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Biomedical subjects

D Beighton

Publications and source records attributed to D Beighton.

At least 19 recordsLinked to original sources
PubMed2006

The potential for sodium hexametaphosphate (SHMP) found in common children drinks to limit acid production in the oral biofilm.

OBJECTIVE: Sodium hexametaphosphate (SHMP) is a widely used industrial preservative commonly found in children's drinks. In this paper we examined the effect of SHMP incorporated into children's drinks on acid production by the oral biofilm by monitoring salivary concentrations of lactic acid. MATERIALS AND METHOD: Twelve healthy adult subjects with an average age 36 years (range 26-54 years) consumed 10 ml from four children's beverages (Coca Cola and three types of Sunny Delight supplemented with SHMP) and a standard solution of sucrose. Saliva was collected at intervals following exposure of the oral biofilm to the drinks and the clearance of carbohydrates and the appearance of lactate was measured using standard enzymatic techniques. RESULTS: All the carbohydrates derived from the drinks were cleared from saliva within 15 min of consumption. Comparison of two drinks [Sunny D Normal and Sunny C] with the same carbohydrate, but different SHMP concentrations suggested that SHMP in these beverages had no significant effect on acid production. CONCLUSIONS: In this clinical study the role of SHMP, incorporated in common beverages, did not inhibit acid production from carbohydrates.

Acids↗
PubMed2006

Microbiological assessment of occlusal brown-spot lesions in primary molars.

Conventional cultural methods were used to compare the plaque flora and the level of infection of the dentine underlying 51 occlusal brown-spot lesions and 21 sound occlusal sites on the primary dentition. Freshly extracted primary molar teeth were used, and occlusal brown-spot lesions and sound occlusal sites were identified using laser fluorescence (LF) and clinical visual methods. A standardized plaque sample was taken from each site, and an LF score was recorded for one discrete site per tooth. The teeth were carefully opened at each predetermined site to determine the clinical status of the underlying dentine, and samples were collected using a sterile bur. The microbiota of the plaque and dentine samples were enumerated and identified. The mean LF scores for the sound sites and brown-spot lesions were 1.2 and 30.5 (p < 0.001), and all the sound sites exhibited hard sound dentine, but 6 out of 51 brown spots exhibited softened dentine. Overall there was no significant (p > 0.1) difference between the level of infection of the dentine of the sound and brown-spot sites, although some sites in the brown-spot lesions yielded high numbers of bacteria. However, the numbers of bacteria as log10(CFU per sample + 1) +/- SE recovered from the plaque above the brown-spot lesions were significantly greater than above the sound sites, i.e. 2.89 +/- 0.24 and 0.89 +/- 0.33, respectively. These data indicate that brown-spot lesions may be more plaque retentive than sound sites and that they are either arrested or arresting lesions, which may require preventive intervention.

Child↗
PubMed2005

Phenotypic and genotypic selection of microbiota surviving under dental restorations.

The effects of sealing infected carious dentine below dental restorations on the phenotypic and genotypic diversity of the surviving microbiota was investigated. It was hypothesized that the microbiota would be subject to nutrient limitation or nutrient simplification, as it would no longer have access to dietary components or salivary secretion for growth. The available nutrients would be limited primarily to serum proteins passing from the pulp through the patent dentinal tubules to the infected dentine. Ten lesions were treated, and infected dentine was sealed below dental restorations for approximately 5 months. Duplicate standardized samples of infected dentine were taken at baseline and after the removal of the restorations. The baseline microbiota were composed primarily of Lactobacillus spp., Streptococcus mutans, Streptococcus parasanguinis, Actinomyces israelii, and Actinomyces gerencseriae. None of these taxa were isolated among the microbiota of the dentine samples taken after 5 months, which consisted of only Actinomyces naeslundii, Streptococcus oralis, Streptococcus intermedius, and Streptococcus mitis. The microbiota of the final sample exhibited a significantly (P < 0.001) increased ability to produce glycosidic enzymes (sialidase, beta-N-acetylglucosaminidase, and beta-galactosidase), which liberate sugars from glycoproteins. The genotypic diversity of S. oralis and A. naeslundii was significantly (P = 0.002 and P = 0.001, respectively) reduced in the final samples. There was significantly (P < 0.001) greater genotypic diversity within these taxa between the pairs of dentine samples taken at baseline than was found in the 5-month samples, indicating that the dentine was more homogenous than it was at baseline. We propose that during the interval between placement of the restorations and their removal, the available nutrient, primarily serum proteins, or the relative simplicity and homogeneity of the nutrient supply significantly affected the surviving microbiota. The surviving microbiota was less complex, based on compositional, phenotypic, and genotypic analyses, than that isolated from carious lesions which were also exposed to salivary secretions and pH perturbations.

Acetylglucosaminidase↗
PubMed2004

Protein expression by Streptococcus mutans during initial stage of biofilm formation.

Cells growing on surfaces in biofilms exhibit properties distinct from those of planktonic cells, such as increased resistance to biocides and antimicrobial agents. In spite of increased interest in biofilms, very little is known about alterations in cell physiology that occur upon attachment of cells to a surface. In this study we have investigated the changes induced in the protein synthesis by contact of Streptococcus mutans with a surface. Log-phase planktonic cells of S. mutans were allowed to adhere to a glass slide for 2 h in the presence of a (14)C-amino acid mixture. Nonadhered cells were washed away, and the adhered cells were removed by sonication. The proteins were extracted from the nonadhered planktonic and the adhered biofilm cells and separated by two-dimensional gel electrophoresis followed by autoradiography and image analysis. Image analysis revealed that the relative rate of synthesis of 25 proteins was enhanced and that of 8 proteins was diminished > or =1.3-fold in the biofilm cells. Proteins of interest were identified by mass spectrometry and computer-assisted protein sequence analysis. Of the 33 proteins associated with the adhesion response, all but 10 were identified by mass spectrometry and peptide mass fingerprinting. The most prominent change in adhered cells was the increase in relative synthesis of enzymes involved in carbohydrate catabolism indicating that a redirection in protein synthesis towards energy generation is an early response to contact with and adhesion to a surface.

Bacterial Adhesion↗
PubMed2004

Dental caries, oral hygiene, and oral clearance in children with craniofacial disorders.

The reason that children with cleft palates tend to have a greater prevalence of tooth decay than normal children is unclear. We hypothesized that children with cleft palates would have increased oral clearance times for foods and, consequently, higher levels of caries and caries-associated micro-organisms than control children. Children aged 6-16 yrs, with (n = 81) or without (n = 61) cleft palates, were studied. Children with cleft palates had DMFT and dmft scores greater (p < 0.01) than those of the control group. The number of caries-associated organisms was greater in the saliva of the cleft palate children (all p < 0.001). The oral hygiene, plaque and gingival index scores were greater (p < 0.0001), oral clearance was longer (p < 0.01), and levels of sucrose and starch-derived saccharides higher (p < 0.01) in the cleft palate group. However, salivary concentrations of organic acids were lower in the children with craniofacial disorders, probably reflecting the altered physiology of the more mature dental biofilm. The longer oral clearance times of foods and the consequent generation of fermentable sugars from starches may contribute to the higher caries prevalence observed in children with cleft palates.

Adolescent↗
PubMed2003

Effect of acid shock on protein expression by biofilm cells of Streptococcus mutans.

Streptococcus mutans is a component of the dental plaque biofilm and a major causal agent of dental caries. Log-phase cells of the organism are known to induce an acid tolerance response (ATR) at sub-lethal pH values ( approximately 5.5) that enhances survival at lower pH values such as those encountered in caries lesions. In this study, we have employed a rod biofilm chemostat system to demonstrate that, while planktonic cells induced a strong ATR at pH 5.5, biofilm cells were inherently more acid resistant than such cells in spite of a negligible induction of an ATR. Since these results suggested that surface growth itself triggered an ATR in biofilm cells, we were interested in comparing the effects of a pH change from 7.5 to 5.5 on protein synthesis by the two cell types. For this, cells were pulse labeled with [(14)C]-amino acids following the pH change to pH 5.5, the proteins extracted and separated by two-dimensional (2D) electrophoresis followed by autoradiography and computer-assisted image analysis. A comparison between the cells incubated at pH 5.5 and the control biofilm cells revealed 23 novel proteins that were absent in the control cells, and 126 proteins with an altered relative rate of synthesis. While the number of changes in protein expression in the biofilm cells was within the same range as for planktonic cells, the magnitude of their change was significantly less in biofilm cells, supporting the observation that acidification of biofilm cells induced a negligible ATR. Mass spectrometry and computer-assisted protein sequence analysis revealed that ATR induction of the planktonic cells resulted in the downregulation of glycolytic enzymes presumably to limit cellular damage by the acidification of the external environment. On the other hand, the glycolytic enzymes in control biofilm cells were significantly less downregulated and key enzymes, such as lactate dehydrogenase were upregulated during pH 5.5 incubation, suggesting that the enhanced acid resistance of biofilm cells is associated with the maintenance of pH homeostasis by H+ extrusion via membrane ATPase and increased lactate efflux.

Acids↗
PubMed2002

Oral yeast carriage in patients with advanced cancer.

The aim of this study was to investigate oral yeast carriage amongst patients with advanced cancer. Oral rinse samples were obtained from 120 subjects. Yeasts were isolated using Sabouraud's dextrose agar and CHROMagar Candida, and were identified using a combination of the API 20 C AUX yeast identification system, species-specific PCR and 26S rDNA gene sequencing. Oral yeast carriage was present in 66% of subjects. The frequency of isolation of individual species was: Candida albicans, 46%; Candida glabrata, 18%; Candida dubliniensis, 5%; others, < 5%. The increasing isolation of non-Candida albicans species is clinically important, since these species are often more resistant to antifungal drugs. Oral yeast carriage was associated with denture wearing (P = 0.006), and low stimulated whole salivary flow rate (P = 0.009). Identification of these risk factors offers new strategies for the prevention of oral candidosis in this group of patients.

Adult↗
PubMed2001

Protein expression by planktonic and biofilm cells of Streptococcus mutans.

Streptococcus mutans, a major causal agent of dental caries, functions in nature as a component of a biofilm on teeth (dental plaque) and yet very little information is available on the physiology of the organism in such surface-associated communities. As a consequence, we undertook to examine the synthesis of proteins by planktonic and biofilm cells growing in a biofilm chemostat at pH 7.5 at a dilution rate of 0.1 h(-1) (mean generation time=7 h). Cells were incubated with (14)C-labelled amino acids, the proteins extracted and separated by two-dimensional electrophoresis followed by autoradiography and computer-assisted image analysis. Of 694 proteins analysed, 57 proteins were enhanced 1.3-fold or greater in biofilm cells compared to planktonic cells with 13 only expressed in sessile cells. Diminished protein expression was observed with 78 proteins, nine of which were not expressed in biofilm cells. The identification of enhanced and diminished proteins by mass spectrometry and computer-assisted protein sequence analysis revealed that, in general, glycolytic enzymes involved in acid formation were repressed in biofilm cells, while biosynthetic processes were enhanced. The results show that biofilm cells possess novel proteins, of as yet unknown function, that are not present in planktonic cells.

Animals↗
PubMed2001

Does social deprivation in 1, 2, 3 and 4-year-old Scottish infants influence the frequency isolation of caries-associated micro-organisms?

OBJECTIVES: The aim of this study was to determine if there are associations between the level of social deprivation/affluence and the frequency isolation of caries-associated micro-organisms (Streptococcus mutans, Streptococcus sobrinus, lactobacilli and yeasts) in a large cohort of infants examined annually from 1 to 4 years of age. METHODS: DEPCAT was used to measure the socio-economic status of all consented infants (n=1099--1392) born in Dundee during a 1 year period (total n=1974). Caries-associated micro-organisms were cultured from saliva when the infants were 1, 2, 3 and 4 years of age. Standardised dental examinations were also carried out annually. Log linear analysis, which controlled for caries, was used to look for associations between DEPCAT and the isolation frequency of caries-associated micro-organisms. RESULTS: When controlling for caries, there was an association between DEPCAT and the isolation frequency of yeasts when the infants were 1 and 2 but not when 3 and 4 years old, whereas lactobacilli were associated only when the infants were 3 and 4 years old. Correlations between S. mutans and social deprivation were usually dependent on the caries status of the infants. CONCLUSIONS: The relationship between social deprivation and the isolation frequencies of caries-associated micro-organisms is complex with lactobacilli developing an association when the infants were 3 and 4 years old in contrast to yeasts which were only associated when the infants were 1 and 2 years old. Streptococcus mutans was associated with social deprivation when the infants were 2 years old and older, but dependent on caries status in the 3 and 4 year olds.

Age Factors↗
PubMed2001

Xerostomia in patients with advanced cancer.

The aim of the study was to investigate the features of xerostomia in patients with advanced cancer. The protocol involved completion of the Memorial Symptom Assessment Scale, and measurement of the unstimulated whole salivary flow rate (UWSFR) and the stimulated whole salivary flow rate (SWSFR). One hundred twenty patients participated in the study. Xerostomia was the fourth most common symptom (78% of patients). It was associated with a poor performance status (P = 0.01). The usual cause of xerostomia was drug treatment. There was an association with the total number of drugs prescribed (P = 0.009): the median number of xerostomic drugs prescribed was 4. Xerostomia was ranked the third most distressing symptom. Its severity was correlated with the severity of oral discomfort, dysgeusia, dysmasesia, dysphagia, dysphonia, and anorexia. The UWSFR was a relatively sensitive, but nonspecific, investigation. In contrast, the SWSFR was a relatively specific, but insensitive, investigation.

Adult↗
PubMed2001

The effect of chlorhexidine acetate/xylitol chewing gum on the plaque and gingival indices of elderly occupants in residential homes.

AIM: A randomised, controlled, double-blind, clinical trial was conducted to investigate the effect of a chlorhexidine acetate/xylitol gum (ACHX) on the plaque and gingival indices of 111 elderly occupants in residential homes. A gum containing xylitol alone (X) and a no gum (N) group was included. Participants' opinions about chewing gum were also investigated. METHODS: Subjects chewed 2 pellets, for 15 min, 2x daily for 12 months. RESULTS: In the ACHX group, the plaque and gingival indices significantly decreased (p<0.001) over the 12 months. In the X group, only the plaque score significantly decreased (p<0.05) and in the N control group, both indices remained high and did not change significantly. The acceptance of both chewing gums was high but more participants in the ACHX group felt that the gum kept their mouth healthy (p<0.05). The effect of the ACHX gum on plaque and gingival indices was significantly greater than for the X gum. CONCLUSION: The long-term use of a chlorhexidine acetate/xylitol chewing gum may therefore support oral hygiene routines for an elderly dependent population.

Aged↗
PubMed2001

Relationship between oral hygiene practices and oral status in dentate elderly people living in residential homes.

OBJECTIVES: To investigate the relationship between the oral hygiene practices of dentate elderly people living in residential homes, their requests for assistance and their oral health status. METHODS: 164 people (81.2+/-7.4 years) participated in an interview and oral examination, and provided a stimulated saliva sample. RESULTS: The mean number of coronal decayed surfaces (CDS) was 2.4+/-5.9, stimulated salivary levels (log(10)cfu/ml) of mutans streptococci, lactobacilli and yeasts were 1.6+/-2.1, 3.0+/-2.2, 2.1+/-1.7, respectively, and 53% had root decayed surfaces (RDS). Plaque (PI) and gingival (GI) Indices were 2.3+/-0.7 and 1.6+/-0.4 and denture debris scores (DDS) were high. 31% of the population cleaned their mouths twice daily without requesting help and they had significantly fewer yeasts, RDS, restorations on root surfaces, lower PI, GI (P<0.005) and DDS (P<0.0001) than the 69% who cleaned less often. 50% of those who cleaned less frequently requested assistance with oral hygiene but only 5% said that their carers supported them. Those residents who requested help had significantly higher levels of yeasts, lactobacilli (P<0.001), retained roots, DDS, RDS (P<0.005), PI and GI (P<0.0001). CONCLUSION: The elderly residents' perceived need for assistance with oral hygiene was related directly to oral hygiene status and to clinical indicators of mucosal and dental diseases.

Aged↗
PubMed2001

Distribution of endo-beta-N-acetylglucosaminidase amongst enterococci.

Enterococci are becoming increasingly important nosocomial pathogens, a fact mainly attributed to their antimicrobial resistance profiles. However, the enzymic activities required for these organisms to proliferate in vivo have received little attention. Enterococcus faecalis has been shown previously to produce an endo-beta-N-acetylglucosaminidase activity which cleaves high mannose-type glycans in glycoproteins between the N-acetylglucosamine residues of the pentasaccharide core. This study investigated the distribution of this endoglycosidase activity amongst the other enterococcal species. Ribonuclease B, a high mannose-type glycoprotein, was used as a substrate and endoglycosidase activity was demonstrated by a combination of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry and high pH anion-exchange chromatography. Endo-beta-N-acetylglucosaminidase activity was present in 10 of the 18 enterococcal species isolated from both human and animal sources, including all E. faecalis strains. The most notable exception was the lack of this activity in all E. faecium isolates tested. All enterococcal species possessing endoglycosidase activity utilised the liberated glycans to support bacterial growth.

Enterococcus↗
PubMed2001

Altered protein expression of Streptococcus oralis cultured at low pH revealed by two-dimensional gel electrophoresis.

Streptococcus oralis is the predominant aciduric nonmutans streptococcus isolated from the human dentition, but the role of this organism in the initiation and progression of dental caries has yet to be established. To identify proteins that are differentially expressed by S. oralis growing under conditions of low pH, soluble cellular proteins extracted from bacteria grown in batch culture at pH 5.2 or 7.0 were analyzed by two-dimensional (2-D) gel electrophoresis. Thirty-nine proteins had altered expression at low pH; these were excised, digested with trypsin using an in-gel protocol, and further analyzed by peptide mass fingerprinting using matrix-assisted laser desorption ionization mass spectrometry. The resulting fingerprints were compared with the genomic database for Streptococcus pneumoniae, an organism that is phylogenetically closely related to S. oralis, and putative functions for the majority of these proteins were determined on the basis of functional homology. Twenty-eight proteins were up-regulated following growth at pH 5.2; these included enzymes of the glycolytic pathway (glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase), the polypeptide chains comprising ATP synthase, and proteins that are considered to play a role in the general stress response of bacteria, including the 60-kDa chaperone, Hsp33, and superoxide dismutase, and three distinct ABC transporters. These data identify, for the first time, gene products that may be important in the survival and proliferation of nonmutans aciduric S. oralis under conditions of low pH that are likely to be encountered by this organism in vivo.

Bacterial Proteins↗
PubMed2001

Mannosidase production by viridans group streptococci.

The production of mannosidase activity by all currently recognized species of human viridans group streptococci was determined using an assay in which bacterial growth was dependent on the degradation of the high-mannose-type glycans of RNase B and subsequent utilization of released mannose. RNase B is an excellent substrate for the demonstration of mannosidase activity since it is a glycoprotein with a single glycosylation site which is occupied by high-mannose-type glycoforms containing five to nine mannose residues. Mannosidase activity was produced only by some members of the mitis group (Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus cristatus, Streptococcus infantis, Streptococcus parasanguinis, and Streptococcus pneumoniae) and Streptococcus intermedius of the anginosus group. None of the other species within the salivarius and mutans groups or Streptococcus peroris and Streptococcus sanguinis produced mannosidase activity. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, it was demonstrated that the Man(5) glycan alone was degraded while Man(6) to Man(9), which contain terminal alpha(1-->2) mannose residues in addition to the alpha(1-->3), alpha(1-->6), and beta(1-->4) residues present in Man(5), remained intact. Investigations on mannosidase production using synthetic (4-methylumbelliferone- or p-nitrophenol-linked) alpha- or beta-mannosides as substrates indicated that there was no correlation between degradation of these substrates and degradation of the Man(5) glycan of RNase B. No species degraded these alpha-linked mannosides, while degradation of the beta-linked synthetic substrates was restricted to strains within the Streptococcus anginosus, S. gordonii, and S. intermedius species. The data generated using a native glycoprotein as the substrate demonstrate that mannosidase production within the viridans group streptococci is more widely distributed than had previously been considered.

Culture Media↗
PubMed2001

The predominant aciduric microflora of root-caries lesions.

The etiology of root caries is not fully understood, and although mutans streptococci, lactobacilli, and A. naeslundii have been implicated in its initiation and progression, this study was designed to determine the potential role of other microbial species and the nature of predominant aciduric microflora in the root caries process. We isolated the predominant aciduric microflora from root-caries lesions (n = 14) and sound root surfaces in subjects with (n = 13) or without (n = 10) root caries, using both a "most probable numbers" method and conventional plating methods. The predominant aciduric bacteria from root lesions were lactobacilli and A. israelii, while from sound root surfaces in subjects with root caries, A. gerencseriae comprised over 60% of aciduric isolates. Mutans streptococci were not among the aciduric isolates. Subjects without root caries harbored fewer bacteria, and S. anginosus (pH 4.8) and S. oralis (pH 5.2) were the predominant aciduric bacteria. The microbial etiology of root caries is more complex than was previously appreciated, and factors underlying the microbial succession occurring during the disease process are not known. Taxa with previously unrecognized aciduric characteristics have been isolated routinely, and the role of these organisms in the root caries process requires further investigation.

Actinomyces↗