Fong Siu Lai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 187-196). / Acknowledgement --- p.v / Abstract --- p.vii / Chapter Chapter One --- INTRODUCTION --- p.1 / Chapter Chapter Two --- LITERATURE REVIEW --- p.4 / Chapter 1 --- STRUCTURE OF SKIN --- p.4 / Chapter 1.1 --- epidermis / Chapter 1.1.1 --- stratum corneum / Chapter 1.1.2 --- stratum lucidum / Chapter 1.1.3 --- stratum granulosum / Chapter 1.1.4 --- stratum spinosum / Chapter 1.1.5 --- stratum germinativum / Chapter 1.2 --- dermis / Chapter 1.2.1 --- collagen / Chapter 1.2.2 --- elastin / Chapter 1.2.3 --- reticulin / Chapter 1.2.4 --- fibroblasts / Chapter 1.2.5 --- ground subsatnce / Chapter 1.3 --- dermo-epidermal junction / Chapter 1.4 --- skin appendages / Chapter 1.4.1 --- hair / Chapter 1.4.2 --- nails / Chapter 1.4.3 --- glands / Chapter 1.5 --- cutaneous vascular system / Chapter 1.5.1 --- cutaneous blood flow and its significance / Chapter 1.5.2 --- cutaneous lymphatic flow / Chapter 2 --- FUNCTIONS OF SKIN --- p.24 / Chapter 2.1 --- protection / Chapter 2.2 --- sensation / Chapter 2.3 --- thermal regulation / Chapter 2.4 --- absorption / Chapter 2.5 --- protection against ultraviolet radiation / Chapter 2.6 --- storage / Chapter 3 --- BIOMECHANICS OF SKIN --- p.28 / Chapter 3.1 --- skin elasticity and the physical variation / Chapter 3.2 --- mechanical properties / Chapter 3.2.1 --- tensile strength / Chapter 3.2.2 --- distensibility / Chapter 3.2.3 --- Young's modulus / Chapter 3.2.4 --- visco-elastic character / Chapter 3.2.5 --- hysteresis / Chapter 3.3 --- fibre orientation / Chapter 3.4 --- mechanical considerations / Chapter 3.5 --- physiological factors / Chapter 3.6 --- clinical application / Chapter 4 --- PHYSIOLOGICAL RESPONSE OF HUMAN SKIN --- p.47 / Chapter 4.1 --- response to mechanical loading / Chapter 4.1.1 --- triple response / Chapter 4.1.2 --- reactive hyperaemia / Chapter 4.2 --- thermal response / Chapter 4.2.1 --- skin temperature / Chapter 4.2.2 --- response to heat / Chapter 4.2.3 --- response to cold / Chapter 4.3 --- local tissue response to burn / Chapter Chapter Three --- BACKGROUND OF THE PRESENT STUDY --- p.55 / Chapter 1 --- BURN INJURIES --- p.55 / Chapter 1.1 --- nature / Chapter 1.2 --- depth / Chapter 1.3 --- extent / Chapter 1.4 --- location of burn / Chapter 1.5 --- age / Chapter 1.6 --- "associated major trauma, inhalation injury" / Chapter 1.7 --- general health status / Chapter 2 --- WOUND HEALING PROCESS --- p.65 / Chapter 2.1 --- role of collagen in wound healing / Chapter 2.2 --- role of oxygen in wound healing / Chapter 2.3 --- role of fibroblasts and myofibroblasts in wound healing / Chapter 2.4 --- role of mast cells in wound healing / Chapter 3 --- HYPERTROPHIC SCAR --- p.71 / Chapter 3.1 --- aetiological factors / Chapter 3.1.1 --- age / Chapter 3.1.2 --- time for wound healing / Chapter 3.1.3 --- racial factor / Chapter 3.1.4 --- depth of injury / Chapter 3.1.5 --- location / Chapter 3.1.6 --- tension / Chapter 3.2 --- characteristics / Chapter 3.3 --- pathogenesis of hypertrophic scar / Chapter 3.3.1 --- blood flow / Chapter 3.3.2 --- tissue gas / Chapter 3.3.3 --- filamentous material / Chapter 3.3.4 --- mast cells / Chapter 3.3.5 --- chondroitin sulfate / Chapter 3.3.6 --- enzyme proline hydroxylase / Chapter 3.4 --- histopathology / Chapter 3.5 --- response towards pressure / Chapter 4 --- TREATMENT OF POST-BURN HYPERTROPHIC SCAR AND THEIR RESPONSE --- p.92 / Chapter 4.1 --- surgery / Chapter 4.2 --- radiotherapy / Chapter 4.3 --- ultrasonics / Chapter 4.4 --- chemotherapy/ intralesional injection of steroid / Chapter 4.5 --- pressure therapy / Chapter 4.6 --- topical silicone gel / Chapter 4.6.1 --- mechanics / Chapter 4.6.2 --- bacteriology / Chapter 4.6.3 --- water-vapour transmission rate / Chapter 4.6.4 --- appearance in the Scanning Electronic Microscope / Chapter 4.7 --- prevention of hypertrophic scar and scar contracture / Chapter 5 --- ASSESSMENT TOOLS FOR HYPERTROPHIC SCAR AND THE CLINICAL APPLICATION --- p.105 / Chapter 5.1 --- clinical observation of the appearance / Chapter 5.2 --- ultrasonography and thickness / Chapter 5.2.1 --- ultrasound / Chapter 5.2.2 --- pulse-echo distance measurement / Chapter 5.2.3 --- echo generation / Chapter 5.2.4 --- transducer beam pattern / Chapter 5.2.5 --- ultrasound instrumentation / Chapter 5.2.6 --- application of ultrasound in the study of hypertrophic scar thickness / Chapter 5.3 --- elastometry (Cutometer) and elasticity / Chapter 5.4 --- application of elastometry / Chapter Chapter Four --- OBJECTIVES & METHODOLOGY OF THE STUDY --- p.123 / Chapter 1 --- Objectives of the study --- p.123 / Chapter 2 --- Study subjects --- p.123 / Chapter 3 --- Methodology --- p.125 / Chapter 4 --- Assessment of thickness of hypertrophic scar --- p.128 / Chapter 5 --- Assessment of visco-elasticity of hypertrophic scar --- p.130 / Chapter 6 --- Clinical rating scale --- p.133 / Chapter 7 --- Study of normal skin as control --- p.133 / Chapter 8 --- Reliability of the ultrasound and cutometer measurement --- p.134 / Chapter Chapter Five --- RESULTS --- p.136 / Chapter 1 --- Inter- and intra- examiner variations of the ultrasound and cutometer measurement --- p.136 / Chapter 2 --- Comparison with normal skin control --- p.138 / Chapter 3 --- Results of ultrasonographic measurements of thickness of hypertrophic scar and its correlation with the clinical grading --- p.139 / Chapter 4 --- Results of Cutometer reading (visco-elastic properties) and the correlation with clinical grading --- p.142 / Chapter 5 --- Observation from raw data --- p.152 / Chapter Chapter Six --- DISCUSSION --- p.154 / Chapter 1 --- Measuring thickness with ultrasonography and clinical grading --- p.157 / Chapter 2 --- Elastic properties of hypertrophic scar and clinical grading --- p.158 / Chapter 3 --- The predictive value of the ultrasonography and elastometry through monthly longitudinal measurement --- p.161 / Chapter 4 --- Inter- and intra- examinar reliability of the ultrasonography and elastometry in the assessmetn of post-burn hypertrophic scar --- p.164 / Chapter 5 --- "The use of a composite ""Visco-elasticity-Thickness Chart"" and case studies" --- p.165 / Chapter 6 --- Limitations of the study --- p.182 / Chapter Chapter Seven --- CONCLUSION AND RECOMMENDATION FOR FURTHER STUDY --- p.184 / REFERENCES --- p.187 / APPENDICES --- p.197 / Appendix 1 Patients' record --- p.197 / Appendix 2 Record of the scars --- p.200 / Appendix 3 Clinical Grading of the hypertrophic scar --- p.202 / Appendix 4 Measurement of the visco-elastic properties --- p.204 / Appendix 5 Ultrasonic measurements of the hypertrophic scars --- p.235 / Appendix 6 List of graphs --- p.237 / Appendix 7 List of figures --- p.238 / Appendix 8 List of tables --- p.240

Background: Photoageing is due to the cumulative effects of sun exposure superimposed on chronological cutaneous ageing. Clinically, amongst Fitzpatrick skin types I-IV, it is thought that two main phenotypes of facial photoageing may exist: atrophic smooth telangiectactic skin (AP) and hypertrophic coarse wrinkled skin (HP). AP is more prone to the development of non-melanoma skin cancers (NMSC). Aim: To investigate the morphological and histological differences in photoexposed facial skin and photoprotected buttock skin from prototypic subjects with atrophic skin and hypertrophic phenotypes. Patients and Methods: Subjects with atrophic and hypertrophic skin were pre-selected based on their phenotype from the general population (n=40; n=20, hypertrophic phenotype, 10 males, 10 females; n=20, atrophic phenotype, 10 males, 10 females). All subjects had a 4mm punch biopsy taken from their UV exposed facial skin (cheek) and a 6mm punch biopsy taken from their UV-protected buttock skin. All selected participants were: ex- or non-smokers, had no history of inflammatory skin disease, and aged > 50 years (mean ± SE); [AP (78.7y ±2.02) and HP (74.6y ±2.08)]. Staining for elastic fibres, fibrillin-rich microfibrils (FRMs), collagen VII and Von Willebrand Factor (vWF) as well as morphometric measurements including dermal-epidermal convolution and epidermal thickness were performed. Demographic data and VISIA® photoassessments were additionally compiled. Analysis using ImageJ software and SPSS (Statistics 20; IBM) was performed. Results: We found that AP epidermis was thicker than HP (p < 0.0001) but there were no significant differences in dermal-epidermal junction (DEJ) convolution between phenotypes (p > 0.05). The percentage of dermis occupied by mature elastin fibres was significantly greater in HP than AP (p < 0.0001), but the dermis of HP was less enriched in fibrillin-rich microfibrils than AP (p < 0.05). AP was found to be collagen VII-poor compared to HP (p < 0.05) but, as expected, was more vascular with a greater number of blood vessels (p < 0.001 & p < 0.0001, respectively). No differences were found in any of these biomarkers in sun-protected buttock skin obtained from the same patients. Conclusion: This is a novel, exploratory study which demonstrates that the stroma in AP facial skin is characterised by less solar elastosis and collagen VII expression and more fibrillin-rich microfibrils, increased vascularisation compared to the HP phenotype. HP and AP appear to be distinct clinical and histological entities.

No description available.

No description available.

Myosin subfragment-2 (S2) is an intrinsically unstable coiled coil. This dissertation tests if the mechanical stability of myosin S2 would influence the availability of myosin S1 heads to actin thin filaments. The elevated instability in myosin S2 coiled coil could be one of the causes for hypercontractility in Familial Hypertrophic Cardiomyopathy (FHC). As hypothesized FHC mutations, namely E924K and E930del, in myosin S2 displayed an unstable myosin S2 coiled coil compared to wild type as measured by Fluorescence Resonant Energy Transfer (FRET) and gravitational force spectroscopy (GFS). To remedy this, anti-S2 peptides; the stabilizer and the destabilizer peptides by namesake were designed in our lab to increase and decrease the stability of myosin S2 coiled coil to influence the actomyosin interaction. Firstly, the effectiveness of anti-S2 peptides were tested on muscle myosin S2 peptides across MYH11 (smooth), MYH7 (cardiac), and MYH2 (skeletal) with GFS and FRET. The results demonstrated that the mechanical stability was increased by the stabilizer and decreased by the destabilizer across the cardiac and skeletal myosin S2 isoform but not for the smooth muscle isoform. The destabilizer peptide had dissociation binding constants of 9.97 × 10-1 μM to MYH7 isoform, 1.00 μM to MYH2 isoform, and no impact on MYH11, and the stabilizer peptide had dissociation binding constants of 2.12 × 10-2 μM to MYH7 isoform, 3.41 × 10-1 μM to MYH2 isoform, and no impact on MYH11 revealed by FRET. In presence of the stabilizer, FRET assay, affinity of the E930del and E924K increased by 10.23 and 0.60 fold respectively. The force required to uncoil muscle myosin S2 peptides in the presence of the stabilizer peptide was more than in its absence in muscle myosin S2 isoforms of MYH7 (1.80 fold higher), MYH2 (1.40 fold higher), and E930del (2.60 fold higher) and no change for MYH11 compared to control. The force required to uncoil muscle myosin S2 in presence of the destabilizer was less than in its absence in both MYH7 (2.00 fold lower) and MYH2 (2.5 fold lower) but the same for MYH11 compared to their controls. Both FRET and GFS assays demonstrated that both anti-S2 peptides do not have any impact on smooth muscle myosin S2 isoform. In FRET assay, there was no significant difference in the lifetime value in the presence or absence of anti-S2 peptides in smooth muscle myosin S2. In GFS assay, there was no significant difference in the force required to uncoil the dimer in presence or absence of the anti-S2 peptides smooth muscle myosin S2. Effectively, the stabilizer peptide improved the stability of FHC mutant (E924K and E930del) myosin S2 peptide. FHC mutations showed high lifetime value in FRET assay and low force to uncoil coiled coil myosin S2 in GFS assay. In the presence of the stabilizer, lifetime value decreased in FRET assay and more force was required to uncoil myosin S2 coiled coil in GFS assay. This study demonstrated that structure of muscle myosin S2 can be altered by small peptides. The stabilizer peptide enhanced dimer formation in wild type and mutant cardiac, and skeletal myosin S2 peptides, and destabilizer increased flexibility of cardiac and skeletal myosin S2 wild type peptide. Neither anti-S2 peptides had impacts on smooth muscle myosin S2 isoform. The study thus effectively demonstrates the mechanical stability of myosin S2 coiled coil in striated muscle system could be modified using the specific anti-S2 peptides. Stabilizer of the anti-S2 peptide was effective to remedy the dampened stability of FHC myosin S2 coiled coil thus providing a new dimension of treating cardiovascular and skeletal muscle disorders by targeting the structural property of muscle proteins.

The stability of myosin subfragment 2 was analyzed using gravitational force spectroscopy. The region was found to destabilize under physiological force loads, indicating the possibility that subfragment 2 may uncoil to facilitate actin binding during muscle contraction. As a control, synthetic cofilaments were produced to discover if the observations in the single molecule assay were due to the lack of the stability provided by the thick filament. Statistically, there was no difference between the single molecule assay data and the synthetic cofilament assay data. Thus, the instability of the region is due to intrinsic properties within subfragment 2.

No description available.

Background: Clopidogrel is commonly prescribed to cats with perceived increased risk of thromboembolic events, but little information exists regarding its antiplatelet effects. ObjectiveTo determine effects of clopidogrel on platelet responsiveness in cats with or without the A31P mutation in the MYBPC3 gene. A secondary aim was to characterize variability in feline platelet responses to clopidogrel. AnimalsFourteen healthy cats from a Maine Coon/outbred mixed Domestic cat colony: 8 cats homozygous for A31P mutation in the MYPBC3 gene and 6 wild-type cats without the A31P mutation. MethodsEx vivo study. All cats received clopidogrel (18.75 mg PO q24h) for 14 days. Before and after clopidogrel treatment, adenosine diphosphate (ADP)-induced P-selectin expression was evaluated. ADP- and thrombin-induced platelet aggregation was measured by optical aggregometry (OA). Platelet pVASP and ADP receptor response index (ARRI) were measured by Western blot analysis. ResultsPlatelet activation from cats with the A31P mutation was significantly (P = .0095) increased [35.55% (18.58-48.55) to 58.90% (24.85-69.90)], in response to ADP. Clopidogrel treatment attenuated ADP-induced P-selectin expression and platelet aggregation. ADP- and PGE(1)-treated platelets had a similar level of pVASP as PGE(1)-treated platelets after clopidogrel treatment. Clopidogrel administration resulted in significantly lower ARRI [24.13% (12.46-35.50) to 11.30% (-7.383 to 23.27)] (P = .017). Two of 13 cats were nonresponders based on OA and flow cytometry. Conclusion and Clinical ImportanceClopidogrel is effective at attenuating platelet activation and aggregation in some cats. Cats with A31P mutation had increased platelet activation relative to the variable response seen in wild-type cats.

by Cheng Chi Wa. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 110-120). / Abstract also in Chinese. / Title --- p.i / Abstract --- p.ii / Acknowledgement --- p.iv / Abbreviations --- p.v / Abbreviation Table for Amino Acids --- p.vi / Table of Contents --- p.vii / List of Figures --- p.xii / List of Tables --- p.xv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Literature review --- p.2 / Chapter Part I --- Hypertrophic Scar / Chapter 2.1 --- Definition of hypertrophic scar --- p.2 / Chapter 2.2 --- Pathology --- p.2 / Chapter 2.3 --- Epidemiology findings --- p.3 / Chapter 2.3.1 --- Ethnicity --- p.3 / Chapter 2.3.2 --- Age --- p.3 / Chapter 2.3.3 --- Body location --- p.3 / Chapter 2.4 --- Mechanism of cutaneous wound healing --- p.4 / Chapter 2.4.1 --- Phase I - Haemostasis and inflammation --- p.4 / Chapter 2.4.1.1 --- Haemostasis --- p.6 / Chapter 2.4.1.2 --- Early phase of inflammation --- p.6 / Chapter 2.4.1.3 --- Late phase of inflammation --- p.7 / Chapter 2.4.2 --- Phase II - Re-epithelialization --- p.7 / Chapter 2.4.2.1 --- Migration of epidermal keratinocytes --- p.8 / Chapter 2.4.2.2 --- Migration of fibroblasts --- p.8 / Chapter 2.4.2.3 --- Angiogenesis --- p.9 / Chapter 2.4.3 --- Phase III - Tissue remodeling --- p.10 / Chapter 2.4.3.1 --- Cell maturation and apoptosis --- p.10 / Chapter 2.4.3.2 --- Exrtracellular matrix remodeling --- p.10 / Chapter 2.5 --- Alteration of wound healing - Possible pathogenic factors of hypertrophic scar --- p.11 / Chapter 2.5.1 --- Changes in Phase I-Inflammation --- p.13 / Chapter 2.5.2 --- Changes in Phase II - Re-epithelialization/ tissue formation --- p.14 / Chapter 2.5.3 --- Changes in Phase III - Tissue remodeling --- p.15 / Chapter 2.6 --- The Role of fibroblasts in the formation of hypertrophic scar --- p.16 / Chapter 2.6.1 --- Functions of fibroblasts in wound healing --- p.16 / Chapter 2.6.2 --- Suggested aetiological role in the formation of hypertrophic scar fibroblasts --- p.16 / Chapter 2.6.2.1 --- Fibroproliferation disorder --- p.18 / Chapter 2.6.2.2 --- Extracellular Matrix remodeling disorder --- p.18 / Chapter a) --- CoUaqen --- p.18 / Chapter b) --- Proteoglycan --- p.19 / Chapter 2.6.2.3 --- Other differentially expressed factors --- p.20 / Chapter 2.7 --- Treatment of hypertrophic scar --- p.21 / Chapter Part II --- Differential Display / Chapter 2.8 --- Current approaches for the studies of differential gene expression --- p.23 / Chapter 2.9 --- Comparison amongst different approaches --- p.23 / Chapter 2.10 --- The strategy of Differential Display RT-PCR (DDRT-PCR) --- p.24 / Chapter 2.11 --- The application of DDRT-PCR to identify differentially expressed genes --- p.26 / Chapter Chapter 3 --- Aims and Strategies --- p.27 / Chapter Chapter 4 --- Methods and Materials --- p.29 / Chapter 4.1 --- Materials --- p.29 / Chapter 4.2 --- Clinical specimen collection --- p.31 / Chapter 4.3 --- Primary explant culture --- p.31 / Chapter 4.4 --- Immunohistochemical staining --- p.32 / Chapter 4.5 --- Total RNA extraction --- p.32 / Chapter 4.6 --- DNase I digestion --- p.33 / Chapter 4.7 --- Differential display-RTPCR (DD-RTPCR) --- p.33 / Chapter 4.8 --- Polyacrylamide gel electrophoresis --- p.34 / Chapter 4.9 --- Reamplification of the differentially expressed fragments --- p.35 / Chapter 4.10 --- Molecular cloning of the DNA fragments --- p.35 / Chapter 4.11 --- Screening and miniprep of the plasmid DNA --- p.36 / Chapter 4.12 --- Cycle sequencing --- p.38 / Chapter 4.13 --- Data analysis --- p.38 / Chapter 4.14 --- RT-PCR --- p.39 / Chapter 4.15 --- Probe labeling by PCR with DIG-dUTP --- p.40 / Chapter 4.16 --- Southern blotting --- p.41 / Chapter Chapter5 --- p.42 / Chapter 5.1 --- Clinical Specimen --- p.42 / Chapter 5.2 --- Primary explant culture --- p.42 / Chapter 5.3 --- The total RNA extraction from the cultured fibroblast --- p.45 / Chapter 5.4 --- Differential display RT-PCR --- p.47 / Chapter 5.5 --- Reamplification of the DNA fragments --- p.49 / Chapter 5.6 --- Molecular cloning of the DNA fragment --- p.53 / Chapter 5.7 --- DNA sequencing of the inserts --- p.58 / Chapter 5.8 --- Analysis and identification of the DNA sequences --- p.62 / Chapter 5.9 --- Semi-quantitative RT-PCR analysis of the differentially expressed genes --- p.76 / Chapter Chapter6 --- p.87 / Chapter Part I --- Validity of the Findings / Chapter 6.1 --- The Limitation of Tissue Sampling --- p.87 / Chapter 6.2 --- Tissue Culture model --- p.88 / Chapter 6.3 --- Differential Display RT-PCR --- p.89 / Chapter 6.3.1 --- Identification of the differentially expressed genes --- p.89 / Chapter 6.3.2 --- Confirmation of the differentially expressed genes --- p.91 / Chapter 6.4 --- Technical difficulties and Limitations --- p.92 / Chapter 6.4.1 --- Sampling --- p.92 / Chapter 6.4.2 --- Primary tissue culture --- p.93 / Chapter Part II --- Significance and Future Studies / Chapter 6.5 --- Down-regulation of thrombospondin 1 (TSP 1) in the hypertrophic scar fibroblasts --- p.94 / Chapter 6.6 --- Biochemical and biological functions of TSP1 --- p.96 / Chapter 6.6.1 --- The biochemical functions of TSP1 --- p.96 / Chapter 6.6.2 --- The biochemical functions of TSP1 --- p.97 / Chapter 6.7 --- The role of TSP 1 in the pathogenesis of hypertrophic scar --- p.98 / Chapter 6.7.1 --- Down-regulation of TSP 1 may be responsible for the excessive microvessels in hypertrophic scar --- p.98 / Chapter 6.7.2 --- Down-regulation of TSP 1 may be responsible for the failure of the apoptosis of the fibroblasts in the hypertrophic scar --- p.101 / Chapter 6.8 --- Expression of TSP 1 during wound healing --- p.103 / Chapter 6.9 --- Expression of TSP 1 in hypertrophic scarring --- p.107 / Chapter 6.10 --- Cytochrome b561 and its biological function --- p.109 / Chapter 6.11 --- Future studies --- p.108 / Chapter 6.11.1 --- The expression of TSP 1 in hypertrophic scarring and normal wound healing --- p.108 / Chapter 6.11.2 --- The expression of cytochrome b561 --- p.109 / Chapter 6.11.3 --- A full scale study of differential display RT-PCR --- p.109 / References --- p.110 / Appendices --- p.121 / Chapter I --- The complete mRNA sequence of thrombospondin1 precursor --- p.121 / Chapter II --- The mRNA sequence of cytochrome b561 --- p.123

Thesis (MScMedSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Left ventricular hypertrophy (LVH) occurs when the cardiomyocytes in the left ventricle become enlarged by increasing in mass in response to haemodynamic pressure overload. This can either be attributed to a normal physiological response to exercise or can be the result of a maladaptive process or disease state, such as chronic hypertension. Hypertrophic cardiomyopathy (HCM) is the most common form of Mendelian-inherited cardiac disease. A defining characteristic thereof is primary LVH that occurs when there are no other hypertrophy-predisposing conditions present. Therefore, HCM provides a unique opportunity to study the molecular determinants of LVH in the context of a Mendelian disorder, instead of in more complex disorders such as hypertension. Over 1000 HCM-causing mutations in 19 genes have been identified thus far, most of them encoding sarcomeric proteins residing in the sarcomeric C-zone. However, for many HCM patients no disease-causing genes have been identified. Moreover, studies have shown phenotypic variation in presentation of disease in, as well as between, families in which the same HCM-causing mutation segregates. This has led many investigators to conclude that genetic modifiers of hypertrophy exist. The aim of the study was to identify novel plausible HCM-causing or modifier genes by searching for interactors of a known HCM-causing protein, namely titin. The hypothesis was that genes encoding proteins, which interact with proteins that are encoded by known HCM-causative genes, may also be considered HCM-causing or may modify the HCM phenotype. To this end, the aim was to identify novel interactors of the 11-domain super-repeat region of titin, which resides within the sarcomeric C-zone, using yeast two-hybrid analysis. Five putative interactors of the 11-domain super-repeat region of titin were identified in this study. These interactions were subsequently verified by colocalisation in H9C2 rat cardiomyocytes, providing further evidence for possible interactions between titin and these proteins. The putative interactor proteins of titin determined from the Y2H library screen were: filamin C (FLNC), phosphatidylethanolamine-binding protein 4 (PEBP4), heart-type fatty acid binding protein 3 (H-FABP3), myomesin 2 (MYOM2) and myomesin 1 (MYOM1). The FLNC gene could be a candidate for cardiac diseases, especially cardiomyopathies that are associated with hypertrophy or developmental defects. The putative interaction of titin and PEBP4 is speculated to be indicative of the formation of the interstitial fibrosis and myocyte disarray seen in HCM. Heart-type fatty acid-binding protein 3 has prognostic value to predict recurrent cardiac events. Its suggested interaction with titin is speculated to play a role in inhibiting its functional abilities. Myomesin 2 is jointly responsible, with MYOM1, for the formation of a head structure on one end of the titin string that connects the Z and M bands of the sarcomere. This is speculated to be linked to a developmental error with the result being a defect in sarcomeric structure formation, which could result in pathologies such as HCM. Therefore, these identified proteins could likely play a functional role in HCM due to their interactions with titin. This research could thus help with new insights into the further understanding of HCM patho-aetiology. / AFRIKAANSE OPSOMMING: Linker ventrikulêre hipertrofie (LVH) ontstaan wanneer die kardiomyosiete in die linkerventrikel vergroot as gevolg van 'n verhoging in massa in reaksie op hemodinamiese drukoorlading. Dit kan toegeskryf word aan 'n normale fisiologiese respons op oefening of kan die gevolg wees van 'n wanaangepaste of siektetoestand, soos chroniese hipertensie. Hipertrofiese kardiomiopatie (HKM) is die mees algemene vorm van Mendeliese oorerflike hartsiekte. 'n Bepalende eienskap daarvan is primêre LVH, wat plaasvind wanneer daar geen ander hipertrofie-predisponerende voorwaardes teenwoordig is nie. Gevolglik bied HKM 'n unieke geleentheid om die molekulêre derterminante van LVH te bestudeer, in die konteks van 'n Mendeliese oorerflike siekte, in plaas van om dit in die meer komplekse siektes soos hoë bloeddruk te bestudeer. Meer as 1000 HKM-veroorsakende mutasies is tot dusver in 19 gene geïdentifiseer. Die meeste van hulle kodeer vir sarkomeriese proteïene wat in die C-sone voorkom. Egter, vir baie HKM-pasiënte is geen siekte-veroorsakende gene al geïdentifiseer nie. Daarbenewens het studies getoon dat variasie in fenotipiese aanbieding van die siekte in, sowel as tussen, families voorkom wat dieselfde HKM-veroorsakende mutasie het. Dit het daartoe gelei dat baie navorsers tot die gevolgtrekking gekom het dat genetiese wysigers van hipertrofie wel bestaan. Die doel van die studie was om nuwe moontlike HKM-veroorsakende of wysiger-gene te identifiseer deur te soek vir interaktors van 'n bekende HKM-veroorsakende proteïen, naamlik titin. Die hipotese was dat gene wat vir proteïene kodeer, wat in wisselwerking is met proteïene wat geïnkripteer word deur bekende HKM-veroorsakende gene, ook oorweeg kan word om HKM te veroorsaak. Dit kan ook die HKM fenotipe verander. Dus was die doel om nuwe interaktors van die 11-domein super-herhaalstreek van titin, soos gevind binne die sarkomeriese C-sone, te identifiseer deur middel van gis-twee-hibried-analise. Vyf vermeende interaktors van die 11-domein super-herhaalstreek van titin is in hierdie studie geïdentifiseer. Hierdie interaksies is later geverifieer met behulp van ko-lokalisering in H9C2-rotkardiomyosiete, wat verdere bewyse vir moontlike interaksies tussen titin en hierdie proteïene verskaf. Die vermeende interaktor-proteïene van titin wat bepaal is vanaf die gis-twee-hibried-biblioteeksifting was as volg: filamin C (FLNC), phosphatidylethanolamine-bindingsproteïen 4 (PEBP4), hart-tipe-vetsuur bindingsproteïen 3 (H-FABP3), myomesin 2 (MYOM2) en myomesin 1 (MYOM1). Die FLNC-geen kan 'n kandidaat vir kardiale siektes, veral kardiomiopatieë, wees wat geassosieer word met hipertrofie of ontwikkelingsafwykings. Die vermeende interaksie van titin en PEBP4 dui daarop om 'n aanduiding te wees vir die vorming van die interstisiële fibrose en miokardiale wanorde, soos gesien in HKM. Hart-tipe-vetsuur bindingsproteïen 3 het prognostiese waarde om herhalende kardiale gebeure te voorspel. Verder dui sy voorgestelde interaksie met titin moontlik daarop dat dit 'n rol kan speel in die inhibering van sy funksionele vermoëns. Myomesin 2 tesame met MYOM1 is verantwoordelik vir die vorming van 'n kopstruktuur aan die een kant van die titinstring wat dan die Z- en M-bande van die sarkomeer verbind. Daar word vermoed dat dit gekoppel is aan 'n ontwikkelingsfout, met die gevolg dat daar 'n defek is in sarkomeriese struktuurvorming, wat weer kan lei tot patologieë soos HKM. / Mrs Wendy Ackerman / Prof Paul van Helden / National Research Foundation (NRF) / Stellenbosch University