Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

    We have a manual that explains all the features 

Records 1 - 20 / 246

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: q=Leen
Check title to add to marked list
A Fast Quantitative Multi-analyte Method for Growth Promoters in Bovine Meat Using Bead-Disruption, 96-well SPE Clean-up and Narrow-Bore UHPLC-MS/MS Analysis
Tricht, Frederike van; Essers, Martien ; Groot, Maria ; Sterk, Saskia ; Blokland, Marco ; Ginkel, Leen van - \ 2018
Food Analytical Methods 11 (2018)8. - ISSN 1936-9751 - p. 2206 - 2217.
96-wells SPE - Bead-disruption - Bovine meat - Growth promoters - Multi-analyte analysis - UHPLC-MS/MS
A new method for detecting low levels of growth promoters in bovine meat was developed with the following goal: easy, fast and sensitive analysis of a wide range of compounds, with reduced consumption of chemicals and disposables. Several classes of growth promoters were included, i.e. resorcylic acid lactones (RALs) and steroids, the latter including corticosteroids and gestagens. For sample treatment, 0.5 g of homogenised bovine meat was simultaneously disrupted and extracted in a bead-ruptor machine. The organic extraction solvent was further processed by solid-phase extraction (SPE) clean-up using 96-Well Oasis® HLB Plates. Six SPE washing steps were applied to remove matrix compounds after which the growth promoters were eluted and analysed using UHPLC-MS/MS. To achieve lower detection levels and to reduce LC-solvent consumption, a narrow-bore column with an internal diameter of 1 mm was used, instead of the conventional 2.1 mm. During analysis, the mass spectrometer was operated in negative and positive ionisation mode (ion switching). The newly developed method was validated according to the Commission Decision 2002/657. The results demonstrate that the method meets the criteria as established in this Commission Decision. The precision of the method for exogenous steroids varies between 85 and 115%, the CCα for the compounds ranges from 0.1–0.9 μg kg−1 and the expanded measurement uncertainty was lower than 36%. Compared to our current in-house methods with analysis times of 2 days for a maximum of 24 samples, the new method offers improved sample throughput (96 samples in less than 24 h) and lower detection limits.
Global environmental change effects on plant community composition trajectories depend upon management legacies
Perring, Michael P. ; Bernhardt-Römermann, Markus ; Baeten, Lander ; Midolo, Gabriele ; Blondeel, Haben ; Depauw, Leen ; Landuyt, Dries ; Maes, Sybryn L. ; Lombaerde, Emiel De; Carón, Maria Mercedes ; Vellend, Mark ; Brunet, Jörg ; Chudomelová, Markéta ; Decocq, Guillaume ; Diekmann, Martin ; Dirnböck, Thomas ; Dörfler, Inken ; Durak, Tomasz ; Frenne, Pieter De; Gilliam, Frank S. ; Hédl, Radim ; Heinken, Thilo ; Hommel, Patrick ; Jaroszewicz, Bogdan ; Kirby, Keith J. ; Kopecký, Martin ; Lenoir, Jonathan ; Li, Daijiang ; Máliš, František ; Mitchell, Fraser J.G. ; Naaf, Tobias ; Newman, Miles ; Petřík, Petr ; Reczyńska, Kamila ; Schmidt, Wolfgang ; Standovár, Tibor ; Świerkosz, Krzysztof ; Calster, Hans Van; Vild, Ondřej ; Wagner, Eva Rosa ; Wulf, Monika ; Verheyen, Kris - \ 2018
Global Change Biology 24 (2018)4. - ISSN 1354-1013 - p. 1722 - 1740.
Biodiversity change - Climate change - Disturbance regime - ForestREplot - Herbaceous layer - Management intensity - Nitrogen deposition - Plant functional traits - Time lag - Vegetation resurvey
The contemporary state of functional traits and species richness in plant communities depends on legacy effects of past disturbances. Whether temporal responses of community properties to current environmental changes are altered by such legacies is, however, unknown. We expect global environmental changes to interact with land-use legacies given different community trajectories initiated by prior management, and subsequent responses to altered resources and conditions. We tested this expectation for species richness and functional traits using 1814 survey-resurvey plot pairs of understorey communities from 40 European temperate forest datasets, syntheses of management transitions since the year 1800, and a trait database. We also examined how plant community indicators of resources and conditions changed in response to management legacies and environmental change. Community trajectories were clearly influenced by interactions between management legacies from over 200 years ago and environmental change. Importantly, higher rates of nitrogen deposition led to increased species richness and plant height in forests managed less intensively in 1800 (i.e., high forests), and to decreases in forests with a more intensive historical management in 1800 (i.e., coppiced forests). There was evidence that these declines in community variables in formerly coppiced forests were ameliorated by increased rates of temperature change between surveys. Responses were generally apparent regardless of sites' contemporary management classifications, although sometimes the management transition itself, rather than historic or contemporary management types, better explained understorey responses. Main effects of environmental change were rare, although higher rates of precipitation change increased plant height, accompanied by increases in fertility indicator values. Analysis of indicator values suggested the importance of directly characterising resources and conditions to better understand legacy and environmental change effects. Accounting for legacies of past disturbance can reconcile contradictory literature results and appears crucial to anticipating future responses to global environmental change.
A review of human thermal comfort experiments in controlled and semi-controlled environments
Craenendonck, Stijn Van; Lauriks, Leen ; Vuye, Cedric ; Kampen, Jarl - \ 2018
Renewable and Sustainable Energy Reviews 82 (2018). - ISSN 1364-0321 - p. 3365 - 3378.
Climate chamber - Experiment - Methodology - Questionnaire - Survey - Thermal comfort
There are three main methods to improve thermal comfort in existing buildings: modeling, experiments and measurements. Regarding experiments, no standardized procedure exists. This article provides an answer to the question: “What is the most common practice for human thermal comfort experiments in (semi-)controlled environments?”. A total of 166 articles presenting results on 206 experiments were collected and analyzed to extrapolate the most common practice. The results are arranged in five main themes: subjects (e.g. number and age), climate chamber (e.g. surface area), thermal environment, experimental procedure (e.g. phases and duration), and questionnaire. A typical experiment was found to employ 25 subjects and to take place in a permanent climate chamber with a floor area of 24 m2 During the experiment, 3 air temperature variations are used. The test itself takes 115 min, but is preceded by a preconditioning and conditioning phase. The subject is given a questionnaire at regular intervals of 15 min, with questions highly dependent on topic, but including thermal sensation and comfort vote rated on a bipolar 7-level scale. Number of subjects, gender distribution, type and floor area of the climate chamber and utilization rate of the scale for rating thermal comfort and sensation are all linked to topic, as well as number of different air temperatures, whether conditioning is employed and questions in the questionnaire. Several links between experiment characteristics reciprocally are also identified.
Edith Lammerts van Bueren neemt afscheid: van docent biologische teelt naar hoogleraar veredeling
Lammerts van Bueren, Edith - \ 2017
Non-targeted workflow for identification of antimicrobial compounds in animal feed using bioassay-directed screening in combination with liquid chromatography-high resolution mass spectrometry
Wegh, Robin S. ; Berendsen, Bjorn J.A. ; Driessen-Van Lankveld, Wilma D.M. ; Pikkemaat, Mariël G. ; Zuidema, Tina ; Ginkel, Leen A. Van - \ 2017
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 34 (2017)11. - ISSN 1944-0049 - p. 1935 - 1947.
animal feed - antibiotics - Antimicrobials - bioassay - LC-MS
A non-targeted workflow is reported for the isolation and identification of antimicrobial active compounds using bioassay-directed screening and LC coupled to high-resolution MS. Suspect samples are extracted using a generic protocol and fractionated using two different LC conditions (A and B). The behaviour of the bioactive compound under these different conditions yields information about the physicochemical properties of the compound and introduces variations in co-eluting compounds in the fractions, which is essential for peak picking and identification. The fractions containing the active compound(s) obtained with conditions A and B are selected using a microbiological effect-based bioassay. The selected bioactive fractions from A and B are analysed using LC combined with high-resolution MS. Selection of relevant signals is automatically carried out by selecting all signals present in both bioactive fractions A and B, yielding tremendous data reduction. The method was assessed using two spiked feed samples and subsequently applied to two feed samples containing an unidentified compound showing microbial growth inhibition. In all cases, the identity of the compound causing microbiological inhibition was successfully confirmed.
Evaluation of a loop-mediated isothermal amplification (LAMP) method for rapid on-site detection of horse meat
Aartse, Aafke ; Scholtens-Toma, Ingrid ; A, Hans J.G. van der; Boersma-Greve, Monique M. ; Prins, Theo W. ; Ginkel, Leen A. van; Kok, Esther J. ; Bovee, Toine F.H. - \ 2017
Food Control 81 (2017). - ISSN 0956-7135 - p. 9 - 15.
Horse meat - Loop-mediated isothermal amplification (LAMP) - On-site detection - qPCR - Rapid method

Detection of horse DNA by loop-mediated isothermal amplification (LAMP) seems one of the most promising methods to meet the criteria of fast, robust, cost efficient, specific, and sensitive on-site detection. In the present study an assessment of the specificity and sensitivity of the LAMP horse screening assay was made and outcomes were compared with the EURL-AP (European Union Reference laboratory for Animal Proteins in feeding stuffs) qPCR method. The specificity was tested with DNA samples from seven other species. The sensitivity of the LAMP assay was subsequently challenged with different percentages of horse DNA in cattle DNA and different percentages of horse meat in cattle meat. Both qPCR and LAMP were able to reliably detect horse DNA or meat below 0.1%, but LAMP was able to do so in less than 30 min. The DNA of other species did not result in a response in the LAMP horse assay. These features show that the LAMP method is fast, specific, and sensitive. Next, 69 processed meat samples were screened for the presence of horse DNA. The results showed that the LAMP horse assay, combined with a simple and fast on-site DNA extraction method, results in similar outcomes as the EURL-AP qPCR method and is thus a promising screening assay to be used outside the laboratory. Only samples that are screened on-site as suspect in the LAMP horse assay, need to be brought to the laboratory for confirmation with the more laborious EURL-AP qPCR reference method.

Hypothermic perfusion with retrograde outflow during right hepatectomy is safe and feasible
Reiniers, Megan J. ; Olthof, Pim B. ; Golen, Rowan F. van; Heger, Michal ; Beek, Adriaan A. van; Meijer, Ben ; Leen, René ; Kuilenburg, André B.P. van; Mearadji, Banafsche ; Bennink, Roelof J. ; Verheij, Joanne ; Gulik, Thomas M. van - \ 2017
Surgery 162 (2017)1. - ISSN 0039-6060 - p. 48 - 58.

Background: In situ hypothermic perfusion during liver resection performed under vascular inflow occlusion decreases hepatic ischemia-reperfusion injury, but technical limitations have restricted its widespread use. In situ hypothermic perfusion with retrograde outflow circumvents these impediments and thus could extend the applicability of in situ hypothermic perfusion. The safety and feasibility of in situ hypothermic perfusion with retrograde outflow were analyzed in selected patients undergoing right (extended) hepatectomy and compared to intermittent vascular inflow occlusion, the gold standard method, in this randomized pilot study. Methods: Patients were first screened for parenchymal liver disease (exclusion criteria: steatosis ≥30%, cirrhosis, or cholestasis). Study participants were randomized intraoperatively to undergo in situ hypothermic perfusion with retrograde outflow (n = 9) or intermittent vascular inflow occlusion (n = 9). The target liver core temperature during in situ hypothermic perfusion with retrograde outflow was 28°C. The primary end point was ischemia-reperfusion injury (expressed by peak postoperative transaminase levels). Secondary outcomes included functional liver regeneration (assessed by hepatobiliary scintigraphy) and clinical outcomes. Results: Peak transaminase levels, total bilirubin, and the international normalized ratio were similar between both groups, although a trend toward more rapid normalization of bilirubin levels was noted for the in situ hypothermic perfusion with retrograde outflow group. Functional liver regeneration as evaluated by hepatobiliary scintigraphy was improved on postoperative day 3 following in situ hypothermic perfusion with retrograde outflow but not after intermittent vascular inflow occlusion. Furthermore, in situ hypothermic perfusion with retrograde outflow (requiring continuous ischemia) was comparable to intermittent vascular inflow occlusion for all clinical outcomes, including postoperative complications and hospital stay. Conclusion: The use of in situ hypothermic perfusion with retrograde outflow appears to be safe and feasible in selected patients with healthy liver parenchyma and may benefit early functional liver regeneration. Future applications of in situ hypothermic perfusion with retrograde outflow include patients with damaged liver parenchyma who would require major hepatic resection with a prolonged vascular inflow occlusion duration.

Teeltrecepten voor nieuwe rassen
Balen, Derk van - \ 2017
A global inter-laboratory study to assess acquisition modes for multi-compound confirmatory analysis of veterinary drugs using liquid chromatography coupled to triple quadrupole, time of flight and orbitrap mass spectrometry
Berendsen, Bjorn J.A. ; Meijer, Thijs ; Mol, Hans G.J. ; Ginkel, Leen van; Nielen, Michel W.F. - \ 2017
Analytica Chimica Acta 962 (2017). - ISSN 0003-2670 - p. 60 - 72.
Inter-laboratory study - Liquid chromatography - Mass spectrometry - Performance criteria - Veterinary drugs residue analysis

According to EU legislation a confirmatory method used for residue analysis should be able to confirm the identity of a compound beyond reasonable doubt. To provide an adequate instrumental set-up, Commission Decision 2002/657/EC introduced the concept of "identification points". A second aspect to assure unequivocal confirmation, is the establishment of ion ratio and retention time criteria. Currently, the gold standard for confirmatory analysis of most veterinary drug residues is liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) in selected reaction monitoring (SRM) acquisition mode, isolating one precursor ion and monitoring two a priori selected product ions, yielding 4 identification points. We comprehensively evaluated the use of different low and high resolution LC-MS(/MS) techniques and acquisition modes with respect to the selectivity of 100 veterinary drugs in liver, muscle and urine extracts aiming to critically review the currently established identification points system. A comparison among MS/MS in SRM mode with high resolution mass spectrometry (HRMS) in full scan, all ion fragmentation and targeted MS/MS was made based on a unique inter-laboratory study, which comprises 21 laboratories from four different continents and equipment from all major vendors.In total 186 samples were analysed yielding results for 9282 analyte/matrix combinations. It was observed that the false positive rate approximately doubles if no ion ratio criterion is applied indicating that this criterion is important to prevent false positive results. Full scan HRMS analysis, only monitoring the molecular ion and allowing a ±5 ppm mass tolerance is, in general, less selective than low resolution MS/MS using SRM, and thus full scan alone is considered not sufficient for confirmatory analysis. Furthermore, even though the number of data on all ion fragmentation and targeted MS/MS at high resolution was limited, based on the data obtained, it was observed that the acquisition mode as well as the mass resolution needed, very much depend on the matrix and the compound itself. For complex matrix extracts and non-selective compounds (worst-case situation), only targeted MS/MS, monitoring the precursor ion and a single product ion in HR-MS using a maximum of ±5 ppm mass deviation, leads to comparable selectivity and false positive and negative rate as SRM monitoring two product ions in LR-MS. We conclude that the currently applied identification point system as established in commission decision 2002/657/EC should be revised with respect to the allocation of identification points.

World Register of marine Cave Species (WoRCS): a new Thematic Species Database for marine and anchialine cave biodiversity
Gerovasileiou, Vasilis ; Martínez, Alejandro ; Álvarez, Fernando ; Boxshall, Geoff ; Humphreys, William F. ; Jaume, Damià ; Becking, L.E. ; Muricy, Guilherme ; Hengstum, Peter J. van; Dekeyzer, Stefanie ; Decock, Wim ; Vanhoorne, Bart ; Vandepitte, Leen ; Bailly, Nicolas ; Iliffe, Thomas M. - \ 2016
Research Ideas and Outcomes 2 (2016).
Marine caves - anchialine ecosystems - biodiversity - global species databases - biodiversity management
Scientific exploration of marine cave environments and anchialine ecosystems over recent decades has led to outstanding discoveries of novel taxa, increasing our knowledge of biodiversity. However, biological research on underwater caves has taken place only in a few areas of the world and relevant information remains fragmented in isolated publications and databases. This fragmentation makes assessing the conservation status of marine cave species especially problematic, and this issue should be addressed urgently given the stresses resulting from planned and rampant development in the coastal zone worldwide. The goal of the World Register of marine Cave Species (WoRCS) initiative is to create a comprehensive taxonomic and ecological database of known species from marine caves and anchialine systems worldwide and to present this as a Thematic Species Database (TSD) of the World Register of marine Species (WoRMS). WoRCS will incorporate ecological data (e.g., type of environment, salinity regimes, and cave zone) as well as geographical information on the distribution of species in cave and anchialine environments. Biodiversity data will be progressively assembled from individual database sources at regional, national or local levels, as well as from literature sources (estimate: >20,000 existing records of cave-dwelling species scattered in several databases). Information will be organized in the WoRCS database following a standard glossary based on existing terminology. Cave-related information will be managed by the WoRCS thematic editors with all data dynamically linked to WoRMS and its team of taxonomic editors. In order to mobilize data into global biogeographic databases, a Gazetteer of the Marine and Anchialine Caves of the World will be established. The presence records of species could be eventually georeferenced for submission to the Ocean Biogeographic Information System (OBIS) and constitute an important dataset for biogeographical and climate change studies on marine caves and anchialine systems
Sex hormone-binding globulin regulation of androgen bioactivity in vivo : Validation of the free hormone hypothesis
Laurent, Michaël R. ; Hammond, Geoffrey L. ; Blokland, Marco ; Jardí, Ferran ; Antonio, Leen ; Dubois, Vanessa ; Khalil, Rougin ; Sterk, Saskia S. ; Gielen, Evelien ; Decallonne, Brigitte ; Carmeliet, Geert ; Kaufman, Jean Marc ; Fiers, Tom ; Huhtaniemi, Ilpo T. ; Vanderschueren, Dirk ; Claessens, Frank - \ 2016
Scientific Reports 6 (2016). - ISSN 2045-2322

Sex hormone-binding globulin (SHBG) is the high-affinity binding protein for androgens and estrogens. According to the free hormone hypothesis, SHBG modulates the bioactivity of sex steroids by limiting their diffusion into target tissues. Still, the in vivo physiological role of circulating SHBG remains unclear, especially since mice and rats lack circulating SHBG post-natally. To test the free hormone hypothesis in vivo, we examined total and free sex steroid concentrations and bioactivity on target organs in mice expressing a human SHBG transgene. SHBG increased total androgen and estrogen concentrations via hypothalamic-pituitary feedback regulation and prolonged ligand half-life. Despite markedly raised total sex steroid concentrations, free testosterone was unaffected while sex steroid bioactivity on male and female reproductive organs was attenuated. This occurred via a ligand-dependent, genotype-independent mechanism according to in vitro seminal vesicle organ cultures. These results provide compelling support for the determination of free or bioavailable sex steroid concentrations in medicine, and clarify important comparative differences between translational mouse models and human endocrinology.

Snelle opschaling resistente aardappelrassen beproefd
Balen, Derk van; Rijk, Joost - \ 2016
A critical assessment of the performance criteria in confirmatory analysis for veterinary drug residue analysis using mass spectrometric detection in selected reaction monitoring mode
Berendsen, Bjorn J.A. ; Meijer, Thijs ; Wegh, Robin ; Mol, Hans G.J. ; Smyth, Wesley G. ; Armstrong Hewitt, S. ; Ginkel, Leen van; Nielen, Michel W.F. - \ 2016
Drug Testing and Analysis 8 (2016)5-6. - ISSN 1942-7603 - p. 477 - 490.
confirmatory analysis - ion ratio - liquid chromatography - mass spectrometry - performance criteria

Besides the identification point system to assure adequate set-up of instrumentation, European Commission Decision 2002/657/EC includes performance criteria regarding relative ion abundances in mass spectrometry and chromatographic retention time. In confirmatory analysis, the relative abundance of two product ions, acquired in selected reaction monitoring mode, the ion ratio should be within certain ranges for confirmation of the identity of a substance. The acceptable tolerance of the ion ratio varies with the relative abundance of the two product ions and for retention time, CD 2002/657/EC allows a tolerance of 5%. Because of rapid technical advances in analytical instruments and new approaches applied in the field of contaminant testing in food products (multi-compound and multi-class methods) a critical assessment of these criteria is justified. In this study a large number of representative, though challenging sample extracts were prepared, including muscle, urine, milk and liver, spiked with 100 registered and banned veterinary drugs at levels ranging from 0.5 to 100 µg/kg. These extracts were analysed using SRM mode using different chromatographic conditions and mass spectrometers from different vendors. In the initial study, robust data was collected using four different instrumental set-ups. Based on a unique and highly relevant data set, consisting of over 39 000 data points, the ion ratio and retention time criteria for applicability in confirmatory analysis were assessed. The outcomes were verified based on a collaborative trial including laboratories from all over the world. It was concluded that the ion ratio deviation is not related to the value of the ion ratio, but rather to the intensity of the lowest product ion. Therefore a fixed ion ratio deviation tolerance of 50% (relative) is proposed, which also is applicable for compounds present at sub-ppb levels or having poor ionisation efficiency. Furthermore, it was observed that retention time shifts, when using gradient elution, as is common practice nowadays, are mainly observed for early eluting compounds. Therefore a maximum retention time deviation of 0.2 min (absolute) is proposed. These findings should serve as input for discussions on the revision of currently applied criteria and the establishment of a new, globally accepted, criterion document for confirmatory analysis.

4th International Conference on Food Oral Processing
Sturtewagen, Leen - \ 2016
Does swallowing resemble a phase transition?
Meer vruchten uit de bodem
Wijk, Kees van - \ 2016
Insecten in dood hout
Moraal, Leen - \ 2014
Plaaginsecten
Moraal, Leen - \ 2014
Lezing voor de Nationale Bomenbank
Moraal, Leen - \ 2014
Lezing voor de Nationale Bomenbank
Moraal, Leen - \ 2014
Lezing voor de Nationale Bomenbank
Moraal, Leen - \ 2014
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.