Biomedical subjects

D G MacDonald

Publications and source records attributed to D G MacDonald.

118 records · Page 7Linked to original sources

PubMedDate not supplied

Routes of entry of squamous cell carcinoma to the mandible.

A recent preliminary report of a study to determine the patterns of invasion of squamous cell carcinoma to the nonirradiated edentulous mandible indicated that tumor entered mainly through the residual alveolar occlusal ridge. This study has now been extended and includes both nonirradiated and irradiated mandibles. Of a total of 46 nonirradiated mandibles (10 partially dentate and 36 edentulous) invaded by tumor, 41 were invaded through the occlusal surface. This confirms the findings of the preliminary report. These findings indicate that there is a rational basis on pathologic grounds for adopting a conservative approach to the nonirradiated mandible. In 16 irradiated mandibles, the routes of tumor entry were found to be much more variable than in the nonirradiated mandible. In 16 irradiated mandibles, the routes of tumor entry were found to be much more variable than in the nonirradiated mandible, and multiple foci of tumor invasion of the bone were often present wherever tumor in adjacent soft tissues approached the bone. This variability of tumor entry means that a conservative approach to mandibular excision cannot be pursued in the previously irradiated mandible and full-thickness segmental resection is necessary if bone involvement appears likely.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Reactive changes in the mandible in the presence of squamous cell carcinoma.

A series of 80 mandibles, which were removed as part of composite resections for primary intraoral squamous cell carcinoma, was examined. Of these, 58 were nonirradiated and 22 were previously irradiated. Several changes were observed in the nonirradiated mandible in response to invading tumor. Deposition of new bone was obvious on the periosteal and endosteal surfaces. Osteoclastic resorption of bone was prominent and there was replacement of hemopoietic marrow by fibrous tissue. By contrast, it was found in the irradiated specimens that osteoblastic activity was absent but that osteoclastic activity persisted. The hemopoietic marrow was replaced by fibrous tissue. The lack of osteoblastic activity was interpreted as being due to irradiation. The extent of these changes and their relationship to the invading tumor have implications for both surgeon and pathologist.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

The effect of chairside relining materials on rat palatal mucosa.

OBJECTIVES: To investigate the effects of denture relining materials on oral mucosa in vivo in a rat model. METHODS: Denture-like appliances covering the palate in Wistar rats were relined with a resilient soft linting material and a hard 'chairside' relining material. The effects on the palatal epithelium were studied by quantitative analysis using computerized planimetry. RESULTS: The relining materials caused an increase in the thickness of the keratinized layer, while not increasing the total epithelial thickness. CONCLUSIONS: Relining materials are not totally without effect on oral mucosa. Further in vivo research is indicated.

Acrylic Resins↗

PubMedDate not supplied

Proximal interphalangeal joint arthrodesis in 34 horses using two parallel 5.5-mm cortical bone screws.

OBJECTIVE: To report clinical experience with arthrodesis of the proximal interphalangeal joint in horses using two parallel 5.5-mm cortical bone screws placed in lag fashion. STUDY DESIGN: Retrospective, clinical study. ANIMALS: Thirty-four horses, aged 1 to 19 years. METHODS: Medical records for all horses admitted (1991-1997) for pastern arthrodesis using two 5.5-mm ASIF cortical bone screws, in parallel orientation, and placed in lag fashion by use of a combined aiming device to facilitate accuracy were reviewed. Signalment, lameness diagnosis, duration of lameness, limb(s) involved, and outcome were recorded. Criteria for successful outcome were determined as return to previous level of function or future intended athletic use. RESULTS: Thirty-nine proximal interphalangeal joint arthrodeses were performed on 34 horses. One horse was euthanatized in the recovery room and was excluded from data analysis. Successful outcome occurred in 85% of frontlimbs and 89% of hindlimbs. Failure occurred in 5 joints; 1 horse had lameness directly associated with surgery, whereas 4 horses had unrelated lameness. CONCLUSION AND CLINICAL RELEVANCE: Age, breed, and initial disease did not affect outcome. Arthrodesis of the proximal interphalangeal joint by use of two 5.5-mm ASIF cortical bone screws, in parallel orientation, placed in lag fashion by use of a combined aiming device, resulted in sound use of the limb in >85% of the joints with shortened postoperative coaptation.

Animals↗

PubMedDate not supplied

Repair of complete dorsal fracture of the proximal phalanx in two horses.

Simple complete dorsal fractures of the proximal phalanx were repaired in 2 mature pleasure horses with cortical bone screws placed in lag fashion. Healing occurred within 12 weeks and both horses returned to their previous performance level of light pleasure riding within 6 months of injury.

Animals↗

PubMedDate not supplied

Computerised planimetric and stereological analyses of histological and cytological parameters in dysplastic atrophic epithelium and carcinoma.

This report analysed two lesions, of the Oral cavity, (atrophic dysplastic epithelium and oral squamous cell carcinoma) using computerized planimetry and point counting stereological methods. Three cytological, and histological parameters were analysed at a time. Results indicate a significant difference between the cell size, and nucleocytoplasmic ratio's of the two lesions when analysed (P<0.0001). The nuclear area measurement did not differ when the figure for the two lesions were compared. Study confirms the efficacy of objective analyses of tissue pathology of the oral cavity.

Aged↗

PubMedDate not supplied