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Biomedical subjects

R J Genco

Publications and source records attributed to R J Genco.

At least 145 records · Page 8Linked to original sources
PubMed1989

Heterogeneity of virulence among strains of Bacteroides gingivalis.

The ability of fresh isolates of B. gingivalis to establish abscesses in the mouse model was studied by comparing them with established laboratory strains of B. gingivalis. Eight fresh isolates obtained from plaque associated with periodontal disease and grown under similar conditions as established strains were injected subcutaneously on the back of the mouse. All of these strains produced secondary lesions on the abdomen. Septicemia was associated with seven of the strains. Two commonly used laboratory strains, W50 and W83, also produced secondary lesions and septicemia. Five other laboratory strains produced only localized abscesses. On histologic examination, the strains that produced disseminated disease showed invasion of connective disease by individual bacteria that were not in clumps. The strains that produced localized abscesses were characterized by growing in colonies or clumps in the abscess cavity. Four synthetic enzyme substrates were examined to determine whether the differences between invasive and non-invasive strains were due to differences in proteolytic enzyme production. No differences in enzyme production could be demonstrated with the selected substrates.

Abscess↗
PubMed1989

The specific pathogen-free human: a new frontier in oral infectious disease research.

The indigenous flora acts as a deterrent to the establishment of some pathogenic species. We propose that advances in oral health research will lead to control of oral infections by altering the indigenous microflora to create a specific pathogen-free human. Investigations of important endogenous and exogenous factors which affect the oral flora and the interactions among these parameters, in health and disease, will have to be undertaken for this goal to be achieved. Several approaches to produce a specific pathogen-free human include: (1) introduction of individual or collective moieties which inhibit detrimental interactions on a genetic and molecular level; (2) genetic modification of salivary flow and protein composition by use of transgenic techniques; (3) therapeutic replacement with altered bacterial strains; (4) alteration of host immune responses to produce specific isotype immunity at the most appropriate time in the ontogeny of the oral environment; (5) production of isotype and/or antigen-specific regulatory molecules at the most appropriate time in development; (6) use of synthetic vaccines; (7) genetic alteration or replacement of cells with defective protective capabilities; and (8) use of anti-idiotype vaccines.

Germ-Free Life↗
PubMed1988

Repair of periodontal furcation defects in beagle dogs following reconstructive surgery including root surface demineralization with tetracycline hydrochloride and topical fibronectin application.

This study examines the effects of root surface demineralization and topical fibronectin as adjuncts to reconstructive periodontal surgery. In 14 beagle dogs, horizontal periodontal defects were surgically induced around the mandibular premolars followed by a 6-week period without plaque control. Reconstructive surgery of the defects was subsequently carried out. The root surfaces were debrided and superficially demineralized with citric acid or tetracycline hydrochloride, with or without subsequent application of fibronectin. Mucoperiosteal flaps were raised to cover most of the crowns and sutured. The animals were sacrificed 12 weeks after surgery and block sections of the teeth and surrounding tissues were processed for histology. Analysis included incidence of furcation defects presenting with an epithelial lining, quantification of connective tissue repair relative to the furcation circumference, and regeneration of alveolar bone relative to the furcation defect height. The incidence of root resorption and ankylosis was also analyzed. Within the limitations of this study it was concluded that: (1) citric acid conditioning of the root surface frequently resulted in complete connective tissue repair of the furcation defect; (2) root resorption and ankylosis were prevalent features of the healing response; (3) citric acid and tetracycline treatment had similar potential to induce connective tissue repair and resulted in corresponding incidences of root resorption and ankylosis; (4) application of fibronectin to demineralized root surfaces did not enhance the amount of connective tissue repair and did not alter the pattern of root resorption and ankylosis.

Administration, Topical↗
PubMed1988

Serological studies of oral Bacteroides intermedius.

Bacteroides intermedius is a gram negative, anaerobic microorganism associated with certain forms of human periodontal disease, including adult periodontitis and acute necrotizing ulcerative gingivitis. Previous studies have indicated the presence of two DNA homology groups which could be distinguished by analysis of protein patterns on polyacrylamide gel electrophoresis, as well as at least two serogroups within B. intermedius. The present study examined the serology of B. intermedius and determined the distribution of B. intermedius serogroups in clinical isolates and patient plaque samples. Serological reactions with unabsorbed rabbit antisera and antisera immunoabsorbed with B. intermedius strains demonstrated a previously unreported antigenic group within B. intermedius, serogroup C, in both immunodiffusion and immunofluorescence assays. Of 79 B. intermedius isolates from 68 subjects examined with specific antisera, 55% of the isolates and 52% of the subjects were categorized in serogroup C, 40% of the isolates and 46% of the subjects were in serogroup B, and 5% of the isolates and 6% of the subjects were in serogroup A. In 31 samples of subgingival dental plaque from adolescents known to harbor B. intermedius, 81% demonstrated serogroup B, 16% had serogroup A, and 3% had serogroup C.

Animals↗
PubMed1988

Molecular cloning and sequencing of the gene encoding the fimbrial subunit protein of Bacteroides gingivalis.

The gene encoding the fimbrial subunit protein of Bacteroides gingivalis 381, fimbrilin, has been cloned and sequenced. The gene was present as a single copy on the bacterial chromosome, and the codon usage in the gene conformed closely to that expected for an abundant protein. The predicted size of the mature protein was 35,924 daltons, and the secretory form may have had a 10-amino-acid, hydrophilic leader sequence similar to the leader sequences of the MePhe fimbriae family. The protein sequence had no marked similarity to known fimbrial sequences, and no homologous sequences could be found in other black-pigmented Bacteroides species, suggesting that fimbrillin represents a class of fimbrial subunit protein of limited distribution.

Amino Acid Sequence↗
PubMed1988

Correlations between gingival crevicular fluid enzymes and the subgingival microflora.

Bacteroides gingivalis is a Gram-negative micro-organism implicated in the pathogenesis of adult periodontitis and producing relatively large amounts of specific enzymes. In the present study, subgingival samples taken from adults with moderate periodontitis were examined for the presence and relative amounts of enzymatic activity toward certain substrates. Enzyme levels were then correlated with clinical periodontal indices and microbiological analysis of subgingival plaque, including darkfield microscopy for bacterial morphotypes and immunofluorescence microscopy for B. gingivalis and Bacteroides intermedius. The results of this study indicate a significant positive correlation between levels of enzyme capable of degrading N-benzoyl-D,L-arginine-beta-naphthylamide hydrochloride, and subgingival B. gingivalis (r = 0.55). There was a much lower correlation coefficient between this enzyme activity and subgingival B. intermedius (r = 0.26). Statistically significant (p less than 0.01) positive correlations were also demonstrated between total bacterial cell counts and levels of enzymatic activity against N-benzoyl-D,L-arginine-beta-naphthylamide hydrochloride (r = 0.76), N-carbobenzoxy-glycyl-glycyl-L-arginine-beta-naphthylamide hydrochloride (r = 0.72), and glycyl-L-proline-4-methoxy-beta-naphthylamide hydrochloride (r = 0.72), and glycyl-L-proline-4-methoxy-beta-naphthylamide hydrochloride (r = 0.69). There were significant differences in the levels of these three enzymatic activities between sites exhibiting various degrees of clinical severity of gingival inflammation and harboring various proportions of B. gingivalis. The data from this study indicate that measurement of specific enzymatic activities in subgingival samples can be useful in the diagnosis of B. gingivalis-associated periodontitis.

Aged↗
PubMed1988

Microbiological and immunological studies of adult periodontitis in patients with noninsulin-dependent diabetes mellitus.

The subgingival microflora and serum antibody response was examined in periodontitis patients with noninsulin-dependent diabetes mellitus (NIDDM), impaired glucose tolerance (IGT), and normal glucose tolerance (NGT). The predominant cultivable microflora was determined for subgingival plaque sampled from two deep periodontal pockets in each of eight adult periodontitis patients with NIDDM. Indirect immunofluorescence for Bacteroides intermedius, Bacteroides gingivalis, and Haemophilus actinomycetemcomitans was used to examine these same samples as well as 186 additional subgingival plaque samples from 47 patients with moderate to severe generalized periodontitis including 25 subjects with NIDDM, six subjects with IGT, and 16 subjects with NGT. Serum antibody levels to 13 microorganisms including seven oral bacterial species and one nonoral control species were measured by enzyme-linked immunosorbent assays (ELISA) in 377 subjects including 84 normal subjects without periodontal disease, 112 normal subjects with periodontitis, 19 periodontally normal subjects with IGT, 65 periodontitis patients with IGT, 15 periodontally normal subjects with NIDDM, and 82 periodontitis patients with NIDDM. Three hundred eighty-two bacterial isolates were recovered from the eight patients. B. intermedius was the most frequently isolated microorganism constituting 16% of the total isolates followed by Wolinella recta and B. gingivalis, which each accounted for 13% of the total. Streptococcus sanguis was the most prevalent microorganism, which was found in 75% of the sites. Subgingival plaque samples examined by immunofluorescence demonstrate a high prevalence of black-pigmented Bacteroides and suggest that the proportion of B. gingivalis but not B. intermedius is higher in NIDDM with periodontitis than in other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Substituted 2-(2-hydroxyphenyl)benzimidazoles as potential agents for the control of periodontal diseases.

A series of 16 substituted 2-(2-hydroxphenyl)benzimidazoles was synthesized and evaluated in vitro for antibacterial activity against bacteria associated with periodontal diseases. Several compounds demonstrated a high level of activity, in tube dilution assay, against Actinomycetes viscosus and Bacteriodes gingivalis. These results indicate that several of these compounds may serve as topical antibacterial agents for the control of acute marginal inflammatory gingivitis and periodontitis.

Actinomycetales↗
PubMed1987

Capnocytophaga species: increased resistance of clinical isolates to serum bactericidal action.

Capnocytophaga, a newly recognized genus of capnophilic gram-negative bacilli, is part of the normal oral flora. The capacity of Capnocytophaga to cause sepsis and local infections in both immunocompromised and nonimmunocompromised hosts has been documented. Given the recognition that serum resistance may contribute to the virulence of some gram-negative bacteria, we attempted to define the serum sensitivity of clinical isolates of Capnocytophaga from blood and other sites of infection. Whereas nine of nine isolates from human subgingival plaque showed greater than 95% loss of viability under standardized assay conditions, nonoral isolates exhibited variable serum sensitivity. Six of six isolates from blood showed considerable serum resistance (mean survival, 59.7% +/- 38.3%; range, 14.4%-113.3%). Comparison of the electrophoretic mobilities of lipopolysaccharides (LPSs) from sensitive and resistant strains revealed reduced LPS heterogeneity and lower apparent molecular weight among serum-resistant strains. Thus, serum resistance, possibly influenced by LPS structure, may be an important factor contributing to the pathogenic potential of Capnocytophaga spp.

Blood Bactericidal Activity↗