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Biomedical subjects

C I Hoover

Publications and source records attributed to C I Hoover.

34 records · Page 2Linked to original sources
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↗
PubMed1984

Bactericidal action of bicarbonate ion on selected periodontal pathogenic microorganisms.

Organisms representative of soil, skin and fecal flora and of supragingival and subgingival flora were tested for inhibition of growth and killing by various salts (NaHCO3, NaCl, MgSO4). The antimicrobial activities of KHCO3, NaF, sodium lauryl sulfate (SLS) and chloramine T were also compared with that of NaHCO3, and the rate at which NaHCO3 exerts its bactericidal effect was studied. Suspected periodontal pathogens were more susceptible to salts than were control non-oral bacteria. Supragingival plaque organisms showed intermediate susceptibility. Periodontal pathogens were more susceptible to NaHCO3 than to NaCl; NaHCO3 and KHCO3 showed similar activity against all strains tested. Accordingly, the antibacterial activity of NaHCO3 is not simply an osmotic effect and is due to the bicarbonate ion. NaF, SLS and chloramine T had greater antimicrobial activity than NaHCO3. Supragingival bacteria required at least 6-hour exposure to 1.0 M NaHCO3 to produce 99% lethality (decrease colony-forming units by 2 log10), whereas selected periodontal pathogens were killed more rapidly (30-120 minutes). The higher the concentration of bicarbonate, the faster the lethality. Morphologic examination by transmission electron microscopy of organisms exposed to bactericidal salt concentrations revealed marked fibrillar condensations within the cytoplasm and shrinkage of the cytoplasm from the outer membrane. For NaHCO3 to be clinically effective, a high concentration must be introduced into the periodontal pocket and maintained there long enough to kill periodontal pathogens. Furthermore, NaHCO3 must be reapplied often enough to prevent recolonization by these pathogens. An advantage of NaHCO3 over NaF, SLS and other antimicrobial agents is its safety, availability and low cost.

Anti-Infective Agents, Local↗
PubMed1984

Characterization of oral streptococci that activate the dietary glycoside rutin to a mutagen.

Oral streptococci are described that hydrolyze the dietary glycoside rutin (CAS: 153-18-4), resulting in mutagenic activity. Bacteria that hydrolyze rutin were isolated from the mouth of each of 10 healthy volunteers. The activity was inducible, and the product was mutagenic in the Salmonella mutagenicity assay. These bacteria were present in the greatest proportion on the dorsum of the tongue where they formed 1.5% of the total cultivable microflora. The appearance of the colonies, cell morphology, and biochemical characteristics were those of Streptococcus milleri. However, rutin hydrolysis did not occur with any of 30 isolates of this species from blood of patients with bacteremia, with any of 4 stock strains, or with any of 14 strains of streptococci from the other 4 major oral species. Therefore, activation of rutin to a mutagen is not a universal function of the normal oral flora, but it can be accomplished by some strains of S. milleri.

Biotransformation↗
PubMed1983

Immunochemical comparison of cell-wall antigens of various viridans streptococci, including strain 2A2+3 hot from recurrent oral aphthous ulceration in man.

Several studies suggest that patients with recurrent aphthous ulceration show cell-mediated and humoral immunity to antigens of Streptococcus sanguis, particularly strain 2A2+3 HOT which is said to be antigenically similar or identical to Strep. sanguis strain ATCC 10556. However, physiological classification as well as analysis of the immunologically dominant cell-wall antigens by immunoelectrophoresis and indirect immunofluorescence showed that the strain is actually a strain of Streptococcus mitis and is antigenically more like ATCC 10557 than ATCC 10556. The findings illustrate the antigenic heterogeneity of the Strep. sanguis and Strep. mitis taxons, and demonstrate the need for antigenic analysis of viridans streptococcal strains used in immunological studies of the aetiology of disease and in antiserum production. Commercial streptococcal group and antisera were also tested.

Antigens, Bacterial↗
PubMed1983

Inhibition by acarbose, nojirimycin and 1-deoxynojirimycin of glucosyltransferase produced by oral streptococci.

Acarbose is known to inhibit glucoamylase, maltase and sucrase. Our aim was to test whether it would also inhibit glucosyltransferase (GTF), to determine the type of inhibition and to compare the inhibitor potency of acarbose with that of nojirimycin and deoxynojirimycin, two other glucosidase inhibitors. Enzyme inhibition was measured either by chemical assay or by incorporation of radioactivity into product. Acarbose effectively inhibited the synthesis of polysaccharide by GTF from strains of Streptococcus mutans and Streptococcus sanguis, but not by fructosyltransferase from Streptococcus salivarius. Acarbose and 1-deoxynojirimycin were more potent inhibitors of GTF than maltose, nojirimycin or various amino sugars. The mechanism of action of these compounds is consistent with competitive inhibition.

1-Deoxynojirimycin↗
PubMed1980

Microflora and chemical composition of dental plaque from subjects with hereditary fructose intolerance.

We compared the microbiological and chemical composition of dental plaque from subjects with hereditary fructose intolerance who restrict their dietary sugar intake with that of control subjects who do not. The two groups showed no significant differences in chemical composition of plaque: the mean protein, carbohydrate, calcium, magnesium, and phosphate contents were similar. Dental plaque from both groups contained similar numbers of total colony-forming units per microgram of plaque protein, and Streptococcus sanguis, an indigenous nonpathogen, was isolated with equal frequency from plaque samples of both groups. However, potentially odontopathic Streptococcus mutans and Lactobacillus were isolated three to four times more frequently from plaque samples of control subjects than from plaque samples of subjects with hereditary fructose intolerance. Clearly, diet (sucrose in particular) influences the colonization and multiplication of specific cariogenic organisms in dental plaque.

Adolescent↗
PubMed1977

Survival of bacteria from human dental plaque under various transport conditions.

The effects of transport media, temperature, and anaerobiosis on the survival of bacteria from human supragingival dental plaque were studied. Individual samples were obtained by passing sterile, unwaxed dental floss through the interproximal spaces. The plaque-bearing portion of floss was immediately placed in vials containing reduced transport fluid, viability-preserving microbistatic medium, or reduced salt solution transport fluid. Plaque samples were dispersed by ultrasonic oscillation, serially diluted, and plated in duplicate on MM10-sucrose-blood agar, mitis salivarius bacitracin agar, and Rogosa tomato juice agar. Initial viable counts (time 0) were compared with viable count determinations after 48- and 72-h storage. Quantitative recovery (>30%) of various groups of oral bacteria was accomplished from both reduced transport fluid and viability-preserving microbistatic medium after 48- and 72-h storage. Storage of dental plaque in reduced salt solution proved unsatisfactory for most bacteria (less than 10% survival). Since growth of some bacteria may occur in viability-preserving microbistatic medium and the charcoal present interferes with colonly enumeration on low-dilution plates, we found reduced transport fluid to be the most suitable medium for transport and recovery of bacteria from supragingival dental plaque. Subzero storage (-196 and -40 degrees C) did not enhance the survival of bacteria from dental plaque; storage at moderate (5 and 20 degrees C) temperatures gave better recovery of viable bacteria. Survival after anaerobic or aerobic storage was comparable for total colony-forming units; however, anaerobic storage enhanced survival of Streptococcus mutans and Lactobacillus. Since these organisms are specifically associated with dental caries, anaerobic techniques are preferred for caries activity testing of plaque.

Aerobiosis↗
PubMedDate not supplied

Clinical trial of a plant-derived antibody on recolonization of mutans streptococci.

OBJECTIVE: This double-blinded, placebo-controlled clinical trial tested the safety and efficacy of a topical secretory IgA antibody manufactured in tobacco plants (plantibody) in preventing recolonization of mutans streptococci (MS) in human plaque as measured by whole stimulated saliva samples. METHODS: Following a 9-day antimicrobial treatment with chlorhexidine (CHX), 56 eligible adults (enrollment salivary MS > or = 10(4) CFU/ml; no current caries) were randomized equally to a group receiving 0, 2, 4, or 6 topical applications of plantibody followed by 6, 4, 2, or 0 applications of placebo, respectively, over a 3-week period. RESULTS: Among the 54 subjects who completed the trial, the CHX regimen eliminated salivary MS in 69%. After 6 months, there were no significant differences in MS levels by number of applications, relative to placebo (p > 0.43). No adverse effects were observed. CONCLUSION: Plantibody is safe but not effective at the frequency, concentration, and number of applications used in this study.

Adult↗