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Biomedical subjects

C W Douglas

Publications and source records attributed to C W Douglas.

At least 55 records · Page 3Linked to original sources
PubMed1990

Amylase-binding as a discriminator among oral streptococci.

The ability of 51 strains, belonging to Streptococcus sanguis, 'S. mitior', S. oralis and related groups, to bind salivary amylase was studied. Most strains were grouped according to their DNA-relatedness and then compared using 14 phenotypic tests. S. mitis, 'S. mitior' and three relatively new groups of strains ('CR', 'MGH' and 'Tufted mitior') bound salivary amylase, while strains of S. sanguis and S. oralis did not. The ability of strains to bind amylase or not was remarkably consistent within groups and the test proved to be reproducible, rapid and easy to perform. Combination of the amylase-binding test with 6 other conventional physiological tests allowed the construction of a dichotomous identification key which correctly identified 95% of strains for which genetic data was available. These findings suggest that the ability of organisms to bind salivary amylase could become a key test in identification schemes for certain oral streptococci.

DNA, Bacterial↗
PubMed1990

Platelet aggregation by oral streptococci.

One proposed mechanism in the pathogenesis of infective endocarditis is the direct aggregation of platelets by the bacteria causing the disease. Some, but not all, strains of Streptococcus sanguis have been reported to aggregate platelets but the taxonomy of this and related taxa has changed recently. The ability to aggregate platelets by 24 genetically grouped laboratory stock strains was studied along with 8 recent isolates from cases of endocarditis. Strains belonging to S. sanguis could aggregate platelets, but not S. gordonii, "S. parasanguis", S. mitis, S. oralis or related taxa. Also, preliminary data indicate that certain biotypes of S. sanguis lack the ability to aggregate platelets. Of the recent clinical isolates, only 4 aggregated platelets and each of these showed phenotypes typical of S. sanguis. These data suggest that the ability to aggregate platelets is not essential for an organism to be able to cause endocarditis, although it may be a significant virulence factor.

Humans↗
PubMed1990

Characterization of the alpha-amylase receptor of Streptococcus gordonii NCTC 7868.

The purpose of the work described here was to investigate the mechanisms involved in the binding of salivary alpha-amylase to Streptococcus gordonii NCTC 7868 (Challis). Of six types of alpha-amylase studied, only mammalian forms of the enzyme were found to bind to S. gordonii cells. Salivary alpha-amylase binding was inhibited by treatment of cells with trypsin and pronase, but not with pepsin or sodium periodate. Presence of starch, dextrin, or maltoheptaose partially inhibited binding of the enzyme to S. gordonii. Both mutanolysin extracts of cells and culture supernatants contained alpha-amylase-binding activity, which was partially purified by Sepharose CL-6B and DEAE-ion-exchange chromatography. Western blotting detected four putative receptor bands--65 kDa, 15 kDa, 12.5 kDa, and one with a very high molecular weight; the lower-molecular-weight components may be products of proteolytic degradation of the high-molecular-weight material, but their true relationship has yet to be determined. Pre-treatment of salivary alpha-amylase with these putative receptors partially inhibited subsequent binding of the enzyme to S. gordonii cells. When bound to cells, only 19% of the salivary alpha-amylase activity was detectable, suggesting that alpha-amylase binds to the receptor at or near the active site of the enzyme.

Chromatography, Affinity↗
PubMed1989

The use of various handwashing agents to decontaminate gloved hands.

It has been suggested that gloved hands could be washed between patient treatments in the dental surgery and gloves re-used, provided they are undamaged. A series of experiments are described, which evaluate the effectiveness of four handwashing agents at removing defined bacterial inoculae from two types of latex rubber glove, a dedicated dental procedure glove (Regent Biogel D) which has a rough surface and a smooth-surfaced examination glove (Microtouch). The four agents tested were povidone iodine (Betadine), chlorhexidine (Hibiscrub), 60% iso-propyl alcohol, and a detergent triclosan preparation (Kleenex washcream). The Biogel D gloves required slightly shorter washing times to eradicate organisms than the Microtouch gloves. It was found that washing with water alone reduced the organisms on gloves by 300-1000-fold, but a minimum washing time of 20 seconds with povidone iodine or chlorhexidine was required to eradicate all the organisms inoculated, except bacterial spores, from both glove surfaces. Povidone-iodine and chlorhexidine were more effective washing agents than iso-propyl alcohol and triclosan soap.

1-Propanol↗
PubMed1989

Quantitation of lactoferrin in odontogenic cyst fluids.

A competitive enzyme linked immunosorbent assay (ELISA) method was used to measure the concentration of lactoferrin in fluids from 36 odontogenic keratocysts, 15 dentigerous cysts, and 30 radicular/residual cysts. Keratocyst fluids contained significantly higher concentrations of lactoferrin than fluids from the other two types of cyst (p less than 0.001); but the range of values obtained within each group was large. Although lactoferrin represents a larger proportion of the total protein in keratocyst fluids than in dentigerous or radicular cyst fluids, lactoferrin concentration is not an absolute diagnostic marker for keratocysts. Lactoferrin concentration correlated strongly with the numbers of neutrophils present in keratocyst fluids (p less than 0.001), less so for dentigerous cyst fluids (p less than 0.05, and not at all in the case of radicular cyst fluids. It is suggested that neutrophils are the source of lactoferrin in the three categories of cyst studied but that the relatively impermeable nature of the keratocyst lining probably accounts for the particularly high concentrations of lactoferrin found in their fluids. Given that most keratocysts were asymptomatic, acute inflammation itself does not explain the reason for the high numbers of neutrophils in many of the fluids.

Dentigerous Cyst↗
PubMed1988

Clinical indicators of radiographically detectable dental diseases in the adult patient.

A comprehensive analysis of the relationship between clinical observations in dental patients without symptoms and oral disease as detected by full-mouth and panoramic dental radiographs in a large population of patients has never been reported. Knowledge of these relationships is necessary in the design of a diagnostic decision process (clinical algorithm) that can predict which patients require dental radiographs for the diagnosis of dental caries or periodontal disease to be confirmed or refined. An accurate clinical algorithm could reduce the number of radiographs that are taken of certain routinely seen dental patients without symptoms, thus reducing unnecessary exposure x-radiation as well as potentially reducing health care costs for these patients. A sample of 602 adult men on whom a complete series of panoramic, posterior bitewing, and periapical dental radiographs and an independent oral examination were performed provided the opportunity to evaluate the relationship between clinically observed oral disease indicators and independent radiographic evidence of dental caries and periodontal disease. The analysis suggests that combinations of several clinical indicators can predict with some success which patients without symptoms will benefit most from oral radiographs. The presence of several carious lesions on oral examination was the best predictor of radiographic detection of dental caries. Clinical indicators tht appear to predict radiographic evidence of periodontal disease are clinical measures of pocket depth, mobility, and the patient's denture status. An important finding is that because of the high prevalence of gingivitis and plaque, these indicators were not related to radiographic evidence of periodontal disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Managed health care.

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Delivery of Health Care↗
PubMed1987

Evidence for the presence of lactoferrin in odontogenic keratocyst fluids.

Investigations into the possibility that X (an antigen consistently present in aspirated odontogenic keratocysts, but not in most fluids from other cyst types), represented a keratinocyte component failed to identify the antigen as a keratin, involucrin, or one of the blood group substances. Antigen X was detected in human mixed and parotid saliva and in colostrum, as well as in a commercially obtained preparation of colostral IgA. The antigen was similar biochemically to both secretory component and lactoferrin but proved to be identical antigenically with lactoferrin. The origin of lactoferrin in keratocyst fluids remains uncertain, though the lining epithelium seems a more likely source than does the very variable, and often negligible, inflammatory infiltrate found in these lesions.

Antigens↗
PubMed1986

Controlling drug release from acrylic polymers: in vitro studies with potential oral inserts.

The use of a drug modified polymer system which can release drugs such as hydrocortisone sodium succinate and chlorhexidine acetate has been explored. By partially coating the drug loaded acrylic, such that it acts as a core with an impermeable membrane covering most of the surface, the rapid releases of the drug can be prevented and near zero-order rates of release achieved. For chlorhexidine acetate the release time was extended from around 20 d to 80 d with at least 60% of the drug being released. A similar potential for the controlled release of hydrocortisone sodium succinate is described and represents an important stage in the development of an intra-oral insert for drug delivery.

Acrylates↗
PubMed1986

Recognition of protein apparently specific to odontogenic keratocyst fluids.

Separate antisera were raised against keratocyst, dentigerous cyst, and radicular cyst fluids and used to analyse a range of fluids from cysts of known type. Samples were subjected to crossed immunoelectrophoresis into homologous antiserum through an intermediate gel containing antibody to whole human serum to screen out serum derived components. A major antigen, designated X, which seems to be of epithelial origin but is not a keratin, was identified in keratocyst fluids. X resolves as two bands on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) with molecular weights of 81 K and 89 K and its major antigenic epitope is associated with disulphide bonds. Of the cysts studied to date, antigen X has been found consistently and exclusively in fluids from keratocysts; its presence and detection is independent of total soluble protein concentration and thus offers real potential as a reliable marker for preoperative diagnosis.

Antigens↗
PubMed1986

Identifying non-capsulate strains of Streptococcus pneumoniae isolated from eyes.

Over six months 10 biochemically and physiologically atypical strains of Streptococcus pneumoniae were isolated from eye swabs. Conventional methodology showed that these strains possessed characteristics of both S pneumoniae and other alpha haemolytic streptococci. The use of sodium dodecyl sulphate - polyacrylamide gel electrophoresis (SDS-PAGE) enabled us to characterise these strains as S pneumoniae. Loss of the capsule seemed to be associated with atypical biochemical properties.

Agglutination↗
PubMed1986

Sylvatic trichinosis in Ontario, Canada.

Samples of muscle from 4,773 specimens of 18 species of wild mammals from Ontario were examined for Trichinella. One of 12 mink (Mustela vison), 83 of 1,821 fisher (Martes pennanti) and 68 of 1,980 marten (Martes americana) had T. spiralis. Prevalences of infections by Trichinella were determined for fisher and marten from the Algonquin region, over a 10-yr period. Prevalences ranged from 0.9-9.2% in fisher and 1.3-8.7% in marten indicating that the parasite is well-established in the region. Prevalences of Trichinella increased with age of both fisher and marten. Intensities determined for the 1981-1982 sample ranged from 0.4-15.8 larvae/g for fisher and 22.4-159.7 larvae/g for marten. Higher intensities were not correlated with older hosts. Fisher and marten appeared to be the key hosts maintaining Trichinella in the Algonquin region, but transmission dynamics were unclear. Transmission may include an unidentified small rodent or other host and natural carrion-feeding.

Animal Population Groups↗
PubMed1984

The adsorption of human salivary components to strains of the bacterium Streptococcus mutans.

Using strains of Streptococcus mutans suspended in human saliva, the salivary proteins capable of binding to the surface of the bacteria were identified by immunological and electrophoretic techniques. Six binding components were recognized: IgA, lysozyme, some high molecular weight material (greater than 400,000), probably a glycoprotein, a low molecular weight component (11-13,000), a 150,000 mol. wt protein, and one major component, mol. wt 20-25,000 which did not resolve fully on SDS-polyacrylamide electrophoresis. All these salivary components could be desorbed from the bacteria with 1 M NaCl, and subsequent extraction of the same cells with 6 M guanidine-HCl did not release any more salivary material. The significance of the binding of these salivary components is unknown but some may modify the behaviour of the organisms in vivo.

Adsorption↗