Browsing by Title

Sort by: Order: Results:

Now showing items 1222-1241 of 1560
  • Larivaara, Meri (Helsingin yliopisto, 2012)
    Since the late 1990s Russia has seen rapid social change in terms of population decline and low fertility. The health service system has been reformed. A mandatory health insurance system has been constructed and the development of the private sector has taken place. In the field of reproductive health services attitudes towards maternity care, birth control, and termination of pregnancy have undergone considerable change. At the same time new technologies have become available. Access to reliable contraception has improved and the number of induced abortions has declined, but the use of unreliable birth control methods continues to be common practice. Previous studies have reported that many patients are dissatisfied with the quality of health services in the public sector. ---- Relatively little is known about reproductive health providers' knowledge, attitudes and practices concerning family planning. Information about providers' roles in reproductive health promotion is scarce and scattered. Previous literature points to missed opportunities in reproductive health counselling and low patient involvement in clinical decision-making. The objective of this study was to increase the current understanding of the obstacles that limit the extent and effectiveness of reproductive health counselling in the public sector out-patient services in urban Russia. The specific aims were (1) to describe how the delivery of women's reproductive health services is organised in St Petersburg, (2) to analyse the challenges in women's reproductive health services as perceived by health administrators and practising gynaecologists, (3) to analyse gynaecologists' views and practices concerning preventing, planning, and monitoring pregnancy, and (4) to examine gynaecologists' perceptions of the provider-patient relationship. The data of this study are qualitative, consisting of semi-structured interviews and observations. The data were collected between January and May 2005. The data collection consisted of four parts: (1) semi-structured background interviews with administrative personnel and medical professors (N=9), and managers of women's out-patient clinics (N=9), (2) a pilot study involving observations (N=3) and semi-structured interviews (N=2) at a women's out-patient clinic, (3) observations (N=17) and semi-structured interviews (N=12) at two women's out-patient clinics, and (4) visits and comparison interviews (N=4) at five women's out-patient clinics. The main method of data analysis was content analysis. The women's clinics provided a variety of services ranging from preventative gynaecological check-ups and contraceptive counselling to monitoring of pregnancies and treatment of gynaecological complaints. More than 40 per cent of the patient visits concerned monitoring pregnancy, whereas contraceptive counselling was the primary purpose of the visit in only a small number of cases. Women's clinics suffered from a low level of formal funding, which has resulted in user charges in breach of the mandatory health insurance legislation. The clinics had also developed commercial services to improve their financial situation. Many of the study participants were concerned about equal access to health services and the decline of health promotion. The gynaecologists were well-informed about the latest contraceptive methods and had a positive attitude towards promoting their use. They offered contraceptive counselling to many patients, but the coverage was not 100 per cent among women of reproductive age. The depth of contraceptive counselling varied considerably. In about two-thirds of the observed cases patient involvement was low and counselling was provider-centred, but in approximately a third of the cases patient preferences influenced the clinical decision-making process. Gynaecologists regarded the use of reliable contraception as a means of protecting future fertility and avoiding terminations and as a sign of responsible and morally respectable womanhood. Gynaecologists held a medicalised view of pregnancy planning, promoting gynaecological examinations and diagnostic tests before pregnancy. In practice they emphasised specialist knowledge and risk management in monitoring pregnancy, although they thought their work should ideally combine medical expertise and maternal caretaking. The practising gynaecologists felt that there were many gaps in the provider-patient relationship and that patients did not pay enough attention to reproductive health matters. The gynaecologists expressed patient-centred and holistic ideas about patient work in interviews, but patient involvement was limited during the observed clinical encounters. The gynaecologists emphasised medical authority in interviews, but they also wished for warm and trusting provider-patient relationships. The study results suggest that mandatory health benefit packages should be defined in detail and that reforms are needed to the compensation provided by mandatory health insurance to women's clinics. The results indicate that gynaecologists need continuing education in patient-centred counselling and treatment and in how to involve patients in clinical decision-making. The results point to several implications for future research including the need to broaden models of the provider-patient relationship to incorporate mutual liking and trust in the existing models of patient involvement.
  • Sommarhem, Antti (Helsingin yliopisto, 2007)
    Rituximab, a monoclonal antibody against B-cell specific CD20 antigen, is used for the treatment of non-Hodgkin lymphomas (NHL) and chronic lymphatic leukemia. In combination with chemotherapeutics rituximab has remarkably improved the outcome of NHL patients, but a vast variation in the lengths of remissions remains and the outcome of individual patients is difficult to predict. This thesis has searched for an explanation for this by studying the effector mechanisms of rituximab and by comparing gene expression in lymphoma tissue samples of patients with long- and short-term survival. This work demonstrated that activation of complement (C) system is in vitro more efficient effector mechanism of rituximab than cellular mechanisms or apoptosis. Activation of the C system was also shown in vivo during rituximab treatment. However, intravenously administered rituximab could not enter the cerebrospinal fluid, and neither C activation nor removal of lymphoma cells was observed in central nervous system. In vitro cytotoxicity assays showed that rituximab-induced cell killing could be markedly improved with simultaneous neutralization of the C regulatory proteins CD46 (Membrane cofactor protein), CD55 (Decay-accelerating factor), and CD59 (protectin). In a retrospective study of follicular lymphoma (FL) patients, low lymphoma tissue mRNA expressions of CD59 and CD55 were associated with a good prognosis and in a progressive flow cytometry study high expression of CD20 relative to CD55 was correlated to a longer progression free survival. Gene expression profile analysis revealed that expression of certain often cell cycle, signal transduction or immune response related genes correlate with clinical outcome of FL patients. Emphasizing the role of tumor microenvironment the best differentiating genes Smad1 and EphA1 were demonstrated to be mainly expressed in the non-malignant cells of tumors. In conclusion, this thesis shows that activation of the C system is a clinically important effector mechanism of rituximab and that microenvironment factor in tumors and expression of C regulatory proteins affect markedly the efficacy of immunochemotherapy. This data can be used to identify more accurately the patients for whom immunochemotherapy is given. It may also be beneficial in development of rituximab-containing and other monoclonal antibody therapies against cancer.
  • Palotie, Ulla (Helsingin yliopisto, 2009)
    This study aimed at elucidating real-life aspects of restorative treatment practices. In addition, dentists' views and perceptions of and variation in restorative treatment practices with respect to dentist-related factors were evaluated. Reasons for placement and replacement of restoration, material selection, posterior restoration longevity, and the use of local anesthesia were assessed on two cross-sectional data sets. Data from the Helsinki Public Dental Service (PDS) included details on 3057 restorations performed by dentists (n=134) during routine clinical work in 2001. The other PDS data from Vantaa were based on 205 patient records of young adults containing information on 1969 restorations investigated retrospectively from 1994-1996 backwards; 51 dentists performed the restorations. In addition, dentists’ self-reported use of local anesthesia and estimates of restoration longevity were investigated by means of a nationwide questionnaire sent to 592 general dental practitioners selected by systematic sampling from the membership list of the Finnish Dental Association in 2004. All data sets included some background information on dentists such as gender, year of birth or graduation, and working sector. In PDS in 2001, primary caries was the reason for placement of restoration more often among patients aged under 19 years than among older patients (p<0.001). Among patients over 36 years of age, replacements represented the majority. Regarding dentist-related factors, replacements of restorations were made by younger dentists more frequently than by older dentists (p<0.001). In PDS in 1994-1996, the replacement rate of posterior restorations was greater among female dentists than among male dentists (p=0.01), especially for amalgams (p=0.008). The mean age of replaced posterior restoration among young adults was 8.9 (SD 5.2) years for amalgam and 2.4 (SD 1.4) years for tooth-colored restorations, the actual replacement rate for all existing posterior restorations being 7% in PDS in 1994-1996. Of all restorative materials used, a clear majority (69%) were composites in PDS in 2001. Local anesthesia was used in 48% of cases and more frequently for older patients (55%) than for patients aged under 13 years (35%) (p<0.001). Younger dentists more often used local anesthesia for primary restoration than did the older dentists (p<0.001), especially for primary teeth (p=0.005). Working sector had an impact on dentists’ self-reported use of local anesthesia and estimates of restoration longevity; public sector dentists reported using local anesthesia more frequently than private sector dentists for Class II (p=0.04) and for Class III restorations (p=0.01). Private sector dentists gave longer estimates of posterior composite longevity than public sector dentists (p=0.001). In conclusion, restorative treatment practices seem to vary according to patient age and also dentist-related factors. Replacements of restorations are common for adults. For children, clear underuse of local anesthesia prevails.
  • Saarinen, Kristiina (Helsingin yliopisto, 2000)
  • Forsman, Eva (Helsingin yliopisto, 2007)
    Glaucoma, optic neuropathy with excavation in the optic nerve head and corresponding visual field defect, is one of the leading causes for blindness worldwide. However, visual disability can often be avoided or delayed if the disease is diagnosed at an early stage. Therefore, recognising the risk factors for development and progression of glaucoma may prevent further damage. The purpose of the present study was to evaluate factors associated with visual disability caused by glaucoma and the genetic features of two risk factors, exfoliation syndrome (ES) and a positive family history of glaucoma. The present study material consisted of three study groups 1) deceased glaucoma patients from the Ekenäs practice 2) glaucoma families from the Ekenäs region and 3) population based families with and without exfoliation syndrome from Kökar Island. For the retrospective study, 106 patients with open angle glaucoma (OAG) were identified. At the last visit, 17 patients were visually impaired. Blindness induced by glaucoma was found in one or both eyes in 16 patients and in both eyes in six patients. The cumulative incidence of glaucoma caused blindness for one eye was 6% at 5 years, 9% at 10 years, and 15% at 15 years from initialising the treatment. The factors associated with blindness caused by glaucoma were an advanced stage of glaucoma at diagnosis, fluctuation in intraocular pressure during treatment, the presence of exfoliation syndrome, and poor patient compliance. A cross-sectional population based study performed in 1960-1962 on Kökar Island and the same population was followed until 2002. In total 965 subjects (530 over 50 years) have been examined at least once. The prevalence of exfoliation syndrome (ES) was 18% among subjects older than 50 years. Seventy-five of all 78 ES-positives belonged to the same extended pedigree. According to the segregation and family analysis, exfoliation syndrome seemed to be inherited as an autosomal dominant trait with reduced penetrance. The penetrance was more reduced for males, but the risk for glaucoma was higher in males than in females. To find the gene or genes associated with exfoliation syndrome, a genome wide scan was performed for 64 members (28 ES affected and 36 controls) of the Kökar pedigree. A promising result was found: the highest two-point LOD score of 3.45 (θ=0.04) in chromosome18q12.1-21.33. The presence of mutations in glaucoma genes TIGR/MYOC (myocilin) and OPTN (optineurin) was analysed in eight glaucoma families from the Ekenäs region. An inheritance pattern resembling autosomal dominant mode was detected in all these families. Primary open angle glaucoma or exfoliation glaucoma was found in 35% of 136 family members and 28% were suspected to have glaucoma. No mutations were detected in these families.
  • Hietala, Kustaa (Helsingin yliopisto, 2013)
    Background Diabetic retinopathy is the leading cause of acquired visual disability among people of working age in all industrialised countries. Established risk factors for diabetic retinopathy include the duration of diabetes, glycaemic control, blood pressure and dyslipidaemia. However, these risk factors explain less than half of the risk for diabetic retinopathy. It is, thus, obvious that a large proportion of the risk remains to be explored. Aim The aim of the present study was to investigate potential risk factors that could affect the development of severe forms of retinopathy in type 1 diabetes. Patients and Methods The study patients were drawn from the large FinnDiane (Finnish Diabetic Nephropathy study) database. The FinnDiane study is an observational cohort study which since 1997 has collected comprehensive data on patients with type 1 diabetes at 92 centers throughout Finland with the aim of identifying genetic and environmental risk factors for diabetic complications. The patients retinopathy status were verified from ophthalmic and medical files and fundus photographs when available and graded with the ETDRS-scale. All patients underwent a thorough clinical characterisation of their clinical diabetes status by the attending physician at the participating study centers. Results Proliferative diabetic retinopathy showed significant familial clustering in siblings with type 1 diabetes and the heritability h2 adjusted for conventional risk factors suggested a significant genetic contribution to the risk. The siblings first affected by type 1 diabetes had a lower risk of proliferative retinopathy as compared to the siblings later affected by type 1 diabetes. The risk of both proliferative retinopathy and clinically significant macular edema were modified by the patient s age at onset of type 1 diabetes. The patients with higher age at onset of type 1 diabetes had a lower risk of proliferative retinopathy but conversely, a higher risk of clinically significant macular edema. The HbA1c variability was lower in those patients with higher age at onset of type 1 diabetes and the patients with lower HbA1c variability had a lower cumulative incidence and risk of laser treatment and proliferative retinopathy. Conclusion In addition to the conventional risk factors, such as diabetes duration, glycaemic control and blood pressure, familial factors, age at onset of type 1 diabetes and glycaemic profile may explain a significant proportion of the risk of severe forms of diabetic retinopathy.
  • Yang, Hongyan (Helsingin yliopisto, 2004)
  • Robciuc, Marius Robert (Helsingin yliopisto, 2012)
    Excessive accumulation of triacylglycerols in circulation (hypertriglyceridemia) and/or in adipose tissue (obesity) are major risk factors for type 2 diabetes and cardiovascular diseases, two major morbidities worldwide. This thesis provides insights into the function of angiopoietin-like 3 (Angptl3) and Angptl4 in human triacylglycerol metabolism. Immunological assays have been developed and validated to measure human Angptl3 and Angptl4. Studies performed using several population samples showed that circulating levels of Angptl3 and Angptl4 have no or minor effects on plasma triacylglycerol levels. In the case of Angptl3 only complete absence of the protein in plasma, due to a non-sense mutation, generated dramatic changes not only in triacylglycerols but also in all major plasma lipoproteins and lipids, a phenotype referred to as familial combined hypolipidemia. A role for Angptl4 in human obesity was suggested by the study of monozygotic twins discordant for obesity. Serum Angptl4 and adipose tissue ANGPTL4 mRNA levels are significantly decreased in obese twins as compared with their non-obese co-twins. In vitro experiments using human adipocytes revealed that Angptl4 significantly increases the breakdown of triacylglycerol stores, a mechanism that might explain the observations in human subjects. Data obtained using animal models and human genetics clearly show that Angptl4 inhibits LPL activity and may modulate plasma triacylglycerol levels. Because the circulating levels of Angptl4 apparently do not influence LPL activity and plasma triacylglycerols a question emerged whether Angptl4 can have more subtle roles at tissue level. In this thesis, studies using skeletal muscle cells in culture provided evidence that Angptl4 is part of a negative feedback mechanism that is likely to prevent the overload of cells with triacylglycerols. The data showed that free fatty acids, the products of LPL activity, act through peroxisome proliferator-activated receptor δ/retinoic X receptor to upregulate Angptl4 synthesis coupled to inhibition of LPL activity. Furthermore, Angptl4 appears to be regulated by insulin in a tissue specific manner suggesting a mechanism for insulin-mediated fuel partitioning in the body. Taken together this data establish Angptl3 and Angptl4 as important regulators of triacylglycerol metabolism in humans.
  • Katz, Sissi (Helsingin yliopisto, 2007)
    The repair of corneal wounds requires both epithelial cell adhesion and migration. Basement membrane (BM) and extracellular matrix (ECM) proteins function in these processes via integrin and non-integrin receptors. We have studied the adhesion, spreading and migration of immortalized human corneal epithelial (HCE) cells and their interactions with the laminins (Lms), fibronectins and tenascins produced. Human corneal BM expresses Lms-332 and -511, while Lm-111 was not found in these experiments. HCE cells produced both processed and unprocessed Lm-332, whereas neither Lm-111 nor Lm-511 was produced. Because HCE cells did not produce Lm-511, although it was present in corneal BM, we suggest that Lm-511 is produced by stromal keratocytes. The adhesion of HCE cells to Lms-111, -332 and -511 was studied first by determining the receptor composition of HCE cells and then by using quantitative cell adhesion assays. Immunofluorescence studies revealed the presence of integrin α2, α3, α6, β1 and β4 subunits. Among the non-integrin receptors, Lutheran (Lu) was found on adhering HCE cells. The cells adhered via integrin α3β1 to both purified human Lms-332 and -511 as well as to endogenous Lm-332. However, only integrin β1 subunit functioned in HCE cell adhesion to mouse Lm-111. The adhesion of HCE cells to Lm-511 was also mediated by Lu. Since Lm-511 did not induce Lu into focal adhesions in HCE cells, we suggest that Lm-511 serves as an ECM ligand enabling cell motility. HCE cells produced extradomain-A fibronectin, oncofetal fibronectin and tenascin-C (Tn-C), which are also found during corneal wound healing. Monoclonal antibodies (MAbs) against integrins α5β1 and αvβ6 as well as the arginine-glycine-aspartic acid (RGD) peptide inhibited the adhesion of HCE cells to fibronectin. Although the cells did not adhere to Tn-C, they adhered to the fibronectin/Tn-C coat and were then more efficiently inhibited by the function-blocking MAbs and RGD peptide. During the early adhesion, HCE cells codeposited Lm-332 and the large subunit of tenascin-C (Tn-CL) beneath the cells via the Golgi apparatus and microtubules. Integrin β4 subunit, which is a hemidesmosomal component, did not mediate the early adhesion of HCE cells to Lm-332 or Lm-332/Tn-C. Based on these results, we suggest that the adhesion of HCE cells is initiated by Lm-332 and modulated by Tn-CL, as it has been reported to prevent the assembly of hemidesmosomes. Thereby, Tn-CL functions in the motility of HCE cells during wound healing. The different distribution of processed and unprocessed Lm-332 in adhering, spreading and migrating HCE cells suggests a distinct role for these isoforms. We conclude that the processed Lm-332 functions in cell adhesion, whereas the unprocessed Lm-332 participates in cell spreading and migration.
  • Pirilä, Satu (Helsingin yliopisto, 2014)
    This study was designed to evaluate the association of breastfeeding in infancy with health at adulthood. The focus was on diseases and risk factors with public health importance, such as osteoporosis, cardiovascular diseases (CVD) and body composition, particularly central obesity. The cohort (n=238) was originally collected in 1975 in the Maternity Hospital of Helsinki University Central Hospital. A total of 158 subjects (66 percent) from the original cohort participated the follow-up visit at the age of 32 years at the Children s Hospital, Helsinki University Central Hospital to collect data for the present study. Bone mineral density (BMD) was higher among men who had received breast milk for less than 3 months, but the same finding was not seen in women. One potential explanation for the finding is that the important ingredients for bone accrual calcium, phosphate and protein contents were higher in milk formula and cow s milk dilution than in breast milk. The most important determinants of adult body composition were gender, growth in infancy, current physical activity and maternal body mass index. Duration of breastfeeding was not associated with adult body composition but first year s growth and skin fold thickness at 12 months of age were associated with adult body composition. Therefore, breastfeeding had an indirect impact on adult fat accumulation. Individual risk factors of CVD were evaluated and a Framingham risk score (FRS) was calculated, which predicts the risk of coronary heart disease over a period of 10 years. No linkage was confirmed between the duration of breastfeeding and the individual risk factors of CVD or the FRS. The fourth sub-study focused on the possible association between CVD and bone health. Inverse associations of individual risk factors (glucose, insulin) of CVD with bone status (BMD and bone formation markers) were observed in a crude model, but detailed investigation revealed that this association was due to common confounders (fat mass, physical activity, smoking and alcohol). Correspondingly, BMD was slightly lower among those males who fulfilled the criteria for metabolic syndrome, but again the association disappeared after controlling for common confounders. In summary, breast milk has an indirect and relatively minor effect on adult body composition and no association with the risk factors of CVD. Therefore, the duration of breastfeeding is unlikely to resolve any public health problems. BMD was lower but still within normal range among men with extended duration of breastfeeding than in men with shorter duration of breastfeeding, but more studies are needed to confirm this finding. Regardless of these findings, all mothers are recommended to breastfeeding their infants, if possible. If breast milk is insufficient to ensure steady growth, earlier introduction of age-appropriate complementary foods should be encouraged. This study indicates that more emphasis should be placed on other lifestyle such as healthy diet, adequate physical activity and non-smoking, all of which are beneficial both for bone remodeling and weight management.
  • Böckelman, Camilla (Helsingin yliopisto, 2012)
    Worldwide and notably in the developed countries, cancer is an increasing cause of morbidity and mortality, being the second most common cause of death after ischemic heart disease. Now and in the future new cancer cases need to be diagnosed earlier. Prognostic factors may be helpful in recognizing and handling those patients who need more aggressive therapy, and it is also desirable to predict treatment response accurately. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein predominantly expressed in malignant tissues and inhibiting protein phosphatase 2A (PP2A) activity; it is a promising target for cancer therapy. The aim of this thesis was to evaluate the prognostic role of CIP2A in solid cancers, and for this purpose to explore expression of CIP2A, and investigating regulation of CIP2A in order to gain insight into signalling pathways leading to alteration in prognosis. Patients diagnosed with gastric, serous ovarian, tongue, or colorectal cancer at Helsinki University Central Hospital were included. Tumour tissue microarrays assembled from specimens from these patients were prepared and stained immunohistochemically for CIP2A protein expression. Associations with clinicopathologic parameters and other biomarkers were explored, and survival analyses were done according to the Kaplan-Meier method. Study of the role of CIP2A in intracellular signalling in vitro involved gastric, ovarian, and tongue cancer cell lines. We found CIP2A to be highly expressed in gastric, ovarian, tongue, and colorectal cancer specimens. CIP2A was associated with clinicopathologic parameters characterizing an aggressive disease, namely advanced stage, high grade, p53 immunopositivity, and high proliferation index. CIP2A led to recognition of gastric, ovarian, and tongue cancer patients with poor prognosis, however, with a cancer type-specific cut-off level for prognostic significance. In tongue cancer, it served as an independent prognostic marker. In contrast, in colorectal cancer, CIP2A provided no prognostic value. In cancer cell lines, CIP2A was highly expressed at both protein and mRNA levels, and promoted cell proliferation and anchorage-independent growth. In gastric cancer, we demonstrated with a MYCER construct in mouse embryo fibroblasts that activation of MYC led to increased CIP2A mRNA expression, and hence we suggested that a positive feedback mechanism between CIP2A and MYC may potentiate and prolong the oncogenic activity of these proteins. We demonstrated in ovarian cancer an association between CIP2A and EGFR protein overexpression and EGFR gene amplification. In ovarian and tongue cancer cells we showed that depletion of EGFR downregulates CIP2A expression. In conclusion, high CIP2A expression occurred frequently among patients with aggressive disease. CIP2A may serve as a prognostic marker in gastric, ovarian, and tongue cancer and thus may help in tailoring therapy for cancer patients. The positive feedback mechanism between CIP2A and MYC, as well as the positive regulation of CIP2A by EGFR, are a few signalling pathways regulating and regulated by CIP2A. These and other mechanisms need to be studied further, however. CIP2A is a potential target for therapy, and its potential role as predictive marker and as a tumour marker in serum requires exploration.
  • Filppula, Anne (Helsingin yliopisto, 2014)
    The drug-metabolising enzyme cytochrome P450 (CYP) 2C8 is involved in the elimination of several important drugs. The asthma drug montelukast inhibits CYP2C8 potently in vitro, but does not affect the pharmacokinetics of CYP2C8 substrates in vivo. In turn, the cancer drug imatinib is a CYP2C8 and CYP3A4 substrate in vitro, but CYP3A4 inhibitors have little effect on its concentrations in vivo. This thesis aimed to examine these discrepancies, and to study the role of CYP2C8 in the metabolism of montelukast and imatinib. The work comprised in vitro experiments, physiologically based pharmacokinetic (PBPK) simulations, and two interaction studies with a two-phase, placebo-controlled crossover design in healthy subjects. In vitro, CYP2C8 metabolised montelukast extensively. In the clinical study, the strong CYP2C8 inhibitor gemfibrozil increased the area under the plasma concentration time-curve (AUC) of montelukast by 4.5-fold in healthy subjects, thus suggesting that CYP2C8 contributes to ~80% of its elimination. In vitro, imatinib was mainly metabolised by CYP2C8 and CYP3A4, but imatinib also inhibited CYP3A4 irreversibly. In vivo, gemfibrozil unexpectedly reduced imatinib absorption, while it had no effect on imatinib AUC. However, the AUC of the main metabolite of imatinib decreased by ~50%. PBPK simulations suggested that the findings could be explained by a complex interaction involving simultaneous inhibition of an uptake transporter involved in imatinib absorption and of CYP2C8 by gemfibrozil. Furthermore, the simulations proposed that the elimination of imatinib during steady state relies more on CYP2C8 than on CYP3A4, because of CYP3A4 autoinhibition by imatinib. Inhibition of CYP3A4 by imatinib also suggests that concomitant use of imatinib with CYP3A4 substrates may lead to harmful interactions. The findings of this work explain the previously documented in vitro-in vivo inconsistencies and provide important information for a safe use of these drugs. CYP2C8 inhibitors may increase the effect and adverse reactions of montelukast and imatinib. On the other hand, because montelukast is generally well-tolerated and CYP2C8 seems to play a key role in its elimination, these data suggest that it could serve as a CYP2C8 probe in interaction studies. Collectively, the studies of this work strengthen the role of CYP2C8 as an important drug-metabolising enzyme.
  • Pulkkinen, Mari-Anne (Helsingin yliopisto, 2003)
  • Planken, Anu (Helsingin yliopisto, 2012)
    Parkinson´s Disease (PD) is a neurodegenerative movement disorder resulting from loss of dopaminergic (DA) neurons in substantia nigra (SN). Possible causative treatment strategies for PD include neurotrophic factors, which protect and in some cases restore the function of dopaminergic neurons. Glial cell line-derived neurotrophic factor (GDNF) family of neurotrophic factors have been to date the most promising candidates for treatment of PD, demonstrating both neuroprotective and neurorestorative properties. We have investigated the role of GDNF in the rodent dopaminergic system and its possible crosstalk with other growth factors. We characterized the GDNF-induced gene expression changes by DNA microarray analysis in different neuronal systems, including in vitro cultured Neuro2A cells treated with GDNF, as well as midbrains from GDNF heterozygous (Hz) knockout mice. These microarray experiments, resulted in the identification of GDNF-induced genes, which were also confirmed by other methods. Further analysis of the dopaminergic system of GDNF Hz mice demonstrated about 40% reduction in GDNF levels, revealed increased intracellular dopamine concentrations and FosB/DeltaFosB expression in striatal areas. These animals did not show any significant changes in behavioural analysis of acute and repeated cocaine administration on locomotor activity, nor did they exhibit any changes in dopamine output following treatment with acute cocaine. We further analysed the significance of GDNF receptor RET signalling in dopaminergic system of MEN2B knock-in animals with constitutively active Ret. The MEN2B animals showed a robust increase in extracellular dopamine and its metabolite levels in striatum, increased tyrosine hydroxylase (TH) and dopamine transporter (DAT) protein levels by immunohistochemical staining and Western blotting, as well as increased Th mRNA levels in SN. MEN2B mice had increased number of DA neurons in SN by about 25% and they also exhibited increased sensitivity to the stimulatory effects of cocaine. We also developed a semi-throughput in vitro micro-island assay for the quantification of neuronal survival and TH levels by computer-assisted methodology from limited amounts of tissue. This assay can be applied for the initial screening for dopaminotrophic molecules, as well as chemical drug library screening. It is applicable to any neuronal system for the screening of neurotrophic molecules. Since our microarray experiments revealed possible GDNF-VEGF-C crosstalk we further concentrated on studying the neurotrophic effects of VEGF-C. We showed that VEGF-C acts as a neurotrophic molecule for the DA neurons both in vitro and in vivo, however without additive effect when used together with GDNF. The neuroprotective effect for VEGF-C in vivo in rat 6-OHDA model of PD was demonstrated. The possible signalling mechanisms of VEGF-C in the nervous system were investigated - infusion of VEGF-C to rat brain induced ERK activation, however no direct activation of RET signalling in vitro was found. VEGF-C treatment of rat striatum lead to up-regulation of VEGFR-1-3, indicating that VEGF-C can regulate the expression level of its own receptor. VEGF-C dopaminotrophic activity in vivo was further supported by increased vascular tissue in the neuroprotection experiments.
  • Haapasalo-Tuomainen, Karita (Helsingin yliopisto, 2012)
    The key player in human innate immune response is the complement system that attacks microbes and foreign particles invading human body. Complement cascade can be activated through three pathways, the classical, alternative, and lectin pathways. The classical and lectin pathways are activated by recognition of nonself structures while the alternative pathway is constantly in a slightly active stage and is triggered on surfaces that are missing self signals. Surface-deposited complement components act as opsonins for phagocytes while chemotactic and anaphylatoxic components released upon complement activation induce phagocyte recruitment, phagocytosis and the inflammatory response. The components of the late stage of the activation cascade form lytic transmembrane complexes on the surface of the target. Complement activation is regulated by host surface bound as well as fluid phase molecules that act on several steps during the cascade. Factor H (CFH) is an important fluid phase regulator. It is an elongated protein consisting of 20 domains and a common polymorphism Y402H in CFH is located in the domain seven. The same domain interacts with the surface exposed M protein of the pathogenic bacterium, Streptococcus pyogenes, and thereby inhibits the function of the complement system on the microbial surface. The aims of this thesis were to analyze the effects of CFH binding on microbial complement evasion in vivo and in vitro and to analyze how genetic variation in CFH affects S. pyogenes survival and host infection susceptibility. It was shown that Loa loa microfilariae isolated from patient blood carried host CFH and C4BP on themselves. The complement components deposited on microfilariae surface in vivo and in vitro were inactive indicating that the microfilariae evade complement attack using surface bound CFH and C4BP.Most of the S. pyogenes strains studied were found to bind CFH and a recombinant CFH fragment consisting of domains 5-7 (CFH5-7) in vitro. Binding of CFH and CFH5-7 to 38 studied S. pyogenes strains was variable and the binding affinity showed significant inverse relationship with formation of complement activation markers in serum. When a CFH5-7 fragment lacking the cofactor active domains was incubated with the CFH binding strains in an in vitro survival model the multiplication of the bacteria was significantly decreased showing that CFH binding via the domain seven is crucial for survival of S. pyogenes. CFH was isolated from human plasma obtained from donors that were genotyped homozygous for the Y402H polymorphism. The two allotypes bound differentially to the surface of the studied S. pyogenes strains and the diminished binding of the allotype CFH(402H) resulted in a significant decrease in multiplication of the bacteria in an in vitro survival assay. On the basis of these results it seems that the residue 402Y is crucial in S. pyogenes-CFH interaction and that the Y402H polymorphism affects opsonization and phagocytosis of the bacterium. The Y402H (C1277T) genotype was analyzed from patients with history of erysipelas or recurrent tonsillitis (n=487) and from 455 control subjects. Comparison of the allele and genotype frequencies between the patients and control subjects suggests that the polymorphism is associated with susceptibility to streptococcal infections. In conclusion, the results show that complement evasion by binding of complement regulators occurs both in vitro and in vivo and that within the S. pyogenes species CFH binding via the domain seven is a common way to evade complement attack and to enhance microbial survival in the host. It also seems that the CFH Y402H polymorphism affects S. pyogenes survival in vitro and this finding probably also has clinical relevance since the studied polymorphism suggests an association with host susceptibility to streptococcal infections erysipelas and recurrent tonsillitis.