Lääketieteellinen tiedekunta

 

Recent Submissions

  • Juola, Anna-Liisa (Helsingin yliopisto, 2018)
    Abstract Educationally intervening the use of potentially harmful medication among residents in institutional settings Institutionalized older people are frail, they suffer from a high number of comorbidities, and polypharmacy is common among them. They are prone to adverse effects of drugs. Aim of this study was to explore the use of potentially harmful medications (PHMs) among older people living in assisted living facilities in Helsinki (Studies 1-4) and nursing homes in Kouvola (Study 1). Study 1 was a cross-sectional study investigating burden and overlapping of PHMs according to three criteria (drugs with anticholinergic properties, use of Beers’ criteria medications, and concomitant use of >2 psychotropics). Proportion of using any PHMs was 79%. Burden of PHMs was associated with lower health-related quality of life (HRQoL), poorer self-rated health, and lower psychological well-being (PWB), but not with increased 3-year mortality. Studies 2-4 were based on a randomized controlled trial (RCT) with educational intervention. Nurses in intervention units received 2x4 hour education in older people medication, both harmful and beneficial. Learning was interactive and problem-based. Nurses brought their residents’ medication problems to treating physicians, who made the changes in medication. As a result of intervention, the mean number of PHMs, especially psychotropics, decreased in intervention wards compared to control wards. Residents in intervention wards had significantly less hospital days/year (relative risk RR 0.60, 95% confidence interval (CI) 0.49 to 0.75; p<0.001), and falls (incidence rate ratio IRR 0.72, 95% CI 0.59 to 0.88; p<0.001) compared to control wards. HRQoL declined more slowly in the intervention wards compared to control wards. There was no difference in 1-year mortality or changes in cognition. Use of PHMs is common among older people living in institutional settings and is associated with lower HRQoL, PWB, and self-rated health. It is possible to reduce the use of PHMs with a quite light educational intervention. As a result residents in intervention wards had less hospital days and falls compared to control wards.
  • Macharey, Georg (Helsingin yliopisto, 2018)
    The cesarean section rate is increasing worldwide and breech presentation is with approximately 17 % one of the major indications for elective cesarean sections. Cesarean section might be a life-saving procedure for mother and child during labor, but is also a major procedure with possible complications and adverse long-term effects for future pregnancies. Breech presentation occurs in 2-3 % of term pregnancies. The safety of vaginal breech delivery has been questioned for a long time, as a trial of vaginal breech labor is associated with an increased adverse short-term outcome. The study was designed to evaluate the potential pathophysiology of breech presentation itself, to look for unidentified risk factors associated with adverse perinatal outcome in vaginal breech deliveryand to investigate if a trial of vaginal labor at term with the fetus in breech position, is associated with adverse neurodevelopmental outcome in the children at the age of four. The breech presentation rate at term in Finland is 2.2 %. Breech presentation is compared with vertex presentation associated with a higher stillbirth rate Breech presentation is compared with vertex presentation associated with a higher stillbirth rate, fetal growth restriction, oligohydramnios, gestational diabetes, congenital fetal abnormalities and a previous cesarean section. The perinatal outcome in induced deliveries compared to spontaneous breech deliveries did not show differences. However, a trial of induced breech labor was associated with a higher intrapartum cesarean section rate compared to spontaneous breech labor. An active second delivery stage lasting less than 40 minutes protects from adverse perinatal outcome. A higher intrapartum cesarean delivery rate of at least 24 % was also associated with a lower rate of adverse outcome. Epidural anesthesia, instead, was associated with a higher risk for adverse neonatal outcome. The study results confirmed fetal growth restriction as a risk factor for adverse perinatal outcome in vaginal breech labor. In addition we found that oligohydramnios, a previous cesarean section, gestational diabetes, epidural anesthesia and nulliparity are associated with a higher risk for adverse peri- and neonatal outcome. The neurological development of children at the age of four years, which were born after a trial of vaginal labor with the fetus in breech presentation, compared to those born by elective cesarean section with the fetus in breech presentation. In conclusion our studies showed that breech presentation at term is more often associated with other clinical factors that are per se markers for possible adverse obstetric risks. We showed that an active second delivery stage lasting less than 40 minutes or a higher intrapartum cesarean section rate of at least 25 % have a protective influence on fetal outcome in a trial of vaginal labor with the fetus in breech presentation. Adverse neonatal outcome in vaginal breech delivery was associated with oligohydramnios, fetal growth restriction, gestational diabetes, previous cesarean delivery, epidural anesthesia and nulliparity. An induction of labor while the fetus is in breech presentation is feasible. There were no differences in the neurological development of children born after a trial of vaginal breech labor at term compared to children, who were born by elective cesarean section while the fetus was in breech presentation.
  • Pirinen, Jani (Helsingin yliopisto, 2018)
    Electrocardiography (ECG) is a routine diagnostic method for all young ischemic stroke (IS) patients, although the relevance of its findings is as yet poorly known. A diagnostic work-up to reveal etiology in a young IS patient includes many cardiac diagnostic methods, as finding a high-risk source of cardioembolism (HRCE) will influence the secondary prevention after IS, and also provides a marker for high risk of recurrent events and mortality. IS per se is a disastrous event, and recurrent cardiovascular events may worsen the situation further. Identifying patients at a high risk of recurrent events is therefore important. The Helsinki Young Stroke Registry (HYSR) includes all 15- to 49-yearold IS patients treated at the Helsinki University Hospital between 1994 and 2007. Blinded to other current clinical data, we analyzed 12-lead resting ECGs obtained 1 to 14 days after IS in 690 patients. We used logistic regression, adjusted for demographic and clinical confounders, to investigate, in 78 patients, what ECG findings are related to an etiology of HRCE (Study I). We investigated what ECG findings bear an increased risk of new cardiovascular events (Study II) and mortality (Study III), using Cox regression adjusted for demographic confounders and comorbidities. We also collected a cohort of stroke-free control subjects in order to study the association of ECG markers with IS at young age, with stratified analysis according to IS subtype (Study IV). Of our IS patient cohort (median age 41 years, 63% male), 35% showed some ECG abnormality. The most common abnormalities were T-wave inversions (16%), left ventricular hypertrophy (LVH) (14%), prolonged P-waves (13%), and prolonged corrected QT interval (QTc) (12%). Of all IS patients, 3% had atrial fibrillation (AF), and 4% P-terminal force in lead V1 (PTF). A longer QRS complex duration, a longer QTc, and wider QRS-T-angle were independently associated with HRCE. Interestingly, PTF had the strongest independent association with HRCE (hazard ratio 43.18). After a median follow-up of 8.8 years, 26.4% of patients experienced some cardiovascular event. 14.6% suffered a recurrent stroke, and 16.1% died; 9.1% died from cardiovascular causes. ECG parameters associated with recurrent cardiovascular events were bundle branch blocks, PTF, LVH, and a broader QRS complex. No ECG parameter was associated with stroke recurrence. A higher heart rate, a shorter P-wave and longer QTc were associated with increased all-cause mortality. Only a higher heart rate was associated with death from cardiovascular causes. In the case-control study, abnormal P-waves, PTF, interatrial block – and combinations of these P-wave abnormalities with LVH – were associated with cardioembolic IS. Abnormal P-wave and IAB were also associated with cryptogenic IS; and LVH was associated with small-vessel disease (SVD) subtype. In conclusion, ECG in young IS patients provides information on IS etiology, risk of recurrent events, and mortality. P-wave abnormalities and ECG markers of LVH are more frequent in young IS patients than in stroke-free controls, suggesting they may be markers of increased IS risk, which is mostly explained by the HRCE subgroup.
  • Parkkola, Anna (Helsingin yliopisto, 2018)
    Type 1 diabetes (T1D) is an immune-mediated disease that affects ~0.7% of children in Finland. Its incidence is the highest in Finland worldwide. The proposed etiology of T1D is both genetic and environmental. Many of these etiological factors are shared between other autoimmune diseases (AIDs) and, accordingly, these diseases co-occur in patients with T1D and their relatives. This thesis aims at characterizing the frequency of additional autoimmunity in Finnish children under the age of 15 years with newly diagnosed T1D and in their extended family members, as well as characterizing the effects of this additional autoimmunity on clinical, metabolic, and genetic markers, and T1D autoantibodies. The subjects for this thesis are participants of the Finnish Pediatric Diabetes Register and Sample Repository. Participating families fill in questionnaires on the clinical parameters, family characteristics, and diabetes and other diseases of the index child and family members. This thesis analysed data from the time of diagnosis on 2245 children diagnosed with T1D between 2002 and 2009. The mean age at diagnosis of T1D for the study population was 7.9 years and the majority were boys (57.1%). For a subset of the cases, follow-up data was available. Additional AIDs were reported by 1.6% children at diagnosis and by 3.2% after a median eight years of follow-up. More than 20% of the families reported first- and/or second-degree relatives with T1D, and over a third, relatives with other AIDs. Fathers were more often affected by T1D compared to mothers (6 vs. 3%), whereas mothers were more often affected by other AIDs (10 vs. 4%). Girls had more often T1D affected paternal and boys T1D affected maternal second-degree relatives. Transient anti-tTG not developing to CD seemed more common among children with T1D than among their relatives. The HLA-DR3-DQ2 haplotype was associated with CD autoimmunity and the HLA-DR4-DQ8 haplotype with familial T1D. Also, non-HLA loci were shown to contribute to the clustering of AIDs in children with multiple AIDs and in autoimmune families. Familial T1D, even with only second-degree relatives affected, leads to less severe onset of T1D in the index child. This thesis provides current estimates of the frequency of additional autoimmunity in Finnish children with newly diagnosed T1D and in their relatives. These figures are in line with those reported previously internationally and in Finland. Novel discoveries were the milder clinical onset of T1D in familial T1D even if only second-degree relatives were affected (readily explained by the increased awareness of the disease in these families), and the gender difference of girls having paternal and boys maternal second-degree relatives affected by T1D. This gender difference, transient anti-tTG among children with T1D at diagnosis, and the reported candidate non-HLA SNPs for clustered autoimmunity require validation by further studies.
  • Szwajda, Agnieszka (Helsingin yliopisto, 2018)
    Genomics-based drug discovery utilizing sequencing data for elucidation of candidate targets has led to the development of a number of successful treatments in the last decades. However, the molecular driver signals for many complex diseases cannot be easily derived from genome sequencing. Functional profiling studies, such as those involving the detection of protein interaction networks or the effects of perturbations with small molecules or siRNAs on cellular phenotypes, offer a complementary approach for the identification of molecular vulnerabilities that can be exploited in the development of new treatment strategies. The goal of this thesis was to develop computational systems biology methods for supporting such functional endeavors, and through their application use cases, to elucidate novel disease driver signals in cancer and Alzheimer’s disease networks. The availability of functional profiling data (such as biochemical target selectivity information or efficacy readouts) for numerous small molecule compounds has enabled building interaction network models to predict cancer addictions i.e. genes that are essential for disease progression but are not necessarily mutated. In this work, network-based computational methods (such as kinase inhibition sensitivity score – KISS) were developed to infer disease addictions (either single genes or sub-networks) using functional data from high-throughput drug sensitivity screens, and applied in breast cancer cell lines. Further extension of the KISS method, named combinatorial KISS, was introduced as a novel approach to predict synergistic drug combinations and their underlying co-essential target pairs. Driver deconvolution from drug response profiles relies on extensive and reliable drug-target interaction networks. Therefore, a systematic evaluation of target selectivity profiles was performed among recently published large-scale biochemical assays of kinase inhibitors, combined with data reported in the drug-target databases ChEMBL and STITCH. Our comparative evaluation revealed relative benefits and potential limitations among various bioactivity types, including IC50, Ki, and Kd. To make better use of the complementary information captured by the various bioactivity types, we developed a model-based integration approach, termed KIBA, and demonstrated how it can be used to classify kinase inhibitor targets. As a result, we created kinome-level, quantitative drug–target interaction network for further modeling studies. Besides the analysis of drug responses, another way to find novel disease drivers or molecular vulnerabilities is to explore the interaction partners of known oncogenes, since the existence of a protein-protein interaction suggests their involvement in the same biological pathway and thereby in the same biological process. However, one of the major challenges in the protein-protein interaction screens is the identification of functionally relevant interactions from the long hit list, in particular when their functional annotations are missing. This motivated the development of Relevance Rank Platform (RRP) approach that can suggest the candidate proteins from the high throughput screens that most likely contribute to the function of the bait protein. The method predicts functionally similar candidate interactors regardless of either the reliability of the mass spectrometry-based identification, or the knowledge of the biological function of the putative interactor. RRP was applied and validated in PIN1 (Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1) and PME-1 (Protein Phosphatase Methylesterase 1) interaction networks in prostate cancer. Finally, we carried out functional comparison of nitrosylated proteins in the brain synaptosomes of Alzheimer’s disease (AD) mouse models and their healthy controls, with the aim to reveal the disease processes in which this posttranslational modification plays a role. We also elucidated the amyloid precursor protein (APP) - centered Alzheimer’s disease network of differentially nitrosylated proteins that are likely to be implicated in this neurological disorder. Taken together, this thesis work introduces novel experimental-computational strategies for the deconvolution or prioritization of potential disease drivers, either single proteins or their subnetworks. These methods are applicable to various cell lines or patient-derived samples. They can provide directly druggable therapeutic targets for personalized treatment applications and may be used in the development of novel therapeutic options.
  • Gebraad, Arjen (Helsingin yliopisto, 2018)
    This dissertation describes novel tissue engineering approaches for the treatment of intervertebral disc (IVD) degeneration. Defects in the outer part of the IVD, the so-called annulus fibrosus (AF), cannot be restored using the current surgical methods. AF tissue cannot be regenerated using autologous AF cells, because of their limited availability and expansion capacity. We compared the potency of transforming growth factor-beta (TGF-beta) type 1 and type 3 to stimulate differentiation of adipose tissue derived-mesenchymal stem cells (AT-MSCs) towards an AF-like phenotype. We engineered AF tissue in vitro by seeding and stimulating AT-MSCs inside AF-mimetic polymer scaffolds. Several techniques to seed cells in the scaffolds were compared. Cells release membrane vesicles called extracellular vesicles (EVs). EVs have gained interest as a biomimetic tool to induce lineage-specific differentiation of stem cells. We evaluated gene expression in AT-MSCs after exposure to EVs from activated monocytes or osteoclasts. Neither TGF- beta 1 nor TGF- beta 3 increased matrix synthesis by AT-MSCs. Nevertheless, TGF- beta 3 supported cell proliferation and thereby matrix accumulation. Seeding of AT-MSCs into the scaffolds using fibrin gel resulted in superior cell distribution, proliferation and AF-like matrix production compared to other seeding strategies. The formed collagen was aligned into bundles within the pore channels of the scaffolds. Activated monocytes promoted the chemotaxis of immune cells by AT-MSCs via EV-mediated signalling, showing the importance of EVs in controlling the function of the immune system. Monocyte-derived EVs upregulated the expression of matrix metalloproteinases in AT-MSCs. The results show the potential of AT-MSCs as a multipotent cell source in tissue engineering applications for the treatment of degenerated IVDs. The extracellular matrix deposited in the cell-seeded scaffolds had a composition and structure similar to that in native AF tissue, demonstrating the high potential of this strategy in AF repair. Furthermore, the study sheds light on the mechanism by which EVs regulate the immune system and bone remodelling.
  • Gucciardo, Erika (Helsingin yliopisto, 2018)
    Invasion of the extracellular matrix (ECM) and dissemination via the lymphatic and blood circulation are key events in tumour progression. These events involve biological processes where responses to growth stimuli, cytoskeletal and ECM remodelling are interconnected. Plasticity of cell invasion is used as a way to cope with the tumour microenvironment that is continuously changing as a result of tumour progression. In addition, the accumulating mutation load in progressing tumours provides cell inherent triggers that tweak cell behaviour, including invasion. Thus, cancer cell plasticity and adaptability to environmental challenges confound therapeutic efforts aimed at eradicating metastases and halting tumour spread. Cell invasion is also harnessed by the cellular tumour microenvironment, including cancer-associated fibroblasts (CAFs), endothelial cells (ECs) and macrophages. Lymphatic and blood ECs also utilize the invasion machinery during developmental and physiological angiogenesis as well as in pathological vascular remodelling, like tumour angiogenesis and microvascular complications of diabetes. Understanding the context-dependent mechanisms of cell invasion and plasticity can provide new targets for improved therapies. Invading cancer cells as well as ECs upregulate and use membrane type matrix metalloproteinases (MT-MMPs) for invasion into the ECM. By cooperating with protein kinase signalling and by cleaving cell-surface proteins, MT-MMPs further modify cell behaviour. The purpose of this thesis was to study the tissue microenvironment-dependent molecular networks involved in tumour invasion and pathological vascular remodelling. We found a cooperative signalling mechanism between MT1-MMP and the receptor tyrosine kinase EphA2, whereby MT1-MMP‒dependent cleavage of EphA2 provides breast cancer cells with a mechanism for switching from collective to single-cell invasion. Studies on the MT1-MMP cytosolic tail revealed a new regulatory mechanism for mesenchymal invasion by linking MT1-MMP to the actin-cytoskeleton, through Src-regulated interaction with the cytoskeletal protein palladin. In melanoma, MT3-MMP dependent cleavages of MT1-MMP and of cell surface L1 cell adhesion molecule limited their activities towards pericellular collagen degradation and cell junction disassembly, and blood endothelial transmigration, respectively. These mechanisms supported nodular-type growth and lymphatic vessel invasion of adhesive collagen-surrounded melanoma cell collectives. Pathological angiogenesis also involves the invasion of the ECM as well as interactions with the immediate and soluble microenvironment for efficient neovessel formation. During the work for this thesis we developed an ex vivo culture model for the study of pathological vascular remodelling in the context of relevant interactions between the cellular and acellular tissue microenvironment, by utilizing proliferative diabetic retinopathy patient-derived neovascular tufts and corresponding vitreous fluid. We described that the lymphatic endothelial involvement, also discovered during the work for this thesis, is supported by the ischemia- and inflammation-induced vitreal microenvironment, thus bringing a new concept to the PDR mechanisms and targeting options. The findings of this thesis help us to better understand the molecular mechanisms behind the microenvironment-dependent endothelial and cancer cell behaviour plasticity that critically contributes to disease progression and drug responses in debilitating diseases like cancer and diabetes.
  • Siltari, Aino (Helsingin yliopisto, 2018)
    Cardiovascular diseases and hypertension are common in the aging population. Nutritional life-style factors can help to reduce and maintain a healthy level of blood pressure. Two milk-derived tripeptides, Ile-Pro-Pro and Val-Pro-Pro, have been shown to decrease elevated blood pressure in humans and in experimental models. They also improve endothelial dysfunction and thus promote vascular health. Although their principal blood pressure lowering mechanism is thought to be inhibition of the angiotensin-converting enzyme (ACE), other mechanisms are also possible. ACE is one of the key enzymes in the renin-angiotensin system (RAS) which is linked with bradykinin metabolism. In this thesis, the two tripeptides’ antihypertensive mechanisms were examined using an experimental model of hypertension, spontaneously hypertensive rats (SHR). There was a special focus on bradykinin and its role in vascular reactivity in hypertensive and ageing animals. Furthermore, we evaluated whether the tripeptides possess other mechanism(s) of action in addition to ACE inhibition. We also applied computerized modelling to elucidate the possible role of different cis/trans stereoisomers of the tripeptides in ACE inhibition. Finally, we investigated transport of the tripeptides across cell membrane by modelling this process in caco-2 cells. Long term feeding of the tripeptides retarded the development of hypertension during aging of both SHR and healthy old animals. Bradykinin induced vasorelaxation in young healthy normotensive animals; this was abolished in old animals. However, pre-incubation in vitro with Ile-Pro-Pro before exposure to bradykinin exerted a synergistic effect with bradykinin to induce vasorelaxation even in old animals. Low-grade inflammation in the vasculature has been shown to occur during ageing as well as being present in hypertension. We suggest that this converts the normal bradykinin property to relax blood vessels into a vasoconstrictive effect. Our results show that this phenomenon is related to the production of vasoconstrictive prostanoids in the endothelium. Tripeptides are able to inhibit and activate also other enzymes than ACE at least in in vitro. Our computerized model revealed that cis-trans is the best stereoisomer configuration of the tripeptide to inhibit ACE1. Tripeptides penetrated across the caco-2 cell monolayer in an intact form using both paracellular and peptide transporter 1 (Pept1) mediated routes. The results of the thesis strongly support the concept that the bioactive tripeptides and probably other small molecular peptides from different dietary components such as milk and fish, should be investigated in long-term controlled clinical trials in an elderly population instead of the previously examined young or middle-aged individuals. Special focus should be placed on vascular function which has been a poorly investigated area and has been demonstrated to be improved by the tripeptides, especially in old animals.
  • Helaskoski, Eva (Helsingin yliopisto, 2018)
    The aim of this thesis was to assess the diagnostic procedures of occupational immediate allergic diseases and evaluate the feasibility of skin tests. Occupational contact urticaria was given particular attention. The concomitant occurrence of immediate allergic skin and airway diseases was also investigated. The study was based on a retrospective review of the patient material of the occupational medicine clinic at the Finnish Institute of Occupational Health for the period 1.1.1990–31.5.2011. Positive skin prick tests were noted for organic acid anhydrides, isocyanates, epoxy resins, persulfates, chloramine T, chlorhexidine, and aziridine. Amine hardeners, formaldehyde, glutaraldehyde, paraphenylene-diamine, methacrylates and colophonium all induced sporadic, small prick test reactions with doubtful clinical relevance. Ethanolamines, pyrocatechol, ammonium thioglycolate and glyoxal did not induce any positive prick test reactions during the study period. Of the 291 diagnoses of immediate allergic skin diseases, contact urticaria was diagnosed in 232 cases and protein contact dermatitis in 59 cases. Flour, grains and animal feed were the most common cause, followed by cow dander and natural rubber latex. Exposure to chemicals was the cause of contact urticaria in 14% of the patients. A concomitant airway disease caused by the same work-related agent was diagnosed in 46% of the patients with contact urticaria or protein contact dermatitis. Conclusions: Diagnostics of immediate allergic diseases induced by the occupational environment are challenging and there is a strong need for standardized allergen extracts, established test methods and confirmed guidelines for diagnostics. IgE-mediated sensitization seems to play a significant role in the development of occupational allergic diseases for a selected group of chemicals, and for these chemicals skin prick tests can be of substantial value in the diagnostics. The results should still be interpreted cautiously, and data on exposure, clinical symptoms and results in other clinical tests should be taken into account. For a considerable amount of chemicals, the role of specific IgE in the development of allergic symptoms remains uncertain, and the value of skin prick testing in the diagnostics is limited. Early identification of potential immediate sensitizers in the workplace is important to prevent long-lasting health effects and loss of work ability. Immediate sensitization to chemicals can be prevented by substituting harmful agents, using appropriate working methods and adequate protective equipment, and educating workers. Concurrent allergic airway diseases are quite common in patients with immediate allergic skin diseases, and preventive measures should comprise both skin and airway protection.
  • Parkkinen, Markus (Helsingin yliopisto, 2018)
    Tibia plateau fractures are relatively uncommon, but they are among the most challenging intra-articular fractures to treat. These fractures can lead to early posttraumatic osteoarthritis (OA) and cause disability and constant pain. Currently, the most common treatment is open reduction and stable internal fixation (ORIF), allowing early mobilization of the knee. Tibial plateau fractures can be associated with several concomitant soft tissue injuries of the knee. Historically, the operativetreatment with internal fixation has also been related to an increased risk for serious wound complications. The purpose of this study was to investigate the current management and outcome of proximal tibia fractures. The study population consisted of various groups of patients with proximal tibia fractures treated between 2002 and 2013 at our level I trauma center. The study aimed to determine factors predicting the development of posttraumatic OA following tibial lateral or medial plateau fractures. Another focus was on the incidence of concomitant injuries after the most common lateral plateau fracture type and the need for MRI as a diagnostic tool when treating these fractures. Finally, the predictors for deep surgical site infection after plate fixation of proximal tibia fracture were examined. The results showed that relatively good functional outcome can be predicted after internal fixation of lateral and medial tibial plateau fractures. However, patients with lateral plateau fractures with residual depression of the articular surface >2 mm or valgus deformity >5° had significantly more severe (Kellgren-Lawrence grade 3–4) posttraumatic OA. The most significant predictor of posttraumatic OA after medial plateau fracture was the amount of initial depression of the articular surface measured from the preoperative computer tomography, while the quality of reduction was not found to predict OA. MRI had low sensitivity and specificity in the diagnosis of concomitant injuries in the lateral tibial plateau fracture setting. Also nearly all of the clinically relevant concomitant injuries could be treated through the same lateral arthrotomy at the time of ORIF without the need for additional arthroscopy. There is high morbidity associated with deep SSI in plated proximal tibial fractures. Patient’s age ≥50 years, obesity, history of alcohol abuse, and AO type C fracture are independent risk factors for infection. Performing a fasciotomy also increases the risk of deep infection and should be done with meticulous technique only when deemed necessary.
  • Sipilä, Reetta (Helsingin yliopisto, 2018)
    Breast cancer is the most common cancer among women in the Western world. In Finland, approximately 5000 women are diagnosed with breast cancer each year. Due to advances in treatments, disease prognosis has improved markedly. Pain after breast cancer treatments is a common adverse symptom. The purpose of this prospective study was to identify factors associated with the pain experience in women treated for breast cancer, and to uncover clinically feasible factors associated with acute and persistent pain to develop an easy-to-use screening tool to identify women at the highest risk for persistent pain. The whole cohort included 1000 patients (18-75 years) recruited at the Helsinki University Hospital. Preoperatively, they filled in questionnaires about medical history, overall health, and pain symptoms, depressive symptoms, anxiety, and anger regulation. Experimental pain tests (cold 4°C and heat 48°C) were performed preoperatively. Anesthesia protocol and perioperative pain treatment were recorded. Patients documented pain on the first postoperative week (days 1-7) three times daily in the area of surgery. In the follow-ups (1 month, 6 months, 1, 2, and 3 years) patients completed again the same questionnaires about pain, depressive symptoms, and anxiety. The range of pain sensitivity between women treated for breast cancer was high. Of the women treated for breast cancer 13.5% had developed clinically significant persistent pain at the one-year follow-up. The best predictors of pain of any kind; experimental, acute clinical, or persistent pain, were found to be quite similar. Pain (other chronic pain condition, pain in the area of surgery, or intensity of acute pain), more invasive surgery (axillary clearance), and psychological distress (mainly anxiety) were found to be consistent predictors of heightened pain experience. In addition to these, pain expectation and higher need for oxycodone to achieve satisfactory pain relief after surgery were associated with higher pain intensity during the first postoperative week. Obesity was associated with persistent pain at six months and one year after surgery. The adjuvant treatments added to the risk for persistent pain at one year. Screening tools for preoperative and acute phase use to identify women at risk for persistent pain at six months and at one year after surgery were developed. The one-year prediction tool was validated in two other prospective patient cohorts. The average levels of psychological burden were quite low. However, there was a group of women whose distress remained quite stable during the first year. Anger regulation had only a modest association with pain, and was influenced by age and mood. However, anger inhibition was associated with higher depressive symptoms throughout the three-year follow-up. COMT rs4680 was associated with anger-out.
  • Korhonen, Essi (Helsingin yliopisto, 2017)
    Dengue virus (DENV) serotypes 1-4 are mosquito-borne flaviviruses that are increasingly being diagnosed from travellers returning from subtropical and tropical regions. At present, 50-100 cases of dengue are diagnosed annually in Finland. A mosquito-borne flavivirus, Zika virus (ZIKV), was considered to be a relatively harmless virus found in Africa and Asia with low case numbers and mild disease associations. Since 2013, however, ZIKV has emerged and swept across Polynesia, the Americas and the Caribbean, causing massive outbreaks with new severe complications becoming apparent. Amongst these new complications, neurological symptoms have been observed in adults and, alarmingly, congenital infections resulting in severe developmental disorders, including microcephaly. Due to environmental changes and globalisation, the distribution areas of vectors of DENV and ZIKV have spread towards north, which emphasises the risk of introduction of new MBVs to new areas. This thesis aimed to explore the best possible practices in dengue and Zika diagnostics by studying the available methods of choice, their combinations and different sample materials collected from Finnish traveller patients at different phases of the illness. Additionally, this thesis includes studies exploring the molecular epidemiology of DENV and ZIKV and detailed characterization of a congenital ZIKV infection patient case. The detection kinetics of DENV NS1 antigen and RNA was explored from serum, urine and saliva samples. It was observed that NS1 antigen was detectable from the sera of travellers for notably longer periods than reported for populations living in endemic areas. Urine and saliva were demonstrated to be potential sample materials for DENV diagnostics. Urine, in particular, provides new opportunities for molecular diagnostics of DENV as the time window for detection of viral RNA is notably later during the infection when compared to serum samples. It was observed that also ZIKV RNA detection was successful from urine whereas the serum sample taken at the same time point remained negative. Nowadays, urine is considered to be a suitable sample material in diagnostics. By studying traveller patients, the DENV strain responsible for the Madeiran outbreak in 2012 was identified as DENV-1, most likely of South American origin. The characterization of a virus from a Finnish traveller revealed the circulation of ZIKV in the Maldives for the first time. This case was followed by a few additional traveller cases identified elsewhere. Subsequently, the local authorities conducted surveillance studies and confirmed local transmission of ZIKV by detecting the virus from local mosquitoes. Study in this thesis was among the first reports to provide concrete evidence for the causality between ZIKV infection in a pregnant woman and malformations of central nervous system in the foetus. In this study the virus was isolated from the brain tissue of the foetus. The mother’s viremia was noticed to be prolonged, an observation that later studies have confirmed to be a common phenomenon. Mother’s viremia was detectable weeks before the abnormalities in brain development were visible. The evidence provided by the studies herein, along with other recently published data, have shown that there is a need to update the diagnostic guidelines.
  • Gautam, Prson (Helsingin yliopisto, 2017)
    Triple negative breast cancer (TNBC) is a highly aggressive type of breast cancer that accounts for 15-20% of breast cancer cases. Targeted therapy remains to be established for TNBC that lacks estrogen receptors, progesterone receptors and human epidermal growth factor receptor HER2. This limits the therapy to traditional chemotherapy, radiation and surgery, which is only beneficial to a fraction of TNBC patients. Transcriptomics-based subtyping of TNBC into six classes, but it is unclear how the transcriptomics-based subtypes link to effective therapeutic strategies, resulting in a poor clinical prognosis in comparison to other breast cancer subtypes. Hence, there is an imminent need for identifying molecular markers and druggable targets against TNBC. This study is focused on the establishment of functional profiling of TNBC cell lines based on their drug vulnerabilities, and to identify novel druggable signaling nodes. We studied a panel of 16 TNBC cell lines using a functional profiling approach in which we measured the responses of TNBC cells to 304 oncology compounds and 355 GSK published kinase inhibitors. The clustering analysis based on overall drug-responses did not match the transcriptomics-based subtypes, suggesting the presence of extensive heterogeneity in TNBC and that the genomic or transcriptomic profiles do not always reflect the functional behavior of these cells. First, to go beyond standard anti-proliferative drug effects, we established a multiplexed readout for both cell viability and cytotoxicity. We identified many drug classes (such as anti-mitotics, anti-metabolites), which generally are assumed to have cytotoxic effects, mostly exhibited strong effects on cell viability but failed to kill the cells. However, in a subset of the cell lines, they induced a selective cell death. In those cases, we identified differential levels of protein markers linked to the cytotoxic responses (e.g. high level PAI-1 linked to anti-mitotics), suggesting their potential use in clinics for therapeutic decision. These results highlighted that simple multiplexed cell viability and cytotoxicity measurements provide more insight in cellular responses towards the treatment and thereby may help in providing better translationally predictive readouts. Second, we devised a novel drug response metric, called normalized drug response (NDR), which accounts for many kinds of screening artifacts such as signal growth rate differences in positive and negative control, as well as in drug-treated conditions. We found that the NDR metric is a time-independent method and it significantly improved the drug response curve fitting. Our NDR will be of great value in cell-based high throughput drug screening approaches as it cuts down the cost and time for the replicate experiments and further validation with cytotoxicity assay. Lastly, we used computational approach to decipher the kinase signal addiction of breast cancer cell lines by integrating vulnerabilities to kinase inhibitors and their polypharmacology data. We developed the kinase inhibition sensitivity score (KISS) to predict single and combinatorial signal addictions. For this study, we used 40 kinase inhibitors with well-defined target selectivities. With this approach, we predicted and validated novel synergistic inhibitor combinations against TNBC cells, such as dasatinib with axitinib, bosutinib with foretinib combinations for HCC1937 cells. This study suggests that drug sensitivity profiling is a powerful strategy for de-convolving cancer cell specific target addictions.
  • Lallukka, Susanna (Helsingin yliopisto, 2018)
    Non-alcoholic fatty liver disease (NAFLD) may result from obesity accompanied by insulin resistance and adipose tissue inflammation or from the common genetic variants in PNPLA3 (rs738409, C>G/I148M), TM6SF2 (rs58542926, C>T/E167K) and MBOAT7 (rs641738, C>T). These variants increase the liver fat content and the severity of NAFLD without features of insulin resistance. This thesis aimed to determine the following: i) whether NAFLD predicts type 2 diabetes independent of obesity and other known risk factors; ii) whether adipose tissue is inflamed in subjects homozygous for the PNPLA3 I148M variant; iii) whether obesity and insulin resistance rather than liver fat content increase coagulation factor activities and expression; and iv) which factors predict NAFLD and liver stiffness during an 11-year follow-up period. The present thesis includes one systematic review, two cross-sectional studies and one longitudinal study. Study subjects comprised Finnish adult men and women. Liver fat content was measured by proton magnetic resonance spectroscopy (studies II–IV). The gene expression of inflammatory markers in adipose tissue and that of coagulation factors in the liver were measured using qPCR (studies II and III). We conducted a systematic review of prospective longitudinal studies to determine if NAFLD predicts type 2 diabetes for aim i). Based on these studies ultrasound-diagnosed NAFLD and liver enzymes predict type 2 diabetes independent of confounders such as age and obesity. We found no studies indicating that NAFLD associated with genetic risk variants predicting future risk of type 2 diabetes. A group of 82 subjects were divided into two groups based on body mass index and PNPLA3 genotype for aim ii). The liver fat content was similarly increased in obese/insulin-resistant subjects and in carriers of the I148M variant compared to non-obese subjects and non-carriers of this variant. In obese subjects, the adipose tissue expression of pro-inflammatory chemokine MCP-1 was increased and anti-inflammatory ADIPOQ and TWIST1 were decreased compared with non-obese subjects, while these were comparable between carriers and non-carriers of the I148M variant. In study III, 92 non-diabetic subjects were divided into two groups based on insulin sensitivity (HOMA-IR) and PNPLA3 genotype. Coagulation factor activities (FVIII, FIX, FXIII, fibrinogen and VWF:RCo) were increased, and the prothrombin time and activated partial thromboplastin time were shortened in insulin-resistant subjects when compared to insulin-sensitive subjects; yet, these factors were similar in carriers and non-carriers of the I148M variant. The hepatic gene expression of FVIII, FIX and fibrinogen gamma-chain were higher in insulin-resistant subjects with NAFLD (n=13) compared with equally obese insulin-sensitive subjects without NAFLD (n=13). In study IV, 97 subjects were examined twice over an interval of 11 years. The baseline liver fat content independently predicted NAFLD and an increased liver stiffness (measured using transient elastography) at 11.3 years more accurately than routinely available clinical and biochemical parameters. Conclusions: Obesity, adipose tissue inflammation and insulin resistance rather than excess hepatic fat per se are related to an increased risk of type 2 diabetes and a pro-coagulant plasma profile observed often in NAFLD. However, the liver fat content emerges as more important predictor of advanced liver fibrosis than the associated metabolic abnormalities. These data support the view that NAFLD is heterogeneous disease.
  • Tikka, Anna (Helsingin yliopisto, 2018)
    Johdanto: Väitöstyön tarkoituksena oli tutkia ANGPTL3 puutoksen aiheuttamia muutoksia ihmisessä rasva-aineenvaihdunnan osalta kliinisesti, populaatiotasolla sekä solutasolla. ANGPTL3 proteiinin on osoitettu säätelevän lipoproteiinilipaasin (LPL) toimintaa ja siten osallistuvan maksasta sekä ohutsuolesta syntetisoitujen kolmiarvoisten (triglyseridi, TG) rasvojen poistoon verenkierrosta. ANGPTL3 toiminnan estymiseen vaikuttavat mutaatiot (LOF; loss of function) aiheuttavat familiaaliseen hypolipidemian fenotyypin (FHBL2), jonka pääpiirteenä on matalat veren VLDL, LDL ja HDL lipoproteiinien tasot. Päämenetelmät: Solumalleilla tutkittiin ANGPTL3:n kudosspesifistä toimintamekanismia hiljentämällä ANGPTL3 shRNA-lentivirus vektorilla hepatosyyteissä sekä enterosyyteissä. Tutkittavien lipidien ja proteiinien tasoja mitattiin sekä soluista että solumediasta entsymaattisilla menetelmillä sekä ELISA menetelmillä. Leimattujen substraattien avulla selvitettiin solujen metabolian muutoksia. Geenien ilmentymistä soluissa tutkittiin kvantitatiivisella PCR (qPCR)-analyysillä. Koe-henkilöt, joihin kuului ANGPTL3 LOF kantajia sekä kontrollihenkilöitä nauttivat rasvapitoisen aterian, jonka jälkeen kerätyistä plasmanäytteistä mitattiin lipoproteiinien, rasva-aineenvaihdunnan markkereiden sekä TG:ien, kolesterolin ja fosfolipidien pitoisuuksia. Populaatiotutkimuksessa suomalaisten ANGPTL3 varianttien kantajien lipiditasot määritettiin tarkoituksena selvittää ANGPTL3 varianttien osuutta dyslipidemioissa. Verenkierrossa olevan ANGPTL3-proteiinin konsentraatio mitattiin henkilöiltä, joiden lipidiarvot vastasivat hyper- tai hypolipidemiaa, jonka jälkeen tasoja verrattiin lipidiarvoihin sekä muihin lipidimetabolian biomarkkereihin mahdollisten korrelaatioiden löytämiseksi. Johtopäätökset: Tulosten perusteella ANGPTL3:n ilmentymistä soluissa säätelevät insuliini, PPARy-agonisti rosiglitazone sekä LXR-agonistit. ANGPTL3-hiljennys aiheuttaa VLDL-partikkelien lipidaation laskua hepatosyyteissä insuliini stimuloinnin aikana sekä CD36- ja PLTP-geenien ilmentymistason laskua soluissa. ANGPLT3-LOF kantajien kliinisessä tutkimuksessa havaittiin, että ANGPTL3-puutoksen omaavilla homotsygooteilla LOF kantajilla ei esiintynyt postprandiaalista hyperlipidemiaa, toisin kuin heterotsygooteilla kantajilla ja kontrollihenkilöillä, ja tämän fenotyypin voidaan katsoa olevan ateroskleroosia ehkäisevä tekijä. ANGPTL3 puutos aiheuttaa myös veren rasvahappojen määrän vähenemistä verenkierrossa ja siten mahdollisesti vähentää maksaan päätyvien rasvahappojen määrää ja niiden oksidaatiota. Populaatiotutkimuksessa ANGPTL3-varianttien kantajien osuus oli vähäinen, ja dyslipidemiaa oli havaittavissa yhdellä haitallisen variantin kantajalla. Varianttia ei vähäisen kantajien määrän takia pystytä luotettavasti kausaalisesti yhdistämään fenotyyppien aiheuttajaksi. ANGPTL3:n plasma tasot eivät eronneet hypo- tai hyperlipideemisten henkilöiden välillä, ja täten voidaan todeta, että ANGPTL3:n plasmapitoisuudet eivät toimi hyvänä biomarkkerina ennustettaessa veren lipiditasoja.