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In dieser Arbeit wurde einerseits retrospektiv untersucht, wie sich supratentorielle und infratentorielle Ependymome bildmorphologisch unterscheiden, ob Lokalrezidive eines Ependymoms dessen Bildeigenschaften teilen und welche Art von Rezidiven im Verlauf auftreten können. Die von uns beschriebenen Bildcharakteristika der Ependymome decken sich zum größten Teil mit bereits veröffentlichten Studien. Supratentorielle Ependymome unterscheiden sich signifikant in ihrer Bildmorphologie im Vergleich zu Ependymome der hintern Schädelgrube. Alle pädiatrischen Ependymompatienten/innen in unserem Kollektiv erkrankten an mindestens einem Rezidiv. Am häufigsten traten Lokalrezidive gefolgt von Meningeosen im ersten Rezidiv auf. Seltener fanden sich transiente postradiogene Läsionen, Diffuse intrinsische Ponsgliome und extraneurale Metastasen. Der bildmorphologische Vergleich, Primarius versus Lokalrezidiv ergab überwiegend ähnliche bildgebende Eigenschaften vor allem im Signalverhalten, Tumorbegrenzung und KM-Aufnahme sowie KM anreichernder Tumoranteil. Die kranielle Meningeose präsentierte sich zum ersten Rezidivzeitpunkt different zum Primärtumor. Die extraneuralen Metastasen hatten bildcharakteristisch Ähnlichkeiten zum Primärtumor. Bei der Bewertung neuer intraparenchymaler Läsionen sollte immer der zeitliche Zusammenhang zur letzten Therapie und damit mögliche vorübergehende postradiologischen Veränderungen berücksichtigt werden.
Letztlich ist das pädiatrische Ependymom und Ependymomrezidiv ein komplexes und immer noch unvollständiges erfasstes Krankheitsbild. Durch umfangreichere Studien und die Zusammenführung dieser Ergebnisse könnte schlussendlich die Komplexität des Krankheitsbildes und somit die Therapieoptionen verbessert werden. Durch unsere Studie gelang einerseits die Beschreibung und der Vergleich des primären Ependymoms bezüglich supra- und infratentorieller Lokalisation und andererseits gelang eine neuroradiologische Beschreibung von Ependymomrezidiven im Vergleich zum primären Ependymom, wodurch in Zukunft die Nachsorge der Ependymomrezidive und die Therapieoptionen optimiert werden könnten.
Ziel der vorliegenden Studie war es, verschiedene kommerzielle Anbieter für KI-gestützte FRS-Analysen hinsichtlich ihrer Genauigkeit mit einem menschlichen Goldstandard zu vergleichen.
Auf 50 FRS wurden durch zwölf erfahrene Untersucher 15 Landmarken identifiziert, auf deren Basis neun relevante Parameter vermessen wurden. Der Medianwert dieser zwölf Auswertungen wurde für jeden Parameter auf jedem FRS als Goldstandard definiert und als Referenz für die Vergleiche mit vier verschiedenen kommerziellen KI-Anbietern (DentaliQ.ortho, WebCeph, AudaxCeph, CephX) festgelegt. Die statistische Auswertung erfolgte mittels ANOVA mit Messwiederholung, paarweiser Vergleiche mittels Post-hoc-Test und Bland-Altman-Plots.
DentaliQ.ortho zeigte für alle neun untersuchten Parameter keinen statistisch signifikanten Unterschied zum menschlichen Goldstandard und es konnte insgesamt von einer hohen Genauigkeit der Auswertungen ausgegangen werden. Auch für WebCeph war kein statistisch signifikanter Unterschied zum menschlichen Goldstandard zu verzeichnen. Allerdings war die Präzision im Vergleich zu den anderen Anbietern für alle Parameter am geringsten und der proportionale Fehler bei nahezu allen Parametern am höchsten. AudaxCeph wies für sieben Parameter statistisch signifikante Unterschiede zum menschlichen Goldstandard auf. Für CephX wurden für fünf Parameter statistisch signifikante Unterschiede zum menschlichen Goldstandard ermittelt. Insbesondere für die dentale Analyse war für alle untersuchten kommerziellen KI-Anbieter eine vergleichsweise niedrigere Genauigkeit zu verzeichnen.
Die Ergebnisse zeigen, dass noch deutliche Qualitätsunterschiede zwischen den kommerziellen KI-Anbietern für die vollständig automatisierte FRS-Analyse bestehen. Vor dem Hintergrund der Zeitersparnis und Qualitätssicherung sind KI zwar vielversprechend, sollten aber zum aktuellen Zeitpunkt nur unter Aufsicht durch menschliche Experten zum Einsatz kommen.
Even though the international combat against Neglected Tropical Diseases such as schistosomiasis or soil-transmitted helminthiases depends on reliable therapeutics, anthelminthic pharmacovigilance has been neglected on many national African drug markets. Therefore, quality and composition of 88 different batches of Albendazole, Mebendazole and Praziquantel locally collected from randomly selected facilities in Western Burkina Faso, Southeast Côte d’Ivoire, Southwest Ghana and Northwest Tanzania were analysed.
Visual examination of both packaging and samples was performed according to the WHO ‘Be Aware’ tool. Products were then screened with the GPHF Minilab, consisting of tests of mass uniformity, disintegration times and thin-layer chromatography (TLC). Confirmatory tests were performed according to international pharmacopoeiae, applying assays for dissolution profiles and high-performance liquid chromatography (HPLC).
Despite minor irregularities, appearance of the products did not hint at falsified medicines. However, 19.6 % of the brands collected in Ghana and Tanzania were not officially licensed for sale. Mass uniformity was confirmed in 53 out of 58 brands of tablets. 41 out of 56 products passed disintegration times; 10 out of the 15 failing products did not disintegrate at all.
TLC results did not reveal any falsifications or pronounced dosing errors. HPLC findings confirmed the TLC results despite shifted specification limits: ten of the 83 tested batches contained less than 90 %, none more than 110 % label claim. However, no more than 46.3 % (31 / 67) of the tablet batches assayed passed the respective criteria for dissolution.
In the four study countries, no falsified anthelminthic medicine was encountered. The active pharmaceutical ingredient was not found to either exceed or distinctively fall below specification limits. Galenic characteristics as most critical criteria however, especially dissolution profiles, revealed substantial deficits.
Das adrenokortikale Karzinom (ACC) ist eine seltene Tumorerkrankung der Nebennierenrinde. Die Prognose ist im Allgemeinen ungünstig und vom Tumorstadium sowie von weiteren tumor- und patientenspezifischen Faktoren abhängig. Die chirurgische Komplettresektion stellt das bisher einzige kurative Behandlungsverfahren dar.
Dabei gibt es bisher für sonstige Lokaltherapien beim fortgeschrittenen bzw. rezidivierten ACC kaum umfangreiche Daten, welche die entsprechende lokale Wirksamkeit belegen. Neben der Operation stellt die Strahlentherapie eine bisher effektive Therapieoption bei verschiedenen anderen Tumorerkrankungen hinsichtlich Tumorkontrolle, Verträglichkeit und Zugänglichkeit dar. Allerdings ist diese Option in der Behandlung des fortgeschrittenen ACC als Lokaltherapie bislang nicht mit zufriedenstellenden Datensätzen umfänglich untersucht.
Ziel dieser Studie war es, anhand einer retrospektiven Datenanalyse aus dem European Network for the Study of Adrenal Tumours (ENSAT) den Stellenwert der Strahlentherapie als Lokaltherapie beim fortgeschrittenen bzw. rezidivierten ACC zu untersuchen. Es wurden insgesamt 132 Fälle hinsichtlich strahlentherapeutischer Dosis, Lokalkontrolle, progressionsfreiem Überleben, Gesamtüberleben, objektivem Ansprechen, Verträglichkeit und Risikofaktoren untersucht.
Hierbei konnte gezeigt werden, dass die Anwendung einer hohen biologischen Effektivdosis mit einer verbesserten lokalen Tumorkontrolle einhergeht. Insgesamt zeigte sich eine gute Verträglichkeit der strahlentherapeutischen Behandlung. Die Ergebnisse dieser Arbeit legen nahe, dass wahrscheinlich weitere Risikofaktoren mit Rezidiven dieser Tumorart einhergehen, allerdings weitere Untersuchungen (z.B. randomisierte prospektive Studien) erfordern. Letztendlich stellt diese Arbeit auch die angewandten Dosis- und Fraktionierungskonzepte der vergangenen Jahrzente bei der Behandlung des ACC dar.
Postoperative pulmonale Komplikationen (PPC) stellen den Hauptgrund für erhöhte Morbidität und Mortalität sowie eine längere stationäre Liegedauer nach chirurgischen Eingriffen dar. Die Elektrische Impedanztomographie (EIT) ermöglicht als strahlungsfreie Methode die bettseitige Visualisierung der regionalen pulmonalen Ventilation in einem thorakalen Querschnittsbereich über den zeitlichen Verlauf.
Die Hauptfragestellung dieser Studie war die perioperativen Veränderungen der regionalen pulmonalen Ventilation bei spontanatmenden Patienten nach abdominalchirurgischen Eingriffen in Allgemeinnarkose bis in die späte postoperative Phase zu untersuchen. Zusätzlich untersuchten wir die Lungenfunktion mittels Spirometrie. Wir nahmen eine Verschiebung der pulmonalen Ventilation in dorso-ventraler Richtung an, sowie eine postoperativ reduzierte Vitalkapazität, z.B. durch Atelektasen oder Pleuraergüsse.
In die prospektive Observationsstudie wurden 36 erwachsene Patienten eingeschlossen, die sich einem elektiven abdominalchirurgischen Eingriff unter Allgemeinanästhesie unterzogen und ein mittleres Risiko gemäß ARISCAT Score für die Entwicklung von PPC aufwiesen. Präoperativ, sowie am 1. und 3. postoperativen Tag erfolgte die Untersuchung der pulmonalen Ventilation mittels EIT in Spontanatmung, Errechnung des Center of Ventilation (COV), sowie eine Lungenfunktionsprüfung mittels Spirometrie.
Nach abdominalchirurgischen Operationen kam es zu einer statistisch signifikanten und bis zum 3. postoperativen Tag anhaltenden Verschiebung der pulmonalen Ventilation nach ventral (COVy präop. 16,5; 1. Tag postop. 17,8; 3. Tag postop. 17,4). Zudem zeigte sich eine anhaltend reduzierte Forcierten Vitalkapazität in % vom Sollwert (FVC%Soll): präop. 93%; 1. Tag postop. 58%; 3. Tag postop. 64%. Am 3. postoperativen Tag bestand unter forcierter Atmung eine negative Assoziation zwischen der Änderung des COVy und der Änderung der FVC%Soll. PPC traten bei 10 Patienten in Form von respiratorischer Insuffizienz, Atelektase und Pleuraerguss auf. Bei diesen Patienten zeigte die EIT keine komplikationsspezifischen Bilder.
Abdominalchirurgische Operationen hatten hat einen relevanten Einfluss auf die postoperative regionale Lungenventilation und somit auf die Entstehung von PPC. Die EIT hilft die Entstehung von PPC besser zu verstehen und Strategien zur Vermeidung solcher im klinischen Alltag zu implementieren.
Ein Hilfsangebot für die, die immer schon alle die interessanten Werke der neulateinischen Epik aus Italien lesen wollten, die heute so bequem im Internet stehen, aber nie die Zeit dafür fanden: Rund 50 wenig bekannte Epen aus fünf Jahrhunderten werden in griffiger Zusammenfassung des Inhalts geboten, mit grundlegenden Verständnishilfen und Hinweisen auf die besonders gelungenen wie auch auf weniger geglückte Stellen.
Die Darstellung wird hier in zweiter, korrigierter und ergänzter Auflage vorgelegt.
Die Sammlung erweitert und ergänzt die bereits gedruckt erschienene Zusammenstellung „Ludwig Braun, Pedisequa Camenae. Zur Begleitung durch kaum bekannte Meisterwerke der neulateinischen Epik Italiens. Noctes Neolatinae 38, Hildesheim/Zürich/New York 2020.“
Die Dissertation befasst sich mit der Reaktivität von 1,2-Bis(dichlorboryl)benzol. Im ersten Kapitel wird auf die Problematik bei dessen Synthese eingegangen. Der zweite Teil der Arbeit befasst sich mit der Bildung von entsprechenden Boran-Addukten mit verschiedenen Lewis-Basen. Das dritte Kapitel beschreibt die Synthese eines neuartigen, vollständig ungesättigten 1,2-Diboretdiradikals, welches durch die schrittweise Reduktion des 1,2-[(CAAC)BCl2]2-Benzols erhalten wurde. Darüber hinaus konnte bei dieser schrittweisen Reduktion ebenfalls das einfache Borylradikal, das nicht-cyclische Diradikal und das dianionische gespannte C2B2-Ringsystem erhalten werden. Anfängliche Reaktivitätsstudien zum 1,2-Diboretdiradikal zeigen zudem, dass die B-B-Bindung durch Umsetzung mit Kohlenstoffmonoxid gespalten und so ein Bisborylen dargestellt werden kann. Im vierten Kapitel konnte das 1,2-Bis(dichlorboryl)benzol durch Transmetallierungsreaktionen zu verschiedenen, sich in ihren Eigenschaften stark unterscheidenden, Verbindungen umgesetzt werden. So konnte das fluoreszierende ortho-phenylenverbrückte Bis-9-Borafluoren erhalten werden, aus welchem durch Wärmezufuhr das ebenfalls fluoreszierendes diboraanthracenartige Umlagerungsprodukt gewonnen werden konnte. Beide Verbindungen wurden auf ihre photophysikalischen und elektrochemischen Eigenschaften untersucht. Weiterhin konnten polycyclische Boracyclen mit C10B2-Gerüst erhalten werden, bei welchen instantan die selektive Bildung von zwei chiralen Zentren über eine Vielzahl an B-C-Bindungsbrüchen und -knüpfungen beobachtet wurde. Zuletzt konnte ein thermisch empfindliches, potentiell explosives Azid-verbrücktes Azidoboran dargestellt werden, bei welchem eine Staudinger-artige Reaktivität beobachtet werden konnte.
Die idiopathische Lungenfibrose (IPF) stellt eine chronische Krankheit mit einer schlechten Prognose dar. Die Erkrankung zeichnet sich durch ein dysfunktionales Alveolarepithel, die Formation von α-smooth muscle actin (α-SMA)-positiven Myofibroblasten, eine starke Kollagendeposition sowie eine fehlgeleitete Inflammation aus. In der Vermittlung dieser pro-fibrotischen Effekte spielt das Zytokin transforming growth factor β (TGF-β) eine Schlüsselrolle. Aufgrund des tödlichen Verlaufs der IPF und der limitierten Therapieoptionen ist die Entdeckung neuer Behandlungsansätze erforderlich.
Der NO/cGMP-Signalweg ist in der Modulation grundlegender physiologischer Vorgänge wie der Blutdruckregulation und der Peristaltik involviert. Hierbei spielt die NO-sensitive Guanylyl-Cyclase (NO-GC) als NO-Rezeptor eine fundamentale Rolle. In der Lunge wird die NO-GC in glatten Muskelzellen und Perizyten exprimiert. Während das Enzym in glatten Muskelzellen die Relaxation der glatten Muskulatur vermittelt, reguliert die NO-GC in Perizyten die Angiogenese, die Kapillardurchlässigkeit und den Blutfluss. Neben den physiologischen Aufgaben wurden anti-fibrotische sowie anti-inflammatorische Effekte der NO-GC in Herz, Leber, Niere und Haut beschrieben.
Daher wurde im Rahmen dieser Arbeit die NO-GC auf eine anti-fibrotische und anti-inflammatorische Bedeutung in der Lungenfibrose der Maus überprüft. Hierzu wurden Wildtyp- (WT) und globale NO-GC-Knockout-Mäuse (GCKO) untersucht. Die Fibrose wurde durch einmalige, orotracheale Bleomycin-Gabe induziert und zu unterschiedlichen Zeitpunkten (Tag 7 und 21) untersucht. Unbehandelte (Tag 0) Tiere dienten als Kontrolle. Im ersten Teil dieser Arbeit wurde die NO-GC auf eine anti-fibrotische Wirkung untersucht. Mittels Immunfluoreszenz wurde das Verhalten der α-SMA-positiven Myofibroblasten in den platelet-derived growth factor receptor β (PDGFRβ)-positiven fibrotischen Regionen untersucht. Der Kollagengehalt wurde mithilfe eines Hydroxyprolin-Kollagenassays ermittelt. Die untersuchten Fibrose-Kriterien waren in beiden Genotypen an Tag 21 stärker ausgeprägt als an Tag 7. An Tag 21 konnten im GCKO mehr α-SMA-positive Myofibroblasten, ausgeprägtere PDGFRβ-positive fibrotische Areale und ein höherer Kollagengehalt als im WT festgestellt werden. Zudem zeigten die GCKO-Tiere ein schlechteres Überleben als WT-Mäuse. Diese Ergebnisse wiesen auf eine überschießende fibrotische Antwort im GCKO und somit auf eine anti-fibrotische Wirkung der NO-GC in der Bleomycin-induzierten Lungenfibrose hin. Dass an Tag 21 die Fibrose im GCKO stärker ausfiel als im WT, konnte mit dem signifikant höheren TGF-β-Gehalt in der bronchoalveolären Lavageflüssigkeit (BALF) im GCKO erklärt werden. Das Fehlen der NO-GC im GCKO könnte zu einem Wegfall der Inhibierung der TGF-β-vermittelten, pro-fibrotischen Effekte durch die NO-GC führen. Weitere Studien sind erforderlich, um die Hypothese zu belegen und zugrundeliegende Mechanismen aufzuklären.
Die de novo Entstehung von Myofibroblasten, die maßgeblich an der Kollagensynthese beteiligt sind, stellt ein entscheidendes Fibrose-Merkmal dar. Umso bedeutender ist die Identifikation zweier Myofibroblasten-Subtypen, die sich in Lokalisation, NO-GC-Expression und Herkunft unterscheiden: (1) interstitielle, NO-GC-positive Myofibroblasten, die von Perizyten abstammen und Kollagen Typ I produzieren, und (2) intra-alveoläre, NO-GC-negative Myofibroblasten, deren Ursprung noch nicht abschließend geklärt ist. Die Anwesenheit beider Myofibroblasten-Typen konnte zu beiden untersuchten Zeitpunkten nach Bleomycin-Gabe bestätigt werden. Die NO-GC-Expression der Alveolarwand-ständigen Myofibroblasten, deren Abstammung von NO-GC-positiven Perizyten sowie deren dauerhafte Präsenz sprechen für eine relevante Rolle der NO-GC in der murinen Lungenfibrose. In weiteren Untersuchungen müssen die exakten Funktionen und spezifische Marker der Myofibroblasten-Subtypen identifiziert werden.
Im zweiten Teil dieser Arbeit wurde die NO-GC auf anti-inflammatorische Effekte in der Bleomycin-induzierten Lungenfibrose untersucht. Mittels HE-Färbung und Immunfluoreszenz wurden lymphozytäre Infiltrate an Tag 21 im GCKO festgestellt, was auf einen modulatorischen Einfluss der NO-GC auf das Immunsystem hindeutete. An Tag 21 wurden in der BALF von GCKO-Tieren signifikant mehr Gesamtimmunzellen, Lymphozyten und neutrophile Granulozyten als im WT gezählt, was auf eine starke Einwanderung von Immunzellen und somit auf eine ausgeprägte Entzündung in GCKO-Lungen hinwies. Folglich könnte die NO-GC eine anti-inflammatorische Rolle über die Regulation der Immigration von Immunzellen in der Bleomycin-induzierten Lungenfibrose spielen. In der Literatur werden pro- und anti-fibrotische Effekte der Immunzellen in der murinen Lungenfibrose diskutiert. Durch Korrelationsanalysen wurde ein positiver Zusammenhang zwischen der Gesamtimmunzellzahl und der TGF-β-Konzentration an Tag 21 festgestellt. In verschiedenen Studien wurde ein pro-fibrotischer Einfluss der Immunzellen über die Aktivierung/Sekretion von TGF-β beschrieben. Die Abwesenheit der NO-GC im GCKO könnte also über die verstärkte Immigration von Immunzellen in einem erhöhten TGF-β-Gehalt resultieren und so zu einer überschießenden fibrotischen Reaktion an Tag 21 führen. Auf welche Weise die NO-GC die Einwanderung der Immunzellen in der Bleomycin-induzierten Lungenfibrose beeinflusst, muss in weiteren Studien untersucht werden. Zusammenfassend deuten die Daten dieser Arbeit auf eine anti-inflammatorische und anti-fibrotische Rolle der NO-GC in der Lungenfibrose der Maus hin.
Within this thesis, three main approaches for the assessment and investigation of altered hemodynamics like wall shear stress, oscillatory shear index and the arterial pulse wave velocity in atherosclerosis development and progression were conducted:
1. The establishment of a fast method for the simultaneous assessment of 3D WSS and PWV in the complete murine aortic arch via high-resolution 4D-flow MRI
2. The utilization of serial in vivo measurements in atherosclerotic mouse models using high-resolution 4D-flow MRI, which were divided into studies describing altered hemodynamics in late and early atherosclerosis
3. The development of tissue-engineered artery models for the controllable application and variation of hemodynamic and biologic parameters, divided in native artery models and biofabricated artery models, aiming for the investigation of the relationship between atherogenesis and hemodynamics
Chapter 2 describes the establishment of a method for the simultaneous measurement of 3D WSS and PWV in the murine aortic arch at, using ultra high-field MRI at 17.6T [16], based on the previously published method for fast, self-navigated wall shear stress measurements in the murine aortic arch using radial 4D-phase contrast MRI at 17.6 T [4]. This work is based on the collective work of Dr. Patrick Winter, who developed the method and the author of this thesis, Kristina Andelovic, who performed the experiments and statistical analyses. As the method described in this chapter is basis for the following in vivo studies and undividable into the sub-parts of the contributors without losing important information, this chapter was not split into the single parts to provide fundamental information about the measurement and analysis methods and therefore better understandability for the following studies. The main challenge in this chapter was to overcome the issue of the need for a high spatial resolution to determine the velocity gradients at the vascular wall for the WSS quantification and a high temporal resolution for the assessment of the PWV without prolonging the acquisition time due to the need for two separate measurements. Moreover, for a full coverage of the hemodynamics in the murine aortic arch, a 3D measurement is needed, which was achieved by utilization of retrospective navigation and radial trajectories, enabling a highly flexible reconstruction framework to either reconstruct images at lower spatial resolution and higher frame rates for the acquisition of the PWV or higher spatial resolution and lower frame rates for the acquisition of the 3D WSS in a reasonable measurement time of only 35 minutes. This enabled the in vivo assessment of all relevant hemodynamic parameters related to atherosclerosis development and progression in one experimental session. This method was validated in healthy wild type and atherosclerotic Apoe-/- mice, indicating no differences in robustness between pathological and healthy mice.
The heterogeneous distribution of plaque development and arterial stiffening in atherosclerosis [10, 12], however, points out the importance of local PWV measurements. Therefore, future studies should focus on the 3D acquisition of the local PWV in the murine aortic arch based on the presented method, in order to enable spatially resolved correlations of local arterial stiffness with other hemodynamic parameters and plaque composition.
In Chapter 3, the previously established methods were used for the investigation of changing aortic hemodynamics during ageing and atherosclerosis in healthy wild type and atherosclerotic Apoe-/- mice using the previously established methods [4, 16] based on high-resolution 4D-flow MRI. In this work, serial measurements of healthy and atherosclerotic mice were conducted to track all changes in hemodynamics in the complete aortic arch over time. Moreover, spatially resolved 2D projection maps of WSS and OSI of the complete aortic arch were generated. This important feature allowed for the pixel-wise statistical analysis of inter- and intragroup hemodynamic changes over time and most importantly – at a glance. The study revealed converse differences of local hemodynamic profiles in healthy WT and atherosclerotic Apoe−/− mice, with decreasing longWSS and increasing OSI, while showing constant PWV in healthy mice and increasing longWSS and decreasing OSI, while showing increased PWV in diseased mice. Moreover, spatially resolved correlations between WSS, PWV, plaque and vessel wall characteristics were enabled, giving detailed insights into coherences between hemodynamics and plaque composition. Here, the circWSS was identified as a potential marker of plaque size and composition in advanced atherosclerosis. Moreover, correlations with PWV values identified the maximum radStrain could serve as a potential marker for vascular elasticity. This study demonstrated the feasibility and utility of high-resolution 4D flow MRI to spatially resolve, visualize and analyze statistical differences in all relevant hemodynamic parameters over time and between healthy and diseased mice, which could significantly improve our understanding of plaque progression towards vulnerability. In future studies the relation of vascular elasticity and radial strain should be further investigated and validated with local PWV measurements and CFD.
Moreover, the 2D histological datasets were not reflecting the 3D properties and regional characteristics of the atherosclerotic plaques. Therefore, future studies will include 3D plaque volume and composition analysis like morphological measurements with MRI or light-sheet microscopy to further improve the analysis of the relationship between hemodynamics and atherosclerosis.
Chapter 4 aimed at the description and investigation of hemodynamics in early stages of atherosclerosis. Moreover, this study included measurements of hemodynamics at baseline levels in healthy WT and atherosclerotic mouse models. Due to the lack of hemodynamic-related studies in Ldlr-/- mice, which are the most used mouse models in atherosclerosis research together with the Apoe-/- mouse model, this model was included in this study to describe changing hemodynamics in the aortic arch at baseline levels and during early atherosclerosis development and progression for the first time. In this study, distinct differences in aortic geometries of these mouse models at baseline levels were described for the first time, which result in significantly different flow- and WSS profiles in the Ldlr-/- mouse model. Further basal characterization of different parameters revealed only characteristic differences in lipid profiles, proving that the geometry is highly influencing the local WSS in these models. Most interestingly, calculation of the atherogenic index of plasma revealed a significantly higher risk in Ldlr-/- mice with ongoing atherosclerosis development, but significantly greater plaque areas in the aortic arch of Apoe-/- mice. Due to the given basal WSS and OSI profile in these two mouse models – two parameters highly influencing plaque development and progression – there is evidence that the regional plaque development differs between these mouse models during very early atherogenesis.
Therefore, future studies should focus on the spatiotemporal evaluation of plaque development and composition in the three defined aortic regions using morphological measurements with MRI or 3D histological analyses like LSFM. Moreover, this study offers an excellent basis for future studies incorporating CFD simulations, analyzing the different measured parameter combinations (e.g., aortic geometry of the Ldlr-/- mouse with the lipid profile of the Apoe-/- mouse), simulating the resulting plaque development and composition. This could help to understand the complex interplay between altered hemodynamics, serum lipids and atherosclerosis and significantly improve our basic understanding of key factors initiating atherosclerosis development.
Chapter 5 describes the establishment of a tissue-engineered artery model, which is based on native, decellularized porcine carotid artery scaffolds, cultured in a MRI-suitable bioreactor-system [23] for the investigation of hemodynamic-related atherosclerosis development in a controllable manner, using the previously established methods for WSS and PWV assessment [4, 16]. This in vitro artery model aimed for the reduction of animal experiments, while simultaneously offering a simplified, but completely controllable physical and biological environment. For this, a very fast and gentle decellularization protocol was established in a first step, which resulted in porcine carotid artery scaffolds showing complete acellularity while maintaining the extracellular matrix composition, overall ultrastructure and mechanical strength of native arteries. Moreover, a good cellular adhesion and proliferation was achieved, which was evaluated with isolated human blood outgrowth endothelial cells. Most importantly, an MRI-suitable artery chamber was designed for the simultaneous cultivation and assessment of high-resolution 4D hemodynamics in the described artery models. Using high-resolution 4D-flow MRI, the bioreactor system was proven to be suitable to quantify the volume flow, the two components of the WSS and the radStrain as well as the PWV in artery models, with obtained values being comparable to values found in literature for in vivo measurements. Moreover, the identification of first atherosclerotic processes like intimal thickening is achievable by three-dimensional assessment of the vessel wall morphology in the in vitro models. However, one limitation is the lack of a medial smooth muscle cell layer due to the dense ECM. Here, the utilization of the laser-cutting technology for the generation of holes and / or pits on a microscale, eventually enabling seeding of the media with SMCs showed promising results in a first try and should be further investigated in future studies. Therefore, the proposed artery model possesses all relevant components for the extension to an atherosclerosis model which may pave the way towards a significant improvement of our understanding of the key mechanisms in atherogenesis.
Chapter 6 describes the development of an easy-to-prepare, low cost and fully customizable artery model based on biomaterials. Here, thermoresponsive sacrificial scaffolds, processed with the technique of MEW were used for the creation of variable, biomimetic shapes to mimic the geometric properties of the aortic arch, consisting of both, bifurcations and curvatures. After embedding the sacrificial scaffold into a gelatin-hydrogel containing SMCs, it was crosslinked with bacterial transglutaminase before dissolution and flushing of the sacrificial scaffold. The hereby generated channel was subsequently seeded with ECs, resulting in an easy-to-prepare, fast and low-cost artery model. In contrast to the native artery model, this model is therefore more variable in size and shape and offers the possibility to include smooth muscle cells from the beginning. Moreover, a custom-built and highly adaptable perfusion chamber was designed specifically for the scaffold structure, which enabled a one-step creation and simultaneously offering the possibility for dynamic cultivation of the artery models, making it an excellent basis for the development of in vitro disease test systems for e.g., flow-related atherosclerosis research. Due to time constraints, the extension to an atherosclerosis model could not be achieved within the scope of this thesis. Therefore, future studies will focus on the development and validation of an in vitro atherosclerosis model based on the proposed bi- and three-layered artery models.
In conclusion, this thesis paved the way for a fast acquisition and detailed analyses of changing hemodynamics during atherosclerosis development and progression, including spatially resolved analyses of all relevant hemodynamic parameters over time and in between different groups. Moreover, to reduce animal experiments, while gaining control over various parameters influencing atherosclerosis development, promising artery models were established, which have the potential to serve as a new platform for basic atherosclerosis research.
Drug Discovery based on Oxidative Stress and HDAC6 for Treatment of Neurodegenerative Diseases
(2024)
Most antioxidants reported so far only achieved limited success in AD clinical trials. Growing evidences suggest that merely targeting oxidative stress will not be sufficient to fight AD. While multi-target directed ligands could synergistically modulate different steps in the neurodegenerative process, offering a promising potential for treatment of this complex disease.
Fifteen target compounds have been designed by merging melatonin and ferulic acid into the cap group of a tertiary amide HDAC6 inhibitor. Compound 10b was screened as the best hybrid molecule exhibit potent HDAC6 inhibition and potent antioxidant capacity. Compound 10b also alleviated LPS-induced microglia inflammation and led to a switch from neurotoxic M1 to the neuroprotective M2 microglial phenotype. Moreover, compound 10b show pronounced attenuation of spatial working memory and long-term memory damage in an in vivo AD mouse model. Compound 10b can be a potentially effective drug candidate for treatment of AD and its druggability worth to be further studied.
We have designed ten novel neuroprotectants by hybridizing with several common antioxidants, including ferulic acid, melatonin, lipoic acid, and trolox. The trolox hybrid compound exhibited the most potent neuroprotective effects in multiple neuroprotection assays. Besides, we identified the synergistic effects between trolox and vitamin K derivative, and our trolox hybrid compound showed comparable neuroprotection with the mixture of trolox and vitamin K derivative.
We have designed and synthesized 24 quinone derivatives based on five kinds of different quinones including ubiquinone, 2,3,5-trimethyl-1,4-benzoquinone, memoquin, thymoquinone, and anthraquinone. Trimethylbenzoquinone and thymoquinone derivatives showed more potent neuroprotection than other quinones in oxytosis assay. Therefore, trimethylbenzoquinone and thymoquinone derivatives can be used as lead compounds for further mechanism study and drug discovery for treatment of neurodegenerative disease.
We designed a series of photoswitchable HDAC inhibitors, which could be effective molecular tools due to the high spatial and temporal resolution. In total 23 target compounds were synthesized and photophysicochemically characterized. Azoquinoline-based compounds possess more thermally stable cis-isomers in buffer solution, which were further tested in enzyme-based HDAC inhibition assay. However, none of those tested compounds show significant differences in activities between trans-isomers and corresponding cis-isomers.
Ecophysiological adaptations of the cuticular water permeability within the Solanaceae family
(2024)
The cuticle, a complex lipidic layer synthesized by epidermal cells, covers and protects primary organs of all land plants. Its main function is to avoid plant desiccation by limiting non-stomatal water loss. The cuticular properties vary widely among plant species. So far, most of the cuticle-related studies have focused on a limited number of species, and studies addressing phylogenetically related plant species are rare. Moreover, comparative studies among organs from the same plant species are still scarce.
Thus, this study focus on organ-specificities of the cuticle within and between plant species of the Solanaceae family. Twenty-seven plant species of ten genera, including cultivated and non- cultivated species, were investigated to identify potential cuticular similarities. Structural, chemical and functional traits of fully expanded leaves, inflated fruiting calyces, and ripe fruits were analyzed.
The surface morphology was investigated by scanning electron microscopy. Leaves were mainly amphistomatic and covered by an epicuticular wax film. The diversity and distribution of trichomes varied among species. Only the leaves of S. grandiflora were glabrous. Plant species of the Leptostemonum subgenus had numerous prickles and non-glandular stellate trichomes. Fruits were stomata-free, except for S. muricatum, and a wax film covered their surface. Last, lenticel- like structures and remaining scars of broken trichomes were found on the surface of some Solanum fruits.
Cuticular water permeability was used as indicators of the cuticular transpiration barrier efficiency. The water permeability differed among plant species, organs and fruit types with values ranging up to one hundred-fold. The minimum leaf conductance ranged from 0.35 × 10-5 m s-1 in S. grandiflora to 31.54 × 10-5 m s-1 in S. muricatum. Cuticular permeability of fruits ranged from 0.64 × 10-5 m s-1 in S. dulcamara (fleshy berry) to 34.98 × 10-5 m s-1 in N. tabacum (capsule). Generally, the cuticular water loss of dry fruits was about to 5-fold higher than that of fleshy fruits.
Interestingly, comparisons between cultivated and non-cultivated species showed that wild species have the most efficient cuticular transpiration barrier in leaves and fruits. The average permeability of leaves and fruits of wild plant species was up to three-fold lower in comparison to the cultivated ones. Moreover, ripe fruits of P. ixocarpa and P. peruviana showed two-times lower cuticular transpiration when enclosed by the inflated fruiting calyx.
The cuticular chemical composition was examined using gas chromatography. Very-long-chain aliphatic compounds primarily composed the cuticular waxes, being mostly dominated by n- alkanes (up to 80% of the total wax load). Primary alkanols, alkanoic acids, alkyl esters and branched iso- and anteiso-alkanes were also frequently found. Although in minor amounts, sterols, pentacyclic triterpenoids, phenylmethyl esters, coumaric acid esters, and tocopherols were identified in the cuticular waxes. Cuticular wax coverages highly varied in solanaceous (62- fold variation). The cuticular wax load of fruits ranged from 0.55 μg cm−2 (Nicandra physalodes) to 33.99 μg cm−2 (S. pennellii), whereas the wax amount of leaves varied from 0.90 μg cm−2 (N. physalodes) to 28.42 μg cm−2 (S. burchellii). Finally, the wax load of inflated fruiting calyces ranged from 0.56 μg cm−2 in P. peruviana to 2.00 μg cm−2 in N. physalodes.
For the first time, a comparative study on the efficiency of the cuticular transpiration barrier in different plant organs of closely related plant species was conducted. Altogether, the cuticular chemical variability found in solanaceous species highlight species-, and organ-specific wax biosynthesis. These chemical variabilities might relate to the waterproofing properties of the plant cuticle, thereby influencing leaf and fruit performances. Additionally, the high cuticular water permeabilities of cultivated plant species suggest a potential existence of a trade-off between fruit organoleptic properties and the efficiency of the cuticular transpiration barrier. Last, the high cuticular water loss of the solanaceous dry fruits might be a physiological adaptation favouring seed dispersion.
In aqueous environment, hydrophobic interactions play an important role for DNA. The introduction of modifications based on hydrophobic aromatic moieties offers additional ways for controlling recognition and reactivity of functional groups in DNA. Modifications are introduced through an artificial backbone or in the form of an extension of the nucleobases, resulting in additional properties of the DNA.
This dissertation focuses on the use of hydrophobic units for the functionalization of DNA.
In the first part of the work, the tolane (i. e. diphenylacetylene) motif was used in combination with the acyclic backbone of GNA and BuNA to generate recognition units in the DNA context. Fluorination of the aromatic rings in the tolane moiety provided the basis for a supramolecular language based on arene-fluoroarene interactions. The specific recognition was investigated by thermodynamic, kinetic and NMR spectroscopic methods.
In the second part of the work, deoxyuridine derivatives with a hydrophobic aromatic modification were prepared and incorporated into DNA duplexes. The irradiation with UV light led to a [2+2] cycloaddition reaction between two modified nucleosides in the DNA. This reaction product was structurally characterized and the reaction was used in various biochemical and nanotechnological DNA applications.
Dieses fünfte Jean Monnet Paper fügt alle 36 mainEUropa-Blogs, die zwischen 2017 und 2021 an der mit einem Jean Monnet Lehrstuhl ausgezeichneten Professur für Europaforschung und Internationale Beziehungen der Universität Würzburg verfasst wurden, zu einer einheitlichen Publikation zusammen. Die mainEUropa-Blogs wollten über ausgewählte Aspekte der EU-Politik aktuell, knapp und leicht verständlich informieren; damit haben sie dem EU-Geschehen der Jahre 2017 bis 2021 aus jeweils aktuellen Anlässen den Puls genommen und zu einem besseren Verständnis der EU-Politik- und Entscheidungsprozesse beigetragen.
Die Blog-Themen sind breit gefächert und bilden somit ausgewählte Ereignisse und Weichenstellungen aus der jüngeren Integrationsgeschichte ab. Die Themen reichen über klimapolitische Beschlüsse, das Ringen um den Erhalt bzw. die Wiederherstellung der Rechtstaatlichkeit in einigen EU-Mitgliedstaaten, das Endlos-Drama des Brexits, wichtige Wahlen in der EU und ausgewählten Mitgliedstaaten bis hin zu neuen Entwicklungen in der EU-Außen-, Sicherheits- und Verteidigungspolitik sowie zu den überraschend zupackenden Antworten der EU auf die Covid-19-Pandemie. Ein Blick auf die europapolitische Agenda der im Dezember 2021 angetretenen rot-grün-gelben Ampel-Bundesregierung beschließt die Reihe. Denn 2021 endete auch das die mainEUropa-Blogs tragende Jean Monnet Projekt, so dass das vorliegende fünfte Jean Monnet Paper auch das letzte sein wird.
Biofabrication technologies must address numerous parameters and conditions to reconstruct tissue complexity in vitro. A critical challenge is vascularization, especially for large constructs exceeding diffusion limits. This requires the creation of artificial vascular structures, a task demanding the convergence and integration of multiple engineering approaches. This doctoral dissertation aims to achieve two primary objectives: firstly, to implement and refine engineering methods for creating artificial microvascular structures using Melt Electrowriting (MEW)-assisted sacrificial templating, and secondly, to deepen the understanding of the critical factors influencing the printability of bioink formulations in 3D extrusion bioprinting.
In the first part of this dissertation, two innovative sacrificial templating techniques using MEW are explored. Utilizing a carbohydrate glass as a fugitive material, a pioneering advancement in the processing of sugars with MEW with a resolution under 100 microns was made. Furthermore, by introducing the “print-and-fuse” strategy as a groundbreaking method, biomimetic branching microchannels embedded in hydrogel matrices were fabricated, which can then be endothelialized to mirror in vivo vascular conditions.
The second part of the dissertation explores extrusion bioprinting. By introducing a simple binary bioink formulation, the correlation between physical properties and printability was showcased. In the next step, employing state-of-the-art machine-learning approaches revealed a deeper understanding of the correlations between bioink properties and printability in an extended library of hydrogel formulations.
This dissertation offers in-depth insights into two key biofabrication technologies. Future work could merge these into hybrid methods for the fabrication of vascularized constructs, combining MEW's precision with fine-tuned bioink properties in automated extrusion bioprinting.
Adoptive immunotherapy using chimeric antigen receptor (CAR)-modified T cells is an effective treatment for hematological malignancies that are refractory to conventional chemotherapy. To address a wider variety of cancer entities, there is a need to identify and characterize additional target antigens for CAR-T cell therapy. The two members of the receptor tyrosine kinase-like orphan receptor family, ROR1 and ROR2, have been found to be overexpressed on cancer cells and to correlate with aggressive cancer phenotypes. Recently, ROR1-specific CAR-T cells have entered testing in phase I clinical trials, encouraging us to assess the suitability of ROR2 as a novel target for CAR-T cell therapy. To study the therapeutic potential of targeting ROR2 in solid and hematological malignancies, we selected two representative cancer entities with high unmet medical need: renal cell carcinoma and multiple myeloma.
Our data show that ROR2 is commonly expressed on primary samples and cell lines of clear cell renal cell carcinoma and multiple myeloma. To study the efficacy of ROR2-specific CAR T cell therapy, we designed two CAR constructs with 10-fold binding affinity differences for the same epitope of ROR2. We found both cell products to exhibit antigen-specific anti-tumor reactivity in vitro, including tumor cell lysis, secretion of the effector cytokines interleukin-2 (IL-2) and interferon-gamma (IFNγ), and T cell proliferation. In vivo studies revealed ROR2 specific CAR-T cells to confer durable responses, significant survival benefits and long-term persistence of CAR-expressing T cells. Overall, there was a trend towards more potent anti-tumor efficacy upon treatment with T cells that expressed the CAR with higher affinity for ROR2, both in vitro and in vivo.
We performed a preclinical safety and toxicology assessment comprising analyses of ROR2 expression in healthy human and murine tissues, cross-reactivity, and adoptive T cell transfer in immunodeficient mice. We found ROR2 expression to be conserved in mice, and low-level expression was detectable in the male and female reproductive system as well as parts of the gastrointestinal tract. CAR-T cells targeting human ROR2 were found to elicit similarly potent reactivity upon recognition of murine ROR2. In vivo analyses showed transient tissue-specific enrichment and activation of ROR2-specific CAR-T cells in organs with high blood circulation, such as lung, liver, or spleen, without evidence for clinical toxicity or tissue damage as determined by histological analyses.
Furthermore, we humanized the CAR binding domain of ROR2-specific CAR-T cells to mitigate the risk of adverse immune reactions and concomitant CAR-T cell rejection. Functional analyses confirmed that humanized CARs retained their specificity and functionality against ROR2-positive tumor cells in vitro.
In summary, we show that ROR2 is a prevalent target in RCC and MM, which can be addressed effectively with ROR2-specific CAR-T cells in preclinical models. Our preliminary toxicity studies suggest a favorable safety profile for ROR2-specific CAR-T cells. These findings support the potential to develop ROR2-specific CAR-T cells clinically to obtain cell products with broad utility.
Plasmonic nanostructures are considered promising candidates for essential components of integrated quantum technologies because of their ability to efficiently localize broad-band electromagnetic fields on the nanoscale. The resulting local near field can be understood as a spatial superposition of spectrally different plasmon-polariton modes due to the spectrally broad optical excitation, and thus can be described as a classical wave packet. Since plasmon polaritons, in turn, can transmit and receive non-classical light states, the exciting question arises to what extent they have to be described as quantum mechanical wave packets, i.e. as a superposition of different quantum states.
But how to probe, characterize and eventually manipulate the quantum state of such plasmon polaritons? Up to now, probing at room temperatures relied completely on analyzing quantum optical properties of the corresponding in-going and out-going far-field photon modes. However, these methods so far only allow a rather indirect investigation of the plasmon-polariton quantum state by means of transfer into photons. Moreover, these indirect methods lack spatial resolution and therefore do not provide on-site access to the plasmon-polariton quantum state. However, since the spectroscopic method of coherent two-dimensional (2D) nanoscopy offers the capability to follow the plasmon-
polariton quantum state both in Hilbert space and in space and time domain a complete characterization of the plasmon polariton is possible.
In this thesis a versatile coherent 2D nanoscopy setup is presented combining spectral tunability and femtosecond time resolution with spatial resolution on the nanometer scale due to the detection of optically excited nonlinear emitted electrons via photoemission electron microscopy (PEEM). Optical excitation by amplitude- and phase-shaped, systematically-modified and interferometric-stable multipulse sequences is realized, and characterized via Fourier-transform spectral interferometry (FTSI). This linear technique enables efficient data acquisition in parallel to a simultaneously performed experiment. The full electric-field reconstruction of every generated multipulse sequence is used to analyze the effect of non-ideal pulse sequences on the two-dimensional spectral data of population-based multidimensional spectroscopy methods like, e.g., the coherent 2D nanoscopy applied in this thesis. Investigation of the spatially-resolved nonlinear electron emission yield from plasmonic gold nanoresonators by coherent 2D nanoscopy requires a quasi-particle treatment of the addressed plasmon-polariton mode and development of a quantum model to adequately describe the plasmon-assisted multi-quantum electron emission from nanostructures. Good agreement between simulated and experimental data enables to connect certain spectral features to superpositions of non-adjacent plasmon-polariton quantum states, i.e, non-adjacent occupation-number states of the underlying quantized, harmonic oscillator, thus direct probing of the plasmon-polariton quantum wave packet at the location of the nanostructure.
This is a necessary step to locally control and manipulate the plasmon-polariton quantum state and thus of general interest for the realization of nanoscale quantum optical devices.
Arrhythmogene Kardiomyopathie (ACM) ist eine genetische Herzerkrankung, die durch Herzinsuffizienz, ventrikuläre Arrhythmien und plötzlichen Herztod gekennzeichnet ist. Mutationen in desmosomalen Proteinen der Zelladhäsion, wie Plakophilin 2 (PKP2) und Plakoglobin (PG), sind die häufigste Ursache der familiären ACM. Wie gestörte Zelladhäsion zum ACM-Phänotyp führt, ist jedoch nur teilweise geklärt. Potentielle Mechanismen sind eine gestörte Kalzium-(Ca2+)-Homöostase, mitochondrialer oxidativer Stress und metabolische Störungen. Ziel dieser Studie ist es, die mitochondriale Energetik und die Ca2+ -Homöostase in kardio-restriktiven PKP2-Knockout-Mäusen (KO) im Alter von 4, 8 und 12 Wochen sowie in PG-Knockout- Mäusen im Alter von 6 Wochen zu untersuchen. Vier Wochen alte PKP2-KO-Mäuse zeigten frühe Anzeichen von ACM, während alle anderen Altersgruppen typische Kennzeichen von ACM rekapitulierten. Kontraktilität, die damit verbundenen Ca2+ - Transienten, der Redoxstatus und das mitochondriale Membranpotenzial (ΔΨm) isolierter Kardiomyozyten wurden mit einem IonOptix-System bei elektrischer und β- adrenerger Stimulation untersucht. Alle desmosomalen KO-Kardiomyozyten zeigten eine verringerte diastolische Sarkomerlänge, was auf eine diastolische Dysfunktion hinwies. In allen PKP2 KO Kardiomyozyten lag außerdem ein erhöhter intrazellulärer Ca2+ -Spiegel vor, während in den PG KO-Kardiomyozyten das intrazellulärer Ca2+ unverändert war. PKP2 KO- und PG KO-Kardiomyozyten wiesen keine Ca2+ - Sensibilisierung der Myofilamente auf. Zur weiteren Bewertung der mitochondrialen Funktion wurde eine hochauflösende Respirometrie in isolierten Herzmitochondrien bei gleichzeitiger Überwachung von ΔΨm in PKP2 KO und PG KO Mäusen durchgeführt, welche in allen Versuchs- und Kontrollgruppen vergleichbar war. Im Verlauf der Versuche blieb der Redoxstatus stabil und es konnte kein Exzess reaktiver Sauerstoffspezies (ROS) festgestellt werden. Daraus konnte gefolgert werden, dass weder PKP2 KO noch PG KO-Mäuse eine beeinträchtigte mitochondriale Atmung aufwiesen. Diese Studie zeigt, dass isolierte PKP2 KO- oder PG KO-Kardiomyozyten EC-Kopplungsdefekte ohne mitochondriale Dysfunktion aufwiesen. Eine mitochondriale Dysfunktion konnte als treibender Faktor für die Progression des ACM- Phänotyps in den vorgestellten Mausmodellen ausgeschlossen werden. Weitere Studien sind erforderlich, um die mitochondriale Funktion im Zusammenhang mit ACM zu entschlüsseln.
Biological systems are in dynamic interaction. Many responses reside in the core concepts of biological systems interplay (competition and cooperation). In infection situation, the competition between a bacterial system and a host is shaped by many stressors at spatial and temporal determinants. Reactive chemical species are universal stressors against all biological systems since they potentially damage the basic requirements of these systems (nucleic acids, proteins, carbohydrates, and lipids). Either produced endogenously or exogenously, reactive chemical species affect the survival of pathogens including the gram-positive
Staphylococcus aureus (S. aureus). Therefore, bacteria developed strategies to overcome the toxicity of reactive species.
S. aureus is a widely found opportunistic pathogen. In its niche, S. aureus is in permanent contact with surrounding microbes and host factors. Deciphering the deterministic factors
in these interactions could facilitate pinpointing novel bacterial targets. Identifying
the aforementioned targets is crucial to develop new strategies not only to kill the pathogenic organisms but also to enhance the normal flora to minimize the pathogenicity and virulence of potential pathogens. Moreover, targeting S. aureus stress response can be used
to overcome bacterial resistance against host-derived factors. In this study, I identify a novel
S. aureus stress response factor against reactive electrophilic, oxygen, and hypochlorite species to better understand its resilience as a pathogen.
Although bacterial stress response is an active research field, gene function is a current bottleneck in characterizing the understudied bacterial strategies to mediate stress conditions. I aimed at understanding the function of a novel protein family integrated
in many defense systems of several biological systems.
In bacteria, fungi, and plants, old yellow enzymes (OYEs) are widely found. Since the first isolation of the yellow flavoprotein, OYEs are used as biocatalysts for decades to reduce activated C=C bonds in α,β-unsaturated carbonyl compounds. The promiscuity
of the enzymatic catalysis is advantageous for industrial applications.
However, the physiological function of OYEs, especially in bacteria, is still puzzling.
Moreover, the relevance of the OYEs in infection conditions remained enigmatic.
Here, I show that there are two groups of OYEs (OYE flavin oxidoreductase, OfrA and OfrB) that are encoded in staphylococci and some firmicutes. OfrA (SAUSA300_0859) is more conserved than OfrB (SAUSA300_0322) in staphylococci and is a part of the staphylococcal core genome.
A reporter system was established to report for ofrA in S. aureus background.
The results showed that ofrA is induced under electrophilic, oxidative, and hypochlorite stress. OfrA protects S. aureus against quinone, methylglyoxal, hydrogen peroxide,
and hypochlorite stress. Additionally, the results provide evidence that OfrA supports
thiol-dependent redox homeostasis. At the host-pathogen interface, OfrA promotes S. aureus fitness in murine macrophage cell line. In whole human blood, OfrA is involved in S. aureus survival indicating a potential clinical relevance to bacteraemia.
In addition, ofrA mutation affects the production of the virulence factor staphyloxanthin via the upper mevalonate pathway. In summary, decoding OfrA function and its proposed mechanism of action in S. aureus shed the light on a conserved stress response within multiple organisms.
Maintaining the balance between CO2 uptake and transpiration is important for plants and depends on tightly controlled turgor changes caused by the activity of various anion and cation channels. These channels are part of signaling cascades triggered, for example, by phytohormones such as ABA (abscisic acid) and JA (jasmonate), both of which act during drought stress in guard cells. In addition, JA is known to be involved in the plant's response to pathogen attack or wounding.
GORK (guard cell outward rectifying K+ channel) is the only known outward rectifying K+ channel in guard cells and therefore responsible for K+ efflux during stomatal closure.
In the course of this work it could be demonstrated by stomatal aperture assays, that GORK is an essential part of JA-induced stomatal closure. This is true for both triggers, leaf wounding as well as direct MeJA (methyl jasmonate) application. Patch clamp experiments on guard cell protoplasts backed this finding by revealing GORK K+ outward currents as a target of JA signaling in guard cells. As cytosolic Ca2+ signals are known to be involved in both ABA as well as JA signaling, the interaction of GORK with Ca2+-dependent kinases was examined consequently. An antagonistic regulation of GORK by
CIPK5-CBL1/9 complexes and ABI2 was identified by DEVC (double electrode voltage clamp) and protein-protein interaction experiments and backed up by in vitro kinase assays. Patch-clamp recordings on guard cell protoplasts of cipk5-2 kinase loss-of-function mutant revealed the importance of CIPK5 for JA-triggered stomatal closure via activation of GORK. The interaction of different CDPKs (Ca2+-dependent protein kinases) with GORK was also investigated.
Besides Ca2+ signaling also ROS (reactive oxygen species) production is essential in ABA and MeJA signaling. In DEVC experiments a reversible effect of ROS on GORK channel activity could be demonstrated, which could be one piece in the explanation of those ROS effects in ABA and MeJA signaling.
In this thesis, a new approach of a qNMR method has been investigated to demonstrate the reliability and importance of this method as an alternative solution for analyzing oil quality parameters, especially in RFO, which has particular characteristics (red color). This study also includes the chemometric evaluation of spectral data for authentication, visual grouping, and prediction of RFO quality based on the degree of unsaturation, FFA value, and unsaturated fatty acid content.
The analytical measurement procedure of NMR spectroscopy begins with optimization of the analytical acquisition parameters, including effect of solvent, effect of sample concentration, selection of appropriate internal standards, determination of T1, and method validation. Furthermore, the results of the method development were interpreted to RFO samples evaluation, which began with determining the assignment of signal spectra for the determination of AV, SV, EV, and IV simultaneously with: the hydrolysis approach and standard addition of palmitic acid.
Background
Complex regional pain syndrome (CRPS) develops after injury and is characterized by disproportionate pain, oedema, and functional loss. CRPS has clinical signs of neuropathy as well as neurogenic inflammation. Here, we asked whether skin biopsies could be used to differentiate the contribution of these two systems to ultimately guide therapy. To this end, the cutaneous sensory system including nerve fibres and the recently described nociceptive Schwann cells as well as the cutaneous immune system were analysed.
Methods
We systematically deep-phenotyped CRPS patients and immunolabelled glabrous skin biopsies from the affected ipsilateral and non-affected contralateral finger of 19 acute (< 12 months) and 6 chronic (> 12 months after trauma) CRPS patients as well as 25 sex- and age-matched healthy controls (HC). Murine foot pads harvested one week after sham or chronic constriction injury were immunolabelled to assess intraepidermal Schwann cells.
Results
Intraepidermal Schwann cells were detected in human skin of the finger—but their density was much lower compared to mice. Acute and chronic CRPS patients suffered from moderate to severe CRPS symptoms and corresponding pain. Most patients had CRPS type I in the warm category. Their cutaneous neuroglial complex was completely unaffected despite sensory plus signs, e.g. allodynia and hyperalgesia. Cutaneous innate sentinel immune cells, e.g. mast cells and Langerhans cells, infiltrated or proliferated ipsilaterally independently of each other—but only in acute CRPS. No additional adaptive immune cells, e.g. T cells and plasma cells, infiltrated the skin.
Conclusions
Diagnostic skin punch biopsies could be used to diagnose individual pathophysiology in a very heterogenous disease like acute CRPS to guide tailored treatment in the future. Since numbers of inflammatory cells and pain did not necessarily correlate, more in-depth analysis of individual patients is necessary.
Emotional dysregulation and its pathways to suicidality in a community-based sample of adolescents
(2024)
Objective
Effective suicide prevention for adolescents is urgently needed but difficult, as suicide models lack a focus on age-specific influencing factors such as emotional dysregulation. Moreover, examined predictors often do not specifically consider the contribution to the severity of suicidality.
To determine which adolescents are at high risk of more severe suicidality, we examined the association between emotional dysregulation and severity of suicidality directly as well as indirectly via depressiveness and nonsuicidal self-injury.
Method
Adolescents from 18 high schools in Bavaria were included in this cross-sectional and questionnaire-based study as part of a larger prevention study. Data were collected between November 2021 and March 2022 and were analyzed from January 2023 to April 2023.
Students in the 6th or 7th grade of high school (11–14 years) were eligible to participate. A total of 2350 adolescents were surveyed and data from 2117 students were used for the analyses after excluding incomplete data sets. Our main outcome variable was severity of suicidality (Paykel Suicide Scale, PSS). Additionally, we assessed emotional dysregulation (Difficulties in Emotion Regulation Scale, DERS-SF), depressiveness (Patient Health Questionnaire, PHQ-9) and nonsuicidal self-injury (Deliberate Self-Harm Inventory, DSHI).
Results
In total, 2117 adolescents (51.6% female; mean age, 12.31 years [standard deviation: 0.67]) were included in the structural equation model (SEM). Due to a clear gender-specific influence, the model was calculated separately for male and female adolescents. For male adolescents, there was a significant indirect association between emotional dysregulation and severity of suicidality, mediated by depressiveness (β = 0.15, SE = .03, p = .008). For female adolescents, there was a significant direct path from emotional dysregulation to severity of suicidality and also indirect paths via depressiveness (β = 0.12, SE = .05, p = 0.02) and NSSI (β = 0.18, SE = .04, p < .001).
Conclusions
Our results suggest that gender-related risk markers in 11–14-year-olds need to be included in future suicide models to increase their predictive power. According to our findings, early detection and prevention interventions based on emotion regulation skills might be enhanced by including gender-specific adjustments for the co-occurrence of emotional dysregulation, depressiveness, and nonsuicidal self-injury in girls and the co-occurrence of emotional dysregulation and depressiveness in boys.
The hallmark oncoprotein Myc is a major driver of tumorigenesis in various human cancer entities. However, Myc’s structural features make it challenging to develop small molecules against it. A promising strategy to indirectly inhibit the function of Myc is by targeting its interactors. Many Myc-interacting proteins have reported scaffolding functions which are difficult to target using conventional occupancy- driven inhibitors. Thus, in this thesis, the proteolysis targeting chimera (PROTAC) approach was used to target two oncoproteins interacting with Myc which promote the oncogenicity of Myc, Aurora-A and WDR5. PROTACs are bifunctional small molecules that bind to the target protein with one ligand and recruit a cellular E3- ligase with the other ligand to induce target degradation via the ubiquitin- proteasome system. So far, the most widely used E3-ligases for PROTAC development are Cereblon (CRBN) and von Hippel–Lindau tumor suppressor (VHL). Furthermore, there are cases of incompatibility between some E3-ligases and proteins to bring about degradation. Hence there is a need to explore new E3- ligases and a demand for a tool to predict degradative E3-ligases for the target protein in the PROTAC field.
In the first part, a highly specific mitotic kinase Aurora-A degrader, JB170, was developed. This compound utilized Aurora-A inhibitor alisertib as the target ligand and thalidomide as the E3-ligase CRBN harness. The specificity of JB170 and the ternary complex formation was supported by the interactions between Aurora-A and CRBN. The PROTAC-mediated degradation of Aurora-A induced a distinct S- phase defect rather than mitotic arrest, shown by its catalytic inhibition. The finding demonstrates that Aurora-A has a non-catalytic role in the S-phase. Furthermore, the degradation of Aurora-A led to apoptosis in various cancer cell lines.
In the second part, two different series of WDR5 PROTACs based on two protein- protein inhibitors of WDR5 were evaluated. The most efficient degraders from both series recruited VHL as a E3-ligase and showed partial degradation of WDR5. In addition, the degradation efficiency of the PROTACs was significantly affected by the linker nature and length, highlighting the importance of linker length and composition in PROTAC design. The degraders showed modest proliferation defects at best in cancer cell lines. However, overexpression of VHL increased the degradation efficiency and the antiproliferative effect of the PROTACs.
In the last part, a rapamycin-based assay was developed to predict the degradative E3-ligase for a target. The assay was validated using the WDR5/VHL and Aurora- A/CRBN pairs. The result that WDR5 is degraded by VHL but not CRBN and Aurora-A is degraded by CRBN, matches observations made with PROTACs. This technique will be used in the future to find effective tissue-specific and essential E3-ligases for targeted degradation of oncoproteins using PROTACs.
Collectively, the work presented here provides a strategy to improve PROTAC development and a starting point for developing Aurora-A and WDR5 PROTACs for cancer therapy.
Humans actively interact with the world through a wide range of body movements. To understand human cognition in its natural state, we need to incorporate ecologically relevant body movement into our account. One fundamental body movement during daily life is natural walking. Despite its ubiquity, the impact of natural walking on brain activity and cognition has remained a realm underexplored.
In electrophysiology, previous studies have shown a robust reduction of ongoing alpha power in the parieto-occipital cortex during body movements. However, what causes the reduction of ongoing alpha, namely whether this is due to body movement or prevalent sensory input changes, was unknown. To clarify this, study 1 was performed to test if the alpha reduction is dependent on visual input. I compared the resting state alpha power during natural walking and standing, in both light and darkness. The results showed that natural walking led to decreased alpha activity over the occipital cortex compared to standing, regardless of the lighting condition. This suggests that the movement-induced modulation of occipital alpha activity is not driven by visual input changes during walking. I argue that the observed alpha power reduction reflects a change in the state of the subject based on disinhibition induced by walking. Accordingly, natural walking might enhance visual processing and other cognitive processes that involve occipital cortical activity.
I first tested this hypothesis in vision. Study 2 was performed to examine the possible effects of natural walking across visual processing stages by assessing various neural markers during different movement states. The findings revealed an amplified early visual response, while a later visual response remain unaffected. A follow-up study 3 replicated the walking-induced enhancement of the early visual evoked potential and showed that the enhancement was dependent on specific stimulus-related parameters (eccentricity, laterality, distractor presence). Importantly, the results provided evidence that the enhanced early visual responses are indeed linked to the modulation of ongoing occipital alpha power. Walking also modulated the stimulus-induced alpha power. Specifically, it showed that when the target appeared in the fovea area without a distractor, walking exhibited a significantly reduced modulation of alpha power, and showed the largest difference to standing condition. This effect of eccentricity indicates that during later visual processing stages, the visual input in the fovea area is less processed than in peripheral areas while walking.
The two visual studies showed that walking leads to an enhancement in temporally early visual processes which can be predicted by the walking-induced change in ongoing alpha oscillation likely marking disinhibition. However, while walking affects neural markers of early sensory processes, it does not necessarily lead to a change in the behavioural outcome of a sensory task. The two visual studies suggested that the behavioural outcome seems to be mainly based on later processing stages.
To test the effects of walking outside the visual domain, I turned to audition in study 4. I investigated the influence of walking in a particular path vs. simply stepping on auditory processing. Specifically, the study tested whether enhanced processing due to natural walking can be found in primary auditory brain activity and whether the processing preferences are dependent on the walking path. In addition, I tested whether the changed spatial processing that was reported in previous visual studies can be seen in the auditory domain. The results showed enhanced sensory processing due to walking in the auditory domain, which was again linked to the modulation of occipital alpha oscillation. The auditory processing was further dependent on the walking path. Additionally, enhanced peripheral sensory processing, as found in vision, was also present in audition.
The findings outside vision supported the idea of natural walking affecting cognition in a rather general way. Therefore in my study 5, I examined the effect of natural walking on higher cognitive processing, namely divergent thinking, and its correlation with the modulation of ongoing alpha oscillation. I analyzed alpha oscillations and behavioural performance during restricted and unrestricted movement conditions while subjects completed a Guilford's alternate uses test. The results showed that natural walking, as well as missing body restriction, reduces the occipital alpha ongoing power independent of the task phase which goes along with higher test scores. The occipital alpha power reduction can therefore be an indicator of a changed state that allows improved higher cognitive processes.
In summary, the research presented in this thesis highlights that natural walking can change different processes in the visual and auditory domain as well as higher cognitive processes. The effect can be attributed to the movement of natural walking itself rather than to changes in sensory input during walking. The results further indicate that the walking-induced modulation of ongoing occipital alpha oscillations drives the cognitive effects. We therefore suggest that walking changes the inhibitory state which can influence awareness and attention. Such a mechanism could facilitate an adaptive enhancement in cognitive processes and thereby optimize movement-related behaviour such as navigation.
Compared to other countries, China was particularly early in developing a comprehensive set of policies to promote electric mobility (e-mobility). The aim of this study is to examine how China’s e-mobility development – through changes in formal institutions as well as market forces – has affected German passenger car manufacturers and their competitive environment and positions. The study is guided by two strands of research: new institutional economics and strategic management literature. A holistic multiple-case design is used to analyze five German case study firms. Qualitative interview data are collected through interviews and analyzed using a thematic analysis. The results show that the electric transformation in China has been shaped by changes in formal institutions at the macro, meso, and micro levels. Interestingly, the case study firms were affected not only by changes in China’s formal institutions but also by disparities between institutions in China and Europe. Furthermore, the data suggest that German car manufacturers are facing an increasingly competitive environment in China: at least four forces in Porter’s five-forces model seem to have intensified in recent years. The extent to which the case study firms have been affected by these developments may depend on the industry segments in which they are positioned. However, it can be argued that the electric transition has blurred the lines between traditional segments of the car industry to some extent. The interview data do not provide evidence that any of the German car brands have substantially changed their positioning, but they do suggest that some of the case study companies did not have an adequate offering for the Chinese market at the time of the interviews. In addition, the study finds that China’s transition to e-mobility has led to changes in various parts of the German automakers’ value chains, including production, sales, marketing, services, research and development, and procurement. Whether these changes will ultimately result in competitive advantage, parity, or disadvantage remains to be seen.
Introduction.
Mobile health (mHealth) integrates mobile devices into healthcare, enabling remote monitoring, data collection, and personalized interventions. Machine Learning (ML), a subfield of Artificial Intelligence (AI), can use mHealth data to confirm or extend domain knowledge by finding associations within the data, i.e., with the goal of improving healthcare decisions. In this work, two data collection techniques were used for mHealth data fed into ML systems: Mobile Crowdsensing (MCS), which is a collaborative data gathering approach, and Ecological Momentary Assessments (EMA), which capture real-time individual experiences within the individual’s common environments using questionnaires and sensors. We collected EMA and MCS data on tinnitus and COVID-19. About 15 % of the world’s population suffers from tinnitus.
Materials & Methods.
This thesis investigates the challenges of ML systems when using MCS and EMA data. It asks: How can ML confirm or broad domain knowledge? Domain knowledge refers to expertise and understanding in a specific field, gained through experience and education. Are ML systems always superior to simple heuristics and if yes, how can one reach explainable AI (XAI) in the presence of mHealth data? An XAI method enables a human to understand why a model makes certain predictions. Finally, which guidelines can be beneficial for the use of ML within the mHealth domain? In tinnitus research, ML discerns gender, temperature, and season-related variations among patients. In the realm of COVID-19, we collaboratively designed a COVID-19 check app for public education, incorporating EMA data to offer informative feedback on COVID-19-related matters. This thesis uses seven EMA datasets with more than 250,000 assessments. Our analyses revealed a set of challenges: App user over-representation, time gaps, identity ambiguity, and operating system specific rounding errors, among others. Our systematic review of 450 medical studies assessed prior utilization of XAI methods.
Results.
ML models predict gender and tinnitus perception, validating gender-linked tinnitus disparities. Using season and temperature to predict tinnitus shows the association of these variables with tinnitus. Multiple assessments of one app user can constitute a group. Neglecting these groups in data sets leads to model overfitting. In select instances, heuristics outperform ML models, highlighting the need for domain expert consultation to unveil hidden groups or find simple heuristics.
Conclusion.
This thesis suggests guidelines for mHealth related data analyses and improves estimates for ML performance. Close communication with medical domain experts to identify latent user subsets and incremental benefits of ML is essential.
Background
Iron deficiency (ID) is the leading cause of anemia worldwide. The prevalence of preoperative ID ranges from 23 to 33%. Preoperative anemia is associated with worse outcomes, making it important to diagnose and treat ID before elective surgery. Several studies indicated the effectiveness of intravenous iron supplementation in iron deficiency with or without anemia (ID(A)). However, it remains challenging to establish reliable evidence due to heterogeneity in utilized study outcomes. The development of a core outcome set (COS) can help to reduce this heterogeneity by proposing a minimal set of meaningful and standardized outcomes. The aim of our systematic review was to identify and assess outcomes reported in randomized controlled trials (RCTs) and observational studies investigating iron supplementation in iron-deficient patients with or without anemia.
Methods
We searched MEDLINE, CENTRAL, and ClinicalTrials.gov systematically from 2000 to April 1, 2022. RCTs and observational studies investigating iron supplementation in patients with a preoperative diagnosis of ID(A), were included. Study characteristics and reported outcomes were extracted. Outcomes were categorized according to an established outcome taxonomy. Quality of outcome reporting was assessed with a pre-specified tool. Reported clinically relevant differences for sample size calculation were extracted.
Results
Out of 2898 records, 346 underwent full-text screening and 13 studies (five RCTs, eight observational studies) with sufficient diagnostic inclusion criteria for iron deficiency with or without anemia (ID(A)) were eligible. It is noteworthy to mention that 49 studies were excluded due to no confirmed diagnosis of ID(A). Overall, 111 outcomes were structured into five core areas including nine domains. Most studies (92%) reported outcomes within the ‘blood and lymphatic system’ domain, followed by “adverse event” (77%) and “need for further resources” (77%). All of the latter reported on the need for blood transfusion. Reported outcomes were heterogeneous in measures and timing. Merely, two (33%) of six prospective studies were registered prospectively of which one (17%) showed no signs of selective outcome reporting.
Conclusion
This systematic review comprehensively depicts the heterogeneity of reported outcomes in studies investigating iron supplementation in ID(A) patients regarding exact definitions and timing. Our analysis provides a systematic base for consenting to a minimal COS.
Systematic review registration
PROSPERO CRD42020214247
Angesichts aktueller und zurückliegender Migrations- und Fluchtprozesse in Deutschland kommen Jugendliche der Residenzgesellschaft in verschiedenen Bereichen ihres Lebens mit Menschen mit Flucht- oder Migrationserfahrung in Kontakt, woraus sich Chancen und Entwicklungspotenziale, aber auch Herausforderungen ergeben. Beispielsweise kann vermehrter interkultureller Kontakt auf individueller Ebene zur Weiterentwicklung von Toleranz und Empathie führen. Jedoch können Jugendliche der Residenzgesellschaft auf vermehrte Zuwanderung auch mit einem Gefühl der Unsicherheit und einer ablehnenden Haltung gegenüber Menschen mit Flucht- oder Migrationserfahrung reagieren. Diese Reaktionen können durch einseitige oder negative Medienberichte zum Themenkomplex Flucht und Migration verstärkt werden. Um Chancen und Entwicklungspotenziale ausschöpfen sowie Herausforderungen im Kontext von Flucht und Migration bewältigen zu können, müssen Jugendliche in der Entwicklung interkultureller Kompetenz gefördert werden. Interkulturelle Kompetenz ist eine wesentliche Voraussetzung für das Zusammenleben in einer pluralistischen Gesellschaft und daher ein bedeutsames Bildungs- und Erziehungsziel für Schule und Unterricht.
Die Zielstellung der vorliegenden Forschungsarbeit ist demnach die praxis- und theorieorientierte Entwicklung und Evaluation eines Unterrichtskonzepts zur Förderung interkultureller Kompetenz unter Verwendung digitaler Medienangebote und Gestaltung medialer Beiträge.
Hinsichtlich theoretischer Grundlagen zu interkultureller Kompetenz wird vor dem Hintergrund eines an Offenheit, Prozesshaftigkeit und Heterogenität orientierten Kulturbegriffs Interkulturalität als sozialer Prozess verstanden, in dem sich Personen unterschiedlicher kultureller bzw. kollektiver Zugehörigkeiten begegnen, miteinander interagieren und kommunizieren. Interkulturelle Kompetenz setzt sich aus Wissen (kognitive Dimension), Einstellungen (affektive Dimension) sowie Verhaltensweisen (behaviorale Dimension) zusammen und es wird angenommen, dass diese erlernt und gefördert werden kann. Vorgehensweisen zur Entwicklung interkultureller Kompetenz sollten die kognitive, affektive und behaviorale Dimension interkultureller Kompetenz adressieren, die Reflexion authentischer, kritischer Überschneidungssituationen einbeziehen sowie realweltliche, interkulturelle Begegnungen als Lerngelegenheiten aufgreifen.
Bezüglich theoretischer Grundlagen zum Lehren und Lernen mit Medien stellt vor dem Hintergrund verschiedener Ansätze zum Lehren und Lernen mit Medien die handlungs- und entwicklungsorientierte Didaktik eine bedeutsame Grundlage für die vorliegende Forschungsarbeit dar. Sie wird bezüglich der Prinzipien der Situations-, Bedürfnis-, Erfahrungs- und Entwicklungsorientierung, der Bedeutsamkeit komplexer, lernprozessanregender Aufgabenstellungen und einer idealtypischen Strukturierung von Unterricht mit theoretischen Grundlagen interkultureller Kompetenz und Vorgehensweisen zu ihrer Förderung in Beziehung gesetzt.
Hinsichtlich des forschungsmethodischen Vorgehens wird auf Basis einer Gegenüberstellung verschiedener Ansätze der gestaltungsorientierten Bildungsforschung der Ansatz einer praxis- und theorieorientierten Entwicklung und Evaluation von Konzepten unterrichtlichen Handelns für die vorliegende Forschungsarbeit begründet ausgewählt und seine Umsetzung erläutert.
Im Rahmen der ersten Studie wird auf der Basis theoretischer und empirischer Grundlagen interkultureller Kompetenz und didaktischer Zugänge ein pädagogisches Konzept zur Förderung interkultureller Kompetenz von Schülerinnen und Schülern der Sekundarstufe I unter Verwendung digitaler Medien entwickelt und für eine achte Klasse am Gymnasium konkretisiert. Das Konzept wird hinsichtlich seiner Zielerreichung sowie auftretender Nebenwirkungen unter Einsatz von Mixed Methods evaluiert. Die Ergebnisse weisen unter anderem darauf hin, dass das entwickelte Unterrichtskonzept zur Förderung interkultureller Kompetenz der Schülerinnen und Schüler beigetragen hat.
Die zweite Studie stellt eine ergänzende qualitative Studie dar, mit dem Ziel, die gemeinsame Mediengestaltung in Zusammenarbeit von Lernenden mit und ohne Flucht- bzw. Migrationserfahrung als bedeutsame Lernaktivität des Unterrichtskonzepts vertiefend zu untersuchen und Vorgehensweisen des kollaborativen Gestaltungsprozesses, die aus der Perspektive der Schülerinnen und Schüler wichtig sind, zu identifizieren. Hierzu werden die subjektiven Sichtweisen der Gymnasiastinnen und Gymnasiasten auf die Gestaltung medialer Beiträge in interkultureller Begegnung unter Bezugnahme auf interkulturelle Sensibilität in Fokusgruppen erhoben und qualitativ-inhaltsanalytisch ausgewertet. Die Ergebnisse der qualitativen Inhaltsanalyse zeigen, dass im Rahmen der Mediengestaltung verschiedene Komponenten interkultureller Sensibilität angesprochen wurden. Beispielsweise geben einige Gymnasiastinnen und Gymnasiasten an, dass ihnen sowohl die Zusammenarbeit mit den Mittelschülerinnen und -schülern als auch die gemeinsame Mediengestaltung Freude bereitete.
In der dritten Studie werden die von den Schülerinnen und Schülern gestalteten Medienbeiträge aus interkulturell-kommunikativer und medienbezogener Perspektive vertiefend analysiert. Die Auswertung erfolgt durch qualitative Inhaltsanalysen hinsichtlich wesentlicher Aspekte der Kommunikationssituation, der Medienmerkmale sowie Bezugspunkten zur behavioralen Dimension interkultureller Kompetenz. Aus den Ergebnissen der Videoanalysen geht unter anderem hervor, dass die interkulturellen Begegnungssituationen, die im Rahmen der Beiträge dargestellt werden, aus kommunikationstheoretischer Perspektive komplex und vielschichtig sind.
Nach einer abschließenden kritischen Methodenreflexion werden Ergebnisse der Studien zusammengeführt und interpretiert. Beispielsweise geht aus der Zusammenführung der Ergebnisse aus der ersten und der zweiten Studie hervor, dass sich zwischen Pre- und Post-Test eine statistisch signifikante Steigerung des Mittelwertes der Komponente Aufmerksamkeit während der interkulturellen Interaktion ergibt, was unter Berücksichtigung der Resultate aus den Fokusgruppen als gesteigertes Interesse der Probandinnen und Probanden an den Schülerinnen und Schülern der Mittelschulklasse im Laufe der gemeinsamen Videogestaltung gedeutet werden kann. Die vergleichende Betrachtung von Ergebnissen aus der ersten und der dritten Studie zeigt, dass mit einer Steigerung des Summenscores der behavioralen Dimension interkultureller Kompetenz Bezüge zu verschiedenen Komponenten der behavioralen Dimension im Rahmen der gestalteten Videos in Verbindung stehen.
Hinsichtlich der Konsequenzen für zukünftige Forschung wird abschließend auf die Notwendigkeit der Entwicklung von Verfahren zur Erfassung interkultureller Kompetenz von Jugendlichen mit unzureichenden Deutschkenntnissen verwiesen. Bezüglich der Praxis in Schule und Unterricht ist die Förderung interkultureller Kompetenz unter Verwendung und Gestaltung digitaler Medienangebote bzw. -beiträge als schulische Querschnittsaufgabe aller Jahrgangsstufen, Fächer und Schulformen wahrzunehmen. Insgesamt leistet die vorliegende Forschungsarbeit damit einen Beitrag zur Verknüpfung der Förderung interkultureller Kompetenz mit der interkulturell-kooperativen Gestaltung medialer Beiträge.
This doctoral thesis investigates magneto-optical properties of mercury telluride layers grown tensile strained on cadmium telluride substrates. Here, layer thicknesses start above the usual quantum well thickness of about 20 nm and have a upper boundary around 100 nm due to lattice relaxation effects. This kind of layer system has been attributed to the material class of three-dimensional topological insulators in numerous publications. This class stands out due to intrinsic boundary states which cross the energetic band gap of the layer's bulk.
In order to investigate the band structure properties in a narrow region around the Fermi edge, including possible boundary states, the method of highly precise time-domain Terahertz polarimetry is used. In the beginning, the state of the art of Teraherz technology at the start of this project is discussed, moving on to a detailed description and characterization of the self-built measurement setup. Typical standard deviation of a polarization rotation or ellipticity measurement are on the order of 10 to 100 millidegrees, according to the transmission strength through investigated samples. A range of polarization spectra, depending on external magnetic fields up to 10 Tesla, can be extracted from the time-domain signal via Fourier transformation.
The identification of the actual band structure is done by modeling possible band structures by means of the envelope function approximation within the framework of the k·p method. First the bands are calculated based on well-established model parameters and from them the possible optical transitions and expected ellipticity spectra, all depending on external magnetic fields and the layer's charge carrier concentration. By comparing expected with measured spectra, the validity of k·p models with varying depths of detail is analyzed throughout this thesis. The rich information encoded in the ellipitcity spectra delivers key information for the attribution of single optical transitions, which are not part of pure absorption spectroscopy. For example, the sign of the ellipticity signals is linked to the mix of Landau levels which contribute to an optical transition, which shows direct evidence for bulk inversion asymmetry effects in the measured spectra.
Throughout the thesis, the results are compared repeatedly with existing publications on the topic. It is shown that the models used there are often insufficient or, in worst case, plainly incorrect. Wherever meaningful and possible without greater detours, the differences to the conclusions that can be drawn from the k·p model are discussed.
The analysis ends with a detailed look on remaining differences between model and measurement. It contains the quality of model parameters as well as different approaches to integrate electrostatic potentials that exist in the structures into the model.
An outlook on possible future developments of the mercury cadmium telluride layer systems, as well as the application of the methods shown here onto further research questions concludes the thesis.
Neisseria meningitidis (the meningococcus) is one of the major causes of bacterial meningitis, a life-threatening inflammation of the meninges. Traversal of the meningeal blood-cerebrospinal fluid barrier (mBCSFB), which is composed of highly specialized brain endothelial cells (BECs), and subsequent interaction with leptomeningeal cells (LMCs) are critical for disease progression. Due to the human-exclusive tropism of N. meningitidis, research on this complex host-pathogen interaction is mostly limited to in vitro studies. Previous studies have primarily used peripheral or immortalized BECs alone, which do not retain relevant barrier phenotypes in culture. To study meningococcal interaction with the mBCSFB in a physiologically more accurate context, BEC-LMC co-culture models were developed in this project using BEC-like cells derived from induced pluripotent stem cells (iBECs) or hCMEC/D3 cells in combination with LMCs derived from tumor biopsies.
Distinct BEC and LMC layers as well as characteristic expression of cellular markers were observed using transmission electron microscopy (TEM) and immunofluorescence staining. Clear junctional expression of brain endothelial tight and adherens junction proteins was detected in the iBEC layer. LMC co-culture increased iBEC barrier tightness and stability over a period of seven days, as determined by sodium fluorescein (NaF) permeability and transendothelial electrical resistance (TEER). Infection experiments demonstrated comparable meningococcal adhesion and invasion of the BEC layer in all models tested, consistent with previously published data. While only few bacteria crossed the iBEC-LMC barrier initially, transmigration rates increased substantially over 24 hours, despite constant high TEER. After 24 hours of infection, deterioration of the barrier properties was observed including loss of TEER and altered expression of tight and adherens junction components. Reduced mRNA levels of ZO-1, claudin-5, and VE-cadherin were detected in BECs from all models. qPCR and siRNA knockdown data suggested that transcriptional downregulation of these genes was potentially but not solely mediated by Snail1. Immunofluorescence staining showed reduced junctional coverage of occludin, indicating N. meningitidis-induced post-transcriptional modulation of this protein, as previous studies have suggested. Together, these results suggest a potential combination of transcellular and paracellular meningococcal traversal of the mBCSFB, with the more accessible paracellular route becoming available upon barrier disruption after prolonged N. meningitidis infection. Finally, N. meningitidis induced cellular expression of pro-inflammatory cytokines and chemokines such as IL-8 in all mBCSFB models. Overall, the work described in this thesis highlights the usefulness of advanced in vitro models of the mBCSFB that mimic native physiology and exhibit relevant barrier properties to study infection with meningeal pathogens such as N. meningitidis.
Integrative, three-dimensional \(in\) \(silico\) modeling of gas exchange in the human alveolus
(2024)
The lung plays a vital role by exchanging respiratory gases. At the core of this gas exchange is a simple yet crucial passive diffusion process occurring within the alveoli. These balloon-like structures, connected to the peripheral airways, are surrounded by a dense network
of small capillaries. Here, inhaled air comes into close proximity with deoxygenated blood coming from the heart, enabling the exchange of oxygen and carbon dioxide across their concentration gradients.
The efficiency of gas exchange can be measured through indicators such as the diffusion capacity of the lung for oxygen and the reaction half-time. A notable discrepancy exists in humans between physiological estimates of diffusion capacity and the theoretical maximum capacity under optimal structural conditions (morphological estimate). This discrepancy is influenced by a range of interrelated factors, including structural elements like the surface area and thickness of the diffusion barrier, as well as physiological factors such as blood flow dynamics. To unravel the different roles of these factors, we investigated how morphological and physiological properties of the human alveolar micro-environment collectively and individually influence the process of gas exchange. To this end, we developed an integrative in silico approach combining 3D morphological modeling and simulation of blood flow and of oxygen transport.
At the core of our approach lies the simulation software Alvin, serving as an interactive platform for the underlying mathematical model of oxygen transport within the alveolus. Developed by integrating and expanding existing mathematical models, our spatio-temporal model produces results in agreement with experimental data. Alvin allows for real-time parameter adjustments and the execution of multiple simultaneous simulation instances and provides detailed quantitative feedback, offering an immersive exploration of the simulated gas exchange process. The morphological and physiological parameters at play were further investigated with a focus on the microvasculature. By compiling a stereological database from the literature and 3D geometric modeling, we created a sheet-flow model as a realistic representation of the morphology of the human alveolar capillary network. Blood flow was simulated using computational fluid dynamics. Our findings were in line with previous estimations and highlighted the crucial role of viscosity models in predicting pressure drop across the microvasculature. Furthermore, we showcased how our approach can be harnessed to explore structural details, such as the connectivity of the alveolar capillary network with the vascular tree, using blood flow indices. It is important to emphasize that
so far we have relied on different data sources and that experimental validation is needed to move forward.
Integration of our findings into Alvin allowed quantification of the simulated gas exchange process through the diffusion capacity for oxygen and reaction half-time. In addition to evaluating the collective influences of the morphological and physiological properties, our interactive software facilitates the assessment of individual parameter value changes. Exploring blood volume and surface area available for gas exchange revealed linear correlations with diffusion capacity. The blood flow velocity had a positive, non-linear effect on diffusion capacity. The reaction half-time confirmed that under normal conditions, the gas exchange process is not diffusion-limited. Collectively, our alveolar model yielded a diffusion capacity value that fell in the middle of previous physiological and morphological estimates, implying that alveolar-level phenomena contribute to 50% of the diffusion capacity limitations that occur in vivo.
In summary, our integrative in silico approach disentangles various structural and functional influences on alveolar gas exchange, complementing traditional investigations in respiratory
research. We further showcase its utility in teaching and the interpretation of published data. To advance our understanding, future work should prioritize obtaining a cohesive experimental data set and identifying an appropriate viscosity model for blood flow simulations.
Immunofluorescence is a common method to localise proteins within their cellular context via fluorophore labelled antibodies and for some applications without alternative. However, some protein targets evade detection due to low protein abundance or accessibility issues. In addition, some imaging methods require a massive reduction in antigen density thus impeding detection of even medium-abundant proteins.Here, we show that the fusion of the target protein to TurboID, a biotin ligase labelling lysine residues in close proximity, and subsequent detection of biotinylation by fluorescent streptavidin offers an “all in one” solution to the above-mentioned restrictions. For a wide range of target proteins tested, the streptavidin signal was significantly stronger than an antibody signal, markedly improving the imaging sensitivity in expansion microscopy and correlative light and electron microscopy, with no loss in resolution. Importantly, proteins within phase-separated regions, such as the central channel of the nuclear pores, the nucleolus or RNA granules, were readily detected with streptavidin, while most antibodies fail to label proteins in these environments. When TurboID is used in tandem with an HA epitope tag, co-probing with streptavidin and anti-HA can be used to map antibody-accessibility to certain cellular regions. As a proof of principle, we mapped antibody access to all trypanosome nuclear pore proteins (NUPs) and found restricted antibody labelling of all FG NUPs of the central channel that are known to be phase-separated, while most non-FG Nups could be labelled. Lastly, we show that streptavidin imaging can resolve dynamic, temporally and spatially distinct sub-complexes and, in specific cases, reveal a history of dynamic protein interaction.In conclusion, streptavidin imaging has major advantages for the detection of lowly abundant or inaccessible proteins and in addition, can provide information on protein interactions and biophysical environment.
Gegenstand der Arbeit ist eine internationale Untersuchung der urheberrechtlichen Schranke der sogenannten Panoramafreiheit oder Freiheit des Straßenbildes. Durch diese Schranke wird das Urheberrecht an Werken im öffentlichen Raum eingeschränkt. Auf unionsrechtlicher Ebene sieht die Richtlinie 2001/29/EG in Art. 5 Abs. 3 lit. h eine fakultative Schranke zugunsten der Freiheit des Straßenbildes vor. Diese fakultative Schranke wurde von den Mitgliedstaaten der Europäischen Union sehr unterschiedlich in nationales Recht umgesetzt. Nach § 59 des deutschen Urheberrechtsgesetzes ist es zulässig, Werke, die sich bleibend an öffentlichen Wegen, Straßen oder Plätzen befinden, mit Mitteln der Malerei oder Graphik, durch Lichtbild oder durch Film zu vervielfältigen, zu verbreiten und öffentlich wiederzugeben. Daneben gibt es auch Mitgliedstaaten, die die Schranke nicht oder nur eingeschränkt in nationales Recht umgesetzt haben. Auch Länder außerhalb der Europäischen Union sehen in nationalen Urheberrechtsgesetzen Regelungen zugunsten der Freiheit des Straßenbildes vor. Daher wurden im Rahmen der Arbeit verschiedene nationale Regelungen zur Panoramafreiheit gegenübergestellt, um die wesentlichen Unterschiede zwischen den Vorschriften zu untersuchen und herauszuarbeiten.
Ist bei Kraftfahrzeugen eine Anknüpfung an den Registrierungsort der Lex rei sitae vorzuziehen?
(2024)
„Die Doktorarbeit befasst sich mit der Frage, ob bei Kraftfahrzeugen eine Anknüpfung an den Registrierungsort der Lex rei sitae vorzuziehen sein könnte. Im Rahmen der Arbeit wird zu Beginn ermittelt, nach welchem Recht die überprüften Länder das anwendbare Recht bei Kraftfahrzeugen bestimmen. Sodann wird erörtert, ob der Registrierungsort in den überprüften Ländern überhaupt rechtssicher und stabil bestimmt werden kann. Dabei wird insbesondere auf die nationalen Vorschriften zur Registrierung von Kraftfahrzeugen und den weiteren Anknüpfungsmöglichkeiten, wie Fahrzeugzulassungsbescheinigung und KFZ-Kennzeichen, eingegangen. Anhand von Beispielsfällen werden abschließend die möglichen Veränderungen, durch eine Anknüpfung an den Registrierungsort im Gegen-satz zur lex rei sitae, gegenübergestellt. Ebenso wird die Frage der res in transitu, als auch die Frage, wie mit gestohlenen Fahrzeugen umgegangen werden kann, behandelt. Im Ergebnis kann eine rechtssichere Bestimmung des anwendbaren Rechts bestätigt wer-den.“
In this thesis, we apply the information-theoretic approach in the context of quantum dynamics and wave packet motion: Information-theoretic measures are calculated from position and momentum densities, which are obtained from time-dependent quantum wave functions. The aim of this thesis is to benchmark, analyze and interpret these quantities and relate their features to the wave packet dynamics. Firstly, this is done for the harmonic oscillator (HO) with and without static disorder. In the unperturbed HO, the analytical study of coherent and squeezed states reveals time-dependent entropy expressions related to the localization of the wave function. In the disordered HO, entropies from classical and quantum dynamics are compared for short and long times. In the quantum case, imprints of wave packet revivals are found in the entropy. Then, the energy dependence of the entropy for very long times is discussed. Secondly, this is donefor correlated electron-nuclear motion. Here, entropies derived from the total, electronic and nuclear density, respectively, are calculated in position and momentum space for weak and strong adiabatic electronic coupling. The correlation between electron and nucleus is investigated using different correlation measures, where some of these functions are sensitive to the nodal structure of the wave function. An analytic ansatz to interpret the information-theoretical quantities is applied as well.
The mold Aspergillus fumigatus (A. fumigatus) is known as human pathogen and can cause life-threatening infections in humans with a weakened immune system. This is a known complication in patients receiving glucocorticoids, e.g. after hematopoietic stem cell transplantation or solid organ transplantation. Although research in the field of immune cell/fungus interaction has discovered key strategies how immune cells fight against infectious fungi, our knowledge is still incomplete. In order to develop effective treatment options against fungal infections, a detailed understanding of their interactions is crucial. Thus, visualization of immune cell and fungus is an excellent approach to gain further knowledge. For a detailed view of such interaction processes, a high optical resolution on nanometer scale is required. There is a variety of super resolution microscopy techniques, enabling fluorescence imaging beyond the diffraction limit. This work combines the use of three complementary super resolution microscopy techniques, in order to study immune cell/fungus interaction from different points of view.
Aim of this work is the introduction of the recently invented imaging technique named expansion microscopy (ExM) for the study of immune cell/fungus interactions. The core aspect of this method is the physical magnification of the specimen, which increases the distance between protein structures that are close to each other and which can therefore be imaged separately.
The simultaneous magnification of primary human natural killer (NK) cells and A. fumigatus hyphae was established in this work using ExM. Reorganization of cytoskeletal components of interacting NK cells was demonstrated here, by expansion of the immunological synapse (IS), formed between NK cells and A. fumigatus. In addition, reorganization of the microtubule-organizing center (MTOC) towards fungal hyphae and an accumulation of actin at the IS has been observed. Furthermore, ExM has been used to visualize lytic granules of NK cells after degranulation. After magnification of the specimen, lysosome associated protein 1 (LAMP1) was shown to surround perforin. In absence of the plasma membrane-exposed degranulation marker LAMP1, a “ring-shaped” structure was often observed for fluorescently labeled perforin. Volume calculation of lytic granules demonstrated the benefit of ExM. Compared to pre-expansion images, analyses of post-expansion images showed two volume distributions for degranulated and non-degranulated NK cells. In addition, this work emphasizes the importance of determining the expansion factor for a structure in each species, as variations of expansion factors have been observed. This factor, as well as possible sample distortions should be considered, when ExM is used in order to analyze the interaction between two species.
A second focus of this work is the visualization of a chimeric antigen receptor (CAR), targeting an epitope on the cell wall of A. fumigatus. Structured illumination microscopy (SIM) revealed that the CAR is part of the immunological synapse of primary human CAR T cells and CAR-NK-92 cells. At the interaction site, an accumulation of the CAR was observed, as well as the presence of perforin. CAR accumulation at fungal hyphae was further demonstrated by automated live cell imaging of interacting CAR-NK-92 cells, expressing a fluorescent fusion protein.
Additionally, the use of direct stochastic optical reconstruction microscopy (dSTORM) gave first insights in CAR expression levels on the basal membrane of CAR-NK-92 cells, with single molecule sensitivity. CAR cluster analyses displayed a heterogeneous CAR density on the basal membrane of transfected NK 92 cells.
In summary, this work provides insights into the application of ExM for studying the interaction of primary human NK cells and A. fumigatus for the first time. Furthermore, this thesis presents first insights regarding the characterization of an A. fumigatus-targeting CAR, by applying super-resolution fluorescence microscopy, like SIM and dSTORM.
The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma. xCT activity was abolished by genetic depletion in the Tyr::CreER; Braf\(^{CA}\); Pten\(^{lox/+}\) melanoma model and by acute cystine withdrawal in melanoma cell lines. Both interventions profoundly impacted melanoma glutathione levels, but they were surprisingly well tolerated by murine melanomas in vivo and by most human melanoma cell lines in vitro. RNA sequencing of human melanoma cells revealed a strong adaptive upregulation of NRF2 and ATF4 pathways, which orchestrated the compensatory upregulation of genes involved in antioxidant defence and de novo cysteine biosynthesis. In addition, the joint activation of ATF4 and NRF2 triggered a phenotypic switch characterized by a reduction of differentiation genes and induction of pro-invasive features, which was also observed after erastin treatment or the inhibition of glutathione synthesis. NRF2 alone was capable of inducing the phenotypic switch in a transient manner. Together, our data show that cystine or glutathione levels regulate the phenotypic plasticity of melanoma cells by elevating ATF4 and NRF2.
Conspectus
Nature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese–calcium cluster (CaMn\(_4\)O\(_5\)) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC.
Transferring this concept from nature to the engineering of artificial metal catalysts for fuel production has fostered the fascinating field of metallosupramolecular chemistry by generating defined cavities that conceptually mimic enzymatic pockets. However, the application of supramolecular approaches to generate artificial water oxidation catalysts remained scarce prior to our initial reports, since such molecular design strategies for efficient activation of substrate water molecules in confined nanoenvironments were lacking. In this Account, we describe our research efforts on combining the state-of-the art Ru(bda) catalytic framework with structurally programmed ditopic ligands to guide the water oxidation process in defined metallosupramolecular assemblies in spatial proximity. We will elucidate the governing factors that control the quality of hydrogen-bonding water networks in multinuclear cavities of varying sizes and geometries to obtain high-performance, state-of-the-art water oxidation catalysts. Pushing the boundaries of artificial catalyst design, embedding a single catalytic Ru center into a well-defined molecular pocket enabled sophisticated water preorganization in front of the active site through an encoded basic recognition site, resulting in high catalytic rates comparable to those of the natural counterpart OEC-PSII.
To fully explore their potential for solar fuel devices, the suitability of our metallosupramolecular assemblies was demonstrated under (electro)chemical and photocatalytic water oxidation conditions. In addition, testing the limits of structural diversity allowed the fabrication of self-assembled linear coordination oligomers as novel photocatalytic materials and long-range ordered covalent organic framework (COF) materials as recyclable and long-term stable solid-state materials for future applications.
The reversible condensation of catechols and boronic acids to boronate esters is a paradigm reaction in dynamic covalent chemistry. However, facile backward hydrolysis is detrimental for stability and has so far prevented applications for boronate-based materials. Here, we introduce cubic boronate ester cages 6 derived from hexahydroxy tribenzotriquinacenes and phenylene diboronic acids with ortho-t-butyl substituents. Due to steric shielding, dynamic exchange at the Lewis acidic boron sites is feasible only under acid or base catalysis but fully prevented at neutral conditions. For the first time, boronate ester cages 6 tolerate substantial amounts of water or alcohols both in solution and solid state. The unprecedented applicability of these materials under ambient and aqueous conditions is showcased by efficient encapsulation and on-demand release of β-carotene dyes and heterogeneous water oxidation catalysis after the encapsulation of ruthenium catalysts.
A novel USP11-TCEAL1-mediated mechanism protects transcriptional elongation by RNA Polymerase II
(2024)
Deregulated expression of MYC oncoproteins is a driving event in many human cancers. Therefore, understanding and targeting MYC protein-driven mechanisms in tumor biology remain a major challenge.
Oncogenic transcription in MYCN-amplified neuroblastoma leads to the formation of the MYCN-BRCA1-USP11 complex that terminates transcription by evicting stalling RNAPII from chromatin. This reduces cellular stress and allows reinitiation of new rounds of transcription. Basically, tumors with amplified MYC genes have a high demand on well orchestration of transcriptional processes-dependent and independent from MYC proteins functions in gene regulation. To date, the cooperation between promoter-proximal termination and transcriptional elongation in cancer cells remains still incomplete in its understanding.
In this study the putative role of the dubiquitinase Ubiquitin Specific Protease 11 (USP11) in transcription regulation was further investigated. First, several USP11 interaction partners involved in transcriptional regulation in neuroblastoma cancer cells were identified. In particular, the transcription elongation factor A like 1 (TCEAL1) protein, which assists USP11 to engage protein-protein interactions in a MYCN-dependent manner, was characterized. The data clearly show that TCEAL1 acts as a pro-transcriptional factor for RNA polymerase II (RNAPII)-medi- ated transcription. In detail, TCEAL1 controls the transcription factor S-II (TFIIS), a factor that assists RNAPII to escape from paused sites. The findings claim that TCEAL1 outcompetes the transcription elongation factor TFIIS in a non-catalytic manner on chromatin of highly expressed genes. This is reasoned by the need regulating TFIIS function in transcription. TCEAL1 equili- brates excessive backtracking and premature termination of transcription caused by TFIIS.
Collectively, the work shed light on the stoichiometric control of TFIIS demand in transcriptional regulation via the USP11-TCEAL1-USP7 complex. This complex protects RNAPII from TFIIS-mediated termination helping to regulate productive transcription of highly active genes in neuroblastoma.
Autonomous mobile robots operating in unknown terrain have to guide
their drive decisions through local perception. Local mapping and
traversability analysis is essential for safe rover operation and low level
locomotion. This thesis deals with the challenge of building a local,
robot centric map from ultra short baseline stereo imagery for height
and traversability estimation.
Several grid-based, incremental mapping algorithms are compared and
evaluated in a multi size, multi resolution framework. A new, covariance
based mapping update is introduced, which is capable of detecting sub-
cellsize obstacles and abstracts the terrain of one cell as a first order
surface.
The presented mapping setup is capable of producing reliable ter-
rain and traversability estimates under the conditions expected for the
Cooperative Autonomous Distributed Robotic Exploreration (CADRE)
mission.
Algorithmic- and software architecture design targets high reliability
and efficiency for meeting the tight constraints implied by CADRE’s
small on-board embedded CPU.
Extensive evaluations are conducted to find possible edge-case scenar-
ios in the operating envelope of the map and to confirm performance
parameters. The research in this thesis targets the CADRE mission, but
is applicable to any form of mobile robotics which require height- and
traversability mapping.
In this study, we developed an innovative nanoparticle formulation to facilitate the delivery of antitumor antibodies to tumor sites. The study commenced with the utilization of 13 bispecific antibody fusion proteins, which targeted the Fn14 receptor, thereby validating the pivotal role of crosslinking in Fn14 receptor activation. Subsequently, gold nanoparticles were activated using COOH-PEG-SH in combination with EDC/NHS, and subsequently conjugated with two Fn14-targeting antibodies, PDL192 and 5B6. Following this, a pH-sensitive shell was generated on the outer layer of the antibody-coupled gold nanoparticles through the application of chemically modified polylysine. The resultant complexes, termed MPL-antibody-AuNP, demonstrated a release profile reminiscent of the tumor microenvironment (TME). Notably, these complexes released antibody-AuNPs only in slightly acidic conditions while remaining intact in neutral or basic environments. Functionality analysis further affirmed the pH-sensitive property of MPL-antibody-AuNPs, demonstrating that the antibodies only initiated potent Fn14 activation in slightly acidic environments. This formulation holds potential for applicability to antibodies or ligands targeting the 80 TNFRSF family, given that gold nanoparticles successfully served as platforms for antibody crosslinking, thereby transforming these antibodies into potent agonists. Moreover, the TME disintegration profile of MPL mitigates the potential cytotoxic effects of antibodies, thereby circumventing associated adverse side effects. This study not only showcases the potential of nanoparticle formulations in targeted therapy, but also provides a solid foundation for further investigations on their clinical application in the context of targeting category II TNFRSF receptors with antibodies or ligands.
Structure and dynamics of the plasma membrane: a single-molecule study in \(Trypanosoma\) \(brucei\)
(2024)
The unicellular, flagellated parasite Trypanosoma brucei is the causative agent of human African sleeping sickness and nagana in livestock. In the last decades, it has become an established eukaryotic model organism in the field of biology, as well as in the interdisciplinary field of biophysics. For instance, the dense variant surface glycoprotein (VSG) coat offers the possibility to study the dynamics of GPI-anchored proteins in the plasma membrane of living cells. The fluidity of the VSG coat is not only an interesting object of study for its own sake, but is critically important for the survival of the parasite in the mammalian host. In order to maintain the integrity of the coat, the entire VSG coat is recycled within a few minutes. This is surprisingly fast for a purely diffusive process with the flagellar pocket (FP) as the sole site for endo- and exocytosis. Previous studies characterising VSG dynamics using FRAP reported diffusion coefficients that were not sufficient to to enable fast turnover based on passive VSG randomisation on the trypanosome surface.
In this thesis, live-cell single-molecule fluorescence microscopy (SMFM) was employed to elucidate whether VSG diffusion coefficients were priorly underestimated or whether directed forces could be involved to bias VSGs towards the entrance of the FP. Embedding the highly motile trypanosomes in thermo-stable hydrogels facilitated the investigation of VSG dynamics on living trypanosomes at the mammalian host's temperature of 37°C. To allow for a spatial correlation of the VSG dynamics to the FP entrance, a cell line was employed harbouring a fluorescently labelled structure as a reference. Sequential two-colour SMFM was then established to allow for recording and registration of the dynamic and static single-molecule information.
In order to characterise VSG dynamics, an algorithm to obtain reliable information from short trajectories was adapted (shortTrAn). It allowed for the quantification of the local dynamics in two distinct scenarios: diffusion and directed motion. The adaptation of the algorithm to the VSG data sets required the introduction of an additional projection filter. The algorithm was further extended to take into account the localisation errors inherent to single-particle tracking. The results of the quantification of diffusion and directed motion were presented in maps of the trypanosome surface, including an outline generated from a super-resolved static structure as a reference. Information on diffusion was displayed in one map, an ellipse plot. The colour code represented the local diffusion coefficient, while the shape of the ellipses provided an indication of the diffusion behaviour (aniso- or isotropic diffusion). The eccentricity of the ellipses was used to quantify deviations from isotropic diffusion. Information on directed motion was shown in three maps: A velocity map, representing the amplitude of the local velocities in a colour code. A quiver plot, illustrating the orientation of directed motion, and a third map which indicated the relative standard error of the local velocities colour-coded. Finally, a guideline based on random walk simulations was used to identify which of the two motion scenarios dominated locally. Application of the guideline to the VSG dynamics analysed by shortTrAn yielded supermaps that showed the locally dominant motion mode colour-coded.
I found that VSG dynamics are dominated by diffusion, but several times faster than previously determined. The diffusion behaviour was additionally characterised by spatial heterogeneity. Moreover, isolated regions exhibiting the characteristics of round and elongated traps were observed on the cell surface. Additionally, VSG dynamics were studied with respect to the entrance of the FP. VSG dynamics in this region displayed similar characteristics compared to the remainder of the cell surface and forces biasing VSGs into the FP were not found.
Furthermore, I investigated a potential interference of the attachment of the cytoskeleton to the plasma membrane with the dynamics of VSGs which are anchored to the outer leaflet of the membrane. Preliminary experiments were conducted on osmotically swollen trypanosomes and trypanosomes depleted for a microtubule-associated protein anchoring the subpellicular microtubule cytoskeleton to the plasma membrane. The measurements revealed a trend that detachment of the cytoskeleton could be associated with a reduction in the VSG diffusion coefficient and a loss of elongated traps. The latter could be an indication that these isolated regions were caused by underlying structures associated with the cytoskeleton.
The measurements on cells with an intact cytoskeleton were complemented by random walk simulations of VSG dynamics with the newly determined diffusion coefficient on long time scales not accessible in experiments. Simulations showed that passive VSG randomisation is fast enough to allow for a turnover of the full VSG coat within a few minutes. According to an estimate based on the known rate of endocytosis and the newly determined VSG diffusion coefficient, the majority of exocytosed VSGs could escape from the FP to the cell surface without being immediately re-endocytosed.
Einleitung: Strukturelle Defekte der gastrointestinalen Hohlorgane stellen ein allgegen-wärtiges Problem im klinischen Alltag dar. Sie entstehen meist auf dem Boden einer ent-zündlichen oder tumorösen Grunderkrankung und können außerdem traumatisch sowie durch medizinische Eingriffe hervorgerufen werden. In der Folge kommt es zur Kontami-nation des umliegenden Gewebes mit Magen- bzw. Darminhalt, wodurch deletäre Folgen wie eine systemische Infektion, also eine Sepsis mit Multiorganversagen drohen können. Vor diesem Hintergrund sind gastrointestinale Defekte immer als potenziell lebensbedroh-lich für den Patienten zu betrachten. Die adäquate und kausale Behandlung erfolgt je nach Ätiologie und Zustand des Patienten durch eine Operation oder eine endoskopische Inter-vention. Hierzu stehen zahlreiche etablierte, operative und interventionelle Therapieme-thoden zur Verfügung. In manchen Fällen stoßen die etablierten Techniken jedoch an ihre Grenzen. Bei Patienten mit schwerwiegenden Komorbiditäten oder im Rahmen neuer me-dizinischer Verfahren sind Innovationen gefragt. Die Grundidee der vorliegenden Arbeit ist die Entwicklung einer biotechnologischen Therapieoption zur Versorgung gastrointesti-naler Hohlorganperforationen.
Methoden: Zur Durchführung einer Machbarkeitsstudie wurden zehn Göttinger Mi-nischweine in zwei Gruppen mit jeweils 5 Tieren aufgeteilt. Den Tieren der Experimental-gruppe wurden Hautbiopsien entnommen und daraus Fibroblasten isoliert, welche vo-rübergehend konserviert wurden. Unter Verwendung von azellularisiertem Schweinedarm erfolgte die Herstellung von Implantaten nach den Prinzipien des Tissue Engineerings. Die Tiere beider Gruppen wurden einer Minilaparotomie und einer ca. 3cm-Inzision der Ma-genvorderwand unterzogen. Die anschließende Versorgung wurde in der Experimental-gruppe durch Implantation der neuartigen Konstrukte erzielt. In der Kontrollgruppe wur-de im Sinne des Goldstandards eine konventionelle Naht durchgeführt. Anschließend wurden die Tiere für vier Wochen beobachtet. Eine bzw. zwei Wochen nach dem pri-mären Eingriff wurde bei allen Tieren beider Gruppen eine Laparoskopie bzw. Gastrosko-pie durchgeführt. Am Ende der klinischen Observationsphase wurden die Versuchstiere getötet und die entsprechenden Magenareale zur histologischen Untersuchung explantiert.
Ergebnisse: Die Herstellung der Implantate konnte auf der Basis standardisierter zellbio-logischer Methoden problemlos etabliert werden. Alle Tiere beider Gruppen überlebten den Primäreingriff sowie das vierwöchige Nachbeobachtungsintervall und zeigten dabei keine klinischen Zeichen möglicher Komplikationen. Die durchgeführten Laparoskopien und Gastroskopien ergaben bei keinem der Tiere Hinweise auf Leckagen oder lokale Infek-tionsprozesse. Die histologische Aufarbeitung zeigte im Bereich des ursprünglichen De-fekts eine bindegewebige Überbrückung sowie ein beginnendes Remodeling der Magen-schleimhaut in beiden Gruppen.
Schlussfolgerungen: Durch die Verknüpfung von Einzelprozessen der Zellkultur und dem Großtier-OP konnte ein neues Verfahren zum Verschluss gastrointestinaler Defekt erfolgreich demonstriert und etabliert werden. Das Projekt konnte reibungslos durchge-führt werden und lieferte Ergebnisse, die dem Goldstandard nicht unterlegen waren. Auf-grund der kleinen Fallzahl und weiterer methodischer Limitationen sind jedoch nur einge-schränkt Schlussfolgerungen möglich, weshalb die Durchführung größerer und gut geplan-ter Studien notwendig ist. Die Erkenntnisse dieser Pilotstudie liefern eine solide Basis für die Planung weiterführender Untersuchungen.
Different effects of conditional Knock-Out of Stat3 on the sensory epithelium of the Organ of Corti
(2024)
The mammalian cochlea detects sound in response to vibration at frequency-dependent positions along the cochlea duct. The sensory outer hair cells, which are surrounded by supporting cells, act as a signal amplifier by changing their cell length. This is called electromotility. To ensure correct electrical transmission during mechanical forces, a certain resistance of the sensory epithelium is a prerequisite for correct transduction of auditory information. This resistance is managed by microtubules and its posttranslational modification in the supporting cells of the sensory epithelium of the cochlea. Stat3 is a transcription factor, with its different phosphorylation sites, is involved in many cellular processes like differentiation, inflammation, cell survival and microtubule dynamics, depending on cell type and activated pathway. While Stat3 has a wide range of intracellular roles, the question arose, how and if Stat3 is involved in cells of the organ of Corti to ensure a correct hearing.
To test this, Cre/loxp system were used to perform conditional Knock-Out (cKO) of Stat3 in outer hair cells or supporting cells either before hearing onset or after hearing onset. Hearing performances included DPOAE and ABR measurements, while molecular were performed by sequencing. Additionally, morphological examination was used by immunohistochemistry and electron microscopy.
A cKO of Stat3 before and after hearing onset in outer hair cells leads to hearing impairments, whereas synapses, nerve fibers and mitochondria were not affected. Bulk sequencing analyzation of outer hair cells out of cKO mice before hearing onset resulted in a disturbance of cellular homeostasis and extracellular signals. A cKO of Stat3 in the outer hair cells after hearing onset resulted in inflammatory signaling pathway with increased cytokine production and upregulation of NF-kb pathway. In supporting cells, cKO of Stat3 only after hearing onset resulted in a hearing impairment. However, synapses, nerve soma and fibers were not affected of a cKO of Stat3 in supporting cells. Nevertheless, detyronisated modification of microtubules were altered, which can lead to an instability of supporting cells during hearing.
In conclusion, Stat3 likely interact in a cell-specific and function-specific manner in cells of the organ of Corti. While a cKO in outer hair cells resulted in increased cytokine production, supporting cells altered its stability due to decreased detyronisated modification of microtubules. Together the results indicated that Stat3 is an important protein for hearing performances. However, additional investigations of the molecular mechanism are needed to understand the role of Stat3 in the cells of the organ of Corti.
Dipolar merocyanines are very attractive supramolecular building blocks, as they combine interesting functional properties with strong, directional intermolecular interactions. The pyridine dioxocyano-pyridine (PYOP) chromophore (Chapter 2.2), used in this thesis, stands out because of its exceptionally high ground state dipole moment (g ~ 17 D), in combination with the option to retain good solubility also in unpolar solvents, by decoration with solubilizing groups.
The reliable binding motif of anti-parallel -stacking due to dipole-dipole interactions has allowed the design of molecular building blocks that form assemblies of predictable geometry. The intense unstructured charge transfer UV/Vis absorption band (eg ~ 10.7 D) is a result of the dominant contribution of the zwitterionic resonance structure which brings the PYOP chromophore just beyond the cyanine limit in solvents of low polarity (c2 = 0.60, 1,4 dioxane). The high sensitivity of the S0 – S1 UV/Vis absorption band to the environment manifests itself in a pronounced negative solvatochromism and strong H-type exciton coupling within -stacked PYOP assemblies. In accordance with the classical molecular exciton theory, an increasing hypsochromic shift of the dominant absorption band of these H aggregates can be observed as the stack size increases up to about six chromophores, where it levels out at about max ~ 440 nm (CHCl3). This allows a uniquely simple estimation of the number of interacting chromophores within the self-assembled structure from a single UV/Vis absorption spectrum of an aggregate.
The defined and well investigated PYOP dimer formation was employed in this thesis to probe the applicability and limitations of concentration-, temperature-, and solvent-dependent self-assembly studies (Chapter 3). Straightforward theoretical models to evaluate datasets of concentration-, temperature-, and solvent-dependent UV/Vis absorption by nonlinear regression analysis were derived for the case of dimer formation (Chapter 2.1). Although the dimer model is well known and widely applied in literature, this detailed derivation is helpful to understand assumptions and potential problems of the different approaches for the determination of thermodynamic parameters. This helps to decide on the most appropriate method to analyse a system of interest. In this regard it should be noted that covering a large portion of the self-assembly process with the experimental data is a prerequisite for the accuracy of the analysis. Additionally, many of the insights can also be transferred to other self-assembly systems like supramolecular polymerization or host-guest interactions.
The concentration-dependent analysis is the most straightforward method to investigate self-assembly equilibria. No additional assumptions, besides mass balance and mass action law, are required. Since it includes the least number of parameters (only K, if M/D are known), it is the most, or even only, reliable method, to elucidate the self-assembly mechanism of an unknown system by model comparison. To cover a large concentration range, however, the compound must be soluble enough and generally sample amounts at least in the low mg scale must be available.
The temperature-dependent analysis has the advantage that all thermodynamic parameters G0, H0 and S0 can be obtained from a single sample in one automated measurement. However, the accessible temperature-range is experimentally often quite limited and dependent on the solvent. For systems which do not show the transition from monomer to aggregate in a narrow temperature range, as given for, e.g., cooperative aggregation or processes with a high entropy contribution, often not the entire self-assembly process can be monitored. Furthermore, the assumptions of temperature-independent extinction coefficients of the individual species as well as temperature-independent H0 and S0 must be met. Monte Carlo simulations of data sets demonstrated that even minor changes in experimental data can significantly impact the optimized values for H0 and S0. This is due to the redundancy of these two parameters within the model framework and even small thermochromic effects can significantly influence the results. The G0 value, calculated from H0 and S0, is, however, still rather reliable.
Solvent-dependent studies can often cover the entire self-assembly process from monomeric (agg = 0) to the fully aggregated state (agg = 1). However, for dyes with strong solvatochromic effects, such as the dipolar merocyanines investigated in this thesis, the results are affected. Also, the assumption of a linear relation of the binding energy G0 and the fraction of denaturating solvent f, which is based on linear free energy relationships between G0 and the solvent polarity, can lead to errors. Especially when specific solvent effects are involved.
For the evaluation of experimental data by nonlinear regression, general data analysis software can be used, where user-defined fit models and known parameters can be implemented as desired. Alternatively, multiple specialized programs for analysing self-assembly data are available online. While the latter programs are usually more user-friendly, they have the disadvantage of being a “black box” where only pre-implemented models can be used without the option for the user to adapt models or parameters for a specific system.
In Chapter 3 comprehensive UV/Vis absorption datasets are presented for the dimerization of merocyanine derivative 1 in 1,4-dioxane, which allowed for the first time a direct comparison of the results derived from concentration-, temperature-, and solvent-dependent self-assembly studies.
The results for the binding constant K and corresponding G0 from the concentration- and temperature-dependent analysis were in very good agreement, also in comparison to the results from ITC. For the temperature-dependent analysis, though, multiple datasets of samples with different concentration had to be evaluated simultaneously to cover a meaningful part of the self-assembly process. Furthermore, a significant dependence of the optimized parameters H0 and S0 on the wavelength chosen for the analysis was observed. This can be rationalized by the small thermochromic shifts of both the monomer and the dimer UV/Vis absorption band. The results from the solvent-dependent evaluation showed the largest deviation, as expected for the highly solvatochromic merocyanine dye.
However, even here by evaluation at 491 and 549 nm the deviation for G0 was only 2.5 kJ mol1 (9%) with respect to the results from the concentration-dependent analysis (G0 = 29.1 kJ mol1). Thus, despite the strong solvatochromism of the dipolar chromophore, it can still be considered a reliable method for estimating the binding strength. Furthermore, multiple repetitions of the concentration-, temperature-, and solvent-dependent studies provided insight into the reproducibility of the results and possible sources of experimental errors. In all cases, the deviations of the results were small (G0 < 0.4 kJ mol1) and within the same range as the fit error from the nonlinear regression analysis.
The insights from these studies were an important basis for the in-depth investigation of a more complex supramolecular system in Chapter 4, as a single method is often not enough to capture the full picture of a more complicated self-assembly process. To elucidate the anti-cooperative self-assembly of the chiral merocyanine 2, a combination of multiple techniques had to be applied.
Solvent-dependent UV/Vis absorption studies in CH2Cl2/MCH mixtures showed the step-wise assembly of the merocyanine monomer (max(M) = 549 nm, CH2Cl2) to first a dimer (max(D) = 498 nm, CH2Cl2/MCH 15:85) by dipole-dipole interactions, and then a -stacked higher aggregate (max(H) = 477 nm, MCH), with pronounced H-type coupling.
The thermodynamic evaluation of this data, however, suffered from the severe solvatochromism, especially of the monomeric species (max(M, CH2Cl2) = 549 nm, max(M, MCH) = 596 nm). Therefore, concentration-dependent studies were performed at three different temperatures (298, 323, 353 K) to elucidate the self-assembly mechanism and determine reliable thermodynamic parameters. The studies at elevated temperatures were hereby necessary, to obtain experimental data over a larger agg--range. Due to the pronounced difference in the thermodynamic driving force for dimerization and higher aggregate formation (KD/K5 = 6500) a concentration range exists in MCH where almost exclusively the dimer species of 2 is present, before further self-assembly by dispersion interactions occurs. Therefore, the data could be evaluated independently for the two self-assembly steps. The self-assembly of dimers into the higher aggregate could not be described by the isodesmic model but was fitted satisfactorily to a pentamer model. This rather small size of about ten -stacked PYOP chromophores was, furthermore, consistently indicated by AFM, VPO and DOSY NMR measurements. Based on 1D and 2D NMR data as well as the strong bisignate CD signal of the higher aggregate in combination with TD-DFT calculations, a P-helical stack is proposed as its structure. The small size can be rationalized by the anti-cooperative self-assembly mechanism and the sterical demand of the solubilizing trialkoxyphenyl and the chiral tetralin substituents. Additionally, the aliphatic shell formed by the solubilizing chains around the polar chromophore stack, can account for the exceptionally high solubility of 2 in MCH (> 15 mg mL1). These combined studies of the self-assembly process enabled the identification of suitable conditions for the investigation of fluorescence properties of the individual aggregate species. Aggregation-induced emission enhancement was observed for the almost non-emissive monomer (Fl(M) = 0.23%), which can be rationalized by the increasing rigidification within the dimer (Fl(D) = 2.3%) and the higher aggregate (Fl(H) = 4.5%). The helical chirality of the PYOP decamer stack, furthermore, gave rise to a strong CPL signal with a large glum value of 0.011.
The important conclusion of this thesis is that the temperature- and solvent-dependent analyses are valid alternatives to the classical concentration-dependent analysis to determine thermodynamic parameters of self-assembly equilibria. Although, for a specific supramolecular system, one approach might be favourable over the others for a variety of reasons. The experimental limitations often demand a combination of techniques to fully elucidate a self-assembly process and to gain insights in the aggregate structure. The anti-cooperative merocyanine self-assembly, which was described here for the first time for the PYOP merocyanine 2, is no exception. Besides the interest in the merocyanine assemblies from a structural and functional point of view, the insights gained from the presented studies can also be transferred to other self-assembly systems and be a guide to find the most appropriate analysis technique.
This work aims at elucidating chemical processes involving homogeneous catalysis and photo–physical relaxation of excited molecules in the solid state. Furthermore, compounds with supposedly small singlet–triplet gaps and therefore biradicaloid character are investigated with respect to their electro–chemical behavior. The work on hydroboration catalysis via a reduced 9,10–diboraanthracene (DBA) was preformed in collaboration with the Wagner group in Frankfurt, more specifically Dr. Sven Prey, who performed all laboratory experiments. The investigation of delayed luminescence properties in arylboronic esters in their solid state was conducted in collaboration with the Marder group in Würzburg. The author of this work took part in the synthesis of the investigated compounds while being supervised by Dr. Zhu Wu. The final project was a collaboration with the group of Anukul Jana from Hyderabad, India who provided the experimental data.
Vitamin B6 deficiency has been linked to cognitive impairment in human brain disorders for decades. Still, the molecular mechanisms linking vitamin B6 to these pathologies remain poorly understood, and whether vitamin B6 supplementation improves cognition is unclear as well. Pyridoxal phosphatase (PDXP), an enzyme that controls levels of pyridoxal 5’-phosphate (PLP), the co-enzymatically active form of vitamin B6, may represent an alternative therapeutic entry point into vitamin B6-associated pathologies. However, pharmacological PDXP inhibitors to test this concept are lacking. We now identify a PDXP and age-dependent decline of PLP levels in the murine hippocampus that provides a rationale for the development of PDXP inhibitors. Using a combination of small molecule screening, protein crystallography and biolayer interferometry, we discover and analyze 7,8-dihydroxyflavone (7,8-DHF) as a direct and potent PDXP inhibitor. 7,8-DHF binds and reversibly inhibits PDXP with low micromolar affinity and sub-micromolar potency. In mouse hippocampal neurons, 7,8-DHF increases PLP in a PDXP-dependent manner. These findings validate PDXP as a druggable target. Of note, 7,8-DHF is a well-studied molecule in brain disorder models, although its mechanism of action is actively debated. Our discovery of 7,8-DHF as a PDXP inhibitor offers novel mechanistic insights into the controversy surrounding 7,8-DHF-mediated effects in the brain.
Die vorliegenden Texte sind die verschriftlichten und redigierten Beiträge eines internationalen Kolloquiums, das – organisiert von der École Pratique des Hautes Études, PSL, Paris, vom Institut für Kunstgeschichte der Universität Würzburg und der Universität Jaén – vom 1. bis 4. Juni 2022 in Paris stattfand und finanziell von der Deutsch-Französischen Hochschule unterstützt wurde.
After myocardial infarction, an inflammatory response is induced characterized by a sterile inflammation, followed by a reparative phase in order to induce cardiac healing. Neutrophils are the first immune cells that enter the ischemic tissue. Neutrophils have various functions in the ischemic heart, such as phagocytosis, production of reactive oxygen species or release of granule components. These functions can not only directly damage cardiac tissue, but are also necessary for initiating reparative effects in post-ischemic healing, indicating a dual role of neutrophils in cardiac healing after infarction.
In recent years, evidence has been growing that neutrophils show phenotypic and functional differences in distinct homeostatic and pathogenic settings.
Preliminary data of my working group using single-cell RNA-sequencing revealed the time- dependent heterogeneity of neutrophils, with different populations showing distinct gene expression profiles in ischemic hearts of mice, including the time-dependent appearance of a SiglecFhigh neutrophil population. To better understand the dynamics of neutrophil heterogeneity in the ischemic heart, my work aimed to validate previous findings at the protein level, as well as to investigate whether the distinct neutrophil populations show functional differences. Furthermore, in vivo depletion experiments were performed in order to modulate circulating neutrophil levels.
Hearts, blood, bone marrow and spleens were processed and analyzed from mice after 1 day and 3 days after the onset of cardiac ischemia and analyzed using flow cytometry.
Results showed that the majority of cardiac neutrophils isolated at day 3 after myocardial infarction were SiglecFhigh, whereas nearly no SiglecFhigh neutrophils could be isolated from ischemic hearts at day 1 after myocardial infarction.
No SiglecFhigh neutrophils could be found in the blood, spleen and bone marrow either after 1 day or 3 days after myocardial infarction, indicating that the SiglecFhigh state of neutrophils is unique to the ischemic cardiac tissue.
When I compared SiglecFhigh and SiglecFlow neutrophils regarding their phagocytosis activity and ROS production, SiglecFhigh neutrophils showed a higher phagocytosis ability than their SiglecFlow counterparts, as well as higher ROS production capacity.
In vivo depletion experiments could not achieve successful and efficient depletion of cardiac neutrophils either 1 day or 3 days after myocardial infarction, but led to a shift of a higher percentage of SiglecFhigh expressing neutrophils in the depletion group. Bone marrow neutrophil levels only showed partial depletion at day 3 after MI. Regarding blood neutrophils, depletion efficiently reduced circulating neutrophils at both time points, 1 and 3 days after MI. To summarize, this work showed the time-dependent presence of different neutrophil states in the ischemic heart. The main population of neutrophils isolated 3 days after MI showed a high expression of SiglecF, a unique state that could not be detected at different time points or other organs. These SiglecFhigh neutrophils showed functional differences regarding their phagocytosis ability and ROS production. Further investigation is needed to reveal what role these SiglecFhigh neutrophils could play within the ischemic heart.
To better target neutrophil depletion in vivo, more efficient or different anti-neutrophil strategies are needed.
Gold nanoparticles of diameter ca. 60 nm have been synthesized based on Turkevich and Frens protocols. We have demonstrated that the carboxyl-modified gold nanoparticles can be coupled covalently with antibodies (Ab) of interest using the EDC/NHS coupling procedure. Binding studies with Ab-grafted AuNPs and GpL fusion proteins proved that conjugation of AuNPs with antibodies enables immobilization of antibodies with preservation of a significant antigen binding capacity. More importantly, our findings showed that the conjugation of types of anti-TNF receptors antibodies such as anti-Fn14 antibodies (PDL192 and 5B6) (Aido et al., 2021), anti-CD40, anti-4-1BB and anti-TNFR2 with gold nanoparticles confers them with potent agonism. Thus, our results suggest that AuNPs can be utilized as a platform to immobilize anti-TNFR antibodies which, on the one hand, helps to enhance their agonistic activity in comparison to “free” inactive antibodies by mimicking the effect of cell-anchored antibodies or membrane-bound TNF ligands and, on the other hand, allows to develop new generations of drug delivery systems. These constructs are characterized with their biocompatibility and their tunable synthesis process.
In a further work part, we combined the benefits of the established system of Ab-AuNPs with materials used widely in the modern biofabrication approaches such as the photo-crosslinked hydrogels, methacrylate-modified gelatin (GelMA), combined with embedded variants of human cell lines. The acquired results demonstrated clearly that the attaching of proteins like antibodies to gold nanoparticles might reduce their release rate from the crosslinked hydrogels upon the very low diffusion of gold nanoparticles from the solid constructs to the surrounding medium yielding long-term local functioning proteins-attached particles. Moreover, our finding suggests that hydrogel-embedded AuNP-immobilized antibodies, e.g. anti-TNFα-AuNPs or anti-IL1-AuNPs enable local inhibitory functions,
To sum up, our results demonstrate that AuNPs can act as a platform to attach anti-TNFR antibodies to enhance their agonistic activity by resembling the output of cell-anchoring or membrane bounding. Gold nanoparticles are considered, thus, as promising tool to develop the next generation of drug delivery systems, which may contribute to cancer therapy. On top of that, the embedding of anti-inflammatory-AuNPs in the biofabricated hydrogel presents new innovative strategy of the treatment of autoinflammatory diseases.
Deep Learning (DL) models are trained on a downstream task by feeding (potentially preprocessed) input data through a trainable Neural Network (NN) and updating its parameters to minimize the loss function between the predicted and the desired output. While this general framework has mainly remained unchanged over the years, the architectures of the trainable models have greatly evolved. Even though it is undoubtedly important to choose the right architecture, we argue that it is also beneficial to develop methods that address other components of the training process. We hypothesize that utilizing domain knowledge can be helpful to improve DL models in terms of performance and/or efficiency. Such model-agnostic methods can be applied to any existing or future architecture. Furthermore, the black box nature of DL models motivates the development of techniques to understand their inner workings. Considering the rapid advancement of DL architectures, it is again crucial to develop model-agnostic methods.
In this thesis, we explore six principles that incorporate domain knowledge to understand or improve models. They are applied either on the input or output side of the trainable model. Each principle is applied to at least two DL tasks, leading to task-specific implementations. To understand DL models, we propose to use Generated Input Data coming from a controllable generation process requiring knowledge about the data properties. This way, we can understand the model’s behavior by analyzing how it changes when one specific high-level input feature changes in the generated data. On the output side, Gradient-Based Attribution methods create a gradient at the end of the NN and then propagate it back to the input, indicating which low-level input features have a large influence on the model’s prediction. The resulting input features can be interpreted by humans using domain knowledge.
To improve the trainable model in terms of downstream performance, data and compute efficiency, or robustness to unwanted features, we explore principles that each address one of the training components besides the trainable model. Input Masking and Augmentation directly modifies the training input data, integrating knowledge about the data and its impact on the model’s output. We also explore the use of Feature Extraction using Pretrained Multimodal Models which can be seen as a beneficial preprocessing step to extract useful features. When no training data is available for the downstream task, using such features and domain knowledge expressed in other modalities can result in a Zero-Shot Learning (ZSL) setting, completely eliminating the trainable model. The Weak Label Generation principle produces new desired outputs using knowledge about the labels, giving either a good pretraining or even exclusive training dataset to solve the downstream task. Finally, improving and choosing the right Loss Function is another principle we explore in this thesis. Here, we enrich existing loss functions with knowledge about label interactions or utilize and combine multiple task-specific loss functions in a multitask setting.
We apply the principles to classification, regression, and representation tasks as well as to image and text modalities. We propose, apply, and evaluate existing and novel methods to understand and improve the model. Overall, this thesis introduces and evaluates methods that complement the development and choice of DL model architectures.
Poor or variable oral bioavailability is of major concern regarding safety and efficacy for the treatment of patients with poorly water-soluble drugs (PWSDs). The problem statement of this work involves a pharmaceutical development perspective, the physicochemical basis of the absorption process and physiological / biopharmaceutical aspects. A methodology was developed aiming at closing the gap between drug liberation and dissolution on the one hand and the appearance of drug in the blood on the other. Considering what is out of control from a formulation development perspective, a clear differentiation between bioavailability and bioaccessibility was necessary. Focusing on the absorption process, bioaccessibility of a model compound, a poorly soluble but well permeable weak base, was characterized by means of flux across artificial biomimetic membranes. Such setups can be considered to reasonably mimic relevant oral absorption resistances in vitro in terms of diffusion through an unstirred water layer (UWL) and a lipidic barrier. Mechanistic understanding of the driving force for permeation was gained by differentiating drug species and subsequently linking them to the observed transfer rates using a bioaccessibility concept. The three key species that need to be differentiated are molecularly dissolved drug, drug associated in solution with other components (liquid reservoir) and undissolved drug (solid reservoir). An innovative approach to differentiate molecularly dissolved drug from the liquid reservoir using ultracentrifugation in combination with dynamic light scattering as control is presented. A guidance for rational formulation development of PWSDs is elaborated based on the employed model compound. It is structured into five guiding questions to help drug formulation scientists in selecting drug form, excipients and eventually the formulation principle. Overall, the relevance but also limitations of characterizing bioaccessibility were outlined with respect to practical application e.g. in early drug formulation development.
Hereditary spastic paraplegias (HSPs) are genetically-determined, neurodegenerative disorders characterized by progressive weakness and spasticity of the lower limbs. Spastic paraplegia type 11 (SPG11) is a complicated form of HSP, which is caused by mutations in the SPG11 gene encoding spatacsin, a protein possibly involved in lysosomal reformation. Based on our previous studies demonstrating that secondary neuroinflammation can be a robust amplifier of various genetically-mediated diseases of both the central and peripheral nervous system, we here test the possibility that neuroinflammation may modify the disease outcome also in a mouse model for SPG11. Spg11-knockout (Spg11-/-) mice develop early walking pattern and behavioral abnormalities, at least partially reflecting motor, and behavioral changes typical for patients. Furthermore, we detected a progressive increase in axonal damage and axonal spheroid formation in the white and grey matter compartments of the central nervous system of Spg11-/- mice. This was accompanied by a concomitant substantial increase of secondary inflammation by cytotoxic CD8+ and CD4+ T-lymphocytes. We here provide evidence that disease-related changes can be ameliorated/delayed by the genetic deletion of the adaptive immune system. Accordingly, we provide evidence that repurposing clinically approved immunomodulators (fingolimod/FTY720 or teriflunomide), that are in use for treatment of multiple sclerosis (MS), also improve disease symptoms in mice, when administered in an early (before neural damage) or late (after/during neural damage) treatment regime.
This work provides strong evidence that immunomodulation can be a therapeutic option for the still untreatable SPG11, including its typical neuropsychological features. This poses the question if inflammation is not only a disease amplifier in SPG11 but can act as a unifying factor also for other genetically mediated disorders of the CNS. If true, this may pave the way to therapeutic options in a wide range of still untreatable, primarily genetic, neurological disorders by repurposing approved immunomodulators.
This study investigates the sense of agency (SoA) for saccades with implicit and explicit agency measures. In two eye tracking experiments, participants moved their eyes towards on-screen stimuli that subsequently changed color. Participants then either reproduced the temporal interval between saccade and color-change (Experiment 1) or reported the time points of these events with an auditory Libet clock (Experiment 2) to measure temporal binding effects as implicit indices of SoA. Participants were either made to believe to exert control over the color change or not (agency manipulation). Explicit ratings indicated that the manipulation of causal beliefs and hence agency was successful. However, temporal binding was only evident for caused effects, and only when a sufficiently sensitive procedure was used (auditory Libet clock). This suggests a feebler connection between temporal binding and SoA than previously proposed. The results also provide evidence for a relatively fast acquisition of sense of agency for previously never experienced types of action-effect associations. This indicates that the underlying processes of action control may be rooted in more intricate and adaptable cognitive models than previously thought. Oculomotor SoA as addressed in the present study presumably represents an important cognitive foundation of gaze-based social interaction (social sense of agency) or gaze-based human-machine interaction scenarios.
Public significance statement: In this study, sense of agency for eye movements in the non-social domain is investigated in detail, using both explicit and implicit measures. Therefore, it offers novel and specific insights into comprehending sense of agency concerning effects induced by eye movements, as well as broader insights into agency pertaining to entirely newly acquired types of action-effect associations. Oculomotor sense of agency presumably represents an important cognitive foundation of gaze-based social interaction (social agency) or gaze-based human-machine interaction scenarios. Due to peculiarities of the oculomotor domain such as the varying degree of volitional control, eye movements could provide new information regarding more general theories of sense of agency in future research.
Expanding on a general equilibrium model of offshoring, we analyze the effects of a unilateral emissions tax increase on the environment, income, and inequality. Heterogeneous firms allocate labor across production tasks and emissions abatement, while only the most productive can benefit from lower labor and/or emissions costs abroad and offshore. We find a non-monotonic effect on global emissions, which decline if the initial difference in emissions taxes is small. For a sufficiently large difference, global emissions rise, implying emissions leakage of more than 100%. The underlying driver is a global technique effect: While the emissions intensity of incumbent non-offshoring firms declines, the cleanest firms start offshoring. Moreover, offshoring firms become dirtier, induced by a reduction in the foreign effective emissions tax in general equilibrium. Implementing a BCA prevents emissions leakage, reduces income inequality in the reforming country, but raises inequality across countries.
Besides their central role in haemostasis and thrombosis, platelets are increasingly recognised as versatile effector cells in inflammation, the innate and adaptive immune response, extracellular matrix reorganisation and fibrosis, maintenance of barrier and organ integrity, and host response to pathogens. These platelet functions, referred to as thrombo-inflammation and immunothrombosis, have gained major attention in the COVID-19 pandemic, where patients develop an inflammatory disease state with severe and life-threatening thromboembolic complications. In the CRC/TR 240, a highly interdisciplinary team of basic, translational and clinical scientists explored these emerging roles of platelets with the aim to develop novel treatment concepts for cardiovascular disorders and beyond. We have i) unravelled mechanisms leading to life-threatening thromboembolic complica-tions following vaccination against SARS-CoV-2 with adenoviral vector-based vaccines, ii) identified unrecognised functions of platelet receptors and their regulation, offering new potential targets for pharmacological intervention and iii) developed new methodology to study the biology of megakar-yocytes (MKs), the precursor cells of platelets in the bone marrow, which lay the foundation for the modulation of platelet biogenesis and function. The projects of the CRC/TR 240 built on the unique expertise of our research network and focussed on the following complementary fields: (A) Cell bi-ology of megakaryocytes and platelets and (B) Platelets as regulators and effectors in disease. To achieve this aim, we followed a comprehensive approach starting out from in vitro systems and animal models to clinical research with large prospective patient cohorts and data-/biobanking. Despite the comparably short funding period the CRC/TR 240 discovered basic new mechanisms of platelet biogenesis, signal transduction and effector function and identified potential MK/platelet-specific molecular targets for diagnosis and therapy of thrombotic, haemorrhagic and thrombo-inflammatory disease states.
Based on previous results showing that thioether modification of gold nanoparticles (AuNPs), especially coating with a multivalent system, yielded in excellent colloidal stability, the first aim of this thesis was to prove whether functionalization of silver nanoparticles (AgNPs) with thioether also has a comparable or even enhanced stabilization efficacy compared with the gold standard of coating with thiols and, particularly, whether the multivalency of polymers leads to stable AgNPs conjugates. Herein, AgNPs coated with mono- and multivalent thiol- and thioether polymers were prepared to systematically investigate the adsorption kinetics onto the silver surface as well as the colloidal stability after exposure to different conditions relevant for biomedical application. Although the thioether-polymers showed a slower immobilization onto AgNPs, same or mostly even better stabilization was exhibited than for the thiol analogs.
As multivalent thioether-poly(glycidol) (PG) is already proven as a promising candidate for AuNP modification and stabilization, the second aim of this thesis was to examine the stealth behavior of thioether-PG, side-chain functionalized with various hydrophobic (alkyl and cholesteryl) units, to gain a deeper understanding of AuNP surface functionalization in terms of protein adsorption and their subsequent cellular uptake by human monocyte-derived macrophages. For this purpose, citrate-stabilized AuNPs were modified with the amphiphilic polymers by ligand exchange reaction, followed by incubation in human serum. The various surface amphiphilicities affected protein adsorption to a certain extent, with less hydrophobic particle layers leading to a more inhibited protein binding. Especially AuNPs functionalized with PG carrying the longest alkyl chain showed differences in the protein corona composition compared to the other polymer-coated NPs. In addition, PGylation, and especially prior serum incubation, of the NPs exhibited reduced macrophage internalization.
As the use of mammals for in vivo experiments faces various challenges including increasing regulatory hurdles and costs, the third aim of this thesis was to validate larvae of the domestic silkworm Bombyx mori as an alternative invertebrate model for preliminary in vivo research, using AuNPs with various surface chemistry (one PEG-based modification and three PG-coatings with slightly hydrophobic functionalization, as well as positively and negatively charges) for studying their biodistribution and elimination. 6 h and 24 h after intra-hemolymph injection the Au content in different organ compartments was measured with ICP-MS, showing that positively charged particles appeared to be eliminated most rapidly through the midgut, while AuNPs modified with PEG, alkyl-functionalized PG and negatively charged PG exhibited long-term bioavailability in the silkworm body.
Komplementärmedizinische Angebote in der Onkologie erleben eine hohe Nachfrage. Diese Studie sollte klären, ob bei Patienten ein Mehrbedarf an ganzheitlichen, tagesklinischen Angeboten besteht. Im Rahmen dieser Fragebogen-basierten Analyse sollten Zielgruppen identifiziert werden, die besonders hiervon profitieren könnten. Mithilfe eines Fragebogens wurden zwischen 08/2019 und 10/2020 294 ambulant behandelte onkologische Patienten des Comprehensive Cancer Centers Mainfranken an der Universitätsklinik Würzburg befragt. Der Fragebogen ist angelehnt an das etablierte Curriculum Mind-Body-Medizin der Kliniken Essen-Mitte und umfasst zehn Untergruppen. Statistisch signifikante Zusammenhänge wurden durch Anwendung des Chi-Quadrat Tests ermittelt. In allen untersuchten Lebensbereichen fanden sich Hinweise auf einen Mehrbedarf an komplementärmedizinischen Angeboten. Ein Drittel der Patienten gab an, aus eigener Kraft keine überdauernden Lebensstiländerungen herbeiführen zu können. Das höchste Gesundheitsbewusstsein zeigte sich in den Bereichen Ernährung, Bewegung und Entspannung. Trotzdem führte ein Großteil der Befragten empfohlene Maßnahmen nicht durch. Insbesondere die Bereiche Schlaf, Energielevel und psychische Belastung wiesen das größte Verbesserungspotential auf. Defizite in diesen Bereichen beeinflussten sich gegenseitig und konnten mit Unzufriedenheit und negativen Gedanken sowie geringer Veränderungsmotivation in Verbindung gebracht werden. Besonders betroffen waren erwerbstätige Patienten im Alter zwischen 40-65 Jahren. Frauen zeigten sich deutlich motivierter als Männer komplementärmedizinische Angebote zu nutzen. Gemäß unseren Ergebnissen und evidenzbasierten Empfehlungen der S3-Leitlinie Komplementärmedizin ergibt sich ein Mehrbedarf nach folgenden Angeboten: Supervidierte Sportprogramme, MBSR, Tai Chi/ Qigong, individuelle Ernährungsberatung und Selbsthilfegruppen für Angehörige. Durch Vermittlung von Gesundheitsbewusstsein sollten insbesondere Patientengruppen motiviert werden, die aus eigener Kraft ihre Situation nicht verbessern können. Um den Erfolg von gesundheitsfördernden Lebensstiländerungen überdauernd zu sichern, ist weitere Unterstützung nötig.
Die Alveoläre Echinokokkose (AE) ist eine tödliche Infektionserkrankung, die durch den parasitären Plattwurm Echinococcus multilocularis verursacht wird. Genomanalysen von E. multilocularis ergaben ein Gen, das laut Vorhersage für eine DyP-Typ Peroxidase codiere. Ziel dieser Arbeit ist die biologische Funktion des codierten Enzyms besser zu verstehen und Hinweise auf eine mögliche Rolle in der Abwehr von Reaktiven Sauerstoffspezies (ROS) zu erlangen.
Das Gen wurde heterolog in E. Coli exprimiert und molekulare Charakteristika des Gens mit bioinformatischen und molekularbiologischen Methoden untersucht. Quantitative RT-PCR Untersuchungen gaben Aufschluss über das Transkriptprofil von emipox in unterschiedlichen Entwicklungsstadien von E. mulitlocularis. Mittels Whole-Mount In Situ-Hybridisierung (WMISH) wurden die Transkripte zudem lokalisiert und ihre Beziehung zum Stammzellsystem von E. multilocularis näher untersucht.
Die Zugehörigkeit von EmIPOX zur Gruppe der DyP-Typ Peroxidasen wurde bestätigt. Homologe beim Menschen kommen nicht vor. Es konnte nachgewiesen werden, dass Transkripte von emipox auch, aber keinesfalls ausschließlich, in Stammzellen vorliegen. Überdurchschnittlich viele Transkripte liegen im aktivierten Protoscolex und im Metacestoden ex vivo aus einer infizierten Wirtsleber vor. Untersuchungen zur Enzymaktivität von EmIPOX zeigten neben einer Peroxidase- auch eine Katalaseaktivität.
Die vorliegende Arbeit ist die erste Charakterisierung einer DyP-Typ Peroxidase bei Tieren. Sie legt nahe, dass EmIPOX eine Rolle in der Entgiftung von ROS in E. multilocularis spielt und stellt den Charakter von EmIPOX als potenzieller pharmakologischer Zielstruktur heraus.
Proteins fold in water and achieve a clear structure despite a huge parameter space. Inside a (protein) crystal you have everywhere the same symmetries as there is everywhere the same unit cell. We apply this to qubit interactions to do fundamental physics:
We modify cosmological inflation: we replace the big bang by a condensation event in an eternal all-encompassing ocean of free qubits. Rare interactions of qubits in the ocean provide a nucleus or seed for a new universe (domain), as the qubits become decoherent and freeze-out into defined bit ensembles. Next, we replace inflation by a crystallization event triggered by the nucleus of interacting qubits to which rapidly more and more qubits attach (like in everyday crystal growth). The crystal unit cell guarantees same symmetries (and laws of nature) everywhere inside the crystal, no inflation scenario is needed.
Interacting qubits solidify, quantum entropy decreases in the crystal, but increases outside in the ocean. The interacting qubits form a rapidly growing domain where the n**m states become separated ensemble states, rising long-range forces stop ultimately further growth. After this very early modified steps, standard cosmology with the hot fireball model takes over. Our theory agrees well with lack of inflation traces in cosmic background measurements.
Applying the Hurwitz theorem to qubits we prove that initiation of qubit interactions can only be 1,2,4 or 8-dimensional (agrees with E8 symmetry of our universe). Repulsive forces at ultrashort distances result from quantization, long-range forces limit crystal growth. The phase space of the crystal agrees with the standard model of the basic four forces for n quanta. It includes all possible ensemble combinations of their quantum states m, a total of n**m states. We describe a six-bit-ensemble toy model of qubit interaction and the repulsive forces of qubits for ultra-short distances. Neighbor states reach according to transition possibilities (S-matrix) with emergent time from entropic ensemble gradients. However, in our four dimensions there is only one bit overlap to neighbor states left (almost solid, only below Planck´s quantum is liquidity left). The E8 symmetry of heterotic string theory has six curled-up, small dimensions. These keep the qubit crystal together and never expand. We give energy estimates for free qubits vs bound qubits, misplacements in the qubit crystal and entropy increase during qubit crystal formation.
Implications are fundamental answers, e.g. why there is fine-tuning for life-friendliness, why there is string theory with rolled-up dimension and so many free parameters. We explain by cosmological crystallization instead of inflation the early creation of large-scale structure of voids and filaments, supercluster formation, galaxy formation, and the dominance of matter: the unit cell of our crystal universe has a matter handedness avoiding anti-matter. Importantly, crystals come and go in the qubit ocean. This selects for the ability to lay seeds for new crystals, for self-organization and life-friendliness. Vacuum energy gets appropriate low inside the crystal by its qubit binding energy, outside it is 10**20 higher. Scalar fields for color interaction/confinement and gravity could be derived from the qubit-interaction field.
In diesem Beitrag wird zunächst das Konzept des digital storytelling mit dem Tablet im frühen Fremdsprachenunterricht methodisch-didaktisch gerahmt (Kapitel 1). Daran anschließend wird die Bedeutung lernunterstützender Maßnahmen in einem solchen digital gestützten und potenziell kreativitätsfördernden Unterrichtssetting erläutert (Kapitel 2). In Kapitel 3 folgt die Vorstellung der Unterrichtsreihe „It’s storytime – Let’s create our own digital fairy tale“. Im Verlauf dieser Unterrichtsreihe, die auch als Projektwoche angelegt werden kann, rezipieren die Schüler:innen zunächst eigenständig Märchen in englischer Sprache, die aus dem deutschen und angloamerikanischen Sprachraum bekannt sind. Die Märchen liegen für das Tablet multimedial aufbereitet vor. Anschließend entwickeln die Lernenden auf Grundlage des erarbeiteten gattungsspezifischen Wortschatzes ein eigenes multimediales Märchen. Alle für die Unterrichtsreihe benötigten digitalen und analogen Materialien stehen als Download zur Verfügung und können für den eigenen Unterricht genutzt und adaptiert werden.
1,1,2-trifluoroethene (HFO-1123) is intended for use as a refrigerant. Inhalation studies on HFO-1123 in rats suggested a low potential for toxicity, with no-observed-adverse-effect levels greater then 20,000 ppm. However, single inhalation exposure of Goettingen Minipigs and New Zealand White Rabbits resulted in mortality. It was assumed that conjugation of HFO-1123 with glutathione, via glutathione S-transferase, gives rise to S-(1,1,2-trifluoroethyl)-L-glutathione (1123-GSH), which is then transformed to the corresponding cysteine S-conjugate (S-(1,1,2-trifluoroethyl)-L-cysteine, 1123-CYS). Subsequent beta-lyase mediated cleavage of 1123-CYS may result in monofluoroacetic acid, a potent inhibitor of aconitase. Species-differences in 1123-GSH formation and 1123-CYS cleavage to MFA may explain species-differences in HFO-1123 toxicity.
This study was designed to test the hypothesis, that GSH-dependent biotransformation and subsequent beta-lyase mediated formation of monofluoroacetic acid, a potent inhibitor of aconitase in the citric acid cycle, may play a key role in HFO-1123 toxicity and to evaluate if species-differences in the extent of MFA formation may account for the species-differences in HFO-1123 toxicity. The overall objective was to determine species-differences in HFO-1123 biotransformation in susceptible vs. less susceptible species and humans as a basis for human risk assessment.
To this end, in vitro biotransformation of HFO-1123 and 1123-CYS was investigated in renal and hepatic subcellular fractions of mice, rats, humans, Goettingen Minipigs and NZW Rabbits. Furthermore, cytotoxicity and metabolism of 1123-CYS was assessed in cultured renal epithelial cells. Enzyme kinetic parameters for beta-lyase mediated cleavage of 1123-CYS in renal and hepatic cytosolic fractions were determined, and 19F-NMR was used to identify fluorine containing metabolites arising from 1123-CYS cleavage. Quantification of 1123-GSH formation in hepatic S9 fractions after incubation with HFO-1123 was performed by LC-MS/MS and hepatic metabolism of HFO-1123 was monitored by 19F-NMR.
Rates of 1123-GSH formation were increased in rat, mouse and NZW Rabbit compared to human and Goettingen hepatic S9, indicating increased GSH dependent biotransformation in rats, mouse and NZW Rabbits. NZW Rabbit hepatic S9 exhibited increased 1123-GSH formation in the presence compared to the absence of acivicin, a specific gamma-GT inhibitor. This indicates increased gamma-GT mediated cleavage of 1123-GSH in NZW Rabbit hepatic S9 compared to the other species. 19F-NMR confirmed formation of 1123-GSH as the main metabolite of GSH mediated biotransformation of HFO-1123 in hepatic S9 fractions next to F-. Increased F- formation was detected in NZW Rabbit and Goettingen Minipig hepatic S9 in the presence of an NADPH regenerating system, indicating a higher rate of CYP-450 mediated metabolism in these species. Based on these findings, it is possible that CYP-450 mediated metabolism may contribute to HFO-1123 toxicity.
In contrast to the increased formation of 1123-GSH in rat, mouse and NZW Rabbit hepatic S9 (compared to human and Goettingen Minipig), enzyme kinetic studies revealed a significantly higher beta-lyase activity towards 1123-CYS in renal cytosol of Goettingen Minipigs compared to cytosol from rats, mice, humans and NZW Rabbits. However, beta-lyase cleavage in renal NZW Rabbit cytosol was slightly increased compared to rat, mouse and human renal cytosols. 19F-NMR analysis confirmed increased time-dependent formation of MFA in renal Goettingen Minipig cytosol and NZW Rabbit (compared to human and rat cytosolic fractions). Three structurally not defined MFA-derivatives were detected exclusively in NZW Rabbit and Goettingen Minipig cytosols. Also, porcine kidney cells were more sensitive to cytotoxicity of 1123-CYS compared to rat and human kidney cells.
Overall, increased beta-lyase mediate cleavage of 1123-CYS to MFA in Goettingen Minipig and NZW Rabbit kidney (compared to human and rat) may support the hypothesis that enzymatic cleavage by beta-lyases may account for the species-differences in HFO-1123 toxicity. However, the extent of GST mediated biotransformation in the liver as the initial step in HFO-1123 metabolism does not fully agree with this hypothesis, since 1123-GSH formation occurs at higher rates in rat, mouse and NZW Rabbit S9 as compared to the Goettingen Minipig.
Based on the inconsistencies between the extent of GST and beta-lyase mediated biotransformation of HFO-1123 obtained by this study, a decisive statement about an increased biotransformation of HFO-1123 in susceptible species with a direct linkage to the species-specific toxicity cannot be drawn. Resulting from this, a clear and reliable conclusion regarding the risk for human health originating from HFO-1123 cannot be made. However, considering the death of Goettingen Minipigs and NZW Rabbits after inhalation exposure of HFO-1123 at concentrations great than 500 ppm and greater than 1250 ppm, respectively, this indicates a health concern for humans under peak exposure conditions. For a successful registration of HFO-1123 and its use as a refrigerant, further in vitro and in vivo investigations addressing uncertainties in the species-specific toxicity of HFO-1123 are urgently needed.
In vitro models mimic the tissue-specific anatomy and play essential roles in personalized medicine and disease treatments. As a sophisticated manufacturing technology, 3D printing overcomes the limitations of traditional technologies and provides an excellent potential for developing in vitro models to mimic native tissue. This thesis aims to investigate the potential of a high-resolution 3D printing technology, melt electrowriting (MEW), for fabricating in vitro models. MEW has a distinct capacity for depositing micron size fibers with a defined design. In this thesis, three approaches were used, including 1) extending the MEW polymer library for different biomedical applications, 2) developing in vitro models for evaluation of cell growth and migration toward the different matrices, and 3) studying the effect of scaffold designs and biochemical cues of microenvironments on cells.
First, we introduce the MEW processability of (AB)n and (ABAC)n segmented copolymers, which have thermally reversible network formulation based on physical crosslinks. Bisurea segments are combined with hydrophobic poly(dimethylsiloxane) (PDMS) or hydrophilic poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEG-PPO) segments to form the (AB)n segmented copolymers. (ABAC)n segmented copolymers contain all three segments: in addition to bisurea, both hydrophobic and hydrophilic segments are available in the same polymer chain, resulting in tunable mechanical and biological behaviors. MEW copolymers either support cells attachment or dissolve without cytotoxic side effects when in contact with the polymers at lower concentrations, indicating that this copolymer class has potential in biological applications. The unique biological and surface properties, transparency, adjustable hydrophilicity of these copolymers could be beneficial in several in vitro models.
The second manuscript addresses the design and development of a melt electrowritten competitive 3D radial migration device. The approach differs from most of the previous literature, as MEW is not used here to produce cell invasive scaffolds but to fabricate an in vitro device. The device is utilized to systematically determine the matrix which promotes cell migration and growth of glioblastoma cells. The glioblastoma cell migration is tested on four different Matrigel concentrations using a melt electrowritten radial device. The glioblastoma U87 cell growth and migration increase at Matrigel concentrations 6 and 8 mg mL-1 In the development of this radial device, the accuracy, and precision of melt electrowritten circular shapes were investigated. The results show that the printing speed and design diameter are essential parameters for the accuracy of printed constructs. It is the first instance where MEW is used for the production of in vitro devices.
The influence of biochemical cues and scaffold designs on astrocytes and glioblastoma is investigated in the last manuscript. A fiber comprising the box and triangle-shaped pores within MEW scaffolds are modified with biochemical cues, including RGD and IKVAV peptides using a reactive NCO-sP(EO-stat-PO) macromer. The results show that astrocytes and glioblastoma cells exhibit different phenotypes on scaffold designs and peptide-coated scaffolds.
Safety and tolerability of SGLT2 inhibitors in cardiac amyloidosis — a clinical feasibility study
(2024)
Sodium-glucose transport protein 2 inhibitors (SGLT2i) slow the progression of renal dysfunction and improve the prognosis of patients with heart failure. Amyloidosis constitutes an important subgroup for which evidence is lacking. Amyloidotic fibrils originating from misfolded transthyretin and light chains are the causal agents in ATTR and AL amyloidosis. In these most frequent subtypes, cardiac involvement is the most common organ manifestation. Because cardiac and renal function frequently deteriorate over time, even under best available treatment, SGLT2i emerge as a promising treatment option due to their reno- and cardioprotective properties. We retrospectively analyzed patients with cardiac amyloidosis, who received either dapagliflozin or empagliflozin. Out of 79 patients, 5.1% had urinary tract infections; 2 stopped SGLT2i therapy; and 2.5% died unrelated to the intake of SGLT2i. No genital mycotic infections were observed. As expected, a slight drop in the glomerular filtration rate was noted, while the NYHA functional status, cardiac and hepatic function, as well as the 6 min walk distance remained stable over time. These data provide a rationale for the use of SGLT2i in patients with amyloidosis and concomitant cardiac or renal dysfunction. Prospective randomized data are desired to confirm safety and to prove efficacy in this increasingly important group of patients.
We analyze the mathematical models of two classes of physical phenomena. The first class of phenomena we consider is the interaction between one or more insulating rigid bodies and an electrically conducting fluid, inside of which the bodies are contained, as well as the electromagnetic fields trespassing both of the materials. We take into account both the cases of incompressible and compressible fluids. In both cases our main result yields the existence of weak solutions to the associated system of partial differential equations, respectively. The proofs of these results are built upon hybrid discrete-continuous approximation schemes: Parts of the systems are discretized with respect to time in order to deal with the solution-dependent test functions in the induction equation. The remaining parts are treated as continuous equations on the small intervals between consecutive discrete time points, allowing us to employ techniques which do not transfer to the discretized setting. Moreover, the solution-dependent test functions in the momentum equation are handled via the use of classical penalization methods.
The second class of phenomena we consider is the evolution of a magnetoelastic material. Here too, our main result proves the existence of weak solutions to the corresponding system of partial differential equations. Its proof is based on De Giorgi's minimizing movements method, in which the system is discretized in time and, at each discrete time point, a minimization problem is solved, the associated Euler-Lagrange equations of which constitute a suitable approximation of the original equation of motion and magnetic force balance. The construction of such a minimization problem is made possible by the realization that, already on the continuous level, both of these equations can be written in terms of the same energy and dissipation potentials. The functional for the discrete minimization problem can then be constructed on the basis of these potentials.
mRNA is co- or post-transcriptionally processed from a precursor mRNA to a mature mRNA. In addition to 5'capping and splicing, these modifications also include polyadenylation, the addition of a polyA tail to the 3'end of the mRNA. In recent years, alternative polyadenylation in particular has increasingly been taken into account as a mechanism for regulating gene expression. It is assumed that approximately 70-75 % of human protein coding genes contain alternative polyadenylation signals, which are often located within intronic sequences of protein-coding genes. The use of such polyadenylation signals leads to shortened mRNA transcripts and thus to the generation of C-terminal shortened protein isoforms.
Interestingly, the majority of microRNAs, small non-coding RNAs that play an essential role in post-transcriptional gene regulation, are also encoded in intronic sequences of protein-coding genes and are co-transcriptionally expressed with their host genes. The biogenesis of microRNA has been well studied and is well known, but mechanisms that may influence the expression regulation of mature microRNAs are just poorly understood.
In the presented work, I aimed to investigate the influence of alternative intronic polyadenylation on the biogenesis of microRNAs. The human ion channel TRPM1 could already be associated with melanoma pathogenesis and truncated isoforms of this protein have already been described in literature. In addition, TRPM1 harbors a microRNA, miR211, in its sixth intron, which is assumed to act as a tumor suppressor. Since both, TRPM1 and miR211 have already been associated with melanoma pathogenesis, the shift towards truncated transcripts during the development of various cancers is already known and it has been shown that certain microRNAs play a crucial role in the development and progression of melanoma, melanoma cell lines were used as an in vitro model for these investigations.
Development Of A Human iPSC-Derived Cortical Neuron Model Of Adaptor- Protein-Complex-4-Deficiency
(2024)
Adaptor-protein-4-deficiency (AP-4-deficiency) is an autosomal-recessive childhood- onset form of complicated hereditary spastic paraplegia (HSP) caused by bi-allelic loss- of-function mutations in one of the four subunits of the AP-4-complex. These four conditions are named SPG47 (AP4B1, OMIM #614066), SPG50 (AP4M1, OMIM #612936), SPG51 (AP4E1, OMIM #613744) and SPG52 (AP4S1, OMIM #614067), respectively and all present with global developmental delay, progressive spasticity and seizures. Imaging features include a thinning of the corpus callosum, ventriculomegaly and white matter changes. AP-4 is a highly conserved heterotetrameric complex, which is responsible for polarized sorting of transmembrane cargo including the autophagy- related protein 9 A (ATG9A). Loss of any of the four subunits leads to an instable complex and defective sorting of AP-4-cargo. ATG9A is implicated in autophagosome formation and neurite outgrowth. It is missorted in AP-4-deficient cells and CNS-specific knockout of Atg9a in mice results in a phenotype reminiscent of AP-4-deficiency. However, the AP-4-related cellular phenotypes including ATG9A missorting have not been investigated in human neurons.
Thus, the aim of this study is to provide the first human induced pluripotent stem cell- derived (iPSC) cortical neuron model of AP-4-deficiency to explore AP-4-related phenotypes in preparation for a high-content screening. Under the hypothesis that AP-4- deficiency leads to ATG9A missorting, elevated ATG9A levels, impaired autophagy and neurite outgrowth in human iPSC-derived cortical neurons, in vitro biochemical and imaging assays including automated high-content imaging and analysis were applied. First, these phenotypes were investigated in fibroblasts from three patients with compound heterozygous mutations in the AP4B1 gene and their sex-matched parental controls. The same cell lines were used to generate iPSCs and differentiate them into human excitatory cortical neurons.
This work shows that ATG9A is accumulating in the trans-Golgi-network in AP-4- deficient human fibroblasts and that ATG9A levels are increased compared to parental controls and wild type cells suggesting a compensatory mechanism. Protein levels of the AP4E1-subunit were used as a surrogate marker for the AP-4-complex and were decreased in AP-4-deficient fibroblasts with co-immunoprecipitation confirming the instability of the complex. Lentiviral re-expression of the AP4B1-subunit rescues this corroborating the fact that a stable AP-4-complex is needed for ATG9A trafficking. Surprisingly, autophagic flux was present in AP-4-deficient fibroblasts under nutrient- rich and starvation conditions. These phenotypic markers were evaluated in iPSC-derived cortical neurons and here, a robust accumulation of ATG9A in the juxtanuclear area was seen together with elevated ATG9A protein levels. Strikingly, assessment of autophagy markers under nutrient-rich conditions showed alterations in AP-4-deficient iPSC- derived cortical neurons indicating dysfunctional autophagosome formation. These findings point towards a neuron-specific impairment of autophagy and need further investigation. Adding to the range of AP-4-related phenotypes, neurite outgrowth and branching are impaired in AP-4-deficient iPSC-derived cortical neurons as early as 24h after plating and together with recent studies point towards a distinct role of ATG9A in neurodevelopment independent of autophagy.
Together, this work provides the first patient-derived neuron model of AP-4-deficiency and shows that ATG9A is sorted in an AP-4-dependent manner. It establishes ATG9A- related phenotypes and impaired neurite outgrowth as robust markers for a high-content screening. This disease model holds the promise of providing a platform to further study AP-4-deficiency and to search for novel therapeutic targets.
Die Erforschung viraler Proteine ist wichtig, um virale Infektionen besser verstehen und
damit therapieren zu können. Die Aufklärung der DUB-Funktion auf dem viralen
Herpesprotein pUL36 ermöglicht ein besseres Verständnis des Infektionshergangs und
könnte zur Entwicklung eines Enzyminhibitors führen, der nur an diesem Enzym ansetzt,
nachdem es sich von den zellulären DUBs unterscheidet (Kattenhorn et al., 2005). In
dieser Arbeit konnten die vorherigen Daten, die eine stärkere Hemmung der DUB-
Mutante unter Interferoneinfluss zeigten, in unterschiedlichen Assay-Designs bestätigt
werden. Auch Versuche mit einem anderen Herpes simplex Virus Strang, bestätigten die
vorherigen Daten. Die Ergebnisse zeigen, dass die DUB-Funktion für HSV-1 wichtig ist für
die virale Evasion der zellulären Immunantwort. Die genaue Funktion der DUB in der
Infektion ist jedoch unklar. Aufgrund der vorbestehenden Datenlage erschien am
wahrscheinlichsten, dass die DUB-Funktion vor Eindringen des Herpes Simplex Virus in
den Zellkern zum Tragen kommt, womit es nach Abnahme des Interferons nicht zu einer
viralen Reaktivierung käme. Deshalb wurden Untersuchungen unternommen, um eine
mögliche Reaktivierung nach Abnahme des Interferons näher zu untersuchen. Hierfür
wurden zwei verschiedene Experimente entwickelt. Einmal wurde das Interferon direkt
nach Infektion und einmal 3 Tage nach Infektion (3dpi) abgenommen. Die Ergebnisse
zeigten beide eine stärkere Hemmung der DUB-HSV-1-Mutante unter Interferoneinfluss.
Bei Abnahme des Interferons direkt nach Infektion lag bei Wildtyp und Mutante ein
leichter Anstieg der Plaquezahlen vor, wobei dieser Effekt von der Dosis des Interferons
abhängig war. Eine hohe Interferondosis begünstigte bei beiden eine stärkere Hemmung,
allerdings bei beiden auch eine leichte Erhöhung der Plaquezahl nach Abnahme. Bei
einer niedrigen Dosis konnte nur eine stärkere Hemmung der DUB-Mutante, jedoch
keine Reaktivierung bei Wildtyp und Mutante nach Abnahme des Interferons gezeigt
werden. Bei Abnahme drei Tage nach Infektion zeigte sich sowohl bei dem Wildtyp-Virus
als auch der DUB- Mutante kein Anstieg in den Plaquezahlen. Es sind, nachdem
Deubiquitinierung nicht nur eine Rolle in der Verhinderung des proteosomalen Abbaus
von in die Zelle eingedrungenem Virus spielt, sondern auch der Zellregulation, mehrere
Szenarien denkbar, die diesen Phänotyp erklären könnten. Die DUB-Funktion könnte
zwar den proteosomalen Abbau durch Deubiqutinierung und damit Verhinderung der
Markierung des Virus zum zellulären Abbau verhindern. Allerdings könnten sich durch
einen langsameren Transport aus der Zelle oder in den Nucleus auch weniger Plaques
bei der Mutante als wie beim Wildtyp unter Interferoneinfluss bilden, nachdem das Virus
dann leichter Ziel antiviraler Proteine werden könnte. Oder die DUB-Funktion spielt eine
Rolle beim Eintritt in den Kern durch Modifikationen anderer Proteine. Virengenome
könnten auch durch eine fehlende DUB-Funktion reprimiert werden oder die Zelle durch
Apoptose absterben. Interessanterweise konnte keine Hemmung der DUB-Mutante in
Interferon behandelten U-2 OS Zellen gezeigt werden, von denen ein Defekt im STING-
vermittelten Signalweg bekannt ist. Vielleicht zeigt dies, dass das STING-Protein an dem
gezeigten DUB-Phänotyp beteiligt ist. Nachgewiesen ist außerdem bereits eine Funktion
des Enzyms bei der zweiten Umhüllung der Kapside bei Pseudorabiesvirus (Möhl, 2011).
Weitere Untersuchungen unter Einsatz bspw. von Immunfluoreszenz,
Proteasominhibitoren oder weiteren Zelllinien wie Saos-2, sind nötig, um die genaue
Funktion zu klären.
The Western Honeybee (Apis mellifera) is among the most versatile species in the world. Its adaptability is rooted in thousands of the differently specialized individuals acting jointly together. Thus, bees that are able to handle a certain task or condition well can back up other individuals less capable to do so on the colony level. Vice versa, the latter individuals might perform better in other situations. This evolutionary recipe for success ensures the survival of colonies despite challenging habitat conditions. In this context, the ectoparasitic mite Varroa destructor reflects the most pronounced biotic challenge to honeybees worldwide. Without proper treatment, infested colonies rapidly dwindle and ultimately die. Nevertheless, resistance behaviours against this parasite have evolved in some populations through natural selection, enabling colonies to survive untreated. In this, different behaviours appear to be adapted to the respective habitat conditions and may complement each other. Yet, the why and how of this behavioural response to the mite remains largely unknown. My thesis focuses on the biological background of Varroa-resistance traits in honeybees and presents important findings for the comprehension of this complex host-parasite interaction. Based on this, I draw implications for both, applied bee breeding and scientific investigations in the field of Varroa-resistance. Specifically, I focus on two traits commonly found in resistant and, to a lower degree, also mite-susceptible colonies: decreased mite reproduction and the uncapping and subsequent recapping of sealed brood cells. Examining failures in the reproductive success of mites as a primary mechanism of Varroa-resistance, I was able to link them to specific bee behaviours and external factors. Since mite reproduction and the brood rearing of bees are inevitably connected, I first investigated the effects of brood interruption on the reproductive success of mites. Brood interruption decreased the reproductive success of mites both immediately and in the long term. By examining the causes of reproductive failure, I could show that this was mainly due to an increased share of infertile mites. Furthermore, I proved that interruption in brood rearing significantly increased the expression of recapping behaviour. These findings consequently showed a dynamic modulation of mite reproduction and recapping, as well as a direct effect of brood interruption on both traits. To further elucidate the plasticity in the expression of both traits, I studied mite reproduction, recapping behaviour and infestation levels over the course of three years. The resulting extensive dataset unveiled a significant seasonal variation in mite reproduction and recapping. In addition, I show that recapping decreases the reproductive success of mites by increasing delayed developing female offspring and cells lacking male offspring. By establishing a novel picture-based brood investigation method, I could furthermore show that both the removal of brood cells and recapping activity specifically target brood ages in which mite offspring would be expected. Recapping, however, did not cause infertility of mites. Considering the findings of my first study, this points towards complementary mechanisms.
This underlines the importance of increased recapping behaviour and decreased mite reproduction as resistance traits, while at the same time emphasising the challenges of reliable data acquisition. To pave the way for a practical application of these findings in breeding, we then investigated the heritability (i.e., the share of genotypic variation on the observed phenotypic variation) of the accounted traits. By elaborating comparable test protocols and compiling data from over 4,000 colonies, we could, for the first time, demonstrate that recapping of infested cells and decreased reproductive success of mites are heritable (and thus selectable) traits in managed honeybee populations.
My thesis proves the importance of recapping and decreased mite reproduction as resistance traits and therefore valuable goals for breeding efforts. In this regard, I shed light on the underlying mechanisms of both traits, and present clear evidence for their interaction and heritability.
The expression of the MYC proto-oncogene is elevated in a large proportion of patients with pancreatic ductal adenocarcinoma (PDAC). Previous findings in PDAC have shown that this increased MYC expression mediates immune evasion and promotes S-phase progression. How these functions are mediated and whether a downstream factor of MYC mediates these functions has remained elusive. Recent studies identifying the MYC interactome revealed a complex network of interaction partners, highlighting the need to identify the oncogenic pathway of MYC in an unbiased manner.
In this work, we have shown that MYC ensures genomic stability during S-phase and prevents transcription-replication conflicts. Depletion of MYC and inhibition of ATR kinase showed a synergistic effect to induce DNA damage. A targeted siRNA screen targeting downstream factors of MYC revealed that PAF1c is required for DNA repair and S-phase progression. Recruitment of PAF1c to RNAPII was shown to be MYC dependent. PAF1c was shown to be largely dispensable for cell proliferation and regulation of MYC target genes.
Depletion of CTR9, a subunit of PAF1c, caused strong tumor regression in a pancreatic ductal adenocarcinoma model, with long-term survival in a subset of mice. This effect was not due to induction of DNA damage, but to restoration of tumor immune surveillance.
Depletion of PAF1c resulted in the release of RNAPII with transcription elongation factors, including SPT6, from the bodies of long genes, promoting full-length transcription of short genes. This resulted in the downregulation of long DNA repair genes and the concomitant upregulation of short genes, including MHC class I genes. These data demonstrate that a balance between long and short gene transcription is essential for tumor progression and that interference with PAF1c levels shifts this balance toward a tumor-suppressive transcriptional program. It also directly links MYC-mediated S-phase progression to immune evasion. Unlike MYC, PAF1c has a stable, known folded structure; therefore, the development of a small molecule targeting PAF1c may disrupt the immune evasive function of MYC while sparing its physiological functions in cellular growth.
Ziel der vorliegenden Studie war es zu untersuchen, ob anhand geometrischer Merkmale der HWK im Kindesalter eine sichere individuelle Vorhersage der Morphologie der HWK zum Ende der Entwicklung möglich ist. Hierdurch könnte eine Individualisierung der CVM-Methode und somit eine Einschätzung des bereits verstrichenen Wachstums erfolgen.
Zu diesem Zweck wurden insgesamt 1377 FRS-Aufnahmen von 267 Patienten – 110 weibliche und 157 männliche – aus dem Archiv der Poliklinik für Kieferorthopädie des Universitätsklinikums Würzburg digitalisiert und untersucht. Die HWK wurden im Programm OnyxCeph (Herst.: Image Instruments GmbH) quantifiziert und die berechneten Werte mit der Software SPSS statistisch ausgewertet. Mittels linearer Regressionen wurde versucht, anhand der Morphologie der Wirbelkörper vor dem puberalen Wachstumsschub auf die Geometrie der HWK im Erwachsenenalter zu schließen. Zur Illustrierung wurden Streudiagramm und die dazugehörigen Abfolgen von Röntgenbildern dargestellt.
Eine Schätzung der Geometrie der HWK im Erwachsenenalter würde bei den separat betrachteten Parametern und bei einer gemeinsamen Betrachtung der Parameter kaum zu korrekten Einschätzungen führen.
Die Streudiagramme mit den Bilderabfolgen stützen diese These ebenfalls und illustrieren die mögliche Fehleinschätzung der Geometrie.
Die Ergebnisse der Studie zeigen erneut, dass die Geometrie der HWK im Erwachsenenalter sehr variabel ist, wie komplex die Entwicklung der HWK ist und dass anhand ihrer Geometrie im Kindesalter keine sichere Einschätzung der skelettalen Reife möglich ist.
Eine Individualisierung der CVM-Methode ist anhand der in dieser Studie untersuchten Parameter nicht möglich. Somit lässt sich schlussfolgern, dass die CVM-Methode nicht als alleinige Methode zur präzisen skelettalen Alterseinschätzung verlässlich genutzt werden kann, sondern für eine sichere Beurteilung weitere Reifeindikatoren hinzugezogen werden sollten. Allerdings sollten hierzu zusätzliche radiologische Untersuchungen, wie beispielsweise die Handröntgenaufnahme, nur dann durchgeführt werden, wenn diese dem ALARA-Prinzip entsprechen.
The immune system is responsible for the preservation of homeostasis whenever a given organism is exposed to distinct kinds of perturbations. Given the complexity of certain organisms like mammals, and the diverse types of challenges that they encounter (e.g. infection or disease), the immune system evolved to harbor a great variety of distinct immune cell populations with specialized functions. For instance, the family of T cells is sub-divided into conventional (Tconv) and unconventional T cells (UTCs). Tconv form part of the adaptive arm of the immune system and are comprised of αβ CD4+ or CD8+ cells that differentiate from naïve to effector and memory populations upon activation and are essential during infection and cancer. Furthermore, UTCs, which include γδ T cells, NKT and MAIT, are involved in innate and adaptive immune responses, due to their dual mode of activation, through cytokines (innate-like) or TCR (adaptive), and function. Despite our understanding of the basic functions of T cells in several contexts, a great number of open questions related to their basic biology remain. For instance, the mechanism behind the differentiation of naïve CD4+ and CD8+ T cells into effector and memory populations is not fully understood. Moreover, the exact function and relevance of distinct UTC subpopulations in a physiological context have not been fully clarified. Here, we investigated the factors mediating naïve CD8+ T cell differentiation into effector and memory cells. By using flow cytometry, mass spectrometry, enzymatic assays, and transgenic mouse models, we found that the membrane bound enzyme sphingomyelin-phosphodiesterase acid-like 3b (Smpdl3b) is crucial for the maintenance of memory CD8+ T cells. Our data show that the absence of Smpdl3b leads to diminished CD8+ T cell memory, and a loss of stem-like memory populations due to an aggravated contraction. Our scRNA-seq data suggest that Smpdl3b could be involved in clathrinmediated endocytosis through modulation of Huntingtin interacting protein 1 (Hip1) levels, likely regulating TCR-independent signaling events. Furthermore, in this study we explored the role of UTCs in lymph node-specific immune responses. By using transgenic mouse models for photolabeling, lymph node transplantation models, infection models and flow cytometry, we demonstrate that S1P regulates the migration of tissue-derived UTC from tissues to draining lymph nodes, resulting in heterogeneous immune responses mounted by lymph nodes draining different tissues. Moreover, our unbiased scRNAseq and single lineage-deficient mouse models analysis revealed that all UTC lineages (γδ T cells, NKT and MAIT) are organized in functional units, based on transcriptional homogeneity, shared microanatomical location and migratory behavior, and numerical and functional redundancy. Taken together, our studies describe additional cell intrinsic (Smpdl3b) and extrinsic (S1Pmediated migration) functions of sphingolipid metabolism modulating T cell biology. We propose the S1P/S1PR1/5 signaling axis as the potential survival pathway for Smpdl3b+ memory CD8+ T cells and UTCs, mainly in lymph nodes. Possibly, Smpdl3b regulates S1P/S1PR signaling by balancing ligandreceptor endocytosis, while UTCs migrate to lymph nodes during homeostasis to be exposed to specific levels of S1P that assure their maintenance. Our results are clinically relevant, since several drugs modulating the S1P/S1PR signaling axis or the levels of Smpdl3b are currently used to treat human diseases, such as multiple sclerosis and B cell-mediated diseases. We hope that our discoveries will inspire future studies focusing on sphingolipid metabolism in immune cell biology.
To grow larger, insects must shed their old rigid exoskeleton and replace it with a new one. This process is called molting and the motor behavior that sheds the old cuticle is called ecdysis. Holometabolic insects have pupal stages in between their larval and adult forms, during which they perform metamorphosis. The pupal stage ends with eclosion, i.e., the emergence of the adult from the pupal shell. Insects typically eclose at a specific time during the day, likely when abiotic conditions are at their optimum. A newly eclosed insect is fragile and needs time to harden its exoskeleton. Hence, eclosion is regulated by sophisticated developmental and circadian timing mechanisms.
In Drosophila melanogaster, eclosion is limited to a daily time window in the morning, regarded as the “eclosion gate”. In a population of laboratory flies entrained by light/dark cycles, most of the flies eclose around lights on. This rhythmic eclosion pattern is controlled by the circadian clock and persists even under constant conditions.
Developmental timing is under the control of complex hormonal signaling, including the steroid ecdysone, insulin-like peptides, and prothoracicotropic hormone (PTTH). The interactions of the central circadian clock in the brain and a peripheral clock in the prothoracic gland (PG) that produces ecdysone are important for the circadian timing of eclosion. These two clocks are connected by a bilateral pair of peptidergic PTTH neurons (PTTHn) that project to the PG. Before each molt, the ecdysone level rises and then falls shortly before ecdysis. The falling ecdysone level must fall below a certain threshold value for the eclosion gate to open. The activity of PTTHn is inhibited by short neuropeptide F (sNPF) from the small ventrolateral neurons (sLNvs) and inhibition is thought to lead to a decrease in ecdysone production.
The general aim of this thesis is to further the understanding of how the circadian clock and neuroendocrinal pathways are coordinated to drive eclosion rhythmicity and to identify when these endocrinal signaling pathways are active. In Chapter I, a series of conditional PTTHn silencing-based behavioral assays, combined with neuronal activity imaging techniques such as non-invasive ARG-Luc show that PTTH signaling is active and required shortly before eclosion and may serve to phase-adjust the activity of the PG at the end of pupal development. Trans-synaptic anatomical stainings identified the sLNvs, dorsal neurons 1 (DN1), dorsal neurons 2 (DN2), and lateral posterior neurons (LPNs) clock neurons as directly upstream of the PTTHn.
Eclosion motor behavior is initiated by Ecdysis triggering hormone (ETH) which activates a pair of ventromedial (Vm) neurons to release eclosion hormone (EH) which positively feeds back to the source of ETH, the endocrine Inka cells. In Chapter II trans-synaptic tracing showed that most clock neurons provide input to the Vm and non-canonical EH neurons. Hence, clock can potentially influence the ETH/EH feedback loop. The activity profile of the Inka cells and Vm neurons before eclosion is described. Vm and Inka cells are active around seven hours before eclosion. Interestingly, all EH neurons appear to be exclusively peptidergic.
In Chapter III, using chemoconnectomics, PTTHns were found to express receptors for sNPF, allatostatin A (AstA), allatostatin C (AstC), and myosuppressin (Ms), while EH neurons expressed only Ms and AstA receptors. Eclosion assays of flies with impaired AstA, AstC, or Ms signaling do not show arrhythmicity under constant conditions. However, optogenetic activation of the AstA neurons strongly suppresses eclosion.
Chapter IV focuses on peripheral ventral’ Tracheal dendrite (v’Td) and class IV dendritic arborization (C4da) neurons. The C4da neurons mediate larval light avoidance through endocrine PTTH signaling. The v’Td neurons mainly receive O2/CO2 input from the trachea and are upstream of Vm neurons but are not required for eclosion rhythmicity. Conditional ablation of the C4da neurons or torso (receptor of PTTH) knock-out in the C4da neurons impaired eclosion rhythmicity. Six to seven hours before eclosion, PTTHn, C4da, and Vm neurons are active based on ARG-Luc imaging. Thus, C4da neurons may indirectly connect the PTTHn to the Vm neurons.
In summary, this thesis advances our knowledge of the temporal activity and role of PTTH signaling during pupal development and rhythmic eclosion. It further provides a comprehensive characterization of the synaptic and peptidergic inputs from clock neurons to PTTHn and EH neurons. AstA, AstC, and Ms are identified as potential modulators of eclosion circuits and suggest an indirect effect of PTTH signaling on EH signaling via the peripheral sensory C4da neurons.
The goal of this thesis was to investigate the influence of rotational restriction between individual parts and of the varying electron density in the bridging unit of D B A systems on the exchange interaction 2J, and thus the electronic coupling between a donor state and an acceptor state. A better understanding of how to influence the underlaying spin dynamics in such donor acceptor systems can open up the door to new technologies, such as modern molecular electronics or optoelectronic devices.
Therefore, three series of molecules consisting of a TAA electron donor, a TTC or ATC bridging unit and a PDI electron acceptor were studied. To investigate the influence of rotational restriction on 2J and the electronic coupling, a series of four rotationally hindered triads (chapter 6) was synthesised. The dihedral angle between the TAA and the TTC as well as between the TTC and the PDI was restricted by ortho methyl groups at the phenylene linkers of the connecting ends to the TTC bridge, producing a twist around the linking single bond which minimises the π overlap. The triads exhibit varying numbers of ortho methyl groups and therefore different degrees of rotational restriction. In order to shine light on the influence of varying electron density on 2J and the electronic coupling, a series of four substituted triptycene triads (chapter 7) was synthesised. The electron density in the TTC bridging unit was varied by electron donating and electron withdrawing groups in 12,13 position of the TTC bridging unit and thus varying its HOMO/LUMO energy. The last series of two anthracene bridge triads (chapter 8) connected both approaches by restricting the rotation with ortho methyl groups and simultaneously by varying the bridge energies.
In order to obtain the electronic properties, steady state absorption and emission spectra of all triads were investigated (chapter 4). Here, all triads show spectral features associated with the separate absorption bands of TAA and the PDI moiety. The reduced QYs, compared to the unsubstituted PDI acceptor, indicate a non radiative quenching mechanism in all triads. The CV data (chapter 5) were used to calculate the energies of possible CSSs and those results were used to assign the CR dynamics into the different Marcus regions. fs TA measurements reveal that all triads form a CSS upon excitation of the PDI moiety. The lifetimes of the involved states and the rate constants were determined by global exponential fits and global target analysis. The CR dynamics upon depopulation of the CSSs were investigated using external magnetic field dependent ns TA spectroscopy. The ns TA maps show that all triads recombine via CRT pathway populating the local 3PDI state in toluene and provided the respective lifetimes. The approximate QYs of triplet formation were determined using actinometry. The magnetic field dependent ns TA data reveal the exchange interaction 2J between singlet and triplet CSS for each triad. Those magnetic field dependent ns TA data in toluene were furthermore treated using a quantum mechanical simulation (done by U.E. Steiner) to extract the rate constants kT and kS for CRT and CRS, respectively. However, the error margins of kS were rather wide. Finally, the electronic couplings between the donor and the acceptor states were obtained by combining the aforementioned experimental results of the rate constants and applying the Bixon Jortner theoretical description of diabatic ET and Andersons perturbative theory of the exchange coupling. Therefore, the experimentally determined values of 2J and the calculated values of kCS and kT were used. The rate constant kS was calculated based on the electronic coupling V1CSS 1S0.
The rotationally hindered triads (chapter 6) show a strong influence of the degree of rotational restriction on the lifetimes and rate constants of the CS processes. The rate constants of CS are increasing with increasing rotational freedom. The magnetic field dependent decay data show that the exchange interactions increase with increasing rotational freedom. Based on the CR dynamics, the calculated electronic couplings of the ET processes reflect the same trend along the series. Here, only singlet couplings turned out to be strongly influenced while the triplet couplings are not. Therefore, this series shows that the ET dynamics of donor acceptor systems can strongly be influenced by restricting the rotational freedom.
In the substituted triptycene triads (chapter 7), decreasing electron density in the bridging unit causes a decrease of the CS rate constants. The magnetic field dependent decay data show that with decreasing electron density in the bridge the exchange interaction decreases. The CR dynamics-based rate constants and the electronic couplings follow the same trend as the exchange interaction. This series shows that varying the HOMO/LUMO levels of the connecting bridge between donor and acceptor strongly influences the ET processes.
In the anthracene bridge triads (chapter 8), the CS process is slow in both triads. The CR was fast in the anthracene triad and is slowed down in the methoxy substituted anthracene bridge triad. The increase of the exchange interaction with increasing electron density in the bridge was more pronounced than in the substituted triptycene triads. Thus, the variation of electron density in the bridge strongly influences the ET processes even though the rotation is restricted.
In this thesis, it was shown that the influence of the rotational hindrance as well as the electron density in a connecting bridge have strong influence on all ET processes and the electronic coupling in donor acceptor systems. These approaches can therefore be used to modify magnetic properties of new materials.
Helically Twisted Graphene Nanoribbons: Bottom-up Stereospecific Synthesis and Characterization
(2024)
Over the past decade, substantial progress has been made in synthesizing atomically precise carbon nanostructures, with a focus on graphene nanoribbons (NRs) through advanced synthetic techniques. Despite these advancements, precise control over the stereochemistry of twisted NRs remains challenging. This thesis introduces a strategic approach to achieve absolute control over the single-handed helical conformation in a cove-edged NR, utilizing enantiopure [n]helicenes as a molecular wrench to intricately dictate the overall conformation of the NR.
Enantiopure [7]helicenes were stitched to the terminal K-regions of a conjugated pyrene NR using a stereospecific and site-selective palladium(II)-catalyzed annulative π-extension (APEX) reaction, resulting in a helically twisted NR with an end-to-end twist of 171°, the second-largest twist reported so far in the literature for twistacenes. The helical end-to-end twist increases with each addition of benzene ring to the central acene core, suggesting that the extra strain induced by the terminal [7]helicenes maintains such a high level of twist.
The quantum chemical calculations were conducted to investigate the impact of twisting on the conformational population. At room temperature, the central backbone of the nanoribbon adopts the twisted helicity opposite to that of the attached [7]helicene, constituting around 99% of the molecular population. For instance, (P)-[7]helicenes produce a left-handed helical nanoribbon, while (M)-[7]helicenes produce a right-handed helical nanoribbon. In the presence of helicenes of opposite chirality, the nanoribbon adopts a waggling conformation. The helically twisted nanoribbons are conformationally robust, as variable temperature chiroptical measurements showed no change in CD and CPL spectra. The proposed strategy, involving the late-stage addition of [n]helicene units through the APEX reaction, appears promising for streamlining the synthesis of diverse cove edge NR variants with desired conformations.
In addition to single-handed helically twisted nanoribbons, the symmetry-based functional properties of C2 and C1 symmetric pyrene-fused single and double [n]helicene compounds were studied. Owing to its higher structural rigidity, the C1 symmetric heptagonal ring-containing molecules exhibited exceptional configurational stability along with remarkable chiroptical properties compared to their C2 symmetric as well as pristine helicene congeners.
Maladaptive avoidance behaviors can contribute to the maintenance of fear, anxiety, and anxiety disorders. It has been proposed that, throughout anxiety disorder progression, extensively repeated avoidance may become a habit (i.e., habitual avoidance) instead of being controlled by internal threat-related goals (i.e., goal-directed avoidance). However, the process of the acquisition of habitual avoidance in anxiety disorders is not yet well understood. Accordingly, the current thesis aimed to investigate experimentally whether trait anxiety and anxiety disorders are associated with an increased shift from goal-directed to habitual avoidance.
The aim of Study 1 was to develop an experimental operationalization of maladaptive habitual avoidance. To this end, we adapted a commonly used action control task, the outcome devaluation paradigm. In this task, habitual avoidance was operationalized as persistent responses after extensive training to avoid an unpleasant stimulus when the aversive outcome was devalued, i.e., when individuals knew the aversive outcome could not occur anymore. We included indicators for costly and low-cost habitual avoidance, whereby habitual avoidance was associated with a monetary cost, while low-cost habitual avoidance was not associated with monetary costs. In Experiment 1 of Study 1, a pronounced costly and non-costly outcome devaluation effect was observed. However, this result may have partly resulted from trial-and-error learning or a better-safe-than-sorry strategy since not instructions about the stimulus-response-outcome contingencies after the outcome devaluation procedure had been provided to the participants. In Experiment 2 of Study 1, instructions on these stimulus-response-outcome contingencies were included to prevent the potential confounders. As a result, we observed no indicators for costly habitual avoidance, but evidence for low-cost habitual avoidance, potentially because competing goal-directed responses could easily be implemented and inhibited costly habitual avoidance tendencies.
In Study 2, the strength of habitual avoidance acquisition was compared between participants with and without anxiety disorders, using the experimental task of Experiment 1 in Study 1. The results indicated that costly and low-cost habitual avoidance was not more pronounced in participants with anxiety disorders than in the healthy control group. However, in an exploratory subgroup comparison, panic disorder predicted more substantial habitual avoidance acquisition than social anxiety disorder.
In Study 3, we investigated whether trait anxiety as a risk factor for anxiety disorders is associated with a specific increased shift from goal-directed to habitual avoidance and approach. The task from the Experiment 1 of Study 1 was adapted to include parallel versions for operationalizing habitual avoidance and habitual approach responses. Using a within-subjects design, the individuals – pre-screened for high and low trait anxiety – took part in the approach and the avoidance outcome devaluation task version. The results suggested stronger non-costly habitual responses in more highly trait-anxious individuals independent of the task version, and suggested a tendency towards an impact of trait anxiety on costly habitual approach rather than on costly habitual avoidance.
In summary, individuals with high trait anxiety or anxiety disorders did not develop habitual avoidance more readily than individuals with low trait anxiety or without anxiety disorders. Therefore, this thesis does not support the assumption that an increased tendency to acquire habitual avoidance contributes to persistent maladaptive avoidance in anxiety disorders. The thesis also contributes to the discourse on the validity of outcome devaluation studies in general by highlighting the impact of task features, such as the instructions after the outcome devaluation procedure or the task difficulty in the test phase, on the experimental results. Such validity issues may partly explain the heterogeneity of findings in research with the outcome devaluation paradigm. We suggest ways towards more valid operationalizations of habitual avoidance in future studies.
In this thesis, a model system of a magnetic topological heterostructure is studied, namely a heterosystem consisting of a single ferromagnetic septuple-layer (SL) of \(MnBi_2Te_4\) on the surface of the three-dimensional topological insulator \(Bi_2Te_3\).
Using MBE and developing a specialized experimental setup, the first part of this thesis deals with the growth of \(Bi_2Te_3\) and thin films of \(MnBi_2Te_4\) on \(BaF_2\)-substrates by the co-evaporation of its binary constituents. The structural analysis is conducted along several suitable probes such as X-ray diffraction (XRD, XRR), AFM and scanning tunnelling electron microscopy (STEM). It is furthermore found that the growth of a single septuple-layer of \(MnBi_2Te_4\) on the surface of \(Bi_2Te_3\) can be facilitated.
By using X-ray absorption and circular magnetic dichroism (XAS, XMCD), the magnetic properties of \(MnBi_2Te_4\) are explored down to the monolayer limit. The layered nature of the vdW crystal and a strong uniaxial magnetocrystalline anisotropy establish stable out-of plane magnetic order at the surface of \(MnBi_2Te_4\), which is stable even down to the 2D limit. Pushing the material system to there, i.e. a single SL \(MnBi_2Te_4\) further allows to study the phase transition of this 2D ferromagnet and extract its critical behaviour with \(T_c \, = \, 14.89~k\) and \(\beta \, = \, 0.484\).
Utilizing bulk crystals of the ferromagnetic \(Fe_3GeTe_2\) as substrate allows to influence, enhance and bias the magnetism in the single SL of \(MnBi_2Te_4\). By growing heterostructures of the type \(MnBi_2Te_4\) -- n layer \(Bi_2Te_3\) -- \(Fe_3GeTe_2\)for n between 0 and 2, it is shown, that a considerable magnetic coupling can be introduced between the \(MnBi_2Te_4\) top-layer and the substrate.
Finally the interplay between topology and magnetism in the ferromagnetic extension is studied directly by angle-resolved photoemission spectroscopy. The heterostructure is found to host a linearly dispersing TSS at the centre of the Brillouin zone. Using low temperature and high-resolution ARPES a large magnetic gap opening of \(\sim\) 35 meV is found at the Dirac point of the TSS. By following its temperature evolution, it is apparent that the scaling behaviour coincides with the magnetic order parameter of the modified surface.
Das maligne Melanom, eine der seltensten, aber gleichzeitig auch die tödlichste dermatologische Malignität, gekennzeichnet durch die Neigung zu einer frühen Metastasierung sowie die rasche Entwicklung von Therapieresistenzen, zählt zu den Tumorentitäten mit dem höchsten Anstieg der Inzidenz weltweit. Mausmodelle werden häufig verwendet, um die Melanomagenese zu erforschen und neue effektive therapeutische Strategien zu entwickeln, spiegeln die menschliche Physiologie allerdings nur unzureichend wider. In zweidimensionalen (2D) Zellkulturen mangelt es dagegen an wichtigen Komponenten der Mikroumgebung des Tumors und dem dreidimensionalen Gewebekontext. Um dieses Manko zu beheben und die Entwicklung von auf den Menschen übertragbaren Tumormodellen in der onkologischen Forschung voranzutreiben, wurde als Alternative zu Zellkulturen und Tierversuchen humane organotypische dreidimensionale (3D) Melanom-Modelle als in vitro Testsystem für die Bewertung der Wirksamkeit von anti-Tumor Therapeutika entwickelt.
Im Zuge dieser Arbeit konnte das in vitro Melanom-Modell entscheidend weiterentwickelt werden. So konnten Modelle unterschiedlichster Komplexität etabliert werden, wobei abhängig von der Fragestellung einfachere epidermale bis hin zu unterschiedlich komplexen Vollhautmodellen Anwendung finden. Durch Simulation der Tumor-Mikroumgebung eignen sich diese zur präklinischen Validierung neuer Tumor-Therapeutika, sowie der Erforschung pathologischer Vorgänge, von der Tumor-Formierung bis zur Metastasierung. Zudem konnten erfolgreich unterschiedlichste humane Melanomzelllinien ins Modell integriert werden; dadurch, dass sich diese durch ihre Treibermutationen, die zur Krankheitsentstehung beitragen, unterscheiden, stellen sie unterschiedliche Ansprüche an potentielle therapeutische Angriffspunkte und ermöglichen das Widerspiegeln vieler Melanom-Subtypen im Modell. Ferner ist es möglich, verschiedene Stadien der Tumor-Entwicklung über die Zugabe von Melanomzellen in Einzelsuspension bzw. von Melanom-Sphäroiden widerzuspiegeln. Es konnte für bestimmte Therapie-Ansätze, wie zielgerichtete Therapien, z.B. die Gabe von sich in der Klinik im Einsatz befindlicher BRAF-/MEK-Inhibitoren, gezeigt werden, dass sich die etablierten Modelle hervorragend als präklinische Testsysteme zur Wirksamkeitsbewertung eignen. Zudem bieten sich einzigartige Möglichkeiten, um die Interaktion humaner Tumorzellen und gesunder Zellen in einem Gewebeverband zu untersuchen. Ferner konnten drei neue technische Analyse-Verfahren zur nicht-invasiven Detektion der Tumor- Pro- und Regression, Beurteilung der Wirksamkeit von potenziellen Anti-Tumor-Therapien sowie der Evaluierung des Tumor-Metabolismusses implementiert werden. Perspektivisch ermöglichen immun-kompetente Melanom-Modelle die Austestung neuer Immun- und Zelltherapien in einem voll humanen System; gleichzeitig leisten die etablierten Modelle einen signifikanten Beitrag zur Reduktion von Tierexperimenten.
Politische Bildung übt nicht nur einen großen Einfluss auf die zukünftige Konstellation des politischen Systems aus, sondern beeinflusst ebenfalls das soziale Miteinander prägend. Damit werden entscheidende Weichen für die Entwicklung der Gesellschaft, der Nation und des Staates gestellt. Im Zuge dieses Prozesses durchläuft jeder junge Bürger einen politischen Bildungsweg an Schulen. Die Vorgaben darüber, wie schulische politische Bildung auszusehen hat und welche Kompetenzen Schüler in diesem Zusammenhang erwerben sollen, geben die Kultus- bzw. Bildungsministerien in Curricula vor, verbindlich für alle Lehrer. Durch eine komparative Analyse der Curricula kann damit eindeutig die staatlich vorgegebene politische, gesellschaftliche und soziale Richtung festgestellt werden, die junge Menschen einschlagen sollen. Welche edukativen Ziele der politischen Bildung werden verfolgt? Was sollen Schüler lernen, um mit diesen Kompetenzen die Zukunft ihres Kollektivs zu gestalten? Wo liegen die Gemeinsamkeiten und Unterschiede zweier Staaten, in unserem Fall Deutschlands und Polens, im Hinblick auf die schulische politische Bildung? Beantwortet werden diese Fragestellungen durch das Anwenden zweier Methoden der qualitativen Sozialforschung, der komparativen Inhaltsanalyse, zum einen der strukturierenden zum anderen der induktiven. Davor erfolgt eine komparativ quantitative Untersuchung, die den Umfang der Unterrichtszeit in den Leitfächern für politische Bildung in allen Bundesländern und in Polen vergleicht, was einer empirischen Totalerhebung der komplex umfangreichen Daten entspricht. Die quantitativen Forschungsergebnisse zeigen deutliche Differenzen zwischen Deutschland und Polen, in einem der beiden Staaten wird signifikant mehr Zeit für politische Bildung im Leitfach dieser Disziplin investiert als im anderen. Anhand der qualitativen Daten ist zu erkennen, dass einerseits eine gemeinsame Grundbasis von Kompetenzen der politischen Bildung zwischen Deutschland und Polen besteht. Anderseits stechen in beiden Ländern eindeutige Unterschiede hervor, deren Ursprung zum einen historische Erfahrungen der Nationen und Staaten abbildet, zum anderen aktuell gegensätzliche politische Interessen untermauert.
Im Zentrum der Arbeit stehen als zwei Werke der hochmittelalterlichen Moraldidaxe: der ‚Welsche Gast‘ sowie die in zeitlicher Nähe entstandenen ‚Winsbeckischen Gedichte‘. Bei aller formalen Unterschiedlichkeit der Texte werden sie dadurch geeint, dass sie sowohl männliches als auch weibliches Verhalten thematisieren, wobei der ‚Welsche Gast‘ in seiner Herren- und Fürstenlehre auch ein älteres Publikum anspricht, während sich die Hofzucht des ‚Welschen Gasts‘ sowie ‚Winsbecke‘ und ‚Winsbeckin‘ auf heranwachsende Adlige beschränken.
Ziel ist es, die Konstruktion von Geschlecht aufzudecken, wobei Analysemethoden der modernen sozialphilosophischen Forschung zum Einsatz kommen. Michel Foucault bietet mit seiner Diskursanalyse ein probates Mittel, gesellschaftliche Zustände und die Konstruktion von Identitäten aufzudecken. Die amerikanische Philosophin Judith Butler greift bei ihren Überlegungen zur Konstruktion von Geschlecht unter anderem auf Foucault zurück und zeigt auf, welche Mechanismen bei der Gestaltung geschlechtlicher Identitäten wirksam werden.
Die Verknüpfung moderner Theorie mit mittelalterlicher Moraldidaxe erweist sich insofern als fruchtbar und sinnvoll, als gerade mittelalterliche (und – diskursiv tradiert – auch ältere) Vorstellungen von Geschlecht bzw. rollenadäquatem Verhalten ihren Niederschlag noch in moderner Ratgeberliteratur (z. B. Mädchenerziehungsschriften der 1950er Jahre) finden.
So kann als Mittel der Analyse auf die von Judith Butler inspirierte Gendertheorie zurückgegriffen werden kann, ohne die Gegebenheiten der mittelalterlichen Literatur und die Restriktionen der Gattung zu vernachlässigen.
Zu diesem Zweck werden in der Arbeit – anders als bislang üblich – die Gesamttexte (und nicht nur besonders auffällige ‚Stellen‘ der Didaxen) hinsichtlich der in ihnen enthaltenen Bilder von Weiblichkeit bzw. Männlichkeit formal und inhaltlich untersucht. Beim ‚Welschen Gast werden zudem die zahlreichen Visualisierungen in die Einzelanalysen und bei den
‚Winsbeckischen Gedichten‘ nicht nur der an Männer und der an Frauen gerichtete Teil, sondern auch die Parodie des Winsbecken miteinbezogen.
Nach einer ausführlichen Klärung der theoretischen und literaturwissenschaftlichen Voraussetzungen (Gender und Genderforschung, Performativität und Performanz, lehrhafte Dichtung im Mittelalter) wird das Korpus nach den Gesichtspunkten
• Redeverhalten
• Körperverhalten
• Emotionales Verhalten, Tugenden und Laster
untersucht und die Ergebnisse in einem Schlußkapitel zusammengefasst.
Die Studie knüpft an das Interesse der feministischen Literaturwissenschaft an, berücksichtigt aber das geschlechterübergreifende Genderkonzept und würdigt im Sinne eines close reading explizit den literarischen Charakter der Texte (strukturelle Performativität) sowie den symbolischen der Abbildungen. Im Ergebnis können Spielräume der grundsätzlich an patriarchaler Hierarchie und ständischer Stabilität orientierten Gattung im Hinblick auf die Genderfrage ausgemacht werden, die Ausbrüche aus den vorgegebenen und damit intelligiblen Rahmungen ermöglichen (z.B. bei den verwendeten Metaphern), aber auch ‚Rückschritte’ demonstrierten (z.B. bei der in einzelnen Illustrationen erkennbaren, im begleitenden Text aber nicht nachweisbaren Misogynie).
Dennoch wird ein männlicher Blick auf eine Welt deutlich, in der die Frau meist als schmückendes Beiwerk fungiert, deren Handlungsmacht sich auf das ‚Häusliche‘ beschränkt. Raumanmaßung steht nur Männern offen, wobei der Radius der Handelnden von Alter und Stand beschränkt wird.
Die mit dem Klimawandel einhergehenden Umweltveränderungen, wie steigende Temperaturen, Abnahme der Sommer- und Zunahme der Winterniederschläge, häufigere und längere Trockenperioden, zunehmende Starkniederschläge, Stürme und Hitzewellen betreffen besonders den Bodenwasserhaushalt in seiner zentralen Regelungsfunktion für den Landschaftswasserhaushalt. Von der Wasserverfügbarkeit im Boden hängen zu einem sehr hohen Grad auch die Erträge der Land- und Forstwirtschaft ab. Eine besonders große Bedeutung kommt dabei der Wasserspeicherkapazität der Böden zu, da während einer Trockenphase die effektiven Niederschläge den Wasserbedarf der Pflanzen nicht decken können und das bereits gespeicherte Bodenwasser das Überleben der Pflanzen sicherstellen kann. Für die land- und forstwirtschaftlichen Akteure sind in diesem Kontext quantitative und qualitative Aussagen zu den Auswirkungen des Klimawandels auf den Boden essenziell, um die notwendigen Anpassungsmaßnahmen für ihre Betriebe treffen zu können.
Zielsetzungen der vorliegenden Arbeit bestehen darin, die Dynamik der Bodenfeuchte in unterfränkischen Böden besser zu verstehen, die Datenlage zum Verlauf der Bodenfeuchte zu verbessern und die Auswirkungen von prognostizierten klimatischen Parametern abschätzen zu können. Hierzu wurden an sechs für ihre jeweiligen Naturräume und hinsichtlich ihrer anthropogenen Nutzung charakteristischen Standorten meteorologisch-bodenhydrologische Messstationen installiert. Die Messstationen befinden sich in einem Rigosol auf Buntsandstein in einem Weinberg bei Bürgstadt sowie auf einer Parabraunerde im Lössgebiet bei Herchsheim unter Ackernutzung. Am Übergang von Muschelkalk in Keuper befinden sich die Stationen in Obbach, wo eine Braunerde unter Ackernutzung vorliegt und im Forst des Universitätswalds Sailershausen werden die Untersuchungen in einer Braunerde-Terra fusca durchgeführt. Im Forst befinden sich auch die Stationen in Oberrimbach mit Braunerden aus Sandsteinkeuper und in Willmars mit Braunerden aus Buntsandstein. Der Beobachtungszeitraum dieser Arbeit reicht von Juli 2018 bis November 2022. In diesen Zeitraum fiel die dreijährige Dürre von 2018 bis 2020, das Jahr 2021 mit einem durchschnittlichen Witterungsverlauf und das Dürrejahr 2022.
Das Langzeitmonitoring wurde von umfangreichen Gelände- und Laboranalysen der grundlegenden bodenkundlichen Parameter der Bodenprofile und der Standorte begleitet. Die bodengeographischen-geomorphologischen Standortanalysen bilden zusammen mit den qualitativen Auswertungen der Bodenfeuchtezeitreihen die Grundlage für Einschätzungen zu den Auswirkungen des Klimawandels auf den Bodenwasserhaushalt. Verlässliche Aussagen zum Bodenwasserhaushalt können nur auf Grundlage von zeitlich und räumlich hoch aufgelösten Daten getroffen werden. Bodenfeuchtezeitreihen zusammen mit den bodenphysikalischen Daten lagen in dieser Datenqualität für Unterfranken bisher nur sehr vereinzelt vor.
Die vorliegenden Ergebnisse zeigen, dass die untersuchten Böden entsprechend den jeweiligen naturräumlichen Gegebenheiten sehr unterschiedliche bodenhydrologische Eigenschaften aufweisen. Während langer Trockenphasen können beispielsweise die Parabraunerden am Standort Herchsheim wegen ihrer höheren Wasserspeicherkapazität die Pflanzen länger mit Wasser versorgen als die sandigen Braunerden am Standort Oberrimbach. Die Bodenfeuchteregime im Beobachtungszeitraum waren sehr stark vom Witterungsverlauf einzelner Jahre abhängig. Das Bodenfeuchteregime bei einem durchschnittlichen Witterungsverlauf wie in 2021 zeichnet sich durch eine langsame Abnahme der Bodenfeuchte ab Beginn der Vegetationsperiode im Frühjahr aus. Regelmäßige Niederschläge im Frühjahr füllen den oberflächennahen Bodenwasserspeicher immer wieder auf und sichern den Bodenwasservorrat in der Tiefe bis in den Hochsommer. Im Hochsommer können Pflanzen dann während der Trockenphasen ihren Wasserbedarf aus den tieferen Horizonten decken. Im Gegensatz dazu nimmt die Bodenfeuchte in Dürrejahren wie 2018 bis 2020 oder 2022 bereits im Frühjahr bis in die untersten Horizonte stark ab. Die nutzbare Feldkapazität ist zum Teil schon im Juni weitgehend ausgeschöpft, womit für spätere Trockenphasen kein Bodenwasser mehr zur Verfügung steht. Die Herbst- und Winterniederschläge sättigen den Bodenwasservorrat wieder bis zur Feldkapazität auf. Bei tiefreichender Erschöpfung des Bodenwassers wurde die Feldkapazität erst im Januar oder Februar erreicht.
Im Zuge der land- und forstwirtschaftlichen Nutzung ist eine gute Datenlage zu den bodenkundlichen und standörtlichen Gegebenheiten für klimaadaptierte Anpassungsstrategien essentiell. Wichtige Zielsetzungen bestehen grundsätzlich in der Erhaltung der Bodenfunktionen, in der Verbesserung der Infiltrationskapazität und Wasserspeicherkapazität. Hier kommt dem Boden als interaktive Austauschfläche zwischen den Sphären und damit dem Bodenschutz eine zentrale Bedeutung zu. Die in Zukunft erwarteten klimatischen Bedingungen stellen an jeden Boden andere Herausforderungen, welchen mit standörtlich abgestimmten Bodenschutzmaßnahmen begegnet werden kann.
Als quantitative Textanalysemethode ist das LDA Topic Modeling in den letzten Jahren in den Digital Humanities weit verbreitet worden, um zahlreiche unstrukturierte Textdaten zu untersuchen. Wenn man LDA Topic Modeling anwendet, muss man mit vielen Faktoren umgehen, die das Ergebnis der Modellierung beeinflussen können. In dieser Dissertation wurde das LDA Topic Modeling, genauer gesagt sechs entscheidende Faktoren, durch Experimente evaluiert, nämlich die Anzahl der Topics, der Hyperparameter Alpha, die Hyperparameter-Optimierung, der Hyperparameter Beta, die Iteration des Gibbs-Samplings und das Chunk-Length. Der Einfluss der sechs Faktoren wurde anhand eines deutschen Zeitungskorpus und eines deutschen Romankorpus aus zwei Perspektiven, der Dokumentklassifikation und der Topic-Kohärenz, untersucht. Ziel ist es, die Frage zu beantworten, unter welchen Umständen das LDA Topic Modeling stabil ist und damit einen Einblick in die Sensitivität der Methode gegenüber Parametereinstellungen zu geben.
Einleitung:
Die Ätiologie der Early Onset Arthrose (EOA) der Schulter ist bislang ungeklärt. Aufgrund des Einflusses der Muskeln der Rotatorenmanschette (RM) auf die glenohumerale Kinematik werden muskuläre Ursachen diskutiert. Ziel der Studie war es, entsprechende Faktoren anhand von Volumenmessungen der RM und Untersuchungen der angrenzenden knöchernen Strukturen in der MRT-Bildgebung sowie der Erfassung patientenspezifischer Charakteristika zu identifizieren.
Methoden:
In einer Fall-Kontroll-Studie wurden Schultern von 15 PatientInnen (14 Männer, 1 Frau) mit einer Omarthrose vor dem 60. Lebensjahr und 13 Kontrollpersonen (ausschließlich Männer) untersucht. Dabei wurden anthropometrische Körpermessungen sowie klinische Charakteristika erhoben. Anhand von MRT-Bildern wurden die Volumina der RM mittels manueller Umrandung der einzelnen Muskelquerschnitte berechnet. Weiterhin wurden die Winkel zwischen Coracoid bzw. Spina scapulae und Scapulakörper gemessen. Die Stellung der Scapula zum Thorax wurde anhand des Winkels der Scapula zur Tischebene erhoben. Zudem wurden die Glenoidretroversion, -morphologietypen und Humeruskopfsubluxation ermittelt. Die Auswertung erfolgte anhand deskriptiver und vergleichender statistischer Verfahren sowie logistischer und linearer Regressionsanalysen.
Ergebnisse:
Die Volumina der RM von PatientInnen mit EOA unterschieden sich weder absolut noch im relativen Verhältnis von denen der Kontrollpersonen. Dagegen konnten im Vergleich signifikant höhere Werte des Thoraxumfangs und -durchmessers, des Körpergewichts sowie des BMI bei erkrankten Personen nachgewiesen werden. Weiterhin übten diese signifikant häufiger Berufe aus, die mehr als 1400 kcal pro Tag verbrauchten. Das Risiko einer EOA nahm zu, je steiler die Scapula zum Thorax stand. PatientInnen mit B2-Glenoid wiesen signifikant größere Winkel zwischen Coracoid und Scapulakörper sowie höhere Werte des transversalen Thoraxdurchmessers auf, als erkrankte Personen mit einem B1-Glenoid. Unabhängig von einer Erkrankung mit EOA zeigte sich, dass das Ausüben einer Überkopfsportart mit einem höheren Subluxationsindex assoziiert war.
Fazit:
Während die RM keine Auffälligkeiten bei PatientInnen mit EOA zeigte, waren ein männliches Geschlecht, der BMI, die Thoraxform und Scapulastellung, sowie die Ausübung bestimmter Berufe und Sportarten mit der Erkrankung assoziiert. Weitere Studien müssen folgen, um diese Risikofaktoren bei EOA genauer zu untersuchen und mögliche Therapiekonzepte zu entwickeln. Dabei sollte auch die periphere Schultermuskulatur (z. B. M. teres major oder M. pectoralis major) in die Untersuchungen miteinbezogen werden.
Hintergrund: Bei der Entscheidung für eine intravenöse Kortikosteroid-Pulstherapie bei schweren Formen der AA ist die Abwägung von Therapieaufwand, Nebenwirkungen und Risiken einerseits und der Erfolgsaussicht andererseits von zentraler Bedeutung.
Ziel: Ziel dieser retrospektiven Analyse war es daher, die Wirksamkeit und Sicherheit der intravenösen Kortikosteroid-Pulstherapie bei Patient:innen mit ausgeprägter AA klinikintern als qualitätssichernde Maßnahme zu untersuchen, prognostisch bedeutsame Faktoren für den Therapieeffekt zu ermitteln und hierdurch die beste Indikation herauszuarbeiten.
Methode: 126 Patient:innen (13 Kinder und Jugendliche) erhielten Dexamethason 100 mg (122 Patienten) oder Methylprednisolon 20-30 mg/kg/KG (max. 1000 mg, 4 Patienten) an drei aufeinanderfolgenden Tagen für ein bis drei Zyklen.
Ergebnisse: Patienten mit einer AA partialis bzw. diffusa zeigten im Hinblick auf ein vollständiges oder kosmetisch akzeptables Wiederwachstum die besten Ansprechraten (44,3%, n=43). Unter den Ophiasis-Patienten und den Patienten mit AA totalis/universalis sprach nur etwa ein Viertel auf die Therapie an (Ophiasis 23,8%, n=5; AA totalis/universalis: 25%, n=2). Schwerwiegende unerwünschte Nebenwirkungen wurden nicht beobachtet.
Schlussfolgerung: In der vorliegenden Untersuchung ließen sich eine längere Bestandsdauer der Erkrankung und Erkrankungsepisode (über 6 Monate), ein schwerer Ausprägungsgrad (Ophiasis, AA totalis/universalis) und krankheitstypische Nagelveränderungen als wichtige ungünstige prognostische Faktoren nachweisen. Dagegen wirkten sich die untersuchten Kriterien Alter, Geschlecht, atopisches Ekzem und andere Erkrankungen des atopischen Formenkreises, Schilddrüsen- und Autoimmunerkrankungen in der Eigenanamnese sowie AA in der Familienanamnese nicht negativ auf den Behandlungserfolg aus. Patienten mit AA partialis und einer Bestandsdauer der AA von maximal 6 Monaten haben die besten Erfolgsaussichten.
Eine gefürchtete Komplikation nach Resektionen am Kolon mit Wiederherstellung der Kontinuität ist das Auftreten einer Anastomoseninsuffizienz (AI). Der Prozess der Diagnosestellung und das therapeutische Vorgehen sind zentrumsspezifisch und sehr heterogen. Ziel dieser Promotionsarbeit war die deskriptive Darstellung der Prävalenz, Diagnostik und Therapie von AI, um anhand dieser Daten ein bestimmtes zu favorisierendes Vorgehen zur AI-Behandlung herauszuarbeiten.
Es wurde eine retrospektive unizentrische Analyse durchgeführt. Diese umfasste eine Kohorte von 744 Patienten, welche von 2009 bis 2013 am Universitätsklinikum Würzburg unter Kontinuitätserhalt kolorektal reseziert wurden. Es erfolgte eine deskriptive und statistische Auswertung mittels uni- und multivariater Analysen in Bezug auf Demographie, Risikofaktoren für die Entwicklung einer AI und den Erfolg der einzelnen Therapiekonzepte.
Während der Nachbeobachtungsphase vom im Mittel 2,5 Jahren entwickelten 10,48% der Patienten eine AI. 60% der Insuffizienzen wurden während der ersten 7 postoperativen Tage detektiert. Als Risikofaktoren konnten indikationsunabhängig männliches Geschlecht, offener Zugangsweg und pulmonale Erkrankungen herausgearbeitet werden. Indikationsspezifisch zeigte sich eine Zunahme des AI-Risikos bei Divertikulitis-Patienten mit pulmonalen Erkrankungen (OR 4,5) und Cortisoneinnahme (OR 5,4). Auffällig wurden Patienten mit AI durch heterogene und teils unspezifische Symptome – am häufigsten durch Fieber (28,21%) und auffällige Laborwerte (48,72%). Eine folgende CT-Diagnostik bestätigte die Diagnose in 76,32% der Fälle und war in 24,48% falsch negativ. Patienten mit schlechtem AZ bei Diagnose der AI zeigten eine signifikant höhere Mortalität. Ein protektives Stoma konnte eine AI nicht verhindern, aber ihre Symptome und die Schwere des Verlaufs abmildern. Gemessen an der Überlebensrate und der Revisionspflichtigkeit unterschieden sich die durchgeführten Maßnahmen beim Versuch der kontinuitätserhaltenden Therapie nicht in Bezug auf den Erfolg der Therapie.
Wie Insuffizienz- und Mortalitätsrate nach AI zeigen, ist diese unizentrische Analyse international vergleichbar. Die Ableitung einer generellen Empfehlung zur therapeutischen Vorgehensweise bei AI ist nicht möglich. Vielmehr sind alle dargestellten Maßnahmen zur Beherrschung der AI sinnvoll, während die Wahl der Vorgehensweise weiterhin eine Individualentscheidung bleibt.
Ziel dieser Studie war es, zu eruieren, ob die DSE zur Unterscheidung einer TS- von einer PSAS beitragen kann. Ebenfalls untersuchten wir, ob es bestimmte echokardiographische Prädiktoren für eine TS- und eine PSAS gibt und ob die LVEF bei Patienten mit einer LGAS eine entscheidende Rolle spielt. Methoden: Es wurde bei 130 Patienten mit einer asymptomatischen AS im Uniklinikum Würzburg zwischen Januar 2011 und Dezember 2016 sowohl eine TTE als auch eine DSE durchgeführt. Mittels TTE wurden verschiedene echokardiographische Daten erhoben und falls die Patienten eine AVAi 0,6 cm2/m2 und eine PGmean < 40 mmHg aufwiesen, wurden sie in die Studie eingeschlossen. Sie wurden in zwei Gruppen aufgeteilt, je nachdem ob sie eine LGAS mit einer LVEF 50% oder < 50% aufwiesen. Bei allen Patienten wurde in der DSE die AVAproj berechnet und sie wurden daraufhin in zwei Untergruppen aufgeteilt, Patienten mit einer AVAproj 1 cm2 wurden der Gruppe mit einer hochgradigen LGAS (TS-LGAS) und Patienten mit einer AVAproj > 1cm2 der Gruppe mit einer pseudo-hochgradigen LGAS (PS-LGAS) zugeteilt. Alle Patientendaten wurden manuell ausgewertet. Das klinische Follow Up fand frühestens ein Jahr nach der DSE statt und bestand aus einem Telefoninterview oder einer klinischen Untersuchung. Ergebnisse: Die DSE ist zur Diagnose einer TS-LGAS bei Patienten mit einer erhaltenen LVEF von großem Nutzen. Die in der TTE gemessene AVA ist ein unabhängiger Prädiktor für eine TS-LGAS bei Patienten mit erhaltener und reduzierter LVEF. Eine verringerte MAPSE und eine reduzierte TDI-s´ sprechen bei Patienten mit erhaltener LVEF für eine TS-LGAS. Bei Patienten mit reduzierter LVEF weisen ein erhöhter sPAP und eine verringerte AV Geschwindigkeits Ratio auf eine TS-LGAS hin. Bei Zweifeln können weitere bildgebende Verfahren zur Diagnosefindung hinzugezogen werden.
Das Vestibularisschwannom ist ein Tumor, dessen Entstehung noch nicht vollständig geklärt ist. Jeder kann von dieser seltenen Erkrankung betroffen sein. Darum ist es wichtig, die Ergebnisse der verschiedenen Therapieoptionen regelmäßig aufzuarbeiten und die Möglichkeiten einer Hörrehabilitation mit konventionellen oder implantierbaren Hörsystemen sowie Ansätze zur Schwindelrehabilitation oder einer möglichen Prähabilitation zu evaluieren. Mit der transtemporalen mikrochirurgischen Tumorexstirpation kann eine Heilung und bei einem großen Teil der Patienten auch ein Hörerhalt erzielt werden. Je jünger die Patienten sind, aber vor allem auch je besser sie vor der Operation hören, desto höher sind auch die Chancen auf einen Hörerhalt. Es zeigte sich jedoch auch, dass bei Patienten mit initial schlechterem Hören, welche dann operiert wurden, dieses zum Teil wieder verbessert werden konnte. Daher sind Ansätze, mehr Patienten eine transtemporale Tumorresektion anzubieten durchaus sinnvoll, auch um die Chancen auf eine Hörverbesserung zu ermöglichen. Des Weiteren sollte auch bei Patienten mit Schwindelbeschwerden eine Operation als Behandlungsoption erwogen werden. Die Prähabilitation mit Gentamicin-Injektionen in das Mittelohr scheint eine neue Möglichkeit zu sein, das zentrale Nervensystem schon auf den Ausfall des Vestibularorgans vorzubereiten. Durch die ototoxische Wirkung des Gentamicins und den potenziellen Hörverlust, wäre jedoch eine Kombination dieser Prähabilitation mit einem hörerhaltenden Eingriff über den transtemporalen Zugang risikobehaftet. Eine zentrale Kompensation der Schwindelbeschwerden sollte nach dem Eingriff mit einer gezielten Schwindelrehabilitation unterstützt werden. Während bei dieser vor allem physiotherapeutische Übungen angewandt werden, gibt es im Hinblick auf eine Hörrehabilitation schon verschiedene medizintechnische Optionen. Aktuell gibt es vor allem Studien zu den implantierbaren Hörhilfen und neue Daten zu den konservativen Möglichkeiten einer Hörrehabilitation sind eher die Ausnahme. Die Nutzung einer konservativen Hörhilfe sollte jedoch vor dem Entscheid zu einer operativen Lösung über implantierbare Systeme konsequent angewandt werden. Die in dieser Arbeit aufgezeigten positiven Momente bei der Versorgung von VS-Patienten prä- und posttherapeutisch mit herkömmlichen Hörgeräten sollten weiteren Eingang in die klinische Routine finden.
Learning accompanies us throughout our lives, from early childhood education through
school, training and university to learning at work. However, much of what we learn is quickly
forgotten. The use of practice tests is a learning strategy that contributes to the acquisition of
sustainable knowledge, i.e. knowledge that is permanently available and can be retrieved when
it is needed. This dissertation first presents findings from previous research on testing in real
educational contexts and discusses theoretically why certain learner or situational
characteristics might influence the effectiveness of the testing effect. Furthermore, a cycle of
three experiments is presented, which were used to investigate whether the positive effect of
practice tests on retention (testing effect) depends on personal or situational characteristics and
also promotes the retention of lecture content that was not directly tested (transfer) in the context
of regular psychology lectures in teacher training courses. In an additional chapter, feedback
from students on the implementation of the study in the classroom context is examined in more
detail. Finally, the results of the three studies are discussed and placed in relation to the theories
presented. The central conclusion from the studies presented is that the testing effect appears to
be a very effective learning strategy that can be used effectively in university teaching and leads
to better learning outcomes regardless of learner characteristics. However, the practice tests
should cover the entire range of relevant content, as transfer effects to non-tested content are
not to be expected.
Since the prediction of the quantum spin Hall effect in graphene by Kane and Mele, \(Z_2\) topology in hexagonal monolayers is indissociably linked to high-symmetric honeycomb lattices. This thesis breaks with this paradigm by focusing on topological phases in the fundamental two-dimensional hexagonal crystal, the triangular lattice. In contrast to Kane-Mele-type systems, electrons on the triangular lattice profit from a sizable, since local, spin-orbit coupling (SOC) and feature a non-trivial ground state only in the presence of inversion symmetry breaking. This tends to displace the valence charge form the atomic position. Therefore, all non-trivial phases are real-space obstructed. Inspired by the contemporary conception of topological classification of electronic systems, a comprehensive lattice and band symmetry analysis of insulating phases of a \(p\)-shell on the triangular lattice is presented. This reveals not only the mechanism at the origin of band topology, the competition of SOC and symmetry breaking, but sheds also light on the electric polarization arising from a displacement of the valence charge centers from the nuclei, i. e., real-space obstruction. In particular, the competition of SOC versus horizontal and vertical reflection symmetry breaking gives rise to four topologically distinct insulating phases: two kinds of quantum spin Hall insulators (QSHI), an atomic insulator and a real-space obstructed higher-order topological insulator. The theoretical analysis is complemented with state-of-the-art first principles calculations and experiments on trigonal monolayer adsorbate systems. This comprises the recently discovered triangular QSHI indenene, formed by In atoms, and focuses on its topological classification and real-space obstruction. The analysis reveals Kane-Mele-type valence bands which profit from the atomic SOC of the triangular lattice. The realization of a HOTI is proposed by reducing SOC by considering lighter adsorbates. Further the orbital Rashba effect is analyzed in AgTe, a consequence of mirror symmetry breaking, the formation of local angular momentum polarization and SOC. As an outlook beyond topology, the Fermi surface and electronic susceptibility of Group V adsorbates on silicon carbide are investigated.
In summary, this thesis elucidates the interplay of symmetry breaking and SOC on the triangular lattice, which can promote non-trivial insulating phase.
Adoptive cellular immunotherapy with chimeric antigen receptor (CAR) T cells is highly effective in haematological malignancies. This success, however, has not been achieved in solid tumours so far. In contrast to hematologic malignancies, solid tumours include a hostile tumour microenvironment (TME), that poses additional challenges for curative effects and consistent therapeutic outcome. These challenges manifest in physical and immunological barriers that dampen efficacy of the CAR T cells. Preclinical testing of novel cellular immunotherapies is performed mainly in 2D cell culture and animal experiments. While 2D cell culture is an easy technique for efficacy analysis, animal studies reveal information about toxicity in vivo. However, 2D cell culture cannot fully reflect the complexity observed in vivo, because cells are cultured without anchorage to a matrix and only short-term periods are feasible. Animal studies provide a more complex tissue environment, but xenografts often lack human stroma and tumour inoculation occurs mostly ectopically. This emphasises the need for standardisable and scalable tumour models with incorporated TME-aspects, which enable preclinical testing with enhanced predictive value for the clinical outcome of immunotherapies. Therefore, microphysiologic 3D tumour models based on the biological SISmuc (Small Intestinal mucosa and Submucosa) matrix with preserved basement membrane were engaged and improved in this work to serve as a modular and versatile tumour model for efficacy testing of CAR T cells. In order to reflect a variety of cancer entities, TME-aspects, long-term stability and to enhance the read-out options they were further adapted to achieve scalable and standardisable defined microphysiologic 3D tumour models. In this work, novel culture modalities (semi-static, sandwich-culture) were characterised and established that led to an increased and organised tissue generation and long-term stability. Application of the SISmuc matrix was extended to sarcoma and melanoma models and serial bioluminescence intensity (BLI)-based in vivo imaging analysis was established in the microphysiologic 3D tumour models, which represents a time-efficient read-out method for quality evaluation of the models and treatment efficacy analysis, that is independent of the cell phenotype. Isolation of cancer-associated-fibroblasts (CAFs) from lung (tumour) tissue was demonstrated and CAF-implementation further led to stromal-enriched microphysiologic 3D tumour models with in vivo-comparable tissue-like architecture. Presence of CAFs was confirmed by CAF-associated markers (FAP, α-SMA, MMP-2/-9) and cytokines correlated with CAF phenotype, angiogenesis, invasion and immunomodulation. Additionally, an endothelial cell barrier was implemented for static and dynamic culture in a novel bioreactor set-up, which is of particular interest for the analysis of immune cell diapedesis. Studies in microphysiologic 3D Ewing’s sarcoma models indicated that sarcoma cells could be sensitised for GD2-targeting CAR T cells. After enhancing the scale of assessment of the microphysiologic 3D tumour models and improving them for CAR T cell testing, the tumour models were used to analyse their sensitivity towards differently designed receptor tyrosine kinase-like orphan receptor 1 (ROR1) CAR T cells and to study the effects of the incorporated TME-aspects on the CAR T cell treatment respectively. ROR1 has been described as a suitable target for several malignancies including triple negative breast cancer (TNBC), as well as lung cancer. Therefore, microphysiologic 3D TNBC and lung cancer models were established. Analysis of ROR1 CAR T cells that differed in costimulation, spacer length and targeting domain, revealed, that the microphysiologic 3D tumour models are highly sensitive and can distinguish optimal from sub-optimal CAR design. Here, higher affinity of the targeting domain induced stronger anti-tumour efficacy and anti-tumour function depended on spacer length, respectively. Long-term treatment for 14 days with ROR1 CAR T cells was demonstrated in dynamic microphysiologic 3D lung tumour models, which did not result in complete tumour cell removal, whereas direct injection of CAR T cells into TNBC and lung tumour models represented an alternative route of application in addition to administration via the medium flow, as it induced strong anti-tumour response. Influence of the incorporated TME-aspects on ROR1 CAR T cell therapy represented by CAF-incorporation and/or TGF-β supplementation was analysed. Presence of TGF-β revealed that the specific TGF-β receptor inhibitor SD-208 improves ROR1 CAR T cell function, because it effectively abrogated immunosuppressive effects of TGF-β in TNBC models. Implementation of CAFs should provide a physical and immunological barrier towards ROR1 CAR T cells, which, however, was not confirmed, as ROR1 CAR T cell function was retained in the presence of CAFs in stromal-enriched microphysiologic 3D lung tumour models. The absence of an effect of CAF enrichment on CAR T cell efficacy suggests a missing component for the development of an immunosuppressive TME, even though immunomodulatory cytokines were detected in co-culture models. Finally, improved gene-edited ROR1 CAR T cells lacking exhaustion-associated genes (PD-1, TGF-β-receptor or both) were challenged by the combination of CAF-enrichment and TGF-β in microphysiologic 3D TNBC models. Results indicated that the absence of PD-1 and TGF-β receptor leads to improved CAR T cells, that induce strong tumour cell lysis, and are protected against the hostile TME. Collectively, the microphysiologic 3D tumour models presented in this work reflect aspects of the hostile TME of solid tumours, engage BLI-based analysis and provide long-term tissue homeostasis. Therefore, they present a defined, scalable, reproducible, standardisable and exportable model for translational research with enhanced predictive value for efficacy testing and candidate selection of cellular immunotherapy, as exemplified by ROR1 CAR T cells.
Das humane Respiratorische Synzytial-Virus (RSV) gilt als wichtiger Krankheitserreger für Säuglinge und Kleinkinder sowie für ältere Personen und immunsupprimierte Patienten. Krankheitssymptome und teils schwerwiegende Verläufe werden dabei eher einer Immunpathogenese zugeschrieben als der Virusvermehrung selbst. Aus Ermangelung eines adäquaten Tiermodells wird häufig das RSV-verwandte Pneumonievirus der Maus (PVM) als Ersatzmodell für schwere Pneumovirusinfektionen verwendet.
In dieser Dissertation wurde zum einen die spatiotemporale Rekrutierung von zellulären Komponenten der angeborenen und adaptiven Immunantwort im Verhältnis zum Verlauf einer PVM-Infektion in immunkompetenten und immunsupprimierten Wirten untersucht. Zum anderen wurde die Pathogenese einer Pneumovirusinfektion anhand des PVM-Modells in Mauslinien mit definierten Immundefizienzen analysiert.
Wie bereits in einer früheren Untersuchung ermittelt, korrelierte die Rekrutierung von CD8+ T-Lymphozyten mit der Viruseliminierung (Frey et al., 2008). B-Lymphozyten wurden aktiv in das Lungengewebe PVM infizierter C57BL/6-Mäuse rekrutiert, wobei sie perivaskuläre und peribronchiale Foki, die ebenfalls CD4+ T-Zellen enthielten, bildeten. Dies könnte auf die Bildung tertiärer lymphoider Gewebe hindeuten. Die Rekrutierung von Zellen der angeborenen Immunantwort (NK-Zellen, neutrophile Granulozyten) geschah parallel bzw. verzögert zur Virusvermehrung und damit eher spät während der Infektion. Die Rekrutierung von eosinophilen Granulozyten erfolgte erst in der Eliminationsphase der PVM-Infektion zusammen mit CD4+-T-Zellen. Zusätzlich wurde ermittelt, dass Alveolarmakrophagen (AMΦ) in vivo mit PVM infiziert und dabei transient depletiert wurden. Die Depletion der AMΦ schien dabei nicht durch Lymphozytenpopulationen zu erfolgen.
Die Charakterisierung der PVM-Infektion bei Mäusen mit definierten Immundefizienzen ergab, dass B-Lymphozyten zur partiellen Viruskontrolle in T-Zell-defizienten Mäusen beitragen und dadurch zur Protektion vor letalen Verläufen bei diesen Mäusen führen. Die Letalität bei diesen Mäusen, insbesondere in Abwesenheit von funktionellen B-Zellen, war mit Kontrollverlust über die Virusvermehrung assoziiert. B-Lymphozyten
2
wurden effizient in das infizierte Lungengewebe von T-Zell-defizienten Mäusen rekrutiert. Das Serum T-Zell-defizienter Mäuse wies eine PVM-neutralisierende Aktivität auf, die mit dem Erscheinen PVM-spezifischer IgM-Antikörper, T-Zell-unabhängig synthetisiert, korrelierte. IgG-Antikörper waren jedoch zu diesen Zeitpunkten (14 d.p.i.) nicht nachweisbar. Dies wurde möglicherweise durch unvollständigen oder verzögerten Reifungsprozess von B-Lymphozyten in T-Zell-defizienten Mäusen reflektiert, da verschiedene Antikörperklassen, wie IgM- und IgG-Antikörper zeitgleich exprimiert wurden.
Eine hohe Heterogenität bzgl. der klinischen Symptome und dem Ausgang der Infektion schien außerdem ein Kennzeichen von PVM-Infektionen unter bestimmten Immundefizienzen zu sein. Der adoptive B-Zell-Transfer in B6.Rag1-/--Mäuse verändert die Krankheitsverläufe nach PVM-Infektion, da einige B-Zell-transplantierte Mäuse ohne klinische Symptome zu zeigen überlebten und andere zwar Gewicht verloren und die Versuchsabbruchkriterien erreichten, aber die Heterogenität der Krankheitsverläufe reduziert war. Adoptiv transferierte B-Lymphozyten wurden außerdem in lymphatische Organe und in infiziertes Lungengewebe rekrutiert und waren in der Lage zu Plasmazellen zu reifen. Es gibt somit erste Indizien, dass B-Zellen zu einem Schutz bei einer akuten PVM-Infektion beitragen.
This work illustrates how the targeted tailoring of supramolecular cavities can not only accomplish high binding due to optimized stereoelectronic shape matches between host and guest but also how molecular engineering of the binding site by a refined substitution periphery of the cavity makes enantiospecific guest recognition and host mediated chirality transfer feasible. Moreover, an enzyme mimic, following the Pauling-Jencks model of enzyme catalysis was realized by the smart design of a PBI host composed of moderately twisted chromophores, which drives the substrate inversion according to the concepts of transition state stabilization and ground state destabilization. The results of this thesis contribute to a better understanding of structure-specific interactions in host-guest complexes as well as the corresponding thermodynamic and kinetic properties and represent an appealing blueprint for the design of new artificial complex structures of high stereoelectronic shape complementarity in order to achieve the goal of sophisticated supramolecular receptors and enzyme mimicry.
Ziel der vorliegenden Arbeit ist es, „Lanfranks ‚Chirurgia parva‘ in der Abschrift Konrad Schrecks von Aschaffenburg“1 anhand der von Ralf Vollmuth in seiner Habilitationsschrift „Traumatologie und Feldchirurgie an der Wende vom Mittelalter zur Neuzeit“ erarbeiteten Strukturvorgabe inhaltlich zu erschließen. Durch die Aufarbeitung verschiedener chirurgischer Fachbücher und Manuale unter Verwendung einer gemeinsamen Strukturvorlage soll ermöglicht werden, medizinhistorische Quellen kritisch-kontrastiv zu vergleichen. Das bedeutet, dass die Quellen zuerst ediert und anschließend gegebenenfalls übersetzt werden müssen. Im nächsten Schritt werden die verwendeten Arzneimittel – pflanzlicher, tierischer, mineralischer Herkunft – identifiziert und bestimmt. Im Anschluss werden Monographien mit den bestimmenden Inhaltsstoffen und Eigenschaften
erstellt. Anhand dieser Pflanzen- und Arzneistoffmonographien, die im Sinne einer Datenbank aufeinander aufbauen, sollte es dann möglich sein, unter modernen pharmakologischen Gesichtspunkten die Wirksamkeit der verwendeten Arzneimittel zu erschließen.
Eine ausreichende Zahl von Quellen, die nach einer gemeinsamen Strukturvorlage bearbeitet wurden, kann es schließlich ermöglichen, zu beurteilen, welche der beschriebenen Anwendungen repräsentativ waren, welche Außenseiterstellung einnahmen oder nur theoretische Ansätze bildeten, die praktisch keine Verwendung fanden.
Ziel dieser Dissertation ist es, etwaige Gemeinsamkeiten und Unterschiede hinsichtlich der Distribution und Intensität von Brandverletzungen bei suizidaler Selbstverbrennung im Freien in Abhängigkeit von der jeweiligen Körperposition zum Auffindezeitpunkt anhand der Aktenlage herauszuarbeiten. Das Studienkollektiv umfasst 38 Fälle
aus 9 deutschen rechtsmedizinischen Instituten, darunter 13 (34,2 %) weibliche und 25
(65,8 %) männliche Suizidenten/-innen im Alter von 18 – 77 Jahren. Neben einer deskriptiven visuellen Analyse erfolgt die Auswertung der Verteilung der Verbrennungen mittels
der Software BurnCase 3D, die es ermöglicht, eine Sortierung der einzelnen Körperbereiche nach deren durchschnittlicher Verbrennungsintensität innerhalb verschiedener
Cluster für die unterschiedlichen Auffindepositionen am Tatort (Rückenlage, Bauchlage,
Seitenlage, Aufrecht, Sitzend) vorzunehmen.
Am ehesten auf das in aufrechter Haltung beginnende Brandgeschehen zurückzuführen ist eine clusterübergreifend auftretende, intensive und nach kranial an Intensität
abnehmende Verbrennung des Halses sowie der lateralen und perioralen Kopfbereiche.
Geringe Verbrennungsfolgen weisen die distalen unteren Extremitäten sowie die Auflageflächen des Körpers auf dem Untergrund auf. Es zeigt sich eine Beeinflussung der lokalen Verbrennungstiefe durch ein hohes Fettgewebevorkommen. Ebenfalls clusterübergreifend können verstärkte Brandwirkungen an den Oberschenkelinnenseiten festgestellt
werden. In Rücken- und Bauchlage liegt zudem eine höhere Verbrennungsintensität an
den Flanken, den Arminnenseiten und im Unterbauchbereich vor. Bei in Seitenlage verbrannten Körpern ergeben sich Hinweise darauf, dass die nach oben gerichtete Körperseite vermehrt Verbrennungen aufweist. In aufrechter und sitzender Position konzentriert
sich der Brandfokus überwiegend auf Torso, Hals und Kopf. Zusätzlich wurde eine Betrachtung des Entstehungsmusters kutaner Hitzerisse durchgeführt. Hier ergaben sich
Übereinstimmungen u.a. mit dem Verlauf der Hautfaltlinien nach Pinkus. Ein Körperschema mit Abbildung der beobachteten Orientierungen der Risse wurde angefertigt.
Die wichtigsten Limitationen ergeben sich aus einer geringen Fallzahl, einer fotografischen Dokumentation, die nicht alle Körperbereiche in ausreichender Qualität und
Detailliertheit abdeckt, sowie dem subjektiven Bias hinsichtlich der Bewertung der Verbrennungsintensitäten.
Im sechsten Semester des Medizinstudiums an der Julius-Maximilians-Universität Würzburg findet das verpflichtende Praktikum „Impfkurs“ statt. Im Rahmen dieses Kurses wurde vom Sommersemester 2020 bis zum Sommersemester 2021 ein standardisierter online Fragebogen erhoben, der unter anderem demographische Daten sowie Expositionsmöglichkeiten gegenüber SARS-CoV-2 im privaten, beruflichen und universitären Umfeld erfragte. Zusätzlich wurde im gleichen Zeitraum der SARS-CoV-2 Serostatus der Medizinstudierenden erhoben und ausgewertet und dieser mit den Daten des Fragebogens zusammengeführt. Dafür wurden Blutproben entnommen, welche im Labor des Instituts für Virologie der Universität Würzburg mittels Western Blot auf IgG/IgM/IgA Antikörper gegen SARS-CoV-2 untersucht wurden.
Hintergrund: Die therapeutischen Optionen für das gering differenzierte (PDTC) und anaplastische (ATC) Schilddrüsenkarzinom sind limitiert, weshalb diese Erkrankungen überwiegend mit einer schlechten Prognose einhergehen. Lenvatinib (LEN) ist ein Multityrosinkinase-Inhibitor, der unter anderem die Fibroblasten-Wachstumsfaktor-Rezeptoren (FGFR) 1-4 inhibiert und zur Therapie des fortgeschrittenen radiojodrefraktären Schilddrüsenkarzinoms zugelassen ist. Es zeigt sich nur ein geringes Ansprechen auf die Monotherapie bei ATCs, wobei neuere Studien eine therapeutische Überlegenheit der Kombination aus LEN und dem PD-1-Inhibitor Pembrolizumab (PEM) beschreiben.
Material und Methoden: Die Expression von PD-L1 wurde in ATC (n=93)- und PDTC (n=47)-Primärtumorgewebe von 1997-2019 aus fünf deutschen (Universitäts-)Kliniken mittels Immunhistochemie analysiert und mit dem Tumor Proportion Score (TPS) quantifiziert. Der Nachweis von FGFR1-4-mRNA wurde bei 31 ATC- und 14 PDTC-Gewebeproben mittels RNAscope In-situ-Hybridisierung quantifiziert. Als Kontrollgruppe wurde normales Schilddrüsengewebe (NT) und Gewebe von papillären Schilddrüsenkarzinomen (PTC) verwendet. Der primäre Endpunkt war das krankheitsspezifische Überleben (DSS).
Ergebnisse: Eine PD-L1-Expression mit einem TPS ≥50% konnte in 42% der ATC- und in 26% der PDTC-Proben nachgewiesen werden. Die mediane PD-L1-Expression war in ATC-(TPS 30%) signifikant höher im Vergleich zu PDTC-Proben (5%; p<0,01) und NT (0%; p<0,001). 53% der PDTC-Proben zeigten eine PD-L1-Expression ≤5%. Die Expression von FGFR-mRNA war in allen Proben sehr gering, wobei die kombinierte FGFR1-4-Expression in PDTC- und ATC-Gewebe im Vergleich zu normalem Schilddrüsengewebe signifikant höher war (jeweils p<0,001). Es ergab sich keine Assoziation zwischen der PD-L1- und FGFR1-4-Expression mit dem krankheitsspezifischen Überleben.
Schlussfolgerung: Eine hohe PD-L1-Expression in einem großen Anteil der ATCs und einem Viertel der PDTCs, könnte auf eine Rationale zur Therapieentscheidung für Immuncheckpoint-Inhibioren hinweisen. Die FGFR-Expression war in allen Schilddrüsenkarzinomen sehr gering. Der klinisch beobachtete Synergismus von PEM und LEN könnte durch immunmodulatorische Effekte hervorgerufen werden.
Among the defense strategies developed in microbes over millions of years, the innate adaptive CRISPR-Cas immune systems have spread across most of bacteria and archaea. The flexibility, simplicity, and specificity of CRISPR-Cas systems have laid the foundation for CRISPR-based genetic tools. Yet, the efficient administration of CRISPR-based tools demands rational designs to maximize the on-target efficiency and off-target specificity. Specifically, the selection of guide RNAs (gRNAs), which play a crucial role in the target recognition of CRISPR-Cas systems, is non-trivial. Despite the fact that the emerging machine learning techniques provide a solution to aid in gRNA design with prediction algorithms, design rules for many CRISPR-Cas systems are ill-defined, hindering their broader applications.
CRISPR interference (CRISPRi), an alternative gene silencing technique using a catalytically dead Cas protein to interfere with transcription, is a leading technique in bacteria for functional interrogation, pathway manipulation, and genome-wide screens. Although the application is promising, it also is hindered by under-investigated design rules. Therefore, in this work, I develop a state-of-art predictive machine learning model for guide silencing efficiency in bacteria leveraging the advantages of feature engineering, data integration, interpretable AI, and automated machine learning. I first systematically investigate the influential factors that attribute to the extent of depletion in multiple CRISPRi genome-wide essentiality screens in Escherichia coli and demonstrate the surprising dominant contribution of gene-specific effects, such as gene expression level. These observations allowed me to segregate the confounding gene-specific effects using a mixed-effect random forest (MERF) model to provide a better estimate of guide efficiency, together with the improvement led by integrating multiple screens. The MERF model outperformed existing tools in an independent high-throughput saturating screen. I next interpret the predictive model to extract the design rules for robust gene silencing, such as the preference for cytosine and disfavoring for guanine and thymine within and around the protospacer adjacent motif (PAM) sequence. I further incorporated the MERF model in a web-based tool that is freely accessible at www.ciao.helmholtz-hiri.de.
When comparing the MERF model with existing tools, the performance of the alternative gRNA design tool optimized for CRISPRi in eukaryotes when applied to bacteria was far from satisfying, questioning the robustness of prediction algorithms across organisms. In addition, the CRISPR-Cas systems exhibit diverse mechanisms albeit with some similarities. The captured predictive patterns from one dataset thereby are at risk of poor generalization when applied across organisms and CRISPR-Cas techniques. To fill the gap, the machine learning approach I present here for CRISPRi could serve as a blueprint for the effective development of prediction algorithms for specific organisms or CRISPR-Cas systems of interest. The explicit workflow includes three principle steps: 1) accommodating the feature set for the CRISPR-Cas system or technique; 2) optimizing a machine learning model using automated machine learning; 3) explaining the model using interpretable AI. To illustrate the applicability of the workflow and diversity of results when applied across different bacteria and CRISPR-Cas systems, I have applied this workflow to analyze three distinct CRISPR-Cas genome-wide screens. From the CRISPR base editor essentiality screen in E. coli, I have determined the PAM preference and sequence context in the editing window for efficient editing, such as A at the 2nd position of PAM, A/TT/TG downstream of PAM, and TC at the 4th to 5th position of gRNAs. From the CRISPR-Cas13a screen in E. coli, in addition to the strong correlation with the guide depletion, the target expression level is the strongest predictor in the model, supporting it as a main determinant of the activation of Cas13-induced immunity and better characterizing the CRISPR-Cas13 system. From the CRISPR-Cas12a screen in Klebsiella pneumoniae, I have extracted the design rules for robust antimicrobial activity across K. pneumoniae strains and provided a predictive algorithm for gRNA design, facilitating CRISPR-Cas12a as an alternative technique to tackle antibiotic resistance.
Overall, this thesis presents an accurate prediction algorithm for CRISPRi guide efficiency in bacteria, providing insights into the determinants of efficient silencing and guide designs. The systematic exploration has led to a robust machine learning approach for effective model development in other bacteria and CRISPR-Cas systems. Applying the approach in the analysis of independent CRISPR-Cas screens not only sheds light on the design rules but also the mechanisms of the CRISPR-Cas systems. Together, I demonstrate that applied machine learning paves the way to a deeper understanding and a broader application of CRISPR-Cas systems.
The WHO-designated neglected-disease pathogen Chlamydia trachomatis (CT) is a gram-negative bacterium responsible for the most frequently diagnosed sexually transmitted infection worldwide. CT infections can lead to infertility, blindness and reactive arthritis, among others. CT acts as an infectious agent by its ability to evade the immune response of its host, which includes the impairment of the NF-κB mediated inflammatory response and the Mcl1 pro-apoptotic pathway through its deubiquitylating, deneddylating and transacetylating enzyme ChlaDUB1 (Cdu1). Expression of Cdu1 is also connected to host cell Golgi apparatus fragmentation, a key process in CT infections.
Cdu1 may this be an attractive drug target for the treatment of CT infections. However, a lead molecule for the development of novel potent inhibitors has been unknown so far. Sequence alignments and phylogenetic searches allocate Cdu1 in the CE clan of cysteine proteases. The adenovirus protease (adenain) also belongs to this clan and shares a high degree of structural similarity with Cdu1. Taking advantage of topological similarities between the active sites of Cdu1 and adenain, a target-hopping approach on a focused set of adenain inhibitors, developed at Novartis, has been pursued. The thereby identified cyano-pyrimidines represent the first active-site directed covalent reversible inhibitors for Cdu1. High-resolution crystal structures of Cdu1 in complex with the covalently bound cyano-pyrimidines as well as with its substrate ubiquitin have been elucidated. The structural data of this thesis, combined with enzymatic assays and covalent docking studies, provide valuable insights into Cdu1s activity, substrate recognition, active site pocket flexibility and potential hotspots for ligand interaction. Structure-informed drug design permitted the optimization of this cyano-pyrimidine based scaffold towards HJR108, the first molecule of its kind specifically designed to disrupt the function of Cdu1. The structures of potentially more potent and selective Cdu1 inhibitors are herein proposed.
This thesis provides important insights towards our understanding of the structural basis of ubiquitin recognition by Cdu1, and the basis to design highly specific Cdu1 covalent inhibitors.