Biomedical subjects

S Renvert

Publications and source records attributed to S Renvert.

4 recordsLinked to original sources

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↗