Biomedical subjects

D Beighton

Publications and source records attributed to D Beighton.

At least 109 records · Page 6Linked to original sources

PubMed1992

Glycosidase activities in gingival crevicular fluid in subjects with adult periodontitis or gingivitis.

Specific glycosidase activities were determined in samples of gingival crevicular fluid (GCF) collected from eight predetermined sites in two groups, each of 20 adult patients, with either gingivitis or periodontitis. The total activities (as units of enzyme activity per sample) of alpha-L-fucosidase, sialidase, beta-N-acetylglucosaminidase, beta-galactosidase, beta-glucosidase and alpha-glucosidase were significantly greater in the periodontitis group. In contrast, the total beta-mannosidase and hexosaminidase A activities were significantly greater in the gingivitis group, while there was no significant difference in the total alpha-mannosidase activity between the groups. Only the specific activities (as units of enzyme activity per min per microliter of GCF) of beta-mannosidase and hexosaminidase A were significantly different between the groups being greater in the gingivitis group. When used to predict the clinical status of individual periodontal sites, the total enzyme activities had specificity and sensitivity values of 91.9 and 61.3%, respectively. Measurement of glycosidase activities might thus have a role in monitoring the efficacy of periodontal treatment or in predicting future periodontal disease but this will require further investigation.

Adult↗

PubMed1992

Inhibition of human subgingival plaque protease activity by chlorhexidine.

Subgingival plaque samples from three discrete sites in each of eight patients with adult chronic periodontitis were used to determine the ability of 0.001, 0.01, 0.1 and 1.0 mM chlorhexidine to inhibit bacterial proteolytic activity. This activity was measured by monitoring the increase in relative fluorescence (excitation and emission wavelengths of 495 and 525 nm, respectively) accompanying the degradation of fluorescein isothiocyanate (FITC)-labelled bovine serum albumin or FITC-labelled transferrin. Chlorhexidine at concentrations of as low as 0.01 mM inhibited the proteolytic degradation of both substrates by more than 50%. As the growth of dental plaque bacteria is dependent upon the liberation of nutrients (amino acids, peptides and carbohydrates) from host-derived macromolecules, similar effects in vivo might explain the ability of chlorhexidine to inhibit plaque formation at subminimal inhibitory concentrations.

Bacteria↗

PubMed1992

Development of dental plaque on the incisor teeth of monkeys (Macaca fascicularis).

Bacterial plaque which had accumulated for 0.5, 1, 2, 4, 7, 14 and 28 days was cultured from the labial surface of one of the central incisor teeth in 15 monkeys (Macaca fascicularis). Each sampling area was defined by a metal well contained within a custom-made removable acrylic block. The number (log10) of the total colony forming units (c.f.u.) increased significantly from 3.40 to 6.02 between 0.5 and 28 days. Similarly the number of streptococci increased from 2.80 to 4.79 during the same period, although when expressed as a percentage of the total c.f.u., the proportions decreased from 34.9 per cent at 1 day to 6.9 per cent at 7 days and then remained at that level. The number of micro-aerophilic actinomyces increased throughout the period of plaque accumulation and comprised 15.3 per cent of the total c.f.u. at 28 days. Neisseriae were infrequently isolated from 0.5- and 1-day-old plaque and were not recovered at more than 1 per cent of the total c.f.u. during any period of plaque accumulation. The fastest doubling time (median) of the total c.f.u. was 1.9 h (range 1.3-18.5 h). The rapid development of dental plaque after tooth cleaning emphasizes the importance of regular and meticulous oral hygiene to control the accumulation of potentially periodontopathic and cariogenic bacteria.

Analysis of Variance↗

PubMed1992

A numerical taxonomic study of the "Streptococcus milleri" group based upon conventional phenotypic tests and pyrolysis mass spectrometry.

Clinical strains presumptively identified as Streptococcus milleri (60), and blind coded collection strains (21) were characterised in conventional tests and pyrolysis mass spectrometry. Comparison of the clusters found by these two approaches revealed five clearly distinct centres of variation. Three corresponded to the DNA homology groups suggested by Whiley and Hardie (1989) as representing the species S. anginosus, S. intermedius and S. constellatus; a fourth comprised three Lancefield group C beta-haemolytic strains; the fifth may represent a biotype of S. anginosus. The characteristics of the latter group are described.

Cluster Analysis↗

PubMed1992

Inhibition of peptidase and glycosidase activities of Porphyromonas gingivalis, Bacteroides intermedius and Treponema denticola by plant extracts.

Aqueous extracts from 5 plants used widely in Kenya as chewing sticks (mswaki) for the control of oral hygiene were tested for their ability to inhibit extracellular peptidase and glycosidase enzyme activities produced by the periodontopathic bacteria Porphyromonas gingivalis (formerly Bacteroides gingivalis), Bacteroides intermedius and Treponema denticola. The plants studied were Rhus natalensis, Cupressus hisitanica, Sida cordifolia, Olea africana and Euclea divinorum. Protease activities, including glycylprolyl dipeptidase and trypsin-like activities of P. gingivalis, chymotrypsin-like and glycylprolyl dipeptidase activities of B. intermedius and the trypsin-like activity of T. denticola, were particularly affected by extracts from Rhus natalensis and Euclea divinorum. Glycosidase activities were generally less affected with the notable exceptions of the inhibition of beta-mannosidase activity of P. gingivalis by all extracts and the inhibition of neuraminidase activity of T. denticola by Rhus natalensis and Euclea divinorum. Generally, these same proteolytic and glycosidic activities were inhibited by tannic acid and to lesser extents by gallic acid and gallic acid methyl ester. An inhibitory component, present in all extracts, exhibited physical and chemical properties identical to those of tannic acid. The inhibition of these enzyme activities is likely to reduce the virulence of these periodontophathic bacteria and to reduce the rate of dental plaque formation.

Bacteroides↗

PubMed1992

Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus (the Streptococcus milleri group): association with different body sites and clinical infections.

The associations of Streptococcus intermedius, S. constellatus, and S. anginosus (the three species of the S. milleri group) with clinical infections and sites of isolation were investigated by using a simple biochemical scheme to identify a collection of 153 clinical isolates. S. intermedius was associated with abscesses of the brain and liver, while both S. anginosus and S. constellatus were isolated from a wider range of sites and infections. S. anginosus strains predominated in both genitourinary and gastrointestinal sources and exhibited a wider range of phenotypes, particularly in the ability to ferment mannitol and/or raffinose.

Central Nervous System Diseases↗

PubMed1991

Emended descriptions and recognition of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus as distinct species.

Strains currently classified as Streptococcus anginosus include strains previously identified as Streptococcus constellatus (Prevot 1924) Holdeman and Moore 1974, Streptococcus intermedius (Prevot 1925), and "Streptococcus milleri" (Guthof 1956) because these specific epithets were argued to be later synonyms of Streptococcus anginosus (Andrewes and Horder 1906) Smith and Sherman 1938 by Coykendall et al. (Int. J. Syst. Bacteriol. 37:222-228, 1987). However, recent data from DNA-DNA hybridization experiments, whole-cell-derived polypeptide patterns determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and data from phenotypic testing have demonstrated that Streptococcus anginosus strains represent three readily identifiable taxa to which the previously assigned type strains of Streptococcus constellatus (strain NCDO 2226 [= ATCC 27823], Streptococcus intermedius (strain NCDO 2227 [= ATCC 27335], and Streptococcus anginosus (strain NCTC 10713 [= ATCC 33397] have been shown to belong. Therefore, we propose recognition of Streptococcus constellatus (emend.) (type strain NCDO 2226 [= ATCC 27823]), Streptococcus intermedius (emend.) (type strain NCDO 2227 [= ATCC 27335]), and Streptococcus anginosus (emend.) (type strain NCTC 10713 [= ATCC 33397]) as distinct species and propose an emended description of each of these taxa.

Base Composition↗

PubMed1991

Streptococcus crista sp. nov., a viridans streptococcus with tufted fibrils, isolated from the human oral cavity and throat.

We studied strains of an unusual streptococcus that superficially resembles Streptococcus sanguis but has fibrils that are arranged in lateral tufts. These strains were originally isolated from human throats and oral cavities and have been referred to previously as "Streptococcus sanguis I," the "CR group," and the "tufted-fibril group." Until now, insufficient phenotypic data have been available to allow reliable differentiation of these strains from other viridans streptococcal species, particularly the species in the S. sanguis group. Recently, workers have proposed a scheme of phenetic tests that is based on 4-methylumbelliferyl-linked substrates and conventional biochemical tests and allows the tufted-fibril group to be differentiated; these organisms differ from other viridans species in being able to hydrolyze arginine but not esculin and in producing alpha-L-fucosidase but not beta-glucosidase or alkaline phosphatase. These data, together with the results of our DNA-DNA hybridization experiments and the unusual ultrastructure of the tufted-fibril strains as determined by electron microscopy, demonstrate that these organisms represent a new species, for which the name Streptococcus crista is proposed. The DNA base composition is 42.6 to 43.2 mol% G + C. The type strain is strain CR311 (= NCTC 12479).

DNA, Bacterial↗

PubMed1991

A scheme for the identification of viridans streptococci.

A collection of strains representing all the currently recognised species of oral or viridans streptococci (Streptococcus sanguis, S. parasanguis, S. gordonii, S. oralis, S. mitis, S. salivarius, S. vestibularis, S. anginosus, S. constellatus, s. intermedius, S. mutans and S. sobrinus) were tested for the production of a range of glycosidase activities with 4-methylumbelliferyl-linked fluorogenic substrates, and for reactions in a range of conventional fermentation and hydrolytic tests. The resulting biochemical scheme, consisting of 14 tests, enabled the differentiation of all these species and distinguished three biotypes within S. sanguis. The scheme reported here represents an improvement over currently available schemes for the identification of viridans streptococci.

Culture Media↗

PubMed1991

Cloning and expression of protease genes from Treponema denticola in Escherichia coli.

A gene bank of random fragments of chromosomal DNA from Treponema denticola ATCC 33520 was constructed in the bacteriophage vector lambda L47.1. The gene bank was plated on Escherichia coli C600 and screened for the presence of plaques in which enzyme activity was expressed, using overlays of fluorogenic synthetic substrates and a two-step procedure in which immunological screening was followed by enzyme assays of immunopositive lysates. Recombinants expressing trypsin-like, chymotrypsin-like and proline iminopeptidase activities were found. The gene for the trypsin-like activity was subcloned into plasmid pJDC9 and maintained in E. coli.

Aminopeptidases↗

PubMed1991

Effects of chlorhexidine on proteolytic and glycosidic enzyme activities of dental plaque bacteria.

Chlorhexidine was tested for its ability to inhibit a wide range of glycosidic and proteolytic enzyme activities produced by Treponema denticola, Porphyromonas gingivalis, Bacteroides intermedius, Actinobacillus actinomycemcomitans, Capnocytophaga sputigena, Capnocytophaga gingivalis, Capnocytophaga orchracea, Capnocytophaga sp., Actinomyces viscosus, Streptococcus mitior, Streptococcus mutans, Streptococcus sobrinus, Streptococcus mitis, Streptococcus anginosus, Streptococcus oralis and Streptococcus sanguis. The enzymes produced by Capnocytophaga spp. were the most resistant to inhibition by chlorhexidine while the hydrolysis of proteolytic substrates by all the other species was markedly susceptible to inhibition with less than 0.125 mM chlorhexidine inhibiting enzyme activities by greater than or equal to 50%. Glycosidase activities, of all species, were generally more resistant to inhibition, especially neuraminidase activity. Chlorhexidine at less than 0.032 mM inhibited the degradation of bovine serum albumin by suspensions of dental plaque bacteria. These observations support an hypothesis that chlorhexidine exerts a bacteristatic effect in vivo, in part, by reducing the ability of dental plaque bacteria to degrade host-derived proteins and glycoproteins which normally provide essential nutrients for growth.

Acetylglucosaminidase↗

PubMed1991

Salivary levels of mutans streptococci, lactobacilli, yeasts, and root caries prevalence in non-institutionalized elderly dental patients.

Root caries prevalence was recorded for a consecutive sample of dental patients (n = 146), aged over 55 yr and with at least 12 natural teeth. The mean root DFS score of the males (n = 49) was 6.34 +/- 4.55 and for the females (n = 97) 3.76 +/- 3.31 (P less than 0.001). The salivary levels of mutans streptococci, lactobacilli, and yeasts were determined in addition to salivary flow rate and buffering capacity. Subjects with greater than 1 root DFS had significantly higher salivary levels of mutans streptococci, lactobacilli, and yeasts. They also had fewer teeth and more exposed root surfaces. In step-wise multivariate analyses the factors significantly related to the root DFS score were the number of exposed root surfaces, number of teeth, sex and salivary yeast levels (R2 = 0.41). In the multivariate analyses salivary levels of mutans streptococci were not significantly related to any clinical measurement of root caries experience due to the greater strength of association between the root DFS score and salivary levels of yeasts. Subjects prescribed medicines with a reported xerostomic effect had significantly fewer active root lesions than those not prescribed such medicines and salivary levels of all microorganisms studied were significantly elevated in subjects prescribed medications containing sucrose.

Aged↗

PubMed1991

A simple biochemical scheme for the differentiation of Streptococcus mutans and Streptococcus sobrinus.

A collection of wild-type and reference strains of Streptococcus mutans and Streptococcus sobrinus was compared using a set of fermentation and enzymic tests in order to establish a simple scheme for the differentiation of these two species isolated from selective media. Tests for the production of acid from N-acetylglucosamine, arbutin and melibiose, and the presence of alpha-galactosidase and alpha-glucosidase activities were useful in differentiating these species. Strains of Streptococcus mutans unable to ferment melibiose were also frequently unable to ferment other sugars; a consideration of the genetic control and organization of the genes involved in melibiose metabolism indicates that certain of the conventional characterization tests are not measurements of independent biochemical capabilities.

Adolescent↗

PubMed1990

Fluorometric determination of bacterial protease activity using fluorescein isothiocyanate-labeled proteins as substrates.

Intact fluorescein isothiocyanate-labeled proteins have relatively low background fluorescence at excitation and emission wavelengths of 495 and 525 nm, respectively. Degradation of these substrates leads to exposure of covalently linked fluorescein isothiocyanate molecules and to a concomitant increase in relative fluorescence at these wavelengths. The increase in relative fluorescence is proportional to the degree of protein degradation. This phenomenon provides the basis for a sensitive assay for bacterial protease activity. There is no requirement for the removal of undegraded substrate from the assay mixture prior to the measurement of fluorescence. Assays can be performed in 96-well microtiter trays, enabling a large number of samples and their respective controls to be processed simultaneously and repeated determinations of fluorescence values may be made on the same assay.

Bacteroides↗

PubMed1990

Root caries in older people attending a general dental practice in East Sussex.

With increasing numbers of older people retaining their natural dentitions, dentists are becoming increasingly aware of the problem of dental caries occurring on exposed root surfaces--root caries. This study reports the prevalence of root caries in a selected older population, living in the community and attending a general dental practice in Bexhill, East Sussex. A total of 146 non-institutionalised people, aged at least 55 years with at least 12 teeth, were examined. Most of the subjects (88.4%) had evidence of root caries, males and denture wearers having more lesions than females and non-denture wearers, respectively. Active coronal caries was present in only 11.6% of the subjects, whereas active (soft or leathery) root caries lesions were present in 31.5% of the subjects. The teeth and surfaces most commonly affected by root caries were found to be similar to those seen in previous epidemiological surveys. The majority of active root caries lesions were within 1 mm of the gingival margin, while inactive lesions tended to be greater than or equal to 1 mm from the gingival margin. Colour of root caries lesions was not diagnostic of caries activity. A more detailed method of recording root caries lesions is also described.

Aged↗

PubMed1990

Associations between salivary levels of mutans streptococci, lactobacilli, yeasts and black-pigmented Bacteroides spp. and dental variables in elderly dental patients.

Multivariate step-wise regression analyses demonstrated that in a population of 146 elderly dental patients (mean age 69.8 yr) the salivary level of mutans streptococci was unrelated to the root DFS score, unlike the levels of lactobacilli and yeasts. Mutans streptococci were related to the wearing of partial dentures and the number of snacks eaten per day, while salivary lactobacillus levels were also related to the number of snacks eaten per day and to denture wearing, and negatively related to saliva buffering. Salivary yeast levels were also related to the wearing of partial dentures and the number of snacks eaten per day, and negatively related to salivary neuraminidase activity. The R2 values ranged from 0.21 to 0.28. Salivary level of black-pigmented Bacteroides spp. were related to maximum CPITN score, mean bleeding index and salivary trypsin-like activity (R2 was 0.08).

Aged↗

PubMed1990

Protease activity in gingival crevicular fluid from discrete periodontal sites in humans with periodontitis or gingivitis.

Sensitive fluorogenic assays were used to compare the protease activities of fluid collected from eight such sites in each of 21 adult patients with gingivitis and 22 with periodontitis. The degradation of N-carbobenzoxy-gly-gly-arginine-AMC, L-arginine-AMC, glyproline-AMC, L-leucine-AMC, N-alpha-benzoyl-L-arginine-AMC, N-[p-toluenesulphonyl]-gly-pro-arginine-AMC, N-tert-butoxycarbonyl-leu-ser-thr-arginine-AMC, N-tert-butoxycarbonyl-ileu-glut-gly-arginine-AMC and N-tert-butoxycarbonyl-val-leu-lysine-AMC was significantly greater by fluid from the periodontitis group. The specific rates of degradation of L-arginine-AMC, gly-proline-AMC, N-alpha-benzoyl-L-arginine-AMC and N-[p-toluene-sulphonyl]gly-pro-arginine-AMC were significantly greater in that group, indicating that the composition of their gingival crevicular fluid was different from that of the gingivitis group. Discriminant analysis of the substrate hydrolysis data alone correctly identified 77.6% of sites with sensitivity and specificity values of 73.3 and 82.1%, respectively. The predictive value of these assays requires further investigation, but it is possible that they will prove useful for monitoring the success of periodontal treatment.

Adult↗

PubMed1990

Inhibition of protease activities of periodontopathic bacteria by extracts of plants used in Kenya as chewing sticks (mswaki).

Extracts from five plants used as chewing sticks, and tannic acid, gallic acid and methyl ester of gallic acid, were tested for their ability to inhibit proteolytic activities of three strains of Bacteroides gingivalis, three strains of Bacteroides intermedius and two strains of Treponema denticola. Aqueous extract from the plants Rhus natalensis and Euclea divinorum were the most inhibitory of those tested, inhibiting by 50% the proteolytic activity of the test organisms, at concentrations of up to 200 micrograms/ml. Tannic and gallic acids had similar effects at concentrations of less than 10 micrograms/ml, while the methyl ester of gallic acid was less inhibitory. These findings suggest that extracts from plants used as chewing sticks may possess enough inhibitory components to interfere with the virulence and growth of periodontopathic bacteria in vivo, provided they are able to gain access to the subgingival sites such bacteria preferentially inhabit.

Bacteroides↗