Properties of the human salivary aggregating factor for Leptotrichia buccalis cells

An in vitro investigation of the role of high molecular weight human salivary sulphated glycoprotein in periodontal wound healing

High molecular weight human salivary sulphated glycoprotein (SGP) inhibits attachment of fibroblasts to cementum in vitro and thus may enhance periodontal wound healing by repair with long junctional epithelium. However, competitive inhibition by serum constituents might prevent adequate binding of SGP for this effect to occur in vivo. The primary aim of this study was to investigate the co-adsorption in vitro, of SGP, fibronectin (FN), and albumin (ALB) to synthetic hydroxyapatite (HA) from solutions of SGP/FN (62.5/2 micrograms/mL respectively), or SGP/FN/ALB (62.5/2/4 micrograms/mL), or from individual solutions of the agents as controls: Desorption of SGP and FN was studied by preabsorbing HA with SGP or FN and subsequently exposing it to the other agent, or to buffer only as control. Adsorbates were assayed after incubation periods of up to 26 hours using specific ELISAs. SGP displaced previously adsorbed FN after 3 hours and significantly inhibited adsorption of FN and ALB compared with controls. Neither FN or ALB had a significant effect on SGP adsorption. These results are consistent with the possibility that salivary adsorption to cementum during surgery might interfere with repopulation of the root by connective tissue cells and thus contribute to wound healing by repair rather than regeneration. Separate studies taken to validate the ELISA used for SGP determination showed that HA-bound SGP contained all constituents of native SGP as revealed by SDS-PAGE and that ion exchange chromatography of SGP gave 6 fractions (I through VI), of which only the most ionic (VI) was able to inhibit cell attachment in vitro.

Purification of arginine-sensitive hemagglutinin from Fusobacterium nucleatum and its role in coaggregation

Hemagglutinin of Fusobacterium nucleatum was extracted from Triton X-100-pronase P-treated cell envelopes, and was purified by affinity chromatography on L-arginine agarose. The hemagglutinin was inactivated by heating at 70 degrees C for 1 min. The activity was inhibited by L-arginine but was not affected by any sugars or by EDTA. The hemagglutinin aggregated 14 out of 17 strains of oral streptococci tested, and the bacterial aggregating activity was also inhibited by L-arginine. The results indicate the dominant role of this hemagglutinin in the adherence of this bacterium both to host cells and to other bacteria.

Leptotrichia buccalis bacteremia in neutropenic children

Two new cases of Leptotrichia buccalis bacteremia in seriously ill patients were described. The anaerobic, gram-negative microorganism L. buccalis was isolated from blood cultures of two children with severe leukopenia. Anaerobic organisms should be taken into account when a standard protective antibiotic chemotherapy is considered in the immunosuppressed host.

Purification and characterization of galactosephilic component present on the cell surfaces of Streptococcus sanguis ATCC 10557

Previous studies have indicated that a galactosephilic component present on the bacterial cell surfaces of Streptococcus sanguis ATCC 10557 may be responsible for the salivary glycoprotein-mediated binding of the cells. The purpose of this study was to investigate the purification and characterization of galactosephilic cell surface component from S. sanguis ATCC 10557. A galactosephilic component involving fibrils on the cell surfaces was isolated by the techniques of freezing and thawing, and purified by an affinity chromatography on beta-D-galactose binding-Bio-Gel P-2 followed by gel filtrations on Bio-Gel P-150 and on Bio-Gel P-30. Both disk gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the purified product was homogeneous. The isoelectric point of the purified sample was 8.5 to 9.0. Treatment of the purified sample with pronase E reduced remarkably either the hemagglutinating activity or the precipitation reaction with proline-rich glycoprotein in human parotid saliva, suggesting that the active site may be present on the peptide moieties. When sugar specificity was examined by hemagglutination-inhibition test, D-galactose was the strongest inhibitor. The results of this study suggest that the galactosephilic component may be a bacterial lectin.