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Biomedical subjects

S Renvert

Publications and source records attributed to S Renvert.

At least 37 records · Page 2Linked to original sources
PubMed1997

Modification of cystatin C activity by bacterial proteinases and neutrophil elastase in periodontitis.

AIM: To study the interaction between the human cysteine proteinase inhibitor, cystatin C, and proteinases of periodontitis associated bacteria. METHODS: Gingival crevicular fluid samples were collected from discrete periodontitis sites and their cystatin C content was estimated by enzyme linked immunosorbent assay (ELISA). The interaction between cystatin C and proteolytic enzymes from cultured strains of the gingival bacteria Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans was studied by measuring inhibition of enzyme activity against peptidyl substrates, by detection of break down patterns of solid phase coupled and soluble cystatin C, and by N-terminal sequence analysis of cystatin C products resulting from the interactions. RESULTS: Gingival crevicular fluid contained cystatin C at a concentration of approximately 15 nM. Cystatin C did not inhibit the principal thiol stimulated proteinase activity of P gingivalis. Instead, strains of P gingivalis and P intermedia, but not A actinomycetemcomitans, released cystatin C modifying proteinases. Extracts of five P gingivalis and five P intermedia strains all hydrolysed bonds in the N-terminal region of cystatin C at physiological pH values. The modified cystatin C resulting from incubation with one P gingivalis strain was isolated and found to lack the eight most N-terminal residues. The affinity of the modified inhibitor for cathepsin B was 20-fold lower (Ki 5 nM) than that of full length cystatin C. A 50 kDa thiol stimulated proteinase, gingipain R, was isolated from P gingivalis and shown to be responsible for the Arg8-bond hydrolysis in cystatin C. The cathepsin B inhibitory activity of cystatin C incubated with gingival crevicular fluid was rapidly abolished after Val10-bond cleavage by elastase from exudate neutrophils, but cleavage at the gingipain specific Arg8-bond was also demonstrated. CONCLUSIONS: The physiological control of cathepsin B activity is impeded in periodontitis, owing to the release of proteinases from infecting P gingivalis and neutrophils, with a contribution to the tissue destruction seen in periodontitis as a probable consequence.

Bacteria↗
PubMed1997

Clinical and microbiological effects of subgingival antimicrobial irrigation with citric acid as evaluated by an enzyme immunoassay and culture analysis.

The purpose of the present study was to compare an enzyme immunoassay with culture samples from untreated and non-surgically treated periodontal pockets and to assess the clinical and microbiological effects of citric acid irrigation as a supplement to scaling and root planing. The enzyme immunoassay used in this study is a chairside diagnostic tool aimed at identifying the presence of P. gingivalis, P. intermedia, and A. actinomycetemcomitans. Six sites with pocket depths > or = 6 mm in each of 16 patients were monitored for 24 weeks using clinical and microbiological parameters. In two out of the six sites, scaling and root planing was supplemented with subgingival citric acid irrigation of the pocket after completion of the mechanical treatment. The sensitivity of the immunoassay in relation to culture was calculated to 85.5% and the specificity to 90.2%. The immunoassay corresponded to a detection level of 10(4) as estimated by culture. Sites treated with a combination of scaling and irrigation with citric acid demonstrated a similar healing pattern as sites treated with scaling and root planing alone. The profile of the marker bacteria was almost parallel for the two groups. The results of this investigation thus indicated that the immunoassay can be used as a screening tool for selected periodontal pathogens and that adjunctive irrigation with citric acid has no measurable clinical or microbiological effects.

Adult↗
PubMed1997

Effect of xylitol in an enzyme-containing dentifrice without sodium lauryl sulfate on mutans streptococci in vivo.

The aim of this investigation was to compare the effect of an enzyme-containing dentifrice without sodium lauryl sulfate but with addition of xylitol (Zendium Dentine) on mutans streptococci (MS) in saliva and dental plaque with that of the same dentifrice without xylitol. The subjects were divided into a test group, using a dentifrice with 10% xylitol (part A) or 5% xylitol (part B), and a control group, using a dentifrice without xylitol, for 3 months. In part A the MS counts in saliva and plaque were significantly lower in the xylitol group (n = 50) than in the control group (n = 57) (P < 0.01 and P < 0.001, respectively). In part B (n = 89 + 91), evaluating MS counts in saliva only, no significant difference was found. Thus, this study demonstrated I) that addition of 10% xylitol to an enzyme-containing dentifrice without sodium lauryl sulfate has an inhibitory effect on MS counts in saliva and dental plaque, and 2) that the inhibitory effect seems to be dose-dependent.

Adult↗
PubMed1996

Supracrestal bone growth around partially inserted titanium implants in dogs. A pilot study.

8 titanium implants (Nobel Biocare, Göteborg, Sweden) were inserted into edentulous lower premolar areas of 4 dogs so that 6 threads of the implant protruded from the bone crest. Newly-developed perforated dome-shaped titanium space maintainers were fixed to the implant with cover screws. Autogenous bone fragments were placed under the space maintainers. On one side of the arch, the space maintainer was covered with a non resorbable cell occluding barrier. The implant/space maintainers were submerged under coronally positioned flaps. Following a 3-month healing period, there was a mean gain of new bone amounting to 2.5 mm for all specimens. A greater height of bone was found for those sites in which an ePTFE membrane was used; 3.1 mm vs. 1.9 mm (p < 0.05). This study demonstrated the potential of coronal bone growth of the alveolar bone in a protected space around crew implants with exposed treads when placed in the dog.

Alveolar Process↗
PubMed1996

Immunohistological characteristics of periodontal lesions associated with Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans infections.

In this study, various phenotypes of infiltrating cells in the periodontium adjacent to pockets harboring Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were evaluated. Furthermore, the pattern of class II antigen expression in the periodontal tissues was determined. Eight lesions were associated with the presence of P. gingivalis and 12 with A. actinomycetemcomitans. Predominant cells in the inflammatory infiltrate were T- and B-cells. In most biopsies T-cells dominated over B-cells. The proportion of P. gingivalis, but not of A. actinomycetemcomitans, was positively correlated to the total number of infiltrating cells in the tissue. A. actinomycetemcomitans sites demonstrated somewhat lower proportions of CD3+, CD4+ and CD19+ cells than P. gingivalis sites. However, the tendency of decreasing CD4+/CD8+ ratio with increasing number of A. actinomycetemcomitans indicates a local imbalance in immunoregulation. The frequency of class II antigen expression of both mononuclear and epithelial cells, a sign of immunological activation, was generally high.

Adult↗
PubMed1996

Histological and microbiological aspects of ligature-induced periodontitis in beagle dogs.

This study was designed to investigate, using 6 beagle dogs, the levels of selected putative pathogens in healthy sites, in gingivitis sites, and in sites with histologically confirmed attachment loss. Levels of attachment loss increased with increasing periods of ligation and reached a maximum of 0.15 mm at 57 days. Both histological attachment level and histological pocket depth were found to vary significantly with health/disease status (p < 0.0001). Higher numbers of total colony-forming units were seen for ligated sites than for healthy and gingivitis sites. Levels of Porphyromonas gingivalis and Prevotella intermedia also changed significantly with health/disease status (p < 0.001). These organisms showed their greatest increases at the time of the most intense attachment loss. Higher levels of Fusobacterium nucleatum were seen in the gingivitis sites than in healthy or ligated sites. Low levels of Campylobacter rectus and Capnocytophaga spp. were detected throughout. The morphometric microbiological analysis revealed unexpectedly high %s of motile rods, while spirochetes were found in very low %s. The total number of bacterial cells detected using phase contrast microscopy was not found to vary significantly. None of the morphotypes were demonstrated as showing significant changes with health/disease status.

Analysis of Variance↗
PubMed1996

Treatment of periodontal disease based on microbiological diagnosis. Relation between microbiological and clinical parameters during 5 years.

The purpose of this study was to assess the clinical effect of treatment aimed to suppress Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis below detection level and Prevotella intermedia below 5% of the cultivable periodontal pocket flora. Sixteen patients and a total of 111 periodontal pockets with probing depth > or = 6 mm were included in the study. Twelve patients and a total of 77 sites completed the 5-year study. The results demonstrated clinical improvement of probing depth and gain of clinical attachment level of 3.4 mm and 1.2 mm, respectively. Treatment to eliminate indicator bacteria continued for 3 years before the aim was fulfilled. In order to eliminate A. actinomycetemcomitans from a majority of the sites, a combination of surgery and generalized tetracycline treatment was performed. A recolonization or regrowth of the indicator bacteria exceeding detection levels took place in several sites. The presence of A. actinomycetemcomitans. P. gingivalis, and P. intermedia, alone or in combination, correlated with attachment level change on the individual level. No such correlation was obtained by using presence of plaque, bleeding on probing, or three other bacteria (Campylobacter rectus, Eikenella corrodens, and Fusobacterium nucleatum) not used as treatment goal markers.

Adult↗
PubMed1996

Treatment of periodontal disease based on microbiological diagnosis. A 5-year follow-up on individual patterns.

Sixteen patients with advanced periodontitis (more than 3 sites with a probing depth > or = 6 mm) were treated with the aim of eliminating Actinobacillus actinomyce-temcomitans and Porphyromonas gingivalis and reducing Prevotella intermedia below 5% of the total viable count. The patients were followed clinically and microbiologically for over 5 years and showed a highly individual pattern with respect to presence of indicator bacteria, type of treatment needed to accomplish treatment goals, clinical response, and bacterial and disease recurrencies. The results of this study suggest that presence of the indicator bacteria in microbial samples taken after treatment may identify patients at risk for recurrent periodontitis.

Adult↗
PubMed1995

Comparison between 3 triclosan dentifrices on plaque, gingivitis and salivary microflora.

3 triclosan-containing dentifrices were compared in a 6-month, unsupervised tooth brushing study. The effects on plaque, gingival bleeding and certain salivary micro-organisms (mutans streptococci, lactobacilli, total counts of streptococci and total counts of micro-organisms) were evaluated. 123 subjects were divided into 4 groups according to severity of gingival bleeding index. 112 subjects completed the study. Following a 4-week pre-experimental period, using a sodium monofluorophosphate dentifrice (placebo), the subjects were assigned to use one of 3 triclosan-containing dentifrices, available on the Swedish market: Colgate Paradent (a triclosan/copolymer dentifrice) (n = 26); Pepsodent Gum Health (a triclosan/zinc citrate dentifrice) (n = 31); Dentosal Friskt Tandkött (a triclosan/pyrophosphate dentifrice) (n = 28); or to continue with the placebo (n = 27). The results revealed that Colgate Paradent reduced baseline plaque values by 39% (Quigley and Hein) over the 6-month experimental period. The corresponding values for the other modalities were: a reduction of 6% for Pepsodent Gum Health, an increase of 5% for Dentosal Friskt Tandkött, and an increase of 2% for placebo. A significant difference in the plaque levels (p < 0.05) was found between Colgate Paradent and Pepsodent Gum Health and between Colgate Paradent and placebo. The gingival bleeding index was improved in all 4 groups. A significant difference (p < 0.05) was found with respect to bleeding between Colgate Paradent and placebo (p < 0.05) at the 3-month registration. A statistically significant increase over time in total number of streptococci and total colony forming units were found for the Dentosal, Pepsodent and placebo groups, but not for Colgate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Detection of Porphyromonas gingivalis in gingival exudate by a dipeptide-enhanced trypsin-like activity.

Porphyromonas gingivalis in subgingival plaque is an important risk factor for future periodontal attachment loss in susceptible adults. The elimination of P. gingivalis is usually concomitant with a healing process. Therefore, it should be valuable to have an easy chairside method to follow the effect of periodontal treatment on P. gingivalis detection as well as on its eventual reappearance during the maintenance period. We have previously reported the stimulation of amidolytic activity of P. gingivalis by the addition of glycyl-glycine to the assay buffer. In this study we determined the proportions of P. gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Capnocytophaga spp, Campylobacter rectus, and Eikenella corrodens by cultivation technique and the amidolytic activity, using N-benzoyl-L-arginine-p-nitroanilide (BAPNA) as substrate, in gingival exudate before and during a 3-year treatment and maintenance period. P. gingivalis was the only species yielding a high and persistent correlation to stimulated amidolytic activity (P values < or = 0.0001) on both site (r = 0.5) and subject (r = 0.8) level. Testing pure cultures of suggested periodontal pathogens for effect of glycyl-glycine on amidolytic activity, we found that of P. gingivalis to be 5.9-fold increased. The amidolytic activity of Treponema denticola was only slightly stimulated (ratio with/without glycyl-glycine = 1.2) and that of Capnocytophaga slightly inhibited (ratio with/without glycyl-glycine = 0.8). The outcome of this study has the potential to be used for the development of a simple, rapid, and inexpensive assay for a qualitative and quantitative determination of P. gingivalis in gingival crevicular fluid.

Adult↗
PubMed1993

Microbial associations in periodontitis sites before and after treatment.

Duplicate samples from 110 periodontal sites of 6 mm or more pocket depth in 16 patients were analyzed for the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Capnocytophaga spp., Campylobacter rectus, Eikenella corrodens and Fusobacterium nucleatum. The sites were sampled before and after nonsurgical periodontal treatment. No statistically significant associations were found before treatment between any of the analyzed species. After treatment, statistically significant associations were found between E. corrodens and all the other species, F. nucleatum and P. intermedia; Capnocytophaga spp. and C. rectus; P. intermedia vs Capnocytophaga spp. and P. gingivalis; and C. rectus vs Capnocytophaga spp. and A. actinomycetemcomitans. Some of these associations could be explained either by patient-related factors or site-related characteristics such as the pocket depth. The proportion of P. gingivalis seemed to be unrelated to the proportion of P. intermedia in the samples. If one of the analyzed microbes was found in one of the sampled pockets in a patient, the probability of finding that microbe in all the sampled sites in the same patient before treatment was more than 50%. This probability was reduced after treatment for many species, especially P. gingivalis, which showed a probability of zero. The probability of detecting a bacterial species on at least one additional site if it was present on one in the same individual was nearly 100%, both before and after treatment, for all species studied. This study has shown several potential microbial associations in the subgingival plaque flora of deep periodontal pockets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Reflectance method for simple determination of proteinase activity in microliter samples of a complex serum-like fluid.

A technique using an optical instrument, a reflectometer, for quantitative determination of proteinase activity in microliter samples of complex serum-like fluids, e.g., crevicular exudate from single sites, was developed. The technique allowed the use of various proteins as enzyme substrate. The reflectometer measures the mass of a layer, such as protein, adsorbed to a reflecting surface. This is done by measuring the reflected light intensity of the p-polarized light beam on a surface. We used methylized silicon surfaces that were coated with fibrinogen, alpha 2-macroglobulin, or hemoglobin as enzyme substrates. The test solution was incubated overnight in a basin made in an agar gel applied on the top of the protein-coated surface. In 82 exudates from periodontitis sites, with pocket depths greater than or equal to 6 mm, fibrinogenolytic activity corresponding to 1 microgram ml-1 of trypsin and pronase P was found in 20% of the samples.

Endopeptidases↗
PubMed1992

Comparative study of subgingival microbiological sampling techniques.

The presence of specific bacteria in subgingival plaque has been used as an indicator of active periodontal disease. The technique of subgingival sampling may conjecturally influence the identification and enumeration of microorganisms reported. In this study, paper point sampling and scaler sampling are compared. Subgingival samples using both methods were taken from three surfaces in each of 12 patients at the following time points: at each of two appointments one week apart before treatment and at each of two appointments 12 and 13 weeks following treatment. Microbiological analyses were undertaken to determine the total number of colony forming units, the proportions of suspected periodontal pathogens, and the number of spirochetes using phase contrast microscopy. Significantly higher numbers of colony forming units and spirochetes were found for paper point sampling both before and after treatment.

Adult↗
PubMed1991

Variance in recovery of periodontitis-associated bacteria caused by sampling technique and laboratory processing.

The influence of sampling procedure and of laboratory processing on the recovery of Bacteroides gingivalis, Bacteroides intermedius, and Actinobacillus antinomycetemcomitans from periodontitis sites was evaluated. Thirty-three adult subjects with severe periodontitis participated in the study. In all, 462 samples from 81 sites were examined. The samples were taken using the paper point technique. The cultivations were performed by use of enriched Brucella agar for determination of total colony-forming units and Bacteroides species, and trypticase soy bean agar for determination of A. actinomycetemcomitans. The risk of getting a false negative result was 4% for B. gingivalis, 20% for B. intermedius, and 38% for A. actinomycetemcomitans. It was considerably reduced if duplicate samples were taken. The sampling procedure alone explained up to 98% of the false-negative results.

Adult↗
PubMed1991

Stimulation of proteinase and amidase activities in Porphyromonas (Bacteroides) gingivalis by amino acids and dipeptides.

Proteolytic enzymes from the organism Porphyromonas gingivalis are believed to be involved in the development of periodontitis. Studies on both crude extracts and purified trypsinlike enzymes from this organism indicate that substantial stimulation of both amidase and proteinase activities can be obtained during incubation with glycine-containing compounds. We postulate that P. gingivalis may have developed this unusual property to take advantage of the glycine-rich environment which occurs during the periodontitis-associated degradation of gingival collagen. The finding of such a stimulation in crevicular fluids from discrete periodontal sites has been correlated with the presence of P. gingivalis and could be utilized for the early detection of infection by this organism during the onset of periodontitis.

Amidohydrolases↗
PubMed1990

Effect of root debridement on the elimination of Actinobacillus actinomycetemcomitans and Bacteroides gingivalis from periodontal pockets.

The aims of this 6-month longitudinal study were: (1) to investigate to what extent root debridement of pockets in adult periodontitis will reduce the subgingival presence of Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and some other bacterial groups; (2) to relate the microbiological results following debridement to clinical measurements of healing. 16 patients and a total of 111 periodontally involved sites with probing depth greater than or equal to 6 mm served for the study. Duplicate subgingival microbial samples and duplicate clinical recordings were obtained 1 week apart at baseline and at 6 months following supra- and subgingival debridement. The results demonstrated reductions of the mean total viable counts and reductions of the mean counts of several of the cultured groups of micro-organisms coupled with significant improvements of mean clinical measurements. B. gingivalis was eliminated from a majority of infected subgingival sites. A. actinomycetemcomitans, on the other hand, still remained after therapy in a high proportion of sites initially infected with this microorganism. Subgingival persistence of A. actinomycetemcomitans appeared to be associated with a reduced healing response following debridement. Further studies are needed to clarify why A. actinomycetemcomitans is poorly eliminated following debridement. Also, the long-term clinical significance of the subgingival perseverance of A. actinomycetemcomitans needs to be elucidated.

Actinobacillus↗
PubMed1990

On the inability of root debridement and periodontal surgery to eliminate Actinobacillus actinomycetemcomitans from periodontal pockets.

In a previous study, we observed that root debridement was inefficient in eliminating Actinobacillus actinomycetemcomitans from adult periodontitis lesions. The present report describes the effects on A. actinomycetemcomitans of subsequent treatments of 6 patients that had at least 2 separate sites still harboring A. actinomycetemcomitans 6 months following debridement. 1 site or more in each individual was treated with renewed root debridement and at least 1 other site was treated by surgical excision of the gingival tissue. The results indicated that retreatment with either repeated root debridement or with surgical excision of the gingival tissue was not more effective in eliminating A. actinomycetemcomitans than initial debridement. The possible reasons for this limited therapeutic effect on the subgingival presence of A. actinomycetemcomitans are discussed.

Actinobacillus↗