Publications by authors named "Karin Kiefer"

11 Publications

  • Page 1 of 1

Identification of LC-HRMS nontarget signals in groundwater after source related prioritization.

Water Res 2021 May 2;196:116994. Epub 2021 Mar 2.

Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zurich, Switzerland. Electronic address:

Groundwater is a major drinking water resource but its quality with regard to organic micropollutants (MPs) is insufficiently assessed. Therefore, we aimed to investigate Swiss groundwater more comprehensively using liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). First, samples from 60 sites were classified as having high or low urban or agricultural influence based on 498 target compounds associated with either urban or agricultural sources. Second, all LC-HRMS signals were related to their potential origin (urban, urban and agricultural, agricultural, or not classifiable) based on their occurrence and intensity in the classified samples. A considerable fraction of estimated concentrations associated with urban and/or agricultural sources could not be explained by the 139 detected targets. The most intense nontarget signals were automatically annotated with structure proposals using MetFrag and SIRIUS4/CSI:FingerID with a list of >988,000 compounds. Additionally, suspect screening was performed for 1162 compounds with predicted high groundwater mobility from primarily urban sources. Finally, 12 nontargets and 11 suspects were identified unequivocally (Level 1), while 17 further compounds were tentatively identified (Level 2a/3). amongst these were 13 pollutants thus far not reported in groundwater, such as: the industrial chemicals 2,5-dichlorobenzenesulfonic acid (19 detections, up to 100 ng L), phenylphosponic acid (10 detections, up to 50 ng L), triisopropanolamine borate (2 detections, up to 40 ng L), O-des[2-aminoethyl]-O-carboxymethyl dehydroamlodipine, a transformation product (TP) of the blood pressure regulator amlodipine (17 detections), and the TP SYN542490 of the herbicide metolachlor (Level 3, 33 detections, estimated concentrations up to 100-500 ng L). One monitoring site was far more contaminated than other sites based on estimated total concentrations of potential MPs, which was supported by the elucidation of site-specific nontarget signals such as the carcinogen chlorendic acid, and various naphthalenedisulfonic acids. Many compounds remained unknown, but overall, source related prioritisation proved an effective approach to support identification of compounds in groundwater.
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http://dx.doi.org/10.1016/j.watres.2021.116994DOI Listing
May 2021

Benchmarking of the quantification approaches for the non-targeted screening of micropollutants and their transformation products in groundwater.

Anal Bioanal Chem 2021 Mar 27;413(6):1549-1559. Epub 2021 Jan 27.

Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.

A wide range of micropollutants can be monitored with non-targeted screening; however, the quantification of the newly discovered compounds is challenging. Transformation products (TPs) are especially problematic because analytical standards are rarely available. Here, we compared three quantification approaches for non-target compounds that do not require the availability of analytical standards. The comparison is based on a unique set of concentration data for 341 compounds, mainly pesticides, pharmaceuticals, and their TPs in 31 groundwater samples from Switzerland. The best accuracy was observed with the predicted ionization efficiency-based quantification, the mean error of concentration prediction for the groundwater samples was a factor of 1.8, and all of the 74 micropollutants detected in the groundwater were quantified with an error less than a factor of 10. The quantification of TPs with the parent compounds had significantly lower accuracy (mean error of a factor of 3.8) and could only be applied to a fraction of the detected compounds, while the mean performance (mean error of a factor of 3.2) of the closest eluting standard approach was similar to the parent compound approach.
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http://dx.doi.org/10.1007/s00216-020-03109-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7921029PMC
March 2021

Chlorothalonil transformation products in drinking water resources: Widespread and challenging to abate.

Water Res 2020 Sep 17;183:116066. Epub 2020 Jun 17.

Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092, Zurich, Switzerland. Electronic address:

Chlorothalonil, a fungicide applied for decades worldwide, has recently been banned in the European Union (EU) and Switzerland due to its carcinogenicity and the presence of potentially toxic transformation products (TPs) in groundwater. The spread and concentration range of chlorothalonil TPs in different drinking water resources was examined (73 groundwater and four surface water samples mainly from Switzerland). The chlorothalonil sulfonic acid TPs (R471811, R419492, R417888) occurred more frequently and at higher concentrations (detected in 65-100% of the samples, ≤2200 ngL) than the phenolic TPs (SYN507900, SYN548580, R611968; detected in 10-30% of the samples, ≤130 ngL). The TP R471811 was found in all samples and even in 52% of the samples above 100 ngL, the drinking water standard in Switzerland and other European countries. Therefore, the abatement of chlorothalonil TPs was investigated in laboratory and pilot-scale experiments and along the treatment train of various water works, comprising aquifer recharge, UV disinfection, ozonation, advanced oxidation processes (AOPs), activated carbon treatment, and reverse osmosis. The phenolic TPs can be abated during ozonation (second order rate constant k ∼10 Ms) and by reaction with hydroxyl radicals (OH) in AOPs (k ∼10 Ms). In contrast, the sulfonic acid TPs, which occurred in higher concentrations in drinking water resources, react only very slowly with ozone (k <0.04 Ms) and OH (k <5.0 × 10 Ms) and therefore persist in ozonation and OH-based AOPs. Activated carbon retained the very polar TP R471811 only up to a specific throughput of 25 mkg (20% breakthrough), similarly to the X-ray contrast agent diatrizoic acid. Reverse osmosis was capable of removing all chlorothalonil TPs by ≥98%.
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http://dx.doi.org/10.1016/j.watres.2020.116066DOI Listing
September 2020

Retrospective screening of high-resolution mass spectrometry archived digital samples can improve environmental risk assessment of emerging contaminants: A case study on antifungal azoles.

Environ Int 2020 06 12;139:105708. Epub 2020 Apr 12.

Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092 Zürich, Switzerland. Electronic address:

Environmental risk assessment associated with aquatic and terrestrial contamination is mostly based on predicted or measured environmental concentrations of a limited list of chemicals in a restricted number of environmental compartments. High resolution mass spectrometry (HRMS) can provide a more comprehensive picture of exposure to harmful chemicals, particularly through the retrospective analysis of digitally stored HRMS data. Using this methodology, our study characterized the contamination of various environmental compartments including 154 surface water, 46 urban effluent, 67 sediment, 15 soil, 34 groundwater, 24 biofilm, 41 gammarid and 49 fish samples at 95 sites widely distributed over the Swiss Plateau. As a proof-of-concept, we focused our investigation on antifungal azoles, a class of chemicals of emerging concern due to their endocrine disrupting effects on aquatic organisms and humans. Our results demonstrated the occurrence of antifungal azoles and some of their (bio)transformation products in all the analyzed compartments (0.1-100 ng/L or ng/g d.w.). Comparison of actual and predicted concentrations showed the partial suitability of level 1 fugacity modelling in predicting the exposure to azoles. Risk quotient calculations additionally revealed risk of exposure especially if some of the investigated rivers and streams are used for drinking water production. The case study clearly shows that the retrospective analysis of HRMS/MS data can improve the current knowledge on exposure and the related risks to chemicals of emerging concern and can be effectively employed in the future for such purposes.
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http://dx.doi.org/10.1016/j.envint.2020.105708DOI Listing
June 2020

New relevant pesticide transformation products in groundwater detected using target and suspect screening for agricultural and urban micropollutants with LC-HRMS.

Water Res 2019 Nov 14;165:114972. Epub 2019 Aug 14.

Eawag: Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600, Duebendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, Universitätstrasse 16, ETH Zürich, 8092, Zurich, Switzerland. Electronic address:

Groundwater is a major drinking water resource, but its quality is threatened by a broad variety of anthropogenic micropollutants (MPs), originating from agriculture, industry, or households, and undergoing various transformation processes during subsurface passage. To determine a worst-case impact of pesticide application in agriculture on groundwater quality, a target and suspect screening for more than 300 pesticides and more than 1100 pesticide transformation products (TPs) was performed in 31 Swiss groundwater samples which predominantly originated from areas with intensive agriculture. To assess additional urban contamination sources, more than 250 common urban MPs were quantified. Most of the screened pesticide TPs were experimentally observed by the pesticide producers within the European pesticide registration. To cover very polar pesticide TPs, vacuum-assisted evaporative concentration was used for enrichment, followed by liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). Based on intensity, isotope pattern, retention time, and in silico fragmentation, the suspect hits were prioritised and verified. We identified 22 suspects unequivocally and five tentatively; 13 TPs are reported here for the first time to be detected in groundwater. In 13 out of 31 groundwater samples, the total concentration of the 20 identified and quantified suspects (1 pesticide and 19 pesticide TPs) exceeded the total concentration of the 519 targets (236 pesticides and TPs; 283 urban MPs) for which we screened. Pesticide TPs had higher concentrations than the parent pesticides, illustrating their importance for groundwater quality. The newly identified very polar chlorothalonil TP R471811 was the only compound detected in all samples with concentrations ranging from 3 to 2700 ng/L. Agricultural MP concentration and detection frequency correlated with agricultural land use in the catchment, except for aquifers, where protective top layers reduced MP transport from the surface. In contrast to agricultural MPs, urban MPs displayed almost no correlation with land use. The dominating entry pathway of urban MPs was river bank filtration.
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http://dx.doi.org/10.1016/j.watres.2019.114972DOI Listing
November 2019

Phototriggered fibril-like environments arbitrate cell escapes and migration from endothelial monolayers.

Biomaterials 2016 Mar 17;82:113-23. Epub 2015 Dec 17.

Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany; INM - Leibniz Institute for New Materials, Campus D2 2, 66123, Saarbrücken, Germany; Saarland University, Campus Saarbrücken D2 2, 66123, Saarbrücken, Germany. Electronic address:

Cell detachment and migration from the endothelium occurs during vasculogenesis and also in pathological states. Here, we use a novel approach to trigger single cell release from an endothelial monolayer by in-situ opening of adhesive, fibril-like environment using light-responsive ligands and scanning lasers. Cell escapes from the monolayer were observed on the fibril-like adhesive tracks with 3-15 μm width. The frequency of endothelial cell escapes increased monotonically with the fibril width and with the density of the light-activated adhesive ligand. Interestingly, treatment with VEGF induced cohesiveness within the cell layer, preventing cell leaks. When migrating through the tracks, cells presented body lateral reduction and nuclear deformation imposed by the line width and dependent on myosin contractility. Cell migration mode changed from mesenchymal to amoeboid-like when the adhesive tracks narrowed (≤5 μm). Moreover, cell nucleus was shrunk showing packed DNA on lines narrower than the nuclear dimensions in a mechanisms intimately associated with the stress fibers. This platform allows the detailed study of escapes and migratory transitions of cohesive cells, which are relevant processes in development and during diseases such as organ fibrosis and carcinomas.
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http://dx.doi.org/10.1016/j.biomaterials.2015.12.001DOI Listing
March 2016

Novel glass-like coatings for cardiovascular implant application: Preparation, characterization and cellular interaction.

Mater Sci Eng C Mater Biol Appl 2016 Jan 16;58:812-6. Epub 2015 Sep 16.

Clinic for Pediatric Cardiology, Saarland University, 66421 Homburg, Germany.

Glass coatings are of great interest for biomedical implant application due to their excellent properties. Nowadays they are used in different fields including drug delivery, for bone tissue regeneration or as implant. Nevertheless they can only be applied using high temperatures. Therefore their usage in the field of cardiovascular implant application is still restricted. Accordingly new developments in this field have been carried out to overcome this problem and to coat cardiovascular implants. Here, novel glass-like coatings have been developed and applied using sol-gel technique at moderate temperatures. The biocompatibility and selectivity have been analyzed using human endothelial cells. The obtained results clarify that the developed compositions can either promote or suppress endothelial cell growth only by altering the sintering atmosphere. A later application as thin layer on cardiovascular implants like stents is conceivable.
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http://dx.doi.org/10.1016/j.msec.2015.09.063DOI Listing
January 2016

Alignment of human cardiomyocytes on laser patterned biphasic core/shell nanowire assemblies.

Nanotechnology 2014 Dec 19;25(49):495101. Epub 2014 Nov 19.

Clinic for Paediatric Cardiology, Saarland University, Building 9, 66421 Homburg, Germany.

The management of end stage heart failure patients is only possible by heart transplantation or by the implantation of artificial hearts as a bridge for later transplantation. However, these therapeutic strategies are limited by a lack of donor hearts and by the associated complications, such as coagulation and infection, due to the used artificial mechanical circulatory assist devices. Therefore, new strategies for myocardial regenerative approaches are under extensive research to produce contractile myocardial tissue in the future to replace non-contractile myocardial ischemic and scarred tissue. Different approaches, such as cell transplantation, have been studied intensively. Although successful approaches have been observed, there are still limitations to the application. It is envisaged that myocardial tissue engineering can be used to help replace infarcted non-contractile tissue. The developed tissue should later mimic the aligned fibrillar structure of the extracellular matrix and provide important guidance cues for the survival, function and the needed orientation of cardiomyocytes. Nanostructured surfaces have been tested to provide a guided direction that cells can follow. In the present study, the cellular adhesion/alignment of human cardiomyocytes and the biocompatibility have been investigated after cultivation on different laser-patterned nanowires compared with unmodified nanowires. As a result, the nanostructured surfaces possessed good biocompatibility before and after laser modification. The laser-induced scalability of the pattern enabled the growth and orientation of the adhered myocardial tissue. Such approaches may be used to modify the surface of potential scaffolds to develop myocardial contractile tissue in the future.
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http://dx.doi.org/10.1088/0957-4484/25/49/495101DOI Listing
December 2014

Insect eggs induce a systemic acquired resistance in Arabidopsis.

Plant J 2014 Dec;80(6):1085-94

Department of Plant Molecular Biology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.

Although they constitute an inert stage of the insect's life, eggs trigger plant defences that lead to egg mortality or attraction of egg parasitoids. We recently found that salicylic acid (SA) accumulates in response to oviposition by the Large White butterfly Pieris brassicae, both in local and systemic leaves, and that plants activate a response that is similar to the recognition of pathogen-associated molecular patterns (PAMPs), which are involved in PAMP-triggered immunity (PTI). Here we discovered that natural oviposition by P. brassicae or treatment with egg extract inhibit growth of different Pseudomonas syringae strains in Arabidopsis through the activation of a systemic acquired resistance (SAR). This egg-induced SAR involves the metabolic SAR signal pipecolic acid, depends on ALD1 and FMO1, and is accompanied by a stronger induction of defence genes upon secondary infection. Although P. brassicae larvae showed a reduced performance when feeding on Pseudomonas syringae-infected plants, this effect was less pronounced when infected plants had been previously oviposited. Altogether, our results indicate that egg-induced SAR might have evolved as a strategy to prevent the detrimental effect of bacterial pathogens on feeding larvae.
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http://dx.doi.org/10.1111/tpj.12707DOI Listing
December 2014

Large-scale production of lipoplexes with long shelf-life.

Eur J Pharm Biopharm 2005 Jan;59(1):35-43

Department of Pharmaceutical Technology, Albert-Ludwigs-University, Freiburg, Germany.

The instability of lipoplex formulations is a major obstacle to overcome before their commercial application in gene therapy. In this study, a continuous mixing technique for the large-scale preparation of lipoplexes followed by lyophilisation for increased stability and shelf-life has been developed. Lipoplexes were analysed for transfection efficiency and cytotoxicity in human aorta smooth muscle cells (HASMC) and a rat smooth muscle cell line (A-10 SMC). Homogeneity of lipid/DNA-products was investigated by photon correlation spectroscopy (PCS) and cryotransmission electron microscopy (cryo-TEM). Studies have been undertaken with DAC-30, a composition of 3beta-[N-(N,N'-dimethylaminoethane)-carbamoyl]-cholesterol (DAC-Chol) and dioleylphosphatidylethanolamine (DOPE) and a green fluorescent protein (GFP) expressing marker plasmid. A continuous mixing technique was compared to the small-scale preparation of lipoplexes by pipetting. Individual steps of the continuous mixing process were evaluated in order to optimise the manufacturing technique: lipid/plasmid ratio, composition of transfection medium, pre-treatment of the lipid, size of the mixing device, mixing procedure and the influence of the lyophilisation process. It could be shown that the method developed for production of lipoplexes on a large scale under sterile conditions led to lipoplexes with good transfection efficiencies combined with low cytotoxicity, improved characteristics and long shelf-life.
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http://dx.doi.org/10.1016/j.ejpb.2004.06.001DOI Listing
January 2005

Transfection efficiency and cytotoxicity of nonviral gene transfer reagents in human smooth muscle and endothelial cells.

Pharm Res 2004 Jun;21(6):1009-17

Department of Pharmaceutical Technology, Albert-Ludwigs University, D-79104 Freiburg, Germany.

Purpose: Evaluation of a nonviral transfection reagent with respect to efficient gene transfer into primary human vascular cells.

Methods: Complexes consisting of seven commercially available transfection reagents (DAC-30, DC-30, Lipofectin, LipofectAMINE PLUS, Effectene, FuGene 6 and Superfect) and EGFP encoding plasmid DNA were studied. The in vitro transfection efficiency and cytotoxicity in human aorta smooth muscle cells (HASMCs) and endothelial cells (HAECs) and rat smooth muscle cells (A-10 SMCs) were assayed in the presence of serum using flow cytometric analysis and ATP-quantitation assay, respectively.

Results: Human primary cells were transfected less efficiently compared to the rat smooth muscle cell line. Transfection efficiency depended on the type of reagent, the reagent/DNA ratio, and, most importantly, on the cell type used. Determination of cytotoxicity showed that the effects of transfection on cell viability did not significantly differ from one another depending on the cell type. The exception to this was Superfect, which obviously reduced cell viability in all cell types.

Conclusions: Our experiments showed that DAC-30 is the preferred transfection reagent for HASMCs and HAECs, exhibiting an improved efficiency combined with an acceptable cytotoxicity. Therefore, it might offer a therapeutic option for the treatment of cardiovascular disease and prove suitable for further drug development.
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http://dx.doi.org/10.1023/b:pham.0000029291.62615.ecDOI Listing
June 2004
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