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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

The role of genetic variation in glucokinase and glucokinase regulatory protein in diabetes and related traits

Beer, Nicola L. January 2011 (has links)
The rising prevalence of type 2 diabetes (T2D) is a global problem, and suggests that we need better therapeutic strategies against this disease. The glycolytic enzyme glucokinase (GCK) catalyses the phosphorylation of glucose, and is a well-established T2D drug target. Rare GCK mutations cause monogenic beta-cell dysfunction, whilst common genetic variants within GCK are associated with fasting plasma glucose (FPG) levels and T2D risk. Since GCK is expressed in both the pancreas and liver, pharmacological GCK activation provides the promise of a two-pronged attack on hyperglycaemia. In vivo, GCK activity is modulated by the hepatic inhibitor glucokinase regulatory protein (GKRP, gene GCKR). GKRP negatively regulates GCK activity competitively with respect to glucose, and is controlled by fructose 6- and fructose 1-phosphate (F6P and F1P), which compete with each other for binding and enhance or diminish GCK inhibition respectively. GKRP also sequesters GCK in the nucleus and paradoxically stabilises the enzyme. As GCK and its regulatory protein are fundamental to glucose homeostasis, we aimed to investigate the role of genetic variation in both GCK and GCKR to further our understanding of these important T2D drug targets in a system that would be relevant to man. I demonstrated that two novel GCK mutations (T103S and V389L) identified in patients with hyperinsulinaemic hypoglycaemia were kinetically activating and through structural modelling identified a novel regulatory site for GCK activation by small molecular activators. Genome-wide association studies (GWAS) identified GCKR as a regulator of FPG and triglyceride levels, and showed a role for GKRP in T2D risk. Unlike most GWAS hits, this signal included a non-synonymous variant within GCKR (P446L), thus facilitating functional studies. P446L-GKRP was characterised kinetically and at the cellular sequestration-level. This variant showed diminished F6P-mediated modulation, which was proposed to reduce hepatic GCK inhibition, increase glycolytic flux (decreasing FPG), and feed metabolites into liver pathways (elevating triglycerides). As GCKR was not expressed at functional levels within human islets, this phenotype was thought to be driven by the liver. Preliminary analysis at the cellular level was inconclusive, with optimisation required to study human P446L-GKRP in this cellular system. Finally, I showed that mutations within GCKR are not a common cause of “GCK-Like” phenotypes in man, despite the regulatory protein directly modulating GCK activity. These data provide further insight as to the pathogenic consequences of perturbing GCK activity. This must be considered if this enzyme is to be the subject of therapeutic intervention in T2D.
112

Neuroanatomical screening and analysis of transgenic and ENU induced mutagenised mice

Edwards, Andrew January 2011 (has links)
I have sought to discover genetic causes of neuroanatomical defects by conducting N-ethyl-N-nitrosourea mutagenesis and transgenic knock out screens in mice. The rationale behind this is that mutations causal to structural defects will be informative about developmental neurobiology and the biological basis of behaviour. Direct screening for behavioural abnormalities in mice has historically been arduous and yielded few findings due to small effect sizes and limited statistical power. My approach sought to bypass these problems by screening for highly penetrant morphological phenotypes. This thesis details my screens and the histological, genetic and behavioural characterisation of lines of interest. These include models of hydrocephalous, pyramidal cell layer ectopia, abnormal neurogenesis, corpus callosum agenesis, hippocampal enlargement, elevated cell death and hypomyelination. Whilst N-ethyl-N-nitrosourea mutagenesis screening has been conducted since the twilight of the 20<sup>th</sup> century, systematic transgenic knock out screening is currently in its infancy. By discovering gene-phenotype associations through both approaches, I have been able to compare the relative yields, strengths and weaknesses of the two screening methods. Additionally, I have discussed the significant of the gene-phenotype associations produced from both screens.
113

Acute lung injury : study of pathogenesis and therapeutic interventions

Rocksén, David January 2003 (has links)
No description available.
114

Socioeconomic inequalities in health and disability. : Social epidemiology in the Nord-Trøndelag health study (HUNT), Norway

Krokstad, Steinar January 2004 (has links)
<p>Socioeconomic inequalities in health and disability are found in all countries where social gradients have been studied. Despite rapid economic growth and expanding health care systems, aiming at providing services to people according to need rather than according to wealth, persistent and even widening health inequalities are found in Europe after the second World War.</p><p>In this research project we wanted to establish a method for measuring socioeconomic status based on occupational groups and education in the HUNT Study, thereby providing tools for research in social medicine. A social gradient scale based on the occupational grouping from the HUNT study questionnaires had not been established. When this study was planned however, educational level, which might serve as a proxy for socioeconomic status, had been monitored in both HUNT I and HUNT II.</p><p>Disability pension has been a central element in social security legislation in Norway, established as a universal right for all citizens in 1967. This public income-maintenance program protects workers in case of disability, and comprises both universal and earningrelated programs. The main eligibility criterion has been permanent impaired earning ability by at least 50 % for reasons of illness or disease, injury or disability. Despite objective health improvement in the population the last decades, incidence of disability pension has increased.</p><p>In epidemiology, socioeconomic status is not only an important variable in itself. It is also a confounder that should be taken into consideration in discussing almost all causal relationships. Thus, in population based health studies, measures of socio-economic status are essential. Occupation, education and income together determine the socioeconomic status of a person. However, these factors are sufficiently distinct to require that they should also be studied separately in relation to health. To study them separately is often preferable since this can suggest hypotheses on causal relationships between exposure and disease.</p>
115

CXCL16 and CD137 in Atherosclerosis

Wågsäter, Dick January 2005 (has links)
<p>Atherosclerosis is a progressive inflammatory disease that is characterized by the accumulation of lipids, infiltrated cells and fibrous elements in large arteries.</p><p>This thesis focuses on the molecular mechanisms behind foam cell formation and inflammation, two central processes in the development of atherosclerosis. More specific, we studied the effects of proinflammatory cytokines on CXCL16 expression and its role as scavenger receptor on macrophages and smooth muscle cells in atherogenesis. CXCL16 is defined as a chemokine and a scavenger receptor, regulating adhesion and chemoattraction of CXCR6 expressing cells and uptake of oxLDL. We show that the expression of CXCL16 and its receptor CXCR6 are more pronounced in human atherosclerotic lesions compared with non-atherosclerotic vessels. Increased expression of CXCL16 was also seen in atherosclerotic aortas of apoE-/- mice compared with aortas of non-atherosclerotic, age-matched C57BL/6 mice. In vitro, IFN gamma induced CXCL16 expression in primary human monocytes and smooth muscle cells which resulted in an increased uptake of oxLDL. Treatment of mice with IFN gamma also induced CXCL16 expression in atherosclerotic lesions. Thus, we have demonstrated a role for IFN gamma in foam cell formation through upregulation of CXCL16. The expression of CXCR6 was defined to the same regions as for CXCL16 in the lesion, indicating the presence of cells able to respond to CXCL16. Consequently, CXCL16 could serve as a molecular link between lipid metabolism and immune activity in atherosclerotic lesion.</p><p>CD137 belongs to the TNF family and mediates several important processes in inflammation. CD137 is involved in the activation of T cells, NK cells, B cells and monocytes and regulate cytokine production, proliferation and apoptosis in these cells. A limited number of studies have demonstrated CD137 expression on smooth muscle cells and endothelial cells. Our results show that CD137 mRNA is higher expressed in human atherosclerotic lesions compared with unaffected vessels. We found that endothelial cells express CD137 in atherosclerotic lesions and that cultured endothelial cells and smooth muscle cells express CD137 and CD137 ligand in vitro. CD137 was regulated differentially by proinflammatory cytokines (i.e. IFN gamma, TNF alpha, IL-1 beta) and bacterial lipopolysaccharide depending on cell type. Furthermore, we investigated the effects of CD137 signalling, demonstrating that binding of the CD137 ligand to its receptor increases proliferation and migration of smooth muscle cells.</p><p>In summary, this thesis has focused on the expression, regulation and role of CXCL16 and CD137, two genes that have not been described earlier in the concept of atherosclerosis. The findings demonstrate some of the molecular mechanisms involved in vascular inflammation and may increase our knowledge about the development of atherosclerosis.</p>
116

Nyetablering i den offentliga sjukvården : hinder på två nivåer

Haglund, Anders, Pekkanen, Jukka January 2005 (has links)
<p>Irradia AB tillverkar och säljer terapeutiska, kirurgiska och kosmetiska lasrar. Företaget har hittills inte lyckats skapa utbyte med den offentliga sjukvårdsmarknaden. Syftet med undersökningen var därför att analysera och utvärdera hinder för Irradia AB:s introduktion på den offentliga svenska sjukvårdsmarknaden. Fokus lades på de terapeutiska lasrarna. På grund av undersökningsområdets natur gjordes en separation av mega- och marknadsnivå. På meganivån undersöktes ett expertnätverk, som skall acceptera nya medicinsktekniska produkter inom sitt verksamhetsområde, och på marknadsnivån undersöktes Irradia AB och den offentliga sjukvårdsmarknaden. </p><p>Författarna valde fallstudien som metod. För att samla in primärdata ansåg författarna att intervjuer var den mest relevanta metoden. På marknadsnivån intervjuades Lars Hode, VD för Irradia AB, och Jan Svenonius, tidigare upphandlingschef på Huddinge sjukhus och Mikael Wickström, upphandlingschef, Karolinska Universitetssjukhuset. På meganivån fick Audio Laser-Kliniken representera Irradia, då företagets produkter används till behandling av hörselsjukdomar på kliniken. Med hjälp av ett anvisningsurval lyckades författarna snabbt identifiera och intervjua respondenter som varit kritiska till behandlingsformen som tillämpas på kliniken. </p><p>Analysen på meganivån genomfördes utifrån nätverksteorin, teorin om idésystem och socialpsykologi. I analysen på marknadsnivån tillämpades konkurrensstrategier, involveringsteorin, faktorer som påverkar köpbeslut och nätverksteorin. </p><p>Resultatet visar att Irradia möter hinder på marknadsnivån, framför allt när det gäller relationers betydelse i upphandlingsprocessen. Irradia AB har goda förutsättningar för att bemästra de flesta hindren, men relativt lite nätverkande har varit svagheten i den strategi som tillämpats hittills. Resultatet på meganivån visar att aktörerna anser att Mikael Bäckmans verksamhet på Audio Laser-Kliniken inte svarar mot vetenskap och beprövad erfarenhet. Därmed har experterna kunnat förklara laserbehandling av hörselsjukdomar som illegitim. Undersökningen visar dock att andra behandlingsmetoder på hörselområdet inte möter samma krav utifrån vetenskap och beprövad erfarenhet. Resultatet visar framför allt att liten tilltro till produkterna i expertnätverket sänker möjligheten till utbyte med den offentliga sjukvården. </p><p>Frågeställningen hade fokus på faktorer som är viktiga för nyetablerare på sjukvårdsmarknaden. Slutsatserna är att differentiering kan vara en lämplig strategi för företag med små resurser, och att utbildning som mervärde kan vara lämpligt om produkterna är komplexa. Nyetablerare bör satsa på löpande bearbetning av aktörer både på mega- och marknadsnivå. Undersökningen tyder dock på att bearbetningen på meganivå bör ske i första hand, för att nyetablerare skall kunna sälja nya produkter på den offentliga sjukvårdsmarknaden. </p> / <p>Irradia AB is a manufacturer and seller of medical, surgical and cosmetical laser instruments. So far the company has failed in establishing exchange with the public health services in Sweden. The purpose of this studie was to analyse and evaluate obstacles in the way of Irradias introduction on the public health service market. The medical lasers were chosen as the primary products to study. Due to the nature of the area of investigation, mega level marketing was separated from the market level. On the mega level, new and complex medical products must be approved by experts. On the market level, a comparison was made between Irradia and the public health service market. </p><p>The case study was chosen as a main method. Qualitative primary data was collected by interviewing. On the market level, interviews were conducted with Lars Hode, managing director of Irradia AB, Jan Svenonius, former director of purchasing at Huddinge Sjukhus and Mikael Wickström, director of purchasing at Karolinska Sjukhuset. On the mega-level, Audio Laser-Kliniken was chosen to represent Irradia, since their medical lasers are used for treatment of hearing disorders at the clinic. By using directive selection, the authors could quickly identify and interview persons who are negative when it comes to laser treatment of hearing disorders. </p><p>Competitive strategies, the involvement theory, network theory and factors influencing buyer behavior were applied in the market level analysis. The mega level analysis is based on the network theory, the theory of dominant ideas and social psychology. </p><p>Results of the market level analysis show that relations are of great importance in public health service purchasing processes. Irradia meets most of the basic conditions that are required for establishing exchange with the public health service market, but a relatively low degree of networking has been a flaw in the strategy that Irradia has had so far. Results of the mega level analysis show that the laser treatment of hearing disorders at Audio Laser-Kliniken does not comply with the requirements for an evidence-based medicine, according to the interviewees. Therefore laser treatment of hearing disorders has been announced illegitimate by the experts. The results also show that other treatment forms of hearing disorders can be difficult to evaluate regarding to the requirements of an evidence-based medicine. The results show, above all, that any possible distrust to the products among experts will have a negative impact on the possibility to establish exchange with the public health service market. </p><p>The question at issue focused on factors that are of importance for companies trying to establish exchange with the public health service market. Conclusions of the study show that differentiation can be a suitable strategy for establishers with new products, and that customer academies can be a relevant way to reduce risks if the products are complex. New companies should try to create relations on both the mega level and market level. The study shows that relations with experts on the mega level are critical for companies trying to sell new products to the public health service market. </p>
117

Fcγ Receptors in the Immune Response

Díaz de Ståhl, Teresita January 2001 (has links)
<p>Circulating immune complexes play an important role in the modulation of antibody responses and in the pathogenesis of immune diseases. This thesis deals with the <i>in vivo </i>regulatory properties of antibodies and their specific Fc receptors.</p><p>The immunosuppressive function of IgG is used clinically, to prevent rhesus-negative women from becoming sensitized to rhesus-positive erythrocytes from the fetus. The mechanism behind this regulation is poorly understood but involvement of a receptor for IgG, FcγRII, has been suggested. It is shown in this thesis that IgG and also IgE induce immunosuppression against sheep erythrocytes to a similar extent both in mice lacking all the known Fc receptors as in wild-type animals. These findings imply that antibody-mediated suppression of humoral responses against particulate antigens is Fc-independent and that the major operating mechanism is masking of epitopes.</p><p>Immunization with soluble antigens in complex with specific IgG leads to an augmentation of antibody production. The cellular mechanism behind this control is examined here and it is found that the capture of IgG2a immune complexes by a bone marrow-derived cell expressing FcγRI (and FcγRIII) is essential. An analysis of the ability of IgG3 to mediate this regulation indicated that, in contrast, this subclass of IgG augments antibody responses independently of FcγRI (and FcγRIII). These findings suggest that distinct mechanisms mediate the enhancing effect of different subclasses of antibodies.</p><p>Finally, the contribution of FcγRIII was studied in the development of collagen-induced arthritis (CIA), an animal model for rheumatoid arthritis in humans. It was discovered that while DBA/1 wild-type control mice frequently developed severe CIA, with high incidence, FcγRIII-deficient mice were almost completely protected, indicating a crucial role for FcγRIII in CIA.</p><p>The results presented here help to understand how immune complexes regulate immune responses <i>in vivo</i> and show that Fc receptors for IgG, if involved, could be new targets for the treatment of immune complex-related disorders.</p>
118

Regulatory Effects of TGF-β Superfamily Members on Normal and Neoplastic Thyroid Epithelial Cells

Franzén, Åsa January 2002 (has links)
<p>Thyroid growth and function is partly regulated by growth factors binding to receptors on the cell surface. In the present thesis, the transforming growth factor-β (TGF-β) superfamily members have been studied for their role in regulation of growth and differentiation of both normal and neoplastic thyroid epithelial cells.</p><p>TGF-β1 is a negative regulator of thyrocyte growth and function. However, the importance of other TGF-β superfamily members has not been fully investigated. TGF-β1, activin A, bone morphogenetic protein (BMP)-7 and their receptors were found to be expressed in porcine thyrocytes. In addition to TGF-β1, activin A was also found to be a negative regulator of thyroid growth and function, and both stimulated phosphorylation and nuclear translocation of Smad proteins. Furthermore, TGF-β1 and epidermal growth factor (EGF) demonstrated a synergistic negative effect on thyrocyte differentiation. Simultaneous addition of the two factors resulted in a loss of the transepithelial resistance and expression of the epithelial marker E-cadherin. This was followed by a transient expression of N-cadherin.</p><p>Despite the extremely malignant character of anaplastic thyroid carcinoma (ATC) tumor cells, established cell lines are still responsive to TGF-β1. A majority of the cell lines were also found to be growth inhibited by BMP-7. BMP-7 induced cell cycle arrest of the ATC cell line HTh 74 in a dose- and cell density-dependent manner. This was associated with upregulation of p21<sup>CIP1</sup> and p27<sup>KIP1</sup>, decreased cyclin-dependent kinase (Cdk) activity and hypophosphorylation of the retinoblastoma protein (pRb). TGF-β1, and to some extent also BMP-7, induced the expression of N-cadherin and matrix metalloproteinase (MMP)-2 and -9. Stimulation of HTh 74 cells with TGF-β1 increased the migration through a reconstituted basement membrane indicating an increased invasive phenotype of the cells.</p><p>Taken together, these data show that TGF-β superfamily members not only affect growth and function of normal thyroid follicle cells but may also, in combination with EGF, play a role in cell dedifferentiation. This study additionally suggests that the TGF-β superfamily members may be important for the invasive properties of ATC cells.</p>
119

Functional Significance of Multiple Poly(A) Polymerases (PAPs)

Nordvarg, Helena January 2002 (has links)
<p>3’ end cleavage and polyadenylation are important steps in the maturation of eukaryotic mRNAs. Poly(A) polymerase (PAP), the enzyme catalysing the addition of adenosine residues, exists in multiple isoforms. In this study the functional significance of multiple poly(A) polymerases have been investigated. It is concluded (i) that at least three mechanisms generate the multiple isoforms i.e. gene duplication, post-translational modification and alternative mRNA processing and (ii) that the different isoforms of poly(A) polymerases have different catalytic properties. The study highlights regulation of poly(A) polymerase activity through modulation of its affinity for the substrate as visualised by the K<sub>M</sub> parameter. We suggest that trans-acting factors modulating the K<sub>M</sub> of poly(A) polymerase will play important roles in regulating its activity.</p><p>A new human poly(A) polymerase (PAPγ) encoded by the PAPOLG gene was identified. PAPγ is 65% homologous to the previously identified PAP. In human cells three isoforms of poly(A) polymerases being 90, 100 and 106 kDa in sizes are present. These native isoforms were purified. The PAPOLA gene encoded the 100 and 106 kDa isoforms while the 90 kDa isoform was encoded by the PAPOLG gene. Native PAPγ was found to be more active than 100 kDa PAP while the hyperphosphorylated 106 kDa PAP isoform was comparably inactive due to a 500-fold decrease in affinity for the RNA substrate. </p><p>The PAPOLG gene was shown to encode one unique mRNA while the PAPOLA gene generated five different PAP mRNAs by alternative splicing of the last three exons. The PAPOLA encoded mRNAs were divided into two classes based on the composition of the last three exons. Poly(A) polymerases from the two classes were shown to differ in polyadenylation activities. These differences revealed two novel regulatory motifs in the extreme C-terminal end of PAP, one being inactivating and the other activating for polyadenylation activity.</p>
120

Studies on Human Endogenous Retroviruses (HERVs) with Special Focus on ERV3

Andersson, Ann-Catrin January 2002 (has links)
<p>Human endogenous retroviruses (HERVs) represent approximately 7% of the human genome. This investigation was focused on one particular HERV, ERV3, with the main purpose of characterising its gene expression patterns and genomic distribution of ERV3-like sequences. Furthermore, this careful expression study should provide insights into the biological role of HERVs. The impact of HERVs in health and disease is not yet clarified. ERV3 is expressed as three envelope (<i>env</i>) transcripts, of which two also contain a cellular gene, <i>H-plk</i> (human proviral linked <i>Krüppel</i>). ERV3 <i>env</i> expression was mainly investigated at the RNA level. The gene expression of two other HERVs, HERV-K and HERV-E was analysed and compared with ERV3 activity.</p><p>Real-time PCRs were developed and in combination with in situ hybridisation, it was found that ERV3 is expressed in a tissue- and cell-specific way. High levels of ERV3 mRNA (up to six times over Histone3.3) were demonstrated in placenta, sebaceous glands, foetal and adult adrenal glands, brown adipose tissue, corpus luteum, pituitary gland, thymus and testis. In monocytic cells including both normal monocytes and malignant U-937 cells, elevated mRNA levels were observed after retinoic acid (RA)-induced differentiation. ERV3-encoded Env protein was detected in selected cases, one following RA-treatment. In addition, several new ERV3-like sequences were discovered in the human genome. </p><p>ERV3 was found to have conserved open reading frames in contrast to other ERV3-like sequences in the human genome. This suggests that ERV3 may be involved in important cellular processes such as differentiation, cell fusion, immunomodulation and protection against infectious retroviruses. The developed techniques and obtained results will allow further studies of HERV expression to better correlate HERV activity to both normal development and disease. </p>

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