Thesis (M.S.)--University of Michigan, 1982.

No description available.

No description available.

The alveolar epithelium is a key functional component of the air-blood barrier in the lung. Comprised of two morphologically distinct cell types, alveolar epithelial type I (ATI) and type II (ATII) cells, effective repair of the alveolar epithelial barrier following injury appears to be an important determinant of clinical outcome. The prevailing view suggests this repair is achieved by the proliferation of ATII cells and the transdifferentiation of ATII cells into ATI cells. Supplemental oxygen and mechanical ventilation are key therapeutic interventions in the supportive treatment of respiratory failure following lung injury, but the effects of hyperoxia and mechanical deformation in the injured lung, and on alveolar epithelial repair in particular, are largely unknown. The clinical impression however, is that poor outcome is associated with exposure of injured (repairing) epithelium to such iatrogenic ‘hits’. This thesis describes studies investigating the hypothesis that hyperoxia & mechanical deformation inhibit normal epithelial repair. The in vitro data presented demonstrate that hyperoxia reversibly inhibits the transdifferentiation of ATII-like cells into ATI-like cells with time in culture. Whilst confirming that hyperoxia is injurious to alveolar epithelial cells, these data further suggest the ATII cell population harbours a subpopulation of cells resistant to hyperoxia-induced injury. This subpopulation of cells appears to generate fewer reactive oxygen species and express lower levels of the zonula adherens protein E-cadherin. Using a panel of antibodies to ATI (RTI40) and ATII (MMC4 & RTII70) cell-selective proteins, the effect of hyperoxia on the phenotype of the alveolar epithelium in a rat model of resolving S. aureus-induced lung injury was investigated. These in vivo studies support the view that, under normoxic conditions, alveolar epithelial repair occurs through ATII cell proliferation & transdifferentiation of ATII cells into ATI cells, with transdifferentiation occurring via a novel intermediate (MMC4/RTI40-coexpressing) immunophenotype. However, in S. aureus-injured lungs exposed to hyperoxia, the resolution of ATII cell hyperplasia was impaired, with an increase in ATII cell-staining membrane and a reduction in intermediate cell-staining membrane compared to injured lungs exposed to normoxia alone. As hyperoxia is pro-apoptotic and known to inhibit ATII cell proliferation, these data support the hypothesis that hyperoxia impairs normal epithelial repair by inhibiting the transdifferentiation of ATII cells into ATI cells in vivo. The effect of mechanical deformation on alveolar epithelial cells in culture was investigated by examining changes in cell viability following exposure of epithelial cell monolayers to quantified levels of cyclic equibiaxial mechanical strain. In the central region of monolayers, deformation-induced injury was a non-linear function of deformation magnitude, with significant injury occurring only following exposure to strains greater than those associated with inflation of the intact lung to total lung capacity. However, these studies demonstrate for the first time that different epithelial cell phenotypes within the same culture system have different sensitivities to deformation-induced injury, with spreading RTI40-expressing cells in the peripheral region of epithelial cell monolayers and in the region of ‘repairing’ wounds being injured even at physiological levels of mechanical strain. These findings are consistent with the hypothesis that alveolar epithelial cells in regions of epithelial repair are highly susceptible to deformation-induced injury.

1 v. (various pagings) ; / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Faculty of Medicine, 1972

No description available.

Thesis (M.D.S.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 69-85).

Background: Removal of teeth results in both horizontal and vertical changes of hard and soft tissue dimensions. The magnitude of these changes is important for decision-making and comprehensive treatment planning, with provisions for possible solutions to expected complications during prosthetic rehabilitation. Objectives: to review all English dental literature to assess the magnitude of dimensional changes of both the hard and soft tissues of the alveolar ridge up to 12 months following tooth extraction in humans. Materials and methods: An electronic MEDLINE and CENTRAL search complemented by manual searching was conducted to identify randomized controlled clinical trials and prospective cohort studies on hard and soft tissue dimensional changes after tooth extraction. Only studies reporting on undisturbed post-extraction dimensional changes relative to a fixed reference point over a clearly stated time period were included. Assessment of the identified studies and data extraction was performed independently by two reviewers. Data collected were reported by descriptive methods. Weighted means and percentages of the dimensional changes over time were calculated where appropriate. Results: The search provided 3954 titles and 238 abstracts. Full text analysis was performed for 104 articles resulting in 20 studies that met the inclusion criteria. In human hard tissue, horizontal dimensional reduction (3.79 ± 0.23 mm) was more than vertical reduction (1.24 ± 0.11 mm on buccal, 0.84 ± 0.62 mm on mesial and 0.80 ± 0.71 mm on distal sites) at 6 months. Percentage vertical dimensional change was 11-22 % at 6 months. Percentage horizontal dimensional change was 32% at 3 months, and 29-63% at 6-7 months. Soft tissue changes demonstrated 0.4-0.5 mm gain of thickness at 6 months on the buccal and lingual aspects. Horizontal dimensional changes of hard and soft tissue (loss of 0.1 mm to 6.1 mm) was more substantial than vertical change (loss 0.9 mm to gain 0.4mm) during observation periods of up to 12 months, when study casts were utilised as a means of documenting the changes. Conclusions: Human re-entry studies showed horizontal bone loss of 29-63% and vertical bone loss of 11-22% after 6 months following tooth extraction. These studies demonstrated rapid reductions in the first 3-6 months that was followed by gradual reductions in dimensions thereafter. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

Background: Removal of teeth results in both horizontal and vertical changes of hard and soft tissue dimensions. The magnitude of these changes is important for decision-making and comprehensive treatment planning, with provisions for possible solutions to expected complications during prosthetic rehabilitation. Objectives: to review all English dental literature to assess the magnitude of dimensional changes of both the hard and soft tissues of the alveolar ridge up to 12 months following tooth extraction in humans. Materials and methods: An electronic MEDLINE and CENTRAL search complemented by manual searching was conducted to identify randomised controlled clinical trials and prospective cohort studies on hard and soft tissue dimensional changes after tooth extraction. Only studies reporting on undisturbed post-extraction dimensional changes relative to a fixed reference point over a clearly stated time period were included. Assessment of the identified studies and data extraction was performed independently by two reviewers. Data collected were reported by descriptive methods. Weighted means and percentages of the dimensional changes over time were calculated where appropriate. Results: The search provided 3954 titles and 238 abstracts. Full text analysis was performed for 104 articles resulting in 20 studies that met the inclusion criteria. In human hard tissue, horizontal dimensional reduction (3.79 ± 0.23 mm) was more than vertical reduction (1.24 ± 0.11 mm on buccal, 0.84 ± 0.62 mm on mesial and 0.80 ± 0.71 mm on distal sites) at 6 months. Percentage vertical dimensional change was 11-22 % at 6 months. Percentage horizontal dimensional change was 32% at 3 months, and 29-63% at 6-7 months. Soft tissue changes demonstrated 0.4-0.5 mm gain of thickness at 6 months on the buccal and lingual aspects. Horizontal dimensional changes of hard and soft tissue (loss of 0.1 mm to 6.1 mm) was more substantial than vertical change (loss 0.9 mm to gain 0.4mm) during observation periods of up to 12 months, when study casts were utilised as a means of documenting the changes. Conclusions: Human re-entry studies showed horizontal bone loss of 29-63% and vertical bone loss of 11-22% after 6 months following tooth extraction. These studies demonstrated rapid reductions in the first 3-6 months that was followed by gradual reductions in dimensions thereafter. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

Thesis (M.D.S.) - Department of Dental Health, University of Adelaide. / Typescript (photocopy).