The caudal fin of zebrafish (danio rerio) is often used to study regeneration thanks to its extraordinary regenerative ability, easy access, and relative simplicity in structure. Branching morphogenesis is observed in many organs, including lungs and salivary glands in mammals, as well as the fin rays in zebrafish and is thought to follow unifying principles. An important developmental gene, sonic hedgehog a (shha), has been shown in other studies to play an essential role in the branch formation. Previous studies in our lab have shown that the transient depletion of the shha-expressing cells following laser ablation of the shha-expressing cells in the regenerating caudal fin results in a delay of fin rays branch formation. In order to study the long-term effect of ablating the shha-expressing cells, I generated a new zebrafish transgenic line (Tg)(2.4shha:CFP-NTR-ABC) to perform a conditional cell ablation using the Metronidazole/Nitroreductase (Mtz/NTR) system. Preliminary data suggest that cell ablation using the Mtz/NTR system is successful in the Tg(2.4shha:CFP-NTR-ABC) embryos. In addition, short-term ablation of the shha-expressing cells through Mtz/NTR system delays branch formation during caudal fin regeneration of the Tg(2.4shha:CFP-NTR-ABC) adult fish. Further work will involve the analysis of the effects of the long-term ablation of the shha-expressing cells and the involvement of other signaling pathways in the ray branching formation during zebrafish caudal fin regeneration. This study can provide insights into understanding of the molecular mechanisms underlying branching morphogenesis in various organs. During the course of the above project, I have observed an organ-wide response to local injury in the zebrafish caudal fin. In this study, I have shown, for the first time, an immediate organ-wide response to partial fin amputation characterized by the damage of blood vessels, nerve fibers and the activation of inflammatory response in the non-amputated tissues. I established that the adult zebrafish caudal fin serves as an excellent model for the study of the organ-wide response to local injury, and such study may provide new insights into the field of regenerative medicine in which stimulating regeneration locally may trigger responses in unintended locations.   Résumé La nageoire caudale du poisson zèbre (danio rerio) est souvent utilisée pour étudier les mécanismes de régénération à cause de son extraordinaire capacité de régénération, son accès facile, et sa relative simplicité structurale. La morphogenèse de branches est observée dans plusieurs organes incluant les poumons et les glandes salivaires chez les mammifères ainsi que les rayons des nageoires du poisson zèbre et est supposée suivre des principes communs. Un important gène de développement, sonic hedgehog a (shha), joue un rôle essentiel dans la formation des branches. Des études précédentes effectuées dans notre laboratoire ont montré que l’absence transitoire des cellules exprimant shha dans des expériences d’ablation au rayon laser induit un délai de la formation des branches dans les rayons au cours de la régénération de la nageoire caudale. Afin d’étudier les effets de l’ablation à long terme des cellules exprimant shha, j’ai fait un nouvelle lignée transgénique de poisson zèbre Tg(2.4shha:CFP-NTR-ABC) pour effectuer une ablation cellulaire conditionnelle à l’aide du système Métronidazole / Nitroréductase (Mtz/NTR). Mes données préliminaires suggèrent que l’ablation cellulaire à l’aide du système Mtz/NTR fonctionne sur les embryons Tg(2.4shha:CFP-NTR-ABC). De plus, l’ablation à court terme des cellules exprimant shha à l’aide du système Mtz/NTR induit un délai de la formation des branches au cours de la régénération des rayons la nageoire caudale des poissons adultes Tg(2.4shha:CFP-NTR-ABC). Des études supplémentaires incluront l’analyse des effets de l’ablation à long terme des cellules exprimant shha et le rôle d’autres cascades de signalisation dans la formation des branches des rayons au cours de la régénération de la nageoire caudale du poisson zèbre. Cette étude pourrait fournir des informations concernant la compréhension des mécanismes moléculaires sous-jacents à la formation de branches dans des organes variés. Au cours de l’étude décrite ci-dessus, j’ai fait l’observation d’une réponse globale de toute la nageoire caudale à une blessure locale. Dans cette étude, j’ai montré pour la première fois, une réponse immédiate et globale après amputation partielle de la nageoire. Cette réponse est caractérisée par des lésions des vaisseaux sanguins, des fibres nerveuses et par l’activation d’une réponse inflammatoire dans les tissus non-amputés. J’ai établi que la nageoire caudale du poisson zèbre adulte est un excellent modèle pour l’étude de la réponse globale d’un organe à une lésion locale. Une telle étude pourrait fournir de nouvelles informations pertinentes à la médecine régénérative qui, en visant à stimuler la régénération de façon locale, peut entraîner des réponses dans des domaines non voulus.

The caudal fin of zebrafish (danio rerio) is often used to study regeneration thanks to its extraordinary regenerative ability, easy access, and relative simplicity in structure. Branching morphogenesis is observed in many organs, including lungs and salivary glands in mammals, as well as the fin rays in zebrafish and is thought to follow unifying principles. An important developmental gene, sonic hedgehog a (shha), has been shown in other studies to play an essential role in the branch formation. Previous studies in our lab have shown that the transient depletion of the shha-expressing cells following laser ablation of the shha-expressing cells in the regenerating caudal fin results in a delay of fin rays branch formation. In order to study the long-term effect of ablating the shha-expressing cells, I generated a new zebrafish transgenic line (Tg)(2.4shha:CFP-NTR-ABC) to perform a conditional cell ablation using the Metronidazole/Nitroreductase (Mtz/NTR) system. Preliminary data suggest that cell ablation using the Mtz/NTR system is successful in the Tg(2.4shha:CFP-NTR-ABC) embryos. In addition, short-term ablation of the shha-expressing cells through Mtz/NTR system delays branch formation during caudal fin regeneration of the Tg(2.4shha:CFP-NTR-ABC) adult fish. Further work will involve the analysis of the effects of the long-term ablation of the shha-expressing cells and the involvement of other signaling pathways in the ray branching formation during zebrafish caudal fin regeneration. This study can provide insights into understanding of the molecular mechanisms underlying branching morphogenesis in various organs. During the course of the above project, I have observed an organ-wide response to local injury in the zebrafish caudal fin. In this study, I have shown, for the first time, an immediate organ-wide response to partial fin amputation characterized by the damage of blood vessels, nerve fibers and the activation of inflammatory response in the non-amputated tissues. I established that the adult zebrafish caudal fin serves as an excellent model for the study of the organ-wide response to local injury, and such study may provide new insights into the field of regenerative medicine in which stimulating regeneration locally may trigger responses in unintended locations.   Résumé La nageoire caudale du poisson zèbre (danio rerio) est souvent utilisée pour étudier les mécanismes de régénération à cause de son extraordinaire capacité de régénération, son accès facile, et sa relative simplicité structurale. La morphogenèse de branches est observée dans plusieurs organes incluant les poumons et les glandes salivaires chez les mammifères ainsi que les rayons des nageoires du poisson zèbre et est supposée suivre des principes communs. Un important gène de développement, sonic hedgehog a (shha), joue un rôle essentiel dans la formation des branches. Des études précédentes effectuées dans notre laboratoire ont montré que l’absence transitoire des cellules exprimant shha dans des expériences d’ablation au rayon laser induit un délai de la formation des branches dans les rayons au cours de la régénération de la nageoire caudale. Afin d’étudier les effets de l’ablation à long terme des cellules exprimant shha, j’ai fait un nouvelle lignée transgénique de poisson zèbre Tg(2.4shha:CFP-NTR-ABC) pour effectuer une ablation cellulaire conditionnelle à l’aide du système Métronidazole / Nitroréductase (Mtz/NTR). Mes données préliminaires suggèrent que l’ablation cellulaire à l’aide du système Mtz/NTR fonctionne sur les embryons Tg(2.4shha:CFP-NTR-ABC). De plus, l’ablation à court terme des cellules exprimant shha à l’aide du système Mtz/NTR induit un délai de la formation des branches au cours de la régénération des rayons la nageoire caudale des poissons adultes Tg(2.4shha:CFP-NTR-ABC). Des études supplémentaires incluront l’analyse des effets de l’ablation à long terme des cellules exprimant shha et le rôle d’autres cascades de signalisation dans la formation des branches des rayons au cours de la régénération de la nageoire caudale du poisson zèbre. Cette étude pourrait fournir des informations concernant la compréhension des mécanismes moléculaires sous-jacents à la formation de branches dans des organes variés. Au cours de l’étude décrite ci-dessus, j’ai fait l’observation d’une réponse globale de toute la nageoire caudale à une blessure locale. Dans cette étude, j’ai montré pour la première fois, une réponse immédiate et globale après amputation partielle de la nageoire. Cette réponse est caractérisée par des lésions des vaisseaux sanguins, des fibres nerveuses et par l’activation d’une réponse inflammatoire dans les tissus non-amputés. J’ai établi que la nageoire caudale du poisson zèbre adulte est un excellent modèle pour l’étude de la réponse globale d’un organe à une lésion locale. Une telle étude pourrait fournir de nouvelles informations pertinentes à la médecine régénérative qui, en visant à stimuler la régénération de façon locale, peut entraîner des réponses dans des domaines non voulus.

Introduction: After a brain injury there are often long term consequences impacting on QoL. However, this is a complex issue influenced by many factors. As someone recovers and adjusts it is likely that the way in which they evaluate QoL will also change. The theory of response shift suggests people will change the way they evaluate QoL in the face of changes in their life. The aim of this thesis is to investigate what influences a QoL judgement; examining the possibility of response shift. Methods: Quantitative and qualitative methods were used in 4 studies. These were a cross-sectional design utilising an individualised QoL measure (SEIQoL-DW); a longitudinal study utilising a ‘then-test’ approach; a cross-sectional questionnaire study; and a qualitative study using Interpretative Phenomenological Analysis. Study 1 (Ch.3) Results: Correlations between the QoL measures confirm the validity of the SEIQoL-DW; however, correlations were generally stronger for the simpler Hadorn Scale. There was little overall change in mean QoL when current and retrospective judgements were compared. There was evidence for a change in what areas of life were considered most important to QoL following injury. Study 2 (Ch.4) Results: Improvements in reported QoL between baseline and follow-up were small. A then-test indicates that any effect of response shift is small, and non-significant in the current research. There was also little evidence for reprioritisation or re-conceptualisation. Examination of other factors associated with QoL suggest that brain-injury specific factors (BIGI, RBANS) play a role in predicting QoL. Study 3 (Ch.5) Results: QoL was reported as worse post-injury on both Hadorn’s scale and the QOLIBRI-OS; a difference that was more pronounced on the QOLIBRI-OS. Differences were also reported in the importance of different areas of functioning. Change in QoL as measured by the QOLIBRI-OS was significantly influenced by disability as measured by the GOSE, emotional and informational support, and upwards social comparison. Optimism as measured by the LOT, but not upwards social comparison was a significant predictor of change on Hadorn’s scale; GOSE and emotional and informational support remain significant predictors. The GOSE, emotional and informational support, emotional coping styles and optimism were significant predictors of current QoL on the QOLIBRI-OS; and emotional and informational support and optimism were significant predictors of QoL on Hadorn’s scale. Little evidence was found to suggest that the factors proposed in Sprangers and Schwartz’s (1999) model of response shift have predicted relationships with QoL. Two candidate variables were studied: optimism and social support. However neither showed the predicted pattern of relationships. Nonetheless the study supports previous work indicating an influence of optimism and social support on QoL, and indicates that these warrant further study. There were systematic difference between current and retrospective ratings of importance of domains. The level of importance given to the areas of life defined by the QOLIBRI-OS is higher after injury than before, with the exception of “personal and social life” for which there is no significant difference. The areas of life chosen to reflect that which is measured by the GOSE (“work”, “close relationships”, and “social and leisure activities”) are rated as less important with the exception of “close relationships”. These findings provide further support for the idea that QoL domains are re-evaluated after brain injury. Study 4: This was an in depth qualitative investigation of the experience of recovery and adjustment following TBI. Semi-structured interviews and Interpretative Phenomenological Analysis (IPA) were used. Interviews were conducted with 4 men who were 3, 7, 12, and 18 years post injury. Main Outcome and Results: Themes emerging from the analysis were ‘Change: In Self and World’; ‘Reaching a point of realisation’; ‘Support’; ‘Adjusting to change/Coping with day to day life’; and ‘Participation, Goals and Focus’. These themes cover how participants felt both they and their lives had changed as a consequence of their injury; ways they went about coping and adjusting to changes; the importance of support; and the significance of social integration and participation in feeling satisfied with life. Summary and Conclusions: These studies provide evidence for response shift in different ways. There is little evidence for recalibration but there is some indication that reprioritization or reconceptualization may take place. Changes in how important different areas of life are before and after injury suggest that participants are changing the way they view and make evaluations of QoL. Factors identified as being important to QoL judgements were disability, social support (emotional and informational support identified in the questionnaire study and support in the IPA), upwards social comparison, and optimism. The IPA study suggests that functional outcome and participation are important after TBI; while also identifying ways of coping and providing an insight into the experience of recovery from brain injury. The different QoL measures used provides both evidence for their validity, but also evidence for the different conceptualisations of QoL that are measured by different instruments. The findings have implications both for understanding the QoL of the individual and for research on QoL after TBI.