Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M. D. S.)--University of Hong Kong, 2003. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Also available online.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

published_or_final_version / Dentistry / Master / Master of Philosophy

published_or_final_version / Dentistry / Master / Master of Dental Surgery

Three leaves of errata inserted before title page. / Bibliography: leaves 150-181. / xi, 181 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Determines whether growing cells of F. nucleatum ATCC 25586 could actually utilise peptides to provide the energy-yielding amino acid residues. Overall shows the important role of aminopeptidase in the nutrition and survival of F. nucleatum. / Thesis (Ph.D.)--University of Adelaide, Dept. of Dentistry, 1998

Doctor of Philosophy / Profound perturbation of epithelial structure is a characteristic feature of the immunopatholoical response to bacterial antigens considered to be central in the pathogenesis of the destructive lesion of periodontitis. The pathological basis for the disturbance of epithelial structure is not understood. It was demonstrated that the structural integrity and functional differentiation of the lining epithelium is compromised in relation to inflammatory changes associated with destructive periodontitis. In the pathological lining epithelium of the periodontal pocket there was a marked reduction of epithelial cadherin important in intercellular adhesion, of involucrin, a marker of terminal differentiation, and of the gap junction connexions that form intercellular communication channels. These changes were associated with alterations of filamentous actin expression, collectively indicating profound perturbation of epithelial structure. The data reported support the concept that the ability of the pathological lining epithelium to function as an effective barrier against the ingress of microbial products into the tissues is severely compromised (Ye et al., 2000). In addition, a recent study (Ye et al., 2003) by Western analysis of serum IgG from all 22 patients with chronic periodontitis tested indicated recognition of multiple epithelial components in individual patterns. In contrast, subjects with a healthy periodontium displayed only trace recognition of epithelial antigens. Levels of epithelial-reactive antibodies were significantly correlated with attachment loss as an indication of disease activity. To investigate a possible relationship between the bacterial flora adjacent to the diseased sites and the presence of epithelial-reactive antibodies, subgingival plague samples were taken from deep periodontal pockets and cultured anaerobically. Gram positive bacteria containing antigens potentially cross-reactive with epithelial cells were reproducibly isolated by probing membrane colony lifts with affinity-isolated (epitheial-specific) antibodies. The bacteria were identified as streptococci (S. mitis, S. constellatus and two S. intermedius strains) and Actinomyces (A. georgiae, and A. sp. oral clone) by 16S rDNA sequence homology. Recognition by affinity-isolated antibodies of antigens from the captured organisms was confirmed by Western analysis. Conversely, absorption of affinity-isolated antibodies with bacterial species specifically reduced subsequent recognition of epithelial antigens. To identify the auto-antigens, a human keratinocyte cDNA expression library in Lambda phage was probed using a pooled sera. Groups of responders were detected for CD24 (a recently described adhesion molecule also known as P-selectin ligand), antioxidant protein 2 (a newly recognised member of the thiol-dependment anti-oxidant proteins), lavtate dehydrogenase A, the transcription factor NFAT5, and for three genes encoding novel proteins. Six identified bacteria, especially S intermedius were demonstrated to absorb antibodies reaching with identified auto-antigens in patterns varying between individuals. This evidence indicated that during the course of periodontits, subjects develop increased levels of antibodies to common oral bacteria amongst which are included tissue cross-reactive antigens. Periodontitis could therefore present a risk for the subsequent initiation or exacerbation of a broad spectrum of disease processes including autoimmune, inflammatory, proliferative and degenerative disorders.

Thesis (Ph.D.) OGI School of Science & Engineering at OHSU, March 2008. / Includes bibliographical references (leaves 105 - 114).