TY - JOUR A1 - Arnholdt, Jörg A1 - Kamawal, Yama A1 - Holzapfel, Boris Michael A1 - Ripp, Axel A1 - Rudert, Maximilian A1 - Steinert, Andre Friedrich T1 - Evaluation of implant fit and frontal plane alignment after bi-compartmental knee arthroplasty using patient-specific instruments and implants JF - Archives of Medical Science N2 - Introduction The goals of successful bi-compartmental knee arthroplasty are to achieve correct fit and positioning of the implant, while appropriately correcting the mechanical alignment of the leg after surgery. As these requirements are not always reliably fulfilled using off-the-shelf implant systems, newer approaches for bi-compartmental resurfacing have been explored. Material and methods In this article we report the radiographic results of 30 patients with anteromedial osteoarthritis (OA) who were treated with a novel patient-specific fixed-bearing bi-compartmental knee resurfacing system using custom-made implants and instruments. Utilizing standardized pre- and postoperative radiographic analyses (based on anterior-posterior and lateral, anterior-posterior weight-bearing full-length radiographs, patella skyline views and preoperative computed tomography (CT) scanning) implant fit and positioning as well as correction of the mechanical axis (hip-knee-ankle angle, HKA) were determined. Results On average, HKA was corrected from 173.4 ±3.47° preoperatively to 179.4 ±2.85° postoperatively. The coronal femoro-tibial angle was corrected on average 5.61°. The preoperative tibial slope measured on lateral views was 6.38 ±2.4°, while the average slope in the CT-based planning protocol (iView) was 6.14 ±2.40°. Postoperative lateral tibial slope was determined to be 5.77 ±1.97°. The thickness of the posterior femoral cuts was measured intraoperatively and, in all cases, corresponded well to the targeted thickness of the cuts provided by the iView. The joint line was preserved in all cases and the average Insall-Salvati index was 1.078 ±0.11 pre- and 1.072 ±0.11 postoperatively. The fit of the implant components measured by over- or underhang was excellent throughout (< 1.01 mm). Conclusions Custom-made bicompartmental knee arthroplasty can ensure optimized fitting and positioning of the implant with restoration of the leg axis. These implants could be considered as an alternative primary solution for knee surgeons treating bi-compartmental disease. KW - implant fit KW - bi-compartmental knee arthoplasty KW - bi-compartmental KW - implant positioning KW - knee osteoarthritis KW - knee arthroplasty KW - patient-specific KW - knee alignment Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159668 VL - 14 IS - 6 ER - TY - JOUR A1 - Langenhorst, Daniela A1 - Tabares, Paula A1 - Gulde, Tobias A1 - Becklund, Bryan R. A1 - Berr, Susanne A1 - Surh, Charles D. A1 - Beyersdorf, Niklas A1 - Hünig, Thomas T1 - Self-recognition sensitizes mouse and human regulatory T cells to low-dose CD28 superagonist stimulation JF - Frontiers in Immunology N2 - In rodents, low doses of CD28-specific superagonistic monoclonal antibodies (CD28 superagonists, CD28SA) selectively activate regulatory T cells (Treg). This observation has recently been extended to humans, suggesting an option for the treatment of autoimmune and inflammatory diseases. However, a mechanistic explanation for this phenomenon is still lacking. Given that CD28SA amplify T cell receptor (TCR) signals, we tested the hypothesis that the weak tonic TCR signals received by conventional CD4\(^{+}\) T cells (Tconv) in the absence of cognate antigen require more CD28 signaling input for full activation than the stronger TCR signals received by self-reactive Treg. We report that in vitro, the response of mouse Treg and Tconv to CD28SA strongly depends on MHC class II expression by antigen-presenting cells. To separate the effect of tonic TCR signals from self-peptide recognition, we compared the response of wild-type Treg and Tconv to low and high CD28SA doses upon transfer into wild-type or H-2M knockout mice, which lack a self-peptide repertoire. We found that the superior response of Treg to low CD28SA doses was lost in the absence of self-peptide presentation. We also tested if potentially pathogenic autoreactive Tconv would benefit from self-recognition-induced sensitivity to CD28SA stimulation by transferring TCR transgenic OVA-specific Tconv into OVA-expressing mice and found that low-dose CD28SA application inhibited, rather than supported, their expansion, presumably due to the massive concomitant activation of Treg. Finally, we report that also in the in vitro response of human peripheral blood mononuclear cells to CD28SA, HLA II blockade interferes with the expansion of Treg by low-dose CD28SA stimulation. These results provide a rational basis for the further development of low-dose CD28SA therapy for the improvement of Treg activity. KW - D665 KW - regulatory T cells KW - self-reactivity KW - autoimmunity KW - CD28 superagonists KW - TGN1412 KW - TAB08 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159387 VL - 8 IS - 1985 ER - TY - JOUR A1 - Reichmuth, Anne A1 - Henning, Lea A1 - Pinnel, Nicole A1 - Bachmann, Martin A1 - Rogge, Derek T1 - Early detection of vitality changes of multi-temporal Norway spruce laboratory needle measurements—the ring-barking experiment JF - Remote Sensing N2 - The focus of this analysis is on the early detection of forest health changes, specifically that of Norway spruce (Picea abies L. Karst.). In this analysis, we planned to examine the time (degree of early detection), spectral wavelengths and appropriate method for detecting vitality changes. To accomplish this, a ring-barking experiment with seven subsequent laboratory needle measurements was carried out in 2013 and 2014 in an area in southeastern Germany near Altötting. The experiment was also accompanied by visual crown condition assessment. In total, 140 spruce trees in groups of five were ring-barked with the same number of control trees in groups of five that were selected as reference trees in order to compare their development. The laboratory measurements were analysed regarding the separability of ring-barked and control samples using spectral reflectance, vegetation indices and derivative analysis. Subsequently, a random forest classifier for determining important spectral wavelength regions was applied. Results from the methods are consistent and showed a high importance of the visible (VIS) spectral region, very low importance of the near-infrared (NIR) and minor importance of the shortwave infrared (SWIR) spectral region. Using spectral reflectance data as well as indices, the earliest separation time was found to be 292 days after ring-barking. The derivative analysis showed that a significant separation was observed 152 days after ring-barking for six spectral features spread through VIS and SWIR. A significant separation was detected using a random forest classifier 292 days after ring-barking with 58% separability. The visual crown condition assessment was analysed regarding obvious changes of vitality and the first indication was observed 302 days after ring-barking as bark beetle infestation and yellowing of foliage in the ring-barked trees only. This experiment shows that an early detection, compared with visual crown assessment, is possible using the proposed methods for this specific data set. This study will contribute to ongoing research for early detection of vitality changes that will support foresters and decision makers. KW - laboratory measurements KW - derivatives KW - spectroscopy KW - forest health KW - ring-barking KW - random forest KW - index analysis Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159253 VL - 10 IS - 1 ER - TY - JOUR A1 - Mall, David A1 - Larsen, Ashley E. A1 - Martin, Emily A. T1 - Investigating the (mis)match between natural pest control knowledge and the intensity of pesticide use JF - Insects N2 - Transforming modern agriculture towards both higher yields and greater sustainability is critical for preserving biodiversity in an increasingly populous and variable world. However, the intensity of agricultural practices varies strongly between crop systems. Given limited research capacity, it is crucial to focus efforts to increase sustainability in the crop systems that need it most. In this study, we investigate the match (or mismatch) between the intensity of pesticide use and the availability of knowledge on the ecosystem service of natural pest control across various crop systems. Using a systematic literature search on pest control and publicly available pesticide data, we find that pest control literature is not more abundant in crops where insecticide input per hectare is highest. Instead, pest control literature is most abundant, with the highest number of studies published, in crops with comparatively low insecticide input per hectare but with high world harvested area. These results suggest that a major increase of interest in agroecological research towards crops with high insecticide input, particularly cotton and horticultural crops such as citrus and high value-added vegetables, would help meet knowledge needs for a timely ecointensification of agriculture. KW - ecological intensification KW - insecticides KW - agroecology KW - agricultural intensity KW - biological pest control KW - crop KW - study system Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158977 VL - 9 IS - 1 ER - TY - THES A1 - Schott, Sebastian T1 - Identification of trihalide photodissociation patterns by global vibrational wavepacket analysis of broadband magic-angle transient absorption data T1 - Identifikation von Trihalidphotodissoziationsmustern mittels globaler Vibrationswellenpaketanalyse von breitbandigen, unter magischem Winkel gemessenen, transienten Absorptionsdaten N2 - The invention of laser pulse shapers allowed for various quantum control experiments, where a chemical reaction is guided by specifically tailored laser pulses. However, despite of the prominent role of the liquid phase in chemistry, no successful attempt for controlling the selectivity of a bond-fission reaction has yet been reported in this state of matter. Promising candidates for such an experiment are C$_{\infty\mathrm{v}}$-symmetric trihalide anions with two different chemical bonds like $\ce{I2Cl-}$, because these molecules notionally offer the most simplest selectivity-control scenario of breaking either the one or the other bond and they are expected to dissociate under ultraviolet (UV) irradiation like it is known for the most-studied trihalide $\ce{I3-}$. In order to investigate in this thesis the possibility that the dissociation reaction of such trihalides branches into two different photofragments, the ultrafast photodissociation dynamics of $\ce{I3-}$, $\ce{Br3-}$, $\ce{IBr2-}$ and $\ce{ICl2-}$ (point group D$_{\infty\mathrm{h}}$) as well as of $\ce{I2Br-}$ and $\ce{I2Cl-}$ (point group C$_{\infty\mathrm{v}}$) in dichloromethane solution were measured with broadband transient absorption spectroscopy in magic-angle configuration. The identification of the reaction pathway(s) relies on vibrational wavepacket oscillations, which survive the dissociation process and therefore carry not only informations about the reactant trihalides but also about the fragment dihalides. These characteristic vibrational wavenumbers were extracted from the measured transient absorption spectra by globally fitting the population dynamics together with the wavepacket dynamics. Until recently, such a combined model function was not available in the well-established fitting tool Glotaran. This made it inevitable to develop a custom implementation of the underlying variable-projection fitting algorithm, for which the computer-algebra software Mathematica was chosen. Mathematica's sophisticated built-in functions allow not only for a high flexibility in constructing arbitrary model functions, but also offer the possibility to automatically calculate the derivative(s) of a model function. This allows the fitting procedure to use the exact Jacobian matrix instead of approximating it with the finite difference method. Against the expectation, only one of the two thinkable photodissociation channels was found for each of the investigated C$_{\infty\mathrm{v}}$ trihalides. Since the photofragments recombine, their absorption signal as well as the reactant ground state bleach recover. This happens in a biexponential manner, which in the case of $\ce{I3-}$ was interpreted by Ruhman and coworkers with the direct formation of a neutral dihalogen fragment $\ce{I2}$ beside the negatively charged dihalide fragment $\ce{I2-}$. In this thesis, such a direct reaction channel was not found and instead the fast component of the biexponential decay is explained with vibrational excess energy mediating the recombination-preceding electron transfer process $\ce{I2- + I -> I2 + I-}$, while the slow component is attributed to cooled-down fragments. In addition to the trihalide experiments, the possibility of a magic-angle configuration for polarization-shaping control experiments was theoretically investigated in this thesis by deriving magic-angle conditions for the third-order electric-dipole response signal of arbitrarily polarized laser pulses. Furthermore, the subtleties of anisotropy signals violating the well-known range of \numrange{-0.2}{0.4} were studied. N2 - Die Erfindung von Laserpulsformern ermöglichte eine Vielzahl von Quantenkontrollexperimenten, bei denen eine chemische Reaktionen mittels maßgeschneiderten Laserpulsen gelenkt wird. Allerdings wurde trotz der bedeutenden Rolle der flüssigen Phase in der Chemie bis heute kein erfolgreicher Versuch publiziert in diesem Aggregatszustand die Selektivität bei der Spaltung chemischer Bindungen zu kontrollieren. Vielversprechende Kandidaten für ein derartiges Experiment sind C$_{\infty\mathrm{v}}$-symmetrische Trihalidanionen mit zwei verschiedenen chemischen Bindungen, wie z.B. $\ce{I2Cl-}$, da diese Moleküle prinzipiell das einfachste Kontrollszenario, in dem entweder die eine oder die andere Bindung gespalten wird, ermöglichen und, wie vom meist untersuchten Trihalid $\ce{I3-}$ bekannt, eine Dissoziationsreaktion unter ultravioletter (UV) Bestrahlung erwartet wird. Um im Rahmen dieser Arbeit zu untersuchen, ob sich die Dissoziationsreaktion solcher Trihalide in zwei verschiedene Photofragmente aufzweigt, wurde die ultraschnelle Photodissoziationdynamik von $\ce{I3-}$, $\ce{Br3-}$, $\ce{IBr2-}$ und $\ce{ICl2-}$ (Punktgruppe D$_{\infty\mathrm{h}}$) sowie von $\ce{I2Br-}$ und $\ce{I2Cl-}$ (Punktgruppe C$_{\infty\mathrm{v}}$) in Dichlormethanlösung mittels breitbandiger transienter Absorptionsspektroskopie in der Magischer-Winkel-Konfiguration gemessen. Die Identifikation der Reaktionspfade stützt sich auf die Oszillation von Schwingungswellenpaketen, die den Dissoziationsprozess überstehen und folglich nicht nur Informationen über die Trihalidedukte sondern auch über die Dihalidprodukte tragen. Diese charakteristischen Schwingungswellenzahlen wurden aus jedem gemessenen transienten Absorptionsspektrum durch einen globalen Fit der Populationsdynamik zusammen mit der Wellenpaketdynamik extrahiert. Bis vor Kurzem war solch eine kombinierte Modellfunktion in dem gängigen Fitwerkzeug Glotaran nicht verfügbar. Dies machte es erforderlich eine eigene Implementation des zugrunde liegenden Fitalgorithmus der variablen Projektionen zu entwickeln, wofür die Computeralgebrasoftware Mathematica gewählt wurde. Mathematicas Funktionsumfang erlaubt nicht nur eine große Flexibilität bei der Konstruktion beliebiger Modellfunktionen, sondern bietet auch die Möglichkeit, die Ableitungen einer Modellfunktion automatisch zu berechnen. Dies erlaubt der Fitprozedur die exakte Jacobi-Matrix zu verwenden, anstatt diese mittels der Finite-Differenzen-Methode zu approximieren. Wider den Erwartungen wurde für jedes der untersuchten C$_{\infty\mathrm{v}}$ Trihalide nur einer der zwei denkbaren Photodissoziationskanäle beobachtet. Da die Photofragmente rekombinieren, klingen deren Absorptionssignal und das Grundzustandsausbleichen des Edukts wieder ab. Dies passiert stets in biexponentieller Form, was im Fall von $\ce{I3-}$ von Ruhman und Kollegen mit der direkten Bildung von neutralen Dihalogenfragmenten $\ce{I2}$ neben den negativ geladenen Dihalidfragmenten $\ce{I2-}$ interpretiert wurde. Im Rahmen dieser Arbeit ließ sich ein solcher direkter Reaktionskanal nicht beobachten. Stattdessen wird die schnelle Komponente des biexponentiellen Zerfalls mit überschüssiger Vibrationsenergie erklärt, die den der Rekombination vorrangehenden Elektrontransferprozess $\ce{I2- + I -> I2 + I-}$ begünstigt, während die langsame Komponente abgekühlten Fragmenten zugeordnet wird. Zusätzlich zu den Tihalidexperimenten wurde durch Herleitung Magischer-Winkel-Bedingungen für Antwortsignale aus elektrischer Dipolwechselwirkung dritter Ordnung mit beliebig polarisierten Laserpulsen theoretisch untersucht, ob eine Magischer-Winkel-Konfiguration für Polarisationsformungs-Kontrollexperimente möglich ist. Weiterhing wurden die Feinheiten anisotroper Signale, die den gut bekannten Bereich von \numrange[range-phrase=~bis~]{-0.2}{0.4} verletzten, untersucht. KW - Femtosekundenspektroskopie KW - Pump-Probe-Technik KW - Ultrakurzzeitspektroskopie KW - Ultraschnelle Photochemie KW - ultrafast photochemistry Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159677 ER - TY - JOUR A1 - Togninalli, Matteo A1 - Seren, Ümit A1 - Meng, Dazhe A1 - Fitz, Joffrey A1 - Nordborg, Magnus A1 - Weigel, Detlef A1 - Borgwardt, Karsten A1 - Korte, Arthur A1 - Grimm, Dominik G. T1 - The AraGWAS Catalog: a curated and standardized Arabidopsis thaliana GWAS catalog JF - Nucleic Acids Research N2 - The abundance of high-quality genotype and phenotype data for the model organism Arabidopsis thaliana enables scientists to study the genetic architecture of many complex traits at an unprecedented level of detail using genome-wide association studies (GWAS). GWAS have been a great success in A. thaliana and many SNP-trait associations have been published. With the AraGWAS Catalog (https://aragwas.1001genomes.org) we provide a publicly available, manually curated and standardized GWAS catalog for all publicly available phenotypes from the central A. thaliana phenotype repository, AraPheno. All GWAS have been recomputed on the latest imputed genotype release of the 1001 Genomes Consortium using a standardized GWAS pipeline to ensure comparability between results. The catalog includes currently 167 phenotypes and more than 222 000 SNP-trait associations with P < 10\(^{-4}\), of which 3887 are significantly associated using permutation-based thresholds. The AraGWAS Catalog can be accessed via a modern web-interface and provides various features to easily access, download and visualize the results and summary statistics across GWAS. KW - model organism KW - genotype KW - phenotype Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158727 VL - 46 IS - D1 ER - TY - THES A1 - Hampe, Irene Aurelia Ida T1 - Analysis of the mechanism and the regulation of histatin 5 resistance in \(Candida\) \(albicans\) T1 - Analyse des Mechanismus und der Regulierung von Histatin 5 Resistenz in \(Candida\) \(albicans\) N2 - Antimycotics such as fluconazole are frequently used to treat C. albicans infections of the oral mucosa. Prolonged treatment of the fungal infection with fluconazole pose a risk to resistance development. C. albicans can adapt to these stressful environmental changes by regulation of gene expression or by producing genetically altered variants that arise in the population. Adapted variants frequently carry activating mutations in zinc cluster transcription factors, which cause the upregulation of their target genes, including genes encoding efflux pumps that confer drug resistance. MDR1, regulated by the zinc cluster transcription factor Mrr1, as well as CDR1 and CDR2, regulated by the zinc cluster transcription factor Tac1, are well-known examples of genes encoding efflux pumps that extrude the antimycotic fluconazole from the fungal cell and thus contribute to the survival of the fungus. In this study, it was investigated if C. albicans can develop resistance to the antimicrobial peptide histatin 5, which serves as the first line of defence in the oral cavity of the human host. Recently, it was shown that C. albicans transports histatin 5 outside of the Candia cell via the efflux pump Flu1. As efflux pumps are often regulated by zinc cluster transcription factors, the Flu1 efflux pump could also be regulated by a zinc cluster transcription factor which could in a hyperactive form upregulate the expression of the efflux pump, resulting in increased export of histatin 5 and consequently in histatin 5 resistance. In order to find a zinc cluster transcription factor that upregulates FLU1 expression, a comprehensive library of C. albicans strains containing artificially activated forms of zinc cluster transcription factors was screened for suitable candidates. The screening was conducted on medium containing mycophenolic acid because mycophenolic acid is also a substrate of Flu1 and a strain expressing a hyperactive zinc cluster transcription factor that upregulates FLU1 expression should exhibit an easily recognisable mycophenolic acid-resistant phenotype. Further, FACS analysis, quantitative real-time RT-PCR analysis, broth microdilution assays as well as histatin 5 assays were conducted to analyse the mechanism and the regulation of histatin 5 resistance. Several zinc cluster transcription factors caused mycophenolic acid resistance and upregulated FLU1 expression. Of those, only hyperactive Mrr1 was able to confer increased histatin 5 resistance. Finding Mrr1 to confer histatin 5 resistance was highly interesting as fluconazole-resistant strains with naturally occurring Mrr1 gain of function mutations exist, which were isolated from HIV-infected patients with oral candidiasis. These Mrr1 gain of function mutations as well as artificially activated Mrr1 cause fluconazole resistance by upregulation of the efflux pump MDR1 and other target genes. In the course of the study, it was found that expression of different naturally occurring MRR1 gain-of-function mutations in the SC5314 wild type background caused increased FLU1 expression and increased histatin 5 resistance. The same was true for fluconazole-resistant clinical isolates with Mrr1 gain of function mutations, which also caused the overexpression of FLU1. Those cells were less efficiently killed by histatin 5 dependent on Mrr1. Surprisingly, FLU1 contributed only little to histatin 5 resistance, rather, overexpression of MDR1 mainly contributed to the Mrr1-mediated histatin 5 resistance, but also additional Mrr1-target genes were involved. These target genes are yet to be uncovered. Moreover, if a link between the yet unknown Mrr1-target genes contributing to fluconazole resistance and increased histatin 5 resistance can be drawn remains to be discovered upon finding of the responsible target genes. Collectively, this study contributes to the understanding of the impact of prolonged antifungal exposure on the interaction between host and fungus. Drug therapy can give rise to resistance evolution resulting in strains that have not only developed resistance to fluconazole but also to an innate host mechanism, which allows adaption to the host niche even in the absence of the drug. N2 - Antimykotika wie Fluconazol werden häufig zur Behandlung von C. albicans Infektionen der Mundschleimhaut verwendet. Dabei stellt eine langzeitige Behandlung der Pilzinfektion mit Fluconazol ein Risiko zur Resistenzentwicklung dar. C. albicans kann sich an solche Umweltveränderungen anpassen, indem es die Genexpression reguliert oder genetisch veränderte Varianten produziert, welche in der Population entstehen. Adaptierte Varianten tragen häufig aktivierende Mutationen in Zink-Cluster-Transkriptionsfaktoren, welche die Hochregulierung der Expression von Genen verursachen, darunter solche, die für Multidrug-Effluxpumpen kodieren und dadurch Antimykotikaresistenz verleihen können. MDR1, reguliert durch den Zink-Cluster-Transkriptionsfaktor Mrr1, sowie CDR1 und CDR2, reguliert durch den Zink-Cluster-Transkriptionsfaktor Tac1, sind bekannte Beispiele für Effluxpumpen, die das Antimykotikum Fluconazol aus der Pilzzelle extrudieren und somit zum Überleben der Pilzzelle beitragen. In dieser Arbeit wurde untersucht, ob C. albicans eine Resistenz gegen das antimikrobielle Peptid Histatin 5 entwickeln kann, das in der Mundhöhle des menschlichen Wirtes als erste Verteidigungsbarriere gegen den Pilz dient. Kürzlich wurde gezeigt, dass C. albicans Histatin 5 über die Effluxpumpe Flu1 aus der Candia-Zelle heraustransportiert (Li et al., 2013). Da Effluxpumpen häufig durch Zink-Cluster-Transkriptionsfaktoren reguliert werden, könnte auch die Flu1-Effluxpumpe durch solch einen Transkriptionsfaktor reguliert werden, der in einer hyperaktiven Form die Expression der Effluxpumpe hochregulieren könnte, was wiederrum zu einem erhöhten Export von Histatin 5 und folglich zur Histatin 5 Resistenz führen könnte. Um einen Zink-Cluster-Transkriptionsfaktor zu finden, der die FLU1-Expression hochreguliert, wurde mit Hilfe einer Bibliothek von C. albicans-Stämmen, die künstlich aktivierte Formen von Zink-Cluster-Transkriptionsfaktoren enthält, nach geeigneten Kandidaten gesucht. Das Screening wurde auf Mycophenolsäure-haltigem Medium durchgeführt, da Mycophenolsäure ebenfalls ein Substrat von Flu1 ist. Folglich sollte ein Stamm mit hyperaktivem Zink-Cluster-Transkriptionsfaktor, welcher die FLU1-Expression hochreguliert, einen leicht erkennbaren Mycophenolsäure-resistenten Phänotyp aufweisen. Weiterhin wurden FACS-Analysen, quantitative real-time RT-PCR-Analysen, Broth microdilution-Assays sowie Histatin 5-Assays durchgeführt, um den Mechanismus und die Regulierung der Histatin-5-Resistenz zu analysieren. Mehrere Zink-Cluster-Transkriptionsfaktoren verursachten Mycophenolsäure-Resistenz und erhöhten die FLU1-Expression. Von diesen war nur hyperaktives Mrr1 in der Lage, eine erhöhte Histatin-5-Resistenz zu verleihen. Das Auffinden von Mrr1 als Regulator der Histatin 5-Resistenz war hochinteressant, da fluconazolresistente Stämme mit natürlich vorkommenden MRR1 gain-of-function Mutationen existieren, die aus HIV-infizierten Patienten mit oropharyngealer Candidiasis isoliert wurden. Diese gain-of-function Mutationen sowie künstlich aktivierendes Mrr1 verursachen Fluconazol-Resistenz durch Hochregulation der Effluxpumpe MDR1 und anderer Zielgene. Im Verlauf der Studie wurde herausgefunden, dass verschiedene natürlich vorkommende MRR1 gain-of-function Mutationen im SC5314 Wildtyp Hintergrund eine erhöhte FLU1-Expression und eine erhöhte Histatin-5-Resistenz verursachten. Das Gleiche galt für Fluconazol-resistente klinische Isolate mit Mrr1 gain-of-function Mutationen, welche die Überexpression von FLU1 verursachten. Zellen dieser Isolate wurden, abhängig von Mrr1, weniger wirksam durch Histatin 5 abgetötet. Überraschenderweise trug FLU1 nur wenig zur Histatin-5-Resistenz bei, vielmehr trug die Überexpression von MDR1 hauptsächlich zur Mrr1-vermittelten Histatin-5-Resistenz bei, aber auch weitere Mrr1-Zielgene waren daran beteiligt. Diese Mrr1-Zielgene gilt es nun noch zu entdecken. Ob ein Zusammenhang zwischen diesen noch unbekannten Mrr1-Zielgenen hergestellt werden kann, die zur Fluconazolresistenz sowie zu einer erhöhten Histatin-5-Resistenz beitragen, wird erst nach dem Auffinden der verantwortlichen Zielgene geprüft werden können. Zusammenfassend trägt diese Studie zum Verständnis der Auswirkungen einer anhaltenden antimykotischen Exposition auf die Interaktion zwischen Wirt und Pilz bei. Eine medikamentöse Therapie kann zu einer Resistenzentwicklung führen, aus der Stämme hervorgehen, welche nicht nur eine Resistenz gegen Fluconazol entwickelt haben, sondern gleichzeitig eine Resistenz gegen einen angeborenen Wirtsabwehrmechanismus, der eine Adaption an die Wirtsnische auch in Abwesenheit des Antimykotikums ermöglicht. KW - Histatin 5 KW - Candida albicans KW - Efflux pump KW - MDR1 KW - MRR1 KW - Mrr1 KW - MDR1 KW - Fluconazole KW - Efflux pump Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159634 ER - TY - JOUR A1 - Lauth, Hans-Joachim A1 - Schlenkrich, Oliver T1 - Making Trade-Offs Visible: Theoretical and Methodological Considerations about the Relationship between Dimensions and Institutions of Democracy and Empirical Findings JF - Politics and Governance N2 - Whereas the measurement of the quality of democracy focused on the rough differentiation of democracies and autocracies in the beginning (e.g. Vanhanen, Polity, Freedom House), the focal point of newer instruments is the assessment of the quality of established democracies. In this context, tensions resp. trade-offs between dimensions of democracy are discussed as well (e.g. Democracy Barometer, Varieties of Democracy). However, these approaches lack a systematic discussion of trade-offs and they are not able to show trade-offs empirically. We address this research desideratum in a three-step process: Firstly, we propose a new conceptual approach, which distinguishes between two different modes of relationships between dimensions: mutual reinforcing effects and a give-and-take relationship (trade-offs) between dimensions. By introducing our measurement tool, Democracy Matrix, we finally locate mutually reinforcing effects as well as trade-offs. Secondly, we provide a new methodological approach to measure trade-offs. While one measuring strategy captures the mutual reinforcing effects, the other strategy employs indicators, which serve to gauge trade-offs. Thirdly, we demonstrate empirical findings of our measurement drawing on the Varieties of Democracy dataset. Incorporating trade-offs into the measurement enables us to identify various profiles of democracy (libertarian, egalitarian and control-focused democracy) via the quality of its dimensions. KW - control-focused democracy KW - democracy KW - egalitarian democracy KW - libertarian democracy KW - Varieties of Democracy KW - Democracy Matrix KW - measurement of democracy KW - profile of democracy KW - quality of democracy KW - trade-off Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159588 VL - 6 IS - 1 ER - TY - THES A1 - Hebron Mwalwisi, Yonah T1 - Assessment of Counterfeit and Substandard Antimalarial Medicines using High Performance Thin Layer Chromatography and High Performance Liquid Chromatography T1 - Untersuchung der Qualität gefälschter Antimalaria-Medikamente mittels Hochleistungs-Dünnschichtchromatographie und Hochleistungs-Flüssigchromatographie N2 - Although the prevalence of substandard and counterfeit pharmaceutical products is a global problem, it is more critical in resource-constrained countries. The national medicines regulatory authorities (MNRA) in these countries have limited resources to cater for regular quality surveillance programmes aimed at ensuring that medicines in circulation are of acceptable quality. Among the reasons explained to hinder the implementation of these strategies is that compendial monographs are too complicated and require expensive infrastructures in terms of environment, equipment and consumables. In this study it was therefore aimed at developing simple, precise, and robust HPLC and HPTLC methods utilizing inexpensive, readily available chemicals (methanol and simple buffers) that can determine the APIs, other API than declared one, and which are capable of impurity profiling. As an outcome of this study, three isocratic and robust HPLC and two HPTLC methods for sulfadoxine, sulfalene, pyrimethamine, primaquine, artesunate, as well as amodiaquine have been developed and validated. All HPLC methods are operated using an isocratic elution mode which means they can be implemented even with a single pump HPLC system and standard C18 columns. The densitometric sulfadoxine/sulfalene and pyrimethamine method utilizes standard TLC plates as well as inexpensive, readily available and safe chemicals (toluene, methanol, and ethyl acetate), while that for artesunate and amodiaquine requires HPTLC plates as well as triethylamine and acetonitrile due to challenges associated with the analysis of amodiaquine and poorly the detectable artesunate. These HPTLC methods can be implemented as alternative to those requiring HPLC equipment e.g. in countries that already have acquired densitometer equipment. It is understood that HPTLC methods are less sensitive, precise and accurate when compared to HPLC methods, but this hindrance can easily be addressed by sending representative samples to third party quality control laboratories where the analytical results are verified using compendial HPLC methods on a regular basis. It is therefore anticipated that the implementation of these methods will not only address the problem of limited resources required for medicines quality control but also increase the number of monitored targeted antimalarial products as well as the number of resource- constrained countries participating in quality monitoring campaigns. Moreover, the experiences and skills acquired within this work will be applied to other API groups, e. g. antibiotics, afterwards. N2 - Trotz der weltweiten Verbreitung gefälschter Arzneimittel und solcher, die nicht die deklarierte Menge an Wirkstoff enthalten, sind vor allem Entwicklungs- und Schwellenländer von dieser Problematik betroffen. Die Arzneimittelüberwachungs- bzw. Zulassungsbehörden dieser Länder verfügen nur über eingeschränkte Möglichkeiten, die Arzneimittelqualität regelmäßig zu überwachen und somit sicherzustellen, dass die im Markt befindlichen Medikamente eine gute Qualität aufweisen. Einer der Gründe hierfür ist unter anderem, dass die in Arzneibüchern beschriebenen Methoden oftmals sehr komplex sind und eine umfassende Laborausstattung, spezielle Geräte oder teure Chemikalien benötigen. In dieser Arbeit wurden einfache, genaue und robuste flüssigchromatographische Methoden entwickelt, die lediglich günstige, überall verfügbare Chemikalien (z. B. Methanol oder einfache Puffersalze) benötigen und mit denen der Gehalt des deklarierten Arzneistoffes, Arzneistoffverwechslungen sowie das Verunreinigungsprofil bestimmt werden kann. Es konnten drei isokratische, robuste flüssigchromatographische sowie zwei dünnschichtchromatographische Methoden zur Bestimmung von Sulfadoxin, Sulfalen, Pyrimethamin, Primaquin, Artesunat sowie Amodiaquin entwickelt und validiert werden. Alle flüssigchromatographischen Methoden arbeiten isokratisch, folglich können sie auch mit sehr einfachen HPLC-Geräten mit beispielsweise nur einem Pumpenkopf genutzt werden. Zudem werden nur einfache, kommerziell erhältliche C18-Säulen benötigt. Die densitometrischen Methoden für Sulfadoxin/Sulfalen sowie Pyrimethamin benötigen standardisierte Dünnschichtchromatographie-Platten sowie günstige, überall verfügbare und wenig toxische Chemikalien wie beispielsweise Toluol, Methanol oder Ethylacetat. Für die Methode zur Bestimmung von Artesunat und Amodiaquin werden Hochleistungsdünnschichtchromatographie-Platten und Triethylamin sowie Acetonitril benötigt. Dieser Umstand ist der Tatsache geschuldet, dass Amodiaquin und Artesunat sich anderweitig nur ungenügend trennen ließen. Die dünnschichtchromatographischen Protokolle können als Alternative zur HPLC eingesetzt werden, beispielsweise überall dort, wo bereits die entsprechenden Gerätschaften vorhanden sind. Natürlich weisen dünnschichtchromatographische Methoden im Vergleich zur Flüssigchromatographie eine geringere Sensitivität, Präzision und Richtigkeit auf, dies kann jedoch dadurch umgangen werden, die entsprechenden Methoden nur zum Screening zu verwenden und die zu analysierenden Proben anderweitig, z. B. in externen Laboratorien, detailliert zu untersuchen. Dort können beispielsweise Methoden aus gängigen Arzneibüchern verwendet werden. Durch die Implementierung der neu entwickelten Methoden kann zum einen das Problem schlecht verfügbarer Chemikalien umgangen werden und gleichzeitig die Anzahl an untersuchten Arzneimitteln erhöht werden. Dies ist ein wichtiger Beitrag zur Qualitätskontrolle in Ländern mit eingeschränkten Infrastrukturen. KW - Instrumentelle Analytik KW - Arzneimittel KW - Fälschung KW - Malaria KW - HPLC KW - Counterfeit Medicines KW - HPLC KW - Pharmaceutical Analysis KW - Impurity Profiling Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145821 ER - TY - THES A1 - Dejure, Francesca Romana T1 - Investigation of the role of MYC as a stress responsive protein T1 - Untersuchung der Rolle von MYC als stress-reguliertes Protein N2 - The transcription factor MYC is deregulated in over 70% of all human tumors and, in its oncogenic form, plays a major role in the cancer metabolic reprogramming, promoting the uptake of nutrients in order to sustain the biosynthetic needs of cancer cells. The research presented in this work aimed to understand if MYC itself is regulated by nutrient availability, focusing on the two major fuels of cancer cells: glucose and glutamine. Initial observations showed that endogenous MYC protein levels strongly depend on the availability of glutamine, but not of glucose. Subsequent analysis highlighted that the mechanism which accounts for the glutamine-mediated regulation of MYC is dependent on the 3´-untranslated region (3´-UTR) of MYC. Enhanced glutamine utilization by tumors has been shown to be directly linked to MYC oncogenic activity and MYC-dependent apoptosis has been observed under glutamine starvation. Such effect has been described in experimental systems which are mainly based on the use of MYC transgenes that do not contain the 3´-UTR. It was observed in the present study that cells are able to survive under glutamine starvation, which leads to cell cycle arrest and not apoptosis, as previously reported. However, enforced expression of a MYC transgene, which lacks the 3´-UTR, strongly increases the percentage of apoptotic cells upon starvation. Evaluation of glutamine-derived metabolites allowed to identify adenosine nucleotides as the specific stimulus responsible for the glutamine-mediated regulation of MYC, in a 3´-UTR-dependent way. Finally, glutamine-dependent MYC-mediated effects on RNA Polymerase II (RNAPII) function were evaluated, since MYC is involved in different steps of global transcriptional regulation. A global loss of RNAPII recruitment at the transcriptional start site results upon glutamine withdrawal. Such effect is overcome by enforced MYC expression under the same condition. This study shows that the 3´UTR of MYC acts as metabolic sensor and that MYC globally regulates the RNAPII function according to the availability of glutamine. The observations presented in this work underline the importance of considering stress-induced mechanisms impinging on the 3´UTR of MYC. N2 - In über 70% aller Krebserkrankungen ist der Transkriptionsfaktor MYC dereguliert. Dabei spielt onkogenes MYC unter anderem eine wichtige Rolle bei der Umprogrammierung metabolischer Prozesse indem es z.B. die Aufnahme von Nährstoffen wie Glutamin oder Glukose fördert, um den veränderten Bedürfnissen an den Stoffwechsel der Krebszellen Rechnung zu tragen. Die im Rahmen dieser Arbeit erzielten Ergebnisse zeigen, dass auch das MYC-Protein selbst durch die Verfügbarkeit von Nährstoffen in der Zelle reguliert werden kann. Erste Beobachtungen zeigten, dass die endogenen MYC Proteinlevel stark von der Verfügbarkeit von Glutamin, jedoch nicht von Glucose, abhängen. Weiterführende Experimente ergaben außerdem, dass der Mechanismus, der der Glutamin vermittelten Regulation von MYC zugrunde liegt, abhängig von der 3´-untranslatierten Region (3´-UTR) der MYC-mRNA ist. Es konnte bereits gezeigt werden, dass in Tumoren die verstärkte Nutzung von Glutamin in direktem Zusammenhang mit der onkogenen Aktivität von MYC steht und Zellen unter Glutaminentzug MYC-abhängig Apoptose einleiten. Diese Effekte wurden in experimentellen Systemen beschrieben, die auf einer Überexpression eines MYCTransgenes basierten, welches keine 3´-UTR enthält. In dieser Arbeit konnte jedoch beobachtet werden, dass Zellen, die ohne Glutamin kultiviert wurden, in der Lage waren zu überleben, da entgegen den Resultaten vorausgegangener Studien, ein Arrest des Zellzyklus und nicht Apoptose eingeleitet wurde. Die verstärkte Expression eines MYCTransgenes ohne 3´-UTR, erhöhte jedoch auch unter diesen Bedingungen die Anzahl apoptotischer Zellen. Weiterhin war es möglich Adenosin, für dessen Biosynthese Glutamin notwendig ist, als Stimulus zu identifizieren, der für die 3´-UTR abhängige Regulation von MYC verantwortlich ist. Da MYC in verschiedene Schritte der globalen Regulation der Transkription eingebunden ist, wurden abschließend die durch MYC vermittelten Glutaminabhängigen Effekte auf die RNA-Polymerase II (RNAPII) untersucht. Dabei zeigte sich, dass es nach Glutaminentzug zu einem globalen Verlust der Rekrutierung von RNAPII zu den Transkriptionsstartstellen kommt, was durch eine verstärkte MYC-Expression wieder aufgehoben werden kann. Zusammenfassend konnte in dieser Arbeit gezeigt werden, dass die 3´-UTR von MYC als metabolischer Sensor fungiert und dass MYC in Abhängigkeit der Verfügbarkeit von Glutamin global die RNAPII Funktion reguliert. Diese Studie hebt weiterhin die Bedeutung der 3´-UTR von MYC für die Vermittlung stressinduzierter Feedback-Mechanismen hervor. KW - cancer KW - metabolism KW - MYC KW - Myc KW - Stress KW - Metabolismus KW - Genregulation KW - Glutamin Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158587 ER -