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  • Rinta-Valkama, Johanna (Helsingin yliopisto, 2006)
    Type 1 diabetes is a disease where the insulin-producing beta cells of the pancreas are destroyed by an autoimmune mechanism. The incidence of type 1 diabetes, as well as the incidence of the diabetic kidney complication, diabetic nephropathy, are increasing worldwide. Nephrin is a crucial molecule for the filtration function of the kidney. It localises in the podocyte foot processes partially forming the interpodocyte final sieve of the filtration barrier, the slit diaphragm. The expression of nephrin is altered in diabetic nephropathy. Recently, nephrin was found from the beta cells of the pancreas as well, which makes this molecule interesting in the context of type 1 diabetes and especially in diabetic nephropathy. In this thesis work, the expression of other podocyte molecules in the beta cells of the pancreas, in addition to nephrin, were deciphered. It was also hypothesised that patients with type 1 diabetes may develop autoantibodies against novel beta cell molecules comparably to the formation of autoantibodies to GAD, IA-2 and insulin. The possible association of such novel autoantibodies with the pathogenesis of diabetic nephropathy was also assessed. Furthermore, expression of nephrin in lymphoid tissues has been suggested, and this issue was more thoroughly deciphered here. The expression of nephrin in the human lymphoid tissues, and a set of podocyte molecules in the human, mouse and rat pancreas at the gene and protein level were studied by polymerase chain reaction (PCR) -based methods and immunochemical methods. To detect autoantibodies to novel beta cell molecules, specific radioimmunoprecipitation assays were developed. These assays were used to screen a follow-up material of 66 patients with type 1 diabetes and a patient material of 150 diabetic patients with signs of diabetic nephropathy. Nephrin expression was detected in the lymphoid follicle germinal centres, specifically in the follicular dendritic cells. In addition to the previously reported expression of nephrin in the pancreas, expression of the podocyte molecules, densin, filtrin, FAT and alpha-actinin-4 were detected in the beta cells. Circulating antibodies to nephrin, densin and filtrin were discovered in a subset of patients with type 1 diabetes. However, no association of these autoantibodies with the pathogenesis of diabetic nephropathy was detected. In conclusion, the expression of five podocyte molecules in the beta cells of the pancreas suggests some molecular similarities between the two cell types. The novel autoantibodies against shared molecules of the kidney podocytes and the pancreatic beta cells appear to be part of the common autoimmune mechanism in patients with type 1 diabetes. No data suggested that the autoantibodies would be active participants of the kidney injury detected in diabetic nephropathy.
  • Lahdenkari, Anne-Tiina (Helsingin yliopisto, 2005)
  • Rahikainen, Agneta (Helsingin yliopisto, 2014)
    The Poet And Her Apostles A biomythographical analysis of the image of Edith Södergran This dissertation is about the constructions and biographical interpretations of the life of the poet Edith Södergran that have emerged since her death in 1923. I investigate what lies behind the agendas and approaches of biographers and scholars, the sources and authorities on which they base their findings and the sources and authorities they have chosen to ignore, and if so, why. I also explore the ways in which they have interpreted her work and placed it in a literary canon. To support my analysis I have made use of Michael Benton's study Literary Biography. An Introduction (2009). Benton employs the concept of biomythography to signify a biography that reflects the dependence of facts on the manner in which they are produced, as well as on cultural context and change. My biomythographical analysis examines these aspects with reference to the ways in which the various interpretations of Södergran are constructed. As a method I have also used parts of a model from Petra Broomans dissertation Jag vill vara mig själv . Stina Aronson (1892 1956), ett litteraturhistoriskt öde (1999), which she based on Hayden White's theory of narrative linguistic expressions in historical research, as expressed in his book Meta History: The Historical Imagination in Nineteenth-Century Europe (1973). I focus on those aspects of Södergran's life that are relevant to the way in which the myths surrounding her emerged, her linguistic and cultural background, her social contacts, medical history, financial situation, ideological interests, position and attitude in literary politics, and the environments in which she lived. I also describe the contemporary reception of her work and the images that it created. Hagar Olsson and Elmer Diktonius are important actors in the early constructions of Södergran s image. The work of her biographer Gunnar Tideström and the scholar Olof Enckell were to a large extent influenced by Hagar Olsson s interpretation of Södergran as it was later manifested in her edition of the poet s letters (Ediths brev, 1955). In the last chapter before the conclusion I describe how the various images of Södergran appear in reference works of literary history, which of the myths about her have survived and which of them have to this day been downplayed.
  • Björk, Ulrika (Helsingin yliopisto, 2009)
    In the last thirty years, primarily feminist scholars have drawn attention to and re-evaluated the philosophy of Simone de Beauvoir (1908 1986). Her philosophical practice has been described as non-systematic, and her literary writing has been viewed as part of her non-systematic mode of philosophising. This dissertation radically deepens the question concerning Beauvoir s philosophical motivations for turning to literature as a mode to express subjectivity. It explicates the central concepts of Beauvoir s philosophy of existence, which are subjectivity, ambiguity, paradox and temporality, and their background in the modern traditions of existential philosophy and phenomenology. It also clarifies Beauvoir s main reason to turn to literature in order to express subjectivity as both singular and universal: as a specific mode of communication, literature is able to make the universality of existence manifest in the concrete, singular and temporal texture of life. In addition, the thesis gives examples of how Beauvoir s literary works contribute to an understanding of the complexity of subjectivity. I use the expression poetics of subjectivity to refer to the systematic relation between Beauvoir s existential and phenomenological notion of subjectivity and her literary works, and to her articulations of a creative mode of using language, especially in the novel. The thesis is divided into five chapters, of which the first three investigate Beauvoir s philosophy of existence at the intersection of the modern traditions of thought that began with René Descartes and Søren Kierkegaard s intuitions about subjectivity. Chapter 1 interprets Beauvoir s notion of ambiguity, as compared to paradox, and argues that both determine her notion of existence. Chapters 2 and 3 investigate the phenomenological side of Beauvoir s philosophy through a study of her response to early French interpretations of transcendental subjectivity, especially in the works of Jean-Paul Sartre and Maurice Merleau-Ponty. My analysis shows that Edmund Husserl s distinction between different levels of subjective experience is central to Beauvoir s understanding of subjectivity and to the different ego concepts she uses. Chapter 4 is a study of Beauvoir s reflections on the expression of subjective thought, and, more specifically, her philosophical conceptions of the metaphysical novel and the autobiography as two modes of indirect communication. Chapter 5, finally, compares two modes of investigating concrete subjectivity; Beauvoir s conceptual study of femininity in Le deuxième sexe and her literary expression of subjectivity in the novel L Invitée. My analysis reveals and explicates Beauvoir s original contribution to a comprehensive understanding of the becoming and paradox of human existence: the fundamental insight that these phenomena are sexed, historically as well as imaginatively.
  • Viitamäki, Mikko (Helsingin yliopisto, 2015)
    This study discusses poetic communication in the context of maḥfil-i samāʿ (an assembly of listening to sung poetry) among South Asian Sufis. Drawing from both textual and ethnographic materials, the study explores the relationship between Sufi practice, poetic expression, and musical performance. It presents a context-sensitive reading of a multilingual (Persian, Hindi, Urdu) poetic corpus that takes into account its literary characteristics, the framework of Sufi practice, as well as the various techniques the qawwali musicians utilize in delivering the meaning of a poetic text. The study comprises three parts that are distinguished by their sources and methodological approaches. The first part discusses the dynamics of samāʿ as a meditative and ecstatic Sufi practice, and it is based on close reading of textual sources in Arabic, Persian and Urdu, written between the fourteenth and twentieth centuries. Throughout these texts, the authors have characterized samāʿ as a spiritual practice whose transformative effect is sudden, even violent. The second part examines twentieth-century anthologies of qawwali poetry and shows the extreme fluidity of the poetic repertoires; the performers are fairly free to choose the texts they sing as long as they bring about the desired effect in the listeners. The study of poetry in samāʿ, however, is bound to remain suggestive, if it is solely based on textual sources. Each performance of a poetic text is uniquely shaped in the interaction between the listeners and singers. For this reason, the third part of the study covers an ethnographic analysis of four samāʿ assemblies that took place in Delhi and Hyderabad. While the focus is on the poetic text, the analysis takes into account the physical settings of the occasions, the hierarchies that regulate the interaction of the participants, as well as the economics involved. The analysis reveals how the qawwals intertwine musical and poetic conventions in order to continuously alternate between tension and release during maḥfil-i samāʿ. In this manner, they intensify the listenersʼ feelings and emotions which are then ideally integrated into their spiritual practice. The impassioned poetic expression that addresses god as the beloved also constitutes a significant religious discourse that complements the more systematic approach found in Islamic theological and legal prose writings.
  • Nyström, Samu (Helsingin yliopisto, 2013)
    The Wartime Biography of Helsinki 1914 - 1918 The dissertation studies the crises in urban life in Helsinki during the First World War. The study examines how and why the war challenged everyday life and the survival strategies of the city and its citizens. The theoretical bases of this study are Amartya Sen s theory on the standard of living and Juha Siltala s writings about the aspiration to equality during times of crises. The impacts of World War I are examined in a wider European urban context. In this study I demonstrate how the fate of the urban community of Helsinki was in many ways similar to most other European urban communities during World War I. The basic structures of urban life were threatened and people had to cope with food and energy shortages, housing problems, increasing costs of living and security problems. In Finland, Russia and Germany the governments and city administrations could not fulfill the demands created by the equal share of sacrifice in the big cities. Black markets and profiteers became necessary parts of everyday life. The February Revolution of 1917 threw the entire Russian Empire into a period of struggle for power. The streets of the cities of the Empire were full of angry city-dwellers who were tired of worsening standards of living and an unequal share of sacrifice. As a capital city, the streets of Helsinki were not only places of local unrest but also locations for the national struggle for power. The Finnish revolution started in Helsinki at the beginning of 1918, and Helsinki was the capital and heart of the revolution for two and a half months. Urban unrest, streetfights and terror were not limited to the Russian Empire. Similar processes were launched in Germany and other Eastern European countries in the following years. During the time of crises the city of Helsinki and its city-dwellers had to develop their own survival strategies. The city had to organize many kinds of support for the hungry, jobless and poor. At the same time the city had no power or even the will to be the only provider for citizens. Everyone had to learn how to fulfill the needs of everyday life during wartime. People started to establish many kinds of social networks and individual organizations to cope with the worsening problems. No one could survive alone in the big city during the times of crises.
  • Tyynelä, Jani (Helsingin yliopisto, 2011)
    In remote-sensing studies, particles that are comparable to the wavelength exhibit characteristic features in electromagnetic scattering, especially in the degree of linear polarization. These features vary with the physical properties of the particles, such as shape, size, refractive index, and orientation. In the thesis, the direct problem of computing the unknown scattered quantities using the known properties of the particles and the incident radiation is solved at both optical and radar spectral regions in a unique way. The internal electromagnetic fields of wavelength-scale particles are analyzed by using both novel and established methods to show how the internal fields are related to the scattered fields in the far zone. This is achieved by using the tools and methods that were developed specifically to reveal the internal field structure of particles and to study the mechanisms that relate the structure to the scattering characteristics of those particles. It is shown that, for spherical particles, the internal field is a combination of a forward propagating wave with the apparent wavelength determined by the refractive index of the particle, and a standing wave pattern with the apparent wavelength the same as for the incident wave. Due to the surface curvature and dielectric nature of the particle, the incident wave front undergoes a phase shift, and the resulting internal wave is focused mostly at the forward part of the particle similar to an optical lens. This focusing is also seen for irregular particles. It is concluded that, for both spherical and nonspherical particles, the interference at the far field between the partial waves that originate from these concentrated areas in the particle interior, is responsible for the specific polarization features that are common for wavelength-scale particles, such as negative values and local extrema in the degree of linear polarization, asymmetry of the phase function, and enhancement of intensity near the backscattering direction. The papers presented in this thesis solve the direct problem for particles with both simple and irregular shapes to demonstrate that these interference mechanisms are common for all dielectric wavelength-scale particles. Furthermore, it is shown that these mechanisms can be applied to both regolith particles in the optical wavelengths and hydrometeors at microwave frequencies. An advantage from this kind of study is that it does not matter whether the observation is active (e.g., polarimetric radar) or passive (e.g., optical telescope). In both cases, the internal field is computed for two mutually perpendicular incident polarizations, so that the polarization characteristics can then be analyzed according to the relation between these fields and the scattered far field.
  • Hietala, Eeva-Maija (Helsingin yliopisto, 2004)
  • Niskanen, Jukka (Helsingin yliopisto, 2013)
    Binding of a flexible polymer chain to a solid surface or air-water interface affects its conformational freedom. A polymer covalently grafted to a surface can adopt three dimensional conformations, limited however by interactions with the surface and the neighboring chains. A dense grafting of polymers forces the polymers to adopt more elongated conformations than what they would take in solutions or amorphous solid state. On the other hand, strong interactions between the polymer and the surface cause the polymer to adsorb to the surface. The air-water interface is a two dimensional space. Also in this space, polymers are more elongated than in solutions. Certain polymers that are insoluble in water can form monolayers at the air-water interface. Water soluble polymers can be anchored to the surface with hydrophobic moieties, so that the polymers do not dissolve into the bulk of the solution during the deformation of the interface. In this work, controlled radical polymerization techniques have been utilized in the syntheses of polymer grafted gold, silver and clay nanoparticles. Gold nanoparticles were grafted with the well-known thermoresponsive poly(N-isopropyl acrylamide), PNIPAM, and poly(N-isopropyl acrylamide-co-N-propyl acrylamides), P(NIPAM-NPAMs). The particles were either dispersible or non-dispersible in water. Monolayers of the polymers and polymer grafted gold nanoparticles formed on an air-water interface were characterized using a Langmuir trough. Silver nanoparticles grafted with soft acrylate copolymers, poly(butyl acrylate-co-methyl methacrylate) were produced to be used in antimicrobial coatings. A block copolymer with an oligomeric acrylic acid block located at the surface of the silver nanoparticles proved to be an optimal choice. The short hydrophilic block promoted the dissolution of silver ions from the coating and also produced the most homogenous particles. Thermoresponsive properties of poly(dimethylaminoethyl methacrylate), PDMAEMA, are strongly affected by the grafting of the polymer to montmorillonite clay nanoparticles. PDMAEMA is a weak polyelectrolyte and thus the charge of the polymer chains can easily be tuned by altering the pH of the solutions. Increasing the charge of the polymer by lowering the pH of the dispersions, or increasing the relative amount of clay in the hybrid material, had significant effects on the thermo responsive properties of PDMAEMA. Both factors change the polymer-polymer and polymer-clay interactions. Increasing the isotacticity of the thermoresponsive polymers PDMAEMA and PNIPAM affects the phase transition at the lower critical solution temperature. In fact, PNIPAM loses its water solubility when the isotacticity is high enough. The effect of increased isotacticity on the phase transition of PDMAEMA was investigated by micro calorimetry and by measuring the zeta potentials of the polymers. The interfacial properties were looked upon by conducting surface tension and interfacial surface rheological measurements on aqueous solutions of both atactic and isotactic-rich PDMAEMA. The behavior of stereoblock polymers of isotactic-atactic PNIPAM was studied at the air-water interface using interfacial surface rheology. The block sequence and thus the different architectures of the polymeric micelles had a great influence on the interfacial properties.
  • Castro, Pascal (Helsingin yliopisto, 2005)
  • Elo, Pertti (Helsingin yliopisto, 2009)
    The commodity plastics that are used in our everyday lives are based on polyolefin resins and they find wide variety of applications in several areas. Most of the production is carried out in catalyzed low pressure processes. As a consequence polymerization of ethene and α-olefins has been one of the focus areas for catalyst research both in industry and academia. Enormous amount of effort have been dedicated to fine tune the processes and to obtain better control of the polymerization and to produce tailored polymer structures The literature review of the thesis concentrates on the use of Group IV metal complexes as catalysts for polymerization of ethene and branched α-olefins. More precisely the review is focused on the use of complexes bearing [O,O] and [O,N] type ligands which have gained considerable interest. Effects of the ligand framework as well as mechanical and fluxional behaviour of the complexes are discussed. The experimental part consists mainly of development of new Group IV metal complexes bearing [O,O] and [O,N] ligands and their use as catalysts precursors in ethene polymerization. Part of the experimental work deals with usage of high-throughput techniques in tailoring properties of new polymer materials which are synthesized using Group IV complexes as catalysts. It is known that the by changing the steric and electronic properties of the ligand framework it is possible to fine tune the catalyst and to gain control over the polymerization reaction. This is why in this thesis the complex structures were designed so that the ligand frameworks could be fairly easily modified. All together 14 complexes were synthesised and used as catalysts in ethene polymerizations. It was found that the ligand framework did have an impact within the studied catalyst families. The activities of the catalysts were affected by the changes in complex structure and also effects on the produced polymers were observed: molecular weights and molecular weight distributions were depended on the used catalyst structure. Some catalysts also produced bi- or multi-modal polymers. During last decade high-throughput techniques developed in pharmaceutical industries have been adopted into polyolefin research in order to speed-up and optimize the catalyst candidates. These methods can now be regarded as established method suitable for both academia and industry alike. These high-throughput techniques were used in tailoring poly(4-methyl-1-pentene) polymers which were synthesized using Group IV metal complexes as catalysts. This work done in this thesis represents the first successful example where the high-throughput synthesis techniques are combined with high-throughput mechanical testing techniques to speed-up the discovery process for new polymer materials.
  • Shan, Jun (Helsingin yliopisto, 2006)
    Polymer protected gold nanoparticles have successfully been synthesized by both "grafting-from" and "grafting-to" techniques. The synthesis methods of the gold particles were systematically studied. Two chemically different homopolymers were used to protect gold particles: thermo-responsive poly(N-isopropylacrylamide), PNIPAM, and polystyrene, PS. Both polymers were synthesized by using a controlled/living radical polymerization process, reversible addition-fragmentation chain transfer (RAFT) polymerization, to obtain monodisperse polymers of various molar masses and carrying dithiobenzoate end groups. Hence, particles protected either with PNIPAM, PNIPAM-AuNPs, or with a mixture of two polymers, PNIPAM/PS-AuNPs (i.e., amphiphilic gold nanoparticles), were prepared. The particles contain monodisperse polymer shells, though the cores are somewhat polydisperse. Aqueous PNIPAM-AuNPs prepared using a "grafting-from" technique, show thermo-responsive properties derived from the tethered PNIPAM chains. For PNIPAM-AuNPs prepared using a "grafting-to" technique, two-phase transitions of PNIPAM were observed in the microcalorimetric studies of the aqueous solutions. The first transition with a sharp and narrow endothermic peak occurs at lower temperature, and the second one with a broader peak at higher temperature. In the first transition PNIPAM segments show much higher cooperativity than in the second one. The observations are tentatively rationalized by assuming that the PNIPAM brush can be subdivided into two zones, an inner and an outer one. In the inner zone, the PNIPAM segments are close to the gold surface, densely packed, less hydrated, and undergo the first transition. In the outer zone, on the other hand, the PNIPAM segments are looser and more hydrated, adopt a restricted random coil conformation, and show a phase transition, which is dependent on both particle concentration and the chemical nature of the end groups of the PNIPAM chains. Monolayers of the amphiphilic gold nanoparticles at the air-water interface show several characteristic regions upon compression in a Langmuir trough at room temperature. These can be attributed to the polymer conformational transitions from a pancake to a brush. Also, the compression isotherms show temperature dependence due to the thermo-responsive properties of the tethered PNIPAM chains. The films were successfully deposited on substrates by Langmuir-Blodgett technique. The sessile drop contact angle measurements conducted on both sides of the monolayer deposited at room temperature reveal two slightly different contact angles, that may indicate phase separation between the tethered PNIPAM and PS chains on the gold core. The optical properties of amphiphilic gold nanoparticles were studied both in situ at the air-water interface and on the deposited films. The in situ SPR band of the monolayer shows a blue shift with compression, while a red shift with the deposition cycle occurs in the deposited films. The blue shift is compression-induced and closely related to the conformational change of the tethered PNIPAM chains, which may cause a decrease in the polarity of the local environment of the gold cores. The red shift in the deposited films is due to a weak interparticle coupling between adjacent particles. Temperature effects on the SPR band in both cases were also investigated. In the in situ case, at a constant surface pressure, an increase in temperature leads to a red shift in the SPR, likely due to the shrinking of the tethered PNIPAM chains, as well as to a slight decrease of the distance between the adjacent particles resulting in an increase in the interparticle coupling. However, in the case of the deposited films, the SPR band red-shifts with the deposition cycles more at a high temperature than at a low temperature. This is because the compressibility of the polymer coated gold nanoparticles at a high temperature leads to a smaller interparticle distance, resulting in an increase of the interparticle coupling in the deposited multilayers.
  • Sillanpää, Pia (Helsingin yliopisto, 2007)
    Various endogenous and exogenous factors have been reported to increase the risk of breast cancer. Many of those are related to prolonged lifetime exposure to estrogens. Furthermore, a positive family history of breast cancer and certain benign breast diseases are known to increase the risk of breast cancer. The role of lifestyle factors, such as use of alcohol and smoking has been an area of intensive study. Alcohol has been found to increase the risk of breast cancer, whereas the role of smoking has remained obscure. A multitude of enzymes are involved in the metabolism of estrogens and xenobiotics including the carcinogens found in tobacco smoke. Many of the metabolic enzymes exhibit genetic polymorphisms that can lead to inter-individual differences in their abilities to modify hazardous substrates. Therefore, in presence of a given chemical exposure, one subgroup of women may be more susceptible to breast carcinogenesis, since they carry unfavourable forms of the polymorphic genes involved in the metabolism of the chemical. In this work, polymorphic genes encoding for cytochrome P450 (CYP) 1A1 and 1B1, N-acetyl transferase 2 (NAT2), sulfotransferase 1A1 (SULT1A1), manganese superoxide dismutase (MnSOD) and vitamin D receptor (VDR) were investigated in relation to breast cancer susceptibility in a Finnish population. CYP1A1, CYP1B1 and SULT1A1 are involved in the metabolism of both estrogens and xenobiotics, whereas NAT2 is involved only in the latter. MnSOD is an antioxidant enzyme protecting cells from oxidative damage. VDR, in turn, mediates the effects of the active form of vitamin D (1,25(OH)2D3, calcitriol) on maintenance of calcium homeostasis and it has anti-proliferative effects in many cancer cells. A 1.3-fold (95% CIs 1.01-1.73) increased risk of breast cancer was seen among women who carried the NAT2 slow acetylator genotype and a 1.5-fold (95% CI 1.1-2.0) risk was found in women with a MnSOD variant A allele containing genotypes compared to women with the NAT2 rapid acetylator genotype or to those with the MnSOD VV genotype, respectively. Instead, women with the VDR a allele containing genotypes were found to be at a decreased risk for breast cancer (OR 0.73; 95% CI 0.54-0.98) compared to women with the AA genotype. No significant overall associations were found between SULT1A1 or CYP genotypes and breast cancer risk, whereas a combination of the CYP1B1 432Val allele containing genotypes with the NAT2 slow acetylator genotypes posed a 1.5-fold (95% CI 1.03-2.24) increased risk. Moreover, NAT2 slow acetylator genotype was found to be confined to women with an advanced stage of breast cancer (stages III and IV). Further evidence for the association of xenobiotic metabolising genes with breast cancer risk was found when active smoking was taken into account. Women who smoked less than 10 cigarettes/day and carried at least one CYP1B1 432Val variant allele, were at 3.1-fold (95% CI 1.32-7.12) risk of breast cancer compared to women who smoked the same amount but did not carry the variant allele. Furthermore, the risk was significantly increased with increasing number of the CYP1B1 432Val alleles (p for trend 0.005). In addition, women who smoked less than 5 pack-years and carried the NAT2 slow acetylator genotype were at a 2.6-fold (95% CI 1.01-6.48) increased risk of breast cancer compared to women who smoked the same amount but carried the NAT2 rapid acetylator genotype. Furthermore, the combination of the CYP1B1 432Val allele and the NAT2 slow acetylator genotype increased the risk of breast cancer by 2.5-fold (95% CI 1.11-5.45) among ever smokers. Instead, the MnSOD A allele was found to be a risk factor among postmenopausal long-term smokers (>15 years of smoking) (OR 5.1; 95% CI 1.4-18.4) or among postmenopausal women who had smoked more than 10 cigarettes/day (OR 5.5; 95% CI 1.3-23.4) compared to women who had similar smoking habits but carried the MnSOD V/V genotype. Similarly, within subgroups of postmenopausal women who were using oral contraceptives, hormone replacement therapy or alcohol, women carrying the MnSOD A allele genotypes seemed to be at increased risk of breast cancer compared to women with the MnSOD V/V genotype. A positive family history of breast cancer and high parity were shown to be inversely associated with breast cancer risk among women carrying the VDR ApaI a allele or among premenopausal women carrying the SULT1A1*2 allele, respectively.
  • Koort, Joanna (Helsingin yliopisto, 2006)
    Systematiikka on tieteenala, joka tutkii eliöiden, esimerkiksi bakteereiden, sukulaisuussuhteita, määrittelyä ja luokittelua. Taksonomian voidaan ajatella olevan tämän tieteenalan käytännön sovellus: taksonomian tavoitteena on jakaa eliöt niiden sukulaisuussuhteita kuvaaviin, järkeviin ryhmiin, antaa jokaiselle ryhmälle sitä kuvaava nimi sekä löytää ne ryhmän ominaispiirteet, joiden avulla kyseinen ryhmä voidaan jatkossakin vaikeuksitta tunnistaa uudelleen. Taksonomia siis tarjoaa tutkijoille yhteisen kielen, jotta kaikki puhuisivat asioista niiden "oikeilla nimillä" ja vältyttäisiin väärinkäsityksiltä. Taksonomisten joukkojen perusyksikkö on laji. Suvullisesti lisääntyvillä eliöillä voidaan ajatella, että samaan lajiin kuuluvat ne eliöt, jotka pystyisivät keskenään tuottamaan lisääntymiskykyisiä jälkeläisiä. Asia tosin ei läheskään aina ole näin yksinkertainen. Suvullisen lisääntymisen puuttuessa bakteereiden perhesuhteita on vieläkin vaikeampi määritellä, ja siksi tiedon lisääntyessä aiempaan luokitukseen tulee jatkuvasti muutoksia. Jotta luokittelusta saataisiin mahdollisimman pysyvä ja pitkäkestoinen, on bakteereiden luokittelussa ryhdytty käyttämään niin sanottua polyfaasista (monivaiheista) taksonomiaa, menetelmää, jossa bakteerijoukon ominaisuuksia tutkitaan mahdollisimman monella tavalla ja lopuksi yhdistetään kaikki saatu tieto. Tässä tutkimuksessa polyfaasista taksonomiaa käytettiin hyväksi viiden broilerinlihavalmistesiin liittyvän maitohappobakteeriryhmän tunnistuksessa. Samalla arvioitiin polyfaasisen taksonomian soveltuvuutta maitohappobakteereiden luokittelussa. Tutkimuksessa käytettiin sekä fenotyyppisä (ilmiasuun perustuvia), genotyyppisiä (perimään perustuvia) että fylogeneettisiä (kehityshistoriaan eli evoluutioon perustuvia) menetelmiä. Lopuksi kunkin bakteeriryhmän tulokset koottiin yhteen. Useissa aiemmissa tutkimuksissa oli saatu viitteitä siitä, että Lactobacillus curvatus ja Lactobacillus sakei -lajien taksonomiassa on epäselvyyttä. Tämän tutkimuksen tulosten perusteella luokittelua korjattiin siirtämällä Lactobacillus curvatus- bakteerin melibiosus- alalaji osaksi Lactobacillus sakei- lajia, sen alalajiin carnosus. Polyfaasista lähestymistapaa sovellettiin myös neljän tuntemattoman bakteeriryhmän tunnistamisessa. Tulosten perusteella havaittiin että kaksi näistä, kokkimainen koiran nielurisoista ja suojakaasupakatusta broilerista eristetty ryhmä ja sauvamainen, pääosin pilaantuneesta, marinoimattomasta, suojakaasupakatusta broilerinlihavalmisteesta eristetty ryhmä, oli aiemmin kuvaamattomia lajeja. Molemmat uudet lajit kuvattiin, eli niille annettiin nimet ja niiden ominaisuudet listattiin. Kokkibakteeri sai nimekseen Enterococcus hermanniensis, eläinlääketieteellisen tiedekunnan Helsingin Hermannin kaupunginosassa sijainneen vanhan kampuksen mukaan, ja sauvabakteeri Lactobacillus oligofermentans, sen energiankäytön mukaan (bakteeri pystyy käyttämään eli fermentoimaan vain harvoja = oligo sokereita). Kaksi muuta ryhmää sen sijaan tunnistettiin jo olemassa oleviksi lajeiksi. Kokkimainen bakteeri, joka oli eristetty suojakaasupakatusta, marinoidusta ja marinoimattomasta broilerin koipireisivalmisteesta ja broilerinlihanleikkaamon ilmasta tunnistettiin Streptococcus parauberis- bakteeriksi. Osalla näistä bakteereista oli kuitenkin kaksi ominaisuutta, joiden perusteella ne erosivat muista samaan lajiin kuuluvista kannoista: ne eivät kyenneet hyödyntämään laktoosia energianlähteenään, ja galaktoosiakin vain huonosti. Poikkeuksellisiksi nämä ominaisuudet tekee se, että tätä lajia on pidetty lähinnä lehmän utaretulehdusta aiheuttavana bakteerina, ja siten olisi ollut odotettavissa että kaikki sen jäsenet pystyisivät käyttämään laktoosia ja galaktoosia, maidon yleisimpiä energianlähteitä. Toinen, sauvamainen, espanjalaisesta, vakuumi- ja suojakaasupakatusta "Morcilla de Burgos" verimakkarasta eristetty ryhmä tunnistettiin Weissella viridescens- bakteeriksi. Polyfaasinen lähestymistapa sopi hyvin näille maitohappobakteereille. Yksittäisten testien perusteella ei kestävää lajimääritystä olisi saatu aikaan. Vaikka fenotyyppisten testien tulokset voivat ollakin kirjavia, ne kuuluvat kuitenkin uuden lajin kuvaukseen uusien genotyyppisten menetelmien rinnalle. Tutkimuksessa havaittiin myös, että erilaisten testien tuloksista luodut kirjastot ovat luotettavia apuvälineitä bakteereiden tunnistuksessa, kunhan niitä päivitetään jatkuvasti.
  • Schigel, Dmitry S (Helsingin yliopisto, 2009)
    This thesis examines assemblages of wood-decaying fungi in Finnish old-growth forests, and patterns of species interactions between fruit bodies of wood-rotting Basidiomycetes and associated Coleoptera. The present work is a summary of four original publications and a manuscript, which are based on empirical observations and deal with the prevalence of polypores in old-growth forests, and fungicolous Coleoptera. The study area consists of eleven old-growth, mostly spruce- and pine-dominated, protected forests rich in dead wood in northern and southeastern Finland. Supplementary data on fungus beetle interactions were collected in southern Finland and the Åland Islands. 11251 observations of fruit bodies from 153 polypore species were made in 789 forest compartments. Almost a half of the polypore species demonstrated a distinct northern or southeastern trend of prevalence. Polypores with a northern prevalence profile were in extreme cases totally absent from the Southeast, although almost uniformly present in the North. These were Onnia leporina, Climacocystis borealis, Antrodiella pallasii, Skeletocutis chrysella, Oligoporus parvus, Skeletocutis lilacina, and Junghuhnia collabens. Species with higher prevalence in the southeastern sites were Bjerkandera adusta, Inonotus radiatus, Trichaptum pargamenum, Antrodia macra, and Phellinus punctatus. 198 (86%) species of Finnish polypores were examined for associated Coleoptera. Adult beetles were collected from polypore basidiocarps in the wild, while their larvae were reared to adulthood in the lab. Spatial and temporal parallels between the properties of polypore fruit body and the species composition of Coleoptera in fungus beetle interactions were discussed. New data on the biology of individual species of fungivorous Coleoptera were collected. 116 species (50% of Finnish polypore mycota) were found to host adults and/or larvae of 179 species from 20 Coleoptera families. Many new fungus beetle interactions were found among the 614 species pairs; these included 491 polypore fruit body adult Coleoptera species co-occurrences, and 122 fruit body larva interrelations. 82 (41%) polypore species were neither visited nor colonized by Coleoptera. The total number of polyporicolous beetles in Finland is expected to reach 300 species.
  • Vàrkonyi, Gergely (Helsingin yliopisto, 2003)