Dickens Undone seeks to reframe what is commonly construed as the periphery of Victorian novels as an expansive, fertile area of ‘undone science.’ The introduction argues that the characters populating this ‘periphery’—often referred to as ‘minor characters’—are the tip of an iceberg of ‘negative knowledge’ in Victorian Studies: knowledge that is systematically presented as not worth gaining. This disciplinary closure, I suggest, is embedded in a centripetal aesthetics that is racialising and heteronormative, and shapes the knowledge that we do produce on a fundamental level. The readings of Martin Chuzzlewit, Dombey and Son, David Copperfield and Little Dorrit that follow seek to generate and trial analytical tools that can help readers appreciate ex-centric elements, in other words, tools that can help ‘get the science done.’ To break with the racialising heteronormative categories of ‘main’ and ‘minor,’ ‘central’ and ‘peripheral’ characters that continue to order our thinking, I propose a critical practice that aims to read lovingly, in Agamben’s interpretation of the term: a critical practice that seeks to ‘want’ a text ‘with all of its predicates,’ including aspects and characters that have been previously dismissed as ‘minor’ or ‘mere details.’ The first two readings look for ways of appreciating two particular qualities in characters that tend to put critics off: lack of structural relevance and what E. M. Forster called ‘flatness,’ respectively. Chapters three and four use these interpretative tools to zoom in on individual characters that have been considered peripheral to David Copperfield and Little Dorrit. Both readings uncover previously overlooked facets of key thematic concerns of these texts—autobiography and imprisonment, respectively—demonstrating how a more loving, less lopsided reading practice can considerably deepen and subtilise critical understanding of a text as a whole. To illustrate the extent to which our centripetal aesthetics have distorted our knowledge of Dickens’s writing, the readings in Dickens Undone pay special attention to one particular group of characters whose systematic marginalisation by the Academy is unusually well-documented: working- and lower-class women and women of (some) economic independence. These characters’ exclusion from the conversation, I argue, has been refigured as a critical fiction: that femininity in Dickens is strictly middle-class. The working-class and working women characters I discuss are (like many others) presented by their texts as explicitly feminine. They point toward a femininity that is much more accommodating when it comes to class and age—a femininity, I suggest, which in this inclusivity and in the face of the absence of women of colour in Dickens’s fiction must be examined as a technology of whiteness.Weniger anzeigen
Three aspects of group 7 isocyanide chemistry were considered in this thesis. First, the reactivity of electron-poor isocyanides with facial tricarbonyl starting materials was investigated. As expected, the reactions with technetium were significantly faster than with rhenium and carbonyl ligands of fac-[Tc(CO)3(CNR)2Cl] (R = tBu, nBu) could be exchanged under thermal conditions forming the key intermediate mer-[Tc(CNp-FArDArF2)3(CNR)2Cl]. The chlorido ligand in this compound can be abstracted using a halide scavenger and replaced by a sixth isocyanide ligand leading to the first defined heteroleptic hexakis(isocyanide)technetium(I) complex : [Tc(CNp-FArDArF2)3(CNnBu)2(CNtBu)][PF6]. CNPhpF was then used to assess the reactivity of electron-poor isocyanides without the sterical strain caused by the flanking rings of the m,m´-terphenyl isocyanide CNp-FArDArF2. The reaction kinetics were even faster once the sterical strain was removed. In both cases, the combination of 99Tc and 19F NMR spectroscopy proved invaluable to monitor the progress of the reaction in solution. The use of 19F NMR was even more important for reaction involving rhenium as the metal center cannot be observed by NMR. The slower reaction rates of the rhenium compounds allowed the facile isolation of intermediate compounds such as fac-[Re(CO)3(CNPhpF)2Br] or trans-[Re(CO)(CNPhpF)4Br], which could both only be spectroscopically observed for technetium. In a second part of the thesis, the reactivity of isocyanides with high-valent phenylimido starting materials was studied. Both electronic and steric factors play a role in the outcomes of the reactions. The electron-deficient CNPhpF was able to cleave the technetium-nitrogen bond and replaced the entire coordination sphere to form a hexakis(isocyanide)technetium(I) complex. Such a high substitution degree was not observed for rhenium and only a [Re(NPhF)(PPh3)(CNPhpF)Cl3] complex could be obtained. On the other hand, the electron-rich m,m´-terphenyl isocyanides CNArDipp2 and CNArTripp2 were able to form bis(isocyanide) complexes with both metals. The reactions with [Re(NPhF)Cl3(PPh3)2] also show, which role fluorine-substitution may have in the coordination chemistry. The non-fluorinated starting material [Re(NPh)Cl3(PPh3)2] is too little soluble for reactions with delicate isocyanides and the introduction of a fluorine atom on the phenylimido ring increases the solubility. Furthermore, this fluorine atom shows small, but significant shifts in 19F NMR resonances, which were used to monitor the progress of such reactions. Moreover, the electron deficient and highly fluorinated CNp-FArDArF2only forms [M(NPhR)Cl3(PPh3)(CNp-FArDArF2)], even though the sterical hinderance of the ligand does not preclude a higher substitution. Remarkably, the IR stretches of all used isocyanides show hypsochromic shift upon coordination on Re(V) and Tc(V) centers. This means, they act exclusively as σ-donors. In the last part of this thesis, the gained knowledge on the influence of steric and electronic parameters on the reactivity of isocyanide ligands was applied to synthesize a functionalizable isocyano ligand. Surface-Averaged Donor−Acceptor Potential (SADAP) parameters showed that the alkyne functionalized isocyanide CNPhpC≡CH should have a similar reactivity to the CNPhpF ligand, which replaces carbonyl ligands under thermal conditions. Indeed, the reaction of (NBu4)[Tc2(µ-Cl)3(CO)6] with CNPhpC≡CH lead to the (hexakis)isocyanide complex [Tc(CNPhpC≡CH)6]+. The latter complex could be “clicked” with benzyl azide using an appropriate copper catalyst. The reaction conditions to form the (hexakis)isocyanide complex were harsh and required an inert atmosphere which precluded equivalent reactions with aqueous 99mTc. The Cu(I) complex [Cu(CNPhpC≡CH)4](BF4) could be readily synthesized and “clicked” under milder conditions. The resulting [Cu(CNPhazole)4]+ can be used as a transmetalation reagent for the synthesis of the hexakis(isocyanide)technetium(I) complex, which is the preferable approach for the synthesis of the technetium complex with the short-lived isotope 99mTc. Alternatively, the uncoordinated ‘Click’ product can be obtained by cleaving the [Cu(CNPhazole)4](BF4) complex with aqueous NaCN. It readily reacts with mer-[Tc(CO)3(tht)(PPh3)2](BF4) (tht = tetrahydrothiophene) under the exchange of the thioether ligand.Weniger anzeigen
SARS-CoV-2 und ZIKV sind zwei neu auftretende Krankheitserreger. Ein wesentliches Werkzeug für die Charakterisierung des viralen Lebenszyklus sind Antikörper. Monoklonale Antikörper (MAbs) sind ein immunologisches Instrument mit vielfältigen Anwendungen in Forschung, Diagnose und Therapie. Die konventionelle Herstellung von MAbs ist jedoch zeitaufwändig, kostspielig und erfordert die Verwendung vieler Tiere und geht außerdem mit einer Belastung der Versuchstiere einher. Alle tierexperimentell arbeitenden Wissenschaftler sind sich der großen Verantwortung bewusst, die sie für das Wohlergehen der Versuchstiere tragen. Obwohl Tierversuche in der Forschung unerlässlich sind, besteht Einigkeit darüber, sie auf ein notwendiges Minimum zu beschränken. Als Richtlinie gilt dabei das ethische Prinzip der „3R“: Replace (Vermeiden), Reduce (Verringern) und Refine (Verbessern). Nach dem 3R-Prinzip zielte dieses Projekt darauf ab, SARS-CoV-2 und ZIKV-spezifische monoklonale Antikörper durch In-Vitro Immunisierung zu erzeugen. In diesem Projekt wurden zellpermeable Carrier-Capside benutzt, die einerseits das Zellpermeabilität vermittelnde TLM-Peptid beinhalten und im Bereich des Spike tips einen insertierten Strep-tag aufweisen. Dies ermöglicht die flexible Beladung mit Antigenen, die an Streptavidin fusioniert sind, so dass zellpermeable VLPs entstehen, die an ihrer Oberfläche mit Antigen beladen sind. Durch die Verwendung dieser Plattformtechnologie, die einen effizienteren Antigentransfer und eine robustere Immunantwort induziert als eine konventionelle Immunisierung mit dem freien Antigen, soll die geringere Effizienz der In-Vitro Immunisierung kompensiert werden. Rekombinante Antigene und VLPs konnten in E. coli hergestellt und durch Affinitätschromatographie gereinigt werden. Dichtegradientenzentrifugation und Elektronenmikroskopie zeigten den Aufbau der vlps und die Beladung mit den Antigenen. Diese Antigen-beladenen Partikel wurden zur In-Vitro Immunisierung von Milz-abgeleiteten Lymphozyten verwendet. Bei der In-Vvitro Immunisierung erfolgt die Immunisierung nicht im Tier, sondern in Kultur. Nach 4 Tagen war die Immunisierung abgeschlossen und die Zellen bereit für die Fusion mit Myeloma Zellen, um Hybridoma herzustellen. Wir haben ein Elektrofusionsprotokoll zur Fusion von B-Zellen mit Myelomzellen erstellt. B-Zellen und Myelomzellen werden über Komplexe aus Biotin- und Streptavidin–gekoppeltem Antigen verknüpft. Dazu wurde eine Biotinylierung von Oberflächenproteinen der Sp2/0-Ag14 Zellen durchgeführt. Fusionsproteine bestehend aus monomerem Streptavidin und ZIKV.E oder spike RBD können an das Biotin auf der Zelloberfläche binden. Auf der anderen Seite kann das Antigen an Oberflächen von B-Zellen binden. Nach Inkubation der B-Zellen mit Myeloma Zellen entstehen Verbindungen zwischen beiden Zellen, was zu einer effizienten Fusion führt. Anschließend erfolgt die Elektrofusion der Zellsuspension in einem Puffer niedriger Ionenstärke. Die monoklonalen Antikörper werden von den Zellen an das Medium abgegeben und können daraus in großen Mengen in vitro gewonnen werden. Durch diesen Ansatz wurden SARS-CoV2-Spike-RBD- und ZIKV.E-spezifische Antikörper-Mabs in vitro erhalten. Die Antikörperbindung wurde durch die Oberflächenplasmonresonanz auf einem Biacore-System charakterisiert. Somit können diese Antikörper zum Nachweis von SARS-CoV2-Spike bzw. ZIKV.E durch Western-Blot- oder Immunfluoreszenzmikroskopie und zur Quantifizierung von SARS-CoV2 S oder ZIKV.E durch spezifische ELISAs verwendet werden. In Übereinstimmung mit dem 3R-Prinzip haben wir ein Protokoll zur In-Vitro Immunisierung und Erzeugung monoklonaler Antikörper entwickelt. Es wurden hochspezifische Antikörper zum Nachweis und zur Quantifizierung von entweder SARS-CoV2-Spike oder ZIKV-Hüllprotein erhalten.Weniger anzeigen
Das Ziel dieser Arbeit war es, die nahe verwandten Spezies V. cholerae und V. mimicus mittels MALDI-TOF MS und den zur Verfügung stehenden Standard-Softwares (flexAnalysis, MALDI Biotyper OC) und deren Tools schnell und sicher zu differenzieren. Später war es möglich, eine weitere Software (ClinPro Tools) und eine zusätzliche Vibrio-spezifische Datenbank (VibrioBase) zu erhalten und diese in die Untersuchungen einzubinden. Zunächst wurden von 62 Vibrio-Isolaten 20 (zehn je Spezies) ausgewählt, um sie auf potentiell speziesdiskriminierende Peaks in der Software flexAnalysis zu untersuchen. Hier war eine interne Kalibrierung der Spektren auf einen gattungsgemeinsamen Peak (4279 Da) vorteilhaft, da sie einheitlich darauf ausgerichtet und Streuungen minimiert wurden. Auffällige Peaks mussten Auswahlkriterien standhalten, um als potentiell speziesdiskriminierend gewertet zu werden. Anschließend wurden diese Peaks anhand der bisherigen 20 und weiterer 42 Isolate validiert. Dabei ergab sich für V. cholerae eine Sensitivität von 97% und eine Spezifität von 100%, für V. mimicus waren es 93% und 97%. Mit den Anwendungen der Software MALDI Biotyper OC konnten keine diskriminierenden Peaks ermittelt werden. Allerdings konnten die Spezies mit der Dendrogramm- und PCA-Funktion gut voneinander unterschieden werden, sofern Kontrollisolate mitgeführt wurden. Parallel wurden von den 42 o.g. Isolaten sowohl Spektren mittels Direkttransfer (BRUKER DALTONIK GmbH, 2013b) als auch mit der Ameisensäure-Extraktion (BRUKER DALTONIK GmbH, 2013a) erstellt und verglichen. Dabei machte sich schnell bemerkbar, dass der Direkttransfer eine erhebliche Einsparung von Arbeitsaufwand, -mitteln und -zeit erbringt. Später wurde mit der Software ClinPro Tools festgestellt, dass sich die bisher gefundenen diskriminierenden Peaks hiermit sehr viel schneller ermitteln ließen. Besonders mit der Funktion, eigene Modelle zu generieren, ergäbe sich künftig mit dem Direkttransfer die Möglichkeit, ein Ergebnis für ein V. cholerae-mimicus-fragliches Isolat (von der Agarplatte bis zum Resultat) innerhalb von etwa 15 min zu erhalten. Allerdings hatte ClinPro Tools die Einschränkung, dass Spektren gleicher Isolate oder von sehr nahe verwandten Spezies, wie z.B. V. metoecus, nicht auffallen und nicht differenziert werden konnten. Bei dieser Problematik stellte sich flexAnalysis zwar als zeitintensiv, aber durch die sehr genaue Spektrenauswertung als geeigneter heraus. Zu einem nochmals späteren Zeitpunkt wurden weitere elf Isolate vom BfR zur Verfügung gestellt, bei denen in vorherigen Untersuchungen widersprüchliche Speziesergebnisse auftraten. Diese Isolate wurden in gleicher Weise, wie die Bisherigen untersucht. In allen drei verwendeten Softwares und deren Anwendungen erhielten sie das Ergebnis V. mimicus. Dies wurde später vom BfR über Genom-Sequenzanalysen bestätigt und es unterstützt die Anwendbarkeit der in dieser Arbeit untersuchten Differenzierungsmöglichkeiten nahe verwandter Bakterienspezies mittels MALDI-TOF MS. Zuletzt wurde die Datenbank VibrioBase in MALDI Biotyper OC hinzugefügt. Es sollte geprüft werden, ob sich mit ihr die untersuchten Spezies besser differenzieren ließen als mit den bisher verfügbaren Datenbanken (BDAL und SR). V. cholerae-Isolate wurden sowohl mit der VibrioBase (+ SR) als auch mit der Bruker BDAL-Datenbank (+SR) zu 100% richtig identifiziert. Die V. mimicus-Isolate wurden zu 89% richtig identifiziert und zu 11% falsch als V. cholerae oder nicht sicher. Wohingegen die BDAL-Datenbank (+SR) nur etwa 20% der V. mimicus-Isolate korrekt differenzieren konnte. Die in dieser Arbeit zufällig gefundenen Isolate der Spezies V. metoecus erhielten immer das falsche Ergebnis V. mimicus, da diese Spezies in den Datenbanken nicht hinterlegt war. Um künftig Routineisolate zügig zu differenzieren, wird empfohlen, V. cholerae-mimicus-fragliche Isolate zunächst per Direkttransfer aufzuarbeiten und mit Vibrio-spezifischen Datenbanken z.B. VibrioBase abzugleichen. Hat der Anwender keine solcher Datenbanken zur Verfügung, kann er eigene Modelle in ClinPro Tools mit den Peaks bei 4025 Da, 7969 Da und 9122 Da für V. cholerae und 7958 Da, 9141 Da, 9477 Da und 9981 Da für V. mimicus erstellen und die Isolate in kurzer Zeit klassifizieren. Andernfalls können diese Peaks selbst in flexAnalysis aufgesucht werden, nachdem die Spektren intern auf den Peak bei 4279 Da kalibriert wurden. Die Spezies V. metoecus konnte nicht differenziert werden, da nur zwei Isolate vorlagen. Allerdings kann ein erfahrener Anwender u.U. die Andersartigkeit dieser Spektren im Vergleich zu V. cholerae- und V. mimicus-Spektren erkennen. Um künftig bei weiteren Spezies mit sehr ähnlichen Spektren, z.B. V. metoecus, spezifische Peaks selbst zu ermitteln, wird empfohlen, die zu untersuchenden Isolate unter standardisierten Bedingungen anzuzüchten und mit der Ameisensäure-Extraktion aufzuarbeiten. Die Suche nach spezifischen Peaks sollte zunächst in ClinPro Tools erfolgen z.B. mit dem Total Average Spektrum, der Gelview Funktion, der ROC Analyse oder einer Kombination daraus. Anschließend können entsprechende Modelle generiert werden. Eine kurze Überprüfung in flexAnalysis sollte trotzdem erfolgen, um auffällige Isolate zu erkennen. Steht ClinPro Tools nicht zur Verfügung, ist ein visueller Abgleich in flexAnalysis auf alleinstehende Peaks oder Peakshifts möglich. Dabei sollte eine interne Kalibrierung aller Spektren z.B. auf einen gattungsspezifischen Peak erfolgen.Weniger anzeigen
Amphiphilic peptide-based biomaterials are of great interest for pharmaceutical and biomedical applications and mainly associated with pronounced biocompatibility and biodegradability. In fact, introducing fluorine-containing amino acids into peptides & proteins offers an unique opportunity to enhance their biophysical properties such as membrane permeability. Through its influence on hydrophobicity and polarity, the degree of fluorination dictates the extent of fluorine-specific interactions on peptide folding and stability, intermolecular interactions, and biological activity. The first study of this doctoral thesis describes the folding, self-assembly, and hydrogelation of single-strand amphipathic peptides with different degrees of fluorination on the amino acid side chains by the iterative incorporation of monofluoroethylglycine (MfeGly), difluoroethylglycine (DfeGly), and trifluoroethylglycine (TfeGly). A combination of experimental and theoretical approaches proved a higher degree of side chain fluorination to promote β-sheet formation and the rheological stability of peptide-based hydrogels in physiological conditions, whereas secondary structure formation was inhibited at a low fluorine content due to fluorine-induced polarity. In a follow-up study, the selective modification of antimicrobial peptides (AMPs) by fluorinated amino acids was investigated. A β-hairpin-forming peptide motif, whose amphipathic structure enables the targeted disruption of bacterial cell membranes, was therefore examined. Extensive MIC screening with Gram-negative and Gram-positive bacteria confirmed highly fluorinated amino acids such as trifluoroethylglycine (TfeGly) or pentafluoropropylglycine (PfpGly) to strengthen the bioactivity of the AMPs through enhanced intrinsic hydrophobicity without causing a simultaneous increase in toxic & hemolytic properties. Numerous studies on the singular incorporation of fluorinated amino acids have been published to date, whereas synthetic peptides with larger or exclusive amounts of these building blocks remained unexplored. That drove the motivation for the herein-described development and characterization of so-called "fluoropeptides". In brief, β-sheet to α-helix or fluorine-induced PPII-helix transitions were observed in SDS-supplemented buffer (pH 7.4). In situ SEIRAS experiments with POPC:POPG-based membrane models functioned to investigate the fluoropeptide’s lipid insertion and (re)folding. Thus, the highest α-helical secondary structure content was found for the nonfluorinated homooligopeptide and decreased in the order of tri-, di-, and mono-fluorination of the side chains. An important focus of this doctoral thesis was the evaluation of biodegradability for especially higher polyfluorinated sequences. In fact, all peptides prepared in this work could be hydrolyzed by various proteases regardless of the fluorine content. In cooperation with the University College Dublin, first data on the microbial digestion of fluorinated peptides and individual amino acids could be generated. The enzyme-catalyzed cleavage of the C-F bond on the side chain for both kind of substrates was, for instance, proven by detection of released fluoride ions in solution. The results of this work will contribute to the rational design and potential application of polyfluorinated peptides, whose enzymatic degradability is going to be of great interest for the future development of fluorinated biomaterials.Weniger anzeigen
Germany, which had long denied its role as a country of immigration (Constant et al., 2012), is today, after the US, the second most popular destination country among immigrants (McAuliffe & Triandafyllidou, 2021). Over the past decades, waves of immigration – to Germany in particular, and to Europe more broadly – have presented societies with numerous new challenges. These challenges exist both at the macro level in terms of social and educational policies to meet the needs of a pluralistic society, and at the micro level concerning how to live together in a culturally and linguistically diversified society (Malik, 2015; Vertovec, 2007b). The overlap between integration and education policies is large, and educational institutions are considered an influential context for immigrant families’ adjustment to the host country (OECD, 2017). In particular, the large achievement gaps between children based on their socioeconomic and immigrant backgrounds have highlighted the need for measures to address inequalities in children’s early years of life (Anders et al., 2012; Kluczniok & Mudiappa, 2019). Accordingly, in recent years, preschools and primary schools have become a greater focus of research and policy. However, it is questionable to what extent these institutions provide an inclusive environment and quality education to children who experience disadvantages due to their social and migration backgrounds. Immigrant parents can provide valuable insight into their children’s formal learning environment in the early years. However, there are limited studies that give immigrant parents a voice and portray their everyday realities. Despite the fact that immigrant parents have high educational aspirations for their children (B. Becker & Gresch, 2016), they experience acculturation stress in the host country, including their children’s schools, due to language and cultural barriers (Jäkel & Leyendecker, 2008; Norheim & Moser, 2020). Moreover, they have been observed to have a desire for their children to develop bicultural competencies in relation to both their heritage and their host countries (Uttal & Han, 2011). Accordingly, immigrant parents have particular identity-related concerns about their children, which affect their beliefs and practices in childrearing. However, we know little about how the characteristics of different contexts influence parents’ social identities and how their social identities shape those contexts. The educational sciences have only recently recognized the relevance of spatial theories in considering issues of identity and inequality (Ferrare & Apple, 2010; Gulson & Symes, 2007a), and there are few empirical studies that apply a socio-spatial theoretical framework. Further, research on immigrant families has not adequately illustrated the relationships between different contexts and usually focuses on only one particular context, such as the home learning environment and school. The study of socio-spatial relations has been mainly limited to the home–school relationship. The linkages between these and broader societal micro and macro contexts that may interact with immigrant parents’ social identities have not been adequately explored. Therefore, this dissertation focuses on this topic and addresses the Turkish-origin community in Germany, the largest immigrant group in the country (Statistisches Bundesamt, 2022). In particular, it examines how Turkish-origin parents of preschool- and primary school-aged children (re-)construct their social identities within home–school–society relational spaces. The dissertation consists of four sub-studies based on the qualitative and quantitative interview data collected within the framework of the Inclusive Education and Social Support to Tackle Inequalities in Society (ISOTIS) project. The quantitative data comprise survey responses from Turkish parents (n = 338) with children aged 3–6 (before primary school) or aged 8–12 (in primary school). The qualitative interview study subjects were drawn from a subsample of the quantitative survey respondents and consisted of 22 mothers. The qualitative data were analyzed utilizing content analysis and included in all four studies of this dissertation. Additionally, Study 4 used a mixed methods design, and content analysis of the qualitative data was used to provide possible explanations for the results of the quantitative data, which were analyzed using (multi-group) regression analysis. Study 1 examined how mothers perceive socio-spatial school and residential segregation and how they relate this issue to the quality of their children’s education. The results showed that mothers living in neighborhoods with high immigrant populations were largely dissatisfied with the quality of their children’s education. Respondents’ concerns about their children being marginalized in a native-dense environment, as well as concerns about their children’s ethnic identity in the context of their potential ‘Germanization,’ were cited as reasons for choosing an immigrant-dense or ethnically and socially diverse school and neighborhood. Despite the fact that some respondents complained about segregation tendencies on the part of the native population, the data showed that middle-class Turkish families, in particular, use similar strategies to raise their children in native-dense environments, even though they ascribe a high value to social diversity. The perceived high educational quality of schools in these neighborhoods was also identified as an influential factor. Moreover, the results indicated not only segregation between schools but also within schools, i.e., the creation of separate classroom groups in primary schools for children from native and/or middle-class families. Study 2 investigated mothers’ perceptions and experiences related to their language use at the intersection of their ethnocultural identities in home–school–society relational spaces. The results showed that the respondents’ linguistic competencies and the value they place on the German language, and their heritage language coincide extensively with their ethnocultural identities, which are mirrored in their ethnolinguistic upbringing beliefs and practices. Parents reported how language barriers affected their parenting (e.g., parental involvement, parent–child relationship) as well as their sense of belonging to the host country (e.g., everyday discrimination) and emphasized experiencing parental stress. Some parents also pointed out that while they did not face a language barrier, symbolic boundaries between them and the native population persisted (e.g., the misconception that women wearing headscarves have little knowledge of German). Regardless of their own German language skills, the parents placed great importance on their children’s German language development, which they saw as a source of success in the host country. Parents were particularly inclined to raise their children bilingually because they viewed their heritage language as an important resource for developing their children’s heritage ethnocultural identity and for enhancing the quality of parent–child interactions. Yet dynamics of inclusion and exclusion in school and society toward their heritage language, as well as the extent to which their linguistic support needs were recognized, appeared to be critical in influencing their social identities in the host country and thus their parenting within the home space. Study 3 addressed the ethnoreligious identities of immigrant mothers within home–school–society relational spaces. The findings showed that parents’ ethnoreligious identities make the home space religiously congruent with or separated from the school and societal space. Their desire to integrate into German society and to ensure that their children received high-quality education and were not marginalized in a non-family environment motivated parents to create congruent spaces (e.g., celebrating Christian festivals at home, parental involvement in Christian celebrations at school, enrolling their children in a church-run preschool). Conversely, some respondents chose contextually separate parenting approaches as a way to maintain their children’s strong religious affiliation. In addition, narratives showed that inclusive (e.g., teachers collaborating with minority parents on their religious celebrations, using interreligious pedagogical practices) and exclusive (e.g., teachers’ cultural prejudice, the perception that some preschools refused to enroll minority children) approaches in schools appeared to be closely linked to the societal space in terms of attitudes toward religious minorities. These spaces seemed to reproduce each other, influencing the ethnoreligious identities of the parents that were reflected in the home space. Thus, they also influenced parents’ beliefs and practices with regard to ethnoreligious upbringing. Finally, Study 4 was conducted to identify the relationship between Turkish immigrant parents’ perception of their children’s school climate and their life satisfaction in Germany. In addition, how this relationship varies depending on the immigrant generation of the parents (first vs. second generation) and the school level of their children (preschool vs. primary school) was investigated. Applying a mixed methods research in Study 4, an explanatory sequential design was used. Thereby, the qualitative interviews were used to further interpret the quantitative research findings. The results of the quantitative survey revealed that life satisfaction in Germany was predicted by the way parents perceived the children’s school climate. While the relationship was significant for both generations, it was stronger for second-generation parents. Further, the relationship was significant only for parents with children attending primary school. The qualitative research findings suggested that there was a high degree of overlap between perceived inequalities in school and in society. These included the sense of injustice (particularly in primary schools), the extent to which an inclusive school climate has been created, and the collaboration of schools with immigrant parents. In conjunction with the quantitative research findings on life satisfaction among Turkish families, this could potentially have implications for immigrant parents. Taken together, the present dissertation highlights the significance of socio-spatial relational theory approaches, which have been largely overlooked in educational sciences, and emphasizes such approaches’ power in portraying immigrant parents’ social identities. Accordingly, this dissertation seeks to contribute theoretical developments, as well as further concrete empirical research, for the exploration of the complex perceptions and experiences of immigrant families within and across various contexts. Moreover, it provides valuable insights for the inclusive pedagogical approaches in preschools and primary schools, as well as educational and social policies aiming to create inclusive environments in their societies.Weniger anzeigen
Psoriasis ist eine chronisch-entzündliche Erkrankung, die außer der Haut und den Nägeln auch die Enthesen und die Gelenke betreffen kann. Durch die Fortschritte im Verständnis der Immunpathogenese der Psoriasis wurden neue hochwirksame gezielte Therapien entwickelt. Diese neuen Therapien ermöglichen individuelle Therapiekonzepte für die Betroffenen. Solche personalisierten Therapien garantieren die höchste Wirksamkeit mit den geringsten Nebenwirkungen. Die TNFα-Inhibitoren sind die ersten gezielten Therapien für Psoriasis. Darüber hinaus bietet die Entwicklung von Antikörpern gegenüber IL-12/IL-23, IL-17 und IL-23 mehr Therapiemöglichkeiten für Psoriasis. In dieser Arbeit wurde die Anwendung von den verschiedenen Klassen von Biologika (Adalimumab, Brodalumab und Ustekinumab) bei Psoriasispatienten:innen in besonderen Situationen untersucht. Das Ziel dieser Arbeit war die Unterstützung der Therapieentscheidung bei Psoriasispatienten:innen basierend auf einem klinischen Profiling.Weniger anzeigen
Infections by gastrointestinal nematodes mandate an effective type 2 response for the parasite clearance. In line with the cross-regulatory nature of Th1 lineage specifying factors on the differentiation of Th2 cells seen at the molecular level, strong type 1 activity resulted by inflammation associated with senescence, specific genetic predisposition and co-infections with intracellular pathogens exacerbate the Th2 responses resulting in poor resistance in nematode infections. Despite reported cross-regulation, the Th1 and Th2 pathways are not mutually exclusive as polarization with IFN-g, IL-12 and IL-4 results in the generation of T-bet and GATA-3 co-expressing Th2/1 cells in vitro. Th2/1 cells are also induced naturally in nematode infections (Affinass et al., 2018; Bock et al., 2017; Peine et al., 2013). In the current study we demonstrate that the IFN-g competence progressively rises with the age of uninfected BALB/c mice displaying high resistance to nematode infection. The elevated type 1 bias in 5-10 months old compared to 2-3 months old mice resulted in poor parasite control manifested by higher female fecundity in the mature cohort infected with H. polygyrus. The poor resistance was accompanied by stronger generation and mucosal accumulation of Th2/1 hybrid cells and elevated proportions of parasite specific IFN-g producing cells. Substantiating the above findings, restriction of IFN-g availability in the priming phase of nematode infection led to improved resistance coinciding with sharp reduction in systemic and mucosal Th2/1 cells and a near complete absence of parasite specific IFN-g producing cells. Conversely, supplementation of early IFN-g availability led to impaired parasite control associated with robust expansion of Th2/1 cells and a significant rise in IFN-g producing cells in parasite specific T cell pool. Importantly, elevated IFN-g availability did not inhibit classical Th2 cells in the long run and rather promoted an accumulation of systemic GATA-3+ Teff cells in IFN-g treated BALB/c mice. The increased parasite egg production upon IFN-g treatment was traced back to the increased fitness of the L4 larvae maturating in the gut of IFN-g treated mice. In line with the findings in differently aged mice, C57BL/6 mice genetically predisposed to higher susceptibility in H. polygyrus infection more rapidly accumulate Th1 cells at steady state compared to resistant BALB/c mice. The elevated type 1 activity in C57BL/6 mice translated to greater accumulation of small intestinal Th2/1 cells post infection and poor resistance compared to BALB/c mice. However, the stark differences seen between the strains at younger age leveled out in older mice due to increased IFN-g competence and increased bias in favor of Th2/1 cells in mature BALB/c mice. Restricting IFN-g availability in C57BL/6 mice led to increased resistance thereby substantiating the significance of IFN-g in differential susceptibility across inbred lines. Overall, our findings report an age-dependent reduction in anti-nematode type 2 immunity resulted by steady state accumulation of IFN-g competent effector cells in the vertebrate host.Weniger anzeigen
Eps15 (epidermal growth factor receptor pathway substrate 15) homology domain containing proteins (EHDs) comprise a family of dynamin-related ATPases. The four mammalian members of this family (EHD1-4) are involved in various endocytic and membrane trafficking pathways. Structural studies revealed that EHDs assemble at the surface of membranes to form ring-like filaments. Assembly on membranes was shown to stimulate the ATPase activity. In case of EHD2, ring-like oligomers were proposed to stabilize the neck of caveolae, which in turn regulates cellular fatty acid uptake. The aim of this thesis was the identification of small molecule inhibitors that modulate EHD2 function and therefore cellular fatty acid uptake. Until now, there are no known inhibitors for EHD proteins. To this end, I optimized a malachite green-based ATPase assay to be robust and reproducible for a high-throughput setup. Drug screening was then employed to identify small molecules that inhibit the liposome-stimulated ATP hydrolysis of EHDs. Since EHD2 showed only a low ATPase activity, I initially screened for inhibitors against the closely related homologue EHD4. Validated hits were subsequently evaluated for inhibition against EHD2 in an HPLC-based setup. In this way, I identified chemical compounds that inhibited the ATPase activity of EHD4 and EHD2, and validated them in different biochemical assays. Interestingly, two of these small molecules were found to increase and decrease lipid droplet size in a cell-based assay. I also identified three inhibitors that were specific to EHD4 and did not interfere with the ATPase of EHD2 and the GTPase activity of Drp1, which was used as a control. Another exciting finding in this project were discovery of two compounds that accelerated the liposome-stimulated GTPase activity of Drp1. The identified inhibitors may have future applications to explore the function of EHDand Drp1-dependent cellular signaling pathways. Furthermore, they may be developed as therapeutic agents. Finally, my assay optimizations can be used to systematically and efficiently identify inhibitors for other dynamin superfamily membersWeniger anzeigen
When we observe a scene in our daily lives, our brains seemingly effortlessly extract various aspects of that scene. This can be attributed to different aspects of the human visual system, including but not limited to (1) its tuning to natural regularities in scenes and (2) its ability to bring different parts of the visual environment into focus via eye movements. While eye movements are a ubiquitous and natural behavior, they are considered undesirable in many highly controlled visual experiments. Participants are often instructed to fixate but cannot always suppress involuntary eye movements, which can challenge the interpretation of neuroscientific data, in particular for magneto- and electroencephalography (M/EEG). This dissertation addressed how scene structure and involuntary eye movements influence the extraction of scene and object information from natural stimuli. First, we investigated when and where real-world scene structure affects scene-selective cortical responses. Second, we investigated whether spatial structure facilitates the temporal analysis of a scene’s categorical content. Third, we investigated whether the spatial content of a scene aids in extracting task-relevant object information. Fourth, we explored whether the choice of fixation cross influences eye movements and the classification of natural images from EEG and eye tracking. The first project showed that spatial scene structure impacts scene-selective neural responses in OPA and PPA, revealing genuine sensitivity to spatial scene structure starting from 255 ms, while scene-selective neural responses are less sensitive to categorical scene structure. The second project demonstrated that spatial scene structure facilitates the extraction of the scene’s categorical content within 200 ms of vision. The third project showed that coherent scene structure facilitates the extraction of object information if the object is task-relevant, suggesting a task-based modulation. The fourth project showed that choosing a centrally presented bullseye instead of a standard fixation cross reduces eye movements on the single image level and subtly removes systematic eye movement related activity in M/EEG data. Taken together, the results advanced our understanding of (1) the impact of real-world structure on scene perception as well as the extraction of object information and (2) the influence of eye movements on advanced analysis methods.Weniger anzeigen
We begin this thesis with a discussion of problems from geometry and combinatorics, to which methods from equivariant algebraic topology have been successfully applied in the past.
The generalised Nandakumar & Ramana~Rao problem (due to Karasev, Hubard, & Aronov and Blagojević & Ziegler) asks whether given a full-dimensional compact convex body K in R^n, n-1 continuous real functions on the space of all full-dimensional compact convex bodies in R^n and a natural number m, one can always find a partition of K into m convex pieces of equal volume such that the value of each function is equal on all the pieces of the partition.
Inspired by this problem and recent parameterised generalisations of mass partition types by several groups of researchers, we formulate a parameterised version of the Nandakumar & Ramana~Rao problem, where we aim to equipart j>n-1 functions, but are allowed to choose a convex body K from some family parameterised by a vector bundle E over a CW-complex B.
After we make the notion of "parameterised by the vector bundle E'' precise in Chapter~II, we follow the strategy developed by Karasev, Hubard & Aronov to formulate a topological criterion for the existence of solutions to the parameterised Nandakumar & Ramana Rao problem. Due to the limitations of our topological methods, we restrict our attention to the case when m equals some prime p.
Chapter~III contains a brief overview of various standard algebraic topology results that we use extensively in the later chapters.
In Chapter~IV we extend the results of Jaworowski concerning Fadell-Husseini indices of sphere bundles, equipped with free fibrewise action of the cyclic group Z/Z_p, by considering the symmetric group S_p. Next, we compute the index of the fibrewise configuration space Fconf(p,E) of p distinct points with respect to S_p in the case of vector bundle E of an odd rank. In the case when E has an even rank, we provide bounds on the index, showing that the upper bound is tight in some cases. Then we change the group that acts on E, and compute the index of the space Fconf(p, E) with respect to cyclic group action in the special case when E admits two linearly independent nowhere zero sections.
In Chapter~V we use these computations to find a partial solution to the parameterised Nandakumar & Ramana~Rao problem. For any pair of a vector bundle E and a prime p, we describe a range of j such that the parameterised Nandakumar & Ramana~Rao has a solution for the family of convex bodies parameterised by E, the desired number p of pieces in partition and a choice of j appropriately defined continuous functions. Finally, we apply these computations to the case of tautological bundles over the Grassmannians.Weniger anzeigen
The function of non-coding RNA sequences is largely determined by their spatial conformation. This is the secondary structure of the molecule, which is formed by Watson–Crick interactions between nucleotides. Hence, modern RNA alignment algorithms routinely take structural information into account. Essential tasks for discovering yet unknown RNA families and inferring their possible functions are the structural alignment of RNAs and the subsequent search of the derived structural motifs. These tasks demand a lot of computational resources, especially for aligning many long sequences, and it therefore requires efficient algorithms that utilize modern hardware when available. A subset of the secondary structures contains pseudoknots, which are overlapping interactions that add additional complexity to the analysis and are often ignored in available software.
In this thesis, I present LaRA 2 and MaRs, two SeqAn-based software tools that implement algorithms for finding sequence-structure motifs in genomic sequences. In contrast to other programs, my tools can handle arbitrary pseudoknots. They use multithreading for parallel execution and are implemented in modern C++ code for maximal longevity and performance.
LaRA2 is significantly faster than comparable software for accurate pairwise and multiple alignments of structured RNA sequences. It uses a new heuristic for computing a lower boundary to the solution and employs vectorization techniques for speeding up the time-critical parts of the algorithm.
MaRs can be applied in a workflow right after LaRA2 and derives sequence-structure motifs from the structural alignments. The motifs are descriptors of the RNA sequences’ properties and drive the search for homologs in genomic sequences. MaRs employs a bidirectional index on the genomic sequences and an optimized multithreaded search strategy for finding the matches really fast. The use of a thread pool, effective pruning strategies, and a low memory footprint ensure that MaRs is capable of processing extremely large data sets.Weniger anzeigen
Climate change, antibiotic resistances and environmental pollution are growing threats. Therefore, finding alternatives for fossil resources and discovery of new pharmaceuticals grows more important every day. Natural compounds and their in vivo production pathways proved to be a possible solution to overcome those problems. Optimized microbial hosts can serve as sustainable production platforms for various compounds as it is done for penicillin since many years. The first research topic of this thesis are borneol dehydrogenases, enzymes which convert borneol to camphor. Enantiomerically pure camphor has numerous applications in cosmetic, pharmaceutical, and chemical industry. Thus, enantioselective borneol dehydrogenases would be an attractive candidate to achieve enantiomerically pure camphor. To better understand the differences of enantioselective and unselective borneol dehydrogenases we solved the structures of two selective borneol dehydrogenases from Salvia rosmarinus and Salvia officinalis using X-ray crystallography and cryo-electron microscopy. The obtained structures were compared to the previously solved structure of the unselective borneol dehydrogenase of Pseudomonas sp. TCUHL1. The second focus of this thesis are terpene synthases, a class of enzymes responsible for the cyclization of linear terpene precursors. The products of terpene synthases are interesting candidates for the chemical and pharmaceutical industry due to their diverse characteristics and properties. Latest advances in genome sequencing enabled the discovery of many new and diverse terpene synthases from various organisms. We report on the discovery of two terpene synthases from Coniophora. puteana, Copu5 and Copu9, that not only have identical product profiles, but also show high yields in an optimized Escherichia coli strain. Main product of both enzymes is (+)-δ-cadinol that has been shown to have cytotoxic effect on MCF7 cells and could be used as a new and sustainable anti-tumor drug. To investigate their properties and gain deeper understanding into their function, we attempted to crystallize and biochemically characterize Copu5 and Copu9.Weniger anzeigen
One of the great societal challenges of today is the fight against diseases which reduce life expectancy and lead to high economic losses. Both the understanding and the addressing of these diseases need research activities at all levels. One aspect of this is the discovery and development of tool compounds and drugs. Tool compounds support disease research and the development of drugs. For about 20 years, the discovery of new compounds has been attempted by screening small organic molecules by high-throughput methods. More recently, X-ray crystallography has emerged as the most promising method to conduct such screening. Crystallographic fragment-screening (CFS) generates binding information as well as 3D-structural information of the target protein in complex with the bound fragment. This doctoral research project is focused primarily on the optimization of the crystallographic fragment screening workflow. Investigated were the requirements for more successful screening campaigns with respect to the crystal system studied, the fragment libraries, the handling of the crystalline samples, as well as the handling of the data associated with a screening campaign. The improved CFS workflow was presented as a detailed protocol and as an accompanying video to train future CFS users in a streamlined and accessible way. Together, these improvements make CFS campaigns a more high-throughput method, offering the ability to screen larger fragment libraries and allowing higher numbers of campaigns performed per year. The protein targets throughout the project were two enzymes and a spliceosomal protein-protein complex. The enzymes comprised the aspartic protease Endothiapepsin and the SARS-Cov-2 main protease. The protein-protein complex was the RNaseH-like domain of Prp8, a vital structural protein in the spliceosome, together with its nuclear shuttling factor Aar2. By performing the CFS campaigns against disease-relevant targets, the resulting fragment hits could be used directly to develop tool compounds or drugs. The first steps of optimization of fragment hits into higher affinity binders were also investigated for improvements. In summary, a plethora of novel starting points for tool compound and drug development was identified.Weniger anzeigen
The aim of this dissertation is to better understand Roman grand strategy by analyzing imperial policy in a single province, Lower Germany, and during a particular time period, from the reign of Augustus to that of Hadrian. Despite the local—and, hence, limited— approach, this method lends itself to broader conclusions. On the one hand, examining closely the development and defense of this area— the edge of the Roman Empire’s military territory on the European continent’s northwest— helps to compare and contrast policies carried out in other frontier provinces. Hence, one can scrutinize, confirm, or modify broad, general theses of imperial defense and grand strategy, such as that of Edward Luttwak. On the other hand, Germania Inferior, despite the small extension of its territory, had an outsized military and strategic importance. Emperors often visited the province, and its troops played crucial roles in the conquest and upkeep of Britain and in the later reinforcement of the Danube garrisons. As such, an analysis of Lower German defense—and of troop movements in and out of the province— is inevitably linked with the broader study of Roman grand strategy proper.
Since Roman Lower Germany was heavily militarized, the purely military component of grand strategy, which included constant campaigns of limited scope beyond the Rhine, became intertwined with a political component. The Rhine armies and its commanders became essential players in the dangerous game of imperial politics. The diplomatic component played a role insofar as there were alliances—often shifting, sometimes broken— with tribes and kingdoms beyond the empire’s borders. And, as Lower Germany became further integrated into the Roman imperial structure over time, the area’s economy developed considerably, even if it remained mostly a peripheral province.
For both emperors and legates, ruling Lower Germany involved the complex issue of incorporating the allied, native Batavians into the Roman imperial structure. The extraordinary status of this remarkable, warrior people— at once fiercely loyal to the emperor as the core of his personal bodyguard and partially independent from Rome in their distant domains—sheds light on the Romans’ practice of grand strategy. This applies especially in terms of the simultaneous use of both direct and indirect rule, even within a single province.Weniger anzeigen
It is incumbent on scholars of Arabic studies and Islamic studies who deal with manuscripts to understand pre-modern Arabic scribal practices. This thesis aims to improve our understanding of two aspects of Arabic scribal practices from the third/ninth-fourth/tenth centuries: the paratexts of manuscripts and the elements that help establish clarity and correctness. The study of the paratexts includes the title page, the introductory section, and the colophon. Regarding elements that help establish clarity and correctness, this thesis pays attention to the use of diacritical points and vowels, the cancellation of dittographies, the insertion of omissions, and the methods of preventing and correcting text mistakes. This thesis also analyzes the collation process and how it is marked in the manuscripts. The methodology of this study is to synthesize the normative sources that discuss these elements of scribal practice and then use the findings of this analysis on a selection of manuscripts.Weniger anzeigen
Radicals play a pivotal role in nature and are involved in many biochemical processes. However, until the late 20th century only minor attention was given to single electron processes in synthetic organic chemistry, due to the persistent notion of being difficult to control. With the development of new synthetic approaches to access such reactive open-shell intermediates in a practical fashion, radical chemistry has gained renewed interest. Photoredox catalysis (PRC) has emerged as the cornerstone in accessing these reactive open-shell intermediates under mild conditions. Key to the success of these strategies is the ability of chromophores to harvest visible light and reach long-lived excited states. Subsequently, the excited photocatalytic species can activate intermediates or reagents via single electron transfer (SET), energy transfer (ET), or hydrogen atom transfer (HAT) to yield radicals and enable chemical transformations. The mechanism of such photocatalytic systems often includes multiple catalytic species and reagents, which are actively involved in the catalytic cycle and render mechanistic investigations complicated. State-of-the-art methodologies to investigate photocatalytic systems mainly focus on the properties of the excited state species and consecutive quenching interaction with reagents, catalysts or intermediates. A more holistic picture of the overall process can be acquired via in situ monitoring techniques (Chapter 4). The value of real-time monitoring for gaining mechanistic insights was demonstrated during the development of a photocatalytic benzyl ether cleavage (Chapter 9). Due to their high stability, benzyl ethers are commonly used protecting groups in carbohydrate and natural product syntheses, though commonly utilized harsh deprotection strategies with poor functional group tolerance render them typically unattractive for multistep organic synthesis. Upon visible light irradiation, 2,3-dichlor-5,6-dicyano-1,4-benzoquinone (DDQ) reaches a highly oxidizing, long-lived excited triplet state (DDQ*), capable of oxidative cleavage of benzyl ethers.
A combination of DDQ and tert-butyl nitrite (TBN) cleaved benzyl groups from monosaccharides under ambient atmosphere and visible light irradiation with high functional group tolerance. Real-time monitoring using LED-NMR spectroscopy gave insights in the crucial role of TBN and light. The scale-up of light promoted reactions is typically detrimental to the efficiency of photocatalytic reactions, due to poor light penetration. Careful optimization of the reaction conditions for photooxidative debenzylations was required to access a deprotection methodology applicable on the gram scale (Chapter 6). The facile access to reactive open-shell intermediates enabled by photocatalysis has led to a myriad of new synthetic approaches, including photoredox catalyzed cross-coupling reactions. This is achieved using a combination of nickel and noble metal photocatalysts (PC). A more sustainable alternative to commonly used expensive and homogeneous iridium- and ruthenium polypyridyl complexes was found in graphitic carbon nitrides (gCN). The ability of CN-OA-m in combination with a nickel complex was showcased in an etherification and extended to the coupling of aryl iodides with thiols (Chapter 8). In situ IR-monitoring was applied for detailed kinetic analysis of the developed semi-heterogeneous system and the state-of-the-art photocatalyst tris(2-phenylpyridine)iridium(III) on a model O-arylation reaction. This indicated that different photocatalysts can result in different mechanistic scenarios, that result in the same product (Chapter 7). Incorporating fluorine into organic scaffolds increases the compounds physicochemical properties, such as lipophilicity and metabolic stability, resulting in improved active pharmaceutical ingredients and agrochemicals. Hence, the development of new safe and simple fluorination methodologies is of interest. A divergent benzylic radical fluorination reaction, initiated via a charge transfer complex that does not require visible-light activation, selectively yielded either benzyl fluorides or α-fluorophenylacetic acids depending on the conditions (Chapter 5). Charge transfer complex mediated in situ generation of a highly reactive radical species enabled hydrogen atom transfer (HAT) as well as single electron transfer (SET), solely depending on the pKa of the phenylacetic acid starting material.Weniger anzeigen
Der Dissertation liegt die übergreifende Frage zugrunde, unter welchen Bedingun-gen sich Lehrkräfte auf offene Lernsettings wie das Freie Explorieren und Experimentieren (FEE) einlassen. Im Rahmen einer Interventionsstudie wurde untersucht, inwiefern schulische Rahmenbedingungen und persönliche Faktoren von Lehrkräften die Implementation innovativer, geöffneter Lehr-Lernformen beeinflussen. Den theoretischen Rahmen für die Untersuchung bilden (u.a.) das Konzept des FEEs, die Persönlichkeits-System-Interaktionen Theorie (PSI) und die Selbstbestimmungs-theorie (SDT). Die qualitative Erhebung umfasste eine Stichprobe von neun Grundschullehrkräften und wurde in einem PRE-INTER-POST-Design durchgeführt. Die Auswertung der Daten erfolgte mit der inhaltlich strukturierenden qualitativen Inhaltsanalyse. Die Ergebnisse der Untersuchung zeigen, dass es im Wesentlichen persönliche Fak-toren der Lehrkräfte sind, die die Einführung und Umsetzung der geöffneten Unter-richtsform FEE beeinflussen. So erweisen sich individuelle Selbstkompetenzen, motivationale Orientierungen und die Selbststeuerungsfähigkeit der Lehrkräfte als zentrale Schaltstellen für den Umgang mit der Herausforderung, den eigenen Unterricht zu öffnen. Es zeigt sich, dass ein hohes Professionswissen, die Fähigkeit zum Selbstwachstum und eine klare Autonomieorientierung bedeutsame Gelingensbe-dingungen für die Öffnung des Unterrichts darstellen. Die Ergebnisse der Studie zeigen auch, dass sich ein der Situation angemessenes professionelles pädagogisches Handeln mit der Zeit entwickeln und verändern kann.Weniger anzeigen
The respiratory system is composed of different tissues with their respective cell types that together work in concert to perform air conductance and gas exchange. With the advent of single-cell RNA-sequencing (scRNA-seq), it is now possible to comprehensively interrogate the function of each individual cell in homeostatic and diseased states. In this dissertation, various roles of epithelial, mesenchymal, and immune cell types of the respiratory system in idiopathic pulmonary fibrosis (IPF) and corona virus disease 2019 (COVID-19) were investigated with scRNA-seq.
IPF is a chronic interstitial lung disease characterized by the progressive scarring of the lung parenchyma. Previous studies that surveyed the cellular landscape of IPF lungs utilized explant lungs that reflect end-stage fibrosis. To uncover disease mechanisms of airway cell types in early-stage fibrosis, air-liquid interface (ALI) cultures of primary cells taken from newly diagnosed IPF patients were used. This identified proinflammatory epithelial cells, profibrotic basal cells, and primed fibroblasts as early-stage drivers of IPF. Treatment with antifibrotic compounds nintedanib, pirfenidone, and saracatinib fail to completely ameliorate the identified signatures.
With the emergence of the COVID-19 pandemic and its extensive public health burden, it was imperative to understand the molecular mechanisms of viral entry and disease pathology to identify potential risk factors and therapeutic targets. In the early stages of the pandemic, viral entry factors ACE2, TMPRSS2, and FURIN were found to be expressed by a transient secretory cell type (differentiating from secretory to ciliated cell) of the airway mucosa and by alveolar type 2 cells of the alveolar epithelium. With further investigation of severe COVID-19, the early-stage of COVID-19 infection characterized itself with a hyperactivated immune response mediated by proinflammatory macrophages. On the other hand, late-stage COVID-19, especially those with acute respiratory distress syndrome (ARDS), was characterized by an accumulation of profibrotic macrophages and activated myofibroblasts that drove pulmonary scarring and fibrosis.
Although IPF and COVID-19 are different diseases by their own right, they share a commonality in aberrant wound healing responses. Both diseases are characterized by tissue inflammation that is followed by a profibrotic phase. Unlike in IPF where the tissue remodeling is progressive and chronic, COVID-19 ARDS-associated fibrosis undergoes a resolution phase. Future studies comparing the cellular and transcriptional landscape of both conditions in early and late stages of disease will uncover pathogenic mechanisms and therapeutic targets of lung fibrosis.
The application of high-resolution transcriptomic profiling techniques such as scRNA-seq permits the interrogation of individual cell types and their direct contribution to the development of diseases. Moreover, it allows the comparison and transfer of identified pathomechanisms across different pulmonary diseases and, in doing so, provides deeper and generalizable insights. As this field continues to evolve, it will undoubtedly continue to provide a deeper understanding of respiratory diseases.Weniger anzeigen
Biopolymers self-assemble generating dynamic and complex functional materials that carry out sophisticated tasks. Nature has been a source of inspiration for chemists to create artificial analogs that mimic biopolymer self-assembly. In contrast to peptides and DNAs, carbohydrates are less understood at the molecular level and therefore have rarely been employed as scaffolds to construct self-assembling materials using bottom-up approaches. To date, carbohydrates’ potential in supramolecular chemistry remains mostly untapped. In this thesis, I established structure-property correlations for oligosaccharides and then translated this knowledge into design principles to access self-assembling carbohydrate materials. The use of non-natural monosaccharides and bottom-up approaches were central to deeply understand and design synthetic carbohydrate materials. In Chapter 2, I developed synthetic routes to fluorinated monosaccharide building blocks (BBs) and employed these BBs to assemble a broad collection of complex fluorinated glycans using Automated Glycan Assembly (AGA). Fluorination was exploited as a method to manipulate the hydrogen bonds of cellulose, a polysaccharide with high propensity to crystallize. The subtle role of the substitution pattern and position of the fluorine atom was investigated using X-ray diffraction analysis (XRD). In the second part of Chapter 2, I explored the use of fluorinated glycans as NMR probes. First, 19F-labelled glycans served for structural analysis via NMR revealing the tendency of some oligosaccharides to adopt helical conformations. Last, 19F-labelled Lewis antigens, a class of biologically relevant glycans, were employed to study their binding to proteins and to monitor in real-time enzymatic reactions. In Chapter 3, I developed a bottom-up approach to study the self-assembly and the chirality of supramolecular carbohydrate materials. In the first part, I employed a simple disaccharide that self-assembles into helical fibers to study the transfer of chirality across scales. Site-specific modifications identified key non-covalent interactions stabilizing the assembly. In the second part, I translated the bottom-up approach to a more complex natural polysaccharide and used synthetic oligomers to understand chirality transfer across scales in cellulose. Synthetic D- and L-cellulose oligomers were found to assemble into platelets with controlled dimensions that further aggregate into bundles, displaying chiral features directly connected to their monosaccharide composition. The insertion of L-Glc units in the sequence of D-Glc cellulose oligomers drastically impacted macroscopic properties such as solubility, crystallinity, and chirality of bundles. In Chapter 4, I presented the rational design and synthesis of a glycan adopting a stable secondary structure, challenging the common belief that glycans are not capable of folding due to their flexibility. By combining natural glycan motifs, stabilized by a non-conventional hydrogen bond and hydrophobic interactions, I designed a glycan hairpin, a secondary structure not present in nature. AGA enabled rapid access to synthetic analogs, including site-specific 13C-labelled ones, for NMR conformational analysis. Structural analysis via NMR unequivocally confirmed the folded conformation of the synthetic glycan hairpin. This work demonstrates that it is possible to program glycans to adopt defined conformations in aqueous solution. Overall, the bottom-up approaches used in this doctoral thesis allowed for a deeper understanding of the principles dictating carbohydrate self-assembly. The work presented here opens the way to future explorations of glycans as scaffolds for self-assembly or to perform complex functions as catalysis.Weniger anzeigen