Lääketieteellinen tiedekunta


Recent Submissions

  • Holopainen, Tanja (Unigrafia, 2016)
    Angiopoietins (Angs) and vascular endothelial growth factors (VEGFs) regulate angiogenesis, the formation of new blood vessels, and lymphangiogenesis, the formation of new lymphatic vessels. Angiogenesis is important in cancer, because for continuous growth a primary tumor needs a supply of oxygen and nutrients delivered via blood vessels. In physiological conditions, the lymphatic vasculature serves to collect interstitial fluid as well as to absorb lipid particles. In the context of cancer, lymphatic vessels serve as a route for the metastatic dissemination of tumor cells. This dissertation aimed to explore the role of vascular endothelial growth factor receptor 3 (VEGFR3) and angiopoietin-2 (Ang2) in cancer progression. In particular, the roles of these proteins in the context of tumor angiogenesis and lymphangiogenesis as well as metastasis were investigated in two separate studies. In addition, the effects of the photodynamic ablation of intralymphatic cancer cells and lymphatic vessels on the development of metastases were explored. Furthermore, the effect of the endothelial bone marrow tyrosine kinase in chromosome X (Bmx) on tumor angiogenesis was investigated. We found that the inhibition of VEGFR3 reduces tumor blood vasculature and primary tumor growth. In the second study we found that in-transit tumor cells can be targeted with verteporfin-induced photodynamic therapy. The photodynamic ablation of lymphatic vessels was improved by combining this strategy with anti-lymphangiogenic therapies via the adenovirally mediated soluble expression of the VEGF-C/D trap. Bmx, a member of the Tec non-receptor tyrosine kinase family, was previously shown to promote tumor cell survival, but relatively little is known about the effect of this kinase on tumor biology. Here, we studied the effects of Bmx tumor angiogenesis by using Bmx gene-deleted mice. Some reduction of primary tumor growth in Bmx-/- mice was detected in several isogenic and oncogenic tumor models, along with some attenuation of tumor angiogenesis. Conversely, overexpression of Bmx resulted in increased tumor progression and angiogenesis. Ang2 is known to be a context-dependent agonist of the tyrosine kinase of the Tie2 receptor. Here, we analyzed the effect of Ang2 on metastatic dissemination into the lungs, finding that the overexpression of Ang2 enhanced lung metastasis. In contrast, Ang2 inhibition decreased the occurrence of lung metastases. In the ultrastructural analysis of the metastatic lungs using transmission electron microscopy, anti-Ang2 treatment attenuated tumor-associated changes in metastasis-associated lung capillaries. This dissertation demonstrates that the blockade of VEGFR3 inhibits tumor angiogenesis, and that the inhibition of Ang2 inhibits lymphatic and lung metastasis and improves endothelial integrity. Furthermore, we demonstrated the ability of photodynamic therapy to eradicate lymphatic vessels and intralymphatic cancer cells. These data provide a rationale for developing new cancer therapies targeting the lymphatics in order to reduce metastasis and tumor progression. Taken together, these results provide new insights into endothelial tyrosine kinase-mediated angiogenesis, tumor lymphangiogenesis, and vascular-based therapeutic strategies in cancer.
  • Lahtela, Jenni (Helsingin Yliopisto, 2016)
    Lung cancer is the leading cause of cancer related deaths worldwide. It is characterised with a high level of intra- and intertumour heterogeneity. Large lung cancer sequencing efforts have identified clear histopathology-specific genetic alteration patterns, which in the cases of lung adenocarcinomas are applied in clinics to direct treatment. Furthermore, lung cancer immunotherapy approaches have recently shown promising results in clinical trials. However, a deeper understanding of the functional importance of novel lung cancer genes as well as the lung cancer-related niche and cell type specific propensities leading to molecular and microenvironmental tumour heterogeneity is needed to better translate the growing amount of information to patient stratified treatments. The first part of this thesis work concentrated on the functional in vitro and in vivo investigation of putative tumour suppressive characteristics of the EPH receptor A3 (EPHA3), a gene commonly mutated in human lung cancers. Our in vitro findings supported the tumour suppressive characteristics of EPHA3 and indicated that EPHA3-mediated tumour suppression was specifically dependent on its kinase activity. However, our in vivo investigation demonstrated that loss of EphA3 does not co-operate with two known genetic alterations of human lung cancer in murine lung tumourigenesis nor it effects lung morphogenesis. Hence, we conclude that our study demonstrates how functional validation of putative cancer genes can be challenged by biological complexity, which may result in acquired compensation or different functional roles in human and mice. The results from the second part of this thesis work showed that cells in the airways of mouse lungs had a higher propensity to develop faster growing and progressing lung tumours than the cells in the distal alveolar space when exposed to known lung cancer genetic alterations, namely expression of oncogenic Kras and loss of Lkb1 (KL). The lung tumours originated from the airways were predominantly classified as adenosquamous carcinomas (ASCs). ASCs showed elevated levels of genes associated with immunosuppression and a notable immune cell infiltration with an increase in the amount of possible myeloid-derived suppressor cells (MDSCs). The KL ASC model may thus represent a relevant preclinical model for the study of anti-MDSC immune therapy as a treatment for ASCs, which in humans represent a rare but aggressive type of lung cancer. Thus, the findings in this thesis work highlight the importance of the functional niche in the progression of lung cancer and, therefore, possibly affecting a response to treatment. Niche-specific investigation of lung cancer genetic alterations thus leads to a more accurate stratification of the preclinical in vivo models, simultaneously revealing relevant molecular mechanisms underlying lung cancer heterogeneity.
  • Saukkonen, Suvi (2015)
    Disruptive behavior is one of the most common psychiatric problems in children and adolescents. Psychopathic-like features designate a group of children and adolescents manifesting a severe, aggressive, and persistent pattern of disruptive behavior. These features have many similarities with adult psychopathy. More research is needed to gain an understanding of the different developmental trajectories for psychopathic-like behavior style in children and adolescents. The current study aimed to investigate cognitive, psychosocial, and personality-related characteristics associated with disruptive behavior in children and adolescents. In addition, psychometric properties of one of the psychopathy measures, Antisocial Process Screening Device Self-Report (APSD-SR), were evaluated. In the first study, the working memory (WM) function of school-aged children with Oppositional Defiant Disorder (ODD)/Conduct Disorder (CD) was compared with age- and gender-matched normative controls. The comorbid diagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD) was controlled for in the patient group. WM function was examined using n-back tasks. The main finding of this study was that patients performed worse on WM tasks than controls, even after controlling for the diagnosis of ADHD. The results suggest that children with disruptive behavior disorders (i.e. ODD and CD) have executive function (EF) deficits, like poor WM, that are not accounted for the comorbid diagnosis of ADHD. The second study, using the data from the Finnish Self-Report Delinquency Study 2012 (FSRD-12), assessed the factor structure and internal consistencies of the APSD-SR in a community sample of 15- to 16-year-old youth (n = 4,855, 51% girls). A three-factor structure of APSD-SR was found to fit the data best, with three meaningful subscales representing narcissism, impulsivity, and callous-unemotional features. The internal consistencies for these subscales were adequate. The results suggest that the self-report version of APSD is a promising screening tool for measuring psychopathic-like features in community youth. The third study used the same FSRD-12 data and examined different types of weapon carrying among youth, and psychosocial and personality-related factors associated with carrying a weapon, especially focusing on the relationship between psychopathic-like features and weapon carrying. The results showed that adolescents carrying weapons had a large cluster of problems in their lives, which were differentiated by the type of weapon carried. In addition, psychopathic-like features were associated with an increased likelihood of carrying any type of weapon (knife, gun, other weapon such as knuckleduster, chain, or pepperspray), but the association was strongest with carrying a gun. This association was significant even after controlling for a variety of psychosocial factors. The findings suggest that psychopathic-like features are strongly related to a higher risk of weapon carrying. Furthermore, the findings underscore the need for a comprehensive evaluation of an adolescent s psychosocial situation, when weapon carrying is identified. Finally, the fourth study investigated the relationship between victimization experiences and psychopathic-like features in youth by using the same FSRD-12 data. The results revealed that victimization was related to psychopathic-like features in youth, even more strongly in girls than in boys. Interestingly, the association between victimization and psychopathic-like features was stronger for recent experiences of victimization than past experiences. The results highlight the need for evaluating victimization experiences when psychopathic-like features are present in youth. Furthermore, some of the juveniles may show psychopathic-like behavior style as a means to cope with trauma.
  • Holma, Tanja (Tanja Holma, 2015)
    Outbreaks of bacteria causing hospital and community acquired infections have dramatically increased in number over the recent years. For example, travelers become colonized by resistant bacteria and may transmit the strains to other people and to medical care settings when they return home. The challenge is new and problematic for laboratories performing bacterial diagnostics. Fast and highly specific tools are needed to identify and characterize resistant bacterial strains in order to prevent outbreaks in local hospitals. This thesis studies the fast identification of virulence and resistance genes of the most important hospital acquired (HA) bacteria. In addition, the applicability of rapid outbreak analysis for HA-bacteria using molecular methods outside of the national reference laboratory was studied. The aim of the study was to establish a sensitive, reliable multiplex-PCR method suitable for daily use in a microbiological diagnostic laboratory and to speed up the reporting of bacteria causing outbreaks. Another aim was to study the usefulness and functionality of a commercial repetitive PCR (DiversiLab) and compare it with reference molecular typing methods. The thesis also gives an overall view of the occurrence of HA-bacteria witnessed in the district of Helsinki and Uusimaa over the recent years. The thesis consists of six studies on four different bacterial species/types causing outbreaks: MRSA (methicillin-resistant Staphylococcus aureus), ESBL (Extended Spectrum Beta-Lactamase)-producing Enterobacteriaceae, Acinetobacter baumannii and Clostridium difficile. Consecutive and retrospective bacterial isolates of the each bacteria were collected and examined. The methods used were conventional multiplex PCR and real-time multiplex PCR. The typing methods were repetitive PCR (DiversiLab), PFGE (pulsed field gel electrophoresis), PCR ribotyping, spa typing, and sequencing-based methods. During this thesis three usable in-house multiplex PCRs were established for the detection of MRSA, carbapenemase genes, and virulence genes in C. difficile. The repetitive PCR method, DiversiLab, was found to be a fast and proprietary typing method, very beneficial in the first-line identification of outbreaks. In addition, the Diversilab system may be used in the comparison of resistant bacterial isolates. The method produced better results with Gram-negatives (ESBL-producing Enterobacteriaceae and A. baumannii). However, the reference methods still serve their purpose in global isolate comparison. In the future, whole genome sequencing will, however, most likely replace contemporary typing methods.
  • Maliniemi, Pilvi (Pilvi Maliniemi, 2015)
    This thesis concentrates on exploring novel agents in the pathogenesis of cutaneous T cell lymphomas (CTCL) and reveals potential new biomarkers and therapeutic targets to improve diagnostics. CTCLs are also known as a heterogeneous group of non-Hodgkin lymphomas. The clinical behavior of these lymphomas varies from benign forms of lymphoproliferative diseases such as lymphomatoid papulosis (LyP) to non-progressive mycosis fungoides (MF) and further to rapidly-progressing leukaemic Sézary syndrome (SS). The incidence of the disease is growing, particularly in Western countries. The mechanisms underlying the disease are still largely unknown and thus far no curative therapy exists. Regarding pathogenesis, it has been suggested that persistent antigen stimulation leads to continuous stimulation of T cells and chronic inflammation, eventually causing the development of a malignant T cell clone. Another hypothesis suggests that a specific viral agent could serve as a triggering factor. The first part of this thesis explores the activity of human endogenous retroviruses (HERVs) in CTCLs. HERVs are retroviral sequences comprising about 8% of the human genome and are derived from ancient retrovirus infections of germ line cells. HERVs have their own promoter areas and genes, some of which encode functional proteins. HERVs may also affect the function of neighbouring genes and influence chromosomal instability (e.g. due to random positioning in the genome). However, HERVs are usually epigenetically silenced, but are reactivated in situtations such as cancer. Healthy tissues also show HERV activity. Moreover, tissue-specificity is typical feature of HERVs. We show that a skin-specific HERV pattern is actively transcribed in MF. We also found that the HERV-W-derived viral protein Syncytin-1 is expressed in morphologically malignant lymphocytes. The second part of this thesis is a unique molecular study on a rare subtype of CTCL. Known as subcutaneous panniculitis-like T cell lymphoma (SPTL), this subtype primarily affects young individuals. The diagnosis of SPTL is challenging and SPTL is usually confused with other panniculitis-related inflammatory diseases. The most important finding of the gene expression profiling was the high expression of indoleamine-2,3-dioxygenase (IDO-1), which catabolises the essential amino acid tryptophan (Trp) into kynurenine (Kyn) metabolites. The enzymatic activity of IDO-1 results in the depletion of Trp in the local microenvironment. Because T cells are particularly sensitive to low Trp levels, the process ultimately leads to immunosuppression and subsequent inhibition of T cell responses. Our results suggest that autoimmune inflammation is underlying the development the disease with the support of an immunosuppressive microenvironment. The last part of this thesis is focused on further studying IDO-1 expression in other CTCL subtypes and lymphoproliferative diseases and also how the tumor microenvironment could be involved in malignant transformation. In this study, we showed that distinct subpopulations of CTCL can be recognized based on IDO1-expressing cells. Especially interesting was the finding that IDO-1 is more extensively expressed in LyP rather than in MF, bearing in mind that LyP is a benign disease. Analyzing the Kyn/Trp ratio from patient sera also showed significant differences between MF and LyP. The Kyn/Trp ratio may therefore serve as a potential prognostic biomarker for evaluating disease activity. Taken together, this study revealed completely new information on gene and protein expression in CTCL. The results will likely be most useful in improving future diagnostics as well as patient care. The results may also be further applied in finding new therapeutic targets and developing novel therapies.
  • Lotsari-Salomaa, Johanna (2015)
    Lynch syndrome (LS) is the most common hereditary colon cancer syndrome with germline mutated DNA mismatch repair (MMR) genes predisposing to early onset colon tumors and various extracolonic tumors. Microsatellite instability (MSI) is a hallmark of the Lynch syndrome, but 15% of sporadic tumors show instability of repeated sequences, too. Endometrial carcinoma is the most common LS related extra-colonial tumor. Whether or not breast carcinoma belongs to the Lynch syndrome tumor spectrum has been under debate because of controversial study results. Epigenetic mechanisms regulate gene expression without altering the DNA sequence. DNA methylation is a well-established epigenetic modification. Colon, endometrial and breast carcinomas and endometrial hyperplasia from 256 Finnish Lynch syndrome families were examined for methylation changes as well as several types of genetic alterations. In addition, Finnish sporadic breast tumors with similar hormone receptor statuses to LS breast carcinomas were analyzed. Sporadic colon tumors with microsatellite unstable (MSI) and microsatellite stable (MSS) subgroups from Finnish and Australian populations were also investigated. The first aim was to investigate whether or not breast tumors belong to the Lynch syndrome tumor spectrum by studying the MMR status and the methylation profiles of several tumor suppressor genes. The second aim was to identify epigenetically regulated miRNA genes relevant for colon and endometrial tumorigenesis. The third aim was to examine tumorigenic mechanisms in the minor subset of colon carcinomas with inactive Wnt signaling. The candidate genes identified in the second and third studies were examined for promoter methylation in patient specimens. Breast carcinomas from LS mutation carriers showed significantly higher frequencies of MSI(35%) and loss of MMR protein expression (65%) compared to breast tumors from proven noncarriers (0%) and sporadic cases (0%). This suggested that breast carcinoma is a likely LS spectrum tumor. MMR deficient breast tumors were diagnosed at age 53. RASSF1, APC, CDH13, and GSTP1 genes were often methylated in LS breast tumors, the same as in tumors from several other organs from LS mutation carriers. The CDKN2B gene showed breast cancer specific methylation. A breast tumor may be the first sign of LS, and therefore female MMR mutation carriers should participate in mammographic surveillance. Novel associations between promoter methylation of tumor-suppressive miRNAs or protein coding tumor suppressor genes and clinical subtypes were observed. miR-132 was frequently hypermethylated in sporadic Finnish and Australian MSI tumors compared to paired normal mucosa. miR-132 hypermethylation correlated with traditional (so called CpG island methylator phenotype; CIMP) markers and were associated with the female gender, later onset, and tumors located in the proximal colon. miR-129-2 hypermethylation was seen in advanced endometrial hyperplasia and may be an early marker for endometrial tumorigenesis. The CMTM3, DGKI, and OPCML genes showed frequent hypermethylation in LS and sporadic colon tumors. The EPCAM and KLK10 genes had LS specific methylation. Colon tumors with inactive Wnt signaling were found to constitute a group of tumors with varying features of chromosomal instability and epigenetic dysregulation.
  • Vlachopoulou, Efthymia (2015)
    The Human Leukocyte Antigen (HLA) region is located on chromosome 6 (6p21.3) and its main function is to regulate the immune system. This region has been associated with several autoimmune and other inflammatory conditions. However, many aspects of these associations remain unknown due to high polymorphism, high linkage disequilibrium (LD) and high gene density of this region that increase the complexity and create computational challenges. In this Thesis, the aim is to investigate the HLA haplotype variation in the Finnish population, to evaluate the HLA imputation using two of the existed softwares and to analyze the HLA association with Acute Coronary Syndrome (ACS). The main question in this study is whether the HLA region varies in the Finnish population compared to other populations and how this variation can influence the results of further analyses. The HLA haplotypes showed great variation in the Finnish population compared to other European populations due to different linkage disequilibrium (LD) structures and this highlights the diversity of the HLA haplotypes among different populations. The most common European haplotype HLA-A*01~HLA-B*08~HLA-DRB1*03 shows a lower frequency in Finland, whereas the enrichment of the haplotype HLA-A*03~HLA-B*35~HLA-DRB1*01 was observed (I). Furthermore, the poor imputation results of the HLA-DRB1 gene enhance the power of the previously mentioned arguments (from I) due to the inaccurate imputation from other European populations. The study emphasizes the need for population-specific reference materials for a successful imputation (II). The diversity of HLA alleles, the variability in the frequencies of Single Nucleotide Polymorphisms (SNP) among populations, the difference of the rare HLA alleles appearing in various populations and the extremely high amount of combinations of HLA alleles (due to high polymorphism) contribute to the low success rates of imputation. The association (OR = 4.43, 95% CI = 3.57-5.50) of a novel BTNL2;HLA-DRA;HLA-DRB1*01-haplotype with the risk of Acute Coronary Syndrome (ACS) was identified (III). The analysis showed the implication of the HLA-DRB1*01 allele and the BTNL2 gene to the inflammation process. These two genes affect the antigen presentation and its immune response. Overall, the associated haplotype appeared approximately in 15% of ACS patients and in 5% of healthy individuals. Furthermore, the survival analysis shows that the HLA-DRB1*01 allele does not affect the survival time after an ACS event. Our results provide more insight into the detailed patterns of the haplotypes in the Finnish population, into the success of the imputation approaches and into the HLA association with ACS. Genetic diversity is depicted on these haplotypes which might lead to different immune responses. These findings help future development of appropriate statistical tools for the HLA region.
  • Rautiola, Juhana (2015)
    Renal cell carcinoma (RCC) is the seventh most common cancer in men and the ninth most common in women and it comprises 2-3% of all malignant tumors in adults. In its localized form, the five-year survival is almost 60%. However, in metastatic renal cell carcinoma (mRCC), the five-year survival has historically remained under 10%. Renal cell carcinoma is highly tolerant to traditional chemotherapy and and recent treatment has instead relied on inhibiting the vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) signaling pathways. Since 2005, seven new agents have been approved for the treatment of metastatic RCC. Despite the increased knowledge of RCC, the molecular mechanisms behind acquired and intrinsic resistance to treatment remain largely unknown. Our results demonstrate that hypertension is a strong predictor of good prognosis and response to sunitinib treatment. In addition to hypertension we identified neutropenia and thrombocytopenia as predictive markers of good prognosis. A novel, triple biomarker profile consisting of these adverse events strongly predicts improved survival and outcome in mRCC patients. Results from our investigation of sequential treatment suggest that a newer VEGF receptor inhibitor, pazopanib, has clinically meaningful activity in a patient population where mRCC has progressed through sunitinib treatment and in patients who do not tolerate sunitinib. Encouraged by the fuller understanding of tumor biology, we then investigated the role of an endothelial-cell derived growth factor, angiopoietin-2 (Ang2), on patients outcome. High expression of Ang2 was demonstrated to correlate with a high vessel density and to predict a better response to sunitinib-based first-line therapy.
  • Koskela, Elina (2015)
    Intracranial aneurysms (IAs) affect 2-3% of the population. In Finland, their rupture rate has been exceptionally high. This study aims to evaluate the prevalence and risk factors affecting neuro-ophthalmic findings in patients undergoing treatment for IAs. We also investigate the utility of conventional head computed tomography (CT) in the diagnosis of Terson´s syndrome (TS, vitreous hemorrhage in association with aneurysmal subarachnoid hemorrhage (aSAH)). Patients treated endovascularly or microsurgically for their IAs at the Department of Neurosurgery, Helsinki University Central Hospital, in 2011 prospectively underwent a neuro-ophthalmic examination preoperatively and at 3 days, 14 days, 2 to 4 months, and 6 months postoperatively. Findings suggestive of TS, as independently reviewed by two radiologists, on conventional CT head scans were compared with dilated fundoscopic findings. Participants comprised 121 patients with a ruptured aneurysm and 142 patients with an unruptured intracranial aneurysm (UIA). TS was present on fundoscopy in 13 patients (11%); the overall observed agreement between the two radiologists was 96% (116/121), with a substantial κ of 0.69 (95% CI 0.56-0.82). On average, CT demonstrated sensitivity of 42% and specificity of 97%. Factors independently predicting TS were female gender (OR 5.34, 95% CI 1.05-27.17) and World Federation of Neurosurgical Societies (WFNS) grade (OR 15.05 for grades IV-V vs. I-III, 95% CI 3.07-73.89). For patients with aSAH, the frequencies of a third, fourth, or sixth nerve palsy were 11 (9%; preoperatively), 16 (13%; immediately postoperatively), and 3 (3%; at the last follow-up), compared with corresponding frequencies of 6 (4%), 15 (11%), and 7 (5%) for patients with UIAs. Significant risk factors for postoperative eye movement disorders (EMDs) among patients with UIAs were aneurysm location in the posterior circulation (OR 142.02, 95% CI 20.13-1002.22) and aneurysm size (OR 1.28, for each 1-mm increase in diameter, 95% CI 1.12-1.47). After a follow-up time of 6 months, patients with aSAH presenting with visual field defects (VFDs) for aneurysm- or operation-related reasons numbered 20 (19%); homonymous VFDs were the most prevalent finding, and in logistic regression analysis, they were significantly associated with the Hunt and Hess (H and H) grade (OR 4.45 for grades IV-V vs. I-III, 95% CI 1.21-16.39) and presence of intracranial hemorrhage (OR 8.93, 95% CI 2.14-37.28). By contrast, seven patients (5%) treated for a UIA had VFDs. Poor-grade aSAH (H and H or WFNS grade IV-V) appears to be a strong predictive factor for TS and VFDs. With a high specificity value, conventional head CT scan might prove a useful tool in the diagnosis of TS. Although a common finding in the acute postoperative stage of ruptured and unruptured IAs, EMDs show marked improvement during follow-up.
  • Lindh, Erika (Hansaprint, 2015)
    Influenza A virus (IAV) is a significant zoonotic pathogen, with a diverse range of subtypes infecting both humans and birds. NDV is the causative agent of Newcastle Disease, a significant infectious disease of poultry. While wild waterfowl, the natural host, remains apparently healthy during the even frequent infections with these viruses, poultry is susceptible for mild to severe disease. Both viruses have a heavy impact on the poultry industry by causing outbreaks with significant economical losses. Low pathogenic IAV and NDV viruses are efficiently transmitted in host populations and have the ability to mutate and become virulent. The segmented genome of IAV also allows it to reassort during dual infections, giving rise to novel viruses with unpredictable pathogenic properties including the potential to transmit to humans and other mammals. Extensive surveillance studies of IAV and NDV during the past decades have revealed their wide global distribution and host species range. Previous surveillance studies have yielded limited information about avian IAV in Finland and so far, NDV has been the causative agent of varying outbreaks in Finland, for example in poultry, a zoo and domestic pigeons. This project was initiated for surveillance purposes, to gather information about prevalence and subtype/genotype distribution of IAVs and NDVs and to assess the potential presence of highly pathogenic strains in wild waterfowl in Finland. Through annual sampling and screening of wild waterfowl, 875 birds were screened during the years 2006-2010 and 2014. The birds represent mainly young, hunted ducks from local breeding areas. We detected altogether 76 IAVs (in 8.7%) and 39 NDVs (in 5.5%). From most of the samples (75%) the viruses were successfully propagated in embryonated chicken eggs and partially sequenced for phylogenetic and pathogenicity analyses. Importantly, while no highly pathogenic strains were encountered, several of the wild waterfowl derived viruses detected in Finland were phylogenetically closely related to viruses detected during outbreaks in Finland and elsewhere in Europe. These viruses includ IAV subtypes H5N2, H7N3, H9N2 as well as NDVs. An unexpectedly high subtype dominance of H3N8 was recorded each year, counting for over 60% of all the subtyped IAVs. Genetic characterization of these viruses demonstrated high sequence homology, even between temporally separated viruses and suggests local perpetuation of the viruses. The past decades have witnessed an increase in the incidence of IAV outbreaks in poultry in Europe and zoonotic transmission of a growing number of subtypes. Surveillance data of IAV in the natural host is important for designing efficient national policies aiming to control the transmission of IAV to susceptible populations and for risk assessment. Our results also show that the northern breeding sites have implications on a European scale.
  • Nevalainen, Maarit (Unigrafia, 2014)
    The aim of this study was to investigate medical students and primary care physicians feelings of uncertainty, experiences of medical errors and ways of coping with them, and attitudes towards the career of a GP. In Study I the learning diaries (n=79) and writings on specific themes (n=94) of 22 students during their first clinical year were analysed by thematic content analysis. The topics uncertainty and medical errors were studied in more detail. Studies II and III are based on the responses of 5th-year students to a cross-sectional survey (Study II, n=307 and Study III, n=309, response rate 86%) during their main course in general practice. Study IV concerned younger (n=85) and experienced physicians (n=80) responses to an electronic survey related to uncertainty and experiences of medical errors (response rate 68%). Factors predisposing physicians to medical errors and means to avoid making them were assessed. In the second, third and fourth studies the responses were cross-tabulated. The variables are presented as means with standard deviations and percentages. Comparisons of categorial variables were carried out by using the X2 test or Fischer s exact test, comparisons of non-normally distributed continuous variables were made by using the Mann-Whitney U-test. (P values less than 0.05 were considered significant.) 95% CIs are presented for the most important results. Logistic regression analysis was used to explore which factors predicted good tolerance of uncertainty among GPs. A developmental path among the 3rd- to 4th-year medical students was discovered regarding their experiences of uncertainty and fears medical errors. All students wrote about several aspects of uncertainty. They also feared mistakes. However, they started gradually to be more confident in coping with responsibility. The 5th-year medical students were divided into two groups based on their tolerance of uncertainty and fear of medical errors. Those who tolerated uncertainty quite well or well (n=240, 78%) were older, more often males, and had been working for a longer time as locum doctors than those tolerating uncertainty poorly (n=67, 22%). In the latter group, 100% were afraid of medical errors, in the former group the figure was 86%. Those tolerating uncertainty poorly felt more often that a GP s work is too challenging and difficult and involves too much responsibility. About 3/4 of the fifth-year medical students considered the work of a GP positively versatile and challenging, but about 2/3 of them considered it to be too hasty and pressing. The females thought that a GP s work is too lonely. The males considered that a GP deals too much with non-medical problems and the work may be too routine and tedious. According to the majority of the students (82%) the most important aim of a GP s work is to identify serious diseases and refer such patients to specialized care. In the fourth study 6% of the younger and 1% of the experienced physicians tolerated uncertainty poorly. The younger physicians feared medical errors more (70% vs. 48%) and more often admitted having made an error (84% vs. 69%) compared to the experienced ones (48%). The experienced physicians apologized more willingly to their patients for an error. The younger physicians were more prone to use electronic databases and consult on site. Tolerance of uncertainty seems to develop gradually during the medical studies and this development also continues after graduation. Students are already aware of the possibility of a medical error. Almost all of them are afraid of them. Also half of the experienced physicians admitted to feeling some fear. The attitudes of fifth-year medical students reflect their experiences of general practice.
  • Niinistö, Sari (Unigrafia, 2014)
    The aim of the present study was to evaluate the associations between the maternal intakes of fatty acids, vitamin D, and their respective dietary sources during pregnancy or lactation, as well as the child s fatty acid status, and the risk of type 1 diabetes. The present study is a prospective cohort belonging to the nutrition part of the Finnish Type 1 Diabetes Prediction and Prevention Study (DIPP). The cohort comprised children at increased genetic risk for type 1 diabetes (n=6069) born at the Oulu and Tampere University Hospitals between the years 1997 and 2004. Maternal diet was assessed with a validated food frequency questionnaire during the 8th month of pregnancy and the 3rd month of lactation. The children were monitored for the appearance of autoantibodies associated with type 1 diabetes and for the development of clinical type 1 diabetes, at intervals between 3 and 12 months. The associations between the maternal intakes of fatty acids, vitamin D, as well as their respective food sources and the endpoints, were analyzed by the piecewise linear log-hazard survival model and Cox proportional hazard analyses. The associations between the children s serum fatty acid composition and the risk of type 1 diabetes were studied in a nested case-control study design that included 108 children with preclinical type 1 diabetes and 216 matched controls. The total serum fatty acid composition was analyzed by gas chromatography from samples that were taken from the children between the ages of 1 and 6 years. Conditional logistic regression was applied in the statistical analysis. After adjustment for putative confounders, neither the maternal intake of fatty acids during pregnancy and lactation nor the intake of vitamin D during pregnancy, showed any association with the development of type 1 diabetes. The maternal use of fresh milk and cheese, and the intake of protein from fresh milk during pregnancy, were associated with a lower risk of clinical type 1 diabetes. The maternal total consumption of red meat and meat products, particularly processed meat, during lactation was associated with an increased risk of type 1 diabetes. The child s serum profile of milk-associated fatty acids at, or closest to, the time of seroconversion, was associated with a higher risk of preclinical type 1 diabetes. Findings give one of the first indications that prenatal exposure to certain dairy foods may affect immune regulation, and our results on the milk-associated fatty acid biomarkers confirm the previous findings that the child s own direct cow s milk exposure is associated with autoimmunity in children with increased genetic risk of type 1 diabetes. These results thus indicate that milk and meat products in particular, are interesting topics for future studies on potential nutritional risk and protective factors for type 1 diabetes.
  • Malmivaara, Kirsi (Helsingin yliopisto, 2014)
    The overall purpose of this study was to evaluate the health-related quality of life (HRQoL) and cost-effectiveness of the treatment of severely, acutely ill neurosurgical patients. The majority of the study illnesses and conditions are known to have a relatively high mortality or an otherwise poor outcome but, they are also known to be highly resource-demanding. Since the economics of health care is attracting more and more interest, it will become more important to evaluate the cost-effectiveness of treatment so that it can be demonstrated that the resource allocation is justified. The patients (n=620) for these four separate studies were treated in the Department of Neurosurgery of Helsinki University Central Hospital between 1998 and 2006. The first of these four studies was a Step-Down Unit study in which we evaluated a group of patients (n=346) who underwent a major neurosurgical operation and were treated in the neurosurgical intensive care unit (NICU) and, due to a poor prognosis, were then discharged from the NICU to the step-down unit, still depending on life support devices. The following two studies evaluated patients who underwent a decompressive craniectomy (DC) for intractable intracranial pressure. The first of these, the DC after SAH study, concerned patients (n=42) with subarachnoid haemorrhage (SAH) or other neurological emergencies, and the second one, the DC after TBI study, evaluated patients (n=54) with traumatic brain injury (TBI). The fourth study, the SAH study (n=178), evaluated the long-term outcome, HRQoL and cost-effectiveness of the treatment of the SAH patients. The mortality in the Step-Down Unit study and both of the DC studies was high and moderate in the SAH study, 59%, 53%, 41%, and 24% respectively. The median follow-up times were 5, 3, 5.6 and 10.8 years. The health-related quality of life was assessed with the EuroQol EQ5D instrument and the median HRQoL index was compared to the median index of the Finnish reference population (0.85). The indices were 0.71, 0.41, 0.85 and 1.00. The outcome was also evaluated on the Glasgow outcome scale (GOS), and 49%, 25%, 69% and 75% of the patients achieved a good outcome (GOS 1-2). An important measure of well-being is the ability to live at home, and 49%, 50%, 78% and 88% of the study patients were able to live at home. The direct costs of the neurosurgical treatment per quality adjusted life year (QALY) were 2521 , 5000 , 2400 and 1700 . For the total of 620 severely ill neurosurgical patients treated in the Helsinki Department of Neurosurgery between 1998 and 2006, we found the treatment to be cost-effective, and it resulted in health-related quality of life that varied from acceptable to good when compared to the reference population. We found no evidence of unnecessary prolongation of human suffering when death was inevitable. The worst state of health-related quality of life did not occur among the survivors. In summary, these studies indicate that current healthcare resources are utilized cost-effectively to achieve a life that is meaningful. Allocation of healthcare resources to the severely ill neurosurgical patients seems to be justified.
  • Zheng, Wei (2013)
    Blood vessels deliver nutrients and oxygen to tissues, whereas lymphatic vessels collect interstitial fluid and absorb lipids. Both types of vessels are involved in immune surveillance. Malformation or malfunction of either vasculature is closely associated with various diseases. Although the molecular mechanisms regulating the growth, development and function of these vessels have begun to emerge in recent decades, many questions remain. This study aimed to understand if and how the growth of new blood and lymphatic vessels (angiogenesis and lymphangiogenesis, respectively) is regulated by the endothelial signaling molecules BMX, VEGFR-3, notch 1 and angiopoietin-2. BMX, a non-receptor tyrosine kinase, is upregulated in some types of cancer and promotes cell survival, migration and proliferation. Under physiological conditions, it is also highly expressed in blood endothelial cells (BECs). Thus, we hypothesized that BMX might contribute to tumor growth by promoting tumor angiogenesis. Using multiple tumor implantation and spontaneous tumor models in Bmx gene-deleted mice, we found that tumor angiogenesis and growth were significantly reduced in the absence of BMX. Conversely, when BMX was overexpressed in epithelial keratinocytes, chemical carcinogen led to increased tumor angiogenesis and growth. VEGFR-3 is a growth factor receptor on the surface of endothelial cells (ECs). Here, we characterized a blocking antibody that inhibits VEGFR-3 signaling by a novel mechanism. In contrast to conventional blocking antibodies that prevent ligand-receptor binding, this new antibody inhibited dimerization of two identical VEGFR-3 molecules, thereby impairing signaling activation and sprouting of lymphatic endothelial cells (LECs). These inhibitory effects persisted even at ligand concentrations so high that conventional blocking antibodies were no longer effective. Importantly, concurrent treatment with both types of antibodies yielded combined additive benefits. Notch signaling regulates angiogenic sprouting. We found in this study that Notch inhibitors enhance VEGF-induced lymphatic sprouting in 3-dimensional EC sprouting assays in vitro. In vivo, VEGF alone induced only lymphatic dilation but not sprouting. However, concomitant treatment with a Notch inhibitor induced both vascular events. In addition, a mosaic-sprouting assay showed that Notch signaling also determined the fates of tip/stalk cells (the cell leading a vessel sprout and the following cells, respectively) during lymphatic sprouting. Angiopoietin-2 (Ang2) is an endothelial growth factor required for proper lymphatic remodeling during development, but the exact mechanisms of this process have previously remained unclear. In contrast to the zipper-like pattern of cell-cell junctions (zippers) in collecting lymphatic vessels, mature lymphatic capillaries have a distinct pattern of button-like junctions (buttons), which transform from zippers during development. We found in this study that Ang2 is indispensable for such transformation of the junctional patterns during embryogenesis. At the molecular level, Ang2 is required for phosphorylation of the adherens junction marker vascular endothelial cadherin (VE-cadherin) at the tyrosine residue 685. Ang2 blocking antibody treatment of mouse neonates disrupted cell-cell junctions in the mesenteric lymphatic vessels, causing leakage of chyle (milky fluids containing fat droplets and lymph). Ang2 blockade also inhibited lymphatic valve formation and maturation and resulted in abnormal smooth muscle recruitment. Together, these results provide new insights into the molecular mechanisms of angiogenesis and lymphangiogenesis. Elucidation of these mechanisms is important in developing new drugs for the treatment of vessel-related diseases, including cancer and pathological inflammation. Moreover, these findings introduce the reorganization of cell-cell junctions as a novel parameter for evaluating lymphatic development and call for future research into this new field.
  • Matilainen, Olli (2013)
    The ubiquitin-proteasome system (UPS) is the major pathway for controlled protein degradation in the cell. Substrates destined for degradation are polyubiquitinated by ubiquitin ligating enzymes and degraded by the proteasome, which is a complex multisubunit enzyme of over 2.5 MDa. Due to its essential role in maintenance of the cellular protein homeostasis, dysfunctions in proteasome activity have been linked to many severe disorders, such as Alzheimer s, Parkinson s and Huntington s disease and some cancers. Although the proteasome takes part in almost all cellular processes, it is still unclear which factors contribute to regulation of proteasome function. The aim of this thesis was to elucidate mechanisms of how proteasome activity is regulated in a multicellular organism. To enable monitoring and quantification of proteasome activity in vivo, a photoconvertible reporter system was developed to live image proteasome activity in C. elegans. By using this system, it was uncovered that proteasome activity varies between different tissues, as GABAergic and dopaminergic neurons showed faster reporter degradation than muscle cells, and that aging affects proteasome activity in a tissue-dependent manner. Subsequently, it was investigated whether signaling pathways regulating aging also affect proteasome activity. Insulin/IGF-1 signaling (IIS) is an evolutionarily conserved signaling pathway regulating lifespan in worms, flies, rodents and possibly humans. By using C. elegans as a model organism, this thesis shows that IIS regulates proteasome activity through the FOXO/DAF-16 and Nrf/SKN-1 transcription factors. Moreover, it was demonstrated that DAF-16, which is activated by reduced IIS, inhibits the expression of the proteasome-associated deubiquitinating enzyme UBH-4, which was shown to function as a tissue-specific proteasome inhibitor. The role of UBH-4 appears to be well-conserved, as downregulation of its mammalian ortholog, UCHL-5, increases proteasome activity and degradation of proteotoxic proteins in mammalian cells. Taken together, this thesis provides tools to study proteasome activity in vivo, and establishes a molecular mechanism linking IIS to efficiency of proteasomal degradation. These results can be utilized when designing new therapies for proteasome-associated diseases, especially for disorders that may be alleviated with tissue-specific modulation of proteasome activity.