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  • Grönholm, Mikaela (Helsingin yliopisto, 2005)
  • Ola, Roxana (Helsingin yliopisto, 2012)
    Glial-cell-line-derived neurotrophic factor (GDNF) signaling through the receptor tyrosine kinase Ret and its co-receptor Gfrα1 is indispensable for the ureteric bud (UB) outgrowth from Wolffian ducts during kidney differentiation. To search for novel genes regulated by GDNF in Wolffian ducts and early UB epithelium, we performed a genome wide analysis of Wolffian ducts exposed by GDNF in vitro, and identified 69 up-regulated genes. Plakophilin2 gene encoding for the armadillo protein- Pkp2 and Visinin like 1 gene, encoding for a neuronal calcium sensor protein- VSNL1 were among the highly up-regulated genes and their expression was missing in the Gdnf- null kidneys. Analysis of the Pkp2- null allele kidneys revealed a defect in ureteric branching. The Pkp2-/- kidney explants did not undergo UB formation and branching in vitro, but responded to GDNF by producing supernumerary buds, suggesting that Pkp2 is not essential for UB formation from the Wolffian duct. VSNL1 characterized the tip domain of the UB epithelium regardless of the inducer. In the UB tips, VSNL1 displayed a unique mosaic expression pattern that demonstrated the heterogeneity of cells in the tip. VSNL1 expression was mutually exclusive with β-catenin activity as shown in Bat-gal Wnt-reporter mice. VSNL1 was downregulated in both β-catenin stabilized and β-catenin deficient kidneys. Moreover, VSNL1 transduction compromised β-catenin stability in cultured cells. The results suggest an antagonistic effect between VSNL1 and β-catenin. The spatial and temporal expression of VSNL1 and its mRNA was further addressed during mouse embryogenesis. Vsnl1 was specifically confined to the cardiac anlagen. All myocardial cells that contributed to the remodeling of the venous pole of the heart were positive for Vsnl1. An expansion of the VSNL1 expression domain to the ventricles was seen soon after the first week of postnatal life, and this pattern was maintained to adulthood. The function of PlexinB2 during renal development was finally addressed by analyzing the kidney phenotype in Plxnb2- null mice. These embryos displayed hypoplastic kidneys, and occasional unilateral double kidneys and ureters. The defect in branching was intrinsic to the ureteric epithelium. By co-immunoprecipitation experiments, PlexinB2 was shown to interact with Ret suggesting that PlexinB2, activated by Sema4C ligand, may modulate ureteric branching by a direct regulation of Ret activity.
  • Sillanpää, Heidi (Helsingin yliopisto, 2014)
    Lyme borreliosis (LB) is a bacterial infection spread by the bite of Ixodes sp. ticks. Borrelia burgdorferi sensu lato group of spirochaetes is causing the infection. Less than 10 species are known to be pathogenic to humans. Distribution of B. burgdorferi sensu lato species varies geographically and LB is endemic in Europe, Asia and North America. The typical initial manifestation of LB is a ring-like rash, erythema migrans (EM). EM appears around the tick bite site after a couple of days or weeks. Diagnosis of LB is based on EM and the infection is treated with antibiotics. In some cases, the tick bite or EM may go unnoticed. Manifestations of late-stage LB are Lyme arthritis, cardiac symptoms, neuroborreliosis (LNB) manifesting as meningoradiculitis or meningitis, or chronic atrophic skin changes (acrodermatitis chronica atrophicans). These late-stage manifestations may appear within weeks, months, or in rare occasions after years. Frequently, laboratory tests are needed to confirm the clinical diagnosis. Laboratory testing is mainly based on the detection of Borrelia specific antibodies, usually with ELISA method or immunoblotting. There are no markers of active LB and antibody responses may persist for years after the treatment of the infection. The aim of this study was to identify new immunological markers for the laboratory diagnostics of LB. A large amount of serum and cerebrospinal fluid (CSF) samples were collected from patients with different manifestations of LB from Europe and the United States. Five peptide variants of IR6 (= invariable region 6 of the VlsE protein) as antigens were compared to commercial C6 Immunoassay in the serodiagnosis of early and disseminated stages of LNB. Recombinant decorin binding proteins A (DbpA) and B (DbpB) (three variants of each) as antigens were evaluated in the serodiagnosis of LNB. CXCL13 Immunoassay was used to measure chemokine CXCL13 levels in children with early LNB. As a conclusion, the use of a combination of different IR6 peptide variants in one assay may improve the laboratory diagnostics of LB by increasing the sensitivity of the test. DbpA and DbpB may serve as supplementary antigens in diagnostic assays. Appearance of CXCL13 in the CSF seems to be an early immunological marker of inflammation in CNS. Measurement of CXCL13 concentrations in the CSF may improve the diagnostics of LNB.
  • Moza, Monica (Helsingfors universitet, 2008)
    In skeletal and cardiac muscle cells, the contractile unit sarcomere consists of actin filaments that have constant length, a strict spatial distribution and are aligned with myosin filaments. Actin filaments from adjacent sarcomeres are cross-linked by actin-associated proteins which form the Z-disk. Sarcomeres provide the muscle cell its shape and they are the structural and functional basis of the muscle contraction. In response to intra- and extracellular stimuli, the actin cytoskeleton is continuously reorganizing in non-muscle or smooth muscle cells in order to determine the cell morphology, the cytokinesis, coordinated cell movements and the intracellular transport of organelles. Myotilin, palladin and myopalladin form a small family of proteins containing immunoglobulin-like (Igl) domains. They are associated with the actin cytoskeleton, and all members of the family are suggested to have roles as a scaffold and as regulators of actin organization. Myotilin and myopalladin are expressed as a single isoform only in the striated muscle. Myotilin expression level is higher in the skeletal muscle than in the heart, while myopalladin expression in higher in the heart than in the skeletal muscle. Their expression levels might be directly correlated with their function. On the contrary, the palladin gene gives rise to several palladin isoforms expressed as a result of alternative splicing events. Palladin is expressed not only in the striated muscle but also in other tissue types, such as the nervous tissue, and different isoforms apparently play cell-specific roles. The three members of the family are localized at the Z-disk in the striated muscle and here they have a common binding partner, the bona-fide Z-disk protein, alpha-actinin. Point mutations in myotilin gene causes muscle disorders of variable phenotype: limb-girdle muscular dystrophy A (LGMD1A), myofibrillar myopathy (MFM) and spheroid body myopathy (SBM). On the other hand, palladin gene mutation has been reported to be associated with familial pancreatic cancer and increased risk for myocardial infarction. In this study we found that, as shown for other poly-L-proline-containing proteins, palladin directly binds a key molecule involved in actin dynamics, profilin. Profilin has a dual function: it is a promoter of actin assembly and it can also act as an actin-sequestring protein resulting in actin depolymerisation. Palladin was shown to interact with profilin via its second polyproline region and, further more, we demonstrated that the interaction is highly dynamic and of low affinity. In cells, palladin colocalized with profilin in actin-rich bundles near cell edges. These results indicate that 90-92 kDa palladin associates with profilin in regions in which novel actin filaments form and that palladin may be involved in the coordination of actin filament formation. Alpha-actinin, an important actin cross-linking molecule, connects the cytoskeleton to transmembrane proteins and serves as a scaffold for signalling molecules. We found that palladin binds to and colocalize with alpha-actinin. The interaction is mediated via a highly conserved region in both myotilin and palladin which is considered as a new binding domain for alpha-actinin. Pain, stiffness and tenderness in the muscle, or delayed onset muscle soreness (DOMS) appears in untrained persons who perform eccentric exercise. All aspects of DOMS are not yet fully understood, however it is considered that new sarcomeres are formed. This process includes modifications in the Z-disk architecture and composition, such as temporary loss of -actinin, titin and nebulin and polymerization of G-actin to form foci of increased F-actin labelling in skeletal muscle fibers after the exercise to finally result in supranumerary sarcomeres. Our studies showed that myotilin follows the widened distribution patterns observed for F-actin, suggesting that myotilin acts as a cross-linker and an F-actin stabilizer. In these structures, myotilin is probably replacing alpha-actinin and, similarly with alpha-actinin, might be an anchoring site for signalling or scaffolding molecules that are recruited to drive the formation of the new sarcomeres. We propose myotilin as a guardian of the Z-disk as apparently myotilin contributes to actin organization in both mature and forming Z-disks. To further study the functions of myotilin we generated knockout mice. While loss of all palladin isoforms leads to embryonical lethality in mice, we showed that myotilin knockout mouse survives and has no obvious morphological or functional alteration in striated muscle or other organs. Myotilin absence is apparently compensated by other proteins, possibly by members of myotilin/palladin/myopalladin subfamily. This finding is in concordance with the finding that the transgenic expression of a mutant myotilin leads to morphological alterations observed in myotilinopathies, i.e. mutated myotilin appears to have a toxic effect on the structure of the skeletal muscle, whereas myopathy due to myotilin deficiency has not been reported. Further, we have generated and investigated a mouse that lacks myotilin and expresses low levels of the 200 kDa palladin. While the 200 kDa palladin hypomorph mice shows ultrastructural modifications of the heart architecture, we showed that combined absence of myotilin and low levels of 200 kDa palladin led to morphological and functional alterations in skeletal muscle. This work showed that 200 kDa palladin has an important role in the maintenance of normal architecture of the cardiomyocytes and that myotilin deficiency apparently exacerbated the cardiomyocyte defects. This indicates that in skeletal muscle myotilin and 200 kDa palladin may have a similar function, while in the heart their functions might be different.
  • Bister, Ville (Helsingin yliopisto, 2007)
    Matrix metalloproteinases (MMPs) comprise a family of 23 zinc-dependent human endopeptidases that can degrade virtually all components of the extracellular matrix (ECM). They are classified into eight subgroups according to their structure and into six subgroups based on their substrate-specificity. MMPs have been implicated in inflammation, tissue destruction, cell migration, arthritis, vascular remodeling, angiogenesis, and tumor growth and invasion. MMPs are inhibited by their natural inhibitors, tissue inhibitors of metalloproteinases (TIMPs). Different MMPs function in the same tasks depending on the tissue or cancer subtype. I investigated the role of recently discovered MMPs, especially MMPs-19 and -26, in intestinal inflammation, in intestinal and cutaneous wound healing, and in intestinal cancer. Several MMPs and TIMPs were studied to determine their exact location at tissue level and to obtain information on possible functions of MMPs in such tissues and diseases as the healthy intestine, inflammatory bowel disease (IBD), neonatal necrotizing enterocolitis (NEC), pyoderma gangrenosum (PG), and colorectal as well as pancreatic cancers. In latent celiac disease (CD), I attempted to identify markers to predict later onset of CD in children and adolescents. The main methods used were immunohistochemistry, in situ hybridization, and Taqman RT-PCR. My results show that MMP-26 is important for re-epithelialization in intestinal and cutaneous wound healing. In colon and pancreatic cancers, MMP-26 seems to be a marker of invasive potential, although it is not itself expressed at the invasive front. MMP-21 is upregulated in pancreatic cancer and may be associated with tumor differentiation. MMPs-19 and -28 are associated with normal tissue turnover in the intestine, but they disappear in tumor progression as if they were protective markers . MMP-12 is an essential protease in intestinal inflammation and tissue destruction, as seen here in NEC and in previous CD studies. In patients with type 1 diabetes (T1D), MMPs-1, -3, and -12 were upregulated in the intestinal mucosa. Furthermore, MMP-7 was strongly elevated in NEC. In a model of aberrant wound repair, PG, MMPs-8, -9, and 10 and TNFα may promote ECM destruction, while absence of MMP-1 and MMP-26 from keratinocytes retards re-epithelialization. Based on my results, I suggest MMP-26 to be considered a putative marker for poor prognosis in pancreatic and colon cancer. However, since it functions differently in various tissues and tumor subtypes, this use cannot be generalized. Furthermore, MMP-26 is a beneficial marker for wound healing if expressed by migrating epithelial cells. MMP-12 expression in latent CD patients warrants research in a larger patient population to confirm its role as a specific marker for CD in pathologically indistinct cases. MMP-7 should be considered one of the most crucial proteases in NEC-associated tissue destruction; hence, specific inhibitors of this MMP are worth investigating. In PG, TNFα inhibitors are potential therapeutic agents, as shown already in clinical trials. In conclusion, studies of several MMPs in specific diseases and in healthy tissues are needed to elucidate their roles at the tissue level. MMPs and TIMPs are not exclusively destructive or reparative in tissues. They seem to function differently in different tissues. To identify selective MMP inhibitors, we must thoroughly understand the MMP profile (degradome) and their functions in various organs not to interfere with normal reparative functions during wound repair or beneficial host-response effects during cancer initiation and growth.
  • Kallio, Suvi (Helsingin yliopisto, 2009)
    Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Both environmental factors and several predisposing genes are required to generate MS. Despite intensive research these risk factors are still largely unknown, the pathogenesis of MS demyelination is poorly understood, and no curative treatment exists. Both prevalence and familial occurrence of MS are exceptionally high in a Finnish population subisolate, Southern Ostrobothnia, presumably due to enrichment of predisposing genetic variants within this region. Previous linkage scan on MS pedigrees from Southern Ostrobothnia detected three main MS loci on chromosomes 5p, 6p (HLA) and 17q. Linkage studies in other populations have also provided independent evidence for the location of MS susceptibility genes in these regions. Further, these loci are syntenic to the experimental autoimmune encephalomyelitis (EAE) susceptibility loci of rodents. In this thesis work an effort was made to localize MS predisposing alleles of the linked loci outside the HLA region by studying familial MS cases from the Southern Ostrobothnia isolate. Analysis of the 5p locus revealed one region, flanking the complement component 7 (C7) gene. The identified relatively rare haplotype seems to have a fairly large effect on genetic susceptibility of MS (frequency MS 12%, controls 4%; p=0.000003, OR=2.73). Evidence for association with alleles of the region and MS was seen also in more heterogeneous populations. Convincingly, plasma C7 protein levels and complement activity correlated with the risk haplotype identified. The finding stimulated us to study other complement cascade genes in MS. No evidence for association could be observed with the complement component coding genes outside 5p. A scan of the 17q locus provided evidence for association with variants of the protein kinase C alpha (PRKCA) gene (p=0.0001). Modest evidence for association with PRKCA was observed also in Canadian MS families. Finally we used a candidate gene based approach to identify potential MS loci. Mutations of DAP12 and TREM2 cause a recessively inherited CNS white matter disease PLOSL. Interestingly, DAP12 and TREM2 are located in MS regions on 6p and 19q, and we tested them as potential candidate genes in the Finnish MS sample. No evidence for association with MS was observed. This thesis provides an example of how extended families from special populations can be utilized in fine-mapping of the linked loci. A first relatively rare MS variant was identified utilizing the strength of a Finnish population subisolate. This variant seems to have an effect on activity of the complement system, which has previously been suggested to have an important role in the pathogenesis of MS.
  • Lundán, Tuija (University of Helsinki, 2008)
    Chronic myeloid leukemia (CML) is a malignant clonal blood disease that originates from a pluripotent hematopoietic stem cell. The cytogenetic hallmark of CML, the Philadelphia chromosome (Ph), is formed as a result of reciprocal translocation between chromosomes 9 and 22, which leads to a formation of a chimeric BCR-ABL fusion gene. The BCR-ABL protein is a constitutively active tyrosine kinase that changes the adhesion properties of cells, constitutively activates mitogenic signaling, enhances cell proliferation and reduces apoptosis. This results in leukemic growth and the clinical disease, CML. With the advent of targeted therapies against the BCR-ABL fusion protein, the treatment of CML has changed considerably during the recent decade. In this thesis, the clinical significance of different diagnostic methods and new prognostic factors in CML have been assessed. First, the association between two different methods for measuring CML disease burden (the RQ-PCR and the high mitotic index metaphase FISH) was assessed in bone marrow and peripheral blood samples. The correlation between positive RQ-PCR and metaphase FISH samples was high. However, RQ-PCR was more sensitive and yielded measurable transcripts in 40% of the samples that were negative by metaphase FISH. The study established a laboratory-specific conversion factor for setting up the International Scale when standardizing RQ-PCR measurements. Secondly, the amount of minimal residual disease (MRD) after allogeneic hematopoietic stem cell transplantation (alloHSCT) was determined. For this, metaphase FISH was done for the bone marrow samples of 102 CML patients. Most (68%), had no residual cells during the entire follow-up time. Some (12 %) patients had minor (<1%) MRD which decreased even further with time, whereas 19% had a progressive rise in MRD that exceeded 1% or had more than 1% residual cells when first detected. Residual cells did not become eradicated spontaneously if the frequency of Ph+ cells exceeded 1% during follow-up. Next, the impact of deletions in the derivative chromosome 9, was examined. Deletions were observed in 15% of the CML patients who later received alloHSCT. After alloHSCT, there was no difference in the total relapse rate in patients with or without deletions. Nor did the estimates of overall survival, transplant-related mortality, leukemia-free survival and relapse-free time show any difference between these groups. When conventional treatment regimens are used, the der(9) status could be an important criterion, in conjunction with other prognostic factors, when allogeneic transplantation is considered. The significance of der(9) deletions for patients treated with tyrosine kinase inhibitors is not clear and requires further investigation. In addition to the der(9) status of the patient, the significance of bone marrow lymphocytosis as a prognostic factor in CML was assessed. Bone marrow lymphocytosis during imatinib therapy was a positive predictive factor and heralded optimal response. When combined with major cytogenetic response at three months of treatment, bone marrow lymphocytosis predicted a prognostically important major molecular response at 18 months of imatinib treatment. Although the validation of these findings is warranted, the determination of the bone marrow lymphocyte count could be included in the evaluation of early response to imatinib treatment already now. Finally, BCR-ABL kinase domain mutations were studied in CML patients resistant against imatinib treatment. Point mutations detected in the kinase domain were the same as previously reported, but other sequence variants, e.g. deletions or exon splicing, were also found. The clinical significance of the other variations remains to be determined.
  • Peltonen, Lauri (Helsingfors universitet, 2008)
    Polylactic- and polyglycolic acid-based degradable biomaterials are in wide clinical use especially in orthopedic and craniomaxillofacial surgery, and in general they have proved to be safe and well-tolerated implant materials. Thus far, they have not been used in reconstructive human middle ear surgery. Common problems related to implant surgery are microbial biofilm formation on medical implants in vivo and subsequent infection. A postoperative implant infection often leads to re-operation and implant removal. The present thesis clarifies the surface properties of polylactic-glycolic acid (PLGA) in relation to bacterial adherence—the first step in biofilm formation—and the biocompatibility of the material in the middle ear. Furthermore, a new application has been studied for imaging of the middle ear with a lower radiation dose than with the present computed tomography (CT) of the ear. This method, cone-beam computed tomography (CBCT), has been used particularly in dental and maxillofacial imaging, where it allows accurate, 3D imaging of a defined area. The first two studies of this thesis tested in vitro adherence of two common pathogens of a chronically or postoperatively infected ear, Staphylococcus aureus and Pseudomonas aeruginosa, onto the surfaces of PLGA and of two common implant materials used in ear surgery: silicone and titanium. In addition, the effect of albumin coating on adherence to these materials was tested and compared. Next, applicability of the PLGA material to reconstructive middle ear surgery was explored by study of its biocompatibility in the middle ear in an animal model in which chinchillas were operated on, followed-up, and killed at 6 months postoperatively. Biocompatibilities of the implanted materials were evaluated according to clinical and histological findings. Suitability of the CBCT for imaging of the ear was tested by imaging human cadaver temporal bones and comparing scaled accuracies of the images created by CBCT with those constructed with traditional multislice helical CT. There proved to be no more bacterial adherence in vitro to the PLGA materials tested than to silicone and titanium. Albumin coating significantly reduced bacterial adherence to every material tested. The biocompatibility of PLGA in the middle ear of the chinchilla was very good. In histological samples, only a mild inflammatory reaction was evident around the degrading PLGA plates. Clinically, no infections or extrusion of the implanted material occurred. Limited CBCT was found to be at least as accurate as conventional multislice helical CT in showing the clinically and surgically important landmarks of the middle and inner ear. The effective radiation dose was essentially lower with the CBCT than with the helical CT used in this study. Visualization of the middle ear structures and implants of operated temporal bones was clear and of diagnostic value. Based on the results of the thesis, it can be concluded that PLGA is a safe and well-tolerated implant material in the middle ear area, and there is no greater in vitro adherence of S. aureus and P. aeruginosa to PLGA surfaces than to titanium and silicone. In addition, coating of these materials with albumin means that adherence of the bacteria to their surfaces can be substantially reduced, suggesting that this method may be useful in implant surgery as a preventive maneuver against postoperative infections. Furthermore, CBCT seems to be a promising new method for imaging the structures of the temporal bone. The diagnostic accuracy of CBCT corresponds to that of helical CT, while the radiation dose to patient per investigation remains lower with CBCT. Focused imaging with the lesser radiation exposure expands the possibilities for imaging the ear, especially when follow-up and limited uni- or bilateral examination is needed.
  • Moore, Henna (2013)
    The nucleolus is a subnuclear structure governing ribosome biogenesis. In the past few years there has been increasing evidence that in addition to function as a ribosome factory the nucleolus bears several other cellular functions, including regulation of tumor suppressor and oncogene activities, and sensing cellular and proteotoxic stress. Alterations in nucleolar structures and protein localization are indicative of changes in nucleolar function. When exposed to certain types of cellular stress, the nucleolar structure is disrupted and the localization of several nucleolar proteins is reorganized. This process, nucleolar stress, leads to the stabilization of the tumor suppressor protein p53. In this thesis work, we used quantitative proteomics of isolated nucleoli and dynamic imaging of live cells to explore the changes in localization of nucleolar proteins in response to various types of cellular stress, including ultraviolet (UV) and ionizing radiation (IR). Furthermore, we used fluorescent photobleaching and biochemical analyses of nucleoli to study nucleolar and nucleolus-associated proteins in cells exposed to UV radiation and proteasomal stress. We found that nucleolar substructures and the nucleolar proteome underwent extensive reorganization in response to UV damage whereas the responses to IR were more limited. These results were supported by concurrent repression of RNA polymerase I (RNA Pol I) transcription that we observed in UV but not in IR treated cells. However, proteomic analysis imminently after the IR insult revealed that IR caused a rapid and transient response in certain DNA repair proteins and RNA Pol I components. Although these responses were not extensive, they were significant and likely relevant in the early cellular response to IR. We also identified a novel nucleolar stress body, which we named nucleolus-associated RNA-protein aggregate (NoA). It formed by the inhibition of proteasomal activity and contained conjugated ubiquitin, polyadenylated RNA and numerous nuclear proteasomal target proteins, including cellular regulators, key players in oncogenesis and stress response proteins. The formation of NoA was dependent on ubiquitin availability as it was rescued by promoting ubiquitin recycling. Interestingly, the inhibition of chromosome region maintenance 1 protein homolog (CRM1)-dependent nuclear export further promoted the formation of NoA. These results suggest that the nucleolar activities are linked with the proteasomal function, and surveillance of RNA and nuclear proteasomal target proteins. Finally, we found that proteasomal activity was required for the nucleolar responses of nucleophosmin (NPM) and other granular component (GC) proteins in cells exposed to UV radiation. These results support the role of the nucleolus as a sensitive stress responder and suggest a role for the proteasome in nucleolar activities.
  • Winter, Torsten (Helsingin yliopisto, 2004)
  • Mustelin, Linda (Helsingin yliopisto, 2012)
    Background: Obesity is one of the leading causes of ill-health in the Western world, and physical inactivity is a known risk factor for obesity. Obesity as well as physical activity and cardiorespiratory fitness are influenced by both genetic and environmental factors. However, whether they share the same genetic vs. environmental etiology has rarely been studied. Aims: To explore the relative contributions of genetic and environmental factors on body mass index (BMI), waist circumference, physical activity and cardiorespiratory fitness, to explore whether physical activity modifies the relative contribution of genetic factors on BMI and waist circumference and to assess the effects of obesity on cardiorespiratory fitness and expression of genes of mitochondrial oxidative phosphorylation in young adult twins. Subjects: 4,798 twins born in 1975 - 1979 (FinnTwin16 cohort) and followed up from the ages of 16 to 23 - 27 years; two subsamples of the FinnTwin16 cohort: one consisting of 24 monozygotic (MZ) pairs concordant and discordant for obesity and the other consisting of 152 MZ and DZ (dizygotic) twin pairs selected to represent a wide range of intra-pair differences in BMI; 1,294 twins born in 1983 - 1987 and followed up from the ages of 11 - 12 to 20 - 25 years (FinnTwin12 cohort). Measures: Cohorts: Self-reported height, weight and waist circumference, a physical activity index calculated from the product of self-reported physical activity intensity, duration and frequency, the Baecke physical activity questionnaire. Subsamples: Measured height, weight and waist circumference, measured body composition and insulin sensitivity, cardiorespiratory fitness, gene expression in adipose tissue. Results: Physical activity decreased the influence of genetic factors on BMI and waist circumference. The association between sports activity and obesity and of that between sports activity and cardiorespiratory fitness was largely due to genetic factors influencing both traits. Genetic factors contributed significantly to individual differences in physical activity, with genetic factors explaining between 41% and 64% of the variance in four physical activity indexes. Acquired obesity was associated with poor cardiorespiratory fitness and lowered transcript levels of genes involved in mitochondrial function in adipose tissue. Conclusions: The influence of genetic factors on obesity measures was smaller in physically active subjects as compared to inactive subjects indicating a geneenvironment association between physical activity and genes predisposing to obesity. This suggests that the individuals at greatest genetic risk for obesity would benefit most from physical activity. Genetic factors influence both would benefit most from physical activity. Genetic factors influence both physical activity and obesity traits and explain a major part of their relationships. Acquired obesity causes poor cardiorespiratory fitness, insulin resistance and downregulation of genes involved in mitochondrial function.
  • Saarni, Suoma (Helsingfors universitet, 2008)
    Overweight and obesity have become more prevalent during the last decades; more than half of the western population is now overweight and a fifth obese. Especially among adolescents has the increase in overweight prevalence been rapid. Overweight combined with a large waist circumference (i.e. abdominal obesity) and smoking increase the morbidity of cardiovascular disease, metabolic diseases, like diabetes, and many cancers. Obesity and smoking are two leading causes of preventable death in developed countries. Paralleling the escalating trends in obesity, dieting and especially health compromising dieting methods, including smoking motivated by weight control reasons, are becoming more prevalent. Dieting for rapid weight loss usually leads to weight regain with possible extra pounds and detrimental effects in fat distribution or other health measures. Three quarters of those with intentional weight loss more than 5 kg reports regaining it all. Smoking and dieting seem to be intertwined with the way that they affect the development of overweight and obesity. In this study the effects of recurrent dieting and smoking on body weight were examined. In addition the effect of smoking on the development of abdominal obesity was studied. A further aim was to clarify how strongly smoking and recurrent dieting are associated among Finnish men and women at different ages. Three different data sets were used in this study. FinnTwin16 consists of virtually all twins born between 1975 and 1979 (N=5563), surveyed at ages 16, 17, 18.5 and 24 years. The Finnish Twin Cohort includes 12 793 same-sex twins born between 1930 and 1957 surveyed in 1990. The Cohort of male elite athletes consists of 1838 athletes and 834 matched referents surveyed at 1985, 1995 and 2001. Self-reported height, weight and smoking are included in all questionnaires. Dieting behaviour was self-reported in twin data and based on sport among athletes. It is known that recurrent dieting with regains is common among sportsmen in sports with weight classes like boxing and wrestling. Smoking in adolescence predicted later abdominal obesity in both sexes and overweight among women. Recurrent dieting among men was found to predispose for later weight gain and obesity. Smoking was associated with recurrent dieting among young men and women, but among older men the association was the opposite. Smoking prevention and discouragement of unnecessary dieting might be more effective tools against later morbidity associated with obesity and abdominal obesity than previously thought.
  • Roos, Eira (Helsingin yliopisto, 2014)
    Obesity and overweight are common among working aged population. Obesity is associated with a number of long-term illnesses as well as increased mortality. Previous studies have found that obesity is also associated with some forms of work disability. However, longitudinal studies with register-based large data sets are scarce. The aim of this study was to examine the association between working conditions and subsequent weight gain as well as the associations between body weight, weight change and subsequent work disability in a cohort setting among middle-aged employees. This study is part of Helsinki Health Study (HHS), a cohort study on employees of the City of Helsinki. The data consists of a baseline mail questionnaire survey sent in 2000-2002 to 40-, 45-, 50-, 55- and 60-year old employees (respondents n=8960) and a follow-up questionnaire survey sent to the respondents of the baseline survey in 2007 (respondents n=7332). Questionnaire surveys yielded data on a wide range of factors such as socio-economic determinants, health and working conditions. The data from the surveys were combined with data from health check-ups that were carried out among the employees of the City of Helsinki during 2000-2002. The data were additionally linked with register data on employees sickness absence spells and disability retirements from the Finnish Centre for Pensions. Logistic regression analyses, the Cox proportional hazards model and Poisson regression analyses were used as statistical methods. A number of confounding factors were controlled for the analysis, including working conditions, health behaviours, previous health, and physical and mental functioning. Weight gain was common as one in four employees experienced major weight gain during the 5-7 year follow-up. For most of the studied working conditions, no association with weight gain was observed. Night shift work, work that was characterized as having hazardous exposures, passive work, and work where facing physical violence or threats was common were weakly associated with major weight gain. Both obesity and weight change (even among normal-weight employees) were associated with subsequent sickness absence. Obesity increased the risk of long spells of sickness absence in particular, but also elevated the risk of short spells. Weight loss, weight gain and stable obesity increased the risk of sickness absence spells of all lengths. Obesity was strongly associated with disability retirement due to musculoskeletal diseases, and to a lesser degree to mental disorders and other causes. Following adjustment for earlier health, working conditions and functioning, the association between obesity and long sickness absence spells and disability retirement was somewhat attenuated. The results of this study show that weight gain is common among middle-aged employees and that the studied working conditions are weakly or not at all associated with weight gain. The findings also indicate that weight gain and obesity are clearly and consistently associated with both temporary and permanent work disability. Obesity is thus not only a public health issue but also affects occupational health and work ability. Prevention of obesity and weight gain is increasingly important in primary health care as well as in occupational health care.
  • Lehtovirta, Päivi (Helsingin yliopisto, 2007)
    The purpose of the present study was to examine the outcome of pregnancies among HIV-infected women in Helsinki, use of the levonorgestrel-releasing intrauterine system (LNG-IUS) among HIV-infected women and the prevalence and risk factors of cytological and histologically proven cervical lesions in this population. Between 1993 and 2003 a total of 45 HIV-infected women delivered 52 singleton infants. HIV infection was diagnosed during pregnancy in 40% of the mothers. Seventeen of the mothers received antiretroviral (ARV) medication prior to pregnancy and in 34 cases, the medication was started during pregnancy. A good virological response (i.e. HIV RNA load <1000/mL during the last trimester) to ARV medication was achieved in 36/40 (90%) of the patients in whom HI viral load measurements were performed. Of the infants, 92% were born at term, and their mean (±SD) birth weight was 3350±395 g. The Caesarean section rate was low, 25%. All newborns received ARV medication and none of the infants born to mothers with pre-delivery diagnosis of maternal HIV infection were infected. The safety and advantages of the LNG-IUS were studied prospectively (n=12) and retrospectively (n=6). The LNG-IUS was well tolerated and no cases of PID or pregnancy were noted. Menstrual bleeding was reduced significantly during use of the LNG-IUS; this was associated with a slight increase in haemoglobin levels. Serum oestradiol concentrations remained in the follicular range in all subjects. The key finding was that genital shedding of HIV RNA did not change after the insertion of the LNG-IUS. The mean annual prevalence of low-grade squamous intraepithelial lesions (SIL) was 15% and that of high-grade SIL was 5% among 108 systematically followed HIV-infected women during 1989 2003. A reduced CD4 lymphocyte count was associated with an increased prevalence of SIL, whereas duration of HIV infection, use of ARV medication and HI viral load were not. The cumulative risk of any type of SIL was 17% after one year and 48% after five years among patients with initially normal Pap smears. The risk of developing SIL was associated with young age and a high initial HI viral load. During the follow-up 51 subjects (n=153) displayed cervical intraepithelial neoplasia (CIN), (16% CIN1 and 18% CIN 2-3). Only one case of cancer of the uterine cervix was detected. Pap smears were reliable in screening for CIN. Both nulliparity (p<0.01) and bacterial vaginosis (p<0.04) emerged as significant risk factors of CIN. In conclusion, a combination of universal antenatal screening and multidisciplinary management allows individualized treatment and prevents vertical transmission of HIV. Use of the LNG-IUS is safe among HIV-infected women and cervicovaginal shedding of HIV RNA is not affected by use of the LNG-IUS. The risk of cervical pre-malignant lesions is high among HIV-infected women despite systematic follow-up.
  • Kreivi, Hanna-Riikka (Helsingin yliopisto, 2013)
    The prevalence of snoring is high and snoring affects one s quality of life. Snoring can also be a symptom of obstructive sleep apnea (OSA). Snoring has traditionally been measured to predict OSA, but it has not been quantified in the same way as sleep disordered breathing events are. The objective diagnosis of snoring requires a sleep study. Simple and cost-effective systems are needed to screen for snoring and OSA. Upper airway symptoms are frequent in snorers and patients with obstructive sleep apnea syndrome (OSAS) already prior any treatment. The treatment of choice for obstructive sleep apnea is continuous positive airway pressure (CPAP). Although CPAP treatment is effective for OSA, the challenge is to improve treatment adherence. To evaluate the value of a Moving Picture Experts Group Layer-3 Audio (MP3) recorder device in screening of snoring, we recorded snoring sounds during polysomnography (PSG) in 200 consecutive patients referred for suspected obstructive sleep apnea (OSA). Snoring was recorded during the PSG with two microphones and with the MP3 device. We compared the results of the MP3 snoring recordings to the snoring recordings in PSG. To investigate the frequency of upper airway symptoms in subjects referred for a sleep study, we enrolled 524 consecutive patients and asked them to complete a questionnaire inquiring about current upper airway symptoms and any history of nasal and pharyngeal disorders prior the sleep study. Moreover, we examined 385 consecutive OSAS patients referred for CPAP initiation and ask the patients to complete questionnaires about upper airway symptoms before beginning CPAP and after two months of CPAP treatment. To evaluate predictors of later CPAP use, we finally followed 580 consecutive OSA patients scheduled for CPAP initiation for one year. Patients completed a self-efficacy questionnaire (5 = low, 25 = high score) before CPAP initiation. Immediately after CPAP initiation, we asked about the patients satisfaction with the CPAP trial as well as their eagerness and willingness to continue CPAP therapy (0 = unsatisfied, uneager or refused CPAP, 100 = satisfied, eager or willing to continue CPAP treatment). MP3 recording was technically successful for 87% of the patients. The Pearson correlation between PSG snoring and MP3 snoring was significant at 0.77 (p PIENEMPI 0.001). More than half of the sleep study subjects suffered from throat, mouth and nose dryness as well as from nasal stuffiness. The patients with moderate or severe OSAS (apnea-hypopnea index ≥ 15 and an Epworth sleepiness scale score ≥ 10) more often experienced mouth dryness (71% vs. 40%, p PIENEMPI 0.01) than did those with mild or no OSAS. In addition, patients with moderate to severe OSAS who were beginning CPAP treatment frequently suffered daily or almost daily from upper airway symptoms: dryness of mouth (61%), throat (54%) and nose (51%), nasal stuffiness (52%), sneezing (30%), mucus in the throat (24%), rhinorrhea (17%), and nose bleeds (6%). In CPAP users there was shown a significant reduction in the number of patients with frequent mouth (37%), throat (34%) and nose (28%) dryness and nasal stuffiness (24%). Finally, of the 580 patients 377 (65%) continued CPAP therapies beyond one year. Altogether 77 patients had a low score (< 50) for willingess to continue CPAP treatment after a brief initiation, and only 7 of them used CPAP > four hours daily after one year, yielding a specificity of 97% in predicting CPAP failure. In conclusion, recording snoring with an MP3 device offers reliable information about the patients snoring. Subjects referred for a sleep study often presented with upper airway symptoms. Nasal stuffiness and airway dryness in particular bothered snorers even before the development of sleep apnea. The most common upper airway symptoms in patients with untreated OSAS were associated with mucosal dryness. These symptoms improved during CPAP treatment. Finally, a low score for willingness to continue CPAP therapy after a short trial predicted CPAP failure and poor CPAP adherence after one year.
  • Keski-Säntti, Petra (Helsingin yliopisto, 2011)
    The occurrence of occupational chronic solvent encephalopathy (CSE) seems to decrease, but still every year reveals new cases. To prevent CSE and early retirement of solvent-exposed workers, actions should focus on early CSE detection and diagnosis. Identifying the work tasks and solvent exposure associated with high risk for CSE is crucial. Clinical and exposure data of all the 128 cases diagnosed with CSE as an occupational disease in Finland during 1995-2007 was collected from the patient records at the Finnish Institute of Occupational Health (FIOH) in Helsinki. The data on the number of exposed workers in Finland were gathered from the Finnish Job-exposure Matrix (FINJEM) and the number of employed from the national workforce survey. We analyzed the work tasks and solvent exposure of CSE patients and the findings in brain magnetic resonance imaging (MRI), quantitative electroencephalography (QEEG), and event-related potentials (ERP). The annual number of new cases diminished from 18 to 3, and the incidence of CSE decreased from 8.6 to 1.2 / million employed per year. The highest incidence of CSE was in workers with their main exposure to aromatic hydrocarbons; during 1995-2006 the incidence decreased from 1.2 to 0.3 / 1 000 exposed workers per year. The work tasks with the highest incidence of CSE were floor layers and lacquerers, wooden surface finishers, and industrial, metal, or car painters. Among 71 CSE patients, brain MRI revealed atrophy or white matter hyperintensities or both in 38% of the cases. Atrophy which was associated with duration of exposure was most frequently located in the cerebellum and in the frontal or parietal brain areas. QEEG in a group of 47 patients revealed increased power of the theta band in the frontal brain area. In a group of 86 patients, the P300 amplitude of auditory ERP was decreased, but at individual level, all the amplitude values were classified as normal. In 11 CSE patients and 13 age-matched controls, ERP elicited by a multimodal paradigm including an auditory, a visual detection, and a recognition memory task under single and dual-task conditions corroborated the decrease of auditory P300 amplitude in CSE patients in single-task condition. In dual-task conditions, the auditory P300 component was, more often in patients than in controls, unrecognizable. Due to the paucity and non-specificity of the findings, brain MRI serves mainly for differential diagnostics in CSE. QEEG and auditory P300 are insensitive at individual level and not useful in the clinical diagnostics of CSE. A multimodal ERP paradigm may, however, provide a more sensitive method to diagnose slight cognitive disturbances such as CSE.
  • Ojajärvi, Anneli (Helsingin yliopisto, 2006)
    Objective and background. Tobacco smoking, pancreatitis and diabetes mellitus are the only known causes of pancreatic cancer, leaving ample room for yet unidentified determinants. This is an empirical study on a Finnish data on occupational exposures and pancreatic cancer risk, and a non-Bayesian and a hierarchical Bayesian meta-analysis of data on occupational factors and pancreatic cancer. Methods. The case-control study analyzed 595 incident cases of pancreatic cancer and 1,622 controls of stomach, colon, and rectum cancer, diagnosed 1984-1987 and known to be dead by 1990 in Finland. The next-of-kin responded to a mail questionnaire on job and medical histories and lifestyles. Meta-analysis of occupational risk factors of pancreatic cancer started off with 1,903 identified studies. The analyses were based on different subsets of that database. Five epidemiologists examined the reports and extracted the pertinent data using a standardized extraction form that covered 20 study descriptors and the relevant relative risk estimates. Random effects meta-analyses were applied for 23 chemical agents. In addition, hierarchical Bayesian models for meta-analysis were applied to the occupational data of 27 job titles using job exposure matrix as a link matrix and estimating the relative risks of pancreatic cancer associated with nine occupational agents. Results. In the case-control study, logistic regressions revealed excess risks of pancreatic cancer associated with occupational exposures to ionizing radiation, nonchlorinated solvents, and pesticides. Chlorinated hydrocarbon solvents and related compounds, used mainly in metal degreasing and dry cleaning, are emerging as likely risk factors of pancreatic cancer in the non-Bayesian and the hierarchical Bayesian meta-analysis. Consistent excess risk was found for insecticides, and a high excess for nickel and nickel compounds in the random effects meta-analysis but not in the hierarchical Bayesian meta-analysis. Conclusions. In this study occupational exposure to chlorinated hydrocarbon solvents and related compounds and insecticides increase risk of pancreatic cancer. Hierarchical Bayesian meta-analysis is applicable when studies addressing the agent(s) under study are lacking or very few, but several studies address job titles with potential exposure to these agents. A job-exposure matrix or a formal expert assessment system is necessary in this situation.
  • Airaksinen, Liisa (Helsingin yliopisto, 2010)
    Occupational rhinitis is mainly caused by work environment and not by stimuli encountered outside the workplace. It differs from rhinitis that is worsened by, but not mainly caused by, workplace exposures. Occupational rhinitis can develop in response to allergens, inhaled irritants, or corrosive gases. The thesis evaluated the use of challenge tests in occupational rhinitis diagnostics, studied the long-term health-related quality of life among allergic occupational rhinitis patients, and the allergens of wheat grain among occupational respiratory allergy patients. The diagnosed occupational rhinitis was mainly allergic rhinitis, which was caused by occupational agents, most commonly flours and animal allergens. The non-IgE-mediated rhinitis reactions were less frequent and caused more often asthma than rhinitis. Both nasal challenges and inhalation challenges were found to be safe tests. The inhalation challenge tests had considerably resource-intensive methodology. However, the evaluation of nasal symptoms and signs together with bronchial reactions saved time and expense compared with the organization of multiple individual challenges. The scoring criteria used matched well with the weighted amount of discharge ≥ 0.2 g and in most cases gave comparable results. The challenge tests are valuable tools when there is uncertainty whether the patient's exposure should be reduced or discontinued. It was found that continuing exposure decreases health-related quality of life among patients with allergic occupational rhinitis despite of rhinitis medications, still approximately ten years after the diagnosis. Health-related quality of life among occupational rhinitis patients without any longer occupational exposure was mainly similar than that of the healthy controls. This highlights the importance of the reduction and cessation of occupational exposure. To achieve this, 17% of occupational rhinitis patients had been re-educated. Alpha-amylase inhibitors, lipid transfer protein 2G, thaumatin -like protein, and peroxidase I were found to be relevant allergens in Finnish patients with occupational respiratory wheat allergy. Of these allergens, thaumatin-like protein and lipid transfer protein 2G were found as new allergens associated with baker's rhinitis and asthma. The knowledge of the new clinically relevant proteins can be used in the future in the development of better standardized diagnostic preparations.