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Biomedical subjects

G C Armitage

Publications and source records attributed to G C Armitage.

At least 37 records · Page 2Linked to original sources
PubMed1991

Multicenter evaluation of tetracycline fiber therapy: II. Clinical response.

The safety and efficacy of periodontal disease treatment by intrapocket placement of tetracycline (TC) fibers was investigated in a 60-day multicenter study conducted by selecting 4 sites in each subject with 6-10 mm pockets that bled on probing. Sites were randomly assigned to 1 of 4 test groups: TC fiber therapy, scaling, control fiber (fibers without drug), or untreated. TC fibers and control fibers were placed to fill the pocket and were maintained with a cyanoacrylate adhesive for 10(+/- 2) d. Scaling was performed for a minimum of 5 min under local anesthesia. Following initial tooth cleaning procedures, pocket depth, attachment level and bleeding on controlled-force probing were measured at baseline and at 30 d, and 60 d following therapy. Analysis of data from 107 subjects who had complete clinical data sets indicated that TC fiber therapy significantly decreased pocket depth, increased attachment level, and decreased bleeding on controlled-force probing to a greater extent than observed in all other test groups including scaling. These effects were greater than, and in addition to, effects that occurred due to prophylaxis and improved home care. No serious adverse side-effects attributed to TC fiber therapy were observed. No TC fiber-treated sites abscessed and superinfection was not noted. A transient redness at fiber removal was seen at 21% of the sites. Although fibers were placed without anesthesia, mild pain on initial placement was infrequent (19%) and abated rapidly. The results indicate that TC fiber placement provides a safe and effective means for treatment of periodontal infections.

Adult↗
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

Effects of ascorbic acid depletion and supplementation on periodontal health and subgingival microflora in humans.

This study describes the relationship between varying ascorbate intake, periodontal status, and subgingival microflora as part of a multidisciplinary investigation of ascorbic acid (AA) metabolism in young men housed for 13 weeks in a nutrition suite that provided controlled periods of ascorbic acid depletion and repletion. Twelve medically healthy non-smoking men, aged 25 to 43 years, ate a rotating four-day diet adequate in all nutrients except ascorbic acid. Following an initial baseline period during which the subjects received 250 mg AA/day, the subjects received 5 mg AA/day for a 32-day depletion period. Eight of the 12 subjects participated in a subsequent 56-day repletion period designed to replace the reduced body AA pool slowly. Plasma and leukocyte ascorbate levels, Plaque Index, Gingival Index, probing depths, and attachment level were monitored at the beginning and end of the depletion and repletion periods. Subgingival plaque samples were obtained and examined for selected organisms by indirect immunofluorescence microscopy. A uniform oral hygiene program was reinforced after each examination. Ascorbate concentrations in plasma and leukocytes responded rapidly to changes in vitamin C intake. There were no significant changes in plaque accumulation, probing pocket depth, or attachment level during the study. In contrast, gingival bleeding increased significantly after the period of AA depletion and returned to baseline values after the period of AA repletion. However, no relationship could be demonstrated between either the presence or proportion of target periodontal micro-organisms and measures of bleeding or ascorbate levels.

Actinomyces viscosus↗
PubMed1990

Effect of Actinobacillus actinomycetemcomitans, Wolinella recta and Bacteroides gingivalis on the viability of retinoic acid-induced and dimethyl sulfoxide-induced HL-60 cells.

We studied the interactions between viable and heat-killed, opsonized and unopsonized periodontopathic bacteria with both uninduced and induced HL-60 promyelocytic leukemia cells. The cells were induced to differentiate into granulocyte-like cells by incubation with retinoic acid (RA) or dimethyl sulfoxide (DMSO). When unopsonized, Wolinella recta ATCC 33228 significantly suppressed the net proliferation of uninduced HL-60 cells, Actinobacillus actinomycetemcomitans strain Y4 was markedly lethal to the cells, and Bacteroides gingivalis ATCC 33277 had no effect. Unopsonized and opsonized A. actinomycetemcomitans and W. recta had equally potent lethal effects on induced HL-60 cells. Unopsonized B. gingivalis was not lethal to the induced cells in the dose used (100 bacteria/HL-60 cell), but opsonized B. gingivalis was lethal, especially in the first 24 h. The killing effects of A. actinomycetemcomitans and W. recta were largely eliminated if they were heated (56 degrees C, 30 min) before being added to the induced HL-60 cells. RA-induced HL-60 cells were more sensitive to the lethal effects of A. actinomycetemcomitans and W. recta than were DMSO-induced cells. The results suggest that the HL-60 cell line may be a useful model for studying granulocyte-bacteria interactions.

Actinobacillus↗
PubMed1990

Interaction of gram-negative periodontal pathogens with retinoic acid-induced and dimethyl sulfoxide-induced HL-60 cells.

As a first step toward elucidating the reasons for differences among periodontal pathogens in their cytotoxic effects on HL-60 cells, we used transmission electron microscopy to examine morphological aspects of granulocyte-bacteria interactions. Unopsonized Actinobacillus actinomycetemcomitans strain Y4 and Bacteroides gingivalis ATCC 33277 adhered to, and were phagocytosed by, retinoic acid-induced and dimethyl sulfoxide-induced HL-60 cells. In contrast, there was only minimal interaction between Wolinella recta ATCC 33238 and these induced granulocyte-like cells. Only isolated examples of adherence of W. recta to HL-60 cells were seen. In specimens prepared for routine transmission electron microscopy, ingested W. recta were not observed. In immunogold experiments, phagocytosed W. recta were noted, but only rarely. Opsonization of A. actinomycetemcomitans, B. gingivalis and W. recta with specific antisera appeared to increase their level of interaction with the HL-60 cells. We suggest that the HL-60 cell line may be useful in elucidating structure-function relationships between human neutrophil-like cells and putative periodontopathogens.

Actinobacillus↗
PubMed1990

Assessment of the efficacy of a nonsteroidal anti-inflammatory drug, Naprosyn, in the treatment of gingivitis.

A double-blind, placebo-controlled trial was conducted to determine the effects of the nonsteroidal anti-inflammatory drug Naprosyn (naproxen) on gingival inflammation. The enrollment of 114 patients provided 102 patients valid for efficacy evaluation, each having a mean gingival index (GI) score of 1.5 or greater at test-teeth sites. Patients were given oral Naprosyn 500 mg b.i.d. or placebo for 30 days. At 28 d, full-mouth prophylaxis was performed. Gingival index, modified sulcular bleeding index (SBI), and plaque index (PII) scores were taken at baseline, at 28 d, and at 30 d. When the 28-d index measurements were compared to baseline, the drug had no significant effect on plaque index scores or gingival inflammation. Statistically, Naprosyn enhanced the resolution of gingival inflammation following removal of microbial plaque. Thus, although this drug does not suppress the inflammation-inducing properties of plaque, Naprosyn may enhance recovery following plaque removal.

Adult↗
PubMed1989

Mucosal epithelial cells and Langerhans cells are targets for infection by the immunosuppressive type D retrovirus simian AIDS retrovirus serotype 1.

Simian acquired immune deficiency syndrome (SAIDS) caused by the type D retrovirus SRV-1 results in opportunistic infections and a spectrum of oral lesions similar to those seen in humans with AIDS. To better understand the pathogenesis of these oral lesions we have retrospectively examined the oral mucosa from ten rhesus monkeys that died with SAIDS and prospectively examined the oral mucosa of ten additional animals inoculated with SRV-1 to determine at what time, and in what cells SRV-1 infection of the oral mucosa occurs. Using single and double label immunohistologic techniques, and electron microscopy we detected SRV-1 in clusters of oral epithelial cells and rare Langerhans cells as early as 1 month postinoculation.

Animals↗
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↗
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↗
PubMed1982

Relationship between the percentage of subgingival spirochetes and the severity of periodontal disease.

The purpose of this study was to determine the correlations between various clinical assessments of inflammatory periodontal disease and the percentage of motile bacteria in the subgingival flora of sites representing widely varying states of periodontal disease. Darkfield microscopy was used to determine the percentage of spirochetes and other motile bacteria at two sites from each of 60 volunteers. For each site the following clinical assessments were recorded: Plaque Index (PII), gingival exudate (GE), Gingival Index (GI), bleeding tendency (BT), pocket depth (PD), connective tissue attachment loss (AL) and Periodontal Disease Index (PDI). Statistically significant (P less than 0.001) positive correlations (r) were found between the percentage of subgingival spirochetes and PII (r=0.54), GE (r=0.61), GI (r=0.57), BT (r=0.59), PD (r=0.56), AL (r=0.56) and PDI (r=0.61). Clinically healthy sites harbored much lower percentages of motile bacteria than did clinically disease sites. Most of the observed variation in the percentage of motile bacteria could be accounted for by variations in the percentage of spirochetes. The most significant increases in the relative percentages of subgingival spirochetes occurred when bleeding upon probing was observed as a sign of inflammation and/or when pocket depth and attachment loss exceeded 3 mm.

Adult↗
PubMed1980

Use of dental xeroradiographs in periodontics. Comparison with conventional radiographs.

An experimental intraoral dental xeroradiographic system was evaluated for its ability to image structures important in periodontal radiographic interpretation. On consenting dental patients, similar x-ray projections were made on (1) conventional film radiography and (2) experimental dental xeroradiographs. The resultant images were compared visually. In all categories examined the information provided by xeroradiography was either equal to or greater than that provided by conventional film radiographs. Intraoral dental xeroradiography appears to be a highly accurate, low-radiation, rapid, and convenient alternative to conventional intraoral radiography.

Alveolar Process↗