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Biomedical subjects

C W Douglas

Publications and source records attributed to C W Douglas.

At least 19 recordsLinked to original sources
PubMed2001

Isolation and genotyping of black-pigmented anaerobes from periodontal sites of HIV-positive and non-infected subjects in Thailand.

BACKGROUND, AIMS: The aims of this study were to investigate the prevalence of periodontitis, the prevalence of black-pigmented anaerobes and the genotypes of Porphyromonas gingivalis and Prevotella intermedia present in HIV-infected and control subjects in a heterosexual Thai population. METHOD: 50 AIDS patients and 50 control subjects were included in the study. Their periodontal condition was examined by assessment of bleeding on probing, attachment loss and probing depth, and presence of erythema around 6 teeth (16, 21, 24, 36, 41, 44). Subgingival plaque was collected from the mesiobuccal sites of these teeth and was cultured anaerobically for black-pigmented bacteria. Species were characterised using biochemical profiles and total protein profiles. Genotyping of each isolate was performed using PCR techniques. RESULTS: There was little clinical evidence of HIV-associated periodontitis in the HIV-positive subjects and no difference was found in the prevalence or genotype distribution of black-pigmented anaerobes between HIV-infected and control subjects. CONCLUSIONS: These data suggest lack of severe periodontal destruction due to HIV-infection in Thailand and that these subjects are not colonised by more numerous or characteristic clones of certain putative periodontal pathogens.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Effect of non-surgical periodontal treatment on clinical parameters and the numbers of Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans at adult periodontitis sites.

BACKGROUND, AIMS: The purpose of this study was to relate the numbers of Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans cells to clinical parameters at diseased and healthy periodontal sites before and after non-surgical periodontal therapy using a sensitive quantitative PCR method (Q-PCR). METHOD: The sensitivity of the Q-PCR was less than 10 cells for all three species. Subgingival plaque samples were collected from 541 sites in 50 adult periodontitis subjects pre-treatment, post-treatment and at a follow-up visit (3-6 months post-treatment). Pocket probing depth, attachment loss and bleeding on probing were recorded at each visit and both healthy and diseased sites in each subject were sampled. RESULTS: Quantification revealed that P. gingivalis counts were associated with pocket depth (p=0.006) and attachment loss (p=0.010); however, neither P. intermedia nor A. actinomycetemcomitans was associated with the clinical signs examined. Post-treatment, there was a significant decrease in the numbers of all three species in both the diseased and healthy sites (86-99%) but none were eradicated. Positive associations were found between any two of the three species studied both pre- and post-therapy. By the follow-up visit, there was a significant improvement in the probing depth of deep sites (p=0.001) but in no other clinical parameters. CONCLUSION: This study demonstrates the usefulness of Q-PCR for enumerating putative pathogens in clinical periodontal specimens and that the numbers of the three organisms in all sites decrease with non-surgical periodontal therapy.

Adult↗
PubMed2000

A novel closed-tube quantitative--PCR method for enumerating Porphyromonas gingivitis, Prevotella intermedia and Actinobacillus actinomycetemcomitans.

Enumeration of specific periodontopathogens in subgingival plaque samples has been problematic because of either lack of sensitivity, specificity or the time taken to identify the organisms. These problems can be overcome using PCR, but quantification by this technique is more difficult. We report a simple quantitative PCR method developed for enumerating Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans in clinical samples. The method relies upon inclusion of ethidium bromide in a closed-tube PCR reaction and measurement of resultant amplicons by quantifying the fluorescence generated when UV-light is passed through the walls of the amplification tube. Hence, both PCR and detection are performed in the same tube. The technique was compared with a quantitative competitive PCR and a commercial colorimetric quantitative PCR and proved to be at least as sensitive, specific and reliable for enumeration of the target bacteria. However, its speed and convenience make it particularly useful for large-scale analyses in both clinical laboratories and epidemiological studies.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Oral health problems and significant weight loss among community-dwelling older adults.

BACKGROUND: Studies of hospitalized and institutionalized older adults suggest a relationship between poor oral health and subsequent weight loss. Given the association between weight loss and subsequent mortality and morbidity, we evaluated how oral health problems contributed to significant weight loss over a 1-year period among a representative sample of community-dwelling older adults. METHODS: The study population consisted of 563 adults aged 70 years and older living at home in rural and urban areas in six New England states. Baseline data included information regarding health status, functional status, physical activity, disease diagnoses, lifestyle behaviors, and cognitive and affective status. Dentists performed oral health assessments. One year later, participants were called and asked questions regarding their health and dietary practices and their current weight. RESULTS: Over the 1-year period of follow-up, approximately one third of the sample had lost 4% or more of their previous total body weight; 6% of men and 11% of women lost 10% or more of their previous body weight. Of the subjects, 37% were edentulous; most of these individuals wore full dentures. With gender, income, advanced age, and baseline weight controlled for, edentulousness remained an independent risk factor for significant weight loss (odds ratio 1.63 for 4% weight loss and 2.03 for 10% weight loss). Individuals with increasing numbers of posterior teeth and functional units were at slightly lower risk for weight loss; however, these associations did not reach statistical significance. CONCLUSIONS: Dentate status is an important risk factor for clinically significant weight loss among community-dwelling older adults.

Aged↗
PubMed2000

Enumeration of Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans in subgingival plaque samples by a quantitative-competitive PCR method.

Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans are believed to play an important role in adult periodontitis, but the significance of their relative numbers and progress of the disease is still unclear. Traditional quantitative methods are generally time-consuming and inaccurate. The aim of this study was to develop a sensitive, quantitative PCR technique that would be useful for enumerating P. gingivalis, Pr. intermedia and A. actinomycetemcomitans in subgingival plaque samples from subjects with adult periodontitis. Primers to the following genes were employed: the fimbrial gene (fimA) of P. gingivalis, the 16S rRNA gene of Pr. intermedia and the leukotoxin-A (lktA) gene of A. actinomycetemcomitans. Competitive templates were constructed either by sequence deletion between primer binding sites or by annealing of the primer binding sites to an appropriate DNA core so as to yield products of a different size from that obtained with the target template. Coamplification of target and competitive templates yielded products of expected size and non-specific recognition by the primers was not found. The sensitivity of the designed primers was 100 cells of P. gingivalis, 100 cells of Pr. intermedia and 10 cells of A. actinomycetemcomitans. The three species were found in subgingival plaque samples collected from both healthy and diseased sites by the quantitative-competitive (QC)-PCR method and the technique was more sensitive than cultural methods. For determining the proportions of each of the three periodontopathogens, the total number of bacteria in the samples was enumerated by quantitative-PCR with 16S rRNA universal primers (27f and 342r). The findings indicate that QC-PCR is a useful method for enumerating bacteria in clinical oral specimens and the technique could play a role in the investigation of disease progression.

Actinobacillus Infections↗
PubMed1998

A comparison of intraoral Candida carriage in Sjögren's syndrome patients with healthy xerostomic controls.

OBJECTIVE: Determination of the incidence of Candida carriage in patients with Sjögren's syndrome (SS) and xerostomic controls to assess the influence of immunologic disturbances in SS on carriage. STUDY DESIGN: A total of 16 primary SS patients, 12 secondary SS patients, and 14 xerostomic controls were included in the study. Sampling was performed using an oral rinse method. Aliquots (100 microliters) were spread onto CHROMagar* and incubated for 48 hours. Species identification was confirmed by the germ tube test and API ID32C. Total colony-forming units per milliliter (CFU/ml) were counted and statistical analyses performed by the Kruskal-Wallis test. RESULTS: Candida carriage in primary SS, secondary SS, and xerostomic patients was 81.25%, 66.7%, and 71.4%, respectively. There were no statistically significant differences in total CFU/ml. A wide range of species was isolated in each group. CONCLUSION: The immunologic disturbances seen in SS do not significantly influence the intraoral Candida carriage in patients with a dry mouth.

Adult↗
PubMed1998

Production and sensitivity of bacteriocin-like activity among Porphyromonas gingivalis, Prevotella intermedia and Pr. nigrescens strains isolated from periodontal sites.

The production of and sensitivity to bacteriocin-like activity among 44 strains of black-pigmented anaerobes isolated from periodontal sites were evaluated by both an overlay and an agar diffusion method. The species studied were Porphyromonas gingivalis, Prevotella intermedia and the closely related species Pr. nigrescens. Pr. intermedia strains (90%) produced bacteriocin-like activity against Pr. nigrescens and all Pr. nigrescens were active against Pr. intermedia. Both species showed a high degree of activity against P. gingivalis, whereas only one P. gingivalis strain produced bacteriocin-like activity against either of the other two species. Both Pr. nigrescens and Pr. intermedia showed some activity (40% and 20%, respectively) against other strains of the same species. Such bacteriocin production might be expected to influence the distribution of these black-pigmented species in vivo. Of 224 periodontal sites sampled, only 2.6% yielded mixed cultures of black-pigmented species and of these only one strain, a P. gingivalis isolate, produced bacteriocin-like activity against any of the other strains isolated from these sites. These data support the concept that local production of bacteriocin-like activity in vivo may contribute to the selection of the black-pigmented bacterial profile in subgingival sites.

Adult↗
PubMed1998

Evaluation of the antimicrobial effect of lactoferrin on Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens.

The antimicrobial effect of lactoferrin (apoLf) on the oral, black-pigmented anaerobes Porphyromonas gingivalis, Prevotella intermedia and P. nitrescens has been studied. ApoLf did not kill any of these species but it did inhibit the growth of P. gingivalis, while iron-saturated Lf (FeLf) had no effect. The other two species were unaffected by apoLf. This growth inhibitory effect of apoLf could not be explained on the basis of chelation of inorganic iron, since growth of P. gingivalis occurred in the presence of ethylenediamine di-o-hydroxyphenylacetic acid provided haemin was added. Both apoLf and FeLf reduced haemin uptake by all three species and caused the release of cell-bound haemin in a dose-dependent manner. In addition, haemin reduced the binding of both apoLf and FeLf to P. intermedia and P. nigrescens but stimulated the binding of Lf by P. gingivalis. These data suggest that Lf forms complexes with haemin in solution and competes for the binding of haemin to certain cell receptors, possibly lipopolysaccharides, but this is not sufficient to inhibit growth of the bacteria. P. gingivalis appears to bind Lf-haemin complexes, as well as haemin alone, which may facilitate access of the Lf to the outer and cytoplasmic membranes of P. gingivalis, so disrupting function.

Colony Count, Microbial↗
PubMed1997

Plasma cortisol levels of dogs at a county animal shelter.

Plasmacortisol levels were examined to assess the stress of dogs in a county animal shelter. Groups of dogs confined in the shelter for their 1st, 2nd, or 3rd day had higher cortisol levels than did a group maintained in the shelter for more than 9 days. Dogs in the shelter for an intermediate period (Day 4-9) had intermediate levels of cortisol. The cortisol concentrations of dogs during their first day in the shelter were greater than either those of the same dogs on Day 4/5 in the shelter or those of a group of pet dogs sampled in their own homes. There was no overall effect of 20 min of social interaction with a human (e.g., petting) on the plasma cortisol levels of dogs in the shelter on Day 1-3. However, the gender of the petter did affect cortisol levels. Those dogs interacting with a female had lower cortisol concentrations at the end of the session than did dogs interacting with a male. The results suggest that confinement in a public animal shelter produces a prolonged activation of the hypothalamic-pituitary-adrenal axis. Further, it appears that some subtle aspect of interaction with a human may be capable of moderating this response. Possible implications for the welfare of confined dogs, and for the development of behavior problems in dogs obtained from shelters, are discussed.

Animal Welfare↗
PubMed1997

A numerical taxonomic study of Streptococcus sanguis, S. mitis and similar organisms using conventional tests and pyrolysis mass spectrometry.

Numerical taxonomic methods were applied to the results of pyrolysis mass spectrometry (Py-MS) and conventional test reaction patterns (CTRPs) obtained with 46 strains of oral streptococci identified as representative of six species. Of these: Streptococcus gordonii strains formed a single homogeneous well-differentiated cluster both in the Py-MS and CTRP analyses; S. oralis strains were more diverse, forming 2 CTRP and 3 Py-MS clusters; S. crista, S. parasanguis and S. sanguis formed clear, but diverse and poorly differentiated clusters on the basis of CTRPs, and were poorly differentiated in the Py-MS analysis; and S. mitis strains were clearly diverse in both analyses. Peritrichously fimbriate ('tufted') S. mitis strains formed a tight cluster, well differentiated from the type strain in both Py-MS and CTRP analyses, and may represent a previously unrecognised centre of variation.

Humans↗
PubMed1997

The role of immunoglobulin G and fibrinogen in platelet aggregation by Streptococcus sanguis.

Previous work has shown that the type strain of Streptococcus sanguis, NCTC 7863, induces aggregation of normal platelets by a complement-dependent mechanism. We investigated the roles of IgG and fibrinogen in the aggregation process. Plasma depleted of IgG by passage through protein A-sepharose failed to support platelet aggregation, as did plasma absorbed at 0 degrees C with whole bacteria. However, absorption of plasma with a non-aggregating strain of S. sanguis, SK96, did not remove aggregating activity for NCTC 7863. Supplementing 0 degrees C-absorbed plasma with purified IgG restored the aggregation supporting activity. A monoclonal antibody to the Fc gammaRII receptor inhibited platelet aggregation by the bacteria, indicating a requirement for bacteria-IgG complexes interacting with the Fc receptor in platelet aggregation. There was a lag time to the onset of platelet aggregation of 7-19 min depending upon the platelet donor, but the length of this lag did not correlate with either total IgG concentration recognizing NCTC 7863 in subjects' plasma, or the concentration any of the four IgG subclasses or with IgG avidity levels. Fibrinogen was shown to bind rapidly to the bacterial cell surface. Monoclonal antibody to GPIIb/IIIa, RGDS peptide, and a specific antagonist for the platelet fibrinogen receptor, GPIIb/IIIa, FK633, inhibited platelet aggregation by NCTC 7863, indicating that platelet aggregation is fibrinogen dependent. These data suggest that platelet aggregation by some strains of S. sanguis requires multiple stimuli/agonists, including IgG-Fc receptor interaction, complement and fibrinogen.

Complement System Proteins↗
PubMed1997

The role of platelets in infective endocarditis.

There is growing evidence that platelets play an important role in the development of infective endocarditis (IE). This review focuses on interactions between bacteria and platelets. Many types of microorganism are capable of causing endocarditis. The oral streptococci, particularly Streptococcus sanguis and S. oralis, remain the most common causative bacteria in IE but Staphylococcus aureus is becoming an increasingly important agent. Several species of bacteria and fungi are able to cause platelet aggregation in vitro, and there are indications that this ability is associated with the production of severe disease. Different bacteria appear to utilise different mechanisms of aggregation, and mechanisms for adhesion may be distinct from those responsible for aggregation. At least one commonly studied strain of S. sanguis apparently utilises the host's IgG and complement responses to induce platelet activation. IE may therefore be among the number of diseases in which immunological activation of platelets is thought to be of importance. Other bacterial strains have their own adhesins and agonists. The more virulent bacteria, notably the staphylococci, also possess proteolytic enzymes and may directly activate coagulation pathways, whereas less virulent, opportunistic pathogens, such as some streptococci and Candida albicans, may rely on interactions with host factors for colonisation and proliferation. It is proposed that platelets are involved in formation of the non-bacterial thrombotic vegetation (NBTV) and are necessary for the effective adhesion of bacteria to the NBTV, and that platelets also influence the persistence and clinical outcome of the disease through proliferation of the thrombotic vegetation. It is hypothesised that successful colonisation of the heart valves by a micro-organism depends on effective adhesion of the bacteria or fungi to platelets, in combination with the ability to induce platelet activation and aggregation.

Journal Article↗
PubMed1996

Evidence for the involvement of complement proteins in platelet aggregation by Streptococcus sanguis NCTC 7863.

We investigated the mechanisms of platelet aggregation by the type strain of Streptococcus sanguis (NCTC 7863). This species is one of the major aetiological agents of infective endocarditis. S. sanguis NCTC 7863 caused aggregation of normal human platelets in vitro following a lag period that varied between donors (7-19 min). Platelet aggregation was dependent on one or more plasma constituents and all the necessary factors gradually became bound to the bacterial surface during the lag period. The length of the lag period was determined by the plasma of the donor and not by a feature of their platelets. Platelet aggregation by S. sanguis NCTC 7863 could be inhibited by heating plasma at 56 degrees C, by treating plasma with cobra venom factor, or by incubating with soluble Complement Receptor 1, all of which inhibit or deplete complement. Complement activation required Mg2+, but not Ca2+ ions and the the cleavage fragment, Ba, of factor B was produced, indicating that the alternative pathway was operative. Zymosan- and S. sanguis-induced aggregation showed similarities, including the same variability in lag times among donors, and absorption of plasma with zymosan prevented the plasma from supporting platelet aggregation by S. sanguis, C3, C9 and vitronectin were found to bind to S. sanguis NCTC 7863, but the latter two were present at very low levels on a non-aggregating strain of S. sanguis, SK96. The rate of assembly of the C5b-9 complex on the NCTC 7863 bacterial surface correlated with the lag time. These data suggest a role for the complement pathway in platelet aggregation by the type strain of S. sanguis.

Complement C1↗
PubMed1996

Binding and degradation of lactoferrin by Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens.

The ability of laboratory and clinical strains of Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens to bind and to degrade lactoferrin (Lf) has been assessed. Lf bound readily to whole cells of each species apparently via high-affinity site and one or more low-affinity sites. P. gingivalis showed a lower affinity for Lf than the other two species (P < 0.001). Virtually all strains of P. gingivalis completely degraded Lf under the conditions employed, whereas P. intermedia and P. nigrescens showed only partial degradation. These data suggest that Lf binds to a high-affinity receptor on all these bacteria and, particularly in the case of P. gingivalis, is then degraded by cell-associated proteases. This property may provide protection to the cell against the effects of Lf in periodontal sites and so is a possible virulence factor in disease. There was no association between the ability to degrade Lf and whether the strains had originated from healthy or diseased oral sites.

Humans↗
PubMed1996

Clonality of Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens isolated from periodontally diseased and healthy sites.

Black-pigmented anaerobes have been implicated as major pathogens in the aetiology of adult periodontitis but these organisms are also found in healthy sites. This study aimed to examine the relationship between genotypes of black-pigmented anaerobes and disease status of periodontal sites using restriction endonuclease analysis (REA) and ribotyping. The main black-pigmented species recovered from sites were Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens. Each of the 58 subjects investigated harboured distinct genotypes of these three species. Most subjects appeared to be colonized by a single genotype of P. gingivalis and Pr. intermedia, whereas multiple types of Pr. nigrescens colonized many individuals. Plasmids were only found in a few Pr. nigrescens strains. No association was found between the disease status of sites and any specific or group of genotypes of either species or presence of a plasmid. Since the same genotypes of P. gingivalis, Pr. intermedia and Pr. nigrescens were found at both diseased and non-diseased sites in a subject, adult periodontitis is not explained by the presence of specially virulent clones of these organisms. Their role in periodontitis, therefore, is likely to be opportunistic.

Adult↗
PubMed1995

Prevalence of penicillin resistant bacteria in acute suppurative oral infection.

Pus aspirated from acute suppurative oral infections in 78 patients (age range 13-76 years) yielded a total of 331 bacterial strains consisting of 143 facultative anaerobes (predominantly Streptococcus spp.) and 188 strict anaerobes (predominantly Prevotella spp.). Seventy-five isolates (23%) were resistant to penicillin (MIC > 1 mg/L), 37 (11%) were resistant to ampicillin (MIC > 2 mg/L) and 16 (5%) isolates were resistant to amoxycillin/clavulanic acid (MIC > 2 mg/L). Samples from 43 (55%) of the patients yielded at least one penicillin resistant isolate and within this group 30 samples (73%) contained at least one strain which produced beta-lactamase. A history of antibiotic therapy during the 6 months before enrollment in the study did not influence the isolation of penicillin resistant bacteria. It is concluded that penicillin resistant bacteria are often present in the microflora of acute dental infection.

Acute Disease↗
PubMed1995

Characterisation of black-pigmented anaerobes isolated from diseased and healthy periodontal sites.

Prevotella intermedia has recently been re-defined and a new species, Prevotella nigrescens has been proposed. However, there is little data available on the incidence of these new species in periodontal health or disease. Black-pigmented anaerobes isolated from diseased and healthy subgingival sites were identified by serotyping, SDS-PAGE and physiological tests. In adult periodontitis subjects, 64% of active sites, 35.7% of inactive sites and 38.5% of healthy sites yielded black-pigmented anaerobes. Of these, Porphyromonas gingivalis was found in 11% of active and 5% of healthy sites in diseased patients, Prevotella intermedia in 15.5% of active and 20.5% of healthy sites, Prevotella nigrescens in 37.7% of active and 11.5% of healthy sites and Prevotella denticola in 3% of active and 1% of healthy sites. In healthy subjects, 50% of sites yielded black-pigmented anaerobes. P. gingivalis was not found in healthy subjects but P. intermedia was found in 18% and P. nigrescens in 31% of sites. SDS-PAGE proved to be a useful method for routinely differentiating P. intermedia and P. nigrescens and two sub-types of the latter species were detected on the basis of band pattern. Only one P. nigrescens sub-type was found in any given individual and one type, typified by ATCC 25261, was more commonly found in deep pockets. However, overall both P. nigrescens and P. intermedia as species were just as frequently found at healthy sites as diseased sites. Thus, these species, in contrast to P. gingivalis, appear to be common commensals but they may act as opportunistic pathogens.

Adult↗