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Biomedical subjects

W B Clark

Publications and source records attributed to W B Clark.

At least 73 records · Page 4Linked to original sources
PubMed1988

Natural occurrence of black-pigmented Bacteroides species in the gingival crevice of the squirrel monkey.

The objective of this study was to determine whether the squirrel monkey (Saimiri scuireus) is indigenously colonized with black-pigmented bacteroides (BPB) resembling human Bacteroides gingivalis and Bacteroides intermedius (suspected periodontal pathogens) and to determine the usefulness of the squirrel monkey as an in vivo model for studying colonization by putative pathogens. We assayed the subgingival plaques of 138 monkeys of various ages and in four different colonies for the presence of anaerobic BPB microorganisms. We also tested half the animals for the presence of Actinobacillus actinomycetemcomitans. Clinical indices and levels of serum antibody to B. gingivalis were recorded. We detected BPB in 50% of the animals and A. actinomycetemcomitans in 69% of the animals. The presence of BPB was generally associated with increased age, increased gingival index, presence of calculus, and increased levels of serum antibody. These data indicate that the squirrel monkey may be a good model for studying the parameters of natural infection of the gingival crevice with suspected periodontopathogenic BPB microorganisms.

Age Factors↗
PubMed1987

Changes in American drinking patterns and problems, 1967-1984.

Data from a 1984 general population survey of drinking practices and problems in the United States are compared with those from identically worded items in a 1967 survey. Results indicate that beverage preference changed between 1967 and 1984. Americans consumed more wine and beer but fewer distilled spirits in 1984. However, the volume of drinks consumed did not change significantly. There were few significant differences in drinking patterns with the exception of a small increase in the percentage of men who were abstainers in 1984. Mixed findings were obtained with regard to drinking problems. Little difference was found over time in the proportion of respondents experiencing any of nine possible problem consequences, but there was an increase in the proportion who reported experiencing one of four possible dependence problems. Implications of this survey for the single distribution theory of consumption are discussed.

Adult↗
PubMed1986

Fimbria-specific antibodies in serum and saliva of mice immunized with Actinomyces viscosus T14V fimbriae.

Fimbria-specific antibody responses were compared in mice immunized with purified fimbrial adhesins in the region of the submandibular gland (i.e., local site) or at a remote site in the back. One hundred micrograms of fimbriae isolated from Actinomyces viscosus T14V was used as the vaccine. Four subcutaneous injections of the vaccine in the local site induced greater amounts of fimbria-specific immunoglobulin G (IgG) in serum and saliva than three injections. However, there was no difference in the response of fimbria-specific IgA in serum and saliva. Fimbria-specific IgG in serum and saliva were first detected 21 days after the primary immunization at both the local or remote sites. Fimbria-specific IgA in serum was first detected 28 days after the primary immunization at both the local or remote sites. However, fimbria-specific IgA in saliva occurred only in mice immunized with the fimbrial vaccine at the local site and was first detected 14 days after the primary immunization. Both serum and saliva from mice immunized 4 times with the fimbrial vaccine in the local site inhibited in vitro adsorption of strain T14V cells to hydroxyapatite beads pretreated with normal mouse saliva, whereas adsorption of strain T14V cells suspended in serum and saliva from sham-immunized animals was not inhibited. Collectively, these data suggest that mice immunized locally in the submandibular gland region with a vaccine composed of purified fimbrial adhesins provide a potential model for evaluating the efficacy of fimbria-specific antibodies in saliva to inhibit strain T14V colonization of tooth surfaces.

Actinomyces↗
PubMed1986

Modulation of Actinomyces viscosus colonization of mouse teeth in vivo by immunization with fimbrial adhesins.

Experiments were performed to determine whether immunization of mice with fimbrial adhesins isolated from Actinomyces viscosus T14V could modulate infection of tooth surfaces in animals challenged with the homologous strain. Saliva and sera from animals immunized in the submandibular gland region contained elevated levels of fimbria-specific immunoglobulin A (IgA) and IgG, whereas saliva and sera from sham-immunized animals did not. There was a statistically significant inverse correlation between the presence of fimbria-specific antibodies in saliva and serum and the levels of bacterial colonization on molar tooth surfaces. These results suggest that fimbrial adhesins may effectively modulate infection of tooth surfaces by periodontopathic bacteria.

Actinomyces↗
PubMed1986

Actinomyces viscosus colonization of mouse teeth.

The implantation of Actinomyces viscosus strain T14V-J1 was studied in mice in vivo. The optimum age range for implantation was from 40 to 80 days. The minimum infective dose of strain T14V-J1 required for colonization in all inoculated animals (ID100) was 5 X 10(8) CFU for 40-day-old mice and 1 X 10(9) CFU for 100-day-old mice. The high ID100 required for implantation of strain T14V-J1 in these mice is consistent with the finding that tooth surfaces of these animals are not colonized by detectable indigenous Actinomyces. The infection could also be transmitted to non-infected mice housed with infected mice. This in vivo model can be used to evaluate the potential for reducing or preventing Actinomyces colonization on teeth by vaccination with fimbrial adhesins.

Actinomyces↗
PubMed1986

Actinomyces adsorption mediated by type-1 fimbriae.

Monospecific antibody against the type-1 fimbriae of Actinomyces viscosus T14V reacted with 12 strains of A. viscosus (serotype 2), 12 strains of A. naeslundii (serotype 2 or serotype 3), but not with 11 serotype 1 strains of A. naeslundii. All strains positive for the type-1 fimbrial antigen adsorbed strongly to saliva-treated hydroxyapatite, and in many instances (18 of 24 strains) this interaction was inhibited by the monospecific antibody. These findings strongly suggest that only those strains of actinomyces which possess type-1 fimbriae adhere to the tooth surfaces, and that these fimbriae constitute the principal adhesin involved in this interaction.

Actinomyces↗
PubMed1985

Relative hydrophobicities of Actinomyces viscosus and Actinomyces naeslundii strains and their adsorption to saliva-treated hydroxyapatite.

The present study examined 42 strains of Actinomyces spp. to determine whether adsorption to saliva-treated hydroxyapatite (SHA) of the selected strains of this prominent group of dental-plaque bacteria correlated with hydrophobicity. The relative hydrophobicity of the strains was determined by their adsorption to hydrophobic gels (i.e., phenyl-Sepharose) and their aggregation in ammonium sulfate. Within serogroups the relative hydrophobicity for the strains was similar. The relative adsorption of strains to SHA was also similar within the respective serogroups. Strains which were relatively hydrophobic, as judged by their binding to the hydrophobic gel and aggregation in low concentrations of ammonium sulfate, adsorbed well to SHA. Strains which adsorbed poorly to SHA were relatively hydrophilic since they did not bind well to the hydrophobic gel and were only aggregated in relatively high concentrations of ammonium sulfate. Tween 80, a nonionic detergent known to inhibit hydrophobic interactions, blocked binding of cells to the hydrophobic gel, suggesting that hydrophobic interactions had been inhibited. However, Tween 80 exhibited no influence on the adsorption of cells to SHA. Thus, although there was a strong statistical correlation between the relative hydrophobicity of a strain and its adsorption to SHA, the data were consistent with the view that other interactions, such as ionic bonds and interactions between complimentary macromolecules, are involved in adsorption of the Actinomyces strains to SHA.

Actinomyces↗
PubMed1985

Antigenic variation of indigenous streptococci.

Isolates of Group D streptococci indigenous to the murine oral cavity were studied to detect the occurrence of antigenic variation. Group D streptococci cultured from molar homogenates of Balb/c mice were randomly selected for study on the basis of distinctive colony morphology. Isolates obtained over a 12-week period were biotyped using the API 20S system, and subjected to Lancefield extraction and rocket immunoelectrophoresis for serotyping. All isolates were compared with an arbitrarily selected standard test strain (W1S-1) isolated the first week of the first experimental series. Four biotypes were encountered during the first week of two experimental series. Two very unusual biotypes detected during the first experimental series persisted throughout that series, as did two more common biotypes throughout the second experimental series. Anti-W1S-1 serum produced three precipitin bands (antigens O, D, and K) against W1S-1 Lancefield extract and against the respective biotypes detected during the first week of the two series. Of the three antigens detected, only the group antigen (D) did not vary during either experimental series. Antigenic variants lacking the O or K antigen and bearing these distinctive phenotypes were repeatedly isolated in subsequent weeks. Ultimately, 16% of 190 strains isolated during the first series and 26% of 167 strains isolated during the second series proved to be antigenic variants of the predominant biotypes detected in both series.

Animals↗
PubMed1984

Specific inhibition of adsorption of Actinomyces viscosus T14V to saliva-treated hydroxyapatite by antibody against type 1 fimbriae.

Specific antibodies and their Fab fragments were used to study adsorption of Antinomyces viscosus T14V to saliva-treated hydroxyapatite. Antibody against A. viscosus T14V blocked adsorption of the strain to saliva-treated hydroxyapatite, and this activity was removed after preincubation of the immune immunoglobulin G (IgG) with purified type 1 fimbriae in amounts near equivalence but not after preincubation with type 2 fimbriae in antigen excess. Specific IgG or Fab fragments against type 1 fimbriae inhibited adsorption of strain T14V to saliva-treated hydroxyapatite and promoted desorption of cells already attached to the apatite surface. Anti-type 2 IgG or Fab fragments did not possess these activities. These data demonstrate that type 1 but not type 2 fimbriae mediate adsorption of strain T14V to the saliva-treated hydroxyapatite surface.

Actinomyces↗
PubMed1983

Influence of physicochemical parameters on adsorption of Actinomyces viscosus to hydroxyapatite surfaces.

Adsorption of Actinomyces viscosus strains T14V and T14AV to saliva-treated and untreated hydroxyapatite (HA) under various environmental conditions was studied. Strain T14V adsorption to saliva-treated HA was not influenced by pH, whereas strain T14AV adsorbed in higher numbers under acidic conditions. The addition of cations inhibited adsorption of strains T14V and T14AV to saliva-treated HA. Strain T14V possessed a greater affinity for hydrophobic gels than did strain T14AV, but incorporation of non-ionic detergents, which inhibit hydrophobic interactions, did not influence adsorption of strain T14V to saliva-treated HA. Adsorption of strain T14V to saliva-treated HA increased in the presence of an anionic detergent; however, strain T14AV adsorption was not affected. Strain T14V adsorption decreased in the presence of a cationic detergent, whereas strain T14AV adsorption increased. Collectively, these data suggest that electrostatic interactions, but not hydrophobic interactions, are of major importance in the adsorption of strain T14V to saliva-treated HA.

Actinomyces↗
PubMed1981

Role of surface fimbriae (fibrils) in the adsorption of Actinomyces species to saliva-treated hydroxyapatite surfaces.

We studied the adsorption, morphological, and serological characteristics of selected Actinomyces and related species. Evaluation of uranyl acetate-stained cells by electron microscopy revealed wide variations among strains in the frequency of surface fimbriae. These variations did not always correlate with the percent adsorption to saliva-treated hydroxyapatite of the various Actinomyces strains. However, two strains of Rothia dentocariosa possessing no surface fimbriae and five strains of A. israelii possessing very few surface fimbriae exhibited feeble adsorption to saliva-treated hydroxyapatite. Although the calculated number of adsorption sites on saliva-treated hydroxypatite did not vary widely among the strains tested, significant differences were observed in the affinities calculated for some species or serotypes. The mean affinities for strains of A. viscosus serotype 2 and A. naeslundii serotype 3 were similar, and these strains adsorbed well to saliva-treated hydroxyapatite. The mean adsorption and affinity for the A. naeslundii strain serotype 1 and all strains of A. israelii tested were significantly less than those determined for the A. viscosus serotype 2 or A. naeslundii serotype 3 strains. Adsorption inhibition activity of antiserum to strain T14V, previously shown to be solely related to antibodies in immune serum directed against the VA1 fimbria (fibril) antigen, was removed by preadsorption of the antiserum with most A. viscosus and A. naelundii strains, but not with A. israelii strains. This suggests some cross-reactivity among strains of A. viscosus and A. naeslundii but not A. israelii. Adsorption to saliva-treated hydroxyapatite of all A. viscosus and A. naeslundii strains tested was strongly inhibited by fimbriae isolated from A. viscosus strain T14V. Collectively, these data suggest that the adsorption of certain A. viscosus and A. naeslundii strains is mediated by surface fimbriae, many of which appear serologically cross-reactive with strain T14V fimbriae.

Actinomyces↗
PubMed1980

Prenatal determination of fetal brain and somatic weight by ultrasound.

A new method of determining fetal weight in utero is presented. Because it is based on multiple ultrasound measurements which encompass population and individual variations in fetal anthropometry, the method should be applicable to fetuses drawn from different populations. The components of fetal weight are separated into two variables, brain weight and somatic weight, which are independently determined. Their sum provides good estimates of total fetal weight in normal cases as well as those with asymmetrical growth retardation (Sy = 83 gm). The method generates the data required for interpreting fetal weight estimates in terms of any alteration in the brain:somatic weight relationship. It, therefore, yields quantitative information on the severity of asymmetrical IUGR.

Birth Weight↗
PubMed1980

Fibril-mediated adherence of Actinomyces viscosus to saliva-treated hydroxyapatite.

Fibril-mediated adherence of Actinomyces viscosus strain T14V cells to saliva-treated hydroxyapatite was studied. Fibrils were purified by ammonium sulfate precipitation and differential centrifugation from the crude supernatant of whole cells that were sheared by one passage through a French pressure cell. Purified fibrils and crude supernatant inhibited strain T14V adherence to saliva-treated hydroxyapatite to similar extents. However, anti-strain T14V serum and antifibril specific antibody completely abolished strain T14V adherence. The blocking immunoglobulin could be adsorbed from anti-T14V serum by strain T14V whole cells, by purified fibrils, and, to a lesser extent, by cell walls. It was concluded that fibrils mediate adherence of strain T14V cells to saliva-treated hydroxyapatite. In addition, fibril preparations were shown to contain more than 95% protein and to be antigenically homogeneous by immunodiffusion and Laurell rocket immunoelectrophoresis. Purified fibril preparations showed serological identity with the virulence-associated 1 antigen of Lancefield-extracted T14V cells, whereas crude supernatants contained both virulence-associated 1 and virulence-associated 2 antigens, as shown by rocket immunoelectrophoresis.

Actinomyces↗