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At least 1,009 records · Page 56Linked to original sources
PubMed1990

Binding of streptococci of the "mutans" group to type 1 collagen associated with apatitic surfaces.

The present study surveyed the ability of 21 strains of cariogenic streptococci of the "mutans" group to bind to human type 1 collagen adsorbed on hydroxyapatite (HA) surfaces. All strains of Streptococcus cricetus (serotype a) and Streptococcus rattus (serotype b) tested attached strongly to collagen-treated HA (C-HA). Streptococcus mutans strains of serotype c and Streptococcus sobrinus strains of serotype d or g attached poorly; or not at all, to C-HA. S. mutans strains OMZ-175 (serotype f) and B14 (serotype e) were exceptions which exhibited significant binding to C-HA. Binding of S. cricetus AHT and S. rattus LB-1 to C-HA occurred in a dose-dependent manner, and was specific since it was inhibited by the presence of soluble collagen, but not by egg albumin, or by human fibrinogen or fibronectin. Binding occurred maximally between pH 6 and 8 and was not affected by any of several sugars tested. Trypsin treatment the streptococci had little affect, but heating at 100 degrees C reduced their ability to bind to C-HA.

Bacterial Adhesion↗
PubMed1994

The effect of prebrushing mouthrinse solutions on the desorption of albumin from apatite.

This study evaluated the desorption of radiolabelled albumin from synthetic hydroxypatite by 4 commercial prebrushing solutions: Lysoplac (containing chlorhexidine), Plax (sodium benzoate), Acti-Brush (triclosan), and Sanogyl (sodium fluoride). In 3 min, Lysoplac and Plax were found to desorb about 90% of albumin while Acti-Brush and Sanogyl failed to desorb hardly any albumin in 15 min. The desorbing effectiveness of the test solutions was not due to their pH, because when buffer solution was being tested in different ionic strengths at pH range 6-8, it appeared to desorb less than 3% of adsorbed albumin, irrespective of the pH used. The results obtained cannot, however, be directly applied to the clinical situation where much more complex interactions occur than what were tested under the present in vitro conditions.

Adsorption↗
PubMed1988

Human salivary acidic proline-rich proteins and statherin promote the attachment of Actinomyces viscosus LY7 to apatitic surfaces.

Actinomyces viscosus LY7 cells adsorbed in high numbers to experimental pellicles formed on hydroxyapatite (HA) from human parotid or submandibular saliva but not to pellicles prepared from human plasma or serum. To determine the nature of the salivary components responsible for promoting adhesion, pellicles were prepared from fractions of submandibular and parotid saliva obtained by chromatography on Trisacryl GF 2000 columns. Adsorption of LY7 cells was promoted by two groups of fractions. Each group was rechromatographed on DEAE-agarose. Fractions which promoted adsorption of LY7 cells were found by polyacrylamide gel electrophoresis to contain the acidic proline-rich proteins (PRPs) and statherin. Pellicles prepared from 12-micrograms/ml solutions of pure PRP-1, PRP-2, or parotid isoelectric focusing (PIF-slow) variant promoted maximal adsorption of A. viscosus LY7 cells. Somewhat higher concentrations of PRP-3 and PRP-4 were required for maximal adsorption, indicating that the 44-residue carboxy-terminal segment of PRP-1, PRP-2, and PIF-slow enhances LY7 binding but is not essential. Much higher concentrations of statherin were required to promote LY7 adsorption. Adsorption of LY7 cells to pellicles prepared from PRP-1 was not affected over the range of pH 5 to 8. Adsorption was also not inhibited by 50 mM lactose, which is consistent with the notion that type 1 fimbriae, rather than type 2 fimbriae, were responsible. A. viscosus T14, Actinomyces odontolyticus ATCC 17982, and Actinomyces israelii 12597 also adsorbed to PRP-1 pellicles, whereas Actinomyces naeslundii ATCC 12104 did not. Although A. viscosus cells bind strongly to adsorbed PRP-1, the presence of PRP-1 or PRP-3 in solution did not inhibit adhesion. Similarly, [3H]PRP-1 did not bind to LY7 cells, nor was it degraded when incubated with the organism. However, LY7 cells adsorbed to [3H]PRP-1 pellicles. These data suggest that hidden molecular segments of PRP become exposed when the protein adsorbs to HA; these segments then react with adhesins of LY7 cells. The apparent ability of A. viscosus cells to recognize segments of PRPs which are exposed only in surface-adsorbed molecules provides a novel mechanism which enables the organism to attach to teeth when suspended in salivary secretions.

Actinomyces↗
PubMed1991

Delineation of a segment of adsorbed salivary acidic proline-rich proteins which promotes adhesion of Streptococcus gordonii to apatitic surfaces.

Cells of several strains of Streptococcus gordonii attached in much higher numbers to experimental pellicles formed from samples of submandibular or parotid saliva on hydroxyapatite (HA) beads than to buffer controls. The nature of the salivary components responsible were investigated by preparing experimental pellicles from chromatographic fractions of submandibular saliva obtained from Trisacryl GF 2000M columns. Adhesion of S. gordonii Blackburn was promoted by two groups of fractions. The adhesion-promoting activity in the first group of fractions was associated with the family of acidic proline-rich proteins (PRPs), while that of the second group is as yet unidentified. Experimental pellicles prepared by treating HA with 2 micrograms of pure 150-amino-acid-residue PRPs (PRP-1, PRP-2, and PIF-s) promoted adhesion of S. gordonii Blackburn cells to an extent comparable to that obtained with unfractionated saliva. However, pellicles prepared from a 106-residue PRP (PRP-3) were significantly less effective, and those prepared from the amino-terminal tryptic peptide (residues 1 to 30) of the PRP and the salivary phosphoprotein statherin were completely ineffective in promoting adhesion. Although adhesion of several strains of S. gordonii was promoted by adsorbed PRP-1, the adhesion of several strains of Streptococcus sanguis or Streptococcus oralis was either not affected or only weakly enhanced by this protein. S. gordonii cells bound avidly to PRPs adsorbed onto HA beads, but the streptococci did not appear to bind PRPs in solution, since concentrations of PRP as high as 200 micrograms/ml did not inhibit binding of bacterial cells to pellicles prepared from pure PRP. S. gordonii cells also attached well to PRP or a synthetic decapeptide representing residues 142 to 150 of the PRP when the peptide was linked to agarose beads. Studies with a series of synthetic decapeptides indicated that the minimal segment of PRP which promoted high levels of S. gordonii adhesion was the carboxy-terminal dipeptide Pro-Gln (residues 149 and 150).

Adsorption↗
PubMed1984

Transmission electron microscopic identification of silicon-containing particles in synovial fluid: potential confusion with calcium pyrophosphate dihydrate and apatite crystals.

Silicon-containing particles were identified by transmission electron microscopy (TEM) in thin sections of two synovial fluids, which also contained calcium pyrophosphate dihydrate (CPPD) crystals, aspirated during acute attacks of pseudogout. Such particles, which are interpreted as probably being artefacts from glassware, were electron dense and similar in appearance to some CPPD or hydroxyapatite crystals.

Aged↗
PubMed1988

Intra-articular apatite deposition in mixed connective tissue disease: crystallographic and technetium scanning characteristics.

An acute arthritis in a patient with mixed connective tissue disease (MCTD) was found to be associated with intra-articular deposition of carbonated hydroxyapatite crystals. A technetium hydroxymethylene diphosphonate bone scan showed intense uptake in the delayed phase scan of the affected joints. Synovial fluid analysis demonstrated uptake of the radiopharmaceutical drug directly onto the crystals.

Adult↗
PubMed1979

Ultrastructural studies of synthetic apatite crystals.

In this paper a survey is given of some ultrastructural properties of synthetic hydroxyapatite. The preparation method by which single crystals with a length in the range of 0.1-3.0mm and a defined purity and stoïchiometry can be produced is given. Two groups of materials are considered in detail: carbonate-rich (greater than 0.1% CO3) and low-carbonate hydroxyapatites. The experiments on carbonate-rich material, being the most interesting from a biological point of view, show that acids attack at an active site in the hexagonal basal-plane of the crystals. Later on the crystals dissolve in the center of the crystal parallel to the c-axis forming tube-like structures. The active site can be protected from dissolution if the crystals are pretreated by EHDP or MFP. A comparison with lattice defect theory shows that most likely dislocations of the "hollow-core" type are responsible for the preferential dissolution.

Acids↗
PubMed1989

Adsorbed salivary acidic proline-rich proteins contribute to the adhesion of Streptococcus mutans JBP to apatitic surfaces.

Experimental pellicles formed on hydroxyapatite (HA) beads from parotid or submandibular saliva promoted the adhesion of Streptococcus mutans JBP cells to a greater extent than did pellicles prepared from buffer, human plasma, or serum. The nature of the salivary components responsible was studied by the preparation of pellicles from fractions of parotid saliva obtained by chromatography on Trisacryl GF 2000 columns. Two groups of fractions promoted attachment of the organism. Components migrating in the high-molecular-weight mucin fraction were most effective, but a later-eluting fraction also possessed adhesion-promoting activity. Subfractionation of the latter material indicated that the adhesion-promoting activity was associated with the acidic proline-rich proteins (PRPs). Pellicles prepared from 10-20-micrograms/mL solutions of pure PRP-1 were effective in promoting attachment of S. mutans JBP cells. PRP-3 was less effective, while human salivary statherin, fibrinogen, fibronectin, type 1 collagen, and the amino-terminal tryptic peptide derived from PRP-1 were ineffective. The quantities of 150-residue and 106-residue PRPs and of statherin, which became incorporated into experimental pellicles prepared from saliva, were estimated with use of radiolabeled protein tracers. The data obtained suggest that these proteins compete for similar binding sites on HA, and that their ratios in saliva would therefore influence the quantity of the larger PRPs that become incorporated into the pellicle. Such competition may contribute to the variability observed in the adhesion-promoting activities of different saliva samples.

Adsorption↗