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  • Laaksonen , Matti (Helsingin yliopisto, 2010)
    The Enamel matrix derivative Emdogain® (EMD) is a commercially available tissue extract preparation of porcine enamel origin. Studies have shown EMD to be clinically useful in promoting periodontal regeneration. EMD has been widely used in periodontal therapy for over ten years, but the mechanism of its action and the exact composition are not completely clear. EMD is predominantly amelogenin (>90%). However, unlike amelogenin, EMD has a number of growth factor-like effects and it has been shown to enhance the proliferation, migration and other cellular functions of periodontal ligament fibroblasts and osteoblasts. In contrast, the effects of EMD on epithelial cell lines and in particular on oral malignant cells have not been adequately studied. In addition, EMD has effects on the production of cytokines by several oral cell lines and the product is in constant interaction with different oral enzymes. Regardless of the various unknown properties of EMD, it is said to be clinically safe in regenerative procedures, also in medically compromised patients. The aim of the study was to examine whether gingival crevicular fluid (GCF), which contains several different proteolysis enzymes, could degrade EMD and alter its biological functions. In addition, the objective was to study the effects of EMD on carcinogenesis-related factors, in particular MMPs, using in vitro and in vivo models. This study also aimed to contribute to the understanding of the composition of EMD. GCF was capable of degrading EMD, depending on the periodontal status, with markedly more degradation in all states of periodontal disease compared to healthy controls. EMD was observed to stimulate the migration of periodontal ligament fibroblasts (PLF), whereas EMD together with GCF could not stimulate this proliferation. In addition, recombinant amelogenin, the main component of EMD, decreased the migration of PLFs. A comparison of changes induced by EMD and TGF-β1 in the gene profiles of carcinoma cells showed TGF-β1 to regulate a greater number of genes than EMD. However, both of the study reagents enhanced the expression of MMP-10 and MMP-9. Furthermore, EMD was found to induce several factors closely related to carcinogenesis on gene, protein, cell and in vivo levels. EMD enhanced the production of MMP-2, MMP-9 and MMP-10 proteins by cultured carcinoma cells. In addition, EMD stimulated the migration and in vitro wound closure of carcinoma cells. EMD was also capable of promoting metastasis formation in mice. In conclusion, the diseased GCF, containing various proteases, causes degradation of EMD and decreased proliferation of PLFs. Thus, this in vitro study suggests that the regenerative effect of EMD may decrease due to proteases present in periodontal tissues during the inflammation and healing of the tissues in vivo. Furthermore, EMD was observed to enhance several carcinoma-related factors and in particular the production of MMPs by benign and malignant cell lines. These findings suggest that the clinical safety of EMD with regard to dysplastic mucosal lesions should be further investigated.
  • Lallukka, Tea (Helsingin yliopisto, 2008)
    Adverse health behaviors as well as obesity are key risk factors for chronic diseases. Working conditions also contribute to health outcomes. It is possible that the effects of psychosocially strenuous working conditions and other work-related factors on health are, to some extent, explained by adverse behaviors. Previous studies about the associations between several working conditions and behavioral outcomes are, however, inconclusive. Moreover, the results are derived mostly from male populations, one national setting only, and with limited information about working conditions and behavioral risk factors. Thus, with an interest in employee health, this study was set to focus on behavioral risk factors among middle-aged employees. More specifically, the main aim was to shed light on the associations of various working conditions with health behaviors, weight gain, obesity, and symptoms of angina pectoris. In addition to national focus, international comparisons were included to test the associations across countries thereby aiming to produce a more comprehensive picture. Furthermore, a special emphasis was on gaining new evidence in these areas among women. The data derived from the Helsinki Health Study, and from collaborative partners at the Whitehall II Study, University College London, UK, and the Toyama University, Japan. In Helsinki, the postal questionnaires were mailed in 2000-2002 to employees of the City of Helsinki, aged 40 60 years (n=8960). The questionnaire data covered e.g., socio-economic indicators and working conditions such as Karasek s job demands and job control, work fatigue, working overtime, work-home interface, and social support. The outcome measures consisted of smoking, drinking, physical activity, food habits, weight gain, obesity, and symptoms of angina pectoris. The international cohorts included comparable data. Logistic regression analysis was used. The models were adjusted for potential confounders such as age, education, occupational class, and marital status subject to specific aims. The results showed that working conditions were mostly unassociated with health behaviors, albeit some associations were found. Low job strain was associated with healthy food habits and non-smoking among women in Helsinki. Work fatigue, in turn, was related to drinking among men and physical inactivity among women. Work fatigue and working overtime were associated with weight gain in Helsinki among both women and men. Finally, work fatigue, low job control, working overtime, and physically strenuous work were associated with symptoms of angina pectoris among women in Helsinki. Cross-country comparisons confirmed mostly non-existent associations. High job strain was associated with physical inactivity and smoking, and passive work with physical inactivity and less drinking. Working overtime, in turn, related to non-smoking and obesity. All these associations were, however, inconsistent between cohorts and genders. In conclusion, the associations of the studied working conditions with the behavioral risk factors lacked general patters, and were, overall, weak considering the prevalence of psychosocially strenuous work and overtime hours. Thus, based on this study, the health effects of working conditions are likely to be mediated by adverse behaviors only to a minor extent. The associations of work fatigue and working overtime with weight gain and symptoms of angina pectoris are, however, of potential importance to the subsequent health and work ability of employees.
  • Luotola, Kari (Helsingin yliopisto, 2011)
    The upstream proinflammatory interleukin-1 (IL-1) cytokines, together with a naturally occurring IL-1 receptor antagonist (IL-1Ra), play a significant role in several diseases and physiologic conditions. The IL-1 proteins affect glucose homeostasis at multiple levels contributing to vascular injuries and metabolic dysregulations that precede diabetes. An association between IL-1 gene variations and IL-1Ra levels has been suggested, and genetic studies have reported associations with metabolic dysregulation and altered inflammatory responses. The principal aims of this study were to: 1) examine the associations of IL-1 gene variation and IL-1Ra expression in the development and persistence of thyroid antibodies in subacute thyroiditis; 2) investigate the associations of common variants in the IL-1 gene family with plasma glucose and insulin concentrations, glucose homeostasis measures and prevalent diabetes in a representative population sample; 3) investigate genetic and non-genetic determinants of IL-1Ra phenotypes in a cross-sectional setting in three independent study populations; 4) investigate in a prospective setting (a) whether variants of the IL-1 gene family are predictors for clinically incident diabetes in two population-based observational cohort studies; and (b) whether the IL-1Ra levels predict the progression of metabolic syndrome to overt diabetes during the median follow-up of 10.8 and 7.1 years. Results from on patients with subacte thyroiditis showed that the systemic IL-1Ra levels are elevated during a specific proinflammatory response and they correlated with C-reactive protein (CRP) levels. Genetic variation in the IL-1 family seemed to have an association with the appearance of thyroid peroxidase antibodies and persisting local autoimmune responses during the follow-up. Analysis of patients suffering from diabetes and metabolic traits suggested that genetic IL-1 variation and IL-1Ra play a role in glucose homeostasis and in the development of type 2 diabetes. The coding IL-1 beta SNP rs1143634 was associated with traits related to insulin resistance in cross-sectional analyses. Two haplotype variants of the IL-1 beta gene were associated with prevalent diabetes or incident diabetes in a prospective setting and both of these haplotypes were tagged by rs1143634. Three variants of the IL-1Ra gene and one of the IL-1 beta gene were consistently identified as significant, independent determinants of the IL-1Ra phenotype in two or three populations. The proportion of the phenotypic variation explained by the genetic factors was modest however, while obesity and other metabolic traits explained a larger part. Body mass index was the strongest predictor of systemic IL-1Ra concentration overall. Furthermore, the age-adjusted IL-1Ra concentrations were elevated in individuals with metabolic syndrome or diabetes when compared to those free of metabolic dysregulation. In prospective analyses the systemic IL-1Ra levels were found as independent predictors for the development of diabetes in people with metabolic syndrome even after adjustment for multiple other factors, including plasma glucose and CRP levels. The predictive power of IL-1Ra was better than that of CRP. The prospective results also provided some evidence for a role of common IL-1 alpha promoter SNP rs1800587 in the development of type 2 diabetes among men and suggested that the role may be gender specific. Likewise, common variations in the IL-1 beta coding region may have a gender specific association with diabetes development. Further research on the potential benefits of IL-1Ra measurements in identifying individuals at high risk for diabetes, who then could be targeted for specific treatment interventions, is warranted. It has been reported in the recent literature that IL-1Ra secreted from adipose tissue has beneficial effects on glucose homeostasis. Furthermore, treatment with recombinant human IL-1Ra has been shown to have a substantial therapeutic potential. The genetic results from the prospective analyses performed in this study remain inconclusive, but together with the cross-sectional analyses they suggest gender-specific effects of the IL-1 variants on the risk of diabetes. Larger studies with more extensive genotyping and resequencing may help to pinpoint the exact variants responsible and to further elucidate the biological mechanisms for the observed associations. This would improve our understanding of the pathways linking inflammation and obesity with glucose and insulin metabolism.
  • Kauppi, Paula (Helsingin yliopisto, 2001)
  • Karvala, Kirsi (Helsingin yliopisto, 2012)
    Indoor dampness and mold are associated with adverse respiratory health effects, of which asthma is the most frequently diagnosed disease. Respiratory and non-specific symptoms related to building dampness are usually transient, but persistent symptoms appear to be common for some persons, even despite building repairs or a change to an alternative work environment. The study assessed methods for diagnosing occupational asthma induced by indoor dampness and mold. A retrospective analysis of a group of patients examined at the Finnish Institute of Occupational Health in 1995-2004 was conducted. All of the examined 2200 workers had respiratory symptoms related to workplace dampness. According to this study, serial PEF monitoring is an applicable method in the clinical evaluation of occupational asthma induced by indoor dampness. An individual exposure assessment can be based on descriptions of the extent and location of the moisture and mold damage in the building structures and on microbial measurements. Specific IgE-mediated sensitization to molds occurs, but in a small proportion of cases only. Mechanisms of dampness-related asthma remain largely unknown. The patients were followed-up with a questionnaire survey 3-12 years after the baseline examinations. The results suggest that, for workers with work-related asthma-like symptoms occurring in relation to indoor dampness and molds at work, continuing to work in such environments creates a risk for developing asthma. Preventive measures to avoid further exposure seem to be relevant in order to prevent the development of asthma. In practice, such measures would involve the remediation of moisture and mold damage or the relocation of workers to a non-moisture damaged environment. Follow-up at occupational health services is recommended for patients with respiratory symptoms related to workplace dampness. In addition, the long-term effects on the quality of life and work ability of these workers were evaluated. Patients diagnosed with occupational asthma had worse outcomes than did patients with non-occupational asthma or only respiratory symptoms without asthma at the baseline. A perceived poor social climate at work and poor experiences with the supervisor s cooperation at an early stage of symptoms were determinants for impaired self-assessed work ability and early withdrawal from work. In addition, multiple, persistent, indoor-air symptoms at the time of the follow-up increased the risk of poor self-assessed work ability. The results are in accordance with the widely recognized fact that the causes of disability are multifactorial and are not associated with medical conditions only. More apt measures, for example, early support and workplace management practices concerning work ability, are required.
  • Utge, Siddheshwar J. (Helsingin yliopisto, 2012)
    Depression is a complex psychiatric disorder that comprises a variety of symptoms. In addition to depressed mood state, depression has symptoms of disturbed sleep such as early morning awakenings and fatigue. Poor sleep has been demonstrated to be one of the modifiable risk factors in the onset of depression. However, the mechanisms remain largely unknown. In the present study, depressive patients from the Finnish population-based samples were grouped according to the presence or absence of disturbed sleep. The genetic background of depression was hypothesized to be different between the groups. The regulation of sleep, and of mood, was assumed to partly share a common genetic background. The aim of this thesis was to identify genetic variants associated with depression and disturbed sleep in order to gain a better understanding of this hypothesis in the population-based Finnish samples. First, the association between genetic markers from 14 functionally-relevant candidate genes was assessed. These genes were related to serotonergic and glutamatergic neurotransmission, to neural plasticity, and to the hypothalamic-pituitary-adrenal axis (HPA-axis) with depression, depression with early morning awakenings, and depression with fatigue in a sample from the population-based Health 2000 survey. Overall, 1654 individuals were studied (384 depressed patients and 1270 population-matched controls). The data suggested that allelic variants from a gene coding for a key regulatory protein of the serotonergic neurotransmission system, TPH2, is associated with depression accompanied by fatigue in females. An association between a numbers of genes related to glutamatergic neurotransmission and neural plasticity, such as GAD1, GRIA3, and BDNF with depression accompanied by fatigue in females. A significant association between CREB1, a neural plasticity related gene, and depression in men, was also identified. Of the genes related to the HPA-axis, an association was found between CRHR1 and depression accompanied by early morning awakenings in females. The hypothesis was then expanded to encompass 18 genes from the circadian system in the same study subjects (N=1654) from the Health 2000 cohort. In this study, a significant association of two distinctive allelic variants of TIMELESS was associated with depression accompanied by fatigue (Permutation-based corrected empirical P=0.0056), to seasonal mood fluctuation (Pointwise P=0.016) in females, and with depression accompanied by early morning awakenings (Permutation-based corrected empirical P=0.0374) in males. In an independent set of 1512 control individuals (Genmets (D-) sample) from the complete Health 2000 cohort, the same variant was also associated with seasonal mood fluctuation (Pointwise P=0.036) in females, and with early morning awakenings (Pointwise P=0.038) or fatigue (Pointwise P=0.0016) in healthy males. Finally, the shared genetic background for sleep and mood in healthy individuals (N=3147) drawn from the population-based Health 2000 and FINRISK study 2007 survey was examined. In this study, for association analyses with sleep duration, 23 variants from 12 candidate genes were selected that had shown association (P less than 0.05) with depression and disturbed sleep in studies I and II. A significant association of a GRIA3 variation with sleep duration in females (Permutation-based corrected empirical P=0.00001) was identified. The frequency of the allele which associated with depression was highest among females who slept for 8 hours or less in all age groups younger than 70 years. However, no prominent associations were found among males, suggesting a sex-specific effect for the X-chromosomal GRIA3 gene. In conclusion, these results support the involvement of genes related to serotonergic (TPH2) or glutamatergic neurotransmission (GAD1, GRIA3), to neural plasticity (CREB1), to the HPA-axis (CRHR1), and the circadian system (TIMELESS), in the genetic aetiology of depression and disturbed sleep. The results obtained in this thesis support the hypothesis that the different phenotypes of depression and disturbed sleep would also be genetically distinct. Depression is heterogeneous and its genetic background may be partly different in women and men. This study also shows that the regulation of sleep and of mood may have a common genetic background.
  • Lavikainen, Antti (Helsingin yliopisto, 2014)
    The most pathogenic zoonotic cestodes of humans belong to the family Taeniidae. Members of this family (taeniids) are parasites of mammals requiring predatory definitive hosts and herbivorous or omnivorous intermediate hosts. Due to the major medical, veterinary and economic importance, taeniids have been a topic of intensive taxonomic, ecological and epidemiological studies resulting in contrasting conclusions about the diversity within the family. Currently, two genera, Echinococcus and Taenia, are widely recognized. Identification of taeniid tapeworms and their taxonomic classification have traditionally been based on morphological criteria. Development of molecular genetic techniques has provided more accurate tools for identification. The aims of the present thesis were to elucidate evolutionary relationships of taeniids, to explore the diversity within the family and to evaluate the taeniid taxonomy on the basis of phylogenetic relationships. Special emphasis was on species occurring in the Holarctic region. Parasite material collected mainly in northern Europe, a worldwide collection of taeniid DNA specimens and previously published sequence data were used in phylogenetic analyses. Molecular genetic characterization of taeniid taxa and preliminary phylogenies were based on short mitochondrial DNA (mtDNA) sequences. For further phylogenetic analyses, longer mtDNA regions, complete genes and finally mitochondrial genomes, as well as nuclear genes, were used. Based on the molecular analyses, cryptic or previously unknown species and intraspecific entities were detected, and the specific status of some taeniid taxa was confirmed. The genus Taenia was shown to be a highly diversified and paraphyletic assemblage justifying a generic level taxonomic revision. A new genus, Versteria, was created for Taenia mustelae, which was placed as a sister taxon to Echinococcus in phylogenies. An old generic name, Hydatigera, was resurrected for Taenia taeniaeformis and closely related species. The knowledge of taxonomy and evolutionary history of taeniids is essential for better understanding of the epidemiology and transmission of these parasites. The present thesis clarifies the taxonomy of the Taeniidae and creates a framework for further phylogenetic studies, possible additional revisions and comparative research.
  • Tommiska, Johanna (Helsingin yliopisto, 2008)
    Breast cancer is the most commonly occurring cancer among women, and its incidence is increasing worldwide. Positive family history is a well established risk factor for breast cancer, and it is suggested that the proportion of breast cancer that can be attributed to genetic factors may be as high as 30%. However, all the currently known breast cancer susceptibility genes are estimated to account for 20-30% of familial breast cancer, and only 5% of the total breast cancer incidence. It is thus likely that there are still other breast cancer susceptibility genes to be found. Cellular responses to DNA damage are crucial for maintaining genomic integrity and preventing the development of cancer. The genes operating in DNA damage response signaling network are thus good candidates for breast cancer susceptibility genes. The aim of this study was to evaluate the role of three DNA damage response associated genes, ATM, RAD50, and p53, in breast cancer. ATM, a gene causative for ataxia telangiectasia (A-T), has long been a strong candidate for a breast cancer susceptibility gene because of its function as a key DNA damage signal transducer. We analyzed the prevalence of known Finnish A-T related ATM mutations in large series of familial and unselected breast cancer cases from different geographical regions in Finland. Of the seven A-T related mutations, two were observed in the studied familial breast cancer patients. Additionally, a third mutation previously associated with breast cancer susceptibility was also detected. These founder mutations may be responsible for excess familial breast cancer regionally in Northern and Central Finland, but in Southern Finland our results suggest only a minor effect, if any, of any ATM genetic variants on familial breast cancer. We also screened the entire coding region of the ATM gene in 47 familial breast cancer patients from Southern Finland, and evaluated the identified variants in additional cases and controls. All the identified variants were too rare to significantly contribute to breast cancer susceptibility. However, the role of ATM in cancer development and progression was supported by the results of the immunohistochemical studies of ATM expression, as reduced ATM expression in breast carcinomas was found to correlate with tumor differentiation and hormone receptor status. Aberrant ATM expression was also a feature shared by the BRCA1/2 and the difficult-to-treat ER/PR/ERBB2-triple-negative breast carcinomas. From the clinical point of view, identification of phenotypic and genetic similarities between the BRCA1/2 and the triple-negative breast tumors could have an implication in designing novel targeted therapies to which both of these classes of breast cancer might be exceptionally sensitive. Mutations of another plausible breast cancer susceptibility gene, RAD50, were found to be very rare, and RAD50 can only be making a minor contribution to familial breast cancer predisposition in UK and Southern Finland. The Finnish founder mutation RAD50 687delT seems to be a null allele and may carry a small increased risk of breast cancer. RAD50 is not acting as a classical tumor suppressor gene, but it is possible that RAD50 haploinsufficiency is contributing to cancer. In addition to relatively rare breast cancer susceptibility alleles, common polymorphisms may also be associated with increased breast cancer risk. Furthermore, these polymorphisms may have an impact on the progression and outcome of the disease. Our results suggest no effect of the common p53 R72P polymorphism on familial breast cancer risk or breast cancer risk in the population, but R72P seems to be associated with histopathologic features of the tumors and survival of the patients; 72P homozygous genotype was an independent prognostic factor among the unselected breast cancer patients, with a two-fold increased risk of death. These results present important novel findings also with clinical significance, as codon 72 genotype could be a useful additional prognostic marker in breast cancer, especially among the subgroup of patients with wild-type p53 in their tumors.
  • Pakarinen, Sami (Helsingin yliopisto, 2013)
    Dual chamber pacing can be employed to restore atrioventricular synchrony in patients with heart block; and chronotropic incompetence and sinus bradycardia in those with sinus node dysfunction (SND). The focus of this thesis is the feasibility and consequences of proper atrial sensing and pacing to atrioventricular (AV) synchrony in dual chamber pacing. With isolated AV block showed that single lead VDD pacing (single pass ventricular lead with a dual chamber electrode system) can be an alternative to standard dual chamber pacing systems. Adequate sinus-driven atrial rate and no history of paroxysmal atrial fibrillation or cardiac enlargement predict reasonably good long-term maintenance of the VDD pacing mode in elderly patients treated for heart block. Retrograde atrial waves can be discriminated from sinus waves in many patients by using a high sampling rate and algorithms for digital signal processing with data collected by a pacemaker (PM). This approach could enhance the capability of future devices to adapt their stimulation to the spontaneous heart rhythm and improve the collection of diagnostic information on arrhythmias. Atrial tachyarrhythmia (AT) sensing algorithms incorporated in a state-of-the art DDDR (dual lead atrioventricular pacing) pacemaker can accurately identify patients who develop ATs. However transient undersensing of continuous atrial fibrillation (AF) and failure to detect very short episodes ATs can occur frequently, despite the use of refined detection algorithms. With a fixed long AV delay in DDDR pacing as in this study, temporal disruption of AV synchrony and inappropriate mode switch (MS) due to repetitive non-reentrant ventriculo-atrial synchronous rhythm (RNRVAS) is relatively common with SND patients (in 25%) in the presence of retrograde VA conduction. An advanced atrio ventricular search hysteresis (AVSH) algorithm reduced incidence of unnecessary ventricular pacing in the majority of SND patients with both intact and impaired AV conduction and in patients with intermittent AV block, regardless of the lead positions in the right atrium and the ventricle. The avoidance of possible harmful right ventricular (RV) pacing with used state of art AVSH algorithm was not associated with unphysiological over-long AV delays. In conclusion, proper atrial detection and timing for atrioventricular pacing is also feasible in the long-term with contemporary clinical pacing. With appropriate programming, these devices may contribute to the avoidance of possible adverse consequences like congestive heart failure, atrial fibrillation and unwanted harmful symptoms. In future devices with digital signal processing the detection of atrial signals can be further improved.
  • Jurkko, Raija (Helsingin yliopisto, 2009)
    Atrial fibrillation (AF) is the most common tachyarrhythmia and is associated with substantial morbidity, increased mortality and cost. The treatment modalities of AF have increased, but results are still far from optimal. More individualized therapy may be beneficial. Aiming for this calls improved diagnostics. Aim of this study was to find non-invasive parameters obtained during sinus rhythm reflecting electrophysiological patterns related to propensity to AF and particularly to AF occurring without any associated heart disease, lone AF. Overall 240 subjects were enrolled, 136 patients with paroxysmal lone AF and 104 controls (mean age 45 years, 75% males). Signal measurements were performed by non-invasive magnetocardiography (MCG) and by invasive electroanatomic mapping (EAM). High-pass filtering techniques and a new method based on a surface gradient technique were adapted to analyze atrial MCG signal. The EAM was used to elucidate atrial activation in patients and as a reference for MCG. The results showed that MCG mapping is an accurate method to detect atrial electrophysiologic properties. In lone paroxysmal AF, duration of the atrial depolarization complex was marginally prolonged. The difference was more obvious in women and was also related to interatrial conduction patterns. In the focal type of AF (75%), the root mean square (RMS) amplitudes of the atrial signal were normal, but in AF without demonstrable triggers the late atrial RMS amplitudes were reduced. In addition, the atrial characteristics tended to remain similar even when examined several years after the first AF episodes. The intra-atrial recordings confirmed the occurrence of three distinct sites of electrical connection from right to left atrium (LA): the Bachmann bundle (BB), the margin of the fossa ovalis (FO), and the coronary sinus ostial area (CS). The propagation of atrial signal could also be evaluated non-invasively. Three MCG atrial wave types were identified, each of which represented a distinct interatrial activation pattern. In conclusion, in paroxysmal lone AF, active focal triggers are common, atrial depolarization is slightly prolonged, but with a normal amplitude, and the arrhythmia does not necessarily lead to electrical or mechanical dysfunction of the atria. In women the prolongation of atrial depolarization is more obvious. This may be related to gender differences in presentation of AF. A significant minority of patients with lone AF lack frequent focal triggers, and in them, the late atrial signal amplitude is reduced, possibly signifying a wider degenerative process in the LA. In lone AF, natural impulse propagation to LA during sinus rhythm goes through one or more of the principal pathways described. The BB is the most common route, but in one-third, the earliest LA activation occurs outside the BB. Susceptibility to paroxysmal lone AF is associated with propagation of the atrial signal via the margin of the FO or via multiple pathways. When conduction occurs via the BB, it is related with prolonged atrial activation. Thus, altered and alternative conduction pathways may contribute to pathogenesis of lone AF. There is growing evidence of variability in genesis of AF also within lone paroxysmal AF. Present study suggests that this variation may be reflected in cardiac signal pattern. Recognizing the distinct signal profiles may assist in understanding the pathogenesis of AF and identifying subgroups for patient-tailored therapy.
  • Lehto, Mika (Helsingin yliopisto, 2009)
    Atrial fibrillation is the most common arrhythmia requiring treatment. This Thesis investigated atrial fibrillation (AF) with a specific emphasis on atrial remodeling which was analysed from epidemiological, clinical and magnetocardiographic (MCG) perspectives. In the first study we evaluated in real-life clinical practice a population-based cohort of AF patients referred for their first elective cardioversion (CV). 183 consecutive patients were included of whom in 153 (84%) sinus rhythm (SR) was restored. Only 39 (25%) of those maintained SR for one year. Shorter duration of AF and the use of sotalol were the only characteristics associated with better restoration and maintenance of SR. During the one-year follow-up 40% of the patients ended up in permanent AF. Female gender and older age were associated with the acceptance of permanent AF. The LIFE-trial was a prospective, randomised, double-blinded study that evaluated losartan and atenolol in patients with hypertension and left ventricular hypertrophy (LVH). Of the 8,851 patients with SR at baseline and without a history of AF 371 patients developed new-onset AF during the study. Patients with new-onset AF had an increased risk of cardiac events, stroke, and increased rate of hospitalisation for heart failure. Younger age, female gender, lower systolic blood pressure, lesser LVH in ECG and randomisation to losartan therapy were independently associated with lower frequency of new-onset AF. The impact of AF on morbidity and mortality was evaluated in a post-hoc analysis of the OPTIMAAL trial that compared losartan with captopril in patients with acute myocardial infarction (AMI) and evidence of LV dysfunction. Of the 5,477 randomised patients 655 had AF at baseline, and 345 patients developed new AF during the follow-up period, median 3.0 years. Older patients and patients with signs of more serious heart disease had and developed AF more often. Patients with AF at baseline had an increased risk of mortality (hazard ratio (HR) of 1.32) and stroke (HR 1.77). New-onset AF was associated with increased mortality (HR 1.82) and stroke (HR of 2.29). In the fourth study we assessed the reproducibility of our MCG method. This method was used in the fifth study where 26 patients with persistent AF had immediately after the CV longer P-wave duration and higher energy of the last portion of atrial signal (RMS40) in MCG, increased P-wave dispersion in SAECG and decreased pump function of the atria as well as enlarged atrial diameter in echocardiography compared to age- and disease-matched controls. After one month in SR, P-wave duration in MCG still remained longer and left atrial (LA) diameter greater compared to the controls, while the other measurements had returned to the same level as in the control group. In conclusion is not a rare condition in either general population or patients with hypertension or AMI, and it is associated with increased risk of morbidity and mortality. Therefore, atrial remodeling that increases the likelihood of AF and also seems to be relatively stable has to be identified and prevented. MCG was found to be an encouraging new method to study electrical atrial remodeling and reverse remodeling. RAAS-suppressing medications appear to be the most promising method to prevent atrial remodeling and AF.
  • Kieseppä, Tuula (Helsingin yliopisto, 2005)
  • Lamminmäki, Satu (Helsingin yliopisto, 2012)
    Two functioning ears provide clear advantages over monaural listening. During natural binaural listening, robust brain-level interaction occurs between the slightly different inputs from the left and the right ear. Binaural interaction requires convergence of inputs from the two ears somewhere in the auditory system, and it therefore relies on midline crossing of auditory pathways, a fundamental property of the mammalian central nervous system. Binaural interaction plays a significant role in sound localization and other auditory functions, e.g. speech comprehension in a noisy environment. However, the neural mechanisms and significance of binaural interaction and the development of crossed auditory pathways are poorly known. This thesis aimed to expand, by means of magnetoencephalography (MEG), knowledge about binaural cortical processing and midline crossing of auditory pathways in subjects with the defective dyslexia susceptibility gene ROBO1 and in healthy individuals. Study I demonstrated that in dyslexic individuals who carry a weakly expressing haplotype of the ROBO1 gene, binaural interaction is strongly impaired as compared with healthy, age- and sex-matched controls. Moreover, the observed impairment correlated with the expression level of the ROBO1 gene: the weaker the expression, the more abnormal was the binaural interaction. On the basis of previous animal studies and the quite well known anatomy of the subcortical auditory system, we suggest that the normally extensive crossing of auditory pathways is defective in ROBO1-deficient dyslexic subjects. All auditory illusions emerging in healthy individuals rely on normal neurophysiology, and thus illusions elicited by binaural sounds can be valuable in revealing auditory binaural processing. Studies II and III examined the neural basis of peculiar pitch perception and sound localization during the auditory octave illusion originally described by Diana Deutsch in 1974. In the octave illusion, dichotic tones separated by an octave alternate rapidly between the ears so that when the left ear receives the low tone, the right ear receives the high tone and vice versa. Study II demonstrated that transient 100-ms responses (N100m), generated in the auditory cortices, follow the sound location perceived during the illusion. Study III further showed that modifications in normal binaural interactions contribute to the illusory pitch perception. Currently, binaural interaction can be studied non-invasively in detail by means of cortical steady-state responses and MEG-based frequency-tagging. Steady-state responses have also been used in clinical settings to evaluate hearing in non-collaborative patients. Until now, only simple acoustic stimuli have been used to elicit steady-state responses, although in our daily lives we communicate with physically much more complex sounds, such as speech and music. Study IV demonstrated that natural sounds with carefully selected sound parameters can also be used as reliable stimuli in future steady-state studies, and therefore to scrutinize the role and mechanisms of binaural interaction. This thesis links the dyslexia susceptibility gene, ROBO1, to neurodevelopment of auditory system and binaural processing, reveals the sound localization and pitch perception mechanisms during the octave illusion, and provides knowledge about steady-state responses to natural sounds, thereby advancing future binaural interactions studies.
  • Jääskelä-Saari, Hilkka (Helsingin yliopisto, 2009)
    Head and neck squamous cell cancer (HNSCC) is the sixth most common cancer worldwide. Despite advances in combined modality therapy (surgery, radiotherapy, chemotherapy) the 5-year survival rate in stage III and IV disease remains at 40% - 60%. Short-range Auger-electron emitters, such as In-111 and In-114m, tagged with a drug, molecule, peptide, protein or nanoparticles brought in close proximity to nuclear DNA represent a fascinating alternative for treating cancer. In this thesis, we studied the usefulness of Indium-111-bleomycin complex (In-111-BLMC) in the diagnostics and potential therapy of HNSCC using in vitro HNSCC cell lines, in vivo nude mice, and in vivo HNSCC patients. In in vitro experiments with HNSCC cell lines, the sensitivity to external beam radiation, BLM, In-111-BLMC, and In-111-Cl3 was studied using the 96-well plate clonogenic assay. The influence of BLM and In-111-BLMC on the cell cycle was measured with flow cytometry. In in vivo nude mice xenograft studies, the activity ratios of In-111-BLMC were obtained in gamma camera images. The effect of In-111-BLMC in HNSCC xenografts was studied. In in vivo patient studies, we determined the tumor uptake of In-111-BLMC with gamma camera and the radioactivity from tumor samples using In-111-BLMC with specific activity of 75, 175, or 375 MBq/mg BLM. The S values, i.e. absorbed dose in a target organ per cumulated activity in a source organ, were simulated for In-111 and In-114m. In vitro studies showed the variation of sensitivity for external beam radiation, BLM, and In-111-BLMC between HNSCC cell lines. IC50 values for BLM were 1.6-, 1.8-, and 2.1-fold higher than In-111-BLMC (40 MBq/mg BLM) in three HNSCC cell lines. Specific In-111 activity of 40 MBq/mgBLM was more effective in killing cells than specific In-111 activity of 195MBq/mgBLM (p=0.0023). In-111-Cl3 alone had no killing effect. The percentage of cells in the G2/M phase increased after exposure to BLM and especially to In-111-BLMC in the three cell lines studied, indicating a G2/M block. The tumor-seeking behavior was shown in the in vivo imaging study of xenografted mice. BLM and In-111-BLMC were more effective than NaCl in reducing xenografted tumor size in HNSCC. The uptake ratios received from gamma images in the in vivo patient study varied from 1.2 to 2.8 in malignant tumors. However, the uptake of In-111-BLMC was unaffected by increasing the injected activity. A positive correlation existed between In-111-BLMC uptake, Ki-67/MIB activity, and number of mitoses. Regarding the S values, In-114m delivered a 4-fold absorbed radiation dose into the tumor compared with In-111, and thus, In-114m-BLMC might be more effective than In-111-BLMC at the DNA level. Auger-electron emitters, such as In-111 and In-114m, might have potential in the treatment of HNSCC. Further studies are needed to develop a radiopharmaceutical agent with appropriate physical properties of the radionuclide and a suitable carrier to bring it to the targeted tissue.
  • Kekäläinen, Eliisa (Helsingin yliopisto, 2011)
    Autoimmune regulator (AIRE) is the gene mutated in the human polyglandular autoimmune disease called Autoimmune polyendocrinopathy, candidiasis, and ectodermal dystrophy (APECED) that belongs to the Finnish disease heritage. Murine Aire has been shown to be important in the generation of the T cell central tolerance in the thymus by promoting the expression of ectopic tissue-specific antigens in the thymic medulla. Aire is also involved in the thymus tissue organization during organogenesis. In addition to the thymus, AIRE/Aire is expressed in the secondary lymphoid organs. Accordingly, a role for AIRE/Aire in the maintenance of peripheral tolerance has been suggested. Peripheral tolerance involves mechanisms that suppress immune responses in secondary lymphoid organs. Regulatory T cells (Tregs) are an important suppressive T cell population mediating the peripheral tolerance. Tregs are generated in the thymus but also in the peripheral immune system T cells can acquire the Treg-phenotype. The aim of this study was to characterize Tregs in APECED patients and in the APECED mouse model (Aire-deficient mice). In the mouse model, it was possible to separate Aire expression in the thymus and in the secondary lymphoid organs. The relative importance of thymic and peripheral Aire expression in the maintenance of immunological tolerance was studied in an experimental model that was strongly biased towards autoimmunity, i.e. lymphopenia-induced proliferation (LIP) of lymphocytes. This experimental model was also utilised to study the behaviour of T cells with dual-specific T cell receptors (TCR) during the proliferation. The Treg phenotype was studied by flow cytometry and relative gene expression with real-time polymerase chain reaction. TCR repertoires of the Tregs isolated from APECED patients and healthy controls were also compared. The dual-specific TCRs were studied with the TCR repertoire analysis that was followed with sequencing of the chosen TCR genes in order to estimate changes in the dual-specific TCR diversity. The Treg function was tested with an in vitro suppression assay. The APECED patients had normal numbers of Tregs but the phenotype and suppressive functions of the Tregs were impaired. In order to separate Aire functions in the thymus from its yet unknown role in the secondary lymphoid organs, the phenomenon of LIP was utilised. In this setting, the lymphocytes that are adoptively transferred to a lymphopenic recipient proliferate to stimuli from self-originating antigens. This proliferation can result in autoimmunity if peripheral tolerance is not fully functional. When lymphocytes that had matured without Aire in the thymus were transferred to lymphopenic Aire-sufficient recipients, no clinical autoimmunity followed. The Aire-deficient donor-originating lymphocytes hyperproliferated, and other signs of immune dysregulation were also found in the recipients. Overt autoimmunity, however, was prevented by the Aire-deficient donor-originating Tregs that hyperproliferated in the recipients. Aire-deficient lymphopenic mice were used to study whether peripheral loss of Aire had an impact on the maintenance of peripheral tolerance. When normal lymphocytes were transferred to these Aire-deficient lymphopenic recipients, the majority of recipients developed a clinically symptomatic colitis. The colitis was confirmed also by histological analysis of the colon tissue sections. In the Aire-deficient lymphopenic recipients Tregs were proliferating significantly less than in the control group s recipients that had normal Aire expression in their secondary lymphoid organs. This study shows that Aire is not only important in the central tolerance but is also has a significant role in the maintenance of the peripheral tolerance both in mice and men. Aire expressed in the secondary lymphoid organs is involved in the functions of Tregs during an immune response. This peripheral expression appears to be relatively more important in some situations since only those lymphopenic recipients that had lost peripheral expression of Aire developed a symptomatic autoimmune disease. This AIRE-related Treg defect could be clinically important in understanding the pathogenesis of APECED.
  • Joutsi-Korhonen, Lotta (Helsingin yliopisto, 2000)
  • Lehtinen, Miia (Helsingin yliopisto, 2015)
    Background: Worldwide, the leading cause of morbidity and mortality is heart failure. It is most often caused by coronary artery disease (CAD) and myocardial infarction (MI), which causes death of myocardial tissue. Although coronary interventions such as coronary bypass graft surgery (CABG) can restore blood flow to ischemic areas, and established pharmacotherapy for heart failure exists, no treatment available in the clinics can regenerate the dead cardiomyocytes. For surgical treatment, patients with heart failure represent a challenge, as they are prone to surgical complications, and suitable preoperative imaging modalities to assess possible benefit from surgery are few. Aims: Cell therapies have recently emerged as a possible alternative for treating heart failure. We wanted to explore the capacity of autologous bone marrow mononuclear cells to regenerate myocardial tissue as an adjunct to CABG. The aim was to assess the therapy s safety and detect the cells possible effects on cardiac function and viability. In addition, we investigated whether it would be possible to predict benefit from CABG in these heart-failure patients with 3-vessel CAD with the aid of combined nuclear imaging data. For this, we used 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to measure cardiac viability, and 99m-technetium-tetrofosmin single-photon emission computed tomography (99mTc-SPECT) to measure cardiac perfusion. Methods: Between 2006 and 2010, we enrolled 104 patients scheduled for CABG who suffered from CAD and ischemic heart failure. Preoperatively, pharmacotherapy was optimized, after which 39 patients still had left ventricular ejection fraction (LVEF) ≤45%. These patients received injections of bone marrow mononuclear cells (BMMCs) (N=20) or vehicle (N=19) intraoperatively into the myocardial infarction border area in a randomized and double-blind manner. During surgery and at the intensive care unit (ICU), the patients hemodynamics, arterial blood gases, systemic venous oxygen level, blood glucose, acid-base balance, lactate, hemoglobin, body temperature, and diuresis as well as medications needed were monitored and recorded every four hours throughout the first postoperative 24 hours. BMMC effects on the heart were evaluated by use of pre- and 1-year postoperative cardiac magnetic resonance imaging (MRI), FDG-PET, and 99mTc-SPECT and by measuring pro-B-type amino-terminal natriuretic peptide (proBNP) levels. As we later decided to extend the follow-up, these same variables, except for nuclear imaging data, as well as current quality of life were measured at a late follow-up visit in 2013. For this, we could contact 36 of the 39 patients recruited for the original study, of which 30 participated in the extended follow-up. Preoperatively, we also analyzed FDG-PET and 99mTc-SPECT data by using three quantitative techniques with a software tool to measure defects with hypoperfused but viable and non-viable myocardium in 15 control patients. One method used solely PET, two others combined PET and SPECT at different thresholds. As a reference, we used change in LV function and volume by MRI. Results: During the first-year follow-up, improvement was similar in both groups in LVEF, the predefined primary end-point measure (P=0.59), and similar improvement also occurred in local wall thickening (WT) (P=0.68) in the injected segments. Neither changes in viability by PET and SPECT and levels of proBNP differed between these groups. Myocardial scar size by MRI in injected segments rose by a median of 5.1% in the control group (interquartile range, IQR -3.3 to 10.8) but fell by 13.1% in the BMMC group (IQR -21.4 to -6.5) (P=0.0002). During surgery and ICU stay, hemodynamics, arterial blood gases, systemic venous oxygen level, blood glucose, acid-base balance, lactate, hemoglobin, body temperature, and diuresis and levels of medications administered were similar between the study groups. For the extended follow-up, the median period was 60.7 months (IQR 45.1 to 72.6). No statistically significant difference was observable in change in proBNP values or in quality of life between groups. LVEF in both groups remained similarly improved (P=0.647), as also did WT (P=0.434). For controls, scar size in injected segments increased with a median of 2% (IQR -7 to 19); for BMMC patients it remained reduced with a median change of -17% (IQR -30 to -6) (P=0.011). When assessing the benefit-predictive capacity of the two techniques combining FDG-PET and 99mTc-SPECT with different thresholds and one technique using FDG-PET data only, no correlation appeared with preoperative PET- or PET-SPECT-derived viable or non-viable tissue, when compared with global functional outcome (change in LVEF) or local change in WT. Conclusions: In patients with 3-vessel disease and heart failure, the three techniques using SPECT perfusion and PET viability imaging data failed to predict the functional benefit received from CABG. Thus, these imaging modalities may provide no additional advantage to preoperative patient selection, which should be considered when planning treatment for this patient group in the clinics. In the treatment of chronic ischemic heart failure, during surgery and perioperatively in the ICU, both intramyocardial BMMC and placebo injections appear safe. Although failing to affect cardiac function, combining intramyocardial BMMC therapy with CABG can sustainably reduce scar size.