The effect of pattern recognition receptor RIG-I variant expression during mammalian- or avian-adapted influenza A infection and adaptation in the mouse.

Influenza A virus infections are common all over the world and cause substantial damage on health and economy by seasonal outbreaks. The infectious disease flu becomes even more life threatening when followed by a secondary bacterial infection, for which especially children and immune-suppressed people are susceptible. Today, the annually adapted influenza vaccination is an important tool to prevent outbreaks of flu. Medical treatments of acute infections are limited with the exceptions of therapeutically targeting the viral proteins neuraminidase and M2. A deeper understanding of the molecular mechanisms of the IAV pathogenicity and antiviral defense mechanisms, as well as their interaction, can help to refine vaccination strategies and direct therapeutic options to generate more target specific and effective antiviral drugs. The pattern recognition receptor RIG-I is one of the most important sensors of the innate immune system to detect foreign RNAs. Upon the binding of RNA ligands like the panhandle structures of influenza A virus, RIG-I amongst others mediates the expression of interferon type 1 and interleukin-1β in an ATPase dependent manner. Additionally, the binding of RIG-I to the viral panhandle structures is confirmed in vitro as another antiviral function by blocking the access for the viral polymerase, as firstly described by Friedemann Weber in the year 2015. The main aim of this thesis was to investigate the contribution of the different antiviral effects of RIG-I against the influenza A virus in a mouse infection model. Furthermore, additional insights about the RIG-I blocking function should be gained. Therefore, a mouse line deficient in RIG-I signaling and another one lacking RIG-I expression were established with the help of genetic engineering. Additionally, two recombinant influenza strains harboring an adaptation in the viral polymerase gene either to mammalian hosts or to avian hosts (polymerase subunit 2 codon 627K and 627E) were generated. Both virus strains were validated for different quality features. The recombinant virus strains were used to perform an infection study using RIG-I wild type, signaling-deficient and knockout mice. Investigating the effect of RIG-I variant expression on parameters like weight reduction, lung virus titer, loss of lung barrier integrity, interferon and cytokine concentration in response to the influenza A infection, new insights in the antiviral functions of RIG-I were gained. The established mouse lines expressing signaling-deficient or no RIG-I did not develop any detectable burden by their genotype. The RIG-I-mediated interferon-α induction was found to be abolished in bone marrow derived macrophages of mice with signaling deficiency in RIG-I as well as RIG-I knockout mice while it was intact in RIG-I wild type mouse derived cells, as expected. Hence, an unburdened mouse line with RIG-I signaling deficiency and one with a RIG-I knockout were generated. The RIG-I PM line is the first of its kind. While the generation of a mammalian-adapted recombinant influenza A strain was successful from the beginning, the generation of the avian-adapted strain was not successful in mammalian cells. A sufficient replication of both strains was achieved in the DF-1 chicken cell line. The received stock preparations showed similar abilities and the stability of their respective genotype was confirmed over several passages in different cell lines. While the infection of mice with the generated recombinant influenza A strains led to a significant change in observed infection parameters and cytokine signaling, only a weak effect of RIG-I variant expression on the infection parameters was detectable. Additionally, the results deliver hints for a RIG-I dependent induction of IFN-γ by RIG-I, which was not described in detail yet. The data also suggest that the antiviral functions of RIG-I may be potently inhibited by the viral nonstructural protein 1 and the mammalian-adapted polymerase variant. The validation of the genetic stability of the virus strain with the avian-adapted polymerase variant in vivo indicates a significant back mutation to the original mammalian-adapted genotype over the course of the infection. This was significantly affected by the time post infection and the type of RIG I variant expression. A lower rate of back mutation than in RIG-I wild type mice was detected in mice with RIG-I signaling deficiency and the lowest in mice with RIG-I knockout. These findings suggests that both the RIG-I signaling functions and the RIG-I blocking function mediate a selective pressure on the influenza A polymerase subunit 2 codon 627. This conclusion is supported by the results of an in vitro competitive infection assay with both virus variants together, showing a replication advantage of the mammalian-adapted polymerase variant over the avian-adapted variant that is affected by the type of RIG-I expression. Taken together, the results of this study deliver deep insights into the interaction between the innate pattern recognition receptor RIG-I and the influenza A virus. The findings suggest that the presence of RIG-I forces viral polymerase variants common in avian to adapt to a mammalian host. Further, the study delivers additional data confirming a RIG-I-mediated antiviral effect by blocking the access of the viral polymerase to the panhandle structures of viral RNAs. Additionally, the data suggests a high potency of the nonstructural protein 1 and the mammalian-adapted polymerase subunit 2 codon 627K to prevent the effects of RIG-I. The finding that RIG-I may contribute to interferon-γ release could be interesting and should be investigated in future studies, since this interaction is poorly described in the literature, but connects two important features of the innate immune system

Acceptor-Substituted Cyclopentadienyl Compounds

Efficient methodologies for the synthesis of acceptor-substituted perfunctionalized cyclopentadienyl (Cp) compounds were investigated. A facile multigram, one-pot synthesis of [FeC10(HgO2CC3H7)10] from ferrocene and Hg(O2CC3H7)2 is reported. In the corresponding compound, the Hg-C bonds are inert towards oxygen, moisture and even strong Brønsted acids like trifluoroacetic acid and [C5F5NH][SbF6]. Instead, protonation of the carboxylic groups is observed yielding [FeC10(HgO2CCF3)10] and [FeC10Hg10(C5F5N)n][SbF6]10. In the compound [FeC10Hg10(C5F5N)n][SbF6]10, the labile C5F5N ligands are readily displaced by MeCN or tetrahydrothiophene (THT) to afford rare examples of organometallic decacations [FeC10(HgL)10][SbF6]10 (L = MeCN, THT). Electrochemical investigations on the (soluble) permercurated compounds reveal increasing redox potentials of the corresponding Fe(II)/Fe(III) redox couples with increasing Lewis acidity of the Hg-sites. The isolation of the oxidized forms was realized by reaction with [NO]+ or [NO2]+ salts or MoF6. Furthermore, the first crystallographic characterization of permetalated aromatic compounds [FeC10(HgX)10] (X = Cl, O2CCF3, O2CCCl3), [FeC10(HgTHT)10][SbF6]10 and [FeC10(HgMeCN)10][SbF6]10[MoF6] is presented. Complete halodemercuration is observed in the reaction of [FeC10(HgO2CC3H7)10] with K[Br3] followed by halogenation with FeBr3 and elemental Br2. An oxidation potential of E1/2 = 1.1V renders the corresponding ferrocenium cation as potent oxidizing agent. The isolation is realized by reaction of [FeC10Br10] with AsF5. Further functionalization of [FeC10Br10] is achieved by metalation with elemental Mg or by lithium-halogen-exchange with tBuLi. Quenching experiments with dimethylsilylchloride (DMSCl) yielded polysilylated compounds. Full functionalization was achieved after multiple metalation-silylation sequences. The resulting product [FeC10DMS10] displays the first example of a persilylated metallocene. A series of polysilylated derivatives [FeC10DMSnH10-n] (n = 7, 8, 9, 10) is analyzed by CV, single-crystal XRD, NMR and UV/VIS spectroscopy to evaluate the effect of silylation on the electronic properties of metallocenes. The obtained data are supported by quantum-chemical calculations. In the context of perhalogenated Cp compounds, the reaction of C5X6 (X = Cl, Br) with AsF5 and SbF5 is investigated. Here, the formation of unprecedented [2+2]-cycloaddition products of two Cp cations [C5X5]+ is observed. The obtained dications [C10X10]2+ are analyzed by XRD and NMR spectroscopy. DFT calculations reveal that the dimerzation to [2+2]- instead of [2+4]-products is thermodynamically preferred due to the formation of two allylic p-electron systems. Furthermore, in cooperation with the group of Prof. Dr. Schulz the electrochemical properties of [C5(C6F5)5]+ are presented

Laserscanner für den mobilen Einsatz im Bahnbereich

Die ZHAW-Zentren für Signalverarbeitung und Nachrichtentechnik (ZSN) sowie Mathematik und Physik (ZAMP) haben zusammen mit der Firma ELAG Elektronik AG einen 2D-Laserdistanzscanner für den Einsatz im Bahnbereich entwickelt, der auf dem Phasenmessverfahren basiert. Mit dem neuen Laserscanner können Distanzen < 10 m zu schwach reflektierenden Objekten wie z.B. dem Fahrdraht auf 1-2 mm genau gemessen werden, und das bis 500‘000 Mal pro Sekunde.

New approaches for automated data processing of annually laminated sediments

International audienceLaminated sediments, like evaporites and biogenic lake sediments, provide high-resolution paleo-climate records. Yet detection and counting of laminae causes still problems because sedimentary structures are often disturbed. In the past laminated rocks often were analysed manually - a tedious and subjective work. The present study describes four automated approaches for lamina detection based on 1d grey-scale vectors. Best results are obtained with a newly developed algorithm, called Adaptive Template Method (ATM) in combination with the Hilbert transform. ATM improves the signal to noise ratio of the grey-value signal. Its basic idea is to extract first a characteristic waveform, the template, which describes the typical grey-value variation transverse to the laminae. This is a kind of "template learning" process, which in practice is done by an appropriate averaging method. This template is in a second step used for processing the whole sample. One calculates the overlap of the template with the actual signal, the grey-value variation along the core, as function of position in core direction. This method generates a new signal with maxima at positions, where the template optimally matches the original signal. The new time-series is called AT-transform. It is smoother than the initial data sequence. High frequency noise and local trend effects are suppressed. Afterwards, the AT-transform can be analysed with the Hilbert transformation for extracting phase information. The data processing methods are tested both on artificial data sequences and on a seasonally laminated sedimentary record of the Oligocene Baruth Maar (Germany). Although ATM is no panacea for highly disturbed signals, our comparison with other approaches shows that it provides the best results. The combination of ATM and the Hilbert transform allows to detect clearly long-term oscillations in the sedimentation patterns and thus cycles in climatic variations

Changes of the patient management in dentistry during the pandemic caused by the SARS-Coronavirus 2-initial perspectives of a clinic of operative dentistry in Europe

(...

Do avalanche airbags lead to riskier choices in the backcountry?

While the effectiveness of airbags for reducing mortality in avalanche involvements has been examined in various studies, the nagging question of whether the added safety benefit might actually lead to increased risk-taking – a phenomenon referred to as risk compensation or risk homeostasis – has only been tackled by a few. Building on the existing research on airbags, risk compensation and stated terrain preferences in winter backcountry recreation, we developed an extensive online survey to approach the topic of avalanche airbags and risk compensation from multiple directions. In the spring of 2017, 155 airbag owners and 237 non-owners mainly from Switzerland, Germany and Austria participated in our study. While our analysis of the survey responses indicates that risk compensation behavior in response to airbags is likely among recreational backcountry travelers, the discrete choice experiment included in our survey failed to provide conclusive empirical evidence. To allow backcountry users to make informed choices about airbag use, we recommend the topic of risk compensation to be included in avalanche safety courses and airbag user manuals

Do avalanche airbags lead to riskier choices among backcountry and out-of-bounds skiers?

While the effectiveness of airbags for reducing mortality in avalanche involvements has been examined in various studies, the question of whether the added safety benefit might lead to increased risk-taking – a phenomenon referred to as risk compensation or risk homeostasis – has only been tackled by a few researchers. Building on the existing research on airbags, risk compensation, and stated terrain preferences in winter backcountry recreation, we conducted an extensive online survey including a discrete choice experiment to approach the topic of avalanche airbags and risk compensation from multiple perspectives. Our study sample consists of 163 airbag owners and 243 non-owners mainly from Switzerland, Germany, and Austria. The analyses of the survey responses provide both indirect and direct evidence that risk compensation in response to avalanche airbags is likely within at least certain segments of the recreational backcountry and out-of-bounds skiing population. Initial indirect evidence on risk compensation is provided by examining participants’ responses to airbag attitude and use questions using the framework of Hedlund (2000). The stated terrain preferences in our discrete choice experiment with and without airbags indicate that non-owners of airbags might make more aggressive terrain choices when they are given an airbag, whereas the preference patterns of owners did not change when the airbag was taken away from them. Finally, our analysis of avalanche involvement rates with and without airbags offers the most direct evidence that more thrill-seeking backcountry users are taking higher risks when equipped with airbags. The paper concludes with a discussion that highlights that the potential for risk compensation is not a strong argument against the use of avalanche airbags