Publications by authors named "Ippel J"

Platelet activation contributes to sepsis development, leading to microthrombosis and increased inflammation, which results in disseminated intravascular coagulation and multiple organ dysfunction. Although Cathelicidin can alleviate sepsis, its role in sepsis regulation remains largely unexplored. In this study, we identified Cath-HG, a novel Cathelicidin from skin, and analyzed its structure using nuclear magnetic resonance spectroscopy.

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Introduction: Exposure to osimertinib, a third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) for treatment of non-small cell lung cancer (NSCLC) and a sensitizing EGFR mutation, can be substantially below average. We evaluated whether plasma levels could be boosted by co-administration of cobicistat, a strong Cytochrome P450 3A-inhibitor.

Methods: This was a pharmacokinetic, proof-of-concept clinical trial (the OSIBOOST trial, NCT03858491).

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While substantial efforts have been made to optimize and standardize fecal metabolomics for studies in adults, the development of a standard protocol to analyze infant feces is, however, still lagging behind. Here, we present the development of a hands-on and robust protocol for proton H NMR spectroscopy of infant feces. The influence of extraction solvent, dilution ratio, homogenization method, filtration, and duration of centrifugation on the biochemical composition of infant feces was carefully evaluated using visual inspection of H NMR spectra in combination with multivariate statistical modeling.

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During feeding, a tick's mouthpart penetrates the host's skin and damages tissues and small blood vessels, triggering the extrinsic coagulation and lectin complement pathways. To elude these defense mechanisms, ticks secrete multiple anticoagulant proteins and complement system inhibitors in their saliva. Here, we characterized the inhibitory activities of the homologous tick salivary proteins tick salivary lectin pathway inhibitor, Salp14, and Salp9Pac from Ixodesscapularis in the coagulation cascade and the lectin complement pathway.

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Ticks, as blood-sucking parasites, have developed a complex strategy to evade and suppress host immune responses during feeding. The crucial part of this strategy is expression of a broad family of salivary proteins, called Evasins, to neutralize chemokines responsible for cell trafficking and recruitment. However, structural information about Evasins is still scarce, and little is known about the structural determinants of their binding mechanism to chemokines.

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Atherosclerosis is one of the leading causes of mortality in developed and developing countries. The onset of atherosclerosis development is accompanied by overexpression of several inflammatory chemokines. Neutralization of these chemokines by chemokine-binding agents attenuates atherosclerosis progression.

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Chemokines are a group of chemotaxis proteins that regulate cell trafficking and play important roles in immune responses and inflammation. Ticks are blood-sucking parasites that secrete numerous immune-modulatory agents in their saliva to evade host immune responses. Evasin-3 is a small salivary protein that belongs to a class of chemokine-binding proteins isolated from the brown dog tick, Evasin-3 has been shown to have a high affinity for chemokines CXCL1 and CXCL8 and to diminish inflammation in mice.

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In Nature, multicyclic peptides constitute a versatile molecule class with various biological functions. For their pharmaceutical exploitation, chemical methodologies that enable selective consecutive macrocyclizations are required. We disclose a combination of enzymatic macrocyclization, CLIPS alkylation, and oxime ligation to prepare tetracyclic peptides.

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Selenocysteine scanning (SecScan) is a novel technique to map disulfide networks in proteins independent of structure-based distance information and mass spectrometry. SecScan applies systematic substitution of single Cys by Sec in combination with NMR spectroscopy for reliable and unambiguous determination of disulfide bond networks.

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Accurate time-resolved temperature mapping is crucial for the safe use of hyperthermia-mediated drug delivery. We here propose a magnetic resonance imaging temperature mapping method in which drug delivery systems serve not only to improve tumor targeting, but also as an accurate and absolute nano-thermometer. This method is based on the temperature-dependent chemical shift difference between water protons and the protons in different groups of drug delivery systems.

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The tricarboxylic acid citric acid is a key intermediary metabolite in organisms from all domains of the tree of life. Surprisingly, this metabolite specifically interacts with the light-induced signaling state of the photoactive yellow protein (PYP), such that, at 30 mM, it retards recovery of this state to the stable ground state of the protein with up to 30%, in the range from pH 4.5 to pH 7.

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Object: Proton resonance frequency shift (PRFS)-based MR thermometry (MRT) is hampered by heat-induced susceptibility changes when applied in tissues containing fat, e.g., the human breast.

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Complement factor C5a is one of the most powerful pro-inflammatory agents involved in recruitment of leukocytes, activation of phagocytes and other inflammatory responses. C5a triggers inflammatory responses by binding to its G-protein-coupled C5a-receptor (C5aR). Excessive or erroneous activation of the C5aR has been implicated in numerous inflammatory diseases.

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Insight into the hyperthermostable endo-beta-1,3-glucanase pfLamA from Pyrococcus furiosus is obtained by using NMR spectroscopy. pfLamA functions optimally at 104 degrees C and recently the X-ray structure of pfLamA has been obtained at 20 degrees C, a temperature at which the enzyme is inactive. In this study, near-complete (>99%) NMR assignments are presented of chemical shifts of pfLamA in presence and absence of calcium at 62 degrees C, a temperature at which the enzyme is biologically active.

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In this communication, a new site specific synthesis of highly functionalized and multiple sulfated peptides using convential Fmoc-tBu solid phase peptide synthesis is described.

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Complement component C5a is a potent pro-inflammatory agent inducing chemotaxis of leukocytes toward sites of infection and injury. C5a mediates its effects via its G protein-coupled C5a receptor (C5aR). Although under normal conditions highly beneficial, excessive levels of C5a can be deleterious to the host and have been related to numerous inflammatory diseases.

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Isotope labelling of proteins is important for progress in the field of structural proteomics. It enables the utilisation of the power of nuclear magnetic resonance spectroscopy (NMR) for the characterisation of the three-dimensional structures and corresponding dynamical features of proteins. The usual approach to obtain isotopically labelled protein molecules is by expressing the corresponding gene in bacterial or yeast host organisms, which grow on isotope-enriched media.

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The human plasma protein transthyretin (TTR) may form fibrillar protein deposits that are associated with both inherited and idiopathic amyloidosis. The present study utilizes solution nuclear magnetic resonance spectroscopy, in combination with hydrogen/deuterium exchange, to determine residue-specific solvent protection factors within the fibrillar structure of the clinically relevant variant, TTRY114C. This novel approach suggests a fibril core comprised of the six beta-strands, A-B-E-F-G-H, which retains a native-like conformation.

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Amyloid is the result of an anomalous protein and peptide aggregation, leading to the formation of insoluble fibril deposits. At present, 18 human diseases have been associated with amyloid deposits-e.g.

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The solution structure of a DNA three-way junction (3H) containing two unpaired thymidine bases at the branch site (3HT2), was determined by NMR. Arms A and B of the 3HT2 form a quasi-continuous stacked helix, which is underwound at the junction and has an increased helical rise. The unstacked arm C forms an acute angle of approximately 55 degrees with the unique arm A.

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In budding yeast, MEC1 and RAD53 are essential for cell growth. Previously we reported that mec1 or rad53 lethality is suppressed by removal of Sml1, a protein that binds to the large subunit of ribonucleotide reductase (Rnr1) and inhibits RNR activity. To understand further the relationship between this suppression and the Sml1-Rnr1 interaction, we randomly mutagenized the SML1 open reading frame.

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The circular DNA decamer 5'-d-3' was studied in solution by means of NMR spectroscopy and molecular dynamics in H2O. At a temperature of 269 K, a 50/50 mixture of two dumbbell structures (denoted L2L2 and L2L4) is present. The L2L2 form contains three Watson-Crick C-G base pairs and two two-residue loops is opposite parts of the molecule.

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The conformational behavior of DNA minihairpin loops is sensitive to the directionality of the base pair that closes the loop. Especially tailored circular dumbbells, consisting of a stem of three Watson-Crick base pairs capped on each side with a minihairpin loop, serve as excellent model compounds by means of which deeper insight is gained into the relative stability and melting properties of hairpin loops that differ only in directionality of the closing pair: C-G vs G-C. For this reason the thermodynamic properties of the circular DNA decamers 5'-d-3' (I) and reference compounds 5'-d-3' (II) and 5'-d(GCG-TC-CGC)-3' (III) are studied by means of nmr spectroscopy.

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