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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.
151

Tissue distribution and characteristics of canine non-conventional T cells

Rabiger, Friederike Veronika 07 July 2021 (has links)
Einleitung: Zu den konventionellen αβ T-Zellen zählen die klassischen CD4+ einfach-positiven T-Helfer (Th) bzw. regulatorischen T-Zellen (Treg) sowie CD8αβ+ einfach-positive zytotoxische T-Zellen. Säugetiere besitzen jedoch noch weitere T-Zell-Subpopulationen, die entweder den T-Zell-Rezeptor αβ (TCRαβ) oder γδ (TCRγδ) exprimieren. Bei Hunden wurde bisher nur die hoch aktivierte CD4+CD8α+ doppelt-positive (dp) T-Zellpopulation des peripheren Blutes detailliert charakterisiert. Über ihre Verteilung in lymphatischem und nicht lymphatischem Gewebe ist jedoch wenig bekannt. Darüber hinaus besitzen Hunde αβ T-Zellen, die weder CD4 noch CD8α (CD4-CD8α- doppelt-negative (dn) T-Zellen) exprimieren, sowie γδ T-Zellen, deren Phänotyp bisher noch nicht untersucht wurde. Ziele der Studie: Ziel dieser Studie war es, einen Überblick über das Vorkommen und den Phänotyp von nichtkonventionellen T-Zellen im peripheren Blut und Geweben des Hundes zu bieten. Zu diesem Zweck wurden CD4+CD8α+ dp, TCRαβ+CD4-CD8α- dn und γδ T-Zellen hinsichtlich der Expression von Oberflächenmarkern, wichtigen Transkriptionsfaktoren und Zytokinen charakterisiert. Tiere, Material und Methoden: Canine T-Zellen Zellen aus dem Blut (Stichprobenumfang: n = 10) sowie aus den Peyerschen Platten (PP; n = 10), dem Dünndarmepithel (IEL; n = 6), den mesenterialen Lymphknoten (mLN; n = 10), tracheobronchialen Lymphknoten (tLN; n = 9), der Lunge (n = 10), Milz (n = 10) und dem Thymus (n = 10) wurden mittels Durchflusszytometrie analysiert. Das Studiendesign erforderte, dass die Gewebeproben von einer anderen Gruppe gesunder Beagle-Hunde (n = 12) entnommen wurden als das periphere Blut. CD4+CD8α+ dp T-Zellen wurden auf ihre Gewebeverteilung, die Expression des T-Zell-Rezeptortyps und die Zusammensetzung des CD8-Dimers (d.h. CD8αα Homodimer vs. CD8αβ Heterodimer) sowie die Expression des Aktivierungsmarkers CD25 untersucht. Um Hinweise auf die potenzielle(n) Funktion(en) von CD4+CD8α+ dp T-Zellen in Geweben zu erhalten, wurde die Expression des Transkriptionsfaktors Forkhead Box P3 (FoxP3) und des zytotoxischen Moleküls Granzym B analysiert. Darüber hinaus wurden Gewebe und Blut auf die Verteilung von TCRαβ+CD4-CD8α- dn und γδ T-Zellen untersucht. Eine umfassende Charakterisierung von TCRαβ+CD4-CD8α- dn und γδ T-Zellen des peripheren Blutes erfolgte durch die Untersuchung der folgenden Marker: CD25 und CD5, FoxP3, GATA-3, T-Box-Transkriptionsfaktor TBX21 (T-bet) und Granzym B. Im Rahmen funktioneller Analysen wurde die Zytokinproduktion (Interferon-γ (IFN-γ) und Interleukin-17A, IL-17A) nach Stimulation der Zellen mit Phorbol-Myristat-Acetat (PMA)/Ionomycin durchgeführt. Normalverteilte Datensätze wurden mittels einfaktorieller Varianzanalyse (ANOVA) mit Bonferroni-Post-Hoc-Test (Vergleich mehrerer Gruppen) oder ungepaartem t-Test (zweiseitig; Vergleich zweier Gruppen) analysiert. Bei nichtparametrischen Daten wurde entweder der Kruskal-Wallis H-Test mit Dunn's Post-Test (Ver-gleich mehrerer Gruppen) oder der Mann-Whitney U-Test (zweiseitig; Vergleich zweier Gruppen) angewandt. Ergebnisse: Canine CD4+CD8α+ dp T-Zellen der Gewebe sind hauptsächlich TCRαβ+CD4+CD8αα+CD25+ und akkumulieren in den PP (durchschnittlich 1.6 %). Obwohl CD4+CD8α+ dp T-Zellen der LN CD4 und CD8α nicht gleich stark exprimieren und zahlenmäßig gering (durchschnittlich 0,2 %) sind, sind sie teilweise FoxP3+. Dies weist auf ein regulatorisches Potential dieser Untergruppe hin. Einige CD4+CD8α+ dp T-Zellen der IEL exprimieren TCRγδ und/oder Granzym B, was die Einzigartigkeit der intestinalen intraepithelialen Lymphozyten unterstreicht. TCRαβ+CD4-CD8α- dn T-Zellen machen einen wesentlichen Anteil aller αβ T-Zellen in Blut (Median 14,4 %) und Gewebe (Median 15 % (Lunge) - 7,5% (PP)) aus und besitzen ein bemerkenswert hohes Expressionsniveau an CD25. CD25 wird entweder mit FoxP3 (hinweisend auf einen regulatorischen Phänotyp) oder ohne FoxP3 (hinweisend auf einen Effektorphänotyp) exprimiert. Zusätzlich weisen IFN-γ, GATA-3 oder IL-17A-exprimierende Subpopulationen Eigenschaften von konventio-nellen Typ 1 T-Helferzellen (Th1), Th2 bzw. Th17 auf. Interessanterweise wurden auch FoxP3+GATA-3+-Hybridzellen gefunden. Canine γδ T-Zellen hingegen sind entweder CD8α+ einfach-positiv oder CD4 CD8α- dn. Während TCRγδ+CD8α+ einfach-positive T-Zellen ihren zytotoxischen TCRαβ+CD8αβ+ T-Zell-Pendants ähneln (T-bet+, IFN-γ+, Granzym B+), exprimieren TCRγδ+CD4 CD8α- dn T-Zellen GATA-3 und nur geringe Mengen an T-bet und Granzym B. Schlussfolgerungen: Dies ist die erste Studie, die einen umfassenden Überblick über nichtkonventionelle T-Zell-Populationen des Hundes bietet. Hinsichtlich ihrer Gewebeverteilung, ihrer Anzahl und ihres funktionellen Potentials ist es wahrscheinlich, dass diese Zellen an wichtigen Immunreaktionen sowie an der Pathogenese von Erkrankungen des Hundes beteiligt sind. Hierzu werden weitere Studien erforderlich sein. Es ist anzumerken, dass das klassische Schema der CD4+ und CD8αβ+ einfach-positiven T-Zellen als canine Haupteffektor- bzw. regulatorische T-Zellen neu überdacht werden sollte. :1 Introduction 1 1.1 The innate and adaptive immune system of mammals 1 1.2 Conventional αβ T cells 1 1.2.1 Cytotoxic CD8αβ+ T cells 2 1.2.2 CD4+ T cells 3 1.2.2.1 CD4+ T helper cells 3 1.2.2.2 CD4+ regulatory T cells 4 1.3 Non-conventional T cells 5 1.3.1 CD4+CD8α+ double-positive T cells 5 1.3.2 γδ T cells 7 1.3.3 CD4-CD8α- double-negative αβ T cells 8 1.4 Aims of this study 8 2 Results 10 2.1 1st publication 10 2.2 2nd publication 32 3 Discussion 55 3.1 Canine non-conventional CD4+CD8α+ double-positive T cells are a homogeneous population enriched at mucosal sites 55 3.2 Canine non-conventional CD4-CD8α- double-negative T cells are unique in abundance and phenotype 57 3.3 Concluding remarks 60 4 Summary 61 5 Zusammenfassung 63 6 Literature Cited 65 / Introduction: Conventional αβ T cells comprise the classical CD4+ single-positive (sp) T helper (Th) resp. T regulatory (Treg) and CD8αβ+ sp cytotoxic T cell subsets. However, further T cell subpopulations either expressing T cell receptor αβ (TCRαβ) or γδ (TCRγδ) occur in mammals. In dogs, only the highly activated CD4+CD8α+ double-positive (dp) T cell population of peripheral blood has been characterized in detail. Yet, little is known about its distribution in lymphoid and non-lymphoid tissues. Furthermore, dogs possess αβ T cells neither expressing CD4 nor CD8α (CD4-CD8α- double-negative (dn) T cells) and γδ T cells, whose phenotype was still undefined. Aims of study: The objective of this study was to provide an overview on the occurrence and phenotype of non-conventional T cells in canine peripheral blood and tissues. To this end, CD4+CD8α+ dp, TCRαβ+CD4-CD8α- dn, and γδ T cells were characterized regarding expression of surface markers, key transcription factors, and cytokines. Animals, material and methods: Canine T lymphocytes from peripheral blood (sample size: n = 10), Peyer’s patches (PP; n = 10), epithelium of the small intestine (IEL; n = 6), mesenteric lymph nodes (mLN; n = 10), tracheobronchial lymph nodes (tLN; n = 9), lung (n = 10), spleen (n = 10), and thymus (n = 10) were analyzed by flow cytometry. Due to the study design tissue samples had to be taken from a different group of healthy Beagle dogs (n = 12) than peripheral blood. CD4+CD8α+ dp T cells were studied for their tissue distribution, expression of T cell receptor type and composition of the CD8 dimer (i.e. CD8αα homodimer vs. CD8αβ heterodimer), as well as expression of the activation marker CD25. To define the potential function(s) of CD4+CD8α+ dp T cells in tissues, expression of the transcription factor forkhead box P3 (FoxP3) and the cytotoxic molecule granzyme B were analyzed. Furthermore, tissues and blood were studied for distribution of TCRαβ+CD4-CD8α- dn and γδ T cells. A comprehensive characterization of blood TCRαβ+CD4-CD8α- dn and γδ T cells was made by investigation of the following markers: CD25 and CD5, FoxP3, GATA-3, T-box transcription factor TBX21 (T-bet), and granzyme B. Functional analyses were performed by examination of cytokine production (interferon γ (IFN-γ) and interleukin 17A, IL-17A) following stimulation of cells with phorbol-myristate-acetate (PMA)/ionomycin. Normally distributed data sets were analyzed using One-way analysis of variance (ANOVA) with Bonferroni post hoc test (multiple groups) or unpaired Student’s t-test (two-tailed; two groups). For nonparametric data, either Kruskal-Wallis H test with Dunn’s post-test (multiple groups) or Mann-Whitney U test (two-tailed; two groups) was applied. Results: Canine CD4+CD8α+ dp T cells of tissues can be mainly described as TCRαβ+CD4+CD8αα+CD25+ accumulating in PP (1.6% on average). Although not homogeneous in expression levels of CD4 and CD8α and low in number (0.2% on average), CD4+CD8α+ dp T cells of LN are partly FoxP3+. This indicates regulatory potential of this subset. Some CD4+CD8α+ dp T cells of IEL express TCRγδ and/or granzyme B, underlining the uniqueness of intestinal intraepithelial lymphocytes. TCRαβ+CD4-CD8α- dn T cells make up a substantial portion of all αβ T cells in blood (median 14.4%) and tissues (median 15% (lung) – 7.5% (PP)) with a remarkably high expression level of CD25. CD25 is either co-expressed with FoxP3 (reminiscent of a regulatory phenotype), or without FoxP3 (reminiscent of an effector phenotype). In addition, subsets expressing IFN-γ, GATA-3, or IL-17A suggest properties of conventional type 1 T helper cells (Th1), Th2, and Th17, respectively. Interestingly, FoxP3+GATA-3+ hybrid cells were found, too. Canine γδ T cells, on the other hand, are either CD8α+ sp or CD4-CD8α- dn. While TCRγδ+CD8α+ sp T cells resemble their TCRαβ+CD8αβ+ cytotoxic T cell counterparts (T-bet+, IFN-γ+, granzyme B+), TCRγδ+CD4-CD8α- dn T cells express GATA-3, and only low levels of T-bet and granzyme B. Conclusions: This is the first study providing a comprehensive overview on canine non-conventional T cell subsets. Regarding tissue distribution, abundance and functions resp. functional potential of these T cells, it is conceivable that they play a major role in health and diseases of dogs. Further studies examining this topic will be needed. Of note, the classical scheme of CD4+ sp Th/Treg and CD8αβ+ cytotoxic T cells as main effector/regulatory T cells in dogs should be reconsidered.:1 Introduction 1 1.1 The innate and adaptive immune system of mammals 1 1.2 Conventional αβ T cells 1 1.2.1 Cytotoxic CD8αβ+ T cells 2 1.2.2 CD4+ T cells 3 1.2.2.1 CD4+ T helper cells 3 1.2.2.2 CD4+ regulatory T cells 4 1.3 Non-conventional T cells 5 1.3.1 CD4+CD8α+ double-positive T cells 5 1.3.2 γδ T cells 7 1.3.3 CD4-CD8α- double-negative αβ T cells 8 1.4 Aims of this study 8 2 Results 10 2.1 1st publication 10 2.2 2nd publication 32 3 Discussion 55 3.1 Canine non-conventional CD4+CD8α+ double-positive T cells are a homogeneous population enriched at mucosal sites 55 3.2 Canine non-conventional CD4-CD8α- double-negative T cells are unique in abundance and phenotype 57 3.3 Concluding remarks 60 4 Summary 61 5 Zusammenfassung 63 6 Literature Cited 65
152

OLEDs: Light-emitting thin film thermistors revealing advanced selfheating effects

Fischer, Axel, Koprucki, Thomas, Glitzky, Annegret, Liero, Matthias, Gärtner, Klaus, Hauptmann, Jacqueline, Reineke, Sebastian, Kasemann, Daniel, Lüssem, Björn, Leo, Karl, Scholz, Reinhard 29 August 2019 (has links)
Large area OLEDs show pronounced Joule self-heating at high brightness. This heating induces brightness inhomogeneities, drastically increasing beyond a certain current level. We discuss this behavior considering 'S'-shaped negative differential resistance upon self-heating, even allowing for 'switched-back' regions where the luminance finally decreases (Fischer et al., Adv. Funct. Mater. 2014, 24, 3367). By using a multi-physics simulation the device characteristics can be modeled, resulting in a comprehensive understanding of the problem. Here, we present results for an OLED lighting panel considered for commercial application. It turns out that the strong electrothermal feedback in OLEDs prevents high luminance combined with a high degree of homogeneity unless new optimization strategies are considered.
153

Active dielectrophoretic trapping for deterministic single-cell encapsulation in droplet microfluidics

Surana, Prasanna January 2023 (has links)
The research work focuses on optimizing various parameters for controlling cells using negative dielectrophoresis and entrapping them in droplet microfluidics. This is achieved by developing a conductivity medium, combining CytoRecovery, BSA, and EDTA, to maintain a steady count of single cells with good viability over an extended period. The study involves the optimization of frequency and voltage applied to the electrodes to achieve the desired dielectrophoretic forces for long-term cell manipulation. The optimization is based on simulations performed using myDEP and COMSOL software. Additionally, the stability of the conductivity medium is tested during prolonged electric field applications. Considering the significance of working with cells, ensuring the temperature inside the channels remains within physiological limits is vital. Both COMSOL simulations and physical experiments using Rhodamine B dye are conducted to achieve this objective. Moreover, a well-designed process flow is proposed for performing cellular entrapment in droplets. Finally, a novel microfluidic cleaning protocol has been developed to efficiently eliminate both non-biological and biological contaminants from the microfluidic chamber. This innovative protocol has the potential to enable the reuse of any microfluidic chip that does not possess a functionalized surface. / Forskningsarbetet fokuserar på att optimera olika parametrar för att kontrollera celler med hjälp av negativ dielektrofores och fånga in dem i droppmikrofluidik. Detta uppnås genom att utveckla ett konduktivitetsmedium, som kombinerar CytoRecovery, BSA och EDTA, för att upprätthålla ett jämnt antal enstaka celler med god livsduglighet under en längre period. Studien involverar optimering av frekvens och spänning som appliceras på elektroderna för att uppnå de önskade dielektroforetiska krafterna för långvarig cellmanipulation. Optimeringen är baserad på simuleringar utförda med mjukvaran myDEP och COMSOL. Dessutom testas konduktivitetsmediets stabilitet under långvariga elektriska fälttillämpningar. Med tanke på betydelsen av att arbeta med celler är det viktigt att se till att temperaturen inuti kanalerna håller sig inom fysiologiska gränser. Både COMSOL-simuleringar och fysiska experiment med Rhodamine B-färgämne genomförs för att uppnå detta mål. Dessutom föreslås ett väldesignat processflöde för att utföra cellulär infångning i droppar. Slutligen har ett nytt mikrofluidrengöringsprotokoll utvecklats för att effektivt eliminera både icke-biologiska och biologiska föroreningar från mikrofluidkammaren. Detta innovativa protokoll har potential att möjliggöra återanvändning av alla mikrofluidiska chip som inte har en funktionaliserad yta.
154

Residual density validation and the structure of Labyrinthopeptin A2 / Residualdichtevalidierung und die Struktur von Labyrinthopeptin A2

Meindl, Katharina Anna Christina 30 October 2008 (has links)
No description available.
155

Värmland levande skogar : En jämförande fallstudie om hur kommunerna Sunne och Karlstad implementerar det svenska miljömålet Levande skogar i deras samhällsplanering. / Värmlands living forests : A comparative case study of how the municipalities Sunne and Karlstad implement the Swedish climate goal Living forests in their urban planning

Enqvist, Patricia January 2022 (has links)
Genom Agenda 2030 skapades Sveriges 16 miljömål och ett av dessa miljömål uppnås inte i dagsläget är målet Levande skogar. Trots befintliga åtgärder har miljömålet en fortsatt negativ utveckling, för att bevara skogens biologiska och kulturella värden krävs förstärkta åtgärder och styrmedel. En kommunal nivå är viktig för implementeringen av miljömålet genom samhällsplanering. Syftet med studien är att skapa förståelse för hur Sunne och Karlstad kommun prioriterar och värderar skogen i deras samhällsplanering genom att genomföra en jämförande fallstudie och analysera utifrån en syntetisk top-down/bottom-up teoretisk implementeringsmodell och även granska likheter och skillnader mellan detaljplanerna. Uppsatsens frågeställningar följer: • Reflekteras de politiska argumenten angående miljömålet levande skogar genom implementeringsprocessen inom stadsplanering? • Finns ett tydligt arbete i planeringsprocessen i Sunne och Karlstad kommun som strävar efter att uppnå miljömålet levande skogar?  • Vilka prioriteringar inom samhällsplanering görs i förmån till skogen i Sunne och Karlstad kommun? Studiens resultat visar att implementeringsprocessen inom stadsplanering påverkas av de politiska argumenten angående miljömålet Levande skogar. Samarbetet mellan olika nivåer inom implementeringen som involverar organisationer och aktörer från ett beslutande av en policy till genomförandet på lokal nivå är viktigt för hur det sedan implementeras i samhällsplaneringen. Policyn för Levande skogar diskuteras inte specifikt i någon av detaljplanerna, men flera delar av planerna berör ändå detta policyområde. Det finns flera likheter och skillnader mellan detaljplanerna i Sunne och Karlstad kommun när det gäller arbetet med frågor kopplade till natur och skog. I Sunne kommun finns det en tydlig prioritering av att bevara skogen och dess naturvärden. I Karlstad kommun genomförs skogliga åtgärder för att utveckla trygghet, upplevelse, funktion och trivsel för människor, djur och växtlighet i tätortsnära skog enligt kommunen. / Through Agenda 2030, Sweden developed 16 environmental goals. One of these environmental goals that are currently not reached is the Living Forests goal. Despite existing measures, the goal has continued negative development. To preserve the forest's biological and cultural values, strengthened measures and instruments are required. The municipal level is essential for implementing the environmental objective through community planning. The case study's intent is to develop a deeper understanding of how the municipalities of Sunne and Karlstad prioritize and value the forest in their urban planning. Conducting a comparative case study and analysing based on a synthetic top-down/bottom-up theoretical implementation model and reviewing similarities and differences between the detailed plans. The case study's questions follow:  • Are the political arguments regarding the environmental goal of living forests reflected through the implementation process in urban planning? • Is the work evident in the planning process in Sunne and Karlstad municipalities that strive to achieve the environmental goal of living forests?  • What priorities in urban planning are made in favour of the forest in Sunne and Karlstad municipalities? The results show that the implementation process in urban planning is influenced by the political arguments regarding the environmental goal of Living Forests. The cooperation between different levels within the implementation that involves organizations and actors, from the decision of a policy to the implementation at the local level, is essential for how it implements in community planning. The Living Forests policy is not addressed in any of the detailed plans, but several parts of both plans still touch on this policy area. There are several similarities and differences between the detailed planning documents in both municipalities regarding the work with topics connected to nature and forests. Sunne municipality has a clear priority to preserve the forest and its natural values. In Karlstad municipality, forestry measures are carried out to develop safety, experience, function, and well-being for people, animals, and vegetation in forests close to urban areas, according to the municipality.

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