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Biomedical subjects

T W MacFarlane

Publications and source records attributed to T W MacFarlane.

At least 19 recordsLinked to original sources
PubMed1995

Microbiological assessment of denture hygiene among patients in longstay and daycare community places.

A simple, inexpensive microbiological assay for objective measurement of denture hygiene has been devised. Small individual filter paper discs were applied to the fitting surface of dentures for 20 seconds, eluted in phosphate buffered saline and bacterial counts on blood agar plates performed on the eluate. There was a strong positive correlation between denture cleanliness (graded on a scale of 0 to 4) and both total anaerobic count (r = 0.829; P < 0.001) and total aerobic count (r = 0.786; P < 0.001) following logarithmic transformation. Yeasts in the eluted disc specimens could be used as an aid to diagnose oral candidiasis. The method provided an objective measure of denture hygiene among elderly patients in longstay hospitals and daycare community places. It may be applicable to audit studies following implementation of new oral health care policies.

Adult↗
PubMed1994

An in vitro investigation of the cariogenic potential of oral streptococci.

Whilst the importance of the mutans streptococci in the aetiology of dental caries is clear, a number of studies have described caries development in their absence. This investigation aimed to assess the cariogenic potential of Streptococcus gordonii, Strep. sanguis, Strep. vestibularis and Enterococcus faecalis in comparison with Strep. mutans and Strep. sobrinus, using a recently described in vitro model. In the presence of a 146 mM sucrose solution and powdered hydroxyapatite, each species was incubated for 5 h, after which acid anion production, calcium release and change in pH were measured. It was possible to assign each species to one of three groups, with E. faecalis, Strep. gordonii, Strep. sanguis exhibiting low, Strep. vestibularis intermediate, and Strep. mutans and Strep. sobrinus high in vitro cariogenic potential. This assay could be used as a screening test to assess the potential cariogenicity of a range of bacterial species.

Acetates↗
PubMed1994

Anti-Candida activity of murine bronchoalveolar lavage fluid.

Respiratory secretions provide an efficient method for protecting the large surface area of the lower respiratory tract. To determine whether lung secretions contribute to antifungal defences, murine bronchoalveolar lavage fluid (BLF) was tested for anti-candidal activity against 49 oral and vaginal isolates belonging to six different Candida species. The yeasts were incubated in unconcentrated, cell-free lavage fluid from Sprague-Dawley rats and then cultured quantitatively to measure residual viability. Experiments with C. albicans indicated that sensitivity to BLF increased in a time- and dose-dependent manner. This activity was heat-stable (56 degrees C) and consistent, irrespective of whether the BLF was derived from rats inoculated (orally) with candida or the uninoculated controls. Of the Candida spp. examined, C. albicans was the most susceptible followed by C. parapsilosis and C. tropicalis, whereas C. krusei, C. guilliermondii and C. glabrata were highly resistant. However, there were differences in susceptibility to BLF among different isolates within a given species. These results indicate that a heat-stable, soluble factor(s) in murine lavage fluid may suppress candidal colonisation of the lower respiratory tract and contribute to the defence mechanisms of the lungs.

Animals↗
PubMed1994

The effect of nebulised pentamidine on the concentration of intra-oral Candida albicans in HIV-infected patients.

This prospective study investigated whether oral candidal carriage in HIV-infected patients was altered by pentamidine therapy. Repeated oral rinses were taken from 56 HIV-positive patients over a 2-year period. Oral candidal carriage was investigated in two groups of patients, one receiving prophylactic pentamidine therapy and the other not receiving regular prophylaxis. Patients receiving pentamidine had lower concentrations of Candida albicans intra-orally than patients who did not receive it. Furthermore, patients who received pentamidine at one stage of the study, but not another, also had lower concentrations of C. albicans intra-orally when receiving pentamidine. These findings indicate that pentamidine is useful as a local agent for prophylaxis against intra-oral candidosis in HIV-infected patients.

Administration, Inhalation↗
PubMed1994

The in vitro proteolytic and saccharolytic activity of Candida species cultured in human saliva.

The proteolytic and saccharolytic activity of 4 Candida species was investigated in batch cultures of pooled, human mixed saliva supplemented with glucose. All the Candida species investigated (Candida albicans, Candida tropicalis, Candida glabrata and Candida krusei) demonstrated a marked growth in saliva with a concomitant reduction in pH from about 7.5 to 3.3, within 72 h. Isotachophoretic analysis of the culture supernatant revealed the presence of a variety of acid anions of which pyruvate and acetate were the most abundant. Proteolysis of salivary components, evaluated by a biochemical assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was exhibited by all 4 Candida species, although there was inter-species variation. Despite the similarity in growth rates, C. tropicalis and C. krusei demonstrated greater proteolytic activity than C. albicans and C. glabrata. Neither candidal growth nor proteolysis was observed in glucose-free control saliva samples. In contrast, the degree of saccharolytic and proteolytic activity of a single isolate of C. albicans in glucose-supplemented parotid saliva appeared to be relatively weak compared with mixed saliva. As the oral cavity provides ideal low pH niches periodically supplemented with dietary carbohydrates, the acidic proteinases of Candida species may play a role in the pathogenesis of oral candidiasis.

Analysis of Variance↗
PubMed1994

The effect of indigenous bacterial populations on buccal epithelial cells on subsequent microbial adhesion in vitro.

Despite the numerous investigations on the adhesion of microorganisms to buccal epithelial cells, it is difficult to correlate different results, as disparate adherence values have been reported for a given organism. As one reason for this disparity may be the indigenous or natural bacterial populations on human buccal epithelial cells, the effect of the latter on subsequent microbial adherence in vitro was examined. There was a highly significant correlation between the degree of natural bacterial colonization on pooled buccal epithelial cells from 8 healthy donors and the adhesion of a single isolate each of Streptococcus mitis, Escherichia coli and Actinomyces naeslundii. However, no such relationship could be established for Candida albicans, Streptococcus milleri and another isolate of Streptococcus mitis. As in previous studies, variation in adherence values was found, both between samples from different donors, and from the same donor over time, but to a far lesser degree in pooled samples from different donors. These results imply that natural bacterial populations on buccal epithelial cells may affect the adhesion values derived from laboratory experimentation, and hence such data should be interpreted with caution.

Actinomyces↗
PubMed1994

The effect of exposure to chlorhexidine gluconate in vitro and in vivo on in vitro adhesion of Candida albicans to buccal epithelial cells from diabetic and non-diabetic subjects.

The effect of 0.2% chlorhexidine gluconate on in vitro adhesion of Candida albicans to buccal epithelial cells (BEC) was studied in 12 healthy subjects and 12 patients with diabetes mellitus. Exposure of BEC for one minute with 0.2% chlorhexidine gluconate in vitro, or by rinsing the mouth in vivo, resulted in a significant reduction in candidal adhesion to BEC in both diabetic and non-diabetic subjects and between both groups. In addition to the known fungicidal effect of chlorhexidine, it also reduces Candida albicans adhesion to oral mucosal cells, a factor of importance in the establishment of candidal infection.

Adult↗
PubMed1993

Salivary protein interactions with oral bacteria: an electrophoretic study.

The relatively low levels of human salivary proteins in whole saliva as compared to the ductal secretions may be related to their interaction with oral bacteria. These interactions are thought to play an important role in the microbial colonisation of the mouth, and salivary proteins adsorbed to oral surfaces have been implicated in adherence. In this study we attempted to investigate the prevalence of interactive strains by screening a range of oral bacteria. Parotid saliva was incubated with bacterial suspensions and consequent alterations to the salivary protein profile determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A number of salivary components were found to be preferentially removed, particularly by those species known to be primary colonizers of clean tooth surfaces.

Animals↗
PubMed1993

The in vitro lysozyme susceptibility of Candida albicans cultured in carbohydrate-supplemented media.

The in vitro lysozyme susceptibility of three oral isolates of Candida albicans cultured in carbohydrate-supplemented media was studied. Lysozyme was shown to have a dose- and time-dependent killing effect on C. albicans isolates. Fungicidal activity persisted to varying degrees when yeast isolates were cultured in a variety of carbohydrates (glucose, galactose, sucrose, maltose, xylitol and lactose) before exposure to 20 micrograms/ml lysozyme. Sucrose and galactose grown yeasts exhibited increased resistance to lysozyme compared with (in decreasing order) those grown in glucose, maltose, xylitol or lactose. Further, the C. albicans isolates tested demonstrated strain variations in their susceptibility to lysozyme. These results suggest that dietary carbohydrate may play a role in modulating the yeast cell populations in the oral cavity by altering the fungal susceptibility to salivary lysozyme.

Analysis of Variance↗
PubMed1992

Assessment of the cariogenic potential of Streptococcus mutans strains and its relationship to in vivo caries experience.

Strains of Streptococcus mutans isolated from the plaque of 6 subjects were studied using an in vitro model to determine whether differences in their cariogenic potential could be detected, and if so, whether the results correlated with the caries experience of the individuals. Each strain was incubated with a bovine enamel slab and 5% (w/v) sucrose for 24-h periods. The acidogenic potential was assessed by pH measurement and analysis of acid anion production. Microradiographic and microdensitometric assessment of the enamel, together with measurement of the change in calcium concentration of the reaction mixture were used to determine the demineralizing potential of each strain. Significant differences in cariogenic potential were found between some of the strains tested, and correlations were found between 3 of the test parameters and the decayed-missing-filled-surface score of the individuals. The results suggest that the caries experience of individuals may be related, to some extent, to the cariogenic potential of their S. mutans strains.

Acetates↗
PubMed1991

Prediction of caries increment in Scottish adolescents.

Salivary, clinical, and microbiological factors were compared with subsequent 2-yr caries increment in a group of 372 Scottish adolescents. The caries increment was significantly correlated with previous caries experience, salivary buffering capacity and counts of lactobacilli, mutans streptococci and candida. Veillonella levels and salivary flow rate were not correlated with caries increment. Significant improvements in the predictions were obtained when the results of more than one test were included using stepwise regression analysis. On an individual basis, using stepwise discriminant analysis, the caries increment group (low, medium, or high) was identified correctly in 49% of all subjects, but this was reduced to 45% if previous caries experience was excluded from the analysis.

Adolescent↗
PubMed1991

Oral candidosis in the elderly in long term hospital care.

A total of 137 patients in long term hospital care were interviewed and examined to determine the prevalence, nature and most important causes of oral candidosis in the hospitalized elderly. Oral candidal infection as determined by the imprint culture technique was present in 47% of patients with a further 31% being carriers of Candida. The prevalence of chronic atrophic candidosis in denture wearers was 38%, while 26% of all patients had angular cheilitis, 67% of which had an infective etiology. Microbiologic examination strongly indicated the upper denture as the major source of infection in those with dentures despite the existence of a ward policy which should have encouraged good oral and denture hygiene.

Aged↗
PubMed1991

Chronic hyperplastic candidosis and secretor status.

A prospective study was undertaken of 22 patients with chronic hyperplastic candidosis and 50 age and sex matched individuals with no evidence of oral mucosal disease. Specifically the relationship between the inherited ability to secrete blood group antigens in saliva and chronic hyperplastic candidosis was investigated. The proportion of non-secretors of blood group antigens was significantly higher in patients with chronic hyperplastic candidosis (68%) compared to the control subjects (38%). The inability to secrete blood group antigens in saliva may therefore be a risk factor in the development of, or persistence of chronic hyperplastic candidosis.

ABO Blood-Group System↗
PubMed1991

Mixed salivary glucose levels and candidal carriage in patients with diabetes mellitus.

The glucose concentration in unstimulated mixed saliva and serum was assayed and correlated with oral candidal colonization in 41 diabetics and 34 healthy control subjects. In diabetic patients, salivary glucose concentration was significantly higher than in the controls and was directly related to blood glucose concentration. Although the difference in the frequency and quantity of oral candidal isolation failed to reach significance between the two groups, diabetic patients who carried Candida intraorally had significantly higher salivary glucose concentrations than those in whom Candida could not be isolated.

Adult↗
PubMed1991

Comparison of the plaque microflora from natural and appliance-borne enamel surfaces.

Human enamel sections and slabs, mounted on a mandibular removable appliance, were worn by 5 adult subjects for a 1-week period. Plaque was allowed to accumulate on the in situ test sites and on the adjacent natural dentition. At the end of the experimental period, the plaque microflora associated with (1) the enamel sections, (2) the enamel slabs, and (3) the acrylic base of the appliance test site was compared with that obtained from lingual and interproximal areas of the lower molar teeth. In addition, the acid anion and pH profiles of plaque obtained from both the exogenous and natural tooth surfaces were also determined. Although some quantitative differences were found between the proportions of isolates obtained from the different enamel surfaces, qualitatively the microflora was very similar, and no significant differences were found in the plaque lactate/acetate ratios or pH measurements following a sucrose mouthrinse. Thus, human tooth specimens mounted on the intra-oral device produced a plaque ecosystem similar to that present on the adjacent natural dentition, suggesting that the model is suitable for studies on early plaque development and the microbiology of enamel demineralization.

Acrylic Resins↗
PubMed1990

Bacteraemia following incision and drainage of dento-alveolar abscesses.

Twenty-five patients undergoing routine incision and drainage of dento-alveolar abscesses were screened for bacteraemia during the procedure. In 13 patients, the abscesses were aspirated with a needle prior to incision and drainage, while needle aspiration was omitted in the remaining 12. A blood sample was taken from all individuals immediately before the surgical procedures and at one-minute intervals for a period of 5 minutes after surgery. Needle aspiration of pus resulted in a significant reduction (P less than 0.05) in the bacteraemic episodes (0 out of 13) during subsequent surgery as compared with incision and drainage, without aspiration (3 out of 12). Bacteraemia appeared to be transient, although in one case it was detected at 5 minutes. It is concluded that bacteraemic episodes occur during incision and drainage of dento-alveolar abscesses and this may be reduced by aspiration of the abscess contents prior to incision and drainage. In addition, the aspirates could serve as excellent microbiological samples, uncontaminated with salivary flora. The need for antibiotic cover in at risk patients, however, needs to be established by further studies.

Bacteria↗
PubMed1990

The microbiology of periapical granulomas.

Of the 16 periapical granulomas studied, 14 (88%) yielded a positive growth when homogenized and cultured. The concentration of colony-forming units per milliliter of the suspension ranged from 10(1.3) to 10(4.0) (mean 10(2.2)). A total of 47 isolates comprising 26 (55%) facultative anaerobes and 21 (45%) strict anaerobes were obtained. The organisms most commonly cultured were Veillonella species (15%), Streptococcus milleri (11%), Streptococcus sanguis (11%), Actinomyces naeslundii (11%), Propionibacterium acnes (11%), and Bacteroides species (10%). Most of the organisms (96%) were sensitive to either amoxicillin, clindamycin, or tetracycline, whereas only 45% were sensitive to metronidazole.

Adolescent↗