Proton radiotherapy represents a rapidly developing alternative to photon based treatment for specific types of cancer. The therapeutic use of protons is fundamentally motivated by an advantageous depth-dose profile characterised by the “Bragg peak". The limitation of damage to healthy tissues surrounding a treatment region using protons presents an inherent advantage over photons. However, even though there is extensive experience in the clinical use of protons, there remains much to be learned regarding the relative biological effectiveness (RBE) of protons in relation to photons. The shortcoming of current knowledge is manifested in the large uncertainties in the relationship between RBE and the proton linear energy transfer (LET), since many aspects must be considered when utilising current datasets (different experimental conditions, biophysical models etc.). As a result, current clinical practice adopts a constant RBE value of 1.1 across the entire treatment region, irrespective of size, beam modulation, depth, cellular radiosensitivity, and dose. Focussing on the key biological endpoints of cell survival and DNA damage, this work presents a comparative investigation of the biological effectiveness of clinical proton beams using normal and radioresistant human cells. Significant cell killing RBE and DNA damage response variations along the proton beam path were observed, particularly in the distal region, coinciding with a sharp rise in LET. Experimental RBE values were in excellent agreement with local effect model predicted values, indicating that dose-averaged LET is a suitable predictor of proton biological effectiveness. In addition, using the key clinical strategy of dose fractionation, variations in the cell killing RBE were also observed. The work presented has demonstrated that there is considerable potential for the optimisation of proton radiotherapy through the use of a variable RBE model as opposed to the currently adopted generic value of 1.1

Ionising radiation is commonly used in radiation treatment of cancer to target cancerous cells. Upon entering a cell, ionising radiation can damage DNA directly or it can excite the cellular medium. The most abundant species produced following excitation of the medium is the low energy electron (LEE). LEE's can cause significant damage to DNA but the exact mechanism of this damage is unknown. This thesis investigates the indirect damage that LEEs do to DNA fragments, with particular emphasis on the influence of the surrounding water molecules. Using ab initio Molecular Dynamics, we investigated DNA-water systems, ranging from nucleobases to nucleotides. We found that water molecules in the environment are capable of forming hydrogen bonds with or transferring protons to the DNA fragment. In all these cases, when the DNA is H-bonded to or protonated by the water molecules, the energetic barriers to DNA damage reactions are affected. In the final parts of the thesis, we extended the research and investigated chemo-radiation therapy involving the chemotherapeutic agent cisplatin. We found once again that including the water environment around the DNA-cisplatin had an effect on the reactivity of this system with LEEs. Our results highlight the significant role that water molecules can play in DNA damage processes and demonstrate that it is therefore important to incorporate explicit water molecules in any simulation of the DNA damage process.

Up to 80% of patients who receive pelvic radiotherapy e.g. for prostate, cervical or bladder cancer, develop bladder dysfunction during treatment; characterised by urgency, increased frequency and impaired voiding ability which have a negative impact on patient quality of life. Irradiated animal models share a similar pathophysiology. Urodynamic analysis reveals a reduced bladder capacity and/or increased urination frequency within 1 week of pelvic irradiation. Functional abnormalities are attributed, at least in part to a damaged mucosal layer, evident within 24 hours of radiation exposure. However, mechanisms leading to disturbed bladder contractility have not been elucidated. Recently the mucosal layer has been shown to have a profound influence on detrusor contractility involving local and central signalling mechanisms. The impact of the mucosa on detrusor contractility in the irradiated bladder has never been assessed. The present study describes an early radiation-induced effect on detrusor contraction in guinea-pig bladder strips, specifically mediated by the mucosal layer. Nerve-evoked contractions were significantly reduced in intact but not mucosa-free bladder strips. Importantly K+ contractions were unaffected by irradiation indicating maintenance of Ca2+-sensitive contractile mechanisms in smooth muscle cells. These results demonstrate an early radiation-induced negative signalling effect on bladder function mediated by the mucosal layer. One week following in vivo irradiation in the mouse bladder, a mucosa-mediated negative signalling which again impaired nerve-evoked contractions, as well as ATP, CCh, and K+-evoked contractions was observed. Interestingly, nerve-evoked contraction in mucosa-free strips was similar to control implying the potential for normal strength voiding contraction; however, the relative contribution of cholinergic, purinergic and residual components was altered suggesting remodelling of underlying excitation-contraction coupling pathways. In addition, disturbed IC networks in the irradiated bladder were investigated with immunohistochemistry and TEM, demonstrating their sensitivity to radiation. In keeping with mucosa-mediated damage, we also report for the first time, elevated urinary NGF in prostate cancer patients undergoing radiotherapy associated with IPSS peak symptom severity and reduced bladder capacity. In summary, the findings of the present study demonstrate for the first time that irradiation negatively impacts bladder contractility predominantly via the mucosal layer. Functional damage may involve structural and/or functional damage to bladder interstitial cells and remodelling involving NGF.

No description available.

No description available.

The focus of this research was to apply mathematical and computational methods for modelling and prediction of tumour volume during the course of radiotherapy. The developed tools could provide valuable information for the optimisation of radiotherapy in the future. Firstly, the feasibility of modelling tumour volume dynamics of individual patients, as measured by computed tomography (CT) imaging, was explored. The main objective was to develop a model that is adequate to describe tumour volume dynamics, and at the same time is not excessively complex as lacking support from clinical data. To this end, various modelling options were explored, and rigorous statistical methods, the Akaike information criterion (AIC) and the corrected Akaike information criterion (AICc), were used for model selection. The models were calibrated to data from two cohorts of non-small cell lung cancer patients, one treated by stereotactic ablative radiotherapy and the other by conventionally fractionated radiotherapy. The results showed that a two-population model with exponential tumour growth is the most appropriate for the data studied as judged by AIC and AICc. Secondly, this model was further equipped with a Bayesian adaption approach in order to predict individual patients’ response to radiotherapy in terms of tumour volume change during the treatment. The main idea was to start from a population-average model, which is subsequently updated, using Bayesian parameter estimation, from an individual’s tumour volume measurement. Therefore the model becomes more and more personalised and so is the prediction. The usefulness of the developed method was demonstrated on clinical data. Finally, attempt was made to link the predicted tumour volume (an important but often secondary treatment outcome indicator) to tumour control probability (one of the primary indicators of treatment outcome), and this model was demonstrated through a simulation study. Overall this research has contributed new methods and results of mathematical modelling for quantitatively analysis and prediction of individual patients’ response to radiotherapy; it represents a significant development that could be used for improved and personalised planning and scheduling of radiotherapy in the future.

No description available.

No description available.

Ultraviolet radiation (UVR) evokes a plethora of effects in skin ranging from erythema and epidermal apoptosis, to photoageing and ultimately photocarcinogenesis. UVR is also used successfully as a therapy for atopic eczema and psoriasis and both the beneficial and detrimental effects of UVR depend partly on wavelength of radiation. Understanding the signaling mechanisms activated in human skin and the wavelength specificity, may provide insight into the molecular mechanisms regulating the pathological and therapeutic actions of UVR. Nuclear factor of activated T-cells (NFAT) is a calcium/calcineurin-regulated transcription factor that resides in an inactive, phosphorylated state in the cytoplasm. Dephosphorylation of NFAT by calcineurin evokes nuclear translocation and transcriptional activation of NFAT. It is shown in this thesis that UV-induced NFAT nuclear translocation and transcriptional activation is wavelength dependent. Five different UVR sources, covering the UV spectrum, each evoked a dose-dependent increase in NFAT transcriptional activity. The action spectrum for NFAT activation was derived by mathematical induction which highlights an inverse association between wavelength and NFAT transcriptional activity. UV-induced translocation of endogenous NFAT2 and GFP-NFAT2 is also wavelength-dependent and it appears that UVR specifically activates NFAT2,in HaCaT keratinocytes. For the first time, it is also demonstrated that UVR stimulates nuclear translocation of NFAT2 in skin equivalent models and in human skin in vivo. Cyclooxygenase-2 (COX-2) is a proinflammatory, procarcinogenic enzyme that has been implicated in transmitting the procarcinogenic effects of UVR. COX-2 luciferase reporter vec~ors which lacked functional NFAT binding sites, indicate that NFAT is required for maximal induction of the COX-2 promoter by UVR. Induction of COX-2 protein in HaCaTs by UVR is reduced by inhibiting UV-induced NFAT activation by pretreating HaCaTs with cyclosporin A. Induction of COX-2 by UVR is also wavelength-dependent and this is similar to the wavelength-dependence of NFAT. UVinduced apoptosis of HaCaTs is increased by inhibiting UV-induced NFAT activation. Taken together, these data implicate NFAT as being an important regulator of UV-induced COX-2 expression and apoptosis. The procarcinogenic and antiapoptotic role played by UVactivated COX-2 may be mediated, in part, by upstream NFAT signaling. It is also demonstrated that NFAT2 regulates keratinocyte proliferation. Overexpressing GFP/ NFAT2 increased proliferation of both HaCaTs and NHEKs and knockdown of NFAT2 using siRNA, reduced proliferation of HaCaTs. NFAT transcription factors may therefore play an important role in the pathology of hyperproliferative skin disorders and may be involved in UV-induced keratinocyte proliferation. UVR is involved in the pathogenesis of malignant melanoma (MM), the most aggressive form of skin cancer, which is notoriously unresponsive to current therapies. In this thesis, it is shown that the NFAT signaling pathway is functional in melanoma cell lines. NFAT transcriptional activity is inducible and cyclosporin-sensitive and both basal and inducible activity appears to correlate positively with the presence of a B-RAF mutation, shown to be present in up to 70% of MM. Melanoma cell proliferation is reduced by inhibiting NFAT with cyclosporin A, which induces an arrest in G1 phase of the cell cycle. COX-2 is a potential prognostic marker for MM and it is shown that COX-2 promoter activity and protein expression is regulated by NFAT. NFAT may be an important mediator of proliferation and invasion of melanoma via the induction of COX-2. Further studies are warranted to assess whether NFAT represents a novel therapeutic target for treatment of MM.

The use of traditional and complementary medicines (T&CMs) is both ubiquitous in low and middle income countries and highly contested in some sections of high income countries. Whilst T&CMs are promoted as an accessible and affordable health care system by high level health policy makers (for example, the Director General of the World Health Organization), their use is simultaneously indicted as a waste of resources, non-scientific, and unethical. The aim of this thesis is to provide a calm, considered and well researched view on a highly emotional topic: What is the nature of the ethical challenges for the use and practice of TCMs and how might they be addressed? The methodology chosen for the ambitious topic of this thesis is the Ethical Matrix as developed by Ben Mepham in the UK in the 1990s. It is founded upon a principlist approach to ethical analysis and has been used widely in decision-making for new technologies. It requires the consideration of interests of stakeholders including, but also beyond, human beings. For the purpose of this thesis four groups were selected: human users of T&CM, the environment, animals, and low and middle income countries (LMICs). Ethical analysis reveals that: • Most ethical concerns associated with T&CMs are related to safety issues for human users; • there are also serious concerns about the way in which animals are routinely harmed through use in T&CM products and T&CM research; • the production and use of some T&CMs does have damaging impacts upon the environment and, • the ethical challenges associated with the use of T&CM in LMICs are different from those in high income countries. Based on the analysis, the thesis provides clear steps to be taken to reduce the potential for harm from both adverse drug reactions and adverse events for humans as well as recommendations to reduce the harm to animals and the environment from use of T&CMs.