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  • Aalto, Hannele (Helsingin yliopisto, 2007)
    Sepsis is associated with a systemic inflammatory response. It is characterised by an early proinflammatory response and followed by a state of immunosuppression. In order to improve the outcome of patients with infection and sepsis, novel therapies that influence the systemic inflammatory response are being developed and utilised. Thus, an accurate and early diagnosis of infection and evaluation of immune state are crucial. In this thesis, various markers of systemic inflammation were studied with respect to enhancing the diagnostics of infection and of predicting outcome in patients with suspected community-acquired infection. A total of 1092 acutely ill patients admitted to a university hospital medical emergency department were evaluated, and 531 patients with a suspicion of community-acquired infection were included for the analysis. Markers of systemic inflammation were determined from a blood sample obtained simultaneously with a blood culture sample on admission to hospital. Levels of phagocyte CD11b/CD18 and CD14 expression were measured by whole blood flow cytometry. Concentrations of soluble CD14, interleukin (IL)-8, and soluble IL-2 receptor α (sIL-2Rα) were determined by ELISA, those of sIL-2R, IL-6, and IL-8 by a chemiluminescent immunoassay, that of procalcitonin by immunoluminometric assay, and that of C-reactive protein by immunoturbidimetric assay. Clinical data were collected retrospectively from the medical records. No marker of systemic inflammation, neither CRP, PCT, IL-6, IL-8, nor sIL-2R predicted bacteraemia better than did the clinical signs of infection, i.e., the presence of infectious focus or fever or both. IL-6 and PCT had the highest positive likelihood ratios to identify patients with hidden community-acquired infection. However, the use of a single marker failed to detect all patients with infection. A combination of markers including a fast-responding reactant (CD11b expression), a later-peaking reactant (CRP), and a reactant originating from inflamed tissues (IL-8) detected all patients with infection. The majority of patients (86.5%) with possible but not verified infection showed levels exceeding at least one cut-off limit of combination, supporting the view that infection was the cause of their acute illness. The 28-day mortality of patients with community-acquired infection was low (3.4%). On admission to hospital, the low expression of cell-associated lipopolysaccharide receptor CD14 (mCD14) was predictive for 28-day mortality. In the patients with severe forms of community-acquired infection, namely pneumonia and sepsis, high levels of soluble CD14 alone did not predict mortality, but a high sCD14 level measured simultaneously with a low mCD14 raised the possibility of poor prognosis. In conclusion, to further enhance the diagnostics of hidden community-acquired infection, a combination of inflammatory markers is useful; 28-day mortality is associated with low levels of mCD14 expression at an early phase of the disease.
  • Parviainen, Ville (Helsingin yliopisto, 2014)
    The field of biological sciences has expanded enormously within the last few decades. Developments in techniques and instrumentation have allowed biologist to explore biological mechanisms in an unprecedented detail. One of the most evolved disciplines is the field of proteomics. In general, proteins function in many different biological roles. They serve as structural molecules, in signaling routes mediating information in the cell, in intra- and extracellular transport and trafficking as well as in numerous other cellular functions. The area of protein research entails the study of all things relating to proteins and their functions. These include cellular protein composition, expression changes, protein structure, post-translational modifications and protein-protein interactions. Mass spectrometry (MS) has become one of the key technologies in proteomic research. The relative ease of sample handling and automated MS machinery has made proteomic analysis relatively straightforward. Mass spectrometers work by measuring the weight of intact proteins or protein-derived peptides. Proteomic MS identification is usually done by fragmenting the proteins or peptides in the mass spectrometer and using the resulting mass spectral information in identification of peptide sequence. There are two main strategies of peptide sequence identification: database dependent and de novo identification. Database dependent algorithms utilize known sequence information stored in databases to decipher the peptide amino acid sequence of the MS-observed spectra and use that information to predict the protein from which the peptide is derived from. On the other hand de novo methods try to construct the peptide sequence solely based on the fragmentation patterns of the peptide. The completeness of sequence databases of many species and the speed and efficiency of the search engines have made the database dependent search as the main method in peptide and protein identification. The modern high resolution mass spectrometers along with ultra-performance liquid chromatography have enabled the detection of thousands of protein in one single MS run. This, together with advances in MS-based protein quantification has extended the use of mass spectrometers in discovery type biomarker search. Mass spectrometers are able to produce a large amount of data on numerous proteins that can be used to detect and quantify differences in patient and control samples. This in turn can be used as starting point for more focused validation studies on the acquired data and ultimately lead to useful clinical biomarkers. The focus of this study was to utilize and learn mass spectrometric methodologies and to analyze different proteomic processes in sample types. We analyzed the protein-protein interactions in Baker´s yeast PSA1 protein in various points of batch cultivation using database dependent and de novo protein identification methods. We showed that the interactome of PSA1 is very dynamic depending on the phase of the cultivation. We also showed the limitations and benefits of de novo identification and the combined use of both search strategies in improving the confidence of the identifications. In another study using affinity purification and mass spectrometry we identified Fibrillin-2 as the binding partner of lung cancer associated Gremlin-1 protein. This finding elucidates functions and mechanisms of Gremlin-1 and Fibrillin-2 in malignant tissues. In two mass spectrometry-based protein quantification studies we characterized the protein concentration changes in human plasma during liver transplantation surgery as well as the effect of excess sialic acid production in HEK293 model cell line. In the liver transplantation plasma project we identified protein concentration changes in liver in response to the trauma caused by the surgery using label-based iTRAQ method. We showed consumption and secretion of several coagulation related proteins within the liver suggesting activation of coagulation cascade in the very early phases of the craft reperfusion. In the study of excess sialic acid production we first verified the amounts of sialic acid using mass spectrometry-based multiple reaction monitoring method. We were able to induce the production of sialic acid to almost 70-fold compared to control cells. We also monitored the protein abundance changes in sialic acid producing cells using label free proteins quantification method identifying 105 changed proteins. We analyzed those proteins with several functional enrichment tools revealing modifications in cellular protein transport, metabolic and signaling pathways and in remodeling of cellular adherens junctions. Such large scale MS-analyses using ontology-based tools can significantly aid in deciphering the effect of perturbations to complex systems but also reveal novel functional targets for biomarker discovery. The results obtained from targeted interaction experiments as well as large scale quantification studies can be used as basis for more rigorous investigations on the various subjects in search for potential biomarkers for clinical use. The techniques and methods used in the studies also demonstrate the many uses of mass spectrometric techniques in several fields of proteomic and biological research.
  • Leskinen, Markus (Helsingin yliopisto, 2003)
  • Mäyränpää, Mikko (Helsingin yliopisto, 2007)
    More than 40% of all deaths in Finland are caused by atherosclerosis. The complications of atherosclerosis are due to either detachment of the luminal endothelium (erosion) or rupture of the fibrous cap of an atherosclerotic plaque (rupture). As a result, a thrombus is formed at the site of the intimal lesion. Indeed, erosions cause roughly 40% of sudden atherothrombotic deaths and 25% of all atherothrombotic deaths. Erosions are overrepresented in young subjects, diabetics, smokers and women. This dissertation focuses on endothelial erosion. Endothelial erosions were studied in the context of arterial grafting and vascular inflammation. Special attention was given to the role of intimal mast cells and the methodological viewpoints of reliable identification of endothelial erosions. Mast cells are inflammatory cells mostly known for their ability to cause allergic symptoms. In addition to occurring in skin and mucosal surfaces, mast cells are abundant in arterial intima and adventitia. In this study, mast cells were found to associate with endothelial erosions in non-lesional and atherosclerotic human coronary arteries. Thus, mast cells may participate in atherogenesis at the initial phases of the disease process already. We also showed that the mast cell proteases tryptase, chymase, and cathepsin G are all capable of cleaving molecules essential for endothelial cell-to-cell and cell-to-extracellular matrix interactions, such as VE-cadherin and fibronectin. Symptom-causing carotid plaques were found to contain more inflammatory cells, especially mast cells, than non-symptom-causing plaques. Furthermore, the atherogenic serum lipid profile and the degree of carotid stenosis turned out to correlate with the density of carotid plaque mast cells. Apoptotic and proliferating cells were more abundant in non-symptom causing plaques (active renewal of endothelial cells), but erosions were larger in symptom-causing plaques (capacity of endothelial regeneration exceeded). The process of identifying endothelial erosions with immunostainings has been ambiguous, since both endothelial cells and platelets express largely the same antigens. This may have caused inaccurate interpretations of the presence of endothelial erosion. In the last substudy of this thesis we developed a double immunostaining method for simultaneous identification of endothelial cells and platelets. This method enables more reliable identification of endothelial erosions.
  • Hannula, Katariina (Helsingin yliopisto, 2001)
  • Mäkitalo, Laura (Helsingin yliopisto, 2010)
    Matrix metalloproteinases (MMPs) represent a family of 23 metalloendopeptidases, collectively capable of degrading all components of the extracellular matrix. MMPs have been implicated in several inflammatory processes such as arthritis, atherosclerosis, and even carcinomas. They are also involved in several beneficial activities such as epithelial repair. MMPs are inhibited by endogenous tissue inhibitors of matrix metalloproteinases (TIMP). In this study, MMPs were investigated in intestinal mucosa of inflammatory bowel diseases (IBD), chronic intestinal disorders. The main focus was to characterize mucosal inflammation in the intestine, but also cutaneous pyoderma gangrenosum (PG), to assess similarites with IBD inflammation. MMPs and TIMPs were mainly examined in colonic mucosa, in adult Crohn s disease (CD), and paediatric CD, ulcerative colitis (UC), and indeterminate colitis (IC). Ileal pouch mucosa of proctocolectomized paediatric onset IBD patients was also investigated to characterize pouch mucosa. The focus was on finding specific MMPs that could act as markers to differentiate between different IBD disorders, and MMPs that could be implied as markers for tissue injury, potentially serving as targets for MMP-inhibitors. All examinations were performed using immunohistochemistry. The results show that immunosuppressive agents decrease stromal expression of MMP-9 and -26 that could serve as specific targets for MMP-inhibitors in treating CD. In paediatric colonic inflammation, MMP-10 and TIMP-3 present as molecular markers for IBD inflammation, and MMP-7 for CD. MMP expression in the the pouch mucosa could not be classified as strictly IBD- or non-IBD-like. For the first time, this study describes the expression of MMP-3, -7, -9, -12, and TIMP-2 and -3 in pouch mucosa. The MMP profile in PG bears resemblance to both intestinal IBD inflammation and cutaneous inflammation. Based on the results, MMPs and their inhibitors emerge as promising tools in the differential diagnosis of IBD and characterization of the disease subtype, although further research is necessary. Furthermore, the expression of several MMPs in pouch has been described for the first time. While further research is warranted, the findings contribute to a better understanding of events occurring in IBD mucosa, as well as pyoderma gangrenosum.
  • Kuivanen, Tiina (Helsingin yliopisto, 2008)
    The incidence of non-melanoma skin cancer is increasing worldwide. Basal cell carcinoma followed by squamous cell carcinoma and malignant melanoma are the most frequent skin tumors. Immunosuppressed patients have an increased risk of neoplasia, of which non-melanoma skin cancer is the most common. Matrix metalloproteinases (MMPs) are proteolytic enzymes that collectively are capable of degrading virtually all components of the extracellular matrix. MMPs can also process substrates distinct from extracellular matrix proteins and influence cell proliferation, differentiation, angiogenesis, and apoptosis. MMP activity is regulated by their natural inhibitors, tissue inhibitors of metallopro-teinases (TIMPs). In this study, the expression patterns of MMPs, TIMPs, and certain cancer-related molecules were investigated in premalignant and malignant lesions of the human skin. As methods were used immunohistochemisty, in situ hybridization, and reverse transcriptase polymerase chain reaction (RT-PCR) from the cell cultures. Our aim was to evaluate the expression pattern of MMPs in extramammary Paget's disease in order to find markers for more advanced tumors, as well as to shed light on the origin of this rare neoplasm. Novel MMPs -21, -26, and -28 were studied in melanoma cell culture, in primary cutaneous melanomas, and their sentinel nodes. The MMP expression profile in keratoacanthomas and well-differentiated squamous cell carcinomas was analyzed to find markers to differentiate benign keratinocyte hyperproliferation from malignantly transformed cells. Squamous cell carcinomas of immunosuppressed organ transplant recipients were compared to squamous cell carcinomas of matched immunocompetent controls to investigate the factors explaining their more aggressive nature. We found that MMP-7 and -19 proteins are abundant in extramammary Paget's disease and that their presence may predict an underlying adenocarcinoma in these patients. In melanomas, MMP-21 was upregulated in early phases of melanoma progression, but disappeared from the more aggressive tumors with lymph node metastases. The presence of MMP-13 in primary melanomas and lymph node metastases may relate to more aggressive disease. In keratoacanthomas, the expression of MMP-7 and -9 is rare and therefore should raise a suspicion of well-differentiated squamous cell carcinomas. Furthermore, MMP-19 and p16 were observed in benign keratinocyte hyperproliferation of keratoacanthomas, whereas they were generally lost from malignant keratinocytes of SCCs. MMP-26 staining was significantly stronger in squamous cell carcinomas and Bowen s disease samples of organ transplant recipients and it may contribute to the more aggressive nature of squamous cell carcinomas in immunosuppressed patients. In addition, the staining for MMP-9 was significantly stronger in macrophages surrounding the tumors of the immunocompetent group and in neutrophils of those patients on cyclosporin medication. In conclusion, based on our studies, MMP-7 and -19 might serve as biomarkers for more aggressive extramammary Paget's disease and MMP-21 for malignant transformation of melanocytes. MMP -7, -9, and -26, however, could play an important role in the pathobiology of keratinocyte derived malignancies.
  • Hästbacka, Johanna (Helsingin yliopisto, 2013)
    The systemic levels of matrix metalloproteinases (MMPs) -7, -8 and -9 and the tissue inhibitor of metalloproteinases-1 (TIMP-1) were investigated in 877 critically ill patients. In Study I, 15 intensive care unit-(ICU) treated adult patients with secondary peritonitis were prospectively included. Peritoneal fluid, blood and urine samples were collected at the ICU after surgery. The serum and urine levels of MMP-8 were compared with those obtained from ten healthy volunteers, and were found to be significantly higher in patients. In peritoneal fluid, MMP-8 levels were significantly higher than in serum and urine. This study was the first to identify MMP-8 in the peritoneal fluid of peritonitis patients. Study II was a sub-study of the FINNSEPSIS study where patients with severe sepsis or septic shock were prospectively included in 24 Finnish ICUs. Serum samples of 248 patients were analysed for MMP-8, MMP-9 and TIMP-1 levels, that were found to be higher than those of healthy controls. MMP-8, -9 and TIMP-1 levels were compared between ICU survivors and non-survivors. Median MMP-8 (p<0.01) and TIMP-1 (p<0.001) were higher and median MMP-9 levels lower (p=0.047) in ICU non-survivors than in ICU survivors. Study III investigated MMP-7, MMP-8, MMP-9, and TIMP-1 levels on 51 patients resuscitated from cardiac arrest (CA). The patients were a subgroup of the Hypothermia After Cardiac Arrest study. Thirty patients had received mild therapeutic hypothermia treatment (MTH) and 21 non-hypothermia treatment (non-MTH). Serum samples taken at 24 and 48 hours from restoration of spontaneous circulation were analysed and compared between patients and healthy volunteers. Serum MMP and TIMP-1 levels of MTH-treated patients were compared during and after MTH with the levels of non-MTH-treated patients. MMP-8 and MMP-9 were higher in CA patients than controls. Patients receiving MTH treatment had lower median MMP-9 levels during MTH than non-MTH-treated patients (p<0.001). This is one novel potential mechanism of how MTH treatment improves outcome of CA patients. Study IV was a 563-patient sub-study of the FINNALI study that included acute respiratory failure patients at 25 Finnish ICUs. MMP-8 and TIMP-1 were analysed from blood samples taken on study admission and 48 hours thereafter. Association of MMP-8 and TIMP-1 with 90-day mortality was examined. Serum MMP-8 predicted 90-day mortality of acute respiratory failure patients poorly. Admission TIMP-1 levels were higher in non-survivors than in survivors (p<0.001).TIMP-1 was an independent predictor of 90-day mortality, with a moderate discriminative power (AUC 0.633, 95% CI 0.580- 0.686). TIMP-1 was also associated with the severity of oxygenation disturbance. Thus, TIMP-1 is a potentially useful biomarker for predicting outcome in acute respiratory failure patients.
  • Cederqvist, Katariina (Helsingin yliopisto, 2006)
    During inflammation, excess production and release of matrix proteinases, including matrix metalloproteinases (MMPs) and serine proteinases, may result in dysregulated extracellular proteolysis leading to development of tissue damage. Pulmonary inflammation may play an important role in the pathogenesis of lung injury in the preterm infant. The aims of this study were to evaluate involvement of MMPs and serine proteinase trypsin in acute and chronic lung injury in preterm infants and to study the role of these enzymes in acute lung injury by means of an animal model of hyperoxic lung injury. Molecular forms and levels of MMP-2, -8, and -9, and their specific inhibitor, tissue inhibitor of metalloproteinases (TIMP)-2, as well as trypsin were studied in tracheal aspirate fluid (TAF) samples collected from preterm infants with respiratory distress. Expression and distribution of trypsin-2 and proteinase-activated receptor 2 (PAR2) was examined in autopsy lung specimens from fetuses, from preterm infants with respiratory distress syndrome (RDS) or bronchopulmonary dysplasia (BPD), and from newborn infants without lung injury. We detected higher MMP-8 and trypsin-2 and lower TIMP-2 in TAF from preterm infants with more severe acute respiratory distress. Infants subsequently developing BPD had higher levels of MMP-8 and trypsin-2 early postnatally than did those who survived without this chronic lung injury. Immunohistochemically, trypsin-2 was mainly detectable in bronchial epithelium, but also in alveolar epithelium, and its expression was strongest in prolonged RDS. Since trypsin-2 is potent activator of PAR2, a G-protein coupled receptor involved in inflammation, we studied PAR2 expression in the lung. PAR2 co-localized with trypsin-2 in bronchoalveolar epithelium and its expression was significantly higher in bronchoalveolar epithelium in preterm infants with prolonged RDS than in newborn controls. In the experimental study, rats were exposed to >95% oxygen for 24, 48, and 60 hours, or room air. At 48 hours of hyperoxia, MMP-8 and trypsin levels sharply increased in bronchoalveolar lavage fluid, and expression of trypsin appeared in alveolar epithelium, and MMP-8 predominantly in macrophages. In conclusion, high pulmonary MMP-8 and trypsin-2 early postnatally are associated with severity of acute lung injury and subsequent development of BPD in preterm infants. In the injured preterm lung, trypsin-2 co-localizes with PAR2 in bronchoalveolar epithelium, suggesting that PAR2 activated by high levels of trypsin-2 is involved in lung inflammation associated with development of BPD. Marked increase in MMP-8 and trypsin early in the course of experimental hyperoxic lung injury suggests that these enzymes play a role in the pathogenesis of acute lung injury. Further exploration of the roles of trypsin and MMP-8 in lung injury may offer new targets for therapeutic intervention.
  • Wennervirta, Johanna (Helsingin yliopisto, 2010)
    The adequacy of anesthesia has been studied since the introduction of balanced general anesthesia. Commercial monitors based on electroencephalographic (EEG) signal analysis have been available for monitoring the hypnotic component of anesthesia from the beginning of the 1990s. Monitors measuring the depth of anesthesia assess the cortical function of the brain, and have gained acceptance during surgical anesthesia with most of the anesthetic agents used. However, due to frequent artifacts, they are considered unsuitable for monitoring consciousness in intensive care patients. The assessment of analgesia is one of the cornerstones of general anesthesia. Prolonged surgical stress may lead to increased morbidity and delayed postoperative recovery. However, no validated monitoring method is currently available for evaluating analgesia during general anesthesia. Awareness during anesthesia is caused by an inadequate level of hypnosis. This rare but severe complication of general anesthesia may lead to marked emotional stress and possibly posttraumatic stress disorder. In the present series of studies, the incidence of awareness and recall during outpatient anesthesia was evaluated and compared with that of in inpatient anesthesia. A total of 1500 outpatients and 2343 inpatients underwent a structured interview. Clear intraoperative recollections were rare the incidence being 0.07% in outpatients and 0.13% in inpatients. No significant differences emerged between outpatients and inpatients. However, significantly smaller doses of sevoflurane were administered to outpatients with awareness than those without recollections (p<0.05). EEG artifacts in 16 brain-dead organ donors were evaluated during organ harvest surgery in a prospective, open, nonselective study. The source of the frontotemporal biosignals in brain-dead subjects was studied, and the resistance of bispectral index (BIS) and Entropy to the signal artifacts was compared. The hypothesis was that in brain-dead subjects, most of the biosignals recorded from the forehead would consist of artifacts. The original EEG was recorded and State Entropy (SE), Response Entropy (RE), and BIS were calculated and monitored during solid organ harvest. SE differed from zero (inactive EEG) in 28%, RE in 29%, and BIS in 68% of the total recording time (p<0.0001 for all). The median values during the operation were SE 0.0, RE 0.0, and BIS 3.0. In four of the 16 organ donors, EEG was not inactive, and unphysiologically distributed, nonreactive rhythmic theta activity was present in the original EEG signal. After the results from subjects with persistent residual EEG activity were excluded, SE, RE, and BIS differed from zero in 17%, 18%, and 62% of the recorded time, respectively (p<0.0001 for all). Due to various artifacts, the highest readings in all indices were recorded without neuromuscular blockade. The main sources of artifacts were electrocauterization, electromyography (EMG), 50-Hz artifact, handling of the donor, ballistocardiography, and electrocardiography. In a prospective, randomized study of 26 patients, the ability of Surgical Stress Index (SSI) to differentiate patients with two clinically different analgesic levels during shoulder surgery was evaluated. SSI values were lower in patients with an interscalene brachial plexus block than in patients without an additional plexus block. In all patients, anesthesia was maintained with desflurane, the concentration of which was targeted to maintain SE at 50. Increased blood pressure or heart rate (HR), movement, and coughing were considered signs of intraoperative nociception and treated with alfentanil. Photoplethysmographic waveforms were collected from the contralateral arm to the operated side, and SSI was calculated offline. Two minutes after skin incision, SSI was not increased in the brachial plexus block group and was lower (38 ± 13) than in the control group (58 ± 13, p<0.005). Among the controls, one minute prior to alfentanil administration, SSI value was higher than during periods of adequate antinociception, 59 ± 11 vs. 39 ± 12 (p<0.01). The total cumulative need for alfentanil was higher in controls (2.7 ± 1.2 mg) than in the brachial plexus block group (1.6 ± 0.5 mg, p=0.008). Tetanic stimulation to the ulnar region of the hand increased SSI significantly only among patients with a brachial plexus block not covering the site of stimulation. Prognostic value of EEG-derived indices was evaluated and compared with Transcranial Doppler Ultrasonography (TCD), serum neuron-specific enolase (NSE) and S-100B after cardiac arrest. Thirty patients resuscitated from out-of-hospital arrest and treated with induced mild hypothermia for 24 h were included. Original EEG signal was recorded, and burst suppression ratio (BSR), RE, SE, and wavelet subband entropy (WSE) were calculated. Neurological outcome during the six-month period after arrest was assessed with the Glasgow-Pittsburgh Cerebral Performance Categories (CPC). Twenty patients had a CPC of 1-2, one patient had a CPC of 3, and nine patients died (CPC 5). BSR, RE, and SE differed between good (CPC 1-2) and poor (CPC 3-5) outcome groups (p=0.011, p=0.011, p=0.008, respectively) during the first 24 h after arrest. WSE was borderline higher in the good outcome group between 24 and 48 h after arrest (p=0.050). All patients with status epilepticus died, and their WSE values were lower (p=0.022). S-100B was lower in the good outcome group upon arrival at the intensive care unit (p=0.010). After hypothermia treatment, NSE and S-100B values were lower (p=0.002 for both) in the good outcome group. The pulsatile index was also lower in the good outcome group (p=0.004). In conclusion, the incidence of awareness in outpatient anesthesia did not differ from that in inpatient anesthesia. Outpatients are not at increased risk for intraoperative awareness relative to inpatients undergoing general anesthesia. SE, RE, and BIS showed non-zero values that normally indicate cortical neuronal function, but were in these subjects mostly due to artifacts after clinical brain death diagnosis. Entropy was more resistant to artifacts than BIS. During general anesthesia and surgery, SSI values were lower in patients with interscalene brachial plexus block covering the sites of nociceptive stimuli. In detecting nociceptive stimuli, SSI performed better than HR, blood pressure, or RE. BSR, RE, and SE differed between the good and poor neurological outcome groups during the first 24 h after cardiac arrest, and they may be an aid in differentiating patients with good neurological outcomes from those with poor outcomes after out-of-hospital cardiac arrest.
  • Linko, Solveig (Helsingin yliopisto, 2003)
  • Vainiola, Tarja (Helsingin yliopisto, 2014)
    Cost-utility analysis provides a means to determine the health benefit and economic burden of different health-care interventions. In cost-utility analyses, the benefit of care is measured in quality-adjusted life years (QALYs) gained. The calculation of QALYs requires knowledge of the change in health-related quality of life (HRQoL) and assumptions concerning when the benefit of care materialises and how long the benefit lasts. The gold standard for QALY calculations has not yet been defined and, as a consequence, the HRQoL instruments and calculation methods used vary from study to study. The aim of the current study was to clarify how much the differences in the components used for the calculation of QALYs are reflected in the end result, i.e., the number of QALYs gained in the critical care setting. The detailed aims were to study 1) the effect of the instrument used (the EQ-5D or the 15D) on the HRQoL score and the measured changes in it; 2) the effects of the baseline HRQoL and the assumptions concerning the progress of recovery on the number of QALYs; 3) how to estimate life expectancy in the critical care setting, and 4) which factors have an effect on the follow-up HRQoL. The results are based on two study populations. The first population comprises patients having been treated in an intensive care or high-dependency unit (n = 3600), and whose HRQoL was assessed using the EQ-5D and 15D HRQoL instruments 6 and 12 months after treatment. The second population consists of patients having underone treatment in a cardiac surgery intensive care unit (n = 980), and whose HRQoL was assessed using the 15D HRQoL instrument at baseline, when placed on a waiting list for surgery and 6 months after treatment. The results of the studies show that the HRQoL index score is dependent on the instrument used. The distribution of the patients HRQoL scores differed between instruments. The differences are explained, inter alia, by the ceiling effect of the EQ-5D i.e., for a significant proportion of the respondents, the instrument produced the best possible HRQoL score of 1 and by the negative scores of the EQ-5D i.e., for health states worse than death. The 15D produced higher mean HRQoL scores than the EQ-5D. The 15D was able to distinguish between a greater number of health states than the EQ-5D, thus showing a better discriminatory power. The choice of instrument was also reflected in the change observed in HRQoL. The two instruments classified patients according to the change in HRQoL (improved, remained stable, deteriorated) in a similar manner only in approximately half of the cases. The 15D was more sensitive to detecting a change than the EQ-5D. Consequently, both its discriminatory power and responsiveness to change were better than those for the EQ-5D. The assumptions concerning the progression of recovery and the baseline HRQoL score had an effect on the number of QALYs gained both within and between instruments and, consequently, on the cost per QALY ratio. The EQ-5D and the 15D performed differently under different calculation assumptions. The greatest difference in the number of QALYs gained was caused by the negative HRQoL scores observed with the EQ-5D enabling the accrual of more than 1 QALY per year. Patients having been treated in an intensive care unit showed long-lasting excess mortality and, as a consequence, a reduced life expectancy. By contrast, in cardiac surgery patients, the life expectancy was similar to or even better than that of the general population. In patient groups with excess mortality, neither the follow-up time nor the life expectancy of the general population can be regarded as optimal indicators for the duration of the benefit of care. In those patient groups, life expectancy should be extrapolated in relation to the observed excess mortality. In cardiac surgery patients, factors predicting mortality and morbidity are not able to accurately predict the follow-up HRQoL. Instead, patient experiences, such as restlessness and pain during intensive care, predicted poor post-treatment HRQoL. Given that these results are novel, future studies should be directed to patient experiences during treatment. They may be confounding factors in analyses concerning treatment effectiveness, and also diminish the effectiveness of treatment. QALY is not a universal measure, but is dependent on the HRQoL instrument used and on how the factors to be taken into account in the calculation of QALYs are chosen and defined. Furthermore, factors external to the interventions under evaluation, such as the patient s psychological experiences during treatment, may have an effect on the follow-up HRQoL. The ranking of different interventions in terms of their effectiveness calls for standardisation in the calculation of QALYs and more information on the effect of patient experiences during treatment on the follow-up HRQoL  
  • Honkalammi, Johanna (Helsingin yliopisto, 2011)
    Drug-drug interactions may cause serious, even fatal clinical consequences. Therefore, it is important to examine the interaction potential of new chemical entities early in drug development. Mechanism-based inhibition is a pharmacokinetic interaction type, which causes irreversible loss of enzyme activity and can therefore lead to unusually profound and long-lasting consequences. The in vitro in vivo extrapolation (IVIVE) of drug-drug interactions caused by mechanism-based inhibition is challenging. Consequently, many of these interactions have remained unrecognised for many years. The concomitant use of the fibrate-class lipid-lowering agent gemfibrozil increases the concentrations of some drugs and their effects markedly. Even fatal cases of rhabdomyolysis occurred in patients administering gemfibrozil and cerivastatin concomitantly. One of the main mechanisms behind this effect is the mechanism-based inhibition of the cytochrome P450 (CYP) 2C8 enzyme by a glucuronide metabolite of gemfibrozil leading to increased cerivastatin concentrations. Although the clinical use of gemfibrozil has clearly decreased during recent years, gemfibrozil is still needed in some special cases. To enable safe use of gemfibrozil concomitantly with other drugs, information concerning the time and dose relationships of CYP2C8 inhibition by gemfibrozil should be known. This work was carried out as four in vivo clinical drug-drug interaction studies to examine the time and dose relationships of the mechanism-based inhibitory effect of gemfibrozil on CYP2C8. The oral antidiabetic drug repaglinide was used as a probe drug for measuring CYP2C8 activity in healthy volunteers. In this work, mechanism-based inhibition of the CYP2C8 enzyme by gemfibrozil was found to occur rapidly in humans. The inhibitory effect developed to its maximum already when repaglinide was given 1-3 h after gemfibrozil intake. In addition, the inhibition was shown to abate slowly. A full recovery of CYP2C8 activity, as measured by repaglinide metabolism, was achieved 96 h after cessation of gemfibrozil treatment. The dose-dependency of the mechanism-based inhibition of CYP2C8 by gemfibrozil was shown for the first time in this work. CYP2C8 activity was halved by a single 30 mg dose of gemfibrozil or by twice daily administration of less than 30 mg of gemfibrozil. Furthermore, CYP2C8 activity was decreased over 90% by a single dose of 900 mg gemfibrozil or twice daily dosing of approximately 100 mg gemfibrozil. In addition, with the application of physiological models to the data obtained in the dose-dependency studies, the major role of mechanism-based inhibition of CYP2C8 in the interaction between gemfibrozil and repaglinide was confirmed. The results of this work enhance the proper use of gemfibrozil and the safety of patients. The information related to time-dependency of CYP2C8 inhibition by gemfibrozil may also give new insights in order to improve the IVIVE of the drug-drug interactions of new chemical entities. The information obtained by this work may be utilised also in the design of clinical drug-drug interaction studies in the future.
  • Ylikallio, Emil (Helsingin yliopisto, 2011)
    Defects in mitochondrial DNA (mtDNA) maintenance cause a range of human diseases, including autosomal dominant progressive external ophthalmoplegia (adPEO). This study aimed to clarify the molecular background of adPEO. We discovered that deoxynucleoside triphosphate (dNTP) metabolism plays a crucial in mtDNA maintenance and were thus prompted to search for therapeutic strategies based on the modulation of cellular dNTP pools or mtDNA copy number. Human mtDNA is a 16.6 kb circular molecule present in hundreds to thousands of copies per cell. mtDNA is compacted into nucleoprotein clusters called nucleoids. mtDNA maintenance diseases result from defects in nuclear encoded proteins that maintain the mtDNA. These syndromes typically afflict highly differentiated, post-mitotic tissues such as muscle and nerve, but virtually any organ can be affected. adPEO is a disease where mtDNA molecules with large-scale deletions accumulate in patients tissues, particularly in skeletal muscle. Mutations in five nuclear genes, encoding the proteins ANT1, Twinkle, POLG, POLG2 and OPA1, have previously been shown to cause adPEO. Here, we studied a large North American pedigree with adPEO, and identified a novel heterozygous mutation in the gene RRM2B, which encodes the p53R2 subunit of the enzyme ribonucleotide reductase (RNR). RNR is the rate-limiting enzyme in dNTP biosynthesis, and is required both for nuclear and mitochondrial DNA replication. The mutation results in the expression of a truncated form of p53R2, which is likely to compete with the wild-type allele. A change in enzyme function leads to defective mtDNA replication due to altered dNTP pools. Therefore, RRM2B is a novel adPEO disease gene. The importance of adequate dNTP pools and RNR function for mtDNA maintenance has been established in many organisms. In yeast, induction of RNR has previously been shown to increase mtDNA copy number, and to rescue the phenotype caused by mutations in the yeast mtDNA polymerase. To further study the role of RNR in mammalian mtDNA maintenance, we used mice that broadly overexpress the RNR subunits Rrm1, Rrm2 or p53R2. Active RNR is a heterotetramer consisting of two large subunits (Rrm1) and two small subunits (either Rrm2 or p53R2). We also created bitransgenic mice that overexpress Rrm1 together with either Rrm2 or p53R2. In contrast to the previous findings in yeast, bitransgenic RNR overexpression led to mtDNA depletion in mouse skeletal muscle, without mtDNA deletions or point mutations. The mtDNA depletion was associated with imbalanced dNTP pools. Furthermore, the mRNA expression levels of Rrm1 and p53R2 were found to correlate with mtDNA copy number in two independent mouse models, suggesting nuclear-mitochondrial cross talk with regard to mtDNA copy number. We conclude that tight regulation of RNR is needed to prevent harmful alterations in the dNTP pool balance, which can lead to disordered mtDNA maintenance. Increasing the copy number of wild-type mtDNA has been suggested as a strategy for treating PEO and other mitochondrial diseases. Only two proteins are known to cause a robust increase in mtDNA copy number when overexpressed in mice; the mitochondrial transcription factor A (TFAM), and the mitochondrial replicative helicase Twinkle. We studied the mechanisms by which Twinkle and TFAM elevate mtDNA levels, and showed that Twinkle specifically implements mtDNA synthesis. Furthermore, both Twinkle and TFAM were found to increase mtDNA content per nucleoid. Increased mtDNA content in mouse tissues correlated with an age-related accumulation of mtDNA deletions, depletion of mitochondrial transcripts, and progressive respiratory dysfunction. Simultaneous overexpression of Twinkle and TFAM led to a further increase in the mtDNA content of nucleoids, and aggravated the respiratory deficiency. These results suggested that high mtDNA levels have detrimental long-term effects in mice. These data have to be considered when developing and evaluating treatment strategies for elevating mtDNA copy number.
  • Syväranta, Suvi (Helsingin yliopisto, 2013)
    Aortic valve stenosis (AVS) is the most common valvular disease in Western countries. Pharmacological prevention of AVS having proved unsuccessful, its current treatment is still valve replacement. The etiology of AVS is multifactorial, both genetic and external risk factors predisposing to the active pathological process eventually leading to clinically manifest stenosis. Histological features of the disease resemble those of atherosclerosis, including the accumulation and modification of lipoproteins, inflammation, extracellular matrix remodeling, and calcification. Furthermore, valvular interstitial cells undergo phenotypic differentiation into actively proliferating myofibroblasts, which contribute to the local inflammatory response as well as extracellular matrix remodeling in stenotic aortic valves. Blood vessels also grow into the normally avascular valve leaflets already in the early stages of the disease. This thesis aimed at elucidating the mechanisms behind the pathological neovascularization of the stenotic aortic valves. Furthermore, we characterized valvular lymphangiogenesis and investigated potential factors contributing to the balance between valvular angiogenesis and lymphangiogenesis, focusing on the role of valvular myofibroblasts and mast cells. For this purpose, we studied a total of 117 stenotic valves obtained at valve replacement surgery, and 49 control valves obtained at cardiac transplantations, at valve replacement surgery due to aortic valve regurgitation, or from deceased organ donors whose hearts were unsuitable for use as grafts. The valve leaflets were either used freshly for myofibroblast cell culture or frozen for e.g. PCR and immunohistochemical analyses. First, we assessed the adverse extracellular matrix remodeling of stenotic aortic valves, a process necessary for angiogenic sprouting to occur. We found that the mRNA expression levels of cathepsins S, K, and V, and their inhibitor cystatin C were higher in stenotic aortic valves than in control valves. Furthermore, the total activity of such cathepsins was increased in AVS. In immunohistochemical stainings, the expressions of cathepsin S, cathepsin V, and cystatin C localized to valvular macrophages, chondroblast-like cells, and endothelial cells lining both the valvular surface and the neovessels in the stenotic valves. Next, we characterized the neovessels and lymphatic vessels in stenotic aortic valves and control valves using immunohistochemistry. We found that in addition to immature microvessels, the stenotic aortic valves contained organized arterioles, indicating an advanced stage of angiogenesis. Lymphatic vessels correlated with valvular blood vessels, but were present in much fewer numbers. Valvular mast cells resided close to neovessels and secreted the angiogenic Vascular endothelial growth factor A (VEGF-A). Furthermore, we showed that the lymphangiogenic growth factors VEGF-C and VEGF-D are locally produced in the aortic valves, and that the receptors for all these VEGFs, VEGFR-2 and VEGFR-3, are upregulated in AVS. We also identified several factors that induce VEGF-A secretion in cultured valvular myofibroblasts. These include mast cell-derived components, the inflammatory cytokine TNF-α, hypoxia, and cigarette smoke. Myofibroblasts were also able to promote VEGF-A secretion by cultured human mast cells, suggesting potential angiogenic interplay between these two valvular cell types. Interestingly, mast cell-derived proteases also efficiently degraded the lymphangiogenic growth factor VEGF-C. Thus, by secreting VEGF-A, by urging myofibroblasts to produce VEGF-A, and by releasing VEGF-C-degrading proteases, mast cells may strongly influence the observed imbalance between valvular blood vessels and lymphatic vessels. Finally, we investigated the potential effects of oxidized low-density lipoprotein (oxLDL) on valvular angiogenesis. We found that oxLDL induces the expression of several inflammatory cytokines in cultured myofibroblasts. Moreover, we identified oxLDL-binding scavenger receptors to be locally expressed in the aortic valves. The mRNA expression levels of scavenger receptor class A type 1 (SR-A1) and Lectin-like oxidized LDL receptor-1 (LOX-1) were increased in AVS, whereas CD36 was downregulated in stenotic valves. Furthermore, the expression of LOX-1 in cultured valvular myofibroblasts increased in response to mast cell-derived components and TNF-α. The observed changes in valvular scavenger receptor expression particularly favor inflammation and angiogenesis. In conclusion, several angiogenic factors were found to be activated in stenotic aortic valves. Furthermore, valvular mast cells and myofibroblasts were identified as potential players promoting valvular angiogenesis and contributing to the pathological imbalance between valvular angiogenesis and lymphangiogenesis. This imbalance, in turn, could facilitate the harmful infiltration of inflammatory cells and lipoproteins into the stenotic aortic valves and ultimately contribute to the progression of the disease.