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Biomedical subjects

D G MacDonald

Publications and source records attributed to D G MacDonald.

At least 37 records · Page 2Linked to original sources
PubMed1997

The effect of diet on palatal prosthetic coverage in rats.

UNLABELLED: Previous studies have used a rate model for examination of the histopathology of oral candidiasis or mucosal coverage with dental prostheses. These studies have been complicated by the presence of accumulated debris between mucosa and prostheses. OBJECTIVES: The present study was undertaken to develop further the Wistar rat as a suitable animal model on which to study the effects of dental prostheses on oral mucosa. METHODS: The effects of three dietary regimes, used for 7 and 14 days, upon debris accumulation under denture-like appliances and measurable epithelial parameters were analysed by computerised planimetry. RESULTS: Individual variation in animal weights during the study was noted, with some appliance-wearing animals exhibiting a weight gain while others lost weight. A powdered diet used in a paste form gave the least accumulation of debris under appliances and the least differences between appliance wearers and controls. CONCLUSION: The use of the Wistar rat model utilising the past diet described is indicated for future investigation of the effect of prostheses on oral mucosa.

Acrylic Resins↗
PubMed1997

Search for Mycobacterium paratuberculosis DNA in orofacial granulomatosis and oral Crohn's disease tissue by polymerase chain reaction.

BACKGROUND: Although intestinal Crohn's disease has long been suspected to have a mycobacterial cause, possible mycobacterial involvement in orofacial granulomatosis (OFG) and oral lesions of Crohn's disease has not yet been investigated. AIMS: As the slow growing Mycobacterium paratuberculosis has been implicated in the aetiology of intestinal Crohn's disease, the potential involvement of this mycobacterial species in OFG and oral lesions of Crohn's disease was investigated. PATIENTS: To attempt detection of the organism in OFG and oral Crohn's disease tissue samples, a polymerase chain reaction (PCR) assay was used on archival formalin fixed, paraffin wax embedded oral tissue sections from 30 patients with OFG, seven with Crohn's disease, and 12 normal controls. METHODS: The PCR assay used was based on primers targeting the 5' region of the multicopy IS900 DNA insertion element of the M paratuberculosis genome. In order to achieve maximum sensitivity, two rounds of PCR were carried out and amplicons confirmed by Southern blot hybridisation to a digoxigenin labelled IS900 DNA probe. RESULTS: None of the OFG and oral lesions of Crohn's disease samples were positive for M paratuberculosis and all normal controls were also negative. CONCLUSIONS: These results suggest that M paratuberculosis may not be a major aetiological agent in OFG or oral Crohn's disease lesions, although the use of paraffin wax embedded tissue as opposed to fresh tissue as a sample source could underestimate the true prevalence of the organism.

Blotting, Southern↗
PubMed1997

Lag screw fixation of an extensor process fracture in a foal with flexural deformity.

A 4-month-old colt with stage I flexural deformity of the distal interphalangeal joint was diagnosed as having a type IV nondisplaced fracture of the extensor process of the 3rd phalanx. An inferior check ligament desmotomy and internal fixation of the fracture were performed. Favorable long-term results for internal fixation of extensor process fractures are presented.

Animals↗
PubMed1996

Cheilo-candidosis in an adult.

A rare case of candidal infection of the lips is presented. Predisposing factors appeared to be intra-oral candidal carriage, actinic lip damage and Sjögren's syndrome. Systemic antifungal therapy with fluconazole resolved the initial infection and a subsequent recurrence.

Adult↗
PubMed1996

Analysis of immunoglobulin-synthesizing cells in human dental periapical lesions by in situ hybridization and immunohistochemistry.

Immunoglobulin (Ig) kappa (kappa) and lambda (lambda) light chain mRNA-expressing cells were investigated by in situ hybridization (ISH) to assess the local humoral immune response in human dental periapical lesions. Twenty-seven biopsy samples (17 periapical granulomas and 10 radicular cysts) were examined. Both types of light chain mRNA-positive cells were detected in formalin-fixed/paraffin-embedded tissue sections in all samples. Plasma cells showed weak to strong cytoplasmic staining with both probes and background staining was negligible. The ISH methodology is specific and sensitive in detecting Ig light chain mRNAs and retains cell morphology well. kappa to lambda ratios showed moderate variability for both granulomas and cysts (mean = 1.66 +/- 0.85 SD, 1.47 +/- 0.51, respectively). There was no significant difference in light chain distribution between granulomas and cysts. Ig kappa and lambda light chain proteins were also studied by immunohistochemistry (IHC) but the results were disappointing due to excessive background staining. This study confirms that Ig is locally produced in periapical lesions and that the ISH method localises Ig light chain-containing cells better than IHC. The wide variability in kappa/lambda ratio may support the concept of non-specific multibacterial infection in these lesions.

Adult↗
PubMed1995

Use of mesenteric lymphangiography in a calf with chylothorax and chyloperitoneum.

Lymphatic abnormalities resulting in chylous effusion into a body cavity are uncommon in domestic animals. In a 6-day-old calf admitted to our hospital because of failure to suckle and abdominal distention, however, mesenteric lymphangiography revealed an obstruction of lymphatic flow. Laparoscopic examination of the abdomen was unsuccessful. Fluid accumulation was resolved in this calf by drainage. In cattle with chylothorax and concurrent chyloperitoneum in which a traumatic lesion of the thoracic duct is possible, conservative management, with drainage and supportive treatment, should be attempted prior to considering surgical intervention.

Animals↗
PubMed1995

The influence of rate of cell entry to S phase on the labelling index of human buccal epithelium.

The physiological basis of the circadian rhythm in cell kinetics in human epithelia remains unclear. A 24-h periodicity in the labelling index (LI) of human buccal epithelium has been demonstrated previously. A double-labelling technique in vitro using tritiated deoxythymidine was used here to examine fluctuations in the time spent in S phase (Ts) and the rate of cell entry to S phase (S influx). While the range in Ts values was limited (5.1-6.9 h), influx to S phase ranged from 0 to 1.26% per hour at six different time periods. An increase in the S influx was apparent around 18:00 h leading to a peak LI 4 h later. These preliminary data indicate that the most likely kinetic mechanism related to circadian variations in LI is a variable G1-S influx at this site.

Adult↗
PubMed1995

Post-irradiation changes in the blood vessels of the adult human mandible.

Changes in the inferior alveolar artery and periosteal vessels of the post-irradiation mandible have been investigated. The inferior alveolar artery underwent comparatively little change, stenosis being noted in just over half the specimens examined. The number of periosteal arteries and veins increased, the changes being most marked on the body where the effective tissue dose of radiation was highest. The increase in periosteal vessels was independent of stenosis of the inferior alveolar artery.

Aged↗
PubMed1995

Basal cell cytoplasmic autoantibodies in oral lichenoid reactions.

One hundred sixty-one patients with a clinical diagnosis of an oral lichenoid reaction were evaluated serologically for circulating autoantibodies toward basal cell membrane components. The study group comprised 119 women and 42 men with a median age of 59 and 55 years, respectively. Most patients (n = 144) had an oral mucosal biopsy undertaken. Serologic investigation aimed to identify an IgG antibody that, under immunofluorescent staining, produced an annular fluorescence of basal cells and that has been referred to as basal cell cytoplasmic antibody. These basal cell cytoplasmic antibodies were significantly associated with systemic drug usage, histologic diagnosis of a lichenoid reaction, and a unilateral intraoral distribution of the clinical lesion. In the diagnosis of oral lichenoid reactions precipitated by drug therapy, the basal cell cytoplasmic phenomenon may be a useful adjunct to clinical and histologic investigation.

Adolescent↗
PubMed1995

Epithelial cell kinetics in oral leukoplakia.

Cell proliferation in oral leukoplakia has been studied by estimating the number of cells in the S phase using in vitro 3H thymidine labelling. The labelling index was found to be increased 1.77 fold in leukoplakias compared to the clinically normal control sites (P < 0.005). This rise in labelling index was found to be related to an increase in the proportion of the cells in the basal cell layer engaged in cell production. Both leukoplakia and the control specimens showed epithelial atypia, although in the latter samples this was mild yet suggestive of a possible field change in the oral epithelium of a small group of tobacco users. A significant positive correlation was found between the epithelial atypia score and the labelling index. This raises the possibility of using the labelling index as an objective prognostic marker in assessing potential malignancy in oral leukoplakia lesions.

Analysis of Variance↗
PubMed1994

Flow cytometric analysis of DNA content in squamous carcinoma of the tongue: the relationship to host and tumour factors and survival.

Cellular DNA content has been found to be an important prognostic factor in many human tumours, yet within the head and neck region few studies have examined its effect on survival and in those that have, findings differ. Eighty-one consecutive patients with squamous carcinoma of the tongue mainly treated by surgery and post-operative radiotherapy were studied. The DNA content of archival paraffin embedded tumours was measured by flow cytometry. Fifty-seven tumours were diploid and 24 were aneuploid. There was no association between ploidy status and age, sex, tumour size or nodal status. Ploidy status was not related to survival. These findings indicate that analysis of tumour DNA content in squamous carcinoma of the tongue does not provide any additional prognostic information for the individual patient.

Aneuploidy↗
PubMed1994

An examination of the occurrence of surgical wound infection following equine orthopaedic surgery (1981-1990).

Post operative surgical wound infection rates were determined 452 cases of equine orthopaedic surgery performed at the Western College of Veterinary Medicine, Saskatoon, Saskatchewan, between January 1, 1981 and December 31, 1990. Only surgical procedures classified as clean or clean-contaminated by the National Research Council were included in this study. The overall post operative infection rate was 10.0% (45 of 452). Clean surgeries (n = 433) had an 8.1% infection rate while clean-contaminated surgeries (n = 19) had a 52.6% infection rate. Information collected from the medical records was used in univariate and multivariate logistic regression models to evaluate significant determinates of post operative infection. Significant determinates of post operative infection were: surgical classification, orthopaedic involvement, duration of surgery, administration of preoperative antibiotics and gender. Clean-contaminated surgeries had an increased risk of infection compared to clean surgeries (odds ratio (OR) = 24.3), procedures involving long bones had an increased risk of infection compared to procedures involving articular surfaces (OR = 5.1), surgeries lasting 90 minutes or longer had an increased risk of infection compared to those less than 90 minutes (OR = 3.6), administration of preoperative antibiotics was associated with an increased risk of infection (OR = 4.6) and female patients were 2.6 times more likely to develop post operative infection than male patients.

Animals↗
PubMed1993

Diurnal variation in labelling index in human buccal epithelium.

Diurnal variations in the number of DNA-synthesizing cells (labelling index) in human buccal epithelium were studied by in vitro pulse labelling with tritiated deoxythymidine. Eleven male volunteers provided 33 biopsy specimens at six time periods. The results showed a 24-h periodicity in the labelling index in this tissue. The mean peak labelling index obtained at 22:00 h (3.20 +/- 0.18) was significantly different from the means obtained at the rest of the times. The 24-h mean labelling index (labelled cells/100 cells) was 2.48 +/- 0.47 for three subjects who volunteered samples at all six time periods. The labelling index obtained around the middle part of the day for all subjects (2.44-2.59) appears to be representative of a 24-h basal or reference value.

Adult↗
PubMed1992

Rat palatal histology related to denture-like appliances.

Two designs of palatal denture-like appliance were fitted to rats. Tooth- and tissue-borne appliances caused changes in epithelial thickness and keratin thickness, but these varied with anatomical site and type of appliance. A single inoculation of Candida albicans at the time of insertion of the appliance failed to establish infection consistently. Debris accumulation under the appliances was a problem which will restrict long-term studies with this model.

Animals↗