Bibliography: leaves 90-98.

Includes bibliographical references (leaves 76-86).

Introduction: Although there are numerous health benefits associated with participating in regular physical activity, there is also an increased risk of sustaining injuries, in particular musculoskeletal soft tissue injuries. Both an increased and decreased joint range of motion (ROM) has been reported as one of the intrinsic risk factors for these injuries. Similarly to injury, the ROM trait has also been associated with various extrinsic and intrinsic factors. Extrinsic factors that are associated with ROM include level and type of sports participation and temperature. Intrinsic factors include age, gender, limb dominance, weight/BMI, height, prior injury, flexibility training, ethnicity and genotype. It has been reported that ROM is a largely (47-70%) heritable trait in both pathological and apparently healthy populations. Mutations within the COL5A1 gene cause classic Ehlers-Danlos Syndrome (EDS) which present with, among other clinical signs, generalised joint hypermobility. Furthermore, a COL5A1 gene sequence variant, the BstUI Restriction Fragment Length Polymorphism (RFLP), has previously been shown to be associated with ROM measurements in a cohort containing individuals with a history of Achilles tendon injuries. Objectives: The aim of this study was, therefore, to investigate the association between the COL5A1 BstUI (C/T) and DpnII (C/T) RFLPs, as well as non-genetic intrinsic and extrinsic factors, and ROM measurements in an apparently healthy and physically active population. 15 Methods: The sit and reach (SR), passive straight leg raise (SLR) and shoulder internal (ShIR) and external rotation (ShER) assessments were performed on 325 (204 males, 121 females) white, apparently healthy and physically active subjects. Subjects were genotyped for the BstUI (SNP rs12722) and DpnII (SNP rs13946) RFLPs within the 3-untranslated region (UTR) of the COL5A1 gene. Level and type of sport participation, age, gender, limb dominance, height, weight, BMI, waist circumference, prior injury and flexibility training were also recorded to investigate possible associations with ROM. Results: There was a significant interaction between age and COL5A1 BstUI genotype with SR ROM. Subjects with a CC genotype were 'protected' against the commonly reported age-related decline in SR ROM. This divergence in response to aging resulted in a significant difference in the mean SR ROM between the BstUI RFLP genotype groups of the 'old' ('¥35 years) (TT=225 ± 96 mm, TC=245 ± 100 mm, CC=321 ± 108 mm, N=96, p=0.017), but not the 'young' (<35 years) (N=197, p=0.626) subjects. While the DpnII RFLP displayed a similar pattern of divergence in SR ROM with aging, this interaction was not significant. Nevertheless, the SR means were significantly different between DpnII genotypes in the 'old' group when the TT and TC genotypes (T allele) were combined and compared against the CC genotype (T allele=244 ± 98 mm, CC genotype=332 ± 15 mm, N=93, p=0.032). Furthermore, flexibility training (stretching) was associated with increased ROM only in the BstUI TT genotype, suggesting a genotype-specific response. Of all the intrinsic and extrinsic factors 16 investigated in this cohort, only gender and genotype (either BstUI or DpnII RFLPs) were shown to contribute to SR ROM variance through multivariate analysis. Some inconsistent associations with intrinsic and extrinsic factors were observed with the SLR and shoulder ROM assessments, although small sample size and poor reliability of these measures made the results difficult to interpret with confidence. Conclusion: The significant interaction of COL5A1 BstUI RFLP genotype with age explains the differences in SR ROM measurements observed in older, but not younger, apparently healthy and physically active individuals. A similar, non-significant pattern in the DpnII RFLP resulted in significantly different SR ROM for the T allele in comparison to the CC genotype. Besides genotype, gender also an contributed significantly to SR ROM variance in the 'old' cohort. Genetic sequence variants, in conjunction with commonly listed non-genetic intrinsic and extrinsic factors, need to be considered in order to understand the observed variance in ROM in apparently healthy and physically active populations. Keywords: COL5A1 genotype, range of motion (ROM), apparently healthy and physically active population, intrinsic and extrinsic factors, age, flexibility training.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiac disorder characterised by structural and functional abnormalities of the right ventricle with or without left ventricular involvement. In 1994, Task Force criteria (TFC) were proposed for the diagnosis of ARVC and were found to be highly specific but lacked sensitivity. In 2010, revised TFC were proposed to increase sensitivity and facilitate diagnosis in those with subtle phenotypes. Purpose: Many participants of ARVC registries have been enrolled using the 1994 TFC and not re-analysed using the 2010 TFC. We retrospectively compared the utility of both TFC for the diagnosis of mutation-positive probands in the IMHOTEP (The African Cardiomyopathy and Myocarditis Registry Program) study with the aim of identifying diagnostic changes that may have clinical impact. Method: 162 participants with the suspicion of ARVC were referred between May 2003 and May 2018 to our ARVC registry. 150 cases were reviewed using the same ECG and imaging data to fulfil both TFC, and were re-classified by a diagnostic panel at Groote Schuur Hospital, Cape Town. Results: Sixty-eight participants were diagnosed with ARVC by the diagnostic panel and included into the registry; 14/68 participants with ARVC were found to be mutation-positive. Eighty-two participants were found to have an alternative diagnosis or insufficient criteria and were excluded from the ARVC registry. Mutation-positive probands presented at a significantly younger age compared to the mutation-negative group (29 ± 14 years versus 39 ± 13 years, p=0.009), suggesting an earlier onset of ARVC. Common reasons for presentation in the mutation-positive cohort included palpitations (79%) and presyncope (64%), with Page 11 of 78 approximately twice the number of participants presenting with sustained ventricular tachycardia (VT) compared to mutation-negative participants (79% versus 47%, p=0.036). The diagnostic yield of the 2010 versus 1994 TFC (n=68) revealed more participants with a definite diagnosis, and less featuring in possible and no criteria categories. A 67% (n=8) change in diagnosis from 1994 borderline to 2010 definite, and an 88% (n=7) change from 1994 possible to 2010 borderline, were observed. Mutation-positive participants had a higher yield for definite ARVC when compared to mutation-negative participants. We subsequently analysed the contribution of each diagnostic modality at fulfilling TFC in our mutation-positive definite participants and found CMR contribution statistically significant, p=0.021. Conclusion: Our study found that mutation-positive probands were found to be younger, more likely to present with sustained VT, fulfilled a significantly larger number of major 2010 TFC than mutation-negative probands, and that the 2010 TFC for structural and repolarisation abnormalities were more useful in diagnosing ARVC compared to 1994 TFC. We found a significant evolution in classification between both TFC, suggesting that re-classification of participants recruited in traditional ARVC registries according to updated criteria is worthwhile.

Includes bibliographical references.

Includes abstract. Includes bibliographical references.

Includes bibliographical references. / The high occurrence of vascular disease in the 20th century has been the driving force for researchers to produce a successful small diameter synthetic graft. Large diameter synthetic grafts remain patent for extended periods due to high flow rate, while smaller diameter grafts occlude more readily. Mechanical property mismatch between graft and host artery has been cited as one of the major factors that contribute to graft occlusion. It has thus been important to develop a readily available graft that is accepted by the body and does not cause flow abnormalities and stress-concentrations at graft-artery junctions. The object of this project was to ascertain the effect of an adventitial reinforcement on elastic compliance of synthetic porous polyurethane grafts.

The purpose of this study is to examine the influence of silicosis and the occupation of gold mining on respiratory symptoms, lung function and tuberculosis in a working population of black, migrant, South African gold miners. No previous study has examined a working population of these men.

Myasthenia gravis (MG) is an autoimmune disease in which pathogenic antibodies target specific neuromuscular junction proteins, most frequently acetylcholine receptors (AChR). Among those without detectable AChR-antibodies, a subgroup of patients has antibodies directed against muscle-specific tyrosine kinase (MuSK). In MG the pathogenic antibodies result in failure of neuromuscular transmission with consequent fatiguable skeletal muscle weakness. MG frequently affects the extraocular muscles (EOMs) early in the course of the disease, resulting in diplopia and ptosis, which is usually reversible with treatment. A treatment-resistant ophthalmoplegia and ptosis occurs as a complication of MG in a distinct subset of cases referred to as OP-MG. The EOMs are highly specialised muscle tissue with a unique physiological and immunological microenvironment with a large satellite cell niche, a distinct muscle fibroblast population, different transcriptional and cellular signaling pathways and fewer intrinsic complement regulatory proteins to protect them against antibody- activated complement-mediated damage. We hypothesised that in OP-MG, there is a differential response of the EOMs to the underlying MG disease process(es) on a genetic and molecular level, resulting in abnormal myofibre homeostasis. We aimed to report descriptive clinical-pathological data pertaining to EOM function and histopathological and ultrastructural EOM tissue analysis of a patient with OP- MG versus that of a non-MG control (both consented to EOM donation at ocular realignment surgery). EOM tissue from an OP-MG individual with AChR- and MuSK- antibody negative MG, demonstrated predominantly myopathic pathology and ultrastructural evidence of mitochondrial stress. The OP-MG EOM findings differ from the control EOM, which showed normal muscle histopathology in a patient undergoing strabismus surgery for a sensory exotropia in a non-seeing eye (loss of retinal stimulus for fusion) and a similar duration of deviation. These OP-MG findings appear to better correlate with previously reported histology/ultrastructure in limb muscle in MuSK-positive MG rather than AChR-positive MG. We next focussed on transforming growth factor beta-1 (TGFβ1) as a critical cytokine involved in muscle repair. An auto-induction pathway in muscle allows TGFβ1 expression to influence the transdifferentiation of satellite cells into myofibroblasts or myoblasts. In orbital fibroblasts, TGFβ1 has also been shown to upregulate decay accelerating factor (DAF), a complement regulatory protein expressed at lower levels in EOMs than other muscles, which should protect against complement-mediated injury. We established OP-MG and control-MG phenotype-specific dermal fibroblast cell lines and performed immunoblotting to evaluate TGFβ1-induced Smad3 phosphorylation and Daf expression in mouse myotubes. We demonstrated repression of phosphorylated-Smad3, a marker of the canonical TGFβ1 pathway, in OP-MG versus control MG fibroblasts after treatment with TGFβ1. We also demonstrated that TGFβ1 significantly upregulates Daf expression levels in mouse myoblasts. Taken together, these results suggest that OP-MG fibroblasts (and possibly myofibroblasts) are likely to be more susceptible to complement-mediated damage and abnormal myofibrogenesis due to their altered response to TGFβ1 stimulation and secondary DAF upregulation. Finally we investigated the feasability of establishing an in vitro disease model for MG or OP-MG by reprogramming dermal fibroblasts into disease phenotype-specific induced pluripotent stem (iPS) cells. We successfully generated and characterised iPS cells for one individual. However, this process was very labour-intensive, cost-inefficient and time-consuming, taking approximately four months to establish pluripotency in a single patient and thereby limited its further application(s). In conclusion, the EOM ultrastructural findings of an OP-MG case are novel and show similar findings to those described in limb skeletal muscle of MuSK-positive MG patients. The TGFβ1 pathway appears to be differentially regulated in OP-MG compared to control-MG cases and this may impact DAF upregulation in the EOMs in MG patients. Finally, our group is exploring an alternative method of establishing a 'disease-in-a-dish' model that is more cost-effective and practically feasible than the iPS cell route.

Persistent infection by oncogenic human papillomavirus (HPV) is the primary cause of cervical cancer, a leading cause of cancer deaths in women worldwide. There are no treatments for HPV infection, and although prophylactic vaccines are effective and safe, they are HPV type specific, provide little therapeutic benefit and developing countries often have limited access to these. Therefore, additional measures against HPV infection are urgently needed. Preventing HPV entry into host cells is an attractive option for therapeutic intervention. The HPV capsid is icosahedral and consists of two proteins, L1 and L2, which participate in entry and infection of host cells. During entry, the virus capsid attaches to the cell surface via binding to heparan sulphate proteoglycans (HSPGs). Cleavage of L2 by a host protease, furin, is necessary for infection and is thought to facilitate a conformational change in the virus capsid. Furin cleavage may affect the ability of HPV to bind to sulphated glycoproteins and a HSPG substitute, heparin. Understanding these proposed structural changes may aid in the development of therapeutics targeting virus entry. Here, we directly visualize the conformation changes to HPV16 pseudovirions (HPV16 PsVs) resulting from cleavage of L2 by exogenous furin using cryoelectron microscopy (cryo-EM). At 5 Å resolution, we observed that furin-cleaved HPV16 PsVs capsids display widespread changes in the arrangement of capsomeres relative to uncleaved control virions. This structural change is relevant because heparin has previously been observed to bind to the HPV16 capsid in the canyon surrounding the capsomere at the five-fold icosahedral symmetry axis, but not in other canyons between capsomeres, related by pseudo-symmetry. This suggests that differences in the relative orientations of the surrounding capsomeres to each other either prevent or allow heparin binding. We observed a narrowing of the putative heparin binding site by 0.4 Å after furin cleavage and propose that this change may be responsible for the transfer of HPV from cell-surface HSPGs to the unknown entry receptor(s) by a yet unidentified mechanism.