Fibronectin-degrading enzymes in saliva and their relation to oral cleanliness.
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Adult↗
Biomedical subjects
I Etherden
Publications and source records attributed to I Etherden.
Alteration of fimbriation and cell hydrophobicity by sublethal concentrations of tetracycline.
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Actinomyces↗
Albumin as a blocking agent in studies of streptococcal adsorption to experimental salivary pellicles.
A procedure involving blocking with bovine albumin was useful for differentiating between streptococcal interactions with components of experimental salivary pellicles similar to those which form on teeth and potential interactions with uncoated areas of mineral.
Adsorption↗
Contribution of stereochemical interactions in the adhesion of Streptococcus sanguis C5 to experimental pellicles.
Parameters for the adsorption of Streptococcus sanguis C5 to experimental salivary pellicles were determined to assess the relative contributions of stereochemical and less specific hydrophobic-electrostatic interactions in this process. S. sanguis C5 cells possess hydrophobic surfaces and also an adhesin which exhibits stereochemical binding to sialic acid-containing salivary receptors. The adsorption of S. sanguis C5 to untreated pellicles was significantly better described by a two-site adsorption model than by a one-site model (p less than 0.001). One class of binding sites had an affinity for the organism that was more than 400 times that of the second class of binding sites. However, adsorption of the organism was better described by a one-site model to asialo pellicles prepared by neuraminidase treatment which destroyed the receptors for the organism's adhesin. The affinity of the organism to sites in asialo pellicles was low, and approximated that to the low-affinity sites in untreated pellicles. These observations suggest that, in the absence of stereochemical interactions involving the organism's adhesin and specific salivary receptors, S. sanguis C5 cells only exhibit low-affinity binding to experimental pellicles. This was substantiated by studies which showed that adsorption of the organism to albumin-coated hydroxyapatite and to polystyrene beads was also better described by a one-site model, and it occurred with only low affinity.
Adhesiveness↗
Concentration-dependent multiple binding sites on saliva-treated hydroxyapatite for Streptococcus sanguis.
The influence of bacterial cell concentration on estimates of the number of binding sites and the affinity for the adsorption of a strain of Streptococcus sanguis to saliva-treated hydroxyapatite was determined, and the possible presence of multiple binding sites for this organism was tested. The range of concentrations of available bacteria varied from 4.7 x 10(6) to 5,960 x 10(6) cells per ml. The numbers of adsorbed bacteria increased over the entire range tested, but a suggestion of a break in an otherwise smooth adsorption isotherm was evident. Values for the number of binding sites and the affinity varied considerably depending upon the range of available bacterial concentrations used to estimate them; high correlation coefficients were obtained in all cases. The use of low bacterial cell concentrations yielded lower values for the number of sites and much higher values for the affinity constant than did the use of high bacterial cell concentrations. When data covering the entire range of bacterial concentrations were employed, values for the number of sites and the affinity were similar to those obtained by using only high bacterial cell concentrations. The simplest explanation for these results is that there are multiple binding sites for S. sanguis on saliva-treated hydroxyapatite surfaces. When present in low concentration, the streptococci evidently attach to more specific high-affinity sites which become saturated when higher bacterial concentrations are employed. The possibility of multiple binding sites was substantiated by comparing estimates of the adsorption parameters from a computer-simulated isotherm with those derived from the experimentally generated isotherm. A mathematical model describing bacterial adsorption to binary binding sites was further evidence for the existence of at least two classes of binding sites for S. sanguis. Far fewer streptococci adsorbed to experimental pellicles prepared from saliva depleted of bacterial aggregating activity when low numbers of streptococci were used, but the magnitude of this difference was considerably less when high streptococcal concentrations were employed. This suggests an association between salivary components which possess bacterial-aggregating activity and bacterial adsorption to high-affinity specific binding sites on saliva-treated hydroxyapatite surfaces.
Adsorption↗
Association of fimbriae with the hydrophobicity of Streptococcus sanguis FC-1 and adherence to salivary pellicles.
A nonhydrophobic mutant of Streptococcus sanguis FC-1 was isolated which has a greatly diminished capacity for attaching to experimental salivary pellicles on hydroxyapatite surfaces and for aggregating with salivary components. The mutant appears to be defective in the synthesis of fimbriae, as judged by electron microscopic observations and by its inability to exhibit twitching motility.
Adhesiveness↗
Comparative hydrophobicities of oral bacteria and their adherence to salivary pellicles.
Oral bacteria were found to differ in their surface hydrophobicities as determined by their ability to adsorb to hexadecane. Strains of Actinomyces viscosus, A. naeslundii, Streptococcus sanguis, S. mitis, and Bacteroides gingivalis proved highly hydrophobic. Strains of B. intermedius, S. salivarius, S. mutans, and B. melaninogenicus were less hydrophobic, whereas strains of Actinobacillus actinomycetemcomitans were hydrophilic. An overall correlation was noted between the adsorption of bacteria to hexadecane and their numbers which attached to experimental salivary pellicles formed on hydroxyapatite surfaces. This suggests that hydrophobic bonding plays an important role in this process. Pellicles prepared from saliva which had been extracted with chloroform-methanol to remove lipids adsorbed comparable numbers of S. sanguis and A. viscosus and increased numbers of S. mutans. Analyses of adsorption isotherms indicated that pellicles formed from lipid-depleted saliva contained increased numbers of binding sites for the S. mutans strains studied, and this likely accounts for their enhanced adsorption. Absorption of saliva with 10% octyl or phenyl Sepharose reduced the protein content of saliva by almost half, but the numbers of bacteria which attached to pellicles prepared from such absorbed saliva were similar to or higher than those which attached to control pellicles. These observations suggest that saliva does not contain unique highly hydrophobic salivary macromolecules which serve as essential pellicle receptors for the bacteria studied. The data obtained are consistent with the view that hydrophobic bonding together with interactions between complementary molecules are involved in bacterial attachment to salivary pellicles on teeth.
Adsorption↗
Association of neuraminidase-sensitive receptors and putative hydrophobic interactions with high-affinity binding sites for Streptococcus sanguis C5 in salivary pellicles.
The relationship of neuraminidase-sensitive receptors and putative hydrophobic interactions to high- and low-affinity binding sites in experimental salivary pellicles for Streptococcus sanguis C5 was investigated. NaSCN, an inhibitor of hydrophobic interactions, reduced the number of cells which adsorbed to pellicles to a greater extent than NaCl or KCl when both low and high streptococcal concentrations were used in assays. However, NaSCN was not more effective than NaCl or KCl in desorbing 3H-labeled salivary pellicle components from hydroxyapatite, and NaSCN pretreatment of either strain C5 cells or the salivary pellicles did not destroy or remove either the streptococcal adhesions or the pellicle receptors. Neuraminidase treatment of pellicles or the presence of sialic acid-containing gangliosides only inhibited S. sanguis adsorption when low streptococcal concentrations were used. At these concentrations, S. sanguis adsorbs primarily to high-affinity pellicle binding sites. Adsorption isotherms indicated that neuraminidase-sensitive interactions were mainly responsible for the high affinity of these binding sites, whereas putative hydrophobic interactions inhibitable by NaSCN were mainly associated with the numbers of binding sites available. Sugar inhibition studies suggested that the two classes of binding sites previously demonstrated in untreated salivary pellicles for S. sanguis C5 are not the result of a partial conversion of high-affinity sites to low-affinity sites due to removal of sialic acid residues.
Adsorption↗
Enzymatic modification of bacterial receptors on saliva-treated hydroxyapatite surfaces.
Certain properties of experimental pellicles formed by the adsorption of salivary components on hydroxyapatite surfaces change over time. To determine whether enzymes likely to be present in the oral environment could induce such changes, pellicles were treated with saliva which had been incubated for 18 h at 35 degrees C to promote the elaboration of microbial enzymes. This treatment markedly reduced the numbers of Streptococcus mutans MT3 and JBP and S. sanguis FC-1 and C5 cells which attached, but it had little or no effect on the attachment of S. mitis RE7, Actinomyces viscosus LY7 and CK-8, Bacteroides gingivalis 381, or B. melaninogenicus subsp. intermedius 581. Heating the incubated saliva at 60 degrees C for 30 min partially reduced its pellicle-modifying activity, whereas heating at 80 degrees C for 30 min or 100 degrees C for 15 min completely eliminated such activity. This indicated that the saliva contained heat-labile substances, presumably enzymes, which could affect the pellicle receptors involved in the attachment of S. mutans and S. sanguis. Treatment of saliva-treated hydroxyapatite with commercially obtained enzyme preparations also affected bacterial attachment. Thus, treatment with galactose oxidase reduced the numbers of the S. mutans strains which attached, whereas treatment with neuraminidase reduced the adsorption of S. sanguis FC-1 but not that of S. sanguis C5. Treatment with beta-glucosidase preparations derived from almonds significantly reduced the attachment of all of the streptococcal strains studied, but, when subjected to isoelectric fractionation, the adherence-inhibiting activity did not correlate directly with beta-glucosidase activity. Treatment of the pellicles with trypsin or eight other glycosidases did not affect streptococcal attachment. Exposure of the enzymatically modified pellicles to fresh saliva did not restore the streptococcal receptors. Collectively, the data suggest that some bacterial receptors in the pellicle coating of teeth can be modified by enzymes likely to be present in the oral environment, and these interactions may affect oral bacterial ecology.
Actinomyces↗