Biophysical studies of the intracellular domains of the EGFR family of Receptor Tyrosine Kinases

The epidermal growth factor receptor and its three orthologues, HER2, HER3 and HER4 have been the subject of intensive basic, clinical and translational research due to their involvement in cancers. These proteins are part of elaborate networks that interact with a myriad of other molecules to effect diverse signaling pathways and affect cellular processes such as migration, apoptosis, cell differentiation and so on. In addition to the formation of preformed dimers, it is well established that ligand engagement leads to receptor dimerization in all family members, except HER2. In the past decade, it has been shown that their intracellular domains dimerize in an asymmetric fashion where the C-lobe of the donor kinase interacts extensively with the Nlobe of the receiver kinase. This structural model is critical for activation of the receiver kinase and subsequent phosphorylation of the C-terminal tail. While the structures of the different domains have been solved, minimum structural and biophysical studies have been performed on the C-terminal tails. In this thesis, we use multiple approaches to characterize the C-terminal tails of EGFR and HER3, and show that they are intrinsically disordered regions of these receptors. We also developed a strategy that has been employed to site-specifically fluorophore-label the EGFR kinase domain, and would serve as a biological probe to directly measure EGFR kinase domain dimerization on lipid surfaces

Adaptation of the Wound Healing Questionnaire universal-reporter outcome measure for use in global surgery trials (TALON-1 study): mixed-methods study and Rasch analysis

BackgroundThe Bluebelle Wound Healing Questionnaire (WHQ) is a universal-reporter outcome measure developed in the UK for remote detection of surgical-site infection after abdominal surgery. This study aimed to explore cross-cultural equivalence, acceptability, and content validity of the WHQ for use across low- and middle-income countries, and to make recommendations for its adaptation.MethodsThis was a mixed-methods study within a trial (SWAT) embedded in an international randomized trial, conducted according to best practice guidelines, and co-produced with community and patient partners (TALON-1). Structured interviews and focus groups were used to gather data regarding cross-cultural, cross-contextual equivalence of the individual items and scale, and conduct a translatability assessment. Translation was completed into five languages in accordance with Mapi recommendations. Next, data from a prospective cohort (SWAT) were interpreted using Rasch analysis to explore scaling and measurement properties of the WHQ. Finally, qualitative and quantitative data were triangulated using a modified, exploratory, instrumental design model.ResultsIn the qualitative phase, 10 structured interviews and six focus groups took place with a total of 47 investigators across six countries. Themes related to comprehension, response mapping, retrieval, and judgement were identified with rich cross-cultural insights. In the quantitative phase, an exploratory Rasch model was fitted to data from 537 patients (369 excluding extremes). Owing to the number of extreme (floor) values, the overall level of power was low. The single WHQ scale satisfied tests of unidimensionality, indicating validity of the ordinal total WHQ score. There was significant overall model misfit of five items (5, 9, 14, 15, 16) and local dependency in 11 item pairs. The person separation index was estimated as 0.48 suggesting weak discrimination between classes, whereas Cronbach's α was high at 0.86. Triangulation of qualitative data with the Rasch analysis supported recommendations for cross-cultural adaptation of the WHQ items 1 (redness), 3 (clear fluid), 7 (deep wound opening), 10 (pain), 11 (fever), 15 (antibiotics), 16 (debridement), 18 (drainage), and 19 (reoperation). Changes to three item response categories (1, not at all; 2, a little; 3, a lot) were adopted for symptom items 1 to 10, and two categories (0, no; 1, yes) for item 11 (fever).ConclusionThis study made recommendations for cross-cultural adaptation of the WHQ for use in global surgical research and practice, using co-produced mixed-methods data from three continents. Translations are now available for implementation into remote wound assessment pathways