Isolation and characterization of hemolysin activated by reductant from Prevotella intermedia.

The hemolysin from Prevotella intermedia was partially purified from culture supernatant and then characterized. The hemolysin produced a clear beta-hemolytic zone on a blood agar plate. Hemolytic activity was 2.5-fold greater in culture supernatant compared to that cell-associated. The isolation and purification procedure involved ammonium sulfate and polyethylene glycol precipitations and ion-exchange chromatographies on DEAE-Sephacel and CM-Sepharose. The activity of this hemolysin was stimulated by reductants such as cysteine, dithiothreitol, glutathione etc., and was lost upon oxidation. Trypsin or heat treatment resulted in complete inhibition of hemolytic activity. Ca(2+), Mg(2+) and EDTA did not affect the activity. The optimal pH of this hemolysin was 7.5.

In vitro study of collagen coating of titanium implants for initial cell attachment.

The aim of this study was to examine the influence of collagen coating on titanium on the initial attachment of human gingival fibroblasts for the development of the implant with periimplant soft tissue attachment. The morphological changes of cultured human gingival fibroblasts were investigated by scanning electron microcopy (SEM). Four different surfaces, i.e. non-coated mirror-polished titanium, collagen-coated titanium, non-coated tissue-culture polystyrene, and collagen-coated polystyrene were examined. Collagen coating of titanium was effective for enhancing the initial cell attachment. It is expected that collagen coating of titanium implants will improve the attachment of the peri-implant soft tissue to titanium at early stages after the implantation. SEM observation revealed the morphological effect of collagen coating on both titanium and polystyrene surfaces. Many lamellipodia and filopodia were recognized on collagen-coated titanium or polystyrene. Collagen coating improved the activity of human gingival fibroblasts.