Upper gastrointestinal tract cancers originating from oesophagus, oesophago-gastric junction or stomach constitute a major health problem around the world as well as in UK. Chapter 1 of the thesis describes the incidence, mortality, aetiology, staging, treatment and outcome of patients with oesophageal and gastric cancer. Each year approximately 8,000 people are diagnosed with oesophageal cancer and a similar number of people diagnosed with gastric cancer in UK. Early detection and surgery confers the greatest chance of long-term cure in oesophageal and gastric cancer. However, upper GI cancer surgery is associated with considerable morbidity and mortality. Postoperative mortality following gastro-oesophageal cancer resection is significant and has been reported as varying from 1%–23%. Therefore, preoperative surgical risk assessment is a vital part of modern surgical practice. Pathological TNM staging by American Joint Committee on Cancer (AJCC) is an established factor in predicting long term survival following resection of oesophageal and gastric cancer. However, it is increasingly recognised that, not only the intrinsic properties of tumour cells determine tumour spread but also the host inflammatory response has a vital role. Indeed, the systemic inflammatory response, as evidenced by elevated circulating concentrations of C-reactive protein, prior to surgery, has previously been shown to have independent prognostic value in patients with resectable gastro-oesophageal cancer. The overall aim of the thesis was to examine the inter-relationships between patient physiology, local and systemic inflammatory response and outcome (both short and long term), in patients undergoing resection for oesophageal and gastric cancer. Chapter 2 compared the POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) and mGPS (modified Glasgow prognostic score) models in prediction of post-operative outcome, both short and long term, in 121 patients undergoing resection of oesophago-gastric cancer. The results in this chapter demonstrated that, the POSSUM physiological score was an independent predictor of post-operative complications. On the other hand, elevated systemic inflammatory response as evidenced by the mGPS and not, patient physiology or post-operative complications, was independently associated with poor cancer specific survival. Therefore, results of the present study suggested that, pre-operative host related factors were important in determining both short and long term outcome following potentially curative resection of oesophago-gastric cancer. Chapter 3 examined the value of serial daily post-operative markers of systemic inflammatory response such as white cell count, albumin and C-reactive protein concentrations in the prediction of post-operative infectious complications in 136 patients following resection of oesophago-gastric cancer. The results showed that the magnitude of the systemic inflammatory response, in particular C reactive protein, following resection of oesophago-gastric cancer was associated with the development of post operative complications, in particular surgical site infections and anastomotic leak. Furthermore, C reactive protein threshold of 180mg/l on post operative days 3 and 4 was shown to predict surgical site infection and anastomotic leak with good and very good diagnostic accuracy respectively. Chapter 4 compared the prognostic value of selected markers of systemic inflammatory response such as white cell count, neutrophil count, lymphocyte count, neutrophil-lymphocyte ratio (NLR), platelet- lymphocyte ratio (PLR) and mGPS in 112 patients undergoing potentially curative resection of oesophageal cancer. The result demonstrated that, only mGPS was significantly associated with cancer specific survival and had prognostic value independent of pathological TNM stage. Therefore, an acute-phase protein-based prognostic score, the mGPS, was established to have the superior predictive value, compared to cellular components of the systemic inflammatory response in predicting survival in oesophageal cancer. Chapter 5 compared the prognostic value of selected markers of systemic inflammatory response such as white cell count, neutrophil count, lymphocyte count, neutrophil-lymphocyte ratio (NLR), platelet- lymphocyte ratio (PLR) and mGPS in 120 patients undergoing potentially curative resection of gastric cancer. The result showed that, only mGPS was significantly associated with cancer specific survival and had prognostic value independent of pathological TNM stage. Therefore, an acute-phase protein-based prognostic score, the mGPS, was established to have the superior predictive value, compared to cellular components of the systemic inflammatory response in predicting survival in gastric cancer. Chapter 6 examined the relationship between tumour necrosis, tumour proliferation, local and systemic inflammatory response, microvessel density and survival in 98 patients undergoing potentially curative resection of oesophageal adenocarcinoma. The results suggested that, among the tissue based factors, tumour macrophage infiltration appeared to play a central role in the proliferative activity and coordination of the inflammatory cell infiltrate and was also independently associated with poor outcome in patients with oesophageal adenocarcinoma. There was no direct relationship between local and systemic inflammatory response, tumour necrosis and angiogenesis; suggesting that the mechanisms underlying the relationship between local and systemic inflammatory responses and cancer-specific survival are likely to be complex. Chapter 7 examined the relationship between tumour necrosis, tumour proliferation, local and systemic inflammation, microvessel density and survival in 104 patients undergoing potentially curative resection of gastric cancer. The results suggested that, local peritumoural inflammatory infiltrate and intra tumoural necrosis appeared to play a role in tumour proliferation and poor outcome in patients with gastric cancer. There was no direct relationship between local and systemic inflammatory responses, tumour necrosis and angiogenesis; suggesting that the mechanisms underlying the relationship between local and systemic inflammatory responses and cancer-specific survival are likely to be complex. In summary, preoperative patient’s physiological status (as measured by POSSUM model) has been shown to be a good predictor of short term outcome i.e. postoperative morbidity and mortality following resection of oesophago-gastric cancer. Moreover postoperative serial measurements of C-reactive protein have been shown to be a useful tool to predict infectious complications. An elevated systemic inflammatory response (as evidenced by the mGPS) preoperatively has been established to be a predictor of poor survival, independent of tumour stage in both oesophageal and gastric cancer. Therefore, these results suggest that measurement of the mGPS should be performed routinely as part of preoperative clinical staging, to improve stratification of patients and therefore enable clinicians to optimise the treatment of patients with oesophageal and gastric cancer.

Diabetes mellitus is a worldwide health issue. It is a major and growing cause of morbidity and mortality. Rates of end-organ damage are increasing proportionately, as are the associated personal, societal and economic costs. Diabetic foot ulceration is responsible for a significant proportion of this. The development of diabetic foot ulceration is complex with multiple injurious processes potentially affecting a foot at any time. Defining the significance of ischaemia as a consequence of peripheral arterial occlusive disease can be difficult and identifying which patients may benefit from revascularisation in terms of reversing of the natural history of the disease process remains poorly understood. The utility of the University of Texas classification to identify patients at highest risk of major adverse clinical events has been explored from 971 ulcer episodes affecting 515 limbs (388 patients). Peripheral arterial occlusive disease was identified in 44.6%. These patients had a significantly higher risk of major amputation than patients without peripheral arterial occlusive disease (13.5 versus 4%). University of Texas scoring would appear to robustly identify patients at highest risk of major adverse clinical events. The potential usefulness of Connexin 43 and its phosphorylated isoform Connexin 43(Serine368) as biological markers of ischaemia in skin have been explored. Immunohistochemistry provided qualitative data demonstrating up regulation of Connexin 43(Serine368) in skin biopsies from ischaemic feet – this is a novel finding. Connexin 43 (Serine368) was not identified in any of the controls nor in proximal skin biopsies of patients with peripheral arterial occlusive disease. Connexin 43 expression did not appear to be modified. When human fibroblasts and keratinocytes were subjected to hypoxic conditions (1% oxygen/4% carbon dioxide/nitrogen) in vitro, both Connexin 43 and Connexin 43(Serine368) were up regulated with protein expression peaking between 12 to 24 and 6 to 12 hours respectively. Peptidoglycan challenge appeared to up-regulate the expression of Connexin 43 protein, but did not influence the expression of Connexin 43(Serine368). These data suggest that Connexin 43(Serine 368) may have potential utility as a biological marker of ischaemia in human skin.

Severe thermal injury results in a profound hypermetabolic response and is associated with increased morbidity, mortality and delayed rehabilitation of burn survivors. Serum 1H-NMR metabolomics was used to examine early global metabolic changes in the response to severe thermal injury (>15% TBSA) in young adults (16-64 years) and older adults (< 15% TBSA). Early changes in the metabolome reflected hypoxic metabolism, hyperglycaemia, increased ketogenesis, peripheral lipolysis and increased energy production in both cohorts. Early metabolic profiles from the young adult group were used to construct OPLSDA models that could discriminate with high accuracy between outcome groups. Models from 0-24hrs serum samples predicted survival (AUC 0.92), whilst models from 24-96hrs samples predicted Multiple organ failure (MOF) (AUC 0.92) and sepsis (AUC 0.89). Untargeted LC-MS metabolomics was applied to study the longitudinal changes in the serum metabolome after severe thermal injury in 13 young adults, from admission until 6-months post-injury. Univariate ANOVA analysis revealed significant changes in 432 metabolite features, affecting 35 distinct classes, representing global metabolic disturbance. Changes in 300 lipid metabolite features may represent a ‘lipid storm’ in serum after severe thermal injury. Novel areas of metabolism and metabolites were identified as putative biomarkers warranting further targeted study.

End stage liver disease represents a common end point for a number of disease processes, the only current treatment for which is liver transplantation, but the demand for donor organs exceeds the supply. This has led to the use of more marginal donors with an increase in the rates of complications. Mesenchymal stem/stromal cells (MSC) are a multipotent cell capable of modulating the immune system through a number of different processes and represent a potential therapy in post transplantation liver injury. In this study I describe the prospective isolation and culture expansion of murine MSC. In in vitro assays MSC suppressed T lymphocytes and following stimulus with inflammatory cytokines MSC secreted a number of cytokines including Il-10. In the MDR2-/- model intravenous MSC therapy led to a reduction in liver injury with an increase in restorative macrophages. Subcutaneous administration of MSC showed no beneficial effect. MSC were also tested in a hepatic ischaemia reperfusion injury model where no effect was seen. In summary MSC were able to suppress lymphocyte proliferation and secrete anti-inflammatory cytokines in vitro, and in vivo they were able to reduce liver injury in the MDR2-/- model but not the hepatic ischaemia reperfusion injury mode.

Approximately 10-20% of human colorectal cancers harbour an activating BRAFV600E mutation, which acts as a founder mutation for an alternative, serrated pathway of colorectal carcinogenesis. Conversely, BRAFV600E mutations are detectable in hyperplastic colonic polyps: lesions traditionally considered not to harbour malignant potential. Furthermore, both in vitro and in vivo, activated oncogenic BRAFV600E induces a stable proliferation arrest: oncogene induced senescence, which is a fundamental intrinsic tumour-suppressor mechanism. Thus, for neoplastic transformation to occur, it is clear that additional genetic and epigenetic events are required. BRAFV600E-mutant colorectal cancers are frequently associated with a CpG island methylator phenotype (CIMP), which is proposed to promote neoplastic transformation by bypass of intrinsic tumour-suppressor mechanisms, such as silencing of CDKN2A/INK4A. Consistent with this, neoplastic transformation in the serrated pathway is characterised by the progressive development of a CIMP phenotype. An emerging body of evidence supports a model in which the BRAFV600E mutation directly induces CIMP through the de novo methyltransferase, DNMT3B. Separately, elevated DNMT3B expression has previously been linked to the development of CIMP in both murine and human colorectal cancer. The published data however do not universally support this model, and significant questions over its validity remain. In the present work, the relationships between BRAFV600E mutation, DNMT3B expression and the CpG island methylator phenotype were examined by multiple approaches. A panel of DNMT3B antibodies were first characterised and validated. Significantly, the antibody previously used to link DNMT3B and CIMP in human colon cancer was demonstrated not to react with human DNMT3B. The ability of BRAFV600E to induce CIMP was next tested by whole genome bisulfite sequencing in a primary cell culture model. Surprisingly, activated BRAFV600E repressed expression of DNMT3B and failed to induce a CIMP phenotype. Consistent with this, human colorectal cancer cell lines expressing activated BRAFV600E typically expressed a low level of DNMT3B, and inactivation of DNMT3B in a BRAFV600E-mutant, CIMP-positive cell line did not reverse gene silencing characteristic of CIMP. An in vitro model system was next designed to test functional interactions between BRAFV600E and DNMT3B. Ectopic expression of DNMT3B antagonised BRAFV600E-induced proliferation arrest: a hallmark of senescence. Moreover, ectopic DNMT3B expression was demonstrated to accelerate BrafV600E-induced intestinal carcinogenesis in a mouse model, and conversely, Dnmt3b knockout impaired BrafV600E-induced murine intestinal carcinogenesis. Analysis of human colorectal cancer TCGA data was next undertaken, and confirmed that expression of DNMT3B is frequently elevated in human colorectal cancer and that this is often linked to amplification of the DNMT3B gene. However, more detailed analysis of human TCGA data revealed that BRAFV600E mutation is neither necessary nor sufficient to induce CIMP, and that both BRAFV600E mutations and CIMP are both linked to low expression of DNMT3B. Thus, while both BRAFV600E and DNMT3B both harbour oncogenic potential, they do not appear to cooperate to induce CIMP, and do not appear to cooperate frequently in human colorectal cancer by any mechanism.

Intravascular stents of various designs are currently used to prop open diseased arteries and there is evidence that different stent geometries have different in-stent restenosis rates. The majority of commercially available stents are designed generically to fit all individuals. Recent advances in imaging and catheter technologies, however, allow measurement of lesion shape and stiffness. Incorporating patient specific data into the stent design process could enable the development of customised stents. Considering the variety of lesion types, it is envisaged that better outcomes will be achieved if a stent is custom designed in such a way that it has variable radial stiffness longitudinally to hold the varying pressure of plaque and healthy artery at the same time while maintaining an acceptable lumen diameter. This type of operation is suitable for topology optimisation potentially allowing for optimal material distribution of a stent. The primary aim of this research is to develop new stent designs for a set of plaque types and investigate the final radius of the lumen after stent implantation. Stent geometries were obtained by topology optimisation for minimised compliance under different stenosis levels and plaque materials. Three types of stenosis levels by area, i.e. 30%, 40% and 50% with each type having three different plaque material properties i.e. calcified, cellular and hypocellular were studied. The optimisation results were transformed to clear design concepts and their performance was evaluated by implanting them in their respective stenosed artery types using finite element analysis. The results were compared with a generic stent in similar arteries, which showed that the new designs showed less recoil. In the hardest (calcified) of plaques studied, topology optimised designs overall resulted in 2%, 2% and 6% residual area stenosis compared to 10%, 29% and 35% from the generic design in arteries with 30%, 40% and 50% stenosis respectively. It was shown that higher material distribution resulted in the central region of the stent in order to resist implantation recoil due to higher plaque compressive loads. Additive manufacturing (AM) was utilised to validate the computational approach used in this thesis. This work provides a proof of concept for stents tailored to specific lesions in order to minimise recoil and maintain a patent lumen in stenotic arteries.

This thesis presents a range of novel mono and di-substituted hydroxyapatite powders, characterised by a range of techniques to ascertain their chemical composition, crystallographic composition, physical properties, and in vitro bioactivity. The novel compositions consist of substituting a range of Borate, Sulphate, Silicate, and Strontium in levels ranging from 1.5 mol.%, up to 5 mol.%. It was found that a 4 mol.% inclusion of 2 mol.% Sr2+ and 2 mol.% SO42- gave a significant increase in the amount of osteocalcin produced and may represent an improved biomaterial warranting further study.

Back muscle weakness and lower back pain affect the quality of life and productivity at work, and such age-related problems are prevalent among middle-aged and elderly people. Wearable exoskeletons/soft suits offer substantial promise as a means to augment strength, assist movement and improve stability of the human body. This thesis presents the design, modelling and evaluation of a novel soft suit (“Active-Vest”) for human back support. Active-Vest is human-friendly, flexible, lightweight and able to reduce the efforts of back muscles and reaction forces at the lumbar spine joints during flexion-flexion motions of the back in the sagittal plane. The design of the Active-Vest allows the support of the back without involving the lower limbs, meaning it may provide a better walking experience. The assistance capabilities and safe application of the vest design were assessed in OpenSim software employing a series of biomechanical models of the proposed vest united with an enhanced human musculoskeletal model assembly. The simulation revealed that the soft actuator system reduced the erector spinae muscle force required to articulate the back during flexion-extension motions in the sagittal plane by 60%. Simultaneously, the maximum compression and shearing forces acting on the lumbosacral and L1-L2 joints were reduced by 39% and 32% respectively, as the vest actuators act on a larger lever arm than the corresponding muscles. The Active-Vest prototype has been fabricated and laboratory evaluations on a healthy subject have been performed to quantify human-vest interaction. Evaluations confirmed that wearing the vest reduced the magnitude of the surface Electromyography signal (EMG) of erector spinae muscles by 61% during said flexion-extension motions in the sagittal plane, supporting the prediction of the computer simulations of reduced erector spinae muscle activity and reduced reaction force at lumbar joints. Further, the prototype reduced the EMG signal by 43% to maintain the trunk status in the transverse plane against gravity. These results demonstrate the practicability and promise of Active-Vest to aid people with reduced back strength and to decrease lower back pain and risk of back injury. Considering these promising results, the methods proposed in this work contribute towards a more human-back assistance/lower back pain/injury risk reduction. In future, the vest will be able to involve the aid of all spinal range of motions and present the feasibility of wide-community utilization. Future work will increase the number of actuators of the Active-Vest and the vest could be expanded to a full body suit.

In this project innovative manufacturing processes have been developed and characterised for the efficient and effective fabrication of PGF-PLA composites which have adequate properties for the fixation of fractured bones in flat and curved geometries. Fully bioresorbable composite plates where produced by compression moulding of unidirectional phosphate glass fibre mats and PLA films alternatively stacked inside the mould cavity. The implementation of cyclic pressure during the compression moulding consolidation stage resulted in the production the strongest PGF-PLA composites hitherto reported. The strength of the composites consolidated via cyclic pressure was at least 30% higher with respect to the control samples fabricated using the conventional static pressure profile, reaching values of 480 MPa for plates reinforced with 0.45 fibre volume fraction. The increases in composite strength were attributed to the influence of pressure cycling on the fibre network permeability, melt viscosity and capillary pressure, leading to improved fibre impregnation with respect to statically applied pressure, obviating the need for elevated processing temperatures to reduce the melt viscosity. Pressure cycling seemed to promote the formation of transcrystalline layer around the fibres which could have also contributed to the superior properties of composites consolidated under cyclic pressure. PGF-PLA composite rods with cylindrical cross sections were manufactured via uniaxial compression and plane strain forging of preconsolidated composite blanks obtained from compression moulded composite plates. Forging under uniaxial conditions reduced both the flexural strength and the elastic modulus of all the composite rods in comparison to the compression moulded composite plates by as much as 85% and 47%, respectively, for the 0.35vf samples consolidated under cyclic pressure, as a result of the fracture of the fibres consequent to the extensional flow. Fibre fracture was prevented through confinement of the deformation to the x-y plane during plane strain forging. The mechanical properties of the compression moulded composite plates were preserved in the forged composite rods with 0.15 and 0.25 fibre volume fractions, but the high segregation of fibres in the 0.35vf and 0.45vf compression moulded composite plates fabricated with thick glass fibre mats led to the reduction of both the flexural strength and modulus of the forged composite rods with respect to the compression moulded composite plates by as much as 74% and 29%, respectively, for the 0.45vf consolidated under cyclic pressure, as a result of the nucleation of intra-ply cracks during plane strain forging. The deleterious effect of intra-ply cracks in the plane strain forged composite rods was significantly reduced by stacking a larger number of thinner phosphate glass fibre mats prior to compression moulding of the 0.35vf and 0.45vf composite plates. The properties of the forged composite rods decreased in aqueous media. The initial loss of strength and modulus was attributed to the water-mediated lubrication of the fibre-matrix interface. Further decreases in mechanical properties were related to the fibre diameter reduction as a result of quick glass dissolution, which impaired the frictional stress transfer. Complete loss of the reinforcing effect of glass fibres was observed after 15 days of immersion in aqueous media. Cylindrical PGF-PLA composite rods were also produced via a new and leaner manufacturing method consisting in compression moulding of thermoplastic hybrid preforms. Hybrid preforms were produced by depositing a sheath of PLA on phosphate glass fibre bundles continuously fed into a cross head extrusion die. Due to the characteristics of the technique, composites could be reinforced with both as-drawn and annealed phosphate glass fibres which were embrittled as a result of anisotropy relaxation and the formation of a surface tensile layer following heat treatment. On account of the effect of annealing on the phosphate glass fibres mechanical properties, the flexural strength of as-drawn fibre reinforced compression moulded composite rods was higher with respect to annealed fibre reinforced ones, the former reaching maximum strength values of 371 MPa for the 0.45vf samples in comparison to 278 MPa for the latter. The flexural moduli of the composites rods manufactured through consolidation of PLA-sheathed fibre bundles were the highest hitherto reported for bioresorbable composites reaching values in excess of 30 GPa for the samples with 0.45vf. The higher modulus values of this type of rods with respect to conventional laminated composites were associated with their unique reinforcement distribution achievable by compression moulding of PLA-sheathed fibre bundles. Annealed fibre reinforced composites showed a better retention of mechanical properties in wet conditions with respect to as-drawn fibre reinforced ones, as a result of the slow degradation of annealed fibres, managing to present values even exceeding the human cortical bone range during the 30 day in vitro degradation study.

Background: Burn injuries disproportionally affect the world’s poorest regions. However, there is a lack of data from these areas to determine the true extent of this public health problem. Children in Malawi are at high risk of burn injuries and poor health because of the nature of their environment, and the paucity of burn prevention programmes. At present, the research that reflects the factors associated with these injuries has been limited to the interpretation of quantitative, hospital based data, which may provide patterns of burns risks, but does not reflect the context or perception of burn injuries necessary to create culturally appropriate and targeted prevention initiatives. Moreover, while it has been suggested that the use of improved cookstoves (ICS) in these areas might mitigate children’s exposure to burn injuries more research is needed. Aim: To explore the factors associated with paediatric burn injuries in rural and peri-urban Malawi. Methods: This study employed a qualitative approach to explore the contextual factors, associated with paediatric burn injuries, across four villages in Malawi. Three of these villages had been previously exposed to an ICS intervention. In addition to conducting observations of household environments, multiple perspectives of burn injuries were sought from 32 parents, 12 health professionals and 6 key stakeholders using semi-structured interviews. Focus groups were conducted with household participants to gain a better understanding of safety in relation to their cooking methods. The data obtained were analysed using thematic analysis. Results: The study revealed a number of environmental and social factors which put children at risk of burn injuries across rural and peri-urban Malawi. Parents are often limited in their ability to provide adequate protection against such injuries because of: a lack of knowledge about injury prevention, a lack of safety equipment, a lack of control to make alterations to their housing and an inability to adequately supervise children. Additionally, health professionals reported that, due to a lack of time and resources, they were unable to consistently provide information to parents and caregivers about preventing burn injuries in the home. Those working with existing ICS initiatives in Malawi revealed that, although kitchen safety is currently discussed as part of organisations’ promotional activities, there is a lack of data measuring the effectiveness of this teaching. Conclusion: The factors associated with paediatric burn injuries and prevention, both actual and perceptual, are multifaceted and intertwined with the complex nature of the household environment and those who live within it. This study has provided a starting point from which to understand these factors and gives a voice to those affected. Overall the results demonstrate that there is an urgent need to raise an awareness of the burns problem to policy makers, key stakeholders, health professionals and parents, to initiate the development of comprehensive prevention initiatives. Future strategies need to consider the integration of multilevel support to address the challenges faced by families living in rural and peri-urban Malawi.