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<p>In 101 patients with ST-elevation myocardial infarction treated with streptokinase the additional effects of lmw-heparin (dalteparin) were investigated. The prognostic value of troponin-T (TnT) was elucidated and the development of myocardial damage was investigated with Positron Emission Tomography (PET).</p><p>Dalteparin tended to provide a higher rate of TIMI grade 3 flow in the infarct-related artery at 24 h compared to placebo. In patients with signs of early reperfusion there was a higher rate of TIMI grade 3 flow in the dalteparin group compared to placebo. There were significantly fewer patients with ischemic episodes at 6-24 h in the dalteparin compared to placebo group.</p><p>The increase in coagulation activity was attenuated in the dalteparin group. There was a tendency to more ischemic episodes and lower frequency of TIMI grade 3 flow in patients with persistent elevation of coagulation activity at 18 h. Among deceased patients the coagulation activity was significantly higher than in survivors. </p><p>The association between elevated TnT on admission and long-term mortality might be explained by longer delay, episodes of chest pain during the last 24 h, less non-invasive signs of reperfusion at 90 minutes, and lower patency in the infarct-related artery at 24 h. </p><p>Eight patients were investigated with PET at 3h, 24 h and after 3 weeks. PET outlines the infarct region with reduced perfusion and metabolism. The oxidative metabolism in the infarct region at 3 h correlated with the water-Perfusable Tissue Fraction (PTF) and its improvement over time.</p><p>Dalteparin seems to improve maintenance of coronary patency, which can be explained by attenuation of the increased coagulation activity. Elevated TnT level on admission is associated with a worse outcome, which can partly be explained by less successful fibrinolytic treatment. PET investigations might to be a useful method in future trials evaluating new agents in the treatment of acute myocardial infarction.</p>

In 101 patients with ST-elevation myocardial infarction treated with streptokinase the additional effects of lmw-heparin (dalteparin) were investigated. The prognostic value of troponin-T (TnT) was elucidated and the development of myocardial damage was investigated with Positron Emission Tomography (PET). Dalteparin tended to provide a higher rate of TIMI grade 3 flow in the infarct-related artery at 24 h compared to placebo. In patients with signs of early reperfusion there was a higher rate of TIMI grade 3 flow in the dalteparin group compared to placebo. There were significantly fewer patients with ischemic episodes at 6-24 h in the dalteparin compared to placebo group. The increase in coagulation activity was attenuated in the dalteparin group. There was a tendency to more ischemic episodes and lower frequency of TIMI grade 3 flow in patients with persistent elevation of coagulation activity at 18 h. Among deceased patients the coagulation activity was significantly higher than in survivors. The association between elevated TnT on admission and long-term mortality might be explained by longer delay, episodes of chest pain during the last 24 h, less non-invasive signs of reperfusion at 90 minutes, and lower patency in the infarct-related artery at 24 h. Eight patients were investigated with PET at 3h, 24 h and after 3 weeks. PET outlines the infarct region with reduced perfusion and metabolism. The oxidative metabolism in the infarct region at 3 h correlated with the water-Perfusable Tissue Fraction (PTF) and its improvement over time. Dalteparin seems to improve maintenance of coronary patency, which can be explained by attenuation of the increased coagulation activity. Elevated TnT level on admission is associated with a worse outcome, which can partly be explained by less successful fibrinolytic treatment. PET investigations might to be a useful method in future trials evaluating new agents in the treatment of acute myocardial infarction.

Foraging behaviour in Drosophila melanogaster larvae is influenced by natural allelic variation in the foraging (for) gene that encodes a cyclic GMP – dependent protein Kinase (PKG), such that rovers (forR) traverse greater distances while foraging than sitters (fors). Foraging behaviour is also influenced by natural allelic variation in the wings up A (wupA) gene that encodes the Troponin-I protein (TnI). Specifically, wupAlow allele suppresses the dominance of the forR allele, turning rovers into sitters. The dominance of the natural wupA alleles and their interactions with allelic combinations in for has not been characterized. I conducted various crosses and found that wupA alleles exhibit incomplete dominance. More importantly, I found that allelic combinations of wupA and for gave rise to a range in larval foraging behaviour. In this study, I propose that this gradient effect in foraging behaviour is due to variation in levels of PKG activity and TnI phosphorylation potential.

Foraging behaviour in Drosophila melanogaster larvae is influenced by natural allelic variation in the foraging (for) gene that encodes a cyclic GMP – dependent protein Kinase (PKG), such that rovers (forR) traverse greater distances while foraging than sitters (fors). Foraging behaviour is also influenced by natural allelic variation in the wings up A (wupA) gene that encodes the Troponin-I protein (TnI). Specifically, wupAlow allele suppresses the dominance of the forR allele, turning rovers into sitters. The dominance of the natural wupA alleles and their interactions with allelic combinations in for has not been characterized. I conducted various crosses and found that wupA alleles exhibit incomplete dominance. More importantly, I found that allelic combinations of wupA and for gave rise to a range in larval foraging behaviour. In this study, I propose that this gradient effect in foraging behaviour is due to variation in levels of PKG activity and TnI phosphorylation potential.

Atrial fibrillation (AF) confers an independent increased risk of stroke and death. The stroke risk is very heterogeneous and current risk stratification models based on clinical variables, such as the CHADS2 and CHA2DS2VASc score, only offer a modest discriminating value. The aims of this thesis were to study cardiac biomarkers, cardiac troponin and natriuretic peptides e.g. N-terminal prohormone-B-type natriuretic peptide (NT-proBNP), and describe levels in AF patients, investigate the association with stroke or systemic embolism, cardiovascular event, major bleeding and mortality, and to assess how levels of cardiac biomarkers change over time. Cardiac troponin was analyzed with contemporary assays and high sensitivity assays. The study populations consisted of patients with atrial fibrillation and one risk factor for stroke included in the RE-LY (n=6189) and the ARISTOTLE (n=14892) biomarker substudies. Median follow-up time was 2.2 years and 1.9 years, respectively. In a subset of participants (n=2514) data from repeated measurements was available at three months. Cardiac troponin was detectable in 57.0% with the contemporary assay and 99.4% with the high sensitivity assay. NT-proBNP was elevated in approximately three quarters of the participants. In Cox models adjusted for established risk factors the cardiac biomarkers levels was independently associated with stroke or systemic embolism, cardiovascular events, and mortality. Only cardiac troponin was associated with major bleeding. In ROC analyses the prediction of stroke or systemic embolism, cardiovascular events, and mortality increased significantly by addition of cardiac troponin or NT-proBNP to the models. Persistent detectable cardiac troponin (contemporary assay) and elevated NT-proBNP levels were found in a large number of participants. Persistent detectable or elevated levels conferred significantly higher risk for stroke or systemic embolism, cardiovascular events, and mortality. By using both cardiac biomarkers simultaneously the risk stratification improved even further for all outcomes. In conclusion the analyses for the first time display that elevation of troponin I and NT-proBNP are common in patients with AF and independently related to increased risks of stroke, cardiovascular events and mortality. Persistent elevation of troponin and NT-proBNP indicate a worse prognosis than transient elevations or no elevations of either marker. The cardiac biomarkers added substantial improvements to existing risk stratification models.

I investigated SL trans-splicing in the troponin I gene of Ciona intestinalis. Experimental mutation of the AG dinucleotide adjacent to the natural trans-splice acceptor site (-64) in CiTnI/nuclacZ constructs eliminated trans-splicing to that site in Ciona embryos but activated trans-splicing at cryptic acceptor sites at -76 and -39, adjacent to the nearest AG dinucleotides. However, not all AG dinucleotides specify cryptic acceptor sites because outron internal deletions or 3'truncation mutants were trans-spliced at a far-upstream AG-adjacent cryptic site (-346), leaving many AGs in the retained outron segments. Thus, additional sequence elements that are present only in the -346 and -76/-64/-39 regions are required for cryptic acceptor activity. All mutant constructs generated detectable beta-gal enzyme expression, although the mutant with the longest retained-outron segment appeared less active. Therefore, mRNA accumulation and translation do not require trans-splicing to the natural acceptor site, although they may be facilitated by the normal removal of the outron during trans-splicing.

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 4 uppsatser.

BACKGROUND: Cardiovascular disease, principally manifest as myocardial infarction or stroke, is the dominant cause of death worldwide and despite therapeutic advances, the global burden of these conditions continues to increase. In order to address this ongoing disease burden, there is a clear need to more effectively target the use of existing and novel diagnostic investigations and medical therapies. Emerging cardiovascular biomarkers include the biochemical, such as high-sensitivity cardiac troponin, and the radiological, such as computed tomography coronary angiography (CTCA) and 18Ffluoride positron emission tomography (PET). Cardiac troponins can now be reliably quantified in clinically stable or asymptomatic populations and provide information about myocardial pathophysiology, whilst CTCA can non-invasively quantify atherosclerotic burden and 18F-fluoride PET imaging offers insight into plaque vulnerability. Improved targeting of diagnostic investigations requires more reliable estimation of pre-test probability of coronary disease whilst optimizing the use of pharmacological or interventional treatments requires more accurate prognostic stratification. Achieving both objectives in an equitable manner across all population groups will depend upon updated clinical guidelines containing improved risk models and enhanced management pathways. The objective of this thesis was to investigate the potential clinical benefit of novel approaches to the diagnostic and prognostic assessment of coronary heart disease. EVALUATION OF THE 2016 NATIONAL INSTITUTE FOR HEALTH AND CARE EXCELLENCE (NICE) GUIDANCE ON THE ASSESSMENT OF SUSPECTED STABLE ANGINA. A post-hoc analysis was undertaken of the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial of 4,146 participants with suspected angina randomised to assessment with computed tomography coronary angiography or standard care. Patients were dichotomised according to guideline definitions into groups representing possible angina and non-anginal presentations. The primary (diagnostic) endpoint was diagnostic certainty of angina at 6 weeks and the prognostic endpoint comprised fatal and non-fatal myocardial infarction. In 3,770 eligible participants, CTCA increased diagnostic certainty more in those with possible angina (relative risk [RR] 2.22 (95% CI 1.91-2.60), p < 0.001) than those with non-anginal symptoms (RR 1.30 (1.11-1.53), p=0.002; pinteraction < 0.001). In the possible angina cohort, CTCA did not change rates of invasive angiography (p=0.481) but markedly reduced rates of normal coronary angiography (hazard ratio [HR] 0.32 (0.19-0.52), p < 0.001). In the non-anginal cohort, rates of invasive angiography increased (HR 1.82 (1.13-2.92), p=0.014) without reducing rates of normal coronary angiography (HR 0.78 (0.30-2.05), p=0.622). At 3.2 years of follow-up, fatal or nonfatal MI was reduced in patients with possible angina (3.2% to 1.9%; HR 0.58 (0.34- 0.99), p=0.045) but not in those with non-anginal symptoms (HR 0.65 (0.25-1.69), p=0.379). Overall the updated NICE guidance on patient assessment maximises the benefits of CTCA with respect to diagnostic certainty, the use of invasive coronary angiography, and reductions in fatal and non-fatal myocardial infarction. Patients with non-anginal chest pain derive minimal benefit from CTCA, which instead increases rates of invasive investigation. EXTERNAL VALIDATION OF THE PROSPECTIVE MULTICENTER IMAGING STUDY FOR EVALUATION OF CHEST PAIN (PROMISE) TOOL FOR DETERMINING MINIMAL-RISK OF CORONARY ARTERY DISEASE. The PROspective Multicenter Imaging Study for Evaluation of chest pain (PROMISE) minimal-risk tool was recently developed to identify patients with suspected stable angina at very low risk of coronary artery disease and clinical events. The external validity of this tool was investigated within the context of the Scottish Computed Tomography of the HEART multicenter randomised controlled trial of patients with suspected stable angina due to coronary artery disease. Model discrimination and calibration was determined amongst 1,764 patients in whom complete CCTA data were available and compared with the European Society of Cardiology guideline-endorsed Coronary Artery Disease Consortium (CADC) risk score. The PROMISE minimal-risk tool improved discrimination compared with the CADC model (c-statistic 0.785 vs 0.730, p < 0.001) and was improved further following re-estimation of covariate coefficients (c-statistic 0.805, p < 0.001). Model calibration was initially poor (c2 197.6, Hosmer-Lemeshow [HL] p < 0.001), with significant overestimation of probability of minimal risk, but improved significantly following revision of the PROMISE minimal-risk intercept and covariate coefficients (c2 5.6, HL p=0.692). HIGH-SENSITIVITY CARDIAC TROPONIN I IN THE DIAGNOSIS OF STABLE CORONARY ARTERY DISEASE In a pre-specified sub-study of the Scottish COmputed Tomography of the Heart trial, plasma cardiac troponin was measured using a high-sensitivity single molecule counting assay in 943 adults with suspected stable angina who had undergone coronary computed tomography angiography. Rates of obstructive coronary artery disease were compared with the pre-test probability determined by the European Society of Cardiology Coronary Artery Disease Consortium risk model with and without cardiac troponin concentrations. External validation was undertaken in an independent study population from Denmark comprising 487 patients with suspected stable angina. Higher cardiac troponin concentrations were associated with obstructive coronary artery disease with a 5-fold increase across quintiles (9 to 48%, p < 0.001) independent of known cardiovascular risk factors (odds ratio [OR] 1.35 [95% confidence interval (CI) 1.25-1.46] per doubling of troponin). Cardiac troponin concentrations improved the discrimination of the ESC model for identifying obstructive coronary artery disease (c-statistic 0.785 to 0.800, p=0.003) and improved classification into ESCrecommended categories of clinical risk (net reclassification improvement 0.143 [95% CI, 0.093-0.193]). The revised model achieved similar improvements in discrimination and net reclassification when applied in the external validation cohort. HIGH-SENSITIVITY CARDIAC TROPONIN I IN CARDIOVASCULAR RISK STRATIFICATION OF PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE AND HEIGHTENED CARDIOVASCULAR RISK. The association between plasma high-sensitivity cardiac troponin I concentration and cardiovascular events in patients with chronic obstructive pulmonary disease and heightened cardiovascular risk was examined within the context of a double-blind randomised controlled trial of inhaled corticosteroids and bronchodilators (1 placebo arm and 3 different treatment arms). Plasma cardiac troponin I concentrations were measured with a high-sensitivity assay in a subgroup of 1,599 patients. The cardiovascular endpoint was a composite of cardiovascular death, myocardial infarction, stroke, unstable angina and transient ischaemic attack during follow-up of 1.5 years. Baseline plasma cardiac troponin I concentrations were above the lower limit of detection (1.0 ng/L) in 1,559 (97.5%) patients and were unaffected by inhaled therapies at 3 months (p > 0.05 for all). Compared with the lowest tertile (cardiac troponin I ≤3.0 ng/L), patients in the highest tertile (≥ 5.5 ng/L) were at greater risk of cardiovascular events (hazard ratio 3.0, 95% confidence interval 1.5 to 6.2, p=0.002) and cardiovascular death (hazard ratio 9.6, 95% confidence interval 2.6 to 35.6, p < 0.001) after adjustment for cardiovascular risk factors. There were no differences in COPD exacerbations between tertiles even after adjustment (p > 0.05). / REPRODUCIBILITY OF CORONARY 18F-FLUORIDE PET-CT IMAGING The inter-observer and scan-rescan reproducibility of coronary 18F-fluoride PET-CT imaging was investigated in 20 patients with clinically stable but high risk multi-vessel coronary artery disease who underwent repeated 18F-fluoride PET-CT scans 11.5±4.5 days apart. Scan analysis using the currently accepted approach of normalisation to a referent coronary segment (TBRREFERENT) identified 10 (50%) patients with evidence of focal coronary 18F-fluoride uptake and demonstrated moderate agreement across observers on a per-patient level (k = 0.56). This was similar to the level of agreement achieved with visual assessment alone (k = 0.64). Reproducibility was improved by semi-quantitative reporting combining visual assessment with a threshold uptake value for determining the presence of tracer uptake (k = 0.84). Using the optimised approach achieved excellent agreement on overall segmental uptake counts (intra-class correlation = 0.97). CONCLUSION: Cardiovascular diagnostic and prognostic assessments represent a complex endeavour and established tools for risk prediction can demonstrate suboptimal predictive accuracy when evaluated in patient cohorts that are independent of the population used for model derivation.

A insuficiência cardíaca é a doença crônica com maior impacto na sobrevida e qualidade de vida dos pacientes. Apesar do constante desenvolvimento de novas estratégias de tratamento, esta doença continua atingindo altos índices de mortalidade. O coração adulto tem capacidade de regeneração limitada e há grande evidência experimental de que os transplantes de células-tronco poderiam ser uma abordagem eficiente na recuperação do miocárdio lesado. Contudo, a maioria dos estudos são realizados em cardiomiopatias isquêmicas, existindo poucos estudos na cardiomiopatia dilatada (CMD). Em função disto, este trabalho foi realizado com o objetivo de avaliar a regeneração do miocárdio em coelhos com CMD induzida pela doxorrubicina, por meio do uso de células-tronco mesenquimais (MSC) obtidas de tecido adiposo, associadas ou não com plasma rico em plaquetas (PRP). Foram utilizadas 40 coelhas, Nova Zelândia, e um coelho macho doador das MSCs derivadas do tecido adiposo. As coelhas foram divididas em dois grupos: CMD induzida pela doxorrubicina e o grupo saudável. Cada grupo foi subdividido conforme o tratamento recebido: solução fisiológica, MCSs, PRP e MSCs associadas ao PRP. Os subgrupos receberam o tratamento por injeção diretamente no miocárdio no ventrículo esquerdo mediante toracoscopia vídeo assistida. Os coelhos foram avaliados por exames de ecocardiograma, eletrocardiograma, troponina I, no dia da chegada, após a indução da CMD e 15 dias após o recebimento das terapias. Nesta última avaliação, foi realizada a eutanásia e coletado o coração para análise histológica. Foi observado que após a indução, a troponina I se elevou, o segmento QRS visto no eletrocardiograma, aumentou e, no ecocardiograma, as frações de ejeção (FE) e encurtamento (FS) diminuíram e o diâmetro sistólico do ventrículo esquerdo (VEs) aumentou, em todos os animais avaliados. Após os tratamentos, o subgrupo MSCs obtiveram os melhores resultados em todas as análises citadas. Houve menor elevação da troponina I, o segmento QRS diminuiu, as FS e FE aumentaram e o VEs diminuiu. No exame histopatógico, analisado pela coloração de hematoxicilina-eosina, constatou-se que o subgrupo MSCs apresentou menos lesões, e nos subgrupos MSCs associadas com PRP, solução fisiológica e PRP as lesões aumentaram gradualmente, respectivamente. Os resultados sugerem que o uso das MSCs melhoraram a função cardíaca em coelhos com cardiomiopatia dilatada e que há necessidade de mais estudos no uso de PRP no miocárdio. / Heart failure is a chronic disease with major impact on survival and quality of patient’s life. Despite the constant development of new treatment strategies, this disease still affects high mortality rates. The adult heart has limited ability to regenerate and there is experimental evidence that large transplants of stem cells could be an effective approach in the recovery of injured myocardium. However, most studies are performed in ischemic cardiomyopathy, there are few studies in dilated cardiomyopathy. Because of this, this study aimed at evaluating the regeneration of the myocardium in rabbits with dilated cardiomyopathy induced by doxorubicin through the use of mesenchymal stem cell (MSC) derived from adipose tissue, associated or not with platelet-rich plasma (PRP). 40 New Zealand rabbits were utilized and a male rabbit donor MSCs derived from adipose tissue. The rabbits were divided into two groups: dilated cardiomyopathy doxorubicin-induced and the healthy group. Each group was divided according to treatment received: saline, MSCs, PRP and MSCs associated with PRP. The subgroups receiving treatment through an injection directly into the myocardium of the left ventricle through video-assisted thoracoscopy. The rabbits were evaluated by echocardiogram, electrocardiogram, troponin I, on the day of arrival, after induction of dilated cardiomyopathy and 15 days after receipt of therapies. This last evaluation, euthanasia was performed and the hearts collected for histological analysis. It was observed that after induction the troponin I increased, the QRS segment, seen on the electrocardiogram, increased, and, in echocardiography, the ejection and shortening fractions decreased, and left ventricular systolic diameter increased in all animals evaluated. After treatments, the subgroup MSCs have the best results in all tests cited. There was a lower elevation of troponin I, decreased QRS segment, the ejection and shortening fractions increased and left ventricular systolic diameter decreased. On examination histologic, analyzed by hematoxylin-eosin staining, the subgroup found that MSCs had fewer injuries, and in the subgroups MSCs associated with PRP, PRP and saline lesions gradually increased, respectively. The results suggest that the use of MSCs improved cardiac function in rabbits with dilated cardiomyopathy and that there is need for more studies on the use of PRP in the myocardium.