Ischaemic heart disease is a major contributor to premature death and heart failure in the Westernised world. Ischaemic injury within the heart may be beneficially modulated by the nucleoside adenosine. Derived from catabolism of ATP, adenosine was initially known as a potent bradycardic and hypotensive agent. However, more recently the protective function of adenosine has been investigated. The protective effects of adenosine are mediated via activation of adenosine receptors: A1, A2A, A2B, and A3 receptors. Activation of these potentially protective (or retaliatory) adenosine receptors hinges upon accumulation of adenosine during ischaemia-reperfusion. This Thesis examines the role and mechanisms of adenosine mediated cardioprotection in young and aged hearts, exploring endogenous and exogenous adenosine receptor activation, genetic manipulation of A1 receptors and adenosine deaminase and pharmacological manipulation of adenosine metabolism. The effects of age on ischaemic responses and adenosine handling and protection are also assessed. The core approach to assess each of the above issues involved the Langendorff isolated mouse heart preparation. Experiments within Chapter 3 focuses on the contractile effects of adenosine receptors in normoxic hearts. This study indicates A2A receptors have no direct effect on contractility, while adenosine exerts positive inotropy independently of coronary flow and perfusion pressure (i.e. Independent of the Gregg phenomenon). In addition, investigations in genetically modified hearts hint at positive inotropy in response to A1 receptors. Since the latter is only evidenced in modified lines, it is possible A1-mediated inotropy may be abnormal or supraphysiological. In Chapter 4 the impact of genetic 'deletion' of A1ARs and/or adenosine deaminase (ADA) on intrinsic tolerance to ischaemia were studied. Data demonstrate that genetic deletion of A1 receptors significantly limits the ability of the mouse myocardium to withstand injury during ischaemic insult. Thus, providing strong support for a role of A1ARs in determining intrinsic tolerance to ischaemia-reperfusion. ADA KO mice confirm protection afforded by endogenous adenosine and the notion of adenosine metabolism modification as a protective strategy. Interestingly, effects of A1AR KO differ from A1AR overexpression or A1AR agonism in that the latter decrease contractile diastolic dysfunction while A1AR KO selectively increase systolic dysfunction and increase oncosis without altering diastolic injury. This challenges current dogma regarding the action of A1 adenosine receptors on ischaemic injury. In Chapter 5 the effects of adenosine metabolism inhibition (via adenosine deaminase (ADA) and adenosine kinase (AK) inhibitors) were studied. Inhibition of adenosine deaminase with the drug EHNA, and adenosine phosphorylation with iodotubercidin significantly protected mouse hearts from ischaemia-reperfusion, reducing contractile dysfunction and cardiac enzyme efflux. However, inhibitors failed to improve the outcome of the aged myocardium. 8-SPT and 5-HD reduced the protective effects of EHNA and iodotubercidin demonstrating thus; cardioprotection via ADA and AK appears to rely on adenosine receptor activation and involves a mitoK ATP dependent mechanism. Since aging is of considerable importance with regard to outcomes of ischaemic heart disease, experiments in Chapter 6 focused on effects of aging (and gender) on cardiovascular function and injury during ischaemia-reperfusion. In assessing post ischaemic outcomes in hearts from young adult (2-4 months), mature adult (8 months), middle aged (12 months), aged (18 months) and senescent (24-28 months) C57/BL/6J mice, data reveal a substantial age-related decline in ischaemic tolerance (which appears selective for myocardial vs. vascular injury). The decline in ischaemic tolerance is expressed primarily within the initial 12 months in both males and females with relatively little further decline with continued aging. There is evidence of a modest improvement in tolerance in senescence vs. aged hearts possibly reflecting selection of a protected phenotype in senescent populations. In addition, mature and middle-aged female hearts showed improved tolerance to ischaemia-reperfusion compared to males, supporting a role for hormonal changes. Effects of aging and purine metabolism were studied in Chapter 7. Data suggest impaired tolerance to ischaemia-reperfusion in older hearts may stem in part from shifts in myocardial purine catabolism. Data reveal reduced accumulation of salvageable and cardioprotective adenosine and enhanced accumulation of poorly salvaged (and potentially injurious) hypoxanthine and xanthine. These changes may potentially predispose the aged myocardium to ischaemic injury and radical generation via the xanthine oxidase reaction. The final data Chapter of this Thesis describes preliminary data regarding aging, signalling and adenosine mediated protection. It was found that protein kinase C (PKC) and A1 receptors mediate protection in young hearts and also that A1 receptors appear to mediate protection via a PKC LindependentLi signalling cascade. In addition, experiments in aged hearts (attempting to elucidate mechanisms behind impaired adenosinergic protection with age) suggest a PKC-independent A1-mediated protection path may be preserved with aging, since A1 receptors continue to offer some protection while PKC activation does not. It is possible the failure of exogenous adenosine to offer protection in aged hearts may result from a lesion at or downstream of PKC.

Stroke is a preventable disease. Minor stroke and transient ischaemic attack (TIA) are important warning signs of the possibility of a major stroke. Worldwide, stroke is the third most common killer and the largest cause of disability. The incidence of stroke is predicted to increase with the predominance of unhealthy lifestyles and the aging population. The adoption of a healthy lifestyle can reduce many of the risk factors. This descriptive study was designed to explore patients’ understanding of modifiable risk factors of cerebrovascular disease. It investigated lifestyle changes actually made, as well as the factors affecting patients’ decisions about whether to make lifestyle changes. The two major factors considered were patients’ sources and level of knowledge and their attitudes and beliefs around making changes. A convenience sample of patients who had suffered a minor stroke or TIA was recruited through a major metropolitan hospital. Thirty-five subjects responded to a postal questionnaire. The mean age was 68 years and 37% of the subjects had sustained some disability as a result of the TIA or minor stroke. The results demonstrated that many subjects had a poor understanding of risk factors of stroke. While smoking was well recognised as a risk factor, subjects showed less awareness of other risk factors, such as excessive alcohol consumption and obesity. Subjects also reported significant confusion regarding diet. Sixty-six percent of subjects depended on doctors as their main source of health information. This may be problematic as the current shortages of General Practitioners has put pressure on doctors to keep appointment times short and reduce the time available for health education. The main barriers to lifestyle change, were lack of motivation, and inadequate, knowledge, guidance, and support and the inability to access good information. Although 83% of subjects suffered from hypertension, medication was the accepted method of control, few subjects realised the significance of lifestyle factors. Nine percent of subjects were only diagnosed with hypertension after their stroke or TIA and few monitor their own blood pressure, despite the wide availability of home monitoring devices. From the findings of this study it is concluded that health promotion and education are very important strategies in the prevention of stroke and it is recommended that this kind of education begins in childhood with tailored, age-specific programs delivered to the public over the lifespan. The role of health screening cannot be underestimated in the detection of risk factors such as hypertension and obesity. Early detection makes effective treatment possible and helps prevent the occurrence of strokes, thus reducing the cost to the community. Long-term health strategies such as improving health resource distribution and enhancing health education are needed where patients and their families participate together in comprehensive education programs. It is hoped that this may lead to a shared understanding, which may translate to patients being more supported, and therefore more able, to make the necessary lifestyle changes. Dysphagia is a common complication following stroke, which can result in significant morbidity and mortality. Multidisciplinary collaboration facilitates management strategies, decision-making and the efficiency of rehabilitation. Nurses are responsible for coordination of management and in particular for continuous monitoring, assessment of swallowing and nutritional state, maintaining safety and preventing complications. An understanding of the issues and strategies relating to management may provide valuable information to enhance the safety, cost-effectiveness and quality of care. A retrospective review of patients’ medical records was used to collect data. A sample of ninety-five adults who were admitted to an Australian public hospital between January 2003 and April 2006, with a diagnosis of dysphagic stroke were recruited. Statistical Package for Social Sciences (SPSS) was used to analyse the quantitative data, while content analysis was used to analyse the qualitative data. All subjects were assessed by a speech pathologist, the mean age was 75 years and 50.5% were male. Except for critically ill subjects, almost all were assessed within three days. Ninety-six percent of subjects had communication problems and 81% had upper limb motor impairment. During hospitalisation almost 60% of subjects had an improvement in their oral intake including 8% resuming their premorbid diet. Eighteen percent were on enteral tube feeding upon discharge, 4% deteriorated and 16% died. It appears that oral intake of most subjects was unsatisfactory. When recorded the mean body weight lost was 2.3kg. At least 22% had malnutrition or dehydration. Forty-five percent aspirated and 22% had respiratory infection. Almost half of the subjects (48%) were discharged to aged care facilities. Eighty percent had no documented follow-up scheduled for management of their dysphagia. Early identification of dysphagia, prudent supervising of appropriate oral intake and mouth care may help to maintain safe swallowing, preventing aspiration and chest infection. Regular checks of body weight, serum albumin level, oral intake and early enteral feeding are essential to guide nutritional support, minimise malnutrition and problematic medication administration. Encouraging oral intake and providing families with support could promote recovery of swallowing skills and help patients to regain the ability to eat independently. Providing helpful information on the care options available may allay patient and family anxiety. A qualified nurse practitioner could assess patients and ensure that a tailored care plan was designed to meet patients’ needs and this may improve the outcomes considerably. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320650 / Thesis (D.Nurs.) - University of Adelaide, School of Population Health and Clinical Practice, 2008

[Truncated abstract] In this thesis the role of lactate measurement has been evaluated in intrapartum assessment of fetal wellbeing. Specifically, I have addressed the question of whether fetal lactate measurement is better than the assessment of fetal heart rate patterns or the measurement of pH at predicting fetal brain injury after intrapartum asphyxia. Using an ovine model of repeated umbilical cord occlusion designed to mimic events which may occur during human labour, I have shown that the measurement of fetal lactate levels after repeated cord occlusion is significantly associated with the severity of brain injury after the asphyxial insult. No significant associations were identified with fetal pH measurements or with the duration of decelerative or compound fetal heart rate patterns; however, this is the first study to describe an association between the duration of both increased fetal heart rate variability and fetal heart rate overshoot with the severity of subsequent brain injury. Although no significant association was identified between fetal arterial pressure measured between umbilical cord occlusions and the grade of brain injury, the studies performed in this thesis are the first to show a strong correlation between the duration of specific arterial pressure responses during cord occlusions and the grade of brain injury, accounting for approximately 90% of the variability seen in the severity of injury. The mechanism responsible for the improved ability of lactate measurement to predict fetal brain injury is unknown. It may be because fetal lactate levels are a more stable marker of anaerobic metabolism of glucose than fetal pH levels, which are influenced by both increasing levels of carbon dioxide and anaerobic metabolism of amino-acids and fatty acids. In addition fetal pH levels can be rapidly normalised through placental exchange of carbon dioxide whereas fetal lactate levels are slow to normalise across the placenta as they rely on facilitated diffusion.

Much previous work on air pollution epidemiology has studied end-stage outcomes such as mortality or severe ill health warranting emergency admission, often based on clinical criteria prone to misclassification, and usually without accompanying study of the mediating mechanisms. Therefore this work has three specific objectives: firstly, to assess the effects of short-term exposure to particles and gases on acute coronary syndrome (ACS), by measuring the levels of cardiac troponin T (cTnT), a highly sensitive and specific marker of myocardial damage in patients admitted to hospital for chest pain of myocardial origin; secondly, to investigate the effects of short-term changes in ambient air pollution on the occurrence of transient ischaemic attacks (TIA); finally, to investigate the effects of ambient and personal exposure to air pollutants on a range of mediators or markers in a putative susceptible population. Two case-crossover studies were conducted to study the association between short-term changes in air pollutants and ischaemic cardiac events and TIA. Hospital data on admissions were analysed for actual or suspected ischaemic events and the associated cTnT levels were obtained. For the TIA project, data on 709 subjects were obtained from five TIA centres clustered around Manchester and Liverpool. In the third project a panel of 35 type 2 diabetes mellitus patients were prospectively followed fortnightly for a total of four visits. At each visit blood was collected to measure markers of inflammation, coagulation and endothelial function. In all three projects ambient air pollution data were obtained from background monitoring networks and in the third project personal exposure to PM2.5 was measured. Project 1: Of 28,622 admissions, 17.5% were ACS with myocyte necrosis (cTnT 0.03-1ng/ml) and 1004 (3.5%) were cases of myocardial infarction (cTnT ≥ 1 ng/ml). Both particulate and gaseous pollutants were associated with admission for ACS. The two largest effects per interquartile increase of exposure were observed with PM10 with ORof 1.14 (95% CI: 1.05-1.24) and with SO2, OR 1.11 (95% CI: 1.00-1.23). Associations between pollution and ACS admissions were the strongest for women, those above the age of 65 years and in the cooler season. Project 2: In the Manchester dataset, exposure to nitric oxide (NO) was associated with occurrence of TIA, while no effect was observed for Liverpool data. Subgroup analysis reveals that CO, NO and NO2 were more strongly related to the occurrence of TIA in participants above the age of 65 years and male patients. Project 3: No consistent association was observed between measured biomarkers and air pollutants using exposure data from ambient monitoring stations. In contrast, significant association between personal PM2.5 and interleukin-6 (IL-6) was observed. Similarly, personal PM2.5 had large but non-significant positive associations with high sensitivity C-reactive protein and fibrinogen. The results of this study reveal that short-term changes in particulate and gaseous pollution are related to the risk of admission for ACS as demonstrated by a specific marker hitherto not used for this purpose. It provides limited evidence for an association between changes in ambient NO concentration (which may have been a surrogate for another pollutant), and the occurrence of TIA, which had not previously been studied as an air pollution outcome, and increase in IL-6, a major pro-inflammatory marker. The IL-6 response to personal PM2.5 provides evidence in support of the link between ambient levels of particles/gases and cardiopulmonary morbidity and mortality.

M.Tech. (Chiropractic) / Purpose: Patients presenting with mechanical cervical spine pain demonstrate myofascial trigger points of the surrounding cervical spine musculature (De Las Penas, Alonso-Blanco, Alguacil-Diego and Miangolarra-Page, 2006). Myofascial trigger points, from specifically the cervical spine musculature, have been seen to be involved to a large extent with not only the local mechanical cervical spine pain but also the accompanying referred pain patterns and symptoms (De Las Penas, Alonso-Blanco and Miangolarra-Page, 2007). The purpose of this study is to compare the efficacy of ischaemic compression and laser therapy respectively, applied to an active myofascial trigger point in participants with acute mechanical cervical spine pain associated with an active trapezius myofascial trigger point TP1, with regards to pain, activities of daily living, pressure pain threshold and cervical spine range of motion. Method: This study consisted of two groups, the ischaemic compression group with fifteen participants and the laser group with fifteen participants. The participants were between the ages of eighteen and forty-five years of age. Prior to becoming a participant of this study, individuals were assessed according to the inclusion and exclusion criteria, a clinical case history, physical examination, cervical spine regional examination and upper trapezius muscle palpation to assess for an active trapezius myofascial trigger point 1. Treatment was applied to the active trapezius myofascial trigger point 1 only, from which the subjective and objective results were based. Procedure: Each participant was treated six times over a period of two consecutive weeks. Prior to initiation of the treatment, each participant was requested to complete the Vernon-Mior Neck Pain and Disability Index questionnaire and the Visual Analogue Scale. Algometer readings were obtained over the trapezius myofascial trigger point 1, bilaterally. The Cervical Range of Motion (CROM) goniometer was used to obtain numerical values for the participant’s active cervical spine ranges of motion: flexion, extension, lateral flexion, and rotation. Ischaemic compression and laser therapy, group 1 and group 2 respectively, then each received treatment of the active trapezius myofascial trigger point 1, for a total of six treatment sessions. Both subjective and objective data readings were obtained before the 1st, 4th, and at the 7th final consultation.

Background: South Africa aims to end all preventable deaths of children under the age of five as part of their commitment to the Sustainable Development Goals. More than half of these mortalities occur in the neonatal period with perinatal asphyxia as one of the leading causes. This study investigated and identified the characteristics of perinatal asphyxia and its contributing factors at a district hospital in Cape Town. Methods: A retrospective descriptive case series was performed and included all suspected cases of perinatal asphyxia referred from Mitchells Plain District Hospital (MPH)) to a specialised centre in the years 2016-2018. A data collection tool was used to extract information. Data was processed with SPSS to produce descriptive statistics and to investigate associations between variables using the Chi-square tests. Results: The study included 29 cases of suspected perinatal asphyxia. Ten (34.5%) had abnormal amplitude Electroencephalograms (aEEG's) indicative of Hypoxic Ischaemic Encephalopathy (HIE) and four (13.8%) demised before day seven of life. Non-operative deliveries (p=0.005), lack of a doctor at the time of delivery (p=0.004) and neonatal chest compressions (p=0.044) were associated with abnormal aEEG's. Babies with Thompson score of equal to or more than 12 (p=0.006), neonatal seizures (p=0.036) and delayed arrival at referral hospital (p=0.005) were associated with abnormal aEEG findings. Mortality was associated with Thompson score ≥12 (p=0.007) and the need for neonatal intubation at delivery (p=0.016). Conclusions: Significant reversable factors were identified in the peri-and postpartum periods. More capacitated staff would have the greatest impact on outcomes. The profile of HIE is exceedingly complex and challenges the resources and services of district level of care. Therefore, these factors should be targeted for future development and investment to improve outcomes from district hospitals.

Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine. Stroke is the leading cause of disability worldwide. HSPA12B, a heat-shock protein recently identified expression specifically in endothelial cells, is able to promote angiogenesis. Here, we have investigated its effects on functional recovery at chronic phase of ischaemic stroke. Ischaemic stroke was induced by 60 min. of middle cerebral artery occlusion in transgenic mice with overexpression of HSPA12B (HSPA12B Tg) and wild-type littermates (WT). HSPA12B Tg mice demonstrated a significant higher survival rate than WT mice within 28 days post-stroke. Significant improved neurological functions, increased spontaneous locomotor activity and decreased anxiety were detected inHSPA12B Tg mice compared with WT controls within 21 days post-stroke. Stroke-induced hippocampal degeneration was attenuated in HSPA12B Tg mice examined at day 28 post-stroke. Interestingly, HSPA12B Tg mice showed enhanced peri-infarct angiogenesis (examined 28 days post-stroke) and hippocampal neurogenesis (examined 7 days post-stroke), respectively, compared to WT mice. The stroke-induced eNOS phosphorylation and TGF-β1 expression were augmented in HSPA12B Tg mice. However, administration with eNOS inhibitor L-NAME diminished the HSPA12B-induced protection in neurological functional recovery and mice survival post-stroke. The data suggest that HSPA12B promoted functional recovery and survival after stroke in an eNOS-dependent mechanism. Targeting HSPA12B expression may have a therapeutic potential for the stroke-evoked functional disability and mortality.

Isolated adult rat myocytes were subjected to 180 min of metabolic inhibition or incubated in ischaemic pellets, in the presence and absence of 10 μm okadaic acid (OA) or calyculin A (CL-A). Contracture and viability was determined by light microscopic analysis of trypan blue-stained preparations and ATP levels by HPLC. Osmotic fragility was assessed by brief hypotonic swelling of cells in 170 or 85 mOsm media prior to determination of viability. Neither drug significantly affected the relatively rapid rates of contracture of myocytes during metabolic inhibition, and both afforded significant protection from development of trypan blue permeability and osmotic fragility. Both OA and CL-A significantly accelerated the rates of contracture and ATP depletion of myocytes during ischaemic incubations. Despite an enhanced rate of ATP depletion, which would be expected to accelerate development of injury, neither drug accelerated development of loss of viability or development of osmotic fragility as measured by 170 mOsm swelling. Mathematical compensation for different rates of ATP depletion confirmed that a protective effect of the drugs, during ischaemic incubation, was masked by their enhancement of the rate of injury, following swelling at 170 mOsm. When the effects of CL-A on ischaemic cells were examined at 85 mOsm, a more stringent test for osmotic fragility, protection was found without compensation for differing rates of ATP depletion. A dose/response curve for CL-A showed some effect at 100 nm and a nearly full effect during metabolic inhibition at 1 μm concentrations. It is concluded that protein phosphatase inhibitors reduce the rates of development of osmotic fragility of metabolically inhibited cells and reduces the rate of injury relative to the rate of ATP depletion of ischaemic cardiomyocytes. Phosphorylation mechanisms may be important to development of irreversible myocardial cell injury.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Please see fulltext for abstract. / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Introduction: Coronary heart disease (CHD) is the leading cause of death worldwide with 3.8 million men and 3.4 million women dying globally each year. Although existing myocardial reperfusion strategies such as thrombolysis and percutaneous coronary intervention (PCI), if applied in a timely manner, limit myocardial infarct size, the mortality and morbidity remains significantly high. Ischaemic preconditioning (IPC) may offer the potential to attenuate myocardial ischaemia/reperfusion injury through cardioprotective signaling pathways which is recruited at the time of myocardial reperfusion, thereby improving clinical outcomes in patients with coronary artery disease. Ischaemic preconditioning is a phenomenon whereby short intermittent episodes of coronary occlusion followed by reperfusion protect the myocardium against a subsequent period of sustained ischaemia. This protection is reflected in the limitation of infarct size and improved functional recovery of the ischaemic heart during reperfusion. Despite intensive research efforts, the promise of an effective cardioprotective strategy using the endogenous protective mechanisms of the heart which underlies IPC, has not yet been materialized. Although progress has been made in terms of signaling mechanisms in the preconditioned heart, the identification of the myocardial reperfusion phase as the critical “window” for cardioprotection, requires the elucidation of the signal transduction pathways during the reperfusion phase after IPC. In view of the above, the aims of the present study were to investigate: i. the involvement of the RISK pathway and p38 MAP kinase pathway in IPC during early and late reperfusion ii. the involvement of heat shock protein-27 (HSP-27), heat shock protein-70 (HSP-70), GSK-3β, CAMKII, AMPK and the transcription factor CREB in the context of IPC during early reperfusion iii. the involvement of autophagy and apoptosis during early and late reperfusion after IPC iv. the correlation of the protein kinases with the hemodynamic parameters of the heart v. the mechanism of IPC by means of two-dimensional (2D) proteomics Methods: The isolated perfused working rat heart model was used with functional recovery as end-point. Hearts were preconditioned (IPC) for 3x5 min global ischaemia, alternated with 5 min reperfusion. Hearts were subjected to 25 min sustained global ischaemia, followed by 5, 10, 15 or 30 min reperfusion when hearts were snap-frozen for western blotting analysis. Alternatively, hearts were reperfused for 30 min to record hemodynamic parameters and measure functional recovery. Non-preconditioned (Non-IPC) hearts were stabilized for 30 min and subjected to 25 min sustained global ischaemia followed by 5, 10, 15 or 30 min reperfusion when hearts were snap-frozen. Alternatively Non-IPC hearts were reperfused for 30 min to serve as control for the 30 min reperfused IPC group. Activation of the protein kinases was determined by western blotting analysis. For the proteomic study mitochondrial and cytosolic proteins were isolated from heart tissue and separated in the first dimension by isoelectric focusing, followed by separation in the second dimension by two dimensional gel electrophoresis. The PD Quest software programme was used to identify significantly expressed protein spots. Protein spots of interest were excised and subjected to in-gel digestion and the resulting peptides were analysed by mass spectrometry. Proteins were identified by Mascot and the Swiss Prot database. Results: Western blotting analysis demonstrated that the RISK pathway and p38 MAPK are activated very early in reperfusion, but the activation is not sustained during the reperfusion period. Autophagy is also upregulated during this early reperfusion phase; it is attenuated in the middle reperfusion phase and increase for a second peak of upregulation in the late reperfusion phase. In addition, we identified CAMKII as a novel marker of functional recovery in IPC after reperfusion. The proteomic analysis identified twenty differentially expressed mitochondrial and thirty six differentially expressed cytosolic proteins between Non-IPC and IPC hearts. Functions ascribed to the majority of these individual proteins were directly related to cardiac metabolism. Conclusion: Activation of the majority of the protein kinases investigated in the present study is associated with the hemodynamic parameters of the heart instead of functional recovery. Results indicated that the variable signaling patterns could be attributed to differences in heart rate and the effect thereof (ejection fraction, minimum and maximum rate of contraction), as a result of sympathetic stimulation due to psychological stress in the animals before slaughtering. Proteomics results demonstrated that IPC hearts which failed after ischaemia /reperfusion are metabolically compromised and “worse off” compared to non-IPC hearts. / AFRIKAANSE OPSOMMING: Inleiding: Koronêre hartsiekte is die vernaamste oorsaak van sterftes wêreldwyd met 3.8 miljoen mans en 3.4 miljoen vrouens wat jaarliks sterf. Alhoewel bestaande miokardiale herperfusie strategieë soos trombolise en perkutane koronêre intervensie (PKI), wanneer betyds toegepas, miokardiale infarktgrootte beperk, bly mortaliteit en morbiditeit steeds hoog. Isgemiese prekondisionering (IPK) beskik oor die potensiaal om miokariale isgemie/herperfusie skade te verminder deur beskermende seinoordragpaaie tydens miokardiale herperfusie te aktiveer en sodoende die pasiënte wat aan koronêre arterie siekte ly, se prognose te verbeter. Isgemiese prekondisionering verwys na die verskynsel waartydens kort episodes van isgemie opgevolg deur herperfusie, die miokardium teen ‘n daaropvolgende langdurige isgemiese insident beskerm. Hierdie beskerming word gereflekteer in die beperking van infarktgrootte en verbeterde funksionele herstel van die isgemiese hart tydens herperfusie. Ten spyte van intensiewe navorsingspogings is die presiese meganisme van endogene beskerming tydens IPK nog nie ten volle ontrafel nie. Die identifisering van die miokardiale herperfusie fase se kritiese “vensterperiode” van beskerming, noodsaak ‘n volledige analise van die seinoordragpaaie wat geaktiveer word tydens die herperfusie fase na IPK. In die lig van bogenoemde, was die doel van die huidige studie om die volgende te ondersoek: i. die betrokkenheid van die RISK seinoordragpad en p38 MAP kinase tydens vroeë en laat herperfusie na IPK ii. die betrokkenheid van “heat shock protein-27” (HSP-27), “heat shock protein- 70” (HSP-70), GSK -3β, CAMKII, AMPK en die transkripsie faktor, CREB, in die konteks van IPK tydens vroeë herperfusie iii. die betrokkenheid van outofagie en apoptose tydens vroeë en laat herperfusie na IPK iv. die korrelasie van die proteïenkinases met die hemodinamiese parameters van die hart v. die meganisme van IPK deur middel van twee dimensionele proteomika Metodes: Die geïsoleerde werkende rothart model, met funksionele herstel as eindpunt, is gebruik. Harte is geprekondisioneer (IPK) met 3x5 min globale isgemie, afgewissel met 5 min herperfusie. Daarna is harte blootgestel aan 25 min volgehoue globale isgemie, gevolg deur 5, 10, 15 of 30 min herperfusie, waartydens harte gevriesklamp is. Alternatiewelik, is harte blootgestel aan 30 min herperfusie ten einde funksionele herstel te meet en hemodinamiese parameters te registreer. Nie-geprekondisioneerde (Non-IPK) harte is gestabiliseer vir 30 min, waarna dit onderwerp is aan 25 min volgehoue globale isgemie, gevolg deur 5, 10, 15 of 30 min herperfusie, waartydens harte gevriesklamp is vir westelike klad analise. Alternatiewelik, is Non-IPK harte onderwerp aan 30 min herperfusie om te dien as kontrole vir die 30 min IPK groep. Aktivering van die proteïenkinases is bepaal deur westelike klad analise. Vir die proteomiese studie, is onderskeidelik mitokondriale en sitosoliese proteïene geïsoleer en geskei in die eerste dimensie met behulp van isoelektriese fokusering, gevolg deur skeiding in die tweede dimensie met behulp van twee dimensionele gel elektroforese. Die PDQuest sagteware program is gebruik om proteïenkolle te identifiseer wat statisties beduidende verskille toon. Proteïenkolle van belang is uitgesny en onderwerp aan in-gel tripsinering en die peptiede wat sodoende verkry is, is deur middel van massa spektrometrie geanaliseer. Proteïene is geïdentifiseer deur Mascot en die Swiss Prot databasis. Resultate: Westelike klad analise het aangetoon dat die RISK pad en p38 MAPK geaktiveer is tydens vroeë herperfusie, maar die aktivering word nie volgehou tydens die hele herperfusie periode nie. Outofagie word gestimuleer tydens die vroeë herperfusie fase; dit word onderdruk in die middel herperfusie fase en bereik ‘n tweede piek van stimulering in die laat herperfusie fase. Die proteomiese analise het onderskeidelik twintig differensieel gereguleerde mitokondriale proteïene en ses en dertig differensieel gereguleerde sitosoliese proteïene geïdentifiseer tussen Non-IPK en IPK. Die grootste persentasie van hierdie proteïene is direk betrokke by miokardiale energie metabolisme. CAMKII is geidentifiseer as ‘n unieke merker van funksionele herstel in IPK tydens reperfusie. Gevolgtrekking: Aktivering van die meeste van die proteïenkinases wat ondersoek is in die huidige studie, is geassosieer met die hemodinamiese parameters van die hart, in plaas van funksionele herstel. Die resultate het aangetoon dat die varierende patrone van kinase aktivering toegeskryf kan word word aan verskille in harttempo en die effek daarvan (ejeksie fraksie, minimum en maksimum tempo van kontraksie), as gevolg van simpatiese stimulasie toegeskryf aan sielkundige stres in die diere voor slagting. Proteomiese analise het getoon dat IPK harte wat faal na isgemie/reperfusie metabolies gekompromiseer is en “slegter daaraan toe” is, in vergelyking met Non-IPK harte.