Membrane damage of bacteria by silanols treatment

Antimicrobial action of silanols, a new class of antimicrobials, was investigated by transmission electron microscopy and fluorescent dye studies. Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa and Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis were treated by silanols at concentration of less than 0.2 wt percent for one hour. Membrane damage of the bacteria by the silanol treatment was clearly observed by transmission electron microscopy. Separation of the cytoplasmic membrane from the outer membrane for E. coli and disorganized cytoplasmic membrane of the Gram-positive bacteria were observed when compared to the control. Fluorescent dyes, green-fluorescent nucleic acid stain (Syto 9) and the red-fluorescent nucleic acid stain (Propidium iodide), were used to monitor membrane damage of the bacteria by Confocal microscopy and Spectrophotometer. A reduction of the green fluorescent emission was detected for silanol treated bacteria indicating membrane damage of the bacteria and supporting the hypothesis that their viability loss may be due to their membrane damage analogus to alcohols.

Ultrastructure of the adhesion of bacteria to the epithelial cell membrane of three-day postnatal rat tongue mucosa: a transmission and high-resolution scanning electron microscopic study

Togue mucosa surface of 3-day postnatal rats was examined under transmission electron microscopy (TEM) and high-resolution scanning electron microscopy (HRSEM). For HRSEM analysis, the specimens were fixed in the same solution for 24 h, postfixed in 2 percent osmiun tetroxide, critical-point dried and coated with platinum-palladium. For TEM analysis, the specimens were fixed using modified Karnovsky solution and embedded in Spurr resin. The results revealed the presence of numerous microplicae in the membrane surface of keratinized epithelial cells to which groups of bacteria were attached. These bacteria were staphylococcus and coccus organized either in rows or at random, which were visualized in three-dimensional HRSEM images. At high magnification, the TEM images revealed the adhesion of bacteria to the cell membrane through numerous filamentous structures comprising the glycocalyx. The fine fibrillar structures rising from each bacterium and from cell membrane were clearly seen. These characteristics on bacteria structure may be used for future control or prevention of bacterial diseases and for installation of the oral native flora.

A superfície lingual de ratos de três dias de idade foi examinada em microscópia eletrônica de transmissão (MET) e em microscópia eletrônica varredura de alta resolução (MEVAR). Para o método de MEVAR, os espécimes foram fixados na mesma solução por 24 h, pós fixados em solução de tetróxido de ósmio a 2 por cento, secos em ponto crítico e cobertos com platina- paládio. Para análise em MET, os espécimes foram fixados utilizando-se solução de Karnovsky modificada e emblocadas em resina Spurr. Os resultados mostraram a presença de numerosas micropregas na membrana superficial das células epiteliais queratinizadas, nas quais estavam aderidos grupos de bactérias. Estas bactérias eram estafilococos e cocos, organizados em fileiras ou a esmo, e puderam ser observadas em imagens tri-dimensionais em MEVAR. Em maiores aumentos, as imagens em MET revelaram a adesão de bactérias nas células por meio de numerosas estruturas filamentares compondo o glicocálice. As delicadas estruturas filamentares na periferia das bactérias e das células foram nitidamente identificadas. Estas características da estrutura bacteriana podem ser utilizadas, no futuro, para controle e prevenção de doenças bacteriana, bem como para a instalação da flora oral nativa.

Ultrastructure of bacteria adhesion in cell membrane of young mouse lingual mucosa

Lingual mucosa of young mouse was examined by transmission and high resolution scanning electron microscopic images (HRSEM). The specimens were fixed with modified Karnovsky solution and embedded in Spurr resin for transmission electron micrascopy. Thin sections of 80 nm were cut and examined in the Jeol 1010 transmission electron microscope. For HRSEM method, the specimens were fixed in the same solution, postfixed in osmiun tetroxide, critical point dried and coated with palladium. The samples were examined under Hitachi S-900, SEM microscope. The results revealed groups of bacteria attached to the surface of keratinized epithelial cells. These streptococcus and coccus attached on the cell membrane were noted in the three-dimensional SEM images- At high magnification, the transmission electron microscopic images demonstrated the adhesion of bacteria to the cell membrane through numerous fimbria comprising the glycocalyx. The fine fibrillar structure rising from bacteria were clearly seen.

A mucosa lingual de camundongos jovens foi examinada através de imagens de microscopia eletrônica de transmissão e de varredura de alta resolução. Os espécimes foram fixados em solução modificada de Karnovsky e emblocadas em resina Spurr para a microscopia eletrônica de transmissão. Cortes finos de 80 nm foram feitos e examinados em um microscópio eletrônico de transmissão Jeol 1010. Para a microscopia eletrônica de varredura de alta resolução os espécimes foram imersos na mesma solução, pós fixados em tetróxido de ósmio, secos e cobertos com paládio. As amostras foram examinadas em um microscópio eletrônico de varredura Hitachi S-900. Os resultados revelaram grupos de bactéria aderidos à superfície queratinizada das células epiteliais. Estes estreptococos e cocos aderidos à membrana celular foram notados em imagens tridimensionais. Em aumentos maiores, as imagens de microscopia eletrônica de transmissão demonstraram a adesão de bactéria à membrana celular através de numerosas fimbrias compondo o glicocalice. A estrutura fibrilar emergindo da bactéria foi claramente observada.

Effects of decreased cerebral perfusion pressure on cerebral hemodynamics, brain cell membrane function and energy metabolism during the early phase of experimental Escherichia coli meningitis in the newborn piglet

In this study, we tested the hypothesis that decreased cerebral perfusion pressure (CPP) induces cerebral ischemia and worsen brain damage in neonatal bacterial meningitis. Meningitis was induced by intracisternal injection of 10(9) colony forming units of Escherichia coli in 21 newborn piglets. Although CPP decreased significantly at 8 hr after bacterial inoculation, deduced hemoglobin (HbD), measured as an index of changes in cerebral blood flow by near infrared spectroscopy, did not decrease significantly. In correlation analyses, CPP showed significant positive correlation with brain ATP and inverse correlation with brain lactate levels. CPP also correlated positively with HbD and oxidized cytochrome aa3 (Cyt aa3) by near infrared spectroscopy. However, CPP did not show significant correlation with cerebral cortical cell membrane Na+,K+-ATPase activity, nor with levels of lipid peroxidation products. In summary, decreased CPP observed in this study failed to induce cerebral ischemia and further brain injury, indicating that cerebrovascular autoregulation is intact during the early phase of experimental neonatal bacterial meningitis.

Field emission scanning electron microscopy study of the mouse lingual mucosa, with special reference to adhesion of bacteria in the epithelial cell membranes

The dorsal surface of three-day postnatal mouse tongue was examined by field emission scanning electron microscope and revealed that the fungiform papillae are round in shape and filiform papillae present small projection in development. The surface of interface of epithelium-connective tissue showed small projections of papilla corresponding to the filiform and fungiform papillae. The surfaces of epithelial cell membranes present numerous microplicae with adhesion of streptococcus. These bacteria are attached on the cell membrane in organized rows of rat random, demonstrating their three-dimensional FESEM images. At high magnification, on ther surface of each bacteria may be noted small particles.