Familial Hypercholesterolaemia (FH) is an autosomal dominant disorder with a frequency of 1 in 250 to 500 in most European populations. It is characterised by a raised low density lipoprotein-cholesterol (LDL-C) and a high incidence of premature coronary heart disease (CHD). There are three genes where mutations are known to cause FH: the low-density lipoprotein receptor (LDLR) gene, the apolipoprotein B (APOB) gene and the pro-protein convertase subtilisin/kexin type 9 (PCSK9) gene. An FH-causing mutation can be found in around 40% of patients with a possible diagnosis of FH. It has been suggested that the patients with a clinical diagnosis of FH where no mutation were found might have a polygenic cause for their raised LDL-C. FH disorder is an under-diagnosed condition in many countries such as Poland. An analysis of a Polish FH cohort in this thesis, demonstrated the heterogeneous aetiology of FH. We found 39 different pathogenic mutations in the LDLR gene with 10 of them being novel and an overall detection rate of 43.4%. The aim of this thesis was to compare preclinical atherosclerosis between patients with monogenic FH and subjects with polygenic hypercholesterolaemia by means of a neck ultrasound to measure carotid Intima Media Thickness and a cardiac CT scan to assess coronary artery calcification. This study showed that preclinical atherosclerosis was greater in patients with monogenic FH. Lipoprotein(a) [Lp(a)] is a well-known biomarker for CHD risk prediction. The Lp(a) concentration and its association with two LPA single nucleotide polymorphisms (rs3798220 and rs6919346) were assessed in FH patients participating in the Simon Broome registry and a group of the general population participating in the Northwick Park Heart Study II. The results showed that the Lp(a) concentration and the frequency of rs3798220 was significantly higher in the FH patients compared to the general population.

Independent mobility is fundamental to the quality of life of people with impairment. Most people with severe mobility impairments, whether congenital, e.g., from cerebral palsy, or acquired, e.g., from spinal cord injury, are prescribed a wheelchair. A small yet significant number of people are unable to use a typical powered wheelchair controlled with a joystick. Instead, some of these people require alternative interfaces such as a head- array or Sip/Puff switch to drive their powered wheelchairs. However, these alternative interfaces do not work for everyone and often cause frustration, fatigue and collisions. This thesis develops a novel technique to help improve the usability of some of these alternative interfaces, in particular, the head-array and Sip/Puff switch. Control is shared between a powered wheelchair user, using an alternative interface and a pow- ered wheelchair fitted with sensors. This shared control then produces a resulting motion that is close to what the user desires to do but a motion that is also safe. A path planning algorithm on the wheelchair is implemented using techniques in mo- bile robotics. Afterwards, the output of the path planning algorithm and the user's com- mand are both modelled as random variables. These random variables are then blended in a joint probability distribution where the final velocity to the wheelchair is the one that maximises the joint probability distribution. The performance of the probabilistic approach to blending the user's inputs with the output of a path planner, is benchmarked against the most common form of shared control called linear blending. The benchmarking consists of several experiments with end users both in a simulated world and in the real-world. The thesis concludes that probabilistic shared control provides safer motion compared with the traditional shared control for difficult tasks and hard-to-use interfaces.

Rotator cuff (RC) injuries are among the most common upper limb injuries, causing impaired function and pain for patients, as well as resulting in a significant financial burden for health care providers. Chronic RC tears are associated with tendon retraction from the bone surface making their surgical repairs challenging. In order to enhance the outcome of these surgeries, different grafts have been investigated however, these do not restore the biological and functional properties of the native enthesis. This study aims to investigate the use of demineralised bone matrix (DBM) with cells as an augmentation strategy for enhancing regeneration of the tendon-bone enthesis. Sources of allogeneic and xenogenic DBM as potential graft materials for RC repair were selected based on their mechanical strength. The effect of DBM and extracts of DBM on differentiation of stem cells and trans-differentiation of tenocytes and osteoblasts was investigated. This study showed that DBM was able to induce differentiation of MSCs and trans-differentiation of tenocytes and osteoblasts into chondrocytes. Using both allogeneic and xenogenic grafts together with stem cells isolated at the time of surgery in an ovine in-vivo model of patellar tendon avulsion allogenic DBM was able to recapitulate the natural enthesis and led to near normal function 12 weeks after surgery. The repair process with xenogenic grafts was slower and there were differences in both the functional recovery and in the morphology of the enthesis when xenogenic grafts were use. It was concluded that DBM has sufficient mechanical and biological properties, which in combination with MSC augmentation can enhance healing of the tendon-bone enthesis.

Barrett's oesophagus is the most important risk factor for the development of oesophageal adenocarcinoma (OA), but progression is unpredictable. Dysplasia predicts which Barrett's patients are at greatest risk for OA but achieving the diagnosis can be challenging. Immunohistochemistry with p53 is recommended as an adjunct to assist with dysplasia diagnosis. This thesis will examine if replication licensing factors and DNA ploidy status are as good if not better than p53 to assist in the diagnosis of dysplasia. Overexpression of HER2 in foregut cancer is an indication for HER2 targeted treatments. Its influence on prognosis is less understood. The relationships between clinicopathological variables, HER2 overexpression and prognosis will next be evaluated. Current ablative techniques for Barrett's neoplasia are limited to superficial disease. Photodynamic therapy was a treatment for Barrett's that could penetrate more deeply into diseased tissue but was limited by the side effects of off-target photosensitivity. Combining targeting vehicles such as antibodies to newer and more deeply penetrating photosensitiser drugs, may overcome the previous limitations of this technology. A photosensitive ADC against HER2 will be created and its efficacy in vitro and in vivo evaluated. However, even the most effective ADC against HER2 will not treat the majority of cancers, as we will show HER2 is only expressed in the minority of foregut tumours. The final experiments will look to characterise the mucin MUC1 in Barrett's and associated neoplasia. Studies have previously shown it to be present in up to 100% of cancers while others say far fewer. We will show proof of principle data for the development of a MUC1 targeting photosensitive ADC in vitro and postulate how it may in future enable treatment of locoregional invasive tumours endoscopically.

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Introduction: Rupture of the anterior cruciate ligament (ACL) of the knee is a common injury among athletes, leading to instability of the knee. Due to the poor healing capacity of this ligament, reconstruction is currently the only suitable method of treatment. At present, material for reconstruction is most often harvested from the donor’s patellar tendon, which can lead to issues with donor site morbidity and further knee instability. This has led to the development of synthetic ligaments, which have demonstrated varying levels of success. Xiros Ltd. (Leeds) have developed a woven polyethylene terephthalate (PET) ligament prosthesis able to induce tissue formation in vivo. However, tissue induction is slow, leaving the material exposed to abrasive forces upon implantation, which eventually leads to graft failure. Objective: To assess whether a hybrid construct, composed of the Xiros PET ligament and a platelet-rich biopolymer coating, can enhance synovial cell proliferation, infiltration and expression of extracellular matrix genes, which may indicate promotion of tissue induction. Methods: Primary bovine synovial cell (bSC) cultures were established from the metatarsophalangeal joints of 12-18 month old bovines. Venous blood was taken from healthy human donors and platelet-rich and platelet-poor plasma fractions were extracted. 3D cell-seeded hybrid ligament constructs were fabricated by seeding bSCs onto sections of Xiros Ltd. PET scaffold before coating them with various combinations of plasma, collagen and alginate. Cells were monitored within coated constructs using confocal microscopy, DNA content analysis and Live/dead staining. Biopolymers were characterised using scanning electron microscopy (SEM) and rheology. Coating longevity was assessed using light microscopy image analysis. Cyclic tensile strain (5% strain at a frequency of 1 Hz) was applied to the three most promising coated constructs using an in-house house developed bioreactor, and qRT-PCR was used to measure changes in expression of ligament and non-ligament associated genes. The effect of cyclic tensile strain on tPA and PAI-1 gene expression was analysed using qRT-PCR and secreted PAI-1 protein was assessed using Western blot. Results: Alginate-based coatings demonstrated the greatest stability, but significantly inhibited cell infiltration and proliferation. In contrast both plasma and collagen coatings had poor longevity, but promoted cell infiltration, in comparison with the non-coated control scaffold. All constructs supported good cell viability. PDGF-AB and IGF-1 release from coatings occurred up to 3 days. Changes in expression of ECM and transcription factor genes were inconsistent between donors. Cyclic tensile strain increased cell proliferation in all constructs. The longevity of the 100% plasma (P100) coating was greatly enhanced by the application of cyclic tensile strain, leading to selection of this construct for final studies. Strain induced no change in tPA gene expression but caused a significant upregulation of PAI-1 gene expression and protein secretion, indicating a possible mechanism of enhanced coating longevity. Increasing the platelet density of the P100 coating had no significant effect on cell proliferation nor transcription of ECM genes. Discussion: This study has demonstrated that bovine synovial cell-seeded 3D hybrid ligament constructs composed of the Xiros Ltd. PET scaffold and a biopolymer coating, can be successfully fabricated, and are compatible with the cyclic strain bioreactor utilised for this work. The 100% plasma-coated construct was the most successful candidate due to its ability to promote cellular infiltration, as well as its superior longevity when subjected to cyclic tensile strain. Application of cyclic tensile strain to cell-seeded constructs resulted in upregulation of PAI-1, which may have contributed to this increase in coating longevity. Conclusion: These findings demonstrate the potential of a PET-fibrin construct for ligament regeneration purposes, and indicate the importance of regular exercise of the knee immediately following ACL reconstruction. Further studies should focus on the behaviour of this construct in vivo.

In the last two decades, zirconia has been of a great interest to dentists due to its superb mechanical and optical properties. At first, the use of zirconia was limited to fabrication of cores replacing the metal in crown construction. Nowadays, there is an increase in the trend of using monolithic ‘full contour’ translucent zirconia to overcome the problem of chipping of porcelain veneers and to overcome the limitation of using lithium disilicate in long span replacement. This has brought zirconia in direct contact with saliva and oral fluids and introduced the possibility of the material undergoing low temperature degradation. This study aimed to investigate the effect of accelerated hydrothermal aging on the mechanical and optical properties of two conventional core and two full contour translucent zirconia materials, expected to be used by 90% of zirconia manufacturers globally. Hydrothermal aging was carried out using an autoclave to simulate in vivo aging, using a specific protocol proposed by ISO 13356:2015 mimicking 15- 20 years of clinical service of the material. Each of the four materials were tested before and after aging, including structural analysis which was carried out using XRD, SEM, FIB-SEM and AFM. Mechanical property investigations were carried out by measuring BFS and Vickers hardness. Optical properties were thoroughly investigated through measuring a range of translucency parameters and changes in colour before and after aging. The results of this study showed that conventional core materials were less affected by hydrothermal aging in comparison to full contour translucent zirconia in terms of optical properties. All of the used materials showed clear colour changes after aging, however none of them showed significant changes in the mechanical properties even with more than 20% of t →m phase transformation in one of the translucent zirconia materials. Within the limitation of this in vitro study, it can be concluded that full contour translucent zirconia can be used clinically with no concern about its mechanical and optical properties, however, further studies on the perception and acceptability for changes in the optical properties would be highly recommended.

Objective: To use a novel nanocomposite polymer based on polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane with superior bio-mimetic properties in the development of endovascular stent-grafts. Methods: A self-expanding and sutureless aortic stent-graft was developed using nanocomposite polymer bonded to Nitinol. A new aortic model was designed for physiological assessment of stent-grafts and compliance and viscoelasticity were measured and compared with porcine aortas as control. The stent-grafts (n=4) were fatigue tested using in vitro accelerated model for 400-million cycles equivalent to 10-years in human body and compared with zero-cycled control. A curved and conformable stent-graft was developed for thoracic aorta and aortic arch. Compliance and stiffness index of the thoracic stent-graft were measured in vitro and compared to FDA-approved Gore TagTM stent-graft based on ePTFE (expanded polytetrafluoroethylene). MRI compatibility of the thoracic stent-graft was assessed by analysing signal attenuation and velocity measurements (flux) and compared to FDA-approved Medtronic ValiantTM. Results: The stent-graft had expanded diameter of 31.1 mm and was successfully collapsed to 6.5 mm to achieve delivery profile similar to current devices. The thoracic stent-graft had uniform graft thickness of 150.7±6.6 μg and conformed to the curvature of aortic arch. The new aortic model was significantly more compliant than porcine aortas with no significant difference in elastic stiffness. All the stent-grafts successfully completed accelerated pulsatile fatigue testing. Scanning electron microscopy images confirmed uniform surface topography. There was no loss of tensile strength, or compliance and no evidence of thermo-mechanical degradation in the nanocomposite polymer. Compliance of the thoracic stent-graft was significantly better compared with ePTFE stent-graft (3.3±0.61 vs. 2.3±0.95 %/mm Hg x 10-2; P=0.0003). On MRI, there was no significant signal attenuation and no significant difference in flux between Valiant and nanocomposite polymer stent-grafts (102±2.27 vs. 99.8±2.4 ml/sec; P=0.33). Conclusions: A new endovascular stent-graft based on novel design and nanocomposite polymer with properties of compliance, viscoelasticity, anti-thrombogenicity and MRI compatibility has been developed. Sutureless technology with new biocompatible material bonded to Nitinol stents proved to be robust with no separation over accelerated 10-year cycle. These stent-grafts have the potential to address poor long-term durability, thrombogenicity, and compliance mismatch associated with present generation devices and reduce reintervention rate.

Menstruation is the leading cause of iron deficiency anaemia in pre-menopausal women. When combined with regular exercise, iron deficiency (ID) risk in menstruating women is increased. This may be exacerbated in those with heavy menstrual bleeding (HMB), which despite no validated diagnosis, is thought common in the general population but is under-investigated in exercisers. Accordingly, the potential relationship between menstruation, ID and performance remains unknown. The aims of this research were to: a) identify HMB prevalence (utilising a diagnostic series) and association with fatigue and perceived disruption to exercise training/performance in exercising women; b) evaluate the impact and existing diagnosis of ID. A ‘Female Health Questionnaire’ was developed to identify HMB amongst other factors in an exercising population (n=789), elite athletes (n=90) and London Marathon runners (n=1073). The relationships between iron status, HMB and fatigue or the perception that the menstrual cycle disrupts exercise training/performance was then investigated in exercising women (n=271). Finally, a clinical trial assessed the impact of intravenous iron repletion (single dose of 20 mg·kg-1) on exercise and aerobic capacity, haematological markers, fatigue and mood disturbance in non-elite, iron deficient (serum ferritin ≤30μg·L-1), exercising women (n=32). HMB was identified to be common (37% elite athletes, 36% marathon runners), and associated with perceived disruption to exercise training/performance and fatigue, but these relationships were independent of iron status. Iron repletion improved exercise and aerobic capacity, but only in those more severely iron deficient (serum ferritin < 15μg·L-1), with wide individual variation, unrelated to baseline serum ferritin. In conclusion, HMB is a risk factor for ID, physiological and psychological function decrements in exercising women. Intravenous iron repletion effectively restores iron status and improves functional exercise capacity when true ID exists. Serum ferritin as a biomarker for ID and its associated normative data should be re-evaluated to avoid false positive ID diagnosis.