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C I Hoover

Publications and source records attributed to C I Hoover.

At least 19 recordsLinked to original sources
PubMed1992

Correlation of haemagglutination activity with trypsin-like protease activity of Porphyromonas gingivalis.

Porphyromonas gingivalis is a Gram-negative anaerobic bacterium associated with various forms of periodontal disease. Several characteristics of P. gingivalis are thought to contribute to its pathogenicity; these include haemagglutination and trypsin-like protease activity. Previous studies suggest an association between haemagglutination and trypsin-like protease activity of P. gingivalis. To investigate this, two complementary quantitative experimental approaches were taken. Five independent mutants of P. gingivalis deficient in trypsin-like protease activity were shown to exhibit reduced haemagglutination activity. In addition, enhancers (cysteine and dithiothreitol) and inhibitors (N-ethylmaleimide, N-p-tosyl-L-lysine-chloromethyl ketone, and phenylmethylsulphonyl fluoride) of trypsin-like protease activity were shown, respectively, to significantly enhance and inhibit haemagglutination activity of washed, wild-type P. gingivalis cells (p less than 0.05, paired t-test). Statistical analysis indicated a strong correlation between haemagglutination and trypsin-like protease activity (r = 0.85, p less than 0.001, Spearman rank correlation). The effect of the protease enhancers and inhibitors on haemagglutination activity was specific for P. gingivalis, as they did not significantly change the haemagglutination activity of Fusobacterium nucleatum. These results suggest that the proteolytic site of the trypsin-like protease participates in haemagglutination activity of P. gingivalis.

Animals↗
PubMed1992

Transposition of Tn4351 in Porphyromonas gingivalis.

Genetic analysis of Porphyromonas gingivalis, an obligately anaerobic gram-negative bacterium, has been hindered by the apparent lack of naturally occurring bacteriophages, transposable elements, and plasmids. Plasmid R751::*omega 4 has previously been used as a suicide vector to demonstrate transposition of Tn4351 in B. uniformis. The erythromycin resistance gene on Tn4351 functions in Bacteroides and Porphyromonas. Erythromycin-resistant transconjugants were obtained at a mean frequency of 1.6 x 10(-7) from matings between Escherichia coli HB101 containing R751::*omega 4 and P. gingivalis 33277. Southern blot hybridization analysis indicated that about half of the erythromycin-resistant P. gingivalis transconjugants contained simple insertions of Tn4351 and half contained both Tn4351 and R751 sequences. The presence of R751 sequences in some P. gingivalis transconjugants most likely occurred from Tn4351-mediated cointegration of R751, since we were unable to detect autonomous plasmid in these P. gingivalis transconjugants. The P. gingivalis-Tn4351 DNA junction fragments from different transconjugants varied in size. These results are consistent with transposition of Tn4351 and with insertion at several different locations in the P. gingivalis chromosome. Tn4351 may be useful as a mutagen to isolate well-defined mutants of P. gingivalis.

Bacterial Proteins↗
PubMed1992

Adherence of oral streptococci to salivary glycoproteins.

We used an overlay method to study the ability of human salivary glycoproteins to serve as receptors for several strains of streptococci that colonize the oral cavity. Parotid and submandibular-sublingual salivas were collected as ductal secretions, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and transferred to nitrocellulose membranes. The resulting blots were overlaid with [35S]methionine-labeled bacteria, and salivary components to which the bacteria bound were detected by autoradiography. Potential glycoprotein receptors were identified for 8 of the 16 strains tested. In three cases (Streptococcus sanguis 72-40 and 804 and Streptococcus sobrinus OMZ176), highly specific interactions with a single salivary component were detected. Removal of sialic acid residues from the low-molecular-weight salivary mucin prevented adherence of one of these strains (S. sanguis 72-40), suggesting that this saccharide either mediates binding or is a critical component of the receptor site. In the remaining five strains (Streptococcus gordonii G9B and 10558, S. sanguis 10556, and Streptococcus oralis 10557 and 72-41), interactions with multiple salivary components, including the low-molecular-weight salivary mucin, highly glycosylated proline-rich glycoproteins, and alpha-amylase, were detected. These results suggest that some oral streptococci can bind specifically to certain of the salivary glycoproteins. The interactions identified may play an important role in governing bacterial adherence and clearance within the oral cavity.

Bacterial Adhesion↗
PubMed1991

Identification of genomic clonal types of Actinobacillus actinomycetemcomitans by restriction endonuclease analysis.

To evaluate its utility in discriminating different strains, restriction endonuclease analysis was applied to 12 strains of Actinobacillus actinomycetemcomitans (3 serotype a, 5 serotype b, and 4 serotype c strains). DNA isolated from each strain was digested by 12 different restriction endonucleases, and the electrophoretic banding patterns of the resulting DNA fragments were compared. The DNA fragment patterns produced by SalI, XhoI, and XbaI for the 12 A. actinomycetemcomitans strains were simple (less than 30 bands) and allowed us to recognize easily 10 distinct genomic clonal types. The three serotype a strains exhibited distinctly different clonal types from one another, the five serotype b strains exhibited an additional four distinct clonal types, and the four serotype c strains showed another three different clonal types. The other endonucleases tested were less useful in typing A. actinomycetemcomitans. We conclude that restriction endonuclease analysis is a powerful tool for typing and discerning genetic heterogeneity and homogeneity among A. actinomycetemcomitans strains. It should, therefore, be very useful for epidemiologic studies.

Aggregatibacter actinomycetemcomitans↗
PubMed1991

Association of proteases of Porphyromonas (Bacteroides) gingivalis with its adhesion to Actinomyces viscosus.

P. gingivalis adheres to A. viscosus on mineral surfaces mimicking teeth. To study whether P. gingivalis proteases contribute to its binding, mutants of P. gingivalis deficient in proteases were compared with their parent strain and a P. gingivalis-type strain for their adherence to A. viscosus on saliva-coated hydroxyapatite by manipulating a radio-isotope binding assay. Adherence of P. gingivalis 2561 to A. viscosus was studied by tests of the effects of incubation temperature and known inhibitors or promoters of proteases. Controls were handled by the assay run in PBS buffer at 22 degrees C. Two mutants deficient in trypsin-like protease were found to be deficient in adherence (% attachment relative to control: 3.2 +/- 0.1% and 11.2 +/- 0.4%), while a collagenase-deficient mutant had an adherence score (51.6 +/- 8.4) closer to that of the parent strain (75.6 +/- 7.2%). Heating P. gingivalis at 70 degrees C decreased its subsequent adherence at 22 degrees C by 80%. Adherence decreased by 60% when the assay was run at 4 degrees C, but increased by 70% at 37 degrees C. Reducing agents (dithiothreitol, cysteine, and mercaptoethanol) enhanced P. gingivalis adherence by 50 to 60%. Protease inhibitors (BZMD, SBTI, TPCK, TLCK, CMPS, PMSF) decreased adherence by 10 to 50%. Also, Hg2+ and Zn2+ decreased adherence by 30 to 50%, and arginine decreased it by 50%. Most of these effects on P. gingivalis adherence were statistically significant (p less than 0.05). Analysis of these data suggests that P. gingivalis proteases may contribute to the cohesion of P. gingivalis and A. viscosus.

Actinomyces↗
PubMed1988

Electrophoretic heterogeneity of lipopolysaccharides of Actinobacillus actinomycetemcomitans.

Electrophoretic banding patterns of lipopolysaccharides (LPS), as observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), have proved to be useful in studies relating LPS structure to virulence and as epidemiological markers. In this report, LPS of actinobacillus actinomycetemcomitans from outer membrane fractions and hot phenol-water extracts were analyzed by SDS-PAGE and LPS-specific silver-staining techniques. Both intra- and inter-strain heterogeneity of A. actinomycetemcomitans LPS was observed. Twelve strains of A. actinomycetemcomitans, representative of the three described serotypes, were assigned to LPS subtypes based on the relative mobility of their most rapidly migrating LPS band. All three serotype a strains (29523, aB75, and GA3), two (29524 and SAC11A) of five serotype b strains, and two (aB67 and SAC5A) of four serotype c strains were assigned to LPS subtype I. The three remaining serotype b strains (29522, Y4, and JP2) were assigned to LPS subtype II, and the remaining two serotype c strains (SAC6A and SAC12A) were assigned to LPS subtype III. LPS subtyping may serve as an adjunct or alternative to serotyping in epidemiological studies.

Actinobacillus↗
PubMed1988

An in vitro model to study bacterial invasion of periodontal tissues.

In periodontal disease, the abilities of bacteria to adhere to and degrade in vivo basement membranes should be considered as two of the rate-limiting steps for the potential active or passive invasion of gingival connective tissues. To study these mechanisms in greater detail, we used the PF HR-9 basement-membrane-like matrix to establish an in vitro model of bacterial invasion and degradation. Three gram-negative anaerobic periodontopathic organisms, Bacteroides gingivalis, Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans, bound in considerably higher numbers to the HR-9 matrix than did 6 strains of gram-positive facultative organisms typically associated with periodontal health. In a further experiment with B. gingivalis, the organism rapidly degraded Type IV collagen, the major macromolecular component constituting the HR-9 matrix. Streptococcus mitis, the nonperiodontopathic bacterium tested, did not degrade this model matrix. This study provides evidence that B. gingivalis, a periodontopathic bacterium, is able to adhere to and degrade basement membranes, whereas nonperiodontopathic organisms appear not to share in these abilities.

Actinobacillus↗
PubMed1987

Attachment of oral bacteria to a basement-membrane-like matrix and to purified matrix proteins.

The purpose of this study was to investigate the adherence of oral bacteria to an in vitro basement-membrane-like matrix and to selected individual macromolecular constituents of this matrix. Radiolabeled bacteria were incubated with basement-membrane-like matrices isolated from PF HR-9 cells. Bacteroides gingivalis 33277, Fusobacterium nucleatum FN-2, and Actinobacillus actinomycetemcomitans GA3(A) bound to the matrix in the range of 44 to 70%, considerably higher than the ranges of A. actinomycetemcomitans GA3(NA) and SUNY AB67 (range, 20 to 25%). The attachment of selected strains of gram-positive bacteria such as Streptococcus and Actinomyces spp. was much less frequent (range, 6 to 25%). Competitive inhibition studies demonstrated that preincubating the bacteria with fibronectin significantly decreased the binding of B. gingivalis by 51% but increased the binding of other gram-negative and gram-positive organisms tested. Similarly, preincubating the matrices with antifibronectin antibodies decreased the binding of B. gingivalis by 31%, whereas the other bacteria tested were either unaffected or binding was increased. The adherence of bacteria to purified basement membrane proteins was also investigated. Strain and species differences were seen in binding, but no clear relationship emerged between binding to an intact matrix and binding to isolated matrix proteins. The results of this study suggest that some gram-negative oral bacteria commonly associated with periodontal disease, such as B. gingivalis, A. actinomycetemcomitans, and F. nucleatum, bound in high numbers to basement-membrane-like matrices in vitro. On the other hand, the gram-positive strains tested bound in much fewer numbers. The results suggest that further studies with this in vitro model may aid in understanding the mechanisms by which oral bacteria adhere to basement membranes.

Actinobacillus↗
PubMed1986

Clinical and microbiologic effects of single-dose metronidazole or scaling and root planing in treatment of adult periodontitis.

Sites affected with adult periodontitis were observed for 3 months to compare their clinical and microbiologic responses to a single 2 g dose of metronidazole, scaling and root planing, or no treatment. 2 sites with probing depths greater than or equal to 5 mm in each of 18 female subjects (6 in each treatment group) were evaluated clinically (plaque and bleeding indices, probing depth, attachment loss) and microbiologically (%s of cocci, motile rods, non-motile rods and spirochetes, and of obligate anaerobic colony-forming units, black-pigmented Bacteroides, Fusobacterium and Actinobacillus actinomycetemcomitans in subgingival plaque). No significant differences in these variables existed between the 3 groups at baseline. The no-treatment (control) group showed no substantial clinical or microbiologic changes during the study. After 1 month, scaling and root planing had effected significant clinical improvement and significant shifts in the subgingival flora to a pattern more consistent with periodontal health; these changes were still evident at 3 months. In contrast, 1 month after metronidazole, there was some clinical improvement and a significant increase in cocci and a decrease in motile rods, but at 3 months these changes were no longer evident. The results show that the benefits of scaling and root planing are sustained for at least 3 months. However, the benefits of a single 2 g dose of metronidazole are both few and transient, indicating that this regimen, while effective against anaerobic infections in other organ systems, is not clinically or microbiologically effective in the treatment of adult periodontitis.

Adult↗
PubMed1986

Humoral responses and cross-reactivity to viridans streptococci in recurrent aphthous ulceration.

It has been proposed that recurrent aphthous ulceration (RAU) is caused by hypersensitivity to oral streptococci. This hypothesis is based on reports that RAU patients have increased levels of circulating IgG antibodies against oral streptococci, and that rabbit antisera prepared against oral streptococci are cross-reactive with oral mucosa. Using indirect immunofluorescence, we have investigated both of these reported phenomena. End-point titers of serum antibodies against three different strains of oral streptococci were assayed from nine RAU subjects with active ulcers and compared with those of nine control subjects. Titers ranged from 1:2 to 1:64 in both groups and do not appear to have any clinical or immunopathogenic significance. Cross-reactivity was studied using hyperimmune rabbit antisera raised against five different strains of oral streptococci. Homologous bacterial titers ranged from 1:1024 to 1:8192, but none of these anti-streptococcal sera produced heterologous titers greater than 1:32 with oral mucosa. This apparent low level of cross-reactivity with oral mucosal antigens appears to be non-specific and clinically insignificant. In previous reports, we have used both leucocyte migration and lymphocyte blast transformation to study cell-mediated immunity to viridans streptococci in RAU (Gadol et al., 1985; Greenspan et al., 1985). None of our results supports an immunopathogenic role for oral streptococci in RAU.

Adult↗
PubMed1985

Leukocyte migration inhibition in recurrent aphthous ulceration.

Leukocyte inhibitory factor (LIF) production in response to streptococcal antigens and oral mucosa was examined as a possible pathogenic mechanism in recurrent aphthous ulceration (RAU). Mononuclear cells from RAU patients and controls were stimulated with antigens prepared from two species of streptococci and from oral mucosa. Candida albicans and foreskin were tested as control antigens. There were some statistically significant differences in leukocyte migration inhibition between patients and controls with some concentrations of Streptococcus sanguis (ATCC 10556) and C. albicans, and a trend toward low migration indices with oral mucosa. However, the roughly equal numbers of patients and controls responding positively to each antigen and the large background variation suggest a lack of biological significance. LIF production did not increase consistently in the early stages and did not correlate with ulcer development in patients studied sequentially. We conclude that LIF production (at least in response to the antigens tested) plays no pathogenic role in RAU. Our data do not support the hypothesis that a specific cell-mediated sensitivity to streptococcal antigens is involved in RAU.

Adult↗
PubMed1985

Lymphocyte function in recurrent aphthous ulceration.

Lymphocyte blast transformation responses to mitogens and to streptococcal, adenovirus Type 1, and oral mucosal antigens were studied in 32 patients with recurrent aphthous ulceration (RAU) and matched control subjects. RAU patients showed significantly depressed (p less than 0.05) responses to mitogens in comparison with matched controls, but there was no significant difference between patients and controls in response to any of the antigens tested. These results indicate that neither cell-mediated hypersensitivity to streptococcal or viral antigens nor cross-reactivity between oral mucosal and streptococcal antigens are likely to play a role in the pathogenesis of RAU. Rather, the data support the hypothesis of an imbalance or defect in immune cell subpopulations.

Antigens↗
PubMed1984

Characterization of a trypsin-like protease from the bacterium Bacteroides gingivalis isolated from human dental plaque.

A trypsin-like, membrane-bound protease from Bacteroides gingivalis was solubilized by Triton X-100 and partially purified by a combination of DEAE-Sepharose and aminophenylmercuric Sepharose chromatography, by taking advantage of the thiol group on the enzyme. The purified enzyme hydrolysed the synthetic substrates benzoyl-L-arginine-p-nitroanilide (L-BAPA), benzoyl-D,L-arginine-beta-naphthylamide (BANA) and tosyl-L-arginine methyl ester, as well as bovine serum albumin and ovalbumin, but not tosyl-L-lysine methyl ester. The enzyme activity was enhanced by SH-reagents and was inhibited to different degrees by SH-inhibitors, chelators and microbial low-molecular-weight inhibitors such as leupeptin, antipain and chymostatin. These microbial inhibitors could be of practical use as ligands for affinity chromatography for further purification. The possible involvement of the protease in periodontal diseases is also discussed.

Bacteroides↗
PubMed1984

Comparison of two screening tests for Streptococcus mutans and evaluation of their suitability for mass screenings and private practice.

Two simple microbiological tests for quantitating salivary Streptococcus mutans levels were compared with each other and evaluated for suitability for mass screenings and private practice. Both tests use mitis salivarius medium with bacitracin (MSB) and are selective for S. mutans. One test estimates colonies grown on agar (MSBA) and the other estimates colonies grown in broth that adhere to glass (MSBB). Both are scored from 1 (lowest) to 5 (highest). Children (293) in grades 5 and 6 in Tallahassee, Florida (nonfluoridated) were tested for S. mutans levels. Scores of children by both tests were significantly similar (chi 2, regression and Kappa statistical analysis). Correlation coefficients (regression) between scores and DMFS increments of the previous 4 yr were 0.35 (MSBA) and 0.26 (MSBB). Both tests were very good in identifying children with low caries increments, but positive scores did not correlate well with high caries increments. Sampling and interpreting took 2 min (MSBA) and 1 min (MSBB). Cost of MSBA/child was $1.15, and MSBB/child $1.25. These tests are economical and suitable for mass screenings to identify low risk populations who do not require preventive treatment.

Bacteriological Techniques↗