A research report submitted to the Faculty of Health Sciences, University of Witwatersrand, Johannesburg, in partial fulfillment of the degree of Master of Science in the branch of Dentistry / Orthokeratinised jaw cyst (OJC) is an entity distinct from odontogenic keratocyst (OKC) but that has not been fully characterised at the molecular level. The aim of this study was to compare the proliferative activity between the epithelial linings of OKC and OJC by immunohistochemical staining for Ki-67 and cyclin D1. The total numbers of Ki-67 and cyclin D1 positively (+) stained cells/10 consecutive lengths of a light microscope calibration ruler were counted for each case (OKC, n=15; OJC, n=15) and statistically compared in the basal compartment, suprabasal compartment and full thickness of the cyst lining between the 2 cyst types. OJC showed significantly fewer Ki-67+ cells and cyclin D1+ cells than OKC, consistent with the clinically more indolent behaviour of the OJC. Ki-67 expression was mainly detected in the suprabasal compartment in OKC. Expression of Ki-67 was more uniform in OJC and notably without a significant predilection for the suprabasal compartment. The accumulation of Ki-67 positive cells suprabasally in OKC raises the possibility that a process of asymmetrical cell division may be operational in OKC. Expression between Ki-67 and cyclin D1 differed significantly both quantitatively and by distribution pattern in OKC and OJC, which suggests that the presence of the cyclin D1 protein may not necessarily reflect production of this molecule by cycling cells in OKC and OJC.

Azotobacter vinelandii 12837 was grown in Burk's glucose media and transferred onto Burk's n-butanol agar plates to allow for the formation of cysts. The patterns of the vegetative cell proteins were compared for each successive day of cyst formation, using the polyacrylamide gel isoelectric focusing technique. The findings revealed that, as the cysts developed to maturity, definite changes occurred in the protein constitution, indicative of the biochemical and physiological changes which cells undergo during cyst development. Also, as a control to show that the changes in protein patterns during encystment were not due to physiological condition, Azotobacter vinelandii strain OP was grown in three different media, and proteins from the cells were compared using PAGIF.

published_or_final_version / Dentistry / Master / Master of Dental Surgery

No description available.

No description available.

In 2005 the World Health Organisation classified the odontogenic keratocyst (OKC) as a benign cystic neoplasm, using the term keratocystic odontogenic tumour. Significantly higher expression of proto-oncogenes and loss of expression of tumour suppressor genes have been demonstrated in the OKC when compared to more indolent jaw counterparts. This together with the higher mitotic activity in the epithelial lining of OKC could explain the aggressive behaviour of the OKC consistent with that of benign neoplasms. The BCL-6 proto-oncogene was identified in 1993 as a transcription factor whose deregulated expression is associated with B-cell non-Hodgkin lymphomas. In epithelial neoplasms, the BCL-6 transcription factor is associated with continuous growth and its absence triggers apoptosis. It has been suggested that BCL-6 may also participate prominently in the process of differentiation of epithelial cells. The aim of the study was to evaluate BCL-6 protein expression in the dentigerous cyst (n=10), radicular cyst (n=10) and OKC (n=20) by immunohistochemistry. Expression of BCL-6 was significantly higher in the OKC than in the dentigerous cyst and radicular cyst. In the OKC BCL-6 further showed a distinct predilection for the suprabasal compartment while in the dentigerous and radicular cysts the staining tended to be uniform throughout all the cell layers of the cyst lining. The study findings suggest that BCL-6 may play a role in the regulation of the suprabasal proliferative compartment of the OKC and in the keratinising epithelial cell differentiation of the OKC.

Thesis (M.D.)--Boston University

Thesis (Ph. D.)--University of Queensland, 2001. / Includes bibliographical references.

published_or_final_version / Anatomy / Master / Master of Philosophy

No description available.