The present study investigated the effect of a preceding, short cold treatment (4 °C, 24 h) on the resistance of Arabidopsis thaliana against hemibiotrophic Pseudomonas syringae pv. tomato (Pst) and necrotrophic Botrytis cinerea. For this aim, two different experimental cold setups were compared. In the first setup (cold pre-treatment; CT), the pathogen infection occurred directly after the cold treatment. The second experimental setup (cold priming; CP) included a memory phase between the cold treatment and the infection, whereby the impact of a priming memory on the resistance against pathogens was investigated. Arabidopsis benefited from the cold treatment and exhibited significantly increased resistance against Pst and B. cinerea. For plant defense against Pst, cold priming and cold pre-treatment led to increased resistance, while against B. cinerea only cold pretreatment resulted in transient resistance increase. To identify the immune signaling pathways responsible for the increased resistance, transcript analyses and pathogen growth experiments were conducted with Arabidopsis (Accession: Col-0) and selected mutant lines. The experiments demonstrated that cold priming-mediated resistance in Arabidopsis against virulent Pst is independent of the plant immune regulator Enhanced Disease Susceptibility 1 (EDS1) and does not alter transcript levels of pathogen-triggered Pathogenesis-related 1 (PR1), Isochorismate Synthase 1 (ICS1), FLG22-induced receptor-like Kinase 1 (FRK1), and NDR1/HIN1-like 10 (NHL10). These results, but also the observation that cold priming does not confer resistance against avirulent Pst avrRPS4 and Pst avrRPM1, indicated that cold-mediated resistance against Pst is mainly independent from effector-triggered immunity (ETI), hypersensitive response (HR), PAMPs-triggered immunity (PTI) and salicylic acid (SA) signaling. Cold pretreatment-mediated resistance against B. cinerea was also without cold signatures on the transcript levels of Pathogenesis-related 1 (PR1), Pathogenesis-related 4 (PR4), Plant Defensin 1.2a (PDF1.2a) and Phytoalexin Deficient 3 (PAD3). This suggested that cold exposure-mediated resistance against B. cinerea is independent of SA signaling, jasmonic acid (JA) signaling, and camalexin biosynthesis. Increased accumulation of reactive oxygen species (ROS) was observed in Arabidopsis leaves after the cold pre-treatment and subsequent B. cinerea infection indicating a central function of ROS in the crosstalk between the prior cold and pathogen infection. Besides other functions, ROS contribute to lignin and callose formation. Enhanced callose formation and lignification could be detected immediately after the cold exposure. In contrast, B. cinerea did not alter plant lignin amounts and pathogen-triggered callose deposition was not further affected by prior cold treatment. We extended our analyses by investigating the impact of cold-pre-treatments on the establishment of systemic aquired resistance (SAR). The induction of SAR in cold-pretreated plants was successful, but the prior cold treatments did not provide additional benefits for SAR against Pst. Interestingly, a syringe infiltration with the mock solution instead of the SAR-triggering primary Pst inoculation enhanced the susceptibility of Arabidopsis after a cold pre-treatment against Pst. The most pivotal finding of this work demonstrated that the chloroplast-localized ROS-scavenging enzymes stromal ascorbate peroxidase (sAPX) and thylakoid ascorbate peroxidase (tAPX) are essential for the wildtype-like enhanced resistance against Pst and B. cinerea after prior cold treatments. CP-mediated resistance was also confirmed in the immunocompromised null mutant enhanced disease susceptibility 1 (eds1-2) crossed with stroma ascorbate peroxidase knockout (eds1 sapx). This work, furthermore, showed that sAPX is essential for cold-induced callose formation and dispensable for pathogen-induced callose. Finally, sapx, but not thylakoid ascorbate peroxidase knockout (tapx), showed a different ROS generation pattern, with significantly more ROS being generated than in cold-treated sapx or compared to wildtype plants without cold pre-treatment. These results highlight the relevance of the chloroplast antioxidant system in cold sensing and its impact on the plant immune system.
Weniger anzeigenThis work aims to develop superhydrophobic surfaces from supramolecular xerogels with low molecular weight gelators (LMWGs). LMWGs are small organic compounds that have a strong preference to form gels in a suitable solvent. To achieve a xerogel coating, one can drop-cast the gel onto substrates such as glass cover slips, allowing it to dry under ambient condition. The LMWGs used in this work are based on a trans-1,2-diamidocyclohexane core, equipped with two equilateral perfluorinated side chains (CFn, where n represents the number of the carbon atoms on each chain). The amide groups on the core facilitate strong intermolecular hydrogen bondings and lead the way to supramolecular self-assembly, while the perfluorinated side chains contribute to the intrinsic low surface energy of the materials. Both parts are essential for the formation of the superhydrophobic xerogel coating.
The first part of this work focuses on investigating the effect of the side-chain length on the resulting xerogel coating. Eight LMWGs, from CF3 to CF10, are included in the investigation. The xerogel coatings were examined from three different scales. In the nanoscale, surface x-ray diffraction (sXRD) reveals the difference in the structural properties of the resulting supramolecular aggregates. Scanning electron microscopy (SEM) and optical microscopy were used to reveal the morphologies of the aggregates in the microscale. As for the macroscopic scale, the coatings were tested for their hydrophobicity and durability towards water flushing. In addition to the standard contact angle measurements and gravimetric studies, an image processing script coined Morphology evolution analysis (MEA) was devised to investigate the change of the coating after intensive flushing. This method evaluates the durability by assessing the change in the relative thickness of the coating through pixel intensity. The first part of this work concludes that the length of the perfluorinated side chains has a significant impact on the resulting xerogel, as certain LMWGs provide xerogel coatings with better properties in terms of both hydrophobicity and durability.
To broaden the applicability of the xerogel coating, it is crucial to overcome the intrinsic mechanical fragility of the xerogels. Therefore, the second part of this work focuses on the preparation of the more mechanically-durable hydrophobic coatings from the combination of supramolecular xerogels and polymers. CF7 was selected as the concept LMWG, while two monomers, methyl methacrylate (MMA) and trifluoroethyl methacrylate (TFEMA), were chosen as the candidates for the polymer component. Extensive screening was done to find the optimised fabrication condition for a robust hydrophobic supramolecular-polymer co-assembly. The co-assemblies were investigated with SEM and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) for the structure of the aggregates and the uniformity of the coating, respectively. The iterability and durability of the co-assemblies are again tested with water flushing. A sclerometer was employed in addition to test the scratch resistance of the co-assemblies. Practical implementations including metal corrosion protection and oil-repellency were also carried out. In conclusion, xerogel-based hydrophobic and oleophobic coatings with significantly improved scratch-resistance are achieved by fixating the supramolecular network with a polymer matrix.
Weniger anzeigenT. gondii is a zoonotic protozoon that can infect virtually all warm-blooded species on all continents. The parasite has a complex population structure, including countries and continents dominated by only a few clonal lineages, while T. gondii populations in South America are highly diverse. The genetic diversity described in Central and South America is associated with higher virulence and more severe cases of toxoplasmosis in humans, making it important to detect the introduction of such genotypes into Europe. This work focused on genotyping of T. gondii in Europe where the clonal lineage type II is predominant. The predominance of T. gondii type II in Europe was described in the past as part of global studies on population genetics of T. gondii, but there were no studies that focused exclusively on Europe. Therefore, the available genotyping information on European T. gondii was summarized in a review and the distribution of circulating strains in Europe was mapped, revealing that there was little or no information available for some countries. Moreover, it was recognized that the application of genotyping methods was not consistent between different laboratories. A frequently used genotyping method for T. gondii is based on MS markers. It represents the current reference standard for genotyping and fingerprinting. To reach consistency in T. gondii MS typing, a ring trial among five European laboratories was organized and the results were published together with guidelines for a harmonized application of MS typing. On this basis, MS typing results may become more comparable in the future, which is necessary to combine larger data sets on T. gondii genotypes originating from different studies. Guidelines for MS typing may also encourage more laboratories in Europe to use the MS method, which may help to fill the identified gaps in genotyping data. MS typing and WGS analysis revealed genetic variability within T. gondii type II. To explore this further, an NGS-based typing method with a high typing resolution among T. gondii type II strains was established. This new Ion AmpliSeq method appears to be suitable to improve the understanding of transmission pathways of T. gondii, to trace infection sources in outbreaks or to detect recombination and the introduction of genotypes to new areas. Furthermore, the harmonized MS method was applied in a study for genotyping of T. gondii DNA extracted from tissue samples of red squirrels (Sciurus vulgaris) found dead in the Netherlands. This study identified genetic clusters based on the MS typing results, but without obvious regional association. In future studies, cluster analyses can be performed with large, combined datasets using the harmonized MS typing method or Ion AmpliSeq typing to obtain further insights into the population structure of T. gondii in Europe.
Weniger anzeigenBackground: It was recently reported that periportal fibrosis in mice did affect the expression of CYP proteins, a set of pericentrally located drug-metabolizing enzymes. This observation suggests an interplay between zonated morphological disorders and metabolic zonation, a potentially clinically relevant finding. Therefore, we raised the hypothesis that periportal steatosis in mice may affect zonated drug metabolism parameters. Cross-species variation has not yet been systematically explored with respect to hepatic lobular geometry and CYP expression as needed for clinical translation. We hypothesized that lobular geometry as an anatomical feature is species-independent, whereas CYP zonal expression as a functional parameter is species-dependent. Method: We performed a detailed drug metabolism study in mice with periportal steatosis induced by feeding a high-fat methionine-choline reduced diet applied over two, respectively, four weeks. Drug metabolism was assessed in terms of the spatial distribution of drug-metabolizing CYP enzymes, CYP activity, and a pharmacokinetic study. For the cross-species analysis, we involved four species: mouse, rat, pig, and human. We developed an automated pipeline based on whole slide images (WSI) of hematoxylin-eosin-stained liver sections and immunohistochemistry to quantify lobular geometry and zonated expression of key cytochrome P450 (CYP) enzymes. Results: Periportal steatosis did not alter the pericentral expression pattern of the CYP enzymes. However, the activity of selected CYPs was related to the type and severity of steatosis. Caffeine elimination was accelerated by microvesicular steatosis, whereas midazolam elimination was delayed in macrovesicular steatosis. Using the newly developed automated image analysis pipeline, we observed that hepatic lobular geometry is rather robust, whereas zonated expression shows species-specific features, with mice being most similar to humans. Conclusion: In this thesis, we demonstrated that periportal pathology such as steatosis could affect certain features of hepatic drug metabolism, a metabolic process taking place in the pericentral region. We demonstrated the robustness of lobular geometry in four different species and described the impact of the given species on the spatial distribution of CYP proteins in normal livers. Perspective: Our planned future studies include assessing species-specific features of steatosis, including heterogeneity, and their implications for the spatial distribution of CYP expression. Based on this data, we want to perform a translational study using human samples to confirm the impact of periportal and pericentral steatosis on distinct parameters of drug metabolism.
Weniger anzeigenCancer is a leading cause of death worldwide and the second leading cause of death in Germany. The primary goal of cancer therapy is to reduce mortality and improve patient survival. However, the choice of therapy is heavily influenced by the patient’s prognosis, highlighting the importance of cancer survival prediction as a means to quantify the patient’s risk and estimate prognosis. This dissertation presents a cancer survival prediction approach that uses XGBoost tree ensemble learning and is based on gene expression data of 25 different cancer types from The Cancer Genome Atlas (TCGA). We evaluate two versions of this approach, one trained on each cancer type separately and the other trained on pan-cancer data comprising all 25 cancer types, and find that the pan-cancer approach yields improved performance over the single-cancer approach. Furthermore, we evaluate the pan-cancer approach on additional molecular data types, including mutations, copy number variations, and protein expression data, and identify gene expression as the most informative data type. To assess the biological plausibility of the gene expression-based pan-cancer survival prediction approach, we apply network propagation to gene weights derived from the survival prediction model and infer a pan-cancer survival network comprising 103 genes. These 103 genes are most significantly enriched for the tumor microenvironment, which has been associated with cancer progression, metastasis, and response to therapy, validating the biological plausibility of our survival prediction approach. Furthermore, we explore the potential of transfer learning for cancer survival prediction. To this end, we pre-train neural networks for cancer survival prediction, but also for related tasks such as tissue type and age prediction. We then transfer the learned knowledge to cancer survival prediction on independent datasets from TCGA, as well as substantially smaller cancer studies. We find that transfer learning can indeed improve cancer survival prediction, although the benefit of transfer learning may depend on the size and characteristics of the datasets used.
Weniger anzeigenCombining organic molecules with inorganic substrates, especially two-dimensional materials such as transition-metal dichalcogenides (TMDCs), is a wide field with much interest and many possibilities. Finding the right combination to achieve a purposeful union with desired properties requires a detailed examination of the fundamental processes that occur in these hybrid systems. Scanning tunnelling microscopy (STM) and spectroscopy (STS) are ideal tools for investigating these hybrid systems, as they allow us to employ their powerful capabilities of local spatial resolution on the atomic scale, resulting in direct access to the local electronic structure. The locality of electronic effects is a crucial piece of information in reaching a full understanding of the various mechanisms at play. In this thesis, we utilise STM and STS to investigate three different hybrid systems under three different aspects: In the first part, we create and explore the system of trifluoromethyl-terphenyl-thiol (CF3-3P-SH) molecules on Au(111) and MoS2/Au(111) and the various adsorption properties. We compare physisorption on both surfaces of Au(111) and MoS2/Au(111), and chemisorption, facilitated by successfully anchoring the CF3-3P-S(H) molecules to purposefully created S-vacancies in the MoS2 monolayer. The anchoring molecules are identified by their rotation around one of their terminations. We observe two different species of anchored molecules that differ only in their electronic structure: the majority shows nothing around the Fermi energy, whereas a small percentage exhibits a peak at zero bias which we assign to a Kondo resonance. This chemisorption process is disentangled at the atomic level by combining experiment and theory in collaboration. Detailed analysis of the stability of the hybrid system, ab-initio molecular dynamics simulations and DFT calculations confirm that two different molecular species are involved: intact CF3-3P-SH and dehydrogenated CF3-3P-S. Both show electronic states inside the bandgap of MoS2 which crucially differ in their occupation. Secondly, we further explore the capabilities of MoS2 as a decoupling layer that enhances the lifetime of molecular states inside its bandgap. Using the model system of single vanadyl-naphthalo-cyanine (VONc) molecules adsorbed on MoS2/Au(111), we study the electronic states of this molecule in detail. We identify the observable in-gap states and analyse the local variations in the electronic structure which are determined to be caused by the tip-perturbation potential as well as vibration-induced effects such as vibration-assisted tunnelling. In the last part, we investigate the capabilities of bulk 2H-MoTe2 as a substrate for STM, identifying and exploring its inherent n-type semiconductor characteristics and the importance of choosing suitable molecular adsorbates such as tetrathiofulvalene (TTF) molecules which show signs of charge transfer with the substrate. Various naturally occurring defects of MoTe2, showing strong states in the bandgap of MoTe2, are observed as well. These states are imaged spatially using dI/dV maps.
Weniger anzeigenNosokomiale Infektionen und die damit einhergehende Problematik der Besiedlung von Patienten mit multiresistenten Erregern (MRE) stellt immer mehr eine ernst zu nehmende Herausforderung sowohl in der Human- als auch in der Veterinärmedizin dar. Gerade in Pferdekliniken haben NI in den letzten Jahren zugenommen, weshalb ein Hygienemanagement zur Prävention von Wundinfektionen eine immer größere Bedeutung bekommt. Pferdekliniken stellen hierbei aufgrund der tierartspezifischen Anforderungen eine besondere Herausforderung dar, während Kleintierkliniken viele Erkenntnisse aus der Humanmedizin übertragen können. Besonders im Zusammenhang mit Wundinfektionen beim Pferd treten die klassischen opportunistischen und zoonotischen Pathogene wie z.B. Methicillin-resistente Staphylococcus aureus (MRSA) und Extended Spectrum Beta-Laktamase (ESBL-) produzierende Entereobacteriaceae auf. Vor diesem Hintergrund war es Ziel dieser Arbeit, ein multimodales Hygienemanagement im Zusammenhang mit SOPs zu entwickeln, welches in der Pferdeklinik eine wirksame und umsetzbare Anwendung finden kann und somit zu einer Reduzierung von Wundinfektionen beitragen soll. In dieser Studie wurde bei insgesamt 341 equinen Patienten in den Jahren 2014 und 2015 ein Eingangsscreening mittels nasaler Tupferproben und Kotproben für eine mikrobiologische Untersuchung durchgeführt und ein Status quo der mitgebrachten Keimflora ermittelt. Eingeschlossen wurden alle Patienten die mit der Indikation Kolik (n = 233) oder mit einer offenen Verletzung (n = 108) in der Klinik für Pferde, Allgemeine Chirurgie und Radiologie der Freien Universität Berlin vorstellig wurden. Zusätzlich erfolgte bei allen Verletzungen im Rahmen des Screenings eine Probennahme aus dem Zentrum der Wunde. Das Studiendesign untergliederte sich in drei verschiedene Abschnitte: Untersuchungszeitraum A im Jahr 2014, einer darauffolgenden Intervention und damit verbunden die Einführung der im Untersuchungszeitraum A entwickelten neuen Hygienemaßnahmen in Form von SOPs und anschließend Untersuchungszeitraum B im Jahr 2015. Der Fokus der SOPs für die Intervention wurde dabei auf die Verbesserung der Händehygiene-Compliance gelegt und der Verbrauch an Desinfektionsmitteln in den Untersuchungszeiträumen A und B ermittelt. Zusätzlich wurde in beiden Untersuchungszeiträumen eine aktive Surveillance von postoperativen Wundinfektionen durchgeführt und alle detektierten Infektionen einer mikrobiologischen Folgeuntersuchung unterzogen. Dadurch konnte die Infektionsrate und Belastung mit multiresistenten Erregern (MRE) in den Untersuchungszeiträumen A und B miteinander verglichen werden. Einbezogen wurden zusätzlich verschiedenen Risikofaktoren auf das Erlangen einer Wundinfektion wie die Aufenthaltsdauer, der chirurgische Eingriff und die Inzisionslänge, eine Vorbehandlung mit Antibiotika sowie Alter und Gewicht. Die Auswertungen des Eingangsscreenings zeigten, dass 3,5 % der Patienten bereits mit MRSA bei Einlieferung in die Klinik belastet waren und 10,7 % positiv auf ESBL-produzierende Enterobacteriaceae getestet wurden. Die Abstriche der Wunden zeigten eine Keimbelastung von 3,7 % mit MRSA, 1,9 % mit ESBL-produzierenden Enterobacteriaceaen und 0,9 % mit Acinetobacter baumanii (A. baumanii) bei Aufnahme in die Klinik. Im Rahmen der Studie wurden mehrere Faktoren identifiziert, die das Wundinfektionsrisiko im signifikanten Maße beeinflussten. Die Aufenthaltsdauer erhöhte sich um das Doppelte bei Patienten mit einer Wundinfektion (p = 0,001), ein chirurgischer Eingriff beeinflusste signifikant das Erlangen einer Infektion (p < 0,005) und wies damit verbunden ein 33,7-fach erhöhtes Wundinfektionsrisiko auf. Auch die stationäre Behandlung einerseits (p < 0,005) und die Vorbehandlung mit Antibiotika vor der Kliniküberweisung (p = 0,002) andererseits beeinflussten das Wundinfektionsrisiko. Zudem konnten das Alter (p = 0,006) und das Gewicht (p = 0,0037) als Risikofaktoren ermittelt werden. Insgesamt konnten 42 Infektionen in den Untersuchungszeiträumen A und B detektiert werden, wovon 69 % mit mindestens einem MRE besiedelt waren. Durch die Einführung des zielgerichteten Hygienemanagements und der dazugehörigen SOPs konnte eine deutliche Senkung von Wundinfektionen erzielt werden (p = 0,033). Bei der Indikation Kolik, von denen 48 Patienten einer Laparotomie unterzogen wurden, erlagen im Untersuchungszeitraum A 30 % der Patienten einer Wundinfektion, im Untersuchungszeitraum B nur noch 17,9 %. Bei der Indikation der Verletzungen entwickelten im Untersuchungszeitraum A 31,7 % der Patienten eine Wundinfektion und nur 25 % im Untersuchungszeitraum B. Dies entsprach einer Gesamtabnahme der Infektionsrate um 8,9 % in US B nach Intervention. Zudem sank die Gesamtzahl an MRE in den Folgeuntersuchungen der Wundinfektionen um 9,5 %. Die Haupterkenntnis aus diesen Daten war, dass zielgerichtete Maßnahmen, v.a. die Steigerung der Händehygiene-Compliance, einen großen Einfluss auf die Risikominimierung von Wundinfektionen haben mussten, der Verbrauch an Desinfektionsmitteln stieg in dieser Studie im Untersuchungszeitraum B um 190 % an.
Weniger anzeigenDie Bestimmung der aeroben mesophilen Gesamtkeimzahl auf Schlachttierkörpern eignet sich im Speziellen zur Beurteilung der Prozesshygiene am Ende der Schweineschlachtkette. Für diese mikrobiologische Schlachttierkörperuntersuchung stehen verschiedene destruktive und nicht-destruktive Techniken zur Verfügung, welche unterschiedliche Vor- und Nachteile aufweisen. Die Agarkontakt-Methode, bei der der Nähragar für eine quantitative Keimzahlbestimmung homogenisiert wird, basiert auf der Anwendung von Agarkontaktplatten. Die Probenahmetechnik mittels Agarkontaktplatten ist für die Untersuchung von Gegenständen nach DIN EN ISO 18593:2018 genormt und besitzt den entscheidenden Vorteil einer schnellen und praktikabel durchführbaren Beprobung.
Um die Aussagekraft der Ergebnisse der Agarkontakt-Methode für die Anwendung auf Schweineschlachttierkörperoberflächen bewerten zu können, wurde in einer Methodenvergleichsuntersuchung die Agarkontakt-Methode mit dem nach DIN EN ISO 17604:2015-12 genormten Nass-Trocken-Tupferverfahren in Bezug auf den Nachweis der aeroben mesophilen Gesamtkeimzahl verglichen. Dazu wurden beide Methoden in einem experimentellen Ansatz mit inokulierten Schweinehautteilstücken und in einem konventionellen Schlachtbetrieb auf Schweineschlachttierkörpern untersucht. Es ergab sich für beide Teilversuche eine statistisch signifikante Äquivalenz zwischen den beiden nicht-destruktiven Beprobungsmethoden. Der Feldversuch im Schlachtbetrieb ergab Oberflächenkeimzahlen des Schlachtkörpers, welche vereinzelt an oder unter der minimalen Nachweisgrenze für die Agarkontakt-Methode lagen. Insgesamt war die Ermittlung einer geringen Anzahl an Oberflächenkeimen mit der Agarkontakt-Methode weniger zuverlässig als mit dem Nass-Trocken-Tupferverfahren. Allerdings wurde die Vergleichbarkeit der Ergebnisse beider Methoden bei hohen Oberflächenkeimzahlen ermittelt. Insbesondere ermöglicht diese praktikable und tiergerechte Methode die mikrobiologische Untersuchung von lebenden Schlachtschweinen und Schlachttierkörpern an mehreren Schlachtprozessstufen, ohne den Arbeitsablauf unterbrechen oder die Methode wechseln zu müssen.
Die Agarkontakt-Methode realisierte eine longitudinale Studie in einem industriellen Schlachtbetrieb mit moderner Schlachttechnologie zur Bestimmung der Oberflächenkeimzahl und Salmonellen von Schlachtschweinen, beginnend im Wartestall bis zur Prozessstufe vor der Kühllagerung. Die Untersuchung ergab einen mit zahlreichen Studien vergleichbaren Verlauf der Gesamtkeimzahl über den gesamten Schlachtprozess. Zudem konnten die Berieselung im Wartestall sowie die Betäubung und Entblutung als Stufen mit einem möglichen Risiko der Kreuzkontamination identifiziert werden. Es konnte gezeigt werden, dass die Agarkontakt-Methode einen wichtigen Beitrag zur Ermittlung von systemischen und individuellen Defiziten im Schweineschlachtprozess und von kontaminierten Schlachtschweinpartien im Rahmen einer zusätzlichen betriebsspezifischen Schlachtprozessanalyse leisten kann. Die mit dieser einfachen Probenahmetechnik erhobenen Gesamtkeimzahlen und Salmonellen auf Schweinehautoberflächen können ein sinnvolles und praktikables Mittel zur ergänzenden Einschätzung und Optimierung der Schlachthygiene sein.
Weniger anzeigenThe overall objectives of this thesis were 1) to compare the effect of an additional prostaglandin F2α (PGF2α) treatment and an increased dosage of PGF2α on d 7 during an Ovsynch protocol with an untreated control group, regarding luteolysis and reproductive performance; 2) to determine the effect of progesterone (P4) supplementation by means of a P4 releasing intravaginal device (PRID) insert for 8 days during an Ovsynch protocol on pregnancy per artificial insemination (P/AI) and pregnancy loss; 3) to evaluate vaginal discharge at device removal on fertility, and 4) to evaluate the diagnostic performance of transrectal ultrasound to detect a functional corpus luteum (CL) based on circulating P4 levels.
In the first study, the aim was to compare the effect of two PGF2α treatments 24 h apart (25 mg of dinoprost at d 7 and 8) and the treatment of a double PGF2α dose (50 mg of dinoprost at d 7) with a control group (25 mg of dinoprost at d 7) during a 7-d Ovsynch protocol with inclusion of a PRID device for 8 days on luteal regression and P/AI in lactating Holstein cows. Furthermore, we wanted to evaluate the potential impact of vaginal discharge caused be the P4 insert on fertility and whether serum P4 levels correspond with ultrasound CL diagnostic.
The experiment was conducted on a single commercial farm in Northeast Germany. A total of 1,056 cows were randomly assigned within parity to receive 1 of 3 Ovsynch protocols on a weekly basis: 1) a control group in which cows received an Ovsynch protocol with a single PGF2α treatment (control: d 0, 100 μg of GnRH + PRID; d 7, 25 mg of dinoprost; d 8, PRID removal; d 9, 100 μg of GnRH), 2) an Ovsynch protocol with a double dose of PGF2α (DoubleDose: d 0, 100 μg of GnRH + PRID; d 7, 50 mg of dinoprost; d 8, PRID removal; d 9, 100 μg of GnRH) and 3) an Ovsynch protocol with an additional PGF2α treatment 24 h after the first one (2PGF: d 0, 100 μg of GnRH + PRID; d 7, 25 mg of dinoprost; d 8, 25 mg of dinoprost and PRID removal; d 9, 100 μg of GnRH). All cows received a PRID from d 0 until removal on d 8, on which vaginal discharge was evaluated and scored [vaginal score (VS) 0 = no debris, VS 1 = small flecks of purulent debris, VS 2 = abundant amount of purulent debris]. To facilitate first post partum timed AI (TAI), the farm used a Presynch-Ovsynch protocol (PGF2α, 14 d later PGF2α, 12 d later start of an Ovsynch protocol). All cows were inseminated approximately 16 h after the second GnRH treatment (G2) of the Ovsynch protocol. Ovarian ultrasonography was performed on d 0 (G1) to determine abence or presence of a CL and its size. Blood samples were collected on d 0, 7 and 9 in order to asses P4 concentrations. Pregnancy diagnosis was performed using transrectal ultrasound d 38 ± 3 after AI and reconfirmed d 80 ± 7.
Treatment affected P4 concentration at G2. Mean P4 concentrations at G2 differed (P = 0.037) among treatments (control 0.35 ± 0.02 ng/mL; DoubleDose 0.29 ± 0.02 ng/mL; 2PGF 0.30 ± 0.02 ng/mL) and were lower for 2PGF cows (P = 0.043) and DoubleDose cows (P = 0.023) compared with cows in the control group. There was an interaction between treatment and CL at G1 (P = 0.087). Cows without a CL at initiation of the protocol had decreased (P = 0.014) P4 concentrations when treated with a double dose of PGF2α and tended (P = 0.062) to have a decreased P4 concentration at G2 when receiving 2 consecutive treatments 24 h apart. Proportion of cows with luteolysis differed among treatments (P = 0.025; control 84.8%; DoubleDose 91%; 2PGF 92.6%) considering only cows with P4 concentrations above 1.0 ng/mL (indicative of presence of a CL) at first PGF2α (863/1011) and 0.5 ng/mL at G2 (indicative of complete luteolysis).
Cows that received an additional treatment 24 h apart had greater P/AI (46.5%) compared with DoubleDose cows (37.7%; P = 0.045), but did not differ compared with cows in the control group (40.3%; P = 0.144). Considering luteal status at G1, cows within the 2PGF group had greater (47.9%; P = 0.043) P/AI when compared with DoubleDose cows (32.7%), but did not differ compared with control cows (36.1%; P = 0.109) when no CL was present at protocol initiation. The overall accuracy was 87.2% to identify a functional CL using transrectal ultrasound at the beginning of the protocol. The area under the curve (AUC) was 0.901 and can be considered highly accurate. The optimum cutoff was a 20-mm diameter of the CL.
Vaginal discharge score had a significant association (P = 0.001) with P4 concentrations at the first PGF2α treatment. Cows assigned to a VS of 2 had greater (4.3 ± 0.2 ng/mL) serum P4 levels than cows assigned to score 0 (3.0 ± 0.3 ng/mL; P = 0.001) and 1 (3.7 ± 0.1 ng/mL; P = 0.002). Progesterone concentration at d 7 was greater (P = 0.027) for cows assigned to VS 1 compared with cows assigned to VS 0. Vaginal discharge score at PRID removal tended to have an association with P/AI at d 38 after AI (P = 0.072). Pregnancy per AI did not differ (P = 0.459) among cows scored with a VS of 0 and 1 [36.5% (25/69); 41.3% (320/780)], but was significantly greater [49.7% (102/207)] for cows having a VS of 2 compared with VS 1 (P = 0.039), and tended to be greater compared with VS 0 (P = 0.066).
Outcomes from this study demonstrate that both PGF2α modifications can increase luteolysis in P4 supplemented Ovsynch protocols compared with a standard PGF2α treatment on d 7 of the protocol. Interestingly, only cows receiving an additional PGF2α treatment had a numerical increase in P/AI (6.2 %), especially in cows without a CL at G1 (11.8 %), whereas an increased dose of PGF2α did not lead to any improvement in reproductive performance. Vaginal discharge at d 8 of the protocol, after PRID removal, was associated with higher P4 concentrations at d 7 and greater P/AI. Ultrasound can be deemed as a valuable tool for CL detection.
The second study aimed to elucidate the effect of P4 supplemention for 8 days, by means of a PRID insert, during an Ovsynch protocol on P/AI and pregnancy loss compared with a standard 7-d Ovsynch protocol.
A total of 716 lactating Holstein cows from one commercial dairy farm in Northeast Germany were enrolled in this study. The treatment group was part of the aforementioned study and received an 8-d P4-based Ovsynch protocol (PRIDsynch: d 0, 100 μg of GnRH + PRID; d 7, 25 mg of dinoprost; d 8, PRID removal; d 9, 100 μg of GnRH), whereas the control group received a standard 7-d Ovsynch protocol as part of the farms reproductive schedule (control: d 0, 100 μg of GnRH; d 7, 500 μg of cloprostenol; d 9, 100 μg of GnRH). All cows were inseminated approximately 16 h after G2. Pregnancy diagnosis was performed by transrectal ultrasound examination d 38 ± 3 after AI and reconfirmed d 80 ± 7. Pregnancy loss included cows that experienced pregnancy loss from d 38 to 80.
Results from this study demonstrate the overall beneficial effect of an elongated P4, 8 d supplementation with a PRID insert in an Ovsynch protocol on reproductive performance. Pregnancy per AI was significantly increased in PRIDsynch cows [P = 0.014; 38.9 % (115/360)] compared with untreated control cows [31.7 % (115/360)] on d 38 ± 3 after AI. However, pregnancy loss was not affected by treatment [P = 0.279; control: 8.8 (10/113) vs. PRIDsynch: 6.2 (9/146)].
Overall, this thesis shows that 1) the proportion of cows with complete luteal regression near TAI was increased by both PGF2α modifications, but only the second treatment 24 h apart resulted in greater P/AI compared with the increased PGF2α dose and a numerical increase in P/AI compared with control cows, especially in cows lacking a CL at protocol initiation, 2) the addition of a PRID from d 0 until removal on d 8 of the TAI protocol increased reproductive performance but did not influence pregnancy loss, 3) vaginal discharge caused by P4 inserts has no negative impact on fertility and 4) ovarian ultrasound examinations are suitable for detection of a functional CL. Taken together, these results have a potential to improve reproductive performance on dairy farms using TAI protocols.
Weniger anzeigenFleisch von Pferden und anderen Equiden wird seit Tausenden von Jahren konsumiert und ist aus ernährungsphysiologischer Sicht ein wertvolles Nahrungsmittel. Die Produktion von Pferdefleisch bietet zudem gegenüber der Produktion von Rindfleisch ökologische Vorteile durch die Reduktion der Methanemission und ökonomische durch gute Gewichtszunahme und Schlachtausbeute. Trotzdem ist Fleisch von Equiden in Europa, insbesondere in Deutschland, ein Nischenprodukt. Gleichzeitig sind die Vorschriften hinsichtlich der Anwendung und Dokumentation von Arzneimitteln bei Schlachtequiden sehr umfangreich. Zum einen gelten für sie dieselben Vorschriften wie für andere Lebensmittel liefernde Tiere, zum anderen gibt es spezifische Vorschriften, die nur für Equiden gelten. Eine dieser Sondervorschriften ist die Positivliste für Equiden. In der Positivliste sind Medikamente aufgeführt, die nicht in der Tabelle 1 der VO (EU) Nr. 37/2010 aufgeführt sind und daher nicht zur Anwendung bei anderen Lebensmittel liefernden Tieren zugelassen sind. Die Nachweisraten an chemischen und pharmakologischen Rückständen in Fleisch- und Organproben von Pferden, die im Rahmen des Nationalen Rückstandskontrollplans (NRKP) getestet wurden, sind im Vergleich zu Proben anderer Fleisch liefernder Tiere, sehr hoch.
Vor diesem Hintergrund sollte im Rahmen der vorliegenden Dissertation überprüft werden, ob der Kenntnisstand der Pferde behandelnden Tierärzteschaft, von Equidenbesitzer*innen und Equidenhalter*innen in Deutschland bezüglich der geltenden gesetzlichen Regelungen zu Arzneimittelanwendung und -dokumentation und Equidenschlachtstatus ausreichend ist und ob die Dokumentation von angewendeten Arzneimitteln in der Praxis bei Equiden korrekt und vollständig durchgeführt wird. Daher wurden vier Online-Umfragen zwischen 29. Oktober und 15. Dezember 2021durchgeführt und letztlich die Daten von 153 in Praxen arbeitenden Tierärzt*innen, neun Pferde-Klinik-Tierärzt*innen, 170 Equidenbesitzer*innen und 70 Equidenhalter*innen in die Untersuchungen einbezogen. Des Weiteren wurden zwischen 01. Juni und 31. Dezember 2021 Daten zur Arzneimitteldokumentation in 195 Equidenpässen dokumentiert und ausgewertet. In einer ersten Studie wurden zum einen die Antworten der 153 Tierärzt*innen, der 170 Equidenbesitzer*innen und 70 Equidenhalter*innen miteinander verglichen. In einer zweiten Studie wurden die Antworten von 116 Tierärzt*innen, die selbst Equiden kastrieren, mit den Antworten der neun Klinik-Tierärzt*innen und Daten von 195 Equidenpässen verglichen. Die Ergebnisse der ersten Studie zeigen große Wissenslücken aller drei Teilnehmergruppen sowohl hinsichtlich der geltenden Vorschriften für Arzneimittelanwendung und -Dokumentation als auch bezüglich des Schlachtstatus. Insgesamt empfanden 68,4 % (91/133) der Tierärzt*innen die Vorgaben der Positivliste als „eher kompliziert“ bis „kompliziert“. Insgesamt konnten 38,4 % (58/151) der Tierärzt*innen das korrekte Vorgehen nicht beschreiben, wenn Phenylbutazon an einen Schlachtequiden verabreicht wird. Die Anwendung von Phenylbutazon bei Lebensmittel liefernden Tieren ist verboten (VO (EU) Nr. 37/2010). Gleichzeitig nannten 56,2 % (86/153) Phenylbutazon als das oder eines der am häufigsten durch sie angewendeten NSAIDs. Wann es sich bei einem Equiden rechtlich um einen Schlachtequiden handelt, konnten 41,4 % (70/170) der Equidenbesitzer*innen und 42,9 % (30/70) der Equidenhalter*innen nicht korrekt beantworten. Von den Equidenhalter*innen gaben 34,4 % (24/70) an, keine oder nur schlechte Kenntnis über die geltenden Vorschriften bezüglich Arzneimitteldokumentation bei Equiden zu haben. Die Ergebnisse der zweiten Studie zeigen, dass angewendete Arzneimittel häufig nicht im Equidenpass dokumentiert werden. Insgesamt gehörten 24,1 % (47/195) der untersuchten Equidenpässe zu Schlachtequiden. Medikamentenkombinationen, die mindestens ein Medikament der Positivliste enthalten, wurden von 86,7 % (91/105) der Tierärzt*innen zur Anästhesie benutzt, die Pferdehengste abgelegt kastrieren und von 64,3 % (36/56) derer, die Eselhengste abgelegt kastrieren. Während der Kastration am stehend Tier wurden Medikament der Positivliste von 29,6 % (8/27) der Tierärzt*innen bei Pferdehengsten und 30,8 % (4/13) der Tierärzt*innen bei Eselhengsten zur Anästhesie verwendet. Insgesamt kastrierten 90,5 % (105/116) der Tierärzt*innen nach eigenen Angaben teilweise, oder ausschließlich nach der Methode am abgelegten Equiden. Es wurde jedoch nur in 4,0 % (1/25) der Equidenpässe von Schlachtequidenwallachen eine Dokumentation über verabreichte Anästhetika der Positivliste vorgefunden. Insgesamt war in nur 4,6 % (9/195) aller Equidenpässe die Dokumentation über verabreichte Medikamente vorhanden.
Zusammenfassend zeigen die Ergebnisse, dass der Wissensstand von Tierärzt*innen, Equidenhalter*innen und Equidenbesitzer*innen bezüglich des Schlachtstatus‘ und der Arzneimittelanwendung und -dokumentation bei Schlachtequiden unzureichend ist. Gleichzeitig wird die Dokumentation von Medikamenten in Equidenpässen häufig nur unvollständig oder gar nicht durchgeführt. Dies kann in Arzneimittelrückständen im Fleisch von Equiden resultieren und stellt daher einen Risikofaktor für die Sicherheit von Equidenfleischkonsument*innen dar.
Weniger anzeigenThis thesis reveals the metabolic responses to intestinal nematode infections in highperforming chickens and delineates the development of an effective non-invasive diagnostic tool for the detailed characterisation of infections with significant implications for broader impacts on poultry Management
High-performing chickens of the Lohmann Brown genotype were experimentally infected with both Ascaridia galli and Heterakis gallinarum, which also led to concurrent histomonosis nfections. The birds were necropsied at specific time points after infections, and the liver and plasma were investigated for the metabolic responses to the infections. Notably, this is the first study providing a detailed, time-dependent analysis of the infection-induced metabolic alteration in nematode infected chickens. The identification of key metabolites associated with different infection stages including larval penetration of the mucosa, patency, and reinfection provides a nuanced understanding of the dynamic host-parasite interplay, paving the way for targeted investigations into specific pathways and their functional consequences. This finding prompts a deeper investigation into the trade-offs between immune defence and Overall performance, with implications for breeding programs and management strategies aimed at optimizing both health and productivity in poultry.
The elevated concentrations of amino acids during heightened immune responses at early phase of nematode infection indicated the possible diversion of metabolic resources towards immune response at the expense of performance and productivity. The increased Plasma amino acids were attributed to a potential imbalance in protein secretion and re-absorption in the small intestine. The study further identified altered metabolic pathways, including Arginine proline metabolism which are crucial for collagen synthesis and tissue repair, thus highlighting the importance of amino acids in supporting the defence mechanism during nematode infection. Additionally, the identification of key metabolites like trimethylamine Noxide (TMAO) whose high concentration may indicate the presence of mixed nematode infections, opens up a new perspective for biomarker research. Further exploration into the applicability of TMAO indiverse parasitic situations are encouraged particularly the mechanism of TMAO production and its role in discriminating the status of helminth infections in chicken.
The status of nematodes infection is currently achieved through faecal egg counts which may not always be reliable due to variations in worm fecundity amongst other reasons. An alternative method is to measure anti-ascarid antibodies in chicken plasma. However, this practice may not always meet current welfare standards in poultry production, as it involves an invasive technique for blood collection that also requires licensed experts to perform. Therefore, this thesis further developed a new non-invasive nematode diagnosis based on the measure of worm antigens in chicken faeces.
The development of this coproantigen ELISA as a non-invasive diagnostic tool presents an opportunity for improved parasite management. This novel approach accurately differentiated infected and non-infected chickens for both nematode species, offering a promising noninvasive alternative to faecal egg counts. While showing high diagnostic accuracy for A. galli, further refinement is needed for accuracy and sensitivity to H. gallinarum. Temporal variations among different diagnostic methods highlighted the need for tool-specific selection. The coproantigen ELISA demonstrated superior performance in overall qualitative diagnostics, surpassing other methods. Concurrently, the antibody ELISA showcased an early detection capability, while faecal egg counting emerged as the method most closely correlated with worm burdens, serving as a reliable measure of infection intensity.
In the broader context of existing information, this study advances our understanding of the potential metabolic cost of defence against nematode infections in high-performing chickens. The identified metabolites and pathways not only contribute to the fundamental knowledge of host-parasite interactions but also lay the groundwork for targeted interventions to mitigate the impact of these infections on poultry productivity. The development of innovative noninvasive diagnostic tool adds an applied dimension to the research, providing tangible benefits for poultry producers grappling with the challenges of nematode infections.
Weniger anzeigenAutomated content moderation in a modern sense starts taking many forms: moderating social media, debates, therapy diaries and student learning processes such as essay writing. To tackle these tasks one can apply different AI techniques, such as classifications, information retrieval, chatbots, symbolic logical reasoners, and sometimes all of the above, combining them into so-called hybrid AI systems. Combining and running multiple AI components with different characteristics in a connected manner, or employing one model to elucidate another, emerges as a viable alternative to end-to-end systems. This is primarily because of their manageable and transparent nature, offering a potential improvement over end-to-end systems. Additionally, they may provide a more accurate representation of the various elements found in human cognition, blending resilient learning with rapid pattern recognition alongside reasoning facilitated by logical operations. In this thesis, two instances of hybrid AI systems are developed in combination with two content moderation use cases. “Check News in One Click” is a web application designed for streamlined news verification. It incorporates a fusion of statistical linguistic, transformer-based, and rule-based components that I developed and integrated into a productive system with a user-friendly interface. Specifically, this application specializes in verifying content from both conventional news sources and social media news channels, with a focus on identifying manipulative language and the presence of pro-Kremlin propaganda, which became a major problem in light of the Russian invasion of Ukraine. PapagAI is an online platform for higher education students, where I created, combined and implemented an AI module for automated moderation of reflective essays using supervised models, a clustering, a linguistic processing module and a heuristic determiner which mines a prompt database for appropriate questions and amelioration suggestions. Through this application, my objective was to address the German educational system’s requirement for improving teacher trainee retention rates at universities and easing the workload of tutors by streamlining the feedback process. In addition to the user tests, to evaluate the developed systems, here I also discuss questions related to the Ethics of AI, the European Union legal framework regarding automated content moderation, as well as the interpretability and sustainability of deep learning models.
Weniger anzeigenSchüler*innen mit den unterschiedlichsten individuellen Voraussetzungen und Bedarfen haben seit der Ratifizierung der UN-Behindertenrechtskonvention 2009 Anspruch auf den Besuch einer allgemeinen Schule und damit auf das gemeinsame Lernen mit Gleichaltrigen ohne entsprechende Ansprüche und Bedarfe. Bislang bestehende Bestrebungen, Klassen bzw. Lerngruppen insbesondere während der Sekundarstufe nach bestimmten Merkmalen ihrer Schüler*innen, wie ihres Alters und ihrer Leistungen, zu homogenisieren, werden durch diesen Anspruch weitgehend aufgebrochen, was Inklusion zu einer grundlegenden Reform des Bildungssystems macht. Dies hat zur Folge, dass in einer inklusiven Lernumgebung Schüler*innen mit den unterschiedlichsten Fähigkeiten und Förderbedarfen aufeinandertreffen und sozial interagieren. Aus sozialisationstheoretischer Perspektive ermöglicht dies sowohl für diejenigen mit entsprechenden Förderbedarfen (im Folgenden mit SPF für „sonderpädagogische Förderbedarfe“ abgekürzt) als auch für ihre Mitschüler*innen ohne SPF spezielle Lern- und Entwicklungsmöglichkeiten. Gerade wie es Schüler*innen ohne SPF in inklusiven Lernsettings ergeht und welche Erfahrungen sie durch den schulischen Kontakt mit Gleichaltrigen mit SPF machen, findet in der bisherigen Forschung noch wenig Beachtung. So fällt auch der aktuelle Diskurs um diese Gruppe heterogen aus. Einerseits wird von positiven Erfahrungen ausgegangen, indem Schüler*innen ohne SPF durch den Kontakt zu Gleichaltrigen mit SPF für Diversität und Heterogenität sensibilisiert werden und individuell davon profitieren können. Andererseits wird dagegen argumentiert, dass Schüler*innen ohne SPF als sozial unerwünscht angesehene negative Verhaltensweisen ihrer Peers mit SPF für sich übernehmen könnten, dass Lehrkräfte zu vielen Anforderungen im inklusiven Unterricht gegenüberstünden und sich vermehrt um diejenigen mit SPF kümmern müssten, was letztlich in negativen Beziehungserfahrungen und im Abfallen der akademischen Leistungen von Schüler*innen ohne SPF resultieren könnte. Diesem Diskurs widmet sich die vorliegende Dissertation und nimmt in drei Einzelbeiträgen verschiedene Outcomes auf Ebene der Schüler*innen ohne SPF, die in einem inklusiven Setting lernen, in den Blick. In einem ersten Beitrag wird entsprechend betrachtet, ob zwischen Schüler*innen mit und ohne SPF negative Peereffekte bestehen, die dazu beitragen, dass Schüler*innen ohne SPF in inklusiven Lernsettings das vermeintlich ungünstigere soziale Verhalten ihrer Mitschüler*innen mit SPF für sich übernehmen und letztlich geringeres soziales Verhalten zeigen als Gleichaltrige in nicht-inklusiven Settings. Den angestellten Mehrebenenanalysen zufolge unterscheiden sich Schüler*innen der sechsten Jahrgangsstufe nicht in ihrem sozialen Verhalten aufgrund des Besuchs einer inklusiven Lernumgebung generell und auch nicht in Abhängigkeit davon, wie viele Schüler*innen mit SPF mit ihnen gemeinsam unterrichtet werden. Allerdings fällt ihr soziales Verhalten geringer aus, je mehr Gleichaltrige aus niedrigen sozialen Schichten mit ihnen lernen. Die verwendeten Daten belegen zudem, dass die sozioökonomische Klassenkomposition in inklusiven Klassen insgesamt geringer ausfällt als in Parallelklassen ohne Schüler*innen mit SPF. Der zweite Beitrag fokussiert die emotionalen Belange von Schüler*innen ohne SPF und geht der Frage nach, ob Vergleichsprozesse zwischen Schüler*innen mit und ohne SPF in inklusiven Klassen dazu beitragen, dass inklusiv lernende Schüler*innen ohne SPF ein höheres Selbstwertgefühl ausbilden als ihre Peers in nicht-inklusiven Klassen. Auch hier liefern Mehrebenenanalysen von Daten von Schüler*innen ohne SPF der fünften Jahrgangsstufe keine Hinweise darauf, dass der inklusive Lernkontext generell sowie die Klassenzusammensetzung aus Schüler*innen mit und ohne SPF mit ihrem Selbstwertgefühl assoziiert ist. Stattdessen wird erneut deutlich, dass die sozioökonomische Klassenkomposition für unterschiedliche Ausprägungen des Selbstwertgefühls sorgt und, dass in inklusiven Klassen ebendiese insgesamt geringer ausfällt. Schließlich wird in einem dritten Beitrag die Beziehung zwischen Lehrkräften und Schüler*innen aus Sicht von Schüler*innen ohne SPF in den Blick genommen. Theoretisch ist davon auszugehen, dass das Verhalten und Lernen von Schüler*innen mit SPF nicht den normativen Erwartungen ihrer Lehrkräfte entsprechen und dadurch Schüler*innen ohne SPF eine größere Zuwendung erfahren. In der aktuellen Forschungslandschaft zeigt sich diese Annahme allerdings bislang nicht. Daher wurde erneut mehrebenenanalytisch geprüft, ob Schüler*innen ohne SPF in inklusiven Klassen der sechsten Jahrgangsstufe die Beziehung zu ihren Lehrkräften als weniger positiv als Gleichaltrige in nicht-inklusiven Klassen bewerten. Aus den Befunden lassen sich weder Vor- noch Nachteile eines inklusiven Lernsettings für die Beziehung zwischen Schüler*innen ohne SPF und ihren Lehrkräften ableiten. Auch die verschiedenen Förderbedarfe der Schüler*innen mit SPF bedingen die Beziehung nicht negativ. Die Ergebnisse bereichern den aktuellen Diskurs um Folgen eines inklusiven Schulsystems für Schüler*innen ohne SPF insofern, dass sie negative Annahmen hinsichtlich ihres sozialen Verhaltens und ihres emotionalen Befindens entkräften. Wenn das inklusive Setting in den angestellten Untersuchungen auch keine positiven Wirkungen auf soziale und emotionale Outcomes der Schüler*innen ohne SPF hat, sind auch keine Nachteile erkennbar. Stattdessen zeigt sich, dass inklusive Klassen, wie sie in den vorliegenden Arbeiten operationalisiert werden, überwiegend von Schüler*innen aus sozial schwächeren Familien besucht werden und eine geringe sozioökonomische Klassenkomposition durchaus negativ mit dem sozialen Verhalten und emotionalen Befinden von Schüler*innen ohne SPF zusammenhängt. So lässt sich von den Ergebnissen ableiten, dass Schüler*innen mit SPF häufig in Klassen platziert werden, in denen ohnehin schon vermehrt Schüler*innen mit besonderen Anforderungen und Bedarfen aufgrund ihrer sozialen Herkunft lernen. Bei der Strukturierung von Klassen bzw. Lerngruppen und der Verteilung von Schüler*innen mit SPF auf einzelne Jahrgänge sollte also die gesamte Heterogenität aller Schüler*innen berücksichtigt werden, insbesondere ihr sozioökonomischer Status, um etwaige negative Effekte hinsichtlich sozialer und emotionaler Outcomes von Schüler*innen ohne SPF – und ggf. auch derjenigen mit SPF – zu vermeiden.
Weniger anzeigenDiese Dissertation untersucht unter Anwendung soziologischer Machttheorien Prozesse der Zuschreibung, Konstruktion und Dekonstruktion von Autorität des Wissens in medizinischen Erzählungen der späten chinesischen Kaiserzeit. Als vergleichende Studie zeigt sie Ähnlichkeiten und Differenzen in den Definitionen guter medizinischer Tätigkeit, die von Akteuren vor dem Hintergrund fluider sozialer und epistemischer Grenzen im Feld der Medizin vorgetragen wurden. Am Fallbeispiel chinesischer Heiler, die in unterschiedlichen, auch nicht-elitären Kontexten um Legitimation für sich selbst oder ihre bevorzugten Behandlungsformen kämpfen mussten, leistet sie einen Beitrag zur besseren Kenntnis über die Funktionsweisen von wissensbezogenen Machtfigurationen im Bereich der Medizin Chinas. Als Quellen dienen Fallgeschichten des relativ unbekannten Gelehrtenarztes Xiao Jing 蕭京 (1605-1672) und des Verletzungs-Spezialisten Hu Tingguang 胡廷光 (18.-19. Jh.), sowie Erzählungen aus der Rezeptsammlung des Wander-arztes Wang Wenmo 王文謨 (sp. 16. Jh.) und zweier Handschriften anonymer Wanderheiler der späten Qing-Zeit (1644-1911). An ihnen zeigt sich, wie zusätzlich zu fachspezifischem Wissen ökonomisches, soziales, kulturelles und symbolisches Kapital über das Medium der Sprache in Texte transportiert und in andere Kapitalsorten umgewandelt wurde, um medizinisches Denken und Handeln zu autorisieren. So unterschiedliche Akteure wie ein Gelehrtenarzt aus dem siebzehnten Jahrhundert und mittellose Wanderheiler des neunzehnten Jahrhunderts griffen dabei auf die relativ gleichbleibenden Werte und Normen der Gesamtgesellschaft zurück, um ihre therapeutische Praxis zu legitimieren und Autorität des Wissens zu konstruieren. Die feinen Unterschiede in der Art, wie die Autoren die Güte medizinischen Wirkens bemaßen, und welche Formen von Autorität sich in ihren unterschiedlich textualisierten Erzählungen auf welche Weise konstruieren ließen, hing von den zur Verfügung stehenden Mitteln und dem damit zusammenhängenden (sprachlichen) Habitus der Akteure ab. Unterschiede zeigen sich in der Arzt-Patienten-Interaktion, der Interpretation von Fachterminologie, in Vorstellungen von Wirksamkeit und Definitionen von Virtuosität. Sie manifestieren sich auch im Umgang mit wundersamen Phänomenen, in der Betonung des Sichtbaren oder Unsichtbaren vor dem Hintergrund unterschiedlicher Kosmografien und Körperbilder, sowie in der Bewertung von praktischem und theoretischem Wissen. Die in den Erzählungen identifizierten Differenzen werden im breiteren Diskurs über das Verhältnis von Praxis und Theorie in der Wissenschaftsgeschichte Chinas verortet, der auch als Wettbewerb über die primäre Ressource „Wissen“ angesehen werden kann. Das Narrativ der chinesischen Literaten-Elite in Frage stellend, dass das Durchdringen universeller Prinzipen praktischen Kenntnissen überlegen sei, war es gerade dieses praktische Wissen, das den Ausübenden besondere Sachautorität durch erfolgreiche Lösungen unmittelbarer Probleme verlieh. So kann es als nicht unerheblicher Faktor angesehen werden, der zu Veränderungen von Machtfigurationen in sozialen Feldern des Expertentums beitrug.
Weniger anzeigenLa presente es una investigación en la que me sumerjo a navegar el proceso de representación del río Atrato (en el departamento del Chocó, Colombia) a cargo del Cuerpo Colegiado de Guardianes del Atrato (CCGA) en el contexto de la Sentencia T-622 de 2016 de la Corte Constitucional. Esta Sentencia reconoce al río Atrato como un sujeto de derechos y es una respuesta jurídica a las denuncias de las organizaciones ribereñas ante la crisis socioambiental en la cuenca. La crisis ha sido marcada por actividades de minería de oro con mercurio y cianuro, deforestación, disputas por el control territorial y por el control de las rutas del narcotráfico (por parte de los grupos armados), además de por la negligencia estatal. El CCGA se erige como una figura ejemplar, siendo este el primer caso dentro del marco de los derechos de la naturaleza. Aquí, las organizaciones ribereñas articulan la representación de un cuerpo de agua de manera interétnica y plurivocal. La investigación abarca el período de 2019 a 2022, dialogando con eventos pasados y futuros que influyen en la configuración del CCGA. La pregunta de investigación se centró en quiénes son los guardianes del río, cómo llevan a cabo la representación del río, dónde circulan sus voces, cómo escuchar al Atrato a través del CCGA, cuál es el contenido de su vocería, sus estrategias y desafíos y, en definitiva, cómo están incidiendo en que otros futuros sean posibles. Esta investigación se realizó desde la etnografía multimodal y multilocal, fuertemente afectada por la pandemia de Covid-19. Para hacerle seguimiento a las vocerías del CCGA, participé en diversos espacios de vocería tanto en el territorio como en plataformas digitales. El enfoque teórico se centró en la antropología política y de medios, basándome en la ontología política y relacional. He propuesto el concepto de vocear ríos como herramienta analítica para navegar el proceso de representación del Atrato. Hago énfasis en el verbo activo de vocear, relacionado a cómo se configuran y articulan de manera multimodal las vocerías interétnicas a partir de las relaciones con los cuerpos de agua, siguiendo el lema del CCGA ‘Atrato es, Atrato soy, Atrato somos y debemos seguir siendo’. En otras palabras, el estudio parte de las continuidades relacionales y temporales de los ríos con los que las vocerías constantemente devienen.
Weniger anzeigenIn eukaryotes, the transcription cycle, which includes initiation, elongation, and termination, is regulated at multiple steps by both cis-regulatory elements and trans-acting factors. At protein-coding genes, successful transcription initiation is often followed by a pivotal regulatory step, i.e. the promoter-proximal pause. During this pause, the elongation complex is supplemented by additional elongation factors enabling productive elongation, proper termination and co-transcriptional RNA processing. In addition to this scheduled regulated pause, Pol II encounters obstacles such as nucleosomes, pause predisposing cis- sequences or other physical barriers that cause Pol II to move backward - a phenomenon referred to as Pol II backtracking. In case of a transient pause, when Pol II backtracks by one nucleotide, it can cleave the backtracked nucleotide itself, as it has an intrinsic nuclease property. However, when more extensive backtracking is thermodynamically favorable, Pol II is trapped in an immobilized state known as transcriptional arrest and requires an auxiliary factor TFIIS (TCEA in human cells). TFIIS alleviates transcriptional arrest by enhancing the RNA cleavage activity of Pol II. Following the hydrolysis of backtracked RNA, a new 3’ is generated and the active site of Pol II is free to resume RNA synthesis. The molecular mechanism of TFIIS has been extensively characterized both structurally and biochemically; however, our understanding of its role in human cells remains incomplete because of the additional complexity incurred by four highly conserved TFIIS paralogs. To date, there have been no multiomics studies investigating paralog-specific roles. In our research project, we analyzed the function of two paralogs expressed in HEK293T cells: the ubiquitously expressed TCEA1 and lowly expressed cerebellum- and testis- specific TCEA2. We employed two cellular systems: an inducible epitope-tagged protein expression system to determine their individual interaction partners and genomic binding patterns and CRISPR- knockouts of each and both proteins to evaluate the impact on elongation at the level of nascent and messenger RNA. Our results demonstrate that both paralogs bind Pol II shortly after initiation and, in their absence, Pol II occupancy is strikingly increased at the promoter-proximal region of the majority of active genes, as revealed by High-sensitive native elongating transcript sequencing (HiS-NET-seq). About a half of those genes have reduced Pol II occupancy in the gene body. This indicates that backtracking is a common event at the promoter-proximal region and TCEA1 and TCEA2 are needed to progress into the gene body and, possibly, also for proper Pol II processivity. Unexpectedly, TCEA2 deletion was more detrimental to cellular growth than the TCEA1 knockout. The TCEA2 and the double knockout cells had a profound delay in DNA replication accompanied by activated DNA damage response. The deletion of TCEA2 had a more pronounced impact on the transcriptional output, indicating that, despite its higher expression level, TCEA1 alone is not sufficient to alleviate backtracking. This suggests that TCEA2 is a potent elongation factor and has its own target genes that regulate cell proliferation.
Weniger anzeigenThis work aims to develop novel systems for the transport of active pharmaceutical ingredient (API) especially small molecules to specific target in biological entities by tackling the main three challenges that this domain faces. The challenges of solubilizing hydrophobic drugs, the elimination of drugs from the blood stream and specific targeting to a defined site. The system is based on biodegradable polyglycerol copolymers by integrating biodegradable moieties into the polyglycerol backbone via the copolymerization of the glycidol monomer with 7-membered lactone rings containing an ester functional group or an ester and disulfide bond functional group, and a linear diacid that contains a disulfide bond. In the first two projects where the comonomer chosen was caprolactone, two host molecules were encapsulated in the DDS, sunitinib for cancer therapy and tofacitinib for skin inflammation therapy. The structure of the project can be divided into the following packages: (i) bulk straightforward-synthesis of the copolymer, (ii) chemical and physical characterization, (iii) encapsulation and release of the chosen API (iv) in vitro biological assays, and (v) in vivo or ex vivo tests. In both cases the system was proven to increase the solubilization of the guest drug significantly and improve its performance in comparison to the drug alone. The introduction of the sulfate end groups into the system led to its accumulation into the specific site in vivo. In the first project, the copolymers were synthesized on a large scale (20 g) through a simple two-step process. In vivo fluorescence imaging revealed significant accumulation of the DDS in tumor environments. Sunitinib, an anticancer drug, was loaded into the DDS, and its toxicity was assessed both in vitro and in vivo. Results showed similar toxicities between the drug encapsulated in dPGS-PCL and the free drug in A431 and HT-29 cells, with comparable cellular uptake. In the second project, the chosen API was tofacitinib. Inflammatory skin disorders, such as psoriasis and alopecia areata, stem from dysregulation in the innate immune system, triggering the Janus kinase-signal transducer and activator of transcription (JAK-STAT) inflammatory pathway by cytokines like interleukin 6 (IL-6). JAK inhibitors, notably tofacitinib, disrupt this pathway by binding to JAK enzymes. However, topical applications of these inhibitors show limited efficacy, particularly for alopecia areata. This study introduces a novel carrier, sulfated dendritic polyglycerol with caprolactone segments (dPGS-PCL), to improve tofacitinib delivery. Testing on ex-vivo human skin models demonstrates enhanced skin penetration of tofacitinib when loaded into dPGS-PCL compared to free tofacitinib. Anti-inflammatory efficacy was evaluated through IL-6 and IL-8 release, and STAT3 and STAT5 activation assays in inflamed skin models, indicating reduced activation of inflammatory markers with increased tofacitinib penetration. The second system and third project, glycidol was copolymerized with the comonomer containing an ester and a disulfide bond, were investigated thoroughly in terms of structure and physical characteristics. The purpose was to understand the effect of the disulfide bond, whether on the initial stages like synthesis or later stages like the chemical and physical characteristics of the copolymer. Its copolymerization with glycidol was compared to the copolymerization of caprolactone with glycidol under the same conditions via two different copolymerization mechanisms. Interestingly, the structure obtained when using the comonomer containing the disulfide bond was unique: an ideal random copolymer. This was not the case when the comonomer used was caprolactone. Moreover, three different copolymers of the same molecular weight with different disulfide ratios were tested for degradation and behavior in aqueous solution. The project also focused on the biocompatibility of the copolymer for future employment in biological entities. Third system and fourth project, glycidol was copolymerized with a diacid that contains a disulfide bond in a simple manner, without another catalyst or solvent. The diacid acted as the proton donor to initiate the polymerization and was integrated in the polyglycerol backbone. Redox-degradable hydrogels loaded with an antibacterial peptide (vancomycin) were formed using the reducible polyglycerol as a building block, cross-linked by 4-arm polyethylene glycol-thiol (4-arm PEG-SH). The hydrogel degrades under reductive conditions triggered by glutathione, leading to the controlled release of the antibacterial peptide. Rheological analysis was conducted to assess the mechanical properties, including stiffness, softness, and self-healing capability, for various ratios and concentrations of both components. Hydrogel degradation was confirmed through rheological measurements and weight loss analysis. FITC-albumin and vancomycin were successfully loaded into the hydrogel, and the release kinetics were evaluated for both sustained and on-demand release profiles. Furthermore, in vitro, and in vivo experiments demonstrated that the vancomycin-loaded hydrogel acts as an effective antibacterial barrier for wound dressing and accelerates the healing of infectious wounds in a mouse model. In conclusion, the design of straightforward, scalable, and solvent free drug delivery systems is crucial for an adequate translation of the system from research to application stage. However, the knowledge around the system should be complete and the performance should be maximized. Moving forward from the first system into the second, and third the expectation of the improvement of the system is suggested by introducing a second degradable moiety that will in retrospect enhance the drug release. Therefore, the future steps should focus on the encapsulation of a guest molecule and its release and testing the disulfide containing system in vivo, to be able to compare the performance to the caprolactone containing system, keeping in mind that challenges might also arise along the way due to the sensitive nature of the disulfide bond.
Weniger anzeigenThe significant relevance of air pollution increased in our society in recent years due to its adverse health effects on animals and humans. This is caused by the increasing amount of pollutants worldwide. These pollutants also have an effect on the skin as it comes into contact every day. It is important to address all the possible aspects of danger to prevent such damage. In addition, pollutants such as cigarette smoke can lead to premature skin ageing, damage to the skin barrier, pigmentation disorders, and cell damage which is caused by free radicals. These factors can worsen symptoms for patients with existing skin conditions, like atopic dermatitis and acne. Air pollution can also cause new conditions to develop. The extent of damage on the skin caused by cigarette smoke is not yet clear, and it remains uncertain how to protect the skin from it. As a result, skincare products claiming an "anti-pollution effect" have been released to the markets in recent years. Currently, there are no proper methods to produce meaningful results for measuring the effect of pollution on the skin. It is important to assess the level of risk cigarette smoke poses to the skin or the effectiveness of applied substances in providing protection. For risk management, an unambiguous determination was necessary and hence it was deemed essential to establish cigarette smoke exposure method. For this purpose, two specially designed exposure chambers were constructed to expose ex vivo and in vivo skin tissue to cigarettes smoke. The concentration of smoke in the chamber was determined initially by a commercial particle measuring device, which was capable of measuring particles ranging from concentration 0.001 to a maximum of 400 mg/m³. It was found that the smoke from one cigarette exceeded the quantifiable levels measured with the particle measuring device in the chamber. A method was created to establish a correlation between the particle concentration and the nicotine concentration within the chamber that could come into contact with the skin. Nicotine acted as a surrogate parameter for cigarette smoke in this work. A consistent smoking regime was established for subsequent measurement of the impact of skin exposure. To quantify the nicotine content on the skin, a filter paper was positioned next to each skin sample. The sample was extracted with ethanol and the absorbance of nicotine was measured at a wavelength of 262 nm, using a UV-Vis spectrometer. A calibration curve was generated with pure substance nicotine. The results reveal a statistically significant positive correlation between the measured nicotine concentration and the particle concentration in the chamber. Once a reproducible method for exposing the skin to cigarette smoke had been established, two new techniques have been devised for measuring the impact of cigarette smoke on the skin. Prior investigations have demonstrated that the generation of free radicals leads to oxidative stress and is the main mechanism of skin damage caused by air pollution. Free radicals can be measured via electron spin resonance (EPR) spectroscopy. The study evaluated the impact of cigarette smoke on excised porcine skin with different spin probes. Prior research has proven that cigarette smoke can induce free radicals in the skin. There is a dose dependency between the measured nicotine concentration and the radical production in the skin. The combination of UVA and cigarette smoke leads to an increase in radical formation due to synergistic effects. Furthermore, the impact resulting from induced oxidative stress in the excised porcine skin was gauged via heightened autofluorescence utilizing the confocal Raman microscope (CRM). The autofluorescence technique was effectively transferred to in vivo studies. Results revealed that the measured autofluorescence was higher in test subject post-exposure to cigarette smoke than pre-exposure. Notwithstanding, the method is restricted to skin types I-III as high levels of melanin in the skin can disturb the measurements. The specific mechanisms underlying the observed increase in autofluorescence have yet to be determined. Nevertheless, it has been verified that oxidative stress, rather than cigarette smoke components, is accountable for the increase in autofluorescence. Both methods were used to evaluate the efficacy of different formulations containing of antioxidants and chelating agents. Notably, the formulation incorporating epigallocatechin-3-gallate (EGCG), a key ingredient found in green tea (Camellia Sinensis), exhibited the optimal performance in both methods. While both methods seem similar, the EPR method is somewhat limited. Specifically, for this test procedure, it is important that the tested agent does not react with the spin probe. The efficacy of antioxidants in the formulations should be optimally measured. For instance, chelating agents are based on a distinct active principle that cannot be optimally measured through the EPR method. In contrast, the CRM method can efficiently measure all active ingredient groups without the need for additional markers. It is also a promising method to apply in vivo. No additional UVA irradiation is necessary either, making the CRM method the superior approach for measuring the effectiveness of anti-pollution products.
Weniger anzeigenIn Deutschland ist die Kernenergie eine Technologie, die starke emotionale Reaktionen hervorruft. Die Argumente für und gegen ihre Nutzung reichen von der emissionsarmen und kontinuierlichen Energieerzeugung bis zu den lokalen Auswirkungen des Uranabbaus, gesundheitlichen Risiken und ungelösten technischen Herausforderungen. Trotz des Ausstiegs aus der kommerziellen Kernenergie im April 2023 bleibt v.a. eine drängende Frage: die sichere Entsorgung hochradioaktiver Reststoffe. Nach dem Standortauswahlgesetz in Deutschland muss die Lagerung für eine Million Jahre sicher sein. Dieser immense Zeitraum wird die Lebensspanne von Menschen umfassen, die diese Reststoffe nicht erzeugt haben, aber potenziell mit den Auswirkungen der Entsorgung leben müssen. Daher stellt sich die Frage, ob in Bezug auf hochradioaktive Reststoffe überhaupt von gerechtem Handeln gesprochen werden kann. Um dieser Frage näherzukommen, wurde in dieser Arbeit eine umfassende Literaturrecherche zu den theoretischen Grundlagen, zeitgenössischen Theorien und Dimensionen der Gerechtigkeit durchgeführt. Die meisten Forschungsarbeiten konzentrieren sich auf universelle Gerechtigkeitstheorien, die für alle Menschen und zu allen Zeiten gelten sollen. Um neue Erkenntnisse zu gewinnen, wurde der Ansatz der ‚Existenzweisen‘ von Bruno Latour verwendet, der eine bislang ungenutzte und individuelle Perspektive eröffnet, die von den bisherigen Paradigmen der Gerechtigkeitsforschung abweicht. Zur empirischen Fundierung wurden zwei quantitative Erhebungen durchgeführt: Erstens eine Grundlagenstudie, um allgemeine Aspekte des Gerechtigkeitsempfinden zu untersuchen, und zweitens eine Vertiefungsstudie, bei der die wahrgenommene Gerechtigkeit von nuklearer Entsorgung anhand konkreter, fiktiver Vignetten untersucht wurde.
Weniger anzeigenFluorine’s outstanding capability to influence physico-chemical properties of organic molecules make fluorine substitution an attractive strategy to modulate the binding affinities in protein-ligand and protein-protein systems. The direction and magnitude with which fluorine influences the binding affinity is often difficult to predict, as multiple effects may play a role. Computational methods and Molecular Dynamics (MD) simu- lations in particular are an excellent tool to study such effects, as they allow for atomic precision and in-depth insights into the multiple components of the binding affinity. I have compiled selected aspects of using computational methods to study fluorination in protein systems in a perspective article, which is part of this thesis. Furthermore, I use MD simulations to study how fluorine impacts the binding properties of selected protein- protein or protein-amino acid systems. The first system is the complex of trypsin with fluorinated variants of Abu-BPTI. In Abu-BPTI, the crucial amino acid Lys15 is replaced by the shorter aliphatic amino acid Abu, which comes with a loss of inhibitor strength. Some of the inhibitor strength can be restored by fluorination. An MD based study of the water molecules in the binding pocket of these protein complexes revealed a highly dynamic water network, with strongly interconnected water molecules. The fluorinated moiety of Abu does not interact with the water molecules, making it unlikely that the in- hibitor activity is restored via water mediated bonds between trypsin and fluorine. The analysis of the unbinding paths using Random Acceleration MD (RAMD) revealed a novel metastable state for all of the studied variants, which we call the pre-bound state. This state is clearly distinct from the fully bound state in position and orientation and is stable in long MD simulations. Moreover, the states differ in their interaction pattern, with fluorine possibly having a stabilizing effect on the formation of the pre-bound state. The second system studied here is the protein PTP1B in complex with a phosphoty- rosine mimetic with a highly fluorinated headgroup. I characterized the binding pose and fluorine specific interactions between the mimetic and the protein binding pocket residues. The third system is the GrsA A domain in complex with fluorinated pheny- lalanine variants. Here, I characterized the interruption of an aromatic interaction by fluorination. With respect to the impact of fluorination on the interaction of proteins, the results of this thesis show no evidence for direct water mediated interactions between proteins and fluorine, but indicate that fluorine might influence pre-bound intermedi- ates. For future research it might be interesting to investigate the effects on other components of binding affinities, such as binding entropy. Furthermore, not only the impact of fluorination on fully bound states should be investigated, but also the impact on possible pre-bound states.
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