Warner, P.Barr, H.Shepherd, N. A.Cadd, Verity Anne2009-09-212009-09-212002-05http://hdl.handle.net/1826/3689Barrett's oesophagus is a complication of gastro-oesophageal reflux disease and is the single most important predisposing factor for the development of adenocarcinoma of the oesophagus. New molecular markers are needed for early diagnosis and to monitor disease progression. Telomerase is a ribonuclear protein with reverse transcriptase activity, which uses its own RNA component as a template for the addition of telomeric repeats to the end of chromosomes. Telomerase activity has been studied during the neoplastic progression of Barrett's oesophagus using a TRAP based ELISA technique, which found telomerase to be reactivated early during . disease progression. A non-isotopic method of in situ hybridisation for the detection of the RNA component of telomerase has also been successfully developed. Plasminogen activation is an inducible extracellular proteolytic system involved in the regulation of cellular interactions and invasion. The components of the urokinase-type Plasminogen Activator system have been fully investigated during the progression of Barrett's oesophagus to adenocarcinoma utilising immunohistochemistry and ELISA techniques. Changes in the expression of this invasive phenotype were found to occur late during disease progression in malignant tissues. Two-oesophageal cell-lines have been characterised using molecular biological techniques to detect a range of molecular markers to produce ex vivo models of oesophageal adenocarcinoma and oesophageal squamous cell carcinoma. In order to assess the effects of bile salts and acidity on oesophageal tissues these celllines were then utilised as ex vivo models. Exposure to acidic conditions both alone and with bile salts altered the morphological appearance of the cells and disrupted adhesion molecules in the cellular membrane. Investigations into both telomerase reactivation and the plasminogen activator system have provided new information concerning the nature and timing of molecular changes during the Barrett's metaplasia/dysplasia/ adenocarcinoma sequence.enThesis or dissertation