Publications by authors named "Maria Wilhelm"

5 Publications

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The RESOLUTE consortium: unlocking SLC transporters for drug discovery.

Authors:
Giulio Superti-Furga Daniel Lackner Tabea Wiedmer Alvaro Ingles-Prieto Barbara Barbosa Enrico Girardi Ulrich Goldmann Bettina Gürtl Kristaps Klavins Christoph Klimek Sabrina Lindinger Eva Liñeiro-Retes André C Müller Svenja Onstein Gregor Redinger Daniela Reil Vitaly Sedlyarov Gernot Wolf Matthew Crawford Robert Everley David Hepworth Shenping Liu Stephen Noell Mary Piotrowski Robert Stanton Hui Zhang Salvatore Corallino Andrea Faedo Maria Insidioso Giovanna Maresca Loredana Redaelli Francesca Sassone Lia Scarabottolo Michela Stucchi Paola Tarroni Sara Tremolada Helena Batoulis Andreas Becker Eckhard Bender Yung-Ning Chang Alexander Ehrmann Anke Müller-Fahrnow Vera Pütter Diana Zindel Bradford Hamilton Martin Lenter Diana Santacruz Coralie Viollet Charles Whitehurst Kai Johnsson Philipp Leippe Birgit Baumgarten Lena Chang Yvonne Ibig Martin Pfeifer Jürgen Reinhardt Julian Schönbett Paul Selzer Klaus Seuwen Charles Bettembourg Bruno Biton Jörg Czech Hélène de Foucauld Michel Didier Thomas Licher Vincent Mikol Antje Pommereau Frédéric Puech Veeranagouda Yaligara Aled Edwards Brandon J Bongers Laura H Heitman Ad P IJzerman Huub J Sijben Gerard J P van Westen Justine Grixti Douglas B Kell Farah Mughal Neil Swainston Marina Wright-Muelas Tina Bohstedt Nicola Burgess-Brown Liz Carpenter Katharina Dürr Jesper Hansen Andreea Scacioc Giulia Banci Claire Colas Daniela Digles Gerhard Ecker Barbara Füzi Viktoria Gamsjäger Melanie Grandits Riccardo Martini Florentina Troger Patrick Altermatt Cédric Doucerain Franz Dürrenberger Vania Manolova Anna-Lena Steck Hanna Sundström Maria Wilhelm Claire M Steppan

Nat Rev Drug Discov 2020 07;19(7):429-430

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http://dx.doi.org/10.1038/d41573-020-00056-6DOI Listing
July 2020

Assessment of Dextran Antigenicity of Intravenous Iron Preparations with Enzyme-Linked Immunosorbent Assay (ELISA).

Int J Mol Sci 2016 Jul 21;17(7). Epub 2016 Jul 21.

Global Medical Affairs, Vifor Pharma Ltd., 8152 Glattbrugg, Switzerland.

Intravenous iron preparations are typically classified as non-dextran-based or dextran/dextran-based complexes. The carbohydrate shell for each of these preparations is unique and is key in determining the various physicochemical properties, the metabolic pathway, and the immunogenicity of the iron-carbohydrate complex. As intravenous dextran can cause severe, antibody-mediated dextran-induced anaphylactic reactions (DIAR), the purpose of this study was to explore the potential of various intravenous iron preparations, non-dextran-based or dextran/dextran-based, to induce these reactions. An IgG-isotype mouse monoclonal anti-dextran antibody (5E7H3) and an enzyme-linked immunosorbent assay (ELISA) were developed to investigate the dextran antigenicity of low molecular weight iron dextran, ferumoxytol, iron isomaltoside 1000, ferric gluconate, iron sucrose and ferric carboxymaltose, as well as isomaltoside 1000, the isolated carbohydrate component of iron isomaltoside 1000. Low molecular weight iron dextran, as well as dextran-based ferumoxytol and iron isomaltoside 1000, reacted with 5E7H3, whereas ferric carboxymaltose, iron sucrose, sodium ferric gluconate, and isolated isomaltoside 1000 did not. Consistent results were obtained with reverse single radial immunodiffusion assay. The results strongly support the hypothesis that, while the carbohydrate alone (isomaltoside 1000) does not form immune complexes with anti-dextran antibodies, iron isomaltoside 1000 complex reacts with anti-dextran antibodies by forming multivalent immune complexes. Moreover, non-dextran based preparations, such as iron sucrose and ferric carboxymaltose, do not react with anti-dextran antibodies. This assay allows to assess the theoretical possibility of a substance to induce antibody-mediated DIARs. Nevertheless, as this is only one possible mechanism that may cause a hypersensitivity reaction, a broader set of assays will be required to get an understanding of the mechanisms that may lead to intravenous iron-induced hypersensitivity reactions.
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http://dx.doi.org/10.3390/ijms17071185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4964554PMC
July 2016

Physico-chemical properties of the new generation IV iron preparations ferumoxytol, iron isomaltoside 1000 and ferric carboxymaltose.

Biometals 2015 Aug 24;28(4):615-35. Epub 2015 Mar 24.

Chemical and Preclinical Research and Development, Vifor (International) Ltd., St. Gallen, Switzerland.

The advantage of the new generation IV iron preparations ferric carboxymaltose (FCM), ferumoxytol (FMX), and iron isomaltoside 1000 (IIM) is that they can be administered in relatively high doses in a short period of time. We investigated the physico-chemical properties of these preparations and compared them with those of the older preparations iron sucrose (IS), sodium ferric gluconate (SFG), and low molecular weight iron dextran (LMWID). Mössbauer spectroscopy, X-ray diffraction, and Fe K-edge X-ray absorption near edge structure spectroscopy indicated akaganeite structures (β-FeOOH) for the cores of FCM, IIM and IS, and a maghemite (γ-Fe2O3) structure for that of FMX. Nuclear magnetic resonance studies confirmed the structure of the carbohydrate of FMX as a reduced, carboxymethylated, low molecular weight dextran, and that of IIM as a reduced Dextran 1000. Polarography yielded significantly different fingerprints of the investigated compounds. Reductive degradation kinetics of FMX was faster than that of FCM and IIM, which is in contrast to the high stability of FMX towards acid degradation. The labile iron content, i.e. the amount of iron that is only weakly bound in the polynuclear iron core, was assessed by a qualitative test that confirmed decreasing labile iron contents in the order SFG ≈ IS > LMWID ≥ FMX ≈ IIM ≈ FCM. The presented data are a step forward in the characterization of these non-biological complex drugs, which is a prerequisite to understand their cellular uptake mechanisms and the relationship between the structure and physiological safety as well as efficacy of these complexes.
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http://dx.doi.org/10.1007/s10534-015-9845-9DOI Listing
August 2015

The iron-based phosphate binder PA21 has potent phosphate binding capacity and minimal iron release across a physiological pH range in vitro.

Clin Nephrol 2014 Apr;81(4):251-8

Vifor (International) Inc., St. Gallen, and Vifor Pharma, Glattbrugg, Switzerland.

Aims: Hyperphosphatemia in advanced chronic kidney disease (CKD) necessitates the use of phosphate binders. This in vitro study assessed phosphate binding and Fe release properties of the novel iron-based phosphate binder PA21.

Materials And Methods: Phosphate adsorption and Fe release were assessed under conditions simulating administration of PA21 on an empty stomach and full stomach across a pH range to which PA21 would be exposed during passage through the gastrointestinal (GI) tract.

Results: PA21 showed a robust phosphate binding capacity over the entire physiologically relevant pH range. The high binding capacity at low pH indicates that phosphate binding could begin in the stomach. Under the current experimental setting, the maximal bound phosphate to Fe ratio was 0.47 mmol P/mmol Fe. The largest amount of Fe release was observed at the lowest pH without phosphate and was much lower in the presence of phosphate. These results are in line with the formation of iron phosphate at low pH, as indicated by X-ray photoelectron spectroscopy and thermodynamic calculations. Fe release was minimal (≤ 0.35%) across pH 2.5 - 8.5.

Conclusions: These studies demonstrate that PA21 has potent phosphate binding capacity and low iron release over a physiologically relevant pH range in the GI tract. These features indicate PA21 could be an effective alternative phosphate binder for CKD patients.
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http://dx.doi.org/10.5414/cn108119DOI Listing
April 2014

Determination of oxygen permeability/transmissibility and storage of contact lenses using HPLC with reductive electrochemical detection in combination with a specifically designed sampling unit.

Anal Chem 2003 Mar;75(6):1374-81

Institut für Analytische Chemie und Radiochemie, Universität Innsbruck, Innrain 52 a, A-6020 Innsbruck, Austria.

A new analytical technique for the determination of oxygen permeability/transmissibility of contact lenses is presented in this paper. The method is based on high performance liquid chromatography (HPLC) with reductive electrochemical detection at -750 mV (vs Ag/AgCl) in combination with a patented sampling chamber that was designed especially for the purpose to determine oxygen at nanomolar levels. Compared to conventional method, the new technique exhibits higher sensitivity, selectivity, and versatility. The method permits the selective determination of oxygen permeability (Dk/L)/transmissibility (Dk) of soft as well as rigid contact lenses with good agreement with the Dk/L (Dk) values reported in the literature. Precision was determined by repeated measurements and yielded relative standard deviations of 3-8% for hydrophile lenses and 5-13% for rigid contact lenses. Because of the extraordinarily high sensitivity of the chromatographic oxygen sensor for the first time, the capability of hydrogel lenses to store oxygen could also be directly monitored.
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http://dx.doi.org/10.1021/ac0204395DOI Listing
March 2003