1205-1968474/00-52164/01-
The influence of a novel propolis on mutans streptococci biofilms and caries development in rats
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ -CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOA flavonoids-free Brazilian propolis (type 6) showed biological effects against mutans streptococci and inhibited the activity of glucosyltransferases. This study evaluated the influence of the ethanotic extract of a novel type of propolis (EEP) and its purified hexane fraction (EEH) on mutans streptococci biofilms and the development of dental caries in rats. The chemical composition of the propolis extracts were examined by gas chromatography/mass spectrometry. The effects of EEP and EEH on Streptococcus mutans UA159 and Streptococcus sobrinus 6715 biofilms were analysed by time-kilt and glycolytic pH drop assays. Their influence on protontranslocating F-ATPase activity was also tested. In the animal study, the rats were infected with S. sobrinus 6715 and fed with cariogenic diet 2000. The rats were treated topically twice a day with each of the extracts (or control) for 5 weeks. After the experimental period, the microbial composition of their dental plaque and their caries scores were determined. The results showed that fatty acids (oleic, palmitic, linoleic and stearic) were the main compounds identified in EEP and EEH. These extracts did not show major effects on the viability of mutans streptococci biofilms. However, EEP and EEH significantly reduced acid production by the biofilms and also inhibited the activity of F-ATPase (60-65%). Furthermore, both extracts significantly reduced the incidence of smooth surface caries in vivo without displaying a reduction of the percentage of S. sobriuns in the animals' plaque (P < 0.05). However, only EEH was able to reduce the incidence and severity of sulcal surface caries (P < 0.05). The data suggest that the cariostatic properties of propolis type 6 are related to its effect on acid production and acid tolerance of cariogenic streptococci; the biological activities may be attributed to its high content of fatty acids5111522FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ -CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ -CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2001/13903-1300627/92-