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Software updates are a critical success factor in mobile app ecosystems. Through publishing regular updates, platform providers enhance their operating systems for the benefit of both end users and third-party developers. It is also a way of attracting new customers. However, this platform evolution poses the risk of inadvertently introducing software problems, which can severely disturb the ecosystem’s balance by compromising its foundational technologies. So far, little to no research has addressed this issue from a user-centered perspective. The thesis at hand draws on IS post-adoption literature to investigate the potential negative influences of operating system updates on mobile app users. The release of Apple’s iOS 13 update serves as research object. Based on over half a million user reviews from the AppStore, data mining techniques are applied to study the impact of the new platform version. The results show that iOS 13 caused complications with a large number of popular apps, leading to a significant decline in user ratings and an uptrend in negative sentiment. Feature requests, functional complaints, and device compatibility are identified as the three major issue categories. These issue types are compared in terms of their quantifiable negative effect on users’ continuance intention. In essence, the findings contribute to IS research on post-adoption behavior and provide guidance to ecosystem participants in dealing with update-induced platform issues.
Accumulating evidence suggests that iron homeostasis is disturbed in tumors. We aimed at clarifying the distribution of iron in renal cell carcinoma (RCC). Considering the pivotal role of macrophages for iron homeostasis and their association with poor clinical outcome, we investigated the role of macrophage-secreted iron for tumor progression by applying a novel chelation approach. We applied flow cytometry and multiplex-immunohistochemistry to detect iron-dependent markers and analyzed iron distribution with atomic absorption spectrometry in patients diagnosed with RCC. We further analyzed the functional significance of iron by applying a novel extracellular chelator using RCC cell lines as well as patient-derived primary cells. The expression of iron-regulated genes was significantly elevated in tumors compared to adjacent healthy tissue. Iron retention was detected in tumor cells, whereas tumor-associated macrophages showed an iron-release phenotype accompanied by enhanced expression of ferroportin. We found increased iron amounts in extracellular fluids, which in turn stimulated tumor cell proliferation and migration. In vitro, macrophage-derived iron showed pro-tumor functions, whereas application of an extracellular chelator blocked these effects. Our study provides new insights in iron distribution and iron-handling in RCC. Chelators that specifically scavenge iron in the extracellular space confirmed the importance of macrophage-secreted iron in promoting tumor growth
This PhD thesis is dedicated to the extension of the portfolio of nuclear magnetic resonance (NMR) methods to characterize ribonucleic acids (RNAs). Only within the last few decades it has been realized that the cellular role of RNA goes well beyond the central dogma of molecular biology. In fact, RNA takes part in numerous cellular processes, executes numerous functions and acts either as a single player or in larger complexes, mostly RNA-protein complexes (RNPs) such as the ribosome or the spliceosome. This versatility in RNA function is coupled to a structural variety and the ability to adopt multiple long-lived and intricate conformations. Due to this high molecular complexity special demands are placed on the methods that are required for RNA structural characterization. With the ability to capture dynamics at atomic resolution and to measure under close to native conditions, NMR spectroscopy is undoubtedly a prime method for this purpose.
A general introduction to the current state of research, selected achievements as well as challenges in the field of NMR spectroscopy on RNA is given in Chapter I. This thesis is further composed of three independent chapters covering the three separate projects, which form the main body of work within the course of this thesis.
The imino group found in two of the four RNA nucleobases is generally considered to be the most powerful reporter group in the process of the NMR spectroscopic characterization of RNA. Its resonance assignment provides key information for a rapid determination of the RNA’s secondary structure. This is possible, since the imino proton can only be detected, if it is protected from rapid solvent exchange through hydrogen bonding interactions or, in rare cases, steric shielding. Consequently, information on flexible regions of RNA that are not protected against solvent exchange cannot be derived using this NMR spy. It is a key finding of the thesis that nucleobase interactions can also be mapped through the amino groups, as they similarly take part in base pairing or RNA-ligand interactions. Notably, solvent exchange of the amino protons is always slower compared to the imino proton. Thus, 1H,15N resonances of the amino group can be detected even for dynamic regions of RNA. Moreover, focusing on characterizing amino groups of RNA nucleobases increases the number of available reporters as amino groups are present in three out of four RNA nucleobases.
However, there is a reason that up to work conducted in this thesis, amino groups have not been used for monitoring RNA nucleobases: the rate of the C-NH2 bond rotation is most often close to the chemical shift differences of the two non-identical amino proton resonances, in particular for guanosines and adenosines, amino resonances regularly remain elusive in NMR spectra. Therefore, we developed experiments that excite double quantum (DQ) coherences of the two amino group protons and that further utilize 13C-detection. Results on these experiments are discussed in Chapter II and show that the rotational exchange can be avoided by evolving double quantum instead of single quantum (SQ) coherence in the indirect dimension of a 13C-detected C(N)H-HDQC experiment. The new experiment enables the detection of a full set of sharp amino resonances. The advantages of this experiment are immediately apparent when comparing the number of observable imino resonances in a classic 1H,15N-HSQC spectrum with the number of amino resonances obtained in the 13C-detected C(N)H-HDQC spectrum of the same RNA.
Furthermore, based on the newly available resonance assignment of amino groups, we developed a 13C-detected “amino”-NOESY experiment to obtain precious additional structural restraints. The 13C-detected “amino”-NOESY experiment enables the observation of NOE contacts that are not accessible using other 1H-detected NOESY experiment. Among these new NOE contacts are valuable, inter-residual correlations, which are otherwise scarce in RNA due to the proton deficiency of its nucleobases. We showed that the newly obtained NOE contacts are especially important in the structure determination of RNAs with only few NOE restraints. Under such circumstances, the inclusion of the newly obtained amino NOE contacts lead to a significant improvement in the root-mean-square deviation (RMSD) of the three-dimensional structure of the 34 nts GTP class II aptamer. Together the novel 13C-detected NMR experiments developed within this PhD project provide a valuable alternative for the imino-based characterization of nucleobase interactions.
...
NMR spectroscopy is a potent method for the structural and biophysical characterization of RNAs. The application of NMR spectroscopy is restricted in RNA size and most often requires isotope‐labeled or even selectively labeled RNAs. Additionally, new NMR pulse sequences, such as the heteronuclear‐detected NMR experiments, are introduced. We herein provide detailed protocols for the preparation of isotope‐labeled RNA for NMR spectroscopy via in vitro transcription. This protocol covers all steps, from the preparation of DNA template to the transcription of milligram RNA quantities. Moreover, we present a protocol for a chemo‐enzymatic approach to introduce a single modified nucleotide at any position of any RNA. Regarding NMR methodology, we share protocols for the implementation of a suite of heteronuclear‐detected NMR experiments including 13C‐detected experiments for ribose assignment and amino groups, the CN‐spin filter heteronuclear single quantum coherence (HSQC) for imino groups and the 15N‐detected band‐selective excitation short transient transverse‐relaxation‐optimized spectroscopy (BEST‐TROSY) experiment.
Basic Protocol 1: Preparation of isotope‐labeled RNA samples with in vitro transcription using T7 RNAP, DEAE chromatography, and RP‐HPLC purification
Alternate Protocol 1: Purification of isotope‐labeled RNA from in vitro transcription with preparative PAGE
Alternate Protocol 2: Purification of isotope‐labeled RNA samples from in vitro transcription via centrifugal concentration
Support Protocol 1: Preparation of DNA template from plasmid
Support Protocol 2: Preparation of PCR DNA as template
Support Protocol 3: Preparation of T7 RNA Polymerase (T7 RNAP)
Support Protocol 4: Preparation of yeast inorganic pyrophosphatase (YIPP)
Basic Protocol 2: Preparation of site‐specific labeled RNAs using a chemo‐enzymatic synthesis
Support Protocol 5: Synthesis of modified nucleoside 3′,5′‐bisphosphates
Support Protocol 6: Preparation of T4 RNA Ligase 2
Support Protocol 7: Setup of NMR spectrometer for heteronuclear‐detected NMR experiments
Support Protocol 8: IPAP and DIPAP for homonuclear decoupling
Basic Protocol 3: 13C‐detected 3D (H)CC‐TOCSY, (H)CPC, and (H)CPC‐CCH‐TOCSY experiments for ribose assignment
Basic Protocol 4: 13C‐detected 2D CN‐spin filter HSQC experiment
Basic Protocol 5: 13C‐detected C(N)H‐HDQC experiment for the detection of amino groups
Support Protocol 9: 13C‐detected CN‐HSQC experiment for amino groups
Basic Protocol 6: 13C‐detected “amino”‐NOESY experiment
Basic Protocol 7: 15N‐detected BEST‐TROSY experiment
Background: Lipodystrophy syndromes comprise a group of extremely rare and heterogeneous diseases characterized by a selective loss of adipose tissue in the absence of nutritional deprivation or catabolic state. Because of the rarity of each lipodystrophy subform, research in this area is difficult and international co-operation mandatory. Therefore, in 2016, the European Consortium of Lipodystrophies (ECLip) decided to create a registry for patients with lipodystrophy.
Results: The registry was build using the information technology Open Source Registry System for Rare Diseases in the EU (OSSE), an open-source software and toolbox. Lipodystrophy specific data forms were developed based on current knowledge of typical signs and symptoms of lipodystrophy. The platform complies with the new General Data Protection Regulation (EU) 2016/679 by ensuring patient pseudonymization, informational separation of powers, secure data storage and security of communication, user authentication, person specific access to data, and recording of access granted to any data. Inclusion criteria are all patients with any form of lipodystrophy (with the exception of HIV-associated lipodystrophy). So far 246 patients from nine centres (Amsterdam, Bologna, Izmir, Leipzig, Münster, Moscow, Pisa, Santiago de Compostela, Ulm) have been recruited. With the help from the six centres on the brink of recruitment (Cambridge, Lille, Nicosia, Paris, Porto, Rome) this number is expected to double within the next one or 2 years.
Conclusions: A European registry for all patients with lipodystrophy will provide a platform for improved research in the area of lipodystrophy. All physicians from Europe and neighbouring countries caring for patients with lipodystrophy are invited to participate in the ECLip Registry.
Study registration: ClinicalTrials.gov (NCT03553420). Registered 14 March 2018, retrospectively registered.
Broadly neutralizing antibodies (bNAbs) represent a promising approach to prevent and treat HIV-1 infection. However, viral escape through mutation of the HIV-1 envelope glycoprotein (Env) limits clinical applications. Here we describe 1-18, a new VH1-46-encoded CD4 binding site (CD4bs) bNAb with outstanding breadth (97%) and potency (GeoMean IC50 = 0.048 μg/mL). Notably, 1-18 is not susceptible to typical CD4bs escape mutations and effectively overcomes HIV-1 resistance to other CD4bs bNAbs. Moreover, mutational antigenic profiling uncovered restricted pathways of HIV-1 escape. Of most promise for therapeutic use, even 1-18 alone fully suppressed viremia in HIV-1-infected humanized mice without selecting for resistant viral variants. A 2.5-Å cryo-EM structure of a 1-18-BG505SOSIP.664 Env complex revealed that these characteristics are likely facilitated by a heavy-chain insertion and increased inter-protomer contacts. The ability of 1-18 to effectively restrict HIV-1 escape pathways provides a new option to successfully prevent and treat HIV-1 infection.
Seit der Entdeckung des HI-Virus in 1983, wurden diverse Beobachtungen zu neurologischen Komplikationen bei infizierten Patienten publiziert. Dabei standen initial lebensbedrohliche Komplikationen wie opportunistische Infektionen oder cerebrale Lymphome im Vordergrund. In Zeiten der antiretroviralen Therapie rücken jedoch vermehrt andere, chronisch verlaufende Folgen der Erkrankung in den Fokus. Neurokognitive Störungen bei HIV-infizierten wurden bereits erstmals im Jahre 1986 beschrieben. Seitdem wurden neben der manifesten HIV-assoziierten Demenz auch mildere Einbußen im kongitiven Bereich - sogenannte HIV-assoziierte neurokognitive Störungen (HAND) - klassifiziert, deren Diagnostik mittels diverser neuropsychologischer Testungen erfolgen kann. Hierfür sind geeignete Screening-Tools notwendig, die entsprechenden Anforderungen entsprechen sollten. Einheitliche Empfehlungen für einen bestimmten Test finden sich jedoch in aktuellen Leitlinien und Publikationen nicht. Die vorliegende Arbeit wurde zur Evaluation des MoCA-Tests (Montreal Cognitive Assessment) zur Detektion HIV-1-assoziierter neurokognitiver Störungen angefertigt.
Hierfür wurde der MoCA-Test an 89 HIV-infizierten Männern und Frauen zwischen 21 und 64 Jahren des HIV-Centers Frankfurt am Main durchgeführt und die Ergebnisse mit der gut validierten HIV-Demenz-Skala verglichen. Zudem wurde der Einfluss verschiedener Faktoren wie Geschlecht, Alter, CDC-Stadium, antiretrovirale Therapie, Dauer der HIV-Infektion, CD4-Zellzahl, Viruslast, HCV-Koinfektion, Bildung, Risikogruppenzugehörigkeit, Alkoholkonsum und CPE-Score untersucht.
Der Vergleich zwischen den absoluten Ergebnissen der HDS und des MoCA ergab einen hochsignifikanten statistischen Zusammenhang. Ein statistischer Zusammenhang konnte auch für die Parameter Alter, medikamentöse HIV-Therapie, Dauer der HIV-Infektion zum Untersuchungszeitpunkt sowie Bildung errechnet werden. Die relativen MoCA-Testergebnisse wurden sowohl mit einem Cut-off-Wert von 10 als auch einem Cut-off-Wert von 14 der HDS verglichen.
In Zusammenschau der Ergebnisse korreliert der MoCA-Test auf Grundlage der erhobenen Daten mit der HDS, wobei die Sensitivität in Bezug auf mildere kognitive Störungen niedriger als wünschenswert ist. Eine manifeste HIV-Demenz kann zuverlässig diagnostiziert werden, bei der Diagnostik von milderen Funktionseinschränkungen bestehen jedoch Limitationen. Auf Grund der einfachen Durchführung stellt er ein akzeptables alternatives Screening-Tool dar, wobei Personen mit auffälligen Testergebnissen einer weiteren neuropsychologischen Testung zugeführt werden sollten.
Dieser Band versammelt die Vorträge einer Tagung der Johannes- Althusius-Gesellschaft e. V., die vom 26.–29.5.2016 in Wittenberg stattfand.
Die umfassende Thematik wurde auf vier Aspekte konzentriert: 1) Religion und Konstitutionalisierung 2) die Bedeutung der Reformation für Rechts- und Staatslehren der frühen Neuzeit, 3) Völkerrecht, 4) Recht, Gehorsam und Religion. Dem folgt auch die Gliederung des Buches. Leider ist die Einleitung des Herausgebers sehr formal. Angesichts einiger sehr anregender neuer Forschungsthesen bzw. -ergebnisse wäre der inhaltliche Schwung der Tagung gleich als Eröffnung gut vermittelbar gewesen. ...
La creación de audio-podcasts ofrece una excelente oportunidad para representar de forma oral los contenidos de matemáticas usando medios digitales tanto en la formación docente, como en la educación primaria. Sin embargo, en el proceso de creación de los audio- -podcasts hay fases gráficas-escritas y otras orales que están estrechamente vinculadas entre sí. Este artículo trata sobre la creación y utilización de podcast en la educación primaria (PriMaPodcast) y en la formación docente (MathePodcast) tanto para la enseñanza como para la investigación.Mathematics audio-podcasts: communication and representation with ICTLa creación de audio-podcasts ofrece una excelente oportunidad para representar de forma oral los contenidos de matemáticas usando medios digitales tanto en la formación docente, como en la educación primaria. Sin embargo, en el proceso de creación de los audio- -podcasts hay fases gráficas-escritas y otras orales que están estrechamente vinculadas entre sí. Este artículo trata sobre la creación y utilización de podcast en la educación primaria (PriMaPodcast) y en la formación docente (MathePodcast) tanto para la enseñanza como para la investigación.