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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.
51

Non-Traditional Uses of the CCSDS Space Link Extension (SLE) Protocol

Safigan, Brian, Lokshin, Kirill, Puri, Amit 10 1900 (has links)
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Space Link Extension (SLE) is a set of Consultative Committee for Space Data Systems (CCSDS) recommended standards for extending the space link from ground stations to other spaceflight mission ground facilities over a ground network, allowing distributed access to space link telecommand and telemetry services. The currently defined and implemented SLE recommendations are oriented around a traditional CCSDS telecommand and telemetry protocol set, which uses discrete telecommand frames that are encapsulated in Communication Link Transmission Units (CLTUs) for transport over the ground segment, and telemetry data encapsulated in Transfer Frames at the spacecraft. This paper discusses several non-traditional uses of the SLE services. The applications addressed within lie outside the discrete packet telecommand/telemetry subset of the SLE recommendations that are fully defined by CCSDS. This paper will focus on the use of the currently implemented SLE model to enable the transport of other forms of data, which may be subject to various transmission constraints, across the ground segment.
52

Har D-vitamintillskott effekt vid behandling av Systemisk Lupus Erythematosus? : En litteraturstudie

Omoike, Gracious January 2019 (has links)
Introduktion: Systemisk Lupus Erythematosus är en prototypisk autoimmun sjukdom som gör att immunförsvarets antikroppar angriper kroppens egna vävnader, vilket leder till kronisk inflammation i kroppens organsystem. Idag finns ingen verksam behandling för Systemisk Lupus Erythematosus. Syftet med denna studie var att undersöka hur Dvitamintillskott påverkar Systemisk Lupus Erythematosus. Metod: Artiklarna hittades i databasen ”Pubmed” med sökningen ”Systemic Lupus Erythematosus and vitamin D supplementation”. Bland sökresultaten fanns sex relevanta artiklar som hade undersökt effekten av D-vitamintillskott på SLE. Resultat: Mer än hälften av patienterna i samtliga studier nådde serum 25(OH) D-nivåer som ansågs vara tillräckliga. D-vitamintillskottet minskade Th1/Th17-cellerna men ökade också Treg-celler och Th2-celler. Tre studier visade sig ha en signifikant minskning i sjukdomsaktivitet och anti-dsDNA antikroppar. Komplement C3 minskade i studie 2. Diskussion: Fem av studierna tyder på att oral administrering av D-vitamin tillskott har gett positiv inverkan på SLE. Två av de granskade studierna rapporterades inge positiv klinisk effekt hos deltagarna. Slutsats: D-vitamintillskott dämpar immunsystemet genom att öka Treg-celler och Th-2-celler men även minska Th1/Th17-celler och B-celler samt produktionen av autoantikroppar och anti-dsDNA-antikroppar. Effekten av D-vitamintillskott på komplement C3 och C4 är oklar. Det krävs dock fler studier med fler deltagarantal för att dra en slutsats om Dvitamintillskott kan användas som behandling för SLE. / Background: Systemic Lupus Erythematosus is a prototypical autoimmune disease in which antibodies attack healthy tissues in the body, causing inflammation in several organs. Aim: The aim of this literature study was to investigate the effect of Vitamin Dsupplementation on SLE. Method: The articles were searched in the database called ”Pubmed” using the search terms ”Systemic Lupus Erythematosus and Vitamin D supplementation”. Six of the articles which examined the effects of D-vitamin supplementation on SLE were relevant for this study. Result: More than half of the patients in all six studies reached sufficient serum 25(OH)D. Vitamin D-supplement reduced Th1/Th17-cells but increased Tregs-cells and Th2-cells. 3 studies showed a decrease in disease-activity and anti-dsDNA. C3 decreased in study 2. Discussion: Five studies indicated that the oral administration of vitamin-D supplementation had a positive effect on SLE. Two of the examined studies did not observe any clinical effect of the vitamin-D supplement. Conclusion: Vitamin-D supplement suppresses the immunesystem by increasing Treg cells and Th-2 cells but also reducing Th1/Th17-cells and B-cells as well as the production of autoantibodies and anti-dsDNA antibodies. The effect of vitamin D-supplement is unclear. More studies with more participants are required to determine if vitamin-D supplement can be used as a treatment for SLE.
53

Immune regulation induced by apoptotic cells in health and in systemic lupus erythematosus (SLE)

Simpson, Joanne Elizabeth January 2016 (has links)
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease where failure to remove apoptotic cells, due to a defect in phagocytic cells, or deficient opsonisation, leads to secondary necrosis and the release of DNA and chromatin. The nuclear constituents from apoptotic cells are targeted by autoantibodies, which form immune complexes. Immune complex-mediated TLR9 activation of plasmacytoid dendritic cells (pDCs) and subsequent secretion of interferon (IFN-α) is thought to drive inflammation in SLE. It is currently believed that pDCs do not normally respond to apoptotic cells, as self-DNA is hidden from TLR9. However, DNA and chromatin expressed on membrane bound apoptotic bodies is essential for inducing IL-10 secreting regulatory B cells through TLR9 stimulation. The overall objective of this thesis was to understand how apoptotic cells influence immune responses in health and in patients with SLE. Splenic mouse pDCs were activated with the synthetic TLR7 agonist R848 and TLR9 agonists CpGB and CpGA and were co-cultured with apoptotic cells, or with freeze-thawed necrotic cells. PDCs co-cultured with apoptotic cells down-regulated the expression of CD40 and CD86. When pDCs were activated by R848 or CpGB, IL-10, IFN-γ and IL-6 secretion was significantly induced in the presence of apoptotic cells. PDCs so cultured induced T cells to secrete immune-regulatory IL- 10. In contrast, co-culturing apoptotic cells with pDCs activated by CpGA, augmented IFN-α secretion. These cytokine responses by pDCs were only stimulated by DNA on whole apoptotic cells; not by free nucleic acids derived from necrotic cells. This data demonstrates that the inflammatory context in which pDCs sense whole apoptotic cells is crucial to determining the threshold of tolerance to apoptotic self. It questions the perception that pDCs see all apoptotic cells and their necrotic cellular debris as dangerous and suggests that there may be something intrinsically different about SLE apoptotic cells, which causes inflammation. SNPs near ATG5, a protein of the cell survival pathway autophagy, have been linked to SLE susceptibility, but the role of autophagy in SLE pathogenesis is unclear. We hypothesised that dysfunctional autophagy is linked to abnormal apoptosis of SLE lymphocytes. Western blotting revealed that ATG5-ATG12 protein complex expression was significantly reduced in SLE lymphocytes and they failed to convert LC3-I to LC3- II, the hallmark of a functioning autophagy pathway, which caused accelerated secondary necrosis. Apoptotic SLE lymphocytes had an impaired ability to stimulate IL-10 secreting regulatory B cells and they induced pro-inflammatory cytokine secretion by monocyte-derived macrophages. Phagocytosis of apoptotic SLE lymphocytes by healthy macrophages was also impaired; however this was independent of ATG5 protein expression. The novel findings of this thesis suggest SLE apoptotic lymphocytes are intrinsically pro-inflammatory, which may be caused by diminished autophagy leading to an inability of lymphocytes to correctly execute apoptosis. Furthermore, inefficient clearance of SLE apoptotic cells results from a defect in the apoptotic cell, rather than the phagocytic cell.
54

Influence of Epstein-Barr Virus on Systemic Lupus Erythematosus Disease Development and the Role of Depression on Disease Progression

Cornaby, Caleb 01 December 2017 (has links)
Systemic Lupus Erythematosus (SLE) is an autoimmune disease affecting 20 to 250 individuals per 100,000 worldwide. Symptomology includes dermatological manifestations such as discoid lesions, acute cutaneous rashes, and oral and nasal ulcers, along with musculoskeletal, pulmonary, and renal complications. Abnormal T and B lymphocyte function and apoptosis, immune complex clearance, complement function, and nucleosome processing are typical of disease pathophysiology. SLE is the result of both environmental and genetic factors, which together create the conditions leading to disease onset and progression. Of these environmental factors, Epstein-Barr virus (EBV) infection is known to cause the genesis of cross-reactive antibodies in SLE prone individuals that can initiate disease activity. Viral infection and modulation of cellular genes is important in understanding the microenvironment that could lead to immune mis-regulation and the inception of lupus in those individuals at risk. During disease development, a variety of variables assist and detract from disease progression and the quality of life experienced by SLE patients. Research into EBV-infected naïve B lymphocytes revealed that EBV modulates the chemotactic receptor EBI2 during viral infection via the BRRF1 viral gene product Na. This likely changes B lymphocyte chemotaxis in secondary tissue in virally infected B cells. Current literature suggests this results in sequestration of cells to peripheral areas of the tissue and mis-regulation of the immune response. It is not uncommon for SLE patients to have neuropsychiatric disorders due to lupus disease activity. With SLE patients being up to 6 times more at risk for depression, recognition and treatment of depression and anxiety have been shown to improve quality of life, pain, and treatment outcomes. Two studies investigate both clinical laboratory and psychosocial assessment variables that we suspect to be correlated with depression in patients with SLE. Univariate and multivariate analysis from our first study identified an array of variables that show strong associations with depression, including: Body Mass Index, Pain, Total Complement, fatigue assessments, and SF-36 scores. The second study found similar associations, but further found that serum IL-10 levels demonstrated a strong correlation with depression in SLE patients. In this final study SLE patients are compared alongside healthy, clinically depressed, and rheumatoid arthritis patients to provide evidence that increased depression in SLE patients is due more to disease pathology than a result of chronic inflammation.
55

Optimal Control Theory and Estimation of Parameters in a Differential Equation Model for Patients with Lupus

Agaba, Peter 01 April 2019 (has links)
System Lupus Erythematosus (SLE) is a chronic inflammatory autoimmune disorder that affects many parts of the body including skin, joints, kidneys, brains and other organs. Lupus Nephritis (LN) is a disease caused by SLE. Given the complexity of LN, we establish an optimal treatment strategy based on a previously developed mathematical model.For our thesis work, the model variables are: Immune Complexes (I), Pro-inflammatory mediators (P), Damaged tissue (D), and Anti-inflammatory mediators (A). The analysis in this research project focuses on analyzing therapeutic strategies to control damage using both parameter estimation techniques (integration of data to quantify any uncertainties associated with parameters) and optimal control with the goal of minimizing time spent on therapy for treating damaged tissue by LN.
56

Deux applications du chaos quantique : etude des fonctions d'ondes aleatoires via SLE et description de cavites dielectriques

Dubertrand, R. 23 September 2008 (has links) (PDF)
Au cours de cette thèse, nous avons étudié deux problèmes spécifiques de chaos quantique. D'abord, nous avons confirmé le modèle de percolation critique pour décrire statistiquement les lignes nodales des fonctions d'onde de systèmes classiquement chaotiques. Dans ce but, les lignes ont été décrites à l'aide d'un processus de Schramm-Loewner et notre étude numérique concorde avec le récent théorème liant ce processus et la percolation au seuil critique. Dans une seconde partie nous avons généralisé les résultats connus en chaos quantique sur les billards fermés aux cavités diélectriques ouvertes. Nous avons donné des formules générales pour une légère pertubation d'une cavité circulaire et proposé une généralisation de formule de trace pour ces systèmes. En particulier nous donnons les premiers termes de la série de Weyl pour compter le nombre de résonances d'une cavité diélectrique. Ces résultats sont en accord avec les mesures expérimentales et nos calculs numériques. Ces deux études montrent le caractère fondamental et transversal des techniques du chaos quantique pour les problèmes actuels.
57

Alternativ splicing i mänsklig sjukdom

Edin, Joel January 2010 (has links)
<p>Exoner är de sekvenser i DNA vilka rymmer koden för proteiner i människan och i alla andra organismer. Intronerna, vilka utgör utrymmet mellan exoner, består av ickekodande sekvenser och kontrollelement. Exoner tillhörande en gen måste inte alltid inkluderas i den slutliga mRNA produkten, alternativ splicing tillåter exkludering av vissa sekvenser och gör att en gen kan ha mer än en mRNA produkt, därigenom kan en gen koda för flera olika proteiner. Alternativ splicing är ett fält som snabbt utvecklas och dess relevans för många sjukdomar har blivit uppenbar. Detta arbete går igenom ett flertal av dessa sjukdomar för att sammanställa ny forskning och tydliggöra rollen av alternativ splicing i dem. De sjukdomar som undersökts är cystisk fibros, ärftlig frontotemporal dementia, systemisk lupus erythematosus, aniridi, myotonisk dystrofi, amyotrophic lateral sclerosoch familial dysautonomia. Dessa sjukdomar har involvering av alternativ splicing, de genetiska processerna bakom dem är dock mycket olika och kan visa på de många sätt alternativ splicing kan påverka cell och kroppsfunktion. Målet med arbetet är en översiktlig bild av framstegen som gjorts och vilken forskning som nu bedrivs.</p>
58

Defining the genetics of systemic autoimmunity in mouse models of lupus

Haraldsson, Katarina January 2008 (has links)
Systemic Lupus Erythematosus (SLE) is a chronic multi-organ autoimmune disease considered a prototype for autoantibody and immune complex-mediated tissue injury. Although autoantibodies against a wide diversity of self-antigens are characteristically found in this disease, an important hallmark is the presence of autoantibodies to nuclear antigens. Despite this common clinical feature, individual patients vary widely in the organ systems afflicted, disease severity, disease course, and response to treatment. These characteristics make clinical management of SLE challenging and highlight the need for effective and less toxic therapeutic interventions. Susceptibility to lupus has been shown in both human studies and mouse models to be dependent on genetic predisposition. Therefore, it is likely that knowledge of the genetic basis of SLE will be required before full understanding of SLE pathogenesis can be achieved. In this thesis, studies to define the genetic basis of lupus in an induced and two spontaneous models of the disease are presented. These studies encompass mapping, characterization of interval congenic mice, and cloning of the Lmb3 locus gene. In the first study, a genomewide mapping study was performed to define the genetic basis for resistance of the DBA/2 mice to mercury-induced autoimmunity. On chromosome 1, a single quantitative trait was linked with resistance to HgIA. These results linked the locus Hmr1 to a late stage of lupus with GN. Interval congenic mice are important tools to define and characterize the roles of different loci in lupus-like diseases. The second paper identifies the effect of NZB and NZW Lbw2 alleles on lupus susceptibility by using BWF1 mice with none, one or two copies of the lupus-predisposing NZB.Lbw2 locus. The lack of the NZB locus significantly reduced mortality, GN and B cell activation. IgM anti-chromatin levels in genome-wide mapping was linked only to Lmb2 and none of the known B cell hyperactivity-promoting genes were present in this location, which might indicate a novel B cell activation gene. The third study used reciprocal single locus interval-specific congenic mice to characterize the contribution of Lmb1-4 on the MRL-Faslpr and B6-Faslpr backgrounds. The Lmb3 locus on chromosome 7 was found to have the most prominent phenotype with clear effects on lymphoproliferation, GN and mortality. In the fourth paper the Lmb3 was cloned and shown to be a spontaneous nonsense mutation in the Coro1a gene that encodes an actin-binding and -regulatory protein. Upon further characterization, this genetic alteration was discovered to be a new lupus suppressing mutation that reduced T cell migration, activation, and survival. Our findings highlight the complexity of the genetics of lupus, and further suggest that genes involved in controlling the actin cytoskeleton might be potential targets for autoimmune therapeutics.
59

The PD-1 pathway and the complement system in systemic lupus erythematosus

Kristjánsdóttir, Helga January 2009 (has links)
Autoimmune diseases occur in up to 3-5% of the general population and represent a diverse collection of diseases with regards to clinical manifestations. The unifying factor of autoimmune diseases is tissue and organ damage as a result of an immune response mounted against self-antigens. Systemic lupus erythematosus (SLE) is considered a prototype of human systemic autoimmune diseases. The etiology of SLE is as yet largely unknown, but both epidemiological and genetic data suggest an interplay between numerous and varying genetic and environmental factors. There is compelling evidence for a strong genetic component in SLE. The disease has a high λsibs value and familial clustering is apparent. Multiple susceptibility loci have been identified, some of which are syntenic between humans and mice and some of which overlap with other autoimmune diseases.   This thesis is based on analysis of Icelandic multicase SLE families and Swedish SLE patients. Paper I is a study of the association of C4A protein deficiency (C4AQ0) with SLE in the multicase families and shows a significantly increased frequency of C4AQ0 in the families. The genetic basis for C4AQ0 varies and C4AQ0 is found on different MHC haplotypes, pointing to C4AQ0 as an independent risk factor for SLE. Paper II describes the association of low MBL serum levels with SLE in the families and identifies low MBL as risk factor for SLE in families that carry the defect. Low MBL was furthermore found to mediate an additive risk when found in combination with C4AQ0. In paper III cellular expression the PD-1 co-inhibitory receptor on T cells was studied. A polymorphism in the PDCD1 gene, PD-1.3A was previously associated with SLE in the multicase families. The polymorphism is thought to disrupt expression of the gene and may lead to decreased expression of the PD-1 receptor. The study demonstrates lower PD-1 expression in SLE patients and relatives in correlation to the PD-1.3A genotype. Paper IV is a compiled analysis of the SLE families, including PD-1.3A, C4AQ0, low MBL, autoimmune diseases and autoantibody profiles. The study demonstrates clustering of different autoimmune diseases and autoantibodies in families that are heterogenic with regards to the genetic susceptibility factors, PD-1.3A, C4AQ0 and low MBL.
60

Genetic Risk Factors for Systemic Lupus Erythematosus : From Candidate Genes to Functional Variants

Abelson, Anna-Karin January 2008 (has links)
The aim of this thesis has been to identify genetic variants that increase the susceptibility for Systemic Lupus Erythematosus (SLE), an autoimmune disease caused by a complex interplay between various genetic and environmental factors. Five different candidate genes were selected through different strategies, and were analysed for association with SLE in an attempt to distinguish some of the underlying mechanisms of this disease. Two of these genes, PD-L1 and PD-L2, appeared not to contain any major risk factors for SLE in the analysed European and Latin American populations. In two other genes, CD24 and STAT4, there appeared to be population-specific effects. The A57V amino acid substitution in the CD24 gene, previously implicated with multiple sclerosis, was associated in a Spanish cohort, with a weak trend in German samples, and no association in Swedish. The previously reported and highly convincing association of the STAT4 transcription factor gene was confirmed in all our cohorts. Interestingly, the results indicate the presence of at least two independent risk variants: the first, represented by a previously reported SNP, was the strongest in individuals of Northern European ancestry, and the second was more pronounced in individuals from Southern Europe and Latin America. We also report the identification of a novel susceptibility gene. The BANK1 gene, encoding a scaffold protein involved in B-cell activation, contains functional variants affecting important domains, which are associated in all investigated cohorts from Europe and Latin America. These results confirm the existence of replicable associations between genetic variants and SLE, which are common and present in many populations. The results also illustrate a certain degree of heterogeneity, where some risk factors could have variable effect in different populations.

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