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Biomedical subjects

T W MacFarlane

Publications and source records attributed to T W MacFarlane.

At least 37 records · Page 2Linked to original sources
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

Phagocytosis of bacterial strains isolated from acute dentoalveolar abscess.

The phagocytosis by human polymorphonuclear leucocytes of 37 bacterial strains identified as Streptococcus milleri (10 strains), strictly anaerobic gram-positive cocci (10) Prevotella intermedia (6), Pr. oralis (5) and Fusobacterium nucleatum (6) was investigated in vitro. The ingestion of S. milleri and strictly anaerobic gram-positive cocci was significantly greater (p < 0.001) than that of strains of Prevotella spp. and F. nucleatum. The degree of uptake of capsulate and non-capsulate strains did not differ.

Acute Disease↗
PubMed1993

Local and systemic antibody response to putative periodontopathogens in patients with chronic periodontitis: correlation with clinical indices.

Specific immunoglobulin G (IgG), IgA and IgM antibody titres to Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were measured by enzyme-linked immunosorbent assay in serum and gingival crevicular fluid at 5 sites in each of 20 chronic periodontitis patients. Specific serum antibody titres correlated with mean gingival crevicular fluid titres. The 3 immunoglobulin subclass responses (IgA, IgG and IgM) to P. gingivalis correlated. A comparison of sites with probing depth < 4 mm and > or = 4 mm showed that the latter group had significantly lower gingival crevicular fluid IgG titres to P. gingivalis. Sites with a gingival index of 3 had significantly lower gingival crevicular fluid IgG titres to this organism than those with a gingival index of less than 3. These findings support the concept that the humoral immune response is protective, as chronic periodontitis patients with greater pocket depths and more gingival inflammation had paradoxically lower antibody titres to suspected periodontopathogens.

Adult↗
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↗
PubMed1993

The in vitro lysozyme susceptibility of Candida species cultured in sucrose supplemented media.

The in vitro sensitivity to lysozyme of twelve isolates of Candida (three isolates each of C. albicans, C. tropicalis, C. glabrata and C. krusei) pre-incubated in sucrose supplemented media, was determined by a growth inhibition assay. In general, C. albicans and C. tropicalis exhibited increased susceptibility to lysozyme as the sucrose concentration in the growth medium was reduced. Candida krusei demonstrated the reverse effect and C. glabrata isolates showed different trends. Although generally the Candida species examined were susceptible to lysozyme in the decreasing order of C. glabrata, C. albicans, C. tropicalis and C. krusei, differences in susceptibility were noted among different isolates within a given species. These results imply that salivary lysozyme and dietary carbohydrates may exert selective pressure on oral colonization by Candida species.

Candida↗
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↗
PubMed1990

A microbiological and clinical review of the acute dentoalveolar abscess.

Early microbiological studies of acute suppurative dental infection implicated streptococci or staphylococci as the causative microorganisms but recent studies suggest that the microbial flora of acute dentoalveolar abscess is usually polymicrobial, predominantly involving CO2-dependent streptococci, strictly anaerobic Gram-positive cocci and strictly anaerobic Gram-negative bacilli. These differences are probably due to poor sampling techniques and inadequate culture methods used in the early investigations. It is now accepted that specimens should be obtained by aspiration to avoid contamination and processed promptly using strict anaerobic culture. Traditionally the bacterial strains isolated have been regarded as members of the normal oral commensal microflora but it is becoming increasingly apparent from experimental infections that they have pathogenic properties. Although the vast majority of isolates have been found to be sensitive to a variety of antimicrobial agents there would not appear to be a uniformly effective drug. At the present time a penicillin, such as amoxycillin, would probably be the first choice antimicrobial agent with the addition of metronidazole if clinical improvement does not occur.

Acute Disease↗
PubMed1990

The relationship between colonisation, secretor status and in-vitro adhesion of Candida albicans to buccal epithelial cells from diabetics.

This study investigated whether oral candida infection in diabetics and adhesion of Candida albicans to buccal epithelial cells in vitro were related. Buccal cells from 50 patients with diabetes mellitus showed a significant increase in adhesion of C. albicans strain CDS 88 compared with those collected from 50 non-diabetic controls matched for age, sex and denture status. Oral candida carriage, candida infection and secretor status were also investigated in both groups. The frequency of carriage was increased, but not significantly, and there was a significantly higher incidence of candida infection in diabetic patients compared with controls. Diabetic patients who were non-secretors had a significantly increased frequency of oral candida carriage.

Candida albicans↗
PubMed1990

An in vitro method to study the adherence of bacteria to saliva-treated tooth enamel sections.

An in vitro bacterial adherence assay which employed human tooth enamel sections precoated with saliva and an epifluorescent staining technique with acridine orange was developed. The assay was used to study the adherence properties of fresh and type strains of the following oral bacterial species: Bacteroides gingivalis, Bacteroides intermedius, Capnocytophaga species, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Peptostreptococcus species, Veillonella species, Actinomyces israelii, Streptococcus salivarius and Streptococcus sanguis. Approximately half of the bacteria tested adhered well to enamel, including the fresh isolates of B. gingivalis, B. intermedius, Veillonella species and S. sanguis. Adherence did not correlate in all cases with the known distribution of these species in vivo. Three-quarters of the fresh strains adhered better than the type strains of the same species. The assay method is an alternative to the widely used hydroxyapatite bead assay.

Bacterial Adhesion↗
PubMed1990

Caries prevalence and microbiological and salivary caries activity tests in Scottish adolescents.

Salivary and microbiological caries activity tests were investigated on three occasions in a group of 372 Scottish adolescents. Counts of lactobacilli, mutans streptococci, and candida were consistently and significantly associated with caries prevalence, as either DS or DMFS score, and buffering capacity was consistently inversely related to DMFS score. However, veillonella counts and salivary flow rate were not correlated with caries prevalence. Significant improvements in the associations were obtained when the results of more than one test were included using stepwise regression analysis. On an individual basis, at most, stepwise discriminant analysis identified the DMFS group correctly in 49% of all subjects, and the DS group in 47%.

Adolescent↗