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R J Genco

Publications and source records attributed to R J Genco.

At least 163 records · Page 9Linked to original sources
PubMed1987

Structural determinants of activity of chlorhexidine and alkyl bisbiguanides against the human oral flora.

We assayed chlorhexidine and a series of its analogues, in which the chlorophenyl terminal substituents were replaced with alkyl chains, for their in vitro antimicrobial activity against the Gram-negative and Gram-positive oral bacteria. Changes in antimicrobial activity were correlated with changes in agent structure for identification of structural criteria which may be important in the optimization of agent activity. Chlorhexidine showed substantial antimicrobial activity against the Gram-negative as well as the Gram-positive oral bacteria. The alkyl agents were comparable with chlorhexidine in their activity against Bacteroides gingivalis and Bacteroides intermedius, black-pigmented Gram-negative obligate anaerobes associated with periodontal disease in adults. Alkyl agents alexidine, heptihexidine (1,6-bis-n-heptylbiguanidohexane), hexoctidine (1,8-bis-n-hexylbiguanidoctane), and hexhexidine (1,6-bis-n-hexylbiguanidohexane), as well as chlorhexidine, were active against Actinobacillus actinomycetemcomitans, a Gram-negative organism associated with localized juvenile periodontitis. Hexidecidine (1,10-bis-n-hexylbiguanidodecane) and heptoctidine (1,8-bis-n-heptylbiguanidooctane) were more active, and hexhexidine was as active as chlorhexidine against Fusobacterium nucleatum, also associated with periodontal disease. Seven of the agents were more active than chlorhexidine against Actinomyces species. All test agents were active against Streptococcus mutans, a Gram-positive coccus associated with dental caries. Hexidecidine had activity equal to that of chlorhexidine when evaluated against the entire battery of organisms. Analysis of structure-activity relationships revealed that alkyl chains could replace chlorophenyl groups with retention or improvement of antimicrobial activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗
PubMed1987

Tissue localization of Actinobacillus actinomycetemcomitans in human periodontitis. I. Light, immunofluorescence and electron microscopic studies.

Invasion of periodontal tissues by different bacterial morphotypes has been reported in human periodontitis; however, limited information is available as to prevalence, localization and the bacterial species involved. The present study determined prevalence and gingival localization of Actinobacillus (Haemophilus) actinomycetemcomitans in periodontal lesions of juvenile periodontitis patients. Thirty-five gingival biopsies were obtained from 12 juvenile periodontitis patients at the time of periodontal therapy. One additional control biopsy was obtained from each of two adult periodontally healthy subjects, one adult periodontitis patient and one periodontally healthy monkey (Macaca fosibolius). The biopsies were carefully processed to avoid mechanical introduction of bacteria into the tissues and were examined using light and electron microscopy. Rabbit antisera specific for the three A. actinomycetemcomitans serotypes were used for immunofluorescence microscopic localization of A. actinomycetemcomitans antigens in the gingival sections. Immunofluorescence microscopy showed A. actinomycetemcomitans specific antigens in the gingival tissues of 11 of the 12 juvenile patients examined. None of the control specimens showed evidence of A. actinomycetemcomitans antigens in the gingival connective tissue. One specimen from a periodontally healthy subject and the monkey biopsy, however, showed A. actinomycetemcomitans antigens in bacterial plaque on the surface of the crevicular epithelium. Transmission electron microscopic examination showed microcolonies of small gram-negative rods in the connective tissue, as well as single bacterial cells between collagen fibers and in areas of cell debris. In addition to these extracellular bacterial cells, evidence of bacterial cells was also found within gingival connective tissue phagocytic cells. The data from the present study suggest that the gingival tissue in juvenile periodontitis lesions harbors A. actinomycetemcomitans.

Actinobacillus↗
PubMed1987

Tissue localization of Actinobacillus actinomycetemcomitans in human periodontitis. II. Correlation between immunofluorescence and culture techniques.

Recent immunohistological studies have suggested that Actinobacillus actinomycetemcomitans is present in the gingival tissues in juvenile periodontitis lesions. The present study examined tissue bound A. actinomycetemcomitans by bacterial culture and immunohistological demonstration of antigen in tissue. A total of 14 periodontitis lesions were examined. Eleven biopsies were obtained from gingiva adjacent to A. actinomycetemcomitans infected pockets, while the remaining three control biopsies were obtained from gingiva adjacent to pockets where subgingival A. actinomycetemcomitans infection could not be detected. Each biopsy was hemisected, one half was used for immunofluorescence microscopic examination while the other half was processed for culture of A. actinomycetemcomitans. The latter section was surface-disinfected, repeatedly washed and then minced to release bacteria from within the tissues. Aliquots from the serial washings and the minced tissue suspension were cultured on medium selective for A. actinomycetemcomitans. Surface disinfection and serial washings gradually decreased cultivable A. actinomycetemcomitans in the washings aliquots. Following tissue disruption, an increase in colony-forming units of A. actinomycetemcomitans was seen from eight of the 11 test biopsies. This bacterium could not be detected in washings or minced tissue suspensions from the control biopsies obtained from lesions in which subgingival A. actinomycetemcomitans was previously not detected. A positive correlation was seen between the presence of A. actinomycetemcomitans antigens in the gingival biopsies and; (1) A. actinomycetemcomitans colony-forming units released from the minced tissues (r = 0.90, p = 0.000), as well as; (2) the colony-forming units from the periodontal pocket (r = 0.62, P = 0.017).(ABSTRACT TRUNCATED AT 250 WORDS)

Actinobacillus↗
PubMed1986

Evidence for and partial characterization of three major and three minor chromatographic forms of human neutrophil myeloperoxidase.

Myeloperoxidase (MPO) is an enzyme found in the azurophil granules of neutrophils. Cation-exchange chromatography on carboxymethyl-cellulose previously has been used to demonstrate the heterogeneity of the peroxidase enzymes isolated from human neutrophils. In this study, fast protein liquid chromatography (FPLC) was used to separate and purify three major (I, II, and III) and three minor (IIa, IIIa, IIIb) forms of MPO from isolated neutrophil granules. Purity was confirmed by polyacrylamide gel electrophoresis in the presence of cetyltrimethylammonium bromide (CETAB-PAGE), by crossed immunoelectrophoresis, and by spectral characteristics. All three major forms were indistinguishable by immunodiffusion against rabbit antiserum, scanning spectrophotometry, and amino acid composition. They differed in their elution from a cation-exchange resin, inhibition by 3-amino-1,2,4-triazole, migration rate in CETAB-PAGE, and subunit molecular weight. Subunit molecular weight was examined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). All three major forms appeared to consist of heavy (H), intermediate (M), and light (L) peptides. The M peptide appeared to be derived from the H subunit. All L subunits exhibited a molecular weight of 14,500. The molecular weights for the H subunits varied, and were 60,000, 59,000, and 57,000 for MPO I, II, and III, respectively. The molecular weights for the M peptides were 44,100, 43,000, and 42,000 for MPO I, II, and III, respectively. The treatment of neutrophils, granules, and extracts with protease inhibitors and sodium azide did not block the appearance of three major forms of MPO. Thus, neither protease activity nor MPO autooxidation during extraction and purification procedures is responsible for the appearance of multiple chromatographic forms of MPO derived from human neutrophils.

Amino Acids↗
PubMed1986

Relationships among isolates of oral haemophili as determined by DNA-DNA hybridization.

In order to assess the relationships among strains of the genera Actinobacillus and Haemophilus, DNAs from 50 strains of these genera were isolated and purified. The guanine plus cytosine (G + C) content of DNAs from strains of Haemophilus segnis and Haemophilus parainfluenzae were determined by thermal denaturation. DNA-DNA homologies were measured using labelled probes from one strain representing Haemophilus segnis (strain ATCC 10977), and two strains representing Haemophilus parainfluenzae (strains ATCC 9796 and ATCC 7901). Strains isolated as H. segnis had a G + C content of 39.0 to 42.9% and were 49-92% homologous with the ATCC 10977 DNA probe. All of the strains freshly isolated as H. parainfluenzae were 70-81% homologous with the ATCC 9796 DNA probe and had a G + C content of 34.9 to 38.3%. Strain ATCC 7901 was 11% homologous with the ATCC 9796 DNA probe, had a G + C content of 42.4%, and was 65-78% homologous to DNA from strains identified as Haemophilus aphrophilus and Haemophilus paraphrophilus. From these results we conclude that strain ATCC 7901 is a mislabelled strain of H. paraphrophilus. The results of multiple DNA-DNA hybridizations indicated that separate species designations were appropriate for H. segnis, H. parainfluenzae, Actinobacillus actinomycetemcomitans ("Haemophilus actinomycetemcomitans"), and H. aphrophilus. H. aphrophilus and H. paraphrophilus were closely related organisms and did not fulfill the generally accepted criteria for designation as separate species.

Actinobacillus↗
PubMed1986

5-(Alkylsulfonyl)salicylanilides as potential dental antiplaque agents.

A series of 22 5-(alkylsulfonyl)salicylanilides was synthesized and evaluated for in vitro antibacterial and antiplaque activity against Actinomyces viscosus and Streptococcus mutans, adherent microorganisms implicated in periodontal disease and dental caries. The minimum inhibitory concentrations of 25 salicylanilides (including 5-acyl-, 5-alkyl-, and 5-(alkylsulfonyl)-4'-bromo- and -4'-(trifluoromethyl)salicylanilides) were found to correlate (r = 0.94) with estimated log D values. Several salicylanilides, such as 5-(decylsulfonyl)- and 5-(dodecylsulfonyl)-4'-(trifluoromethyl)salicylanilides (15 and 19) were found to exhibit high levels of in vitro antibacterial and antiplaque activity against A. viscosus and S. mutans.

Actinomyces↗
PubMed1986

Topical antimicrobial therapy and diagnosis of subgingival bacteria in the management of inflammatory periodontal disease.

Bacterial specificity in human periodontal diseases suggests the possibility of diagnosing and treating periodontitis as specific infections and using microbiological diagnostic means to evaluate the efficacy of periodontal therapy. In a series of clinical trials, the usefulness of topical antimicrobial agents in combination with surgical and non-surgical conventional periodontal therapy were tested. The healing result was estimated by monitoring probing attachment levels (PAL). The usefulness of clinical and microbiological parameters to evaluate post-treatment healing result was tested. 9 of the patients exhibiting sites with recurrent periodontal disease were then evaluated for clinical and microbiological parameters to define accurate means to differentiate between active and inactive periodontal disease. The results showed that the frequency of periodontal lesions with significant loss of PAL after treatment was less in patients treated with antimicrobial agent. Specific microbiological parameters showed stronger correlation than clinical parameters with gain and/or loss of PAL post-treatment. Thus Actinobacillus actinomycetemcomitans and Bacteroides gingivalis occurred in periodontal lesions with progressing disease after treatment, but were rarely detected in samples from pockets of the same depths which did not exhibit further loss of PAL over a study period of 1 year. This study points to the usefulness of topical antimicrobial agent as an adjunct to mechanical subgingival debridement in the treatment of periodontitis in adults. The results also indicate the utility of diagnostic microbiology in the assessment of periodontal disease activity post-treatment.

Acetrizoic Acid↗
PubMed1986

Analysis of data from clinical studies of localized juvenile periodontitis.

Data from 27 subjects with localized juvenile periodontitis were used to compute estimates of the intraclass correlation coefficient for initial periodontal pocket depth measurements and total subgingival Actinobacillus actinomycetemcomitans counts, and for changes from pre- to post-treatment in periodontal pocket depth, probing attachment level and Actinobacillus actinomycetemcomitans counts. The estimates for the clinical parameters were considerably higher than those found in a similar study of adult periodontitis. On the average, the estimates for the intraclass correlation coefficients for Actinobacillus actinomycetemcomitans counts did not differ markedly from the corresponding estimates for the clinical parameters. Although the results of this study indicate that the major component of variability in parameters commonly used in studies of periodontal disease can be attributed to site-specific factors, sites within subjects cannot be considered statistically independent. For the analysis of data arising from studies of periodontal disease, it is recommended that statistical techniques, like the nested mixed effects analysis of variance model be employed, which account for this dependence. These techniques will allow meaningful biological questions concerning site-specific phenomenon to be answered. However, changes in clinical and microbiological parameters, when therapeutic measures are employed on localized juvenile periodontitis patients, are often dramatic enough to allow informal data presentation.

Actinobacillus↗
PubMed1986

Oxidative and nonoxidative killing of Actinobacillus actinomycetemcomitans by human neutrophils.

Actinobacillus actinomycetemcomitans is a facultative gram-negative microorganism which has been implicated as an etiologic agent in localized juvenile periodontitis and in subacute bacterial endocarditis and abscesses. Although resistant to serum bactericidal action and to oxidant injury mediated by superoxide anion (O2-) and hydrogen peroxide (H2O2), this organism is sensitive to killing by the myeloperoxidase-hydrogen peroxide-chloride system (K.T. Miyasaki, M.E. Wilson, and R.J. Genco, Infect. Immun. 53:161-165, 1986). In this study, we examined the sensitivity of A. actinomycetemcomitans to killing by intact neutrophils under aerobic conditions, under anaerobic conditions, and under aerobic conditions in the presence of the heme-protein inhibitor sodium cyanide. Intact neutrophils killed opsonized A. actinomycetemcomitans under aerobic and anaerobic conditions, and the kinetics of these reactions indicated that both oxidative and nonoxidative mechanisms were operative. Oxidative mechanisms contributed significantly, and most of the killing attributable to oxidative mechanisms was inhibited by sodium cyanide, which suggested that the myeloperoxidase-hydrogen peroxide-chloride system participated in the oxidative process. We conclude that human neutrophils are capable of killing A. actinomycetemcomitans by both oxygen-dependent and oxygen-independent pathways, and that most oxygen-dependent killing requires myeloperoxidase activity.

Actinobacillus↗
PubMed1986

Killing of Actinobacillus actinomycetemcomitans by the human neutrophil myeloperoxidase-hydrogen peroxide-chloride system.

Actinobacillus actinomycetemcomitans is a facultative gram-negative coccobacillus associated with periodontal disease and nonoral infections. This organism is resistant to serum bactericidal mechanisms but is nevertheless killed by human neutrophils under aerobic and anaerobic conditions. Most of the killing attributable to oxidative mechanisms is inhibited by sodium cyanide, which suggests that the myeloperoxidase-hydrogen peroxide-chloride (MPO-H2O2-Cl-) system may be a key factor in the oxidative killing process. In this report, we examine whether the isolated MPO-H2O2-Cl- system is bactericidal against A. actinomycetemcomitans. We found that three major chromatographic forms of MPO were capable of killing A. actinomycetemcomitans at sublethal concentrations of H2O2 and that both catalase-positive and catalase-negative strains of this organism were sensitive to killing by the MPO-H2O2-Cl- system. We conclude that the isolated MPO-H2O2-Cl- system is bactericidal for A. actinomycetemcomitans independent of other neutrophil granule constituents and may be an important component of the oxygen-dependent bactericidal activity of the neutrophil with respect to this periodontopathic organism.

Blood Bactericidal Activity↗
PubMed1986

Purification and properties of hemagglutinin from culture supernatant of Bacteroides gingivalis.

The hemagglutinating factor (hemagglutinin) of Bacteroides gingivalis was prepared from the supernatant of a 5-day diffusate broth culture by ammonium sulfate precipitation and column chromatography with a hydrophobic column of Phenyl-Sepharose CL-4B, DEAE-Sephadex A-50, and Sephadex G-100 gel filtration. The hemagglutinating activity of the preparation was 53.3 times higher than that of ammonium sulfate precipitate. In electron microphotographs, hemagglutinin appears to have a vesicle or tubelike structure. The hemagglutinating activity of intact cells was completely destroyed by heating at 100 degrees C for 10 min, but the activity of extracted hemagglutinin was heat stable. The activity of hemagglutinin was inhibited by L-arginine and L-lysine and partially inhibited by phospholipase D, but it was not affected by proteolytic enzymes, neuraminidase, hyaluronidase, lipase, phospholipase A and C, or sugars. The B. gingivalis hemagglutinin appeared to be comprised mainly of a 40,000-molecular-weight material. The Fab fragment of immunoglobulin G prepared from rabbit antiserum to whole cells of B. gingivalis and monoclonal antibody against the hemagglutinin bound to the cell surface and inhibited the hemagglutinating activity of both the cells and the purified hemagglutinin.

Amino Acids↗
PubMed1986

The use of monoclonal antibodies to detect Bacteroides gingivalis in biological samples.

Hybridomas were established which produce monoclonal antibodies specific for Bacteroides gingivalis, a pathogen associated with human periodontal disease. Spleen cells from BALB/c mice immunized with formalinized B. gingivalis were fused with Sp2/0-Ag14 myeloma cells. Of 1,050 wells with positive growth, 60 contained antibody reactive with the immunizing strain of B. gingivalis by enzyme-linked immunosorbent assay. Expansion of these cultures and cloning by limited dilution resulted in 28 clones which reacted with B. gingivalis but not with other orals and nonoral black-pigmented Bacteroides species or any of 29 representative strains of other oral bacteria. Of these 28 clones, 14 were also specific for B. gingivalis by indirect immunofluorescence microscopy. One clone, BBG-12 producing immunoglobulin G2b(kappa), was chosen to identify B. gingivalis in subgingival plaque because of its high reactivity in indirect immunofluorescence assays. This antibody reacted strongly with all 17 representative B. gingivalis strains obtained from diverse sources. Furthermore, when this reagent was applied to subgingival plaque samples, B. gingivalis was stained with high specificity and low background fluorescence, indicating that it may be useful for clinical identification of this organism.

Antibodies, Bacterial↗
PubMed1986

Antimicrobial properties of hydrogen peroxide and sodium bicarbonate individually and in combination against selected oral, gram-negative, facultative bacteria.

The topical application of hydrogen peroxide (H2O2) and sodium bicarbonate (NaHCO3), individually and in combination, has been used empirically in the treatment of periodontal diseases. In this study, we examined both minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of these disinfectants individually and in combination against selected facultative, Gram-negative oral bacteria in a microtiter dilution assay. The bacteria studied included Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Eikenella corrodens, and Capnocytophaga gingivalis. These bacteria exhibited MBC (one hr) values ranging from 75 mumol/L to greater than 10 mmol/L and MIC from less than 5 to 500 mumol/L for H2O2. The tested bacteria exhibited MIC values for NaHCO3 of from 23 to 182 mmol/L, and the MBC (one hr) exceeded 728 mmol/L for most of the strains examined. At sublethal (sub-MIC) concentrations, sodium bicarbonate antagonized the ability of H2O2 to inhibit bacterial growth in MIC assays, but sublethal concentrations of H2O2 had no effect on the MIC values of NaHCO3. Lethal concentrations of H2O2 and NaHCO3 exhibited synergistic antimicrobial activity in combination in one-hour bactericidal assays. Since the bactericidal properties of these antimicrobial agents are synergistic, we conclude that it may be rational to use them in combination to treat certain forms of periodontal disease. Also, lower and perhaps safer concentrations of H2O2 can be used in combination with NaHCO3 when oxidative antimicrobial chemotherapy is indicated.

Actinobacillus↗