Staff Publications

Staff Publications

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    '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.

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    Advancements in effect-based surface water quality assessment
    Baat, M.L. De; Oost, R. Van der; Lee, G.H. Van der; Wieringa, N. ; Hamers, T. ; Verdonschot, P.F.M. ; Voogt, P. De; Kraak, M.H.S. - \ 2020
    Water Research 183 (2020). - ISSN 0043-1354
    Agriculture - Bioassay battery - Micropollutants - Passive sampling - Wastewater - Water quality monitoring

    Legally-prescribed chemical monitoring is unfit for determining the pollution status of surface waters, and there is a need for improved assessment methods that consider the aggregated risk of all bioavailable micropollutants present in the aquatic environment. Therefore, the present study aimed to advance effect-based water quality assessment by implementing methodological improvements and to gain insight into contamination source-specific bioanalytical responses. Passive sampling of non-polar and polar organic compounds and metals was applied at 14 surface water locations that were characterized by two major anthropogenic contamination sources, agriculture and wastewater treatment plant (WWTP) effluent, as well as reference locations with a low expected impact from micropollutants. Departing from the experience gained in previous studies, a battery of 20 in vivo and in vitro bioassays was composed and subsequently exposed to the passive sampler extracts. Next, the bioanalytical responses were divided by their respective effect-based trigger values to obtain effect-based risk quotients, which were summed per location. These cumulative ecotoxicological risks were lowest for reference locations (4.3–10.9), followed by agriculture locations (11.3–27.2) and the highest for WWTP locations (12.8–47.7), and were mainly driven by polar organic contaminants. The bioanalytical assessment of the joint risks of metals and (non-)polar organic compounds resulted in the successful identification of pollution source-specific ecotoxicological risk profiles: none of the bioassays were significantly associated with reference locations nor with multiple location types, while horticulture locations were significantly characterized by anti-AR and anti-PR activity and cytotoxicity, and WWTP sites by ERα activity and toxicity in the in vivo bioassays. It is concluded that the presently employed advanced effect-based methods can readily be applied in surface water quality assessment and that the integration of chemical- and effect-based monitoring approaches will foster future-proof water quality assessment strategies on the road to a non-toxic environment.

    Innovative lateral flow devices for the detection of pesticides harmful to bees
    Xu, Mang ; Hoof, R.A. van; Hamers, A.R.M. ; Rijk, T.C. de; Guo, Yirong ; Bovee, T.F.H. ; Peters, J. - \ 2019
    Conventional instrumental detection of pesticides is complex and time-consuming, and is not realistic at the Point Of Need. In the B-GOOD project, we applied a dual channel lateral flow device (LFD) that is able to detect six out of eight neonicotinoids based on monoclonal antibody interaction and found that these LFDs have strong potential for field application. Additionally, WFSR has developed a LFD prototype that detects fipronil, a pesticide which was responsible for the recent death of hundred-thousands of honey bees in the Netherlands. Other LFDs, for the detection of bee-harming pesticides are also under development. In the near future, B-GOOD is interested in applying the developed LFDs at the point of need.
    An outpatient nursing nutritional intervention to prehabilitate undernourished patients planned for surgery : A multicentre, cluster-randomised pilot study
    Noort, Harm H.J. van; Witteman, Ben J.M. ; Vermeulen, Hester ; Huisman-de Waal, Getty ; Hamers, J.P.H. - \ 2019
    Clinical Nutrition 39 (2019)8. - ISSN 0261-5614 - p. 2420 - 2427.
    Essential care - Nursing care - Nutritional support - Prehabilitation - Preoperative care - Undernutrition

    Background & aims: To improve the nutritional status of surgical patients before hospital admission, an Outpatient Nursing Nutritional Intervention (ONNI) was developed. The ONNI comprehends five components: determining causes of undernutrition, performing a nutritional care plan including tailored and general advice, self-monitoring of nutritional intake and eating patterns, counselling and encouragement, and conducting a follow-up telephone call to discuss improvements in nutritional behaviour. Here, we evaluate the feasibility and effectiveness of the ONNI. Methods: In a multi-centred, cluster-randomised pilot study, nurses from outpatient clinics were randomly allocated to usual care (UC) or the ONNI. Patients planned for elective surgery were included if they were at increased risk for undernutrition based on the Malnutrition Universal Screening Tool (MUST) and hospital admission was not planned within seven days. Feasibility outcomes included participation rate, extent of intervention delivery, and patient satisfaction. Nutritional intake was monitored for two days before admission. Body weight, BMI and MUST scores at hospital admission were compared to measurements from the outpatient clinic visit. Data were analysed on an intention-to-treat basis by researchers who were blinded for patients and caregivers. Results: Forty-eight patients enrolled the feasibility phase. Participation rate was 72%. Nurses delivered all intervention components adequately in the end of the implementation period. Finally, 152 patients (IG: n = 66, 43%) participated in the study. A significant difference in mean energy intake (870 kcal/d, 95%CI:630-1109 p < 0.000) and mean protein intake (34.1 g/d, 95%CI: 25.0–43.2; p < 0.000) was observed in favour of the IG. Nutritional energy requirements were achieved in 74% (n = 46) of the IG and in 17% (n = 13) of the UC group (p < 0.000), and protein requirements were achieved in 52% (n = 32) of the IG, compared to 8% (n = 6) of the UC group (p < 0.000). Body weight, BMI and MUST scores did not change in either group. Conclusions: The ONNI is a feasible and effective intervention tool for nurses at outpatient clinics. Patients in the IG had more nutritional intake and fulfilled nutritional requirements significantly more often than patients receiving UC. Further research is required to determine the optimal pre-operative timing of nutritional support and to measure its effect on other patients groups. Clinical trial registration: The study protocol was registered at the website with the following identifier: NCT02440165.

    BPA, BADGE and analogues : A new multi-analyte LC-ESI-MS/MS method for their determination and their in vitro (anti)estrogenic and (anti)androgenic properties
    Leeuwen, Stefan P.J. van; Bovee, Toine F.H. ; Awchi, Mohamad ; Klijnstra, Mirjam D. ; Hamers, Astrid R.M. ; Hoogenboom, Ron L.A.P. ; Portier, Liza ; Gerssen, Arjen - \ 2019
    Chemosphere 221 (2019). - ISSN 0045-6535 - p. 246 - 253.
    Androgenic - BADGE - BP-analogues - BPA - Estrogenic - In vitro - LC-MS/MS - Multimethod

    Information on the occurrence and endocrine potencies of analogues of bisphenol A (BPA) and diglycidyl ester derivatives (BDGEs) of BPA and BPF is limited. Such information is, however, important as the current debate on BPA and the lowered BPA migration limit in Europe may provide an incentive for application of structural analogues. A new sensitive multi-analyte LC-ESI-MS/MS method was developed to measure 17 bisphenols (BPs) and 6 BDGEs in food, beverages and drinkware. Yeast based bioassays were used to determine the in vitro (anti)estrogenic and (anti)androgenic properties of these and 7 additional BPs and BDGEs. Drinkware of polycarbonate and other materials were analysed for BPs and BDGEs. Only BPA and BPS and both at trace levels were found in a few containers. A limited number of (canned) foods and beverages were also analysed. BPA was the most frequently detected BP (ranged from 0.03 ng mL−1 in a beverage sample to 68 ng g−1 in food). Other BPs detected were BPS, 2,2-BPF and 4,4-BPF. In addition BADGE, BADGE.HCl, BADGE.H2O and BADGE.2H2O were detected from 0.08 ng mL−1 in a beverage sample to 3.3 ng g−1 in food. In vitro testing showed that most BPs exhibited an equal or higher estrogenic potency than BPA and most of them also showed a higher anti-androgenic potency, i.e. BPB, BPCl, BPC, BPE, 4,4-BPF, BPP, BPAF, and BPTMC. Some BPs and BDGEs were not estrogenic, but showed an anti-estrogenic effect and were anti-androgenic too. BPS was only weakly estrogenic and BADGE.2H2O and BFDGE.2H2O showed no in vitro activity. The present data show that in addition to BPA, other BPs and BDGEs can be present in food and drinks, some displaying in vitro endocrine activities.

    Phenolic compounds of Triplaris gardneriana can protect cells against oxidative stress and restore oxidative balance
    Almeida, Thiago Silva de; Neto, José Joaquim Lopes ; Sousa, Nathanna Mateus de; Pessoa, Igor Parra ; Vieira, Leonardo Rogério ; Medeiros, Jackeline Lima De; Boligon, Aline Augusti ; Hamers, Astrid R.M. ; Farias, Davi Felipe ; Peijnenburg, Ad ; Carvalho, Ana Fontenele Urano - \ 2017
    Biomedicine and Pharmacotherapy 93 (2017). - ISSN 0753-3322 - p. 1261 - 1268.
    Cell imaging - DPPH - MCF-7 cells - Medicinal plant - TBARS
    This work aimed to add value to an underexploited plant species from Brazil, Triplaris gardneriana. To that, the phenolic compounds profile of its seed ethanolic extract and fractions was examined by HPLC and the antioxidant capacity assessed using chemical assays as well as in vitro cell imaging. Twelve compounds were quantified and classified as either phenolic acids or flavonoids. The fractionation process did not generate fractions with different compositions except for chloroformic fraction, which showed only 6 out of 12 standard compounds used. DPPH assay revealed samples with a concentration-dependent radical scavenging activity, being methanolic fraction the one with the largest activity (SC50 11.45 ± 0.02 μg/mL). Lipid peroxidation assessment, in the presence and absence of stress inducer, showed that particularly the ethanol extract (IC50 26.75 ± 0.08 μg/mL) and the ethyl acetate fraction (IC50 6.14 ± 0.03 μg/mL) could inhibit lipid peroxidation. The ethyl acetate fraction performed best in chelating iron (48% complexation at 1000 μg/mL). Cell imaging experiments showed that the ethanolic extract could protect cells against oxidative stress as well as restore the oxidative balance upon stress induction. In conclusion, T. gardneriana seeds showed a promising phenolic compounds profile and antioxidant activity that may be further exploited.
    Visualization of BRI1 and SERK3/BAK1 nanoclusters in Arabidopsis roots
    Hutten, Stefan J. ; Hamers, Danny S. ; Toorn, Marije Aan Den; Esse, Wilma Van; Nolles, Antsje ; Bücherl, Christoph A. ; Vries, Sacco C. De; Hohlbein, Johannes ; Borst, Janwillem - \ 2017
    PLoS ONE 12 (2017)1. - ISSN 1932-6203
    Brassinosteroids (BRs) are plant hormones that are perceived at the plasma membrane (PM) by the ligand binding receptor BRASSINOSTEROID-INSENSITIVE1 (BRI1) and the co-receptor SOMATIC EMBRYOGENESIS RECEPTOR LIKE KINASE 3/BRI1 ASSOCIATED KINASE 1 (SERK3/BAK1). To visualize BRI1-GFP and SERK3/BAK1-mCherry in the plane of the PM, variable-angle epifluorescence microscopy (VAEM) was employed, which allows selective illumination of a thin surface layer. VAEM revealed an inhomogeneous distribution of BRI1-GFP and SERK3/BAK1-mCherry at the PM, which we attribute to the presence of distinct nanoclusters. Neither the BRI1 northeSERK3/BAK1 nanocluster density is affected by depletion of endogenous ligands or application of exogenous ligands. To reveal interacting populations of receptor complexes, we utilized selective-surface observation-fluorescence lifetime imaging microscopy (SSO-FLIM) for the detection of Forster resonance energy transfer (FRET). Using this approach, we observed hetero-oligomerisation of BRI1 and SERK3 in the nanoclusters, which did not change upon depletion of endogenous ligand or signal activation. Upon ligand application, however, the number of BRI1-SERK3/BAK1 hetero-oligomers was reduced, possibly due to endocytosis of active signalling units of BRI1-SERK3/BAK1 residing in the PM. We propose that formation of nanoclusters in the plant PM is subjected to biophysical restraints, while the stoichiometry of receptors inside these nanoclusters is variable and important for signal transduction.
    Effects of digested onion extracts on intestinal gene expression using rat intestine slices
    Wit, N.J.W. de; Hulst, M.M. ; Govers, C.C.F.M. ; Meulen, J. van der; Hoef, A.M.A. van; Stoopen, G.M. ; Hamers, A.R.M. ; Hoekman, A.J.W. ; Vos, C.H. de; Bovee, T.F.H. ; Smits, M.A. ; Mes, J.J. ; Hendriksen, P.J.M. - \ 2016
    Rattus norvegicus - GSE84179 - PRJNA328225
    Rat small intestine precision cut slices were exposed for 6 hours to in vitro digested yellow (YOd) and white onion extracts (WOd) that was followed by transcriptomics analysis. The digestion was performed to mimic the digestion that in vivo takes place in the stomach and small intestine. The transcriptomics response of the rat small intestine precision cut slices was compared to that of human Caco-2 cells and the pig in-situ small intestinal segment perfusion. The microarray data for the human Caco-2 cells (GSE83893) and the pig in-situ small intestinal segment perfusion (GSE83908) have been submitted separately from the current data on rat intestine. The goal was to obtain more insight into to which extent mode of actions depend on the experimental model. A main outcome was that each of the three models pointed to the same mode of action: induction of oxidative stress and particularly the Keap1-Nrf2 pathway.
    Effects of digested onion extracts on intestinal gene expression: an interspecies comparison using different intestine models
    Wit, N.J.W. de; Hulst, M.M. ; Govers, C.C.F.M. ; Meulen, J. van der; Hoef, A.M.A. van; Stoopen, G.M. ; Hamers, A.R.M. ; Hoekman, A.J.W. ; Vos, C.H. de; Bovee, T.F.H. ; Smits, M.A. ; Mes, J.J. ; Hendriksen, P.J.M. - \ 2016
    PLoS ONE 11 (2016)9. - ISSN 1932-6203 - 18 p.
    Human intestinal tissue samples are barely accessible to study potential health benefits of nutritional compounds. Numbers of animals used in animal trials, however, need to be minimalized. Therefore, we explored the applicability of in vitro (human Caco-2 cells) and ex vivo intestine models (rat precision cut intestine slices and the pig in-situ small intestinal segment perfusion (SISP) technique) to study the effect of food compounds. In vitro digested yellow (YOd) and white onion extracts (WOd) were used as model food compounds and transcriptomics was applied to obtain more insight into which extent mode of actions depend on the model. The three intestine models shared 9,140 genes which were used to compare the responses to digested onions between the models. Unsupervised clustering analysis showed that genes up- or down-regulated by WOd in human Caco-2 cells and rat intestine slices were similarly regulated by YOd, indicating comparable modes of action for the two onion species. Highly variable responses to onion were found in the pig SISP model. By focussing only on genes with significant differential expression, in combination with a fold change > 1.5, 15 genes showed similar onion-induced expression in human Caco-2 cells and rat intestine slices and 2 overlapping genes were found between the human Caco-2 and pig SISP model. Pathway analyses revealed that mainly processes related to oxidative stress, and especially the Keap1-Nrf2 pathway, were affected by onions in all three models. Our data fit with previous in vivo studies showing that the beneficial effects of onions are mostly linked to their antioxidant properties. Taken together, our data indicate that each of the in vitro and ex vivo intestine models used in this study, taking into account their limitations, can be used to determine modes of action of nutritional compounds and can thereby reduce the number of animals used in conventional nutritional intervention studies.
    Muscle-specific inflammation induced by MCP-1 overexpression does not affect whole-body insulin sensitivity in mice
    Evers-van Gogh, Inkie J.A. ; Oteng, Antwi Boasiako ; Alex, Sheril ; Hamers, Nicole ; Catoire, Milene ; Stienstra, Rinke ; Kalkhoven, Eric ; Kersten, Sander - \ 2016
    Diabetologia 59 (2016)3. - ISSN 0012-186X - p. 624 - 633.
    Inflammation - Insulin resistance - MCP-1 - Muscle-specific - Myokine - Obesity - Type 2 diabetes

    Aims/hypothesis: Obesity is associated with a state of chronic low-grade inflammation that is believed to contribute to the development of skeletal muscle insulin resistance. However, the extent to which local and systemic elevation of cytokines, such as monocyte chemoattractant protein 1 (MCP-1), interferes with the action of insulin and promotes insulin resistance and glucose intolerance in muscle remains unclear. Here, we aim to investigate the effect of muscle-specific overexpression of MCP-1 on insulin sensitivity and glucose tolerance in lean and obese mice. Methods: We used Mck–Mcp-1 transgenic (Tg) mice characterised by muscle-specific overexpression of Mcp-1 (also known as Ccl2) and elevated plasma MCP-1 levels. Mice were fed either chow or high-fat diet for 10 weeks. Numerous metabolic variables were measured, including glucose and insulin tolerance tests, muscle insulin signalling and plasma NEFA, triacylglycerol, cholesterol, glucose and insulin. Results: Despite clearly promoting skeletal muscle inflammation, muscle-specific overexpression of Mcp-1 did not influence glucose tolerance or insulin sensitivity in either lean chow-fed or diet-induced obese mice. In addition, plasma NEFA, triacylglycerol, cholesterol, glucose and insulin were not affected by MCP-1 overexpression. Finally, in vivo insulin-induced Akt phosphorylation in skeletal muscle did not differ between Mcp-1-Tg and wild-type mice. Conclusions/interpretation: We show that increased MCP-1 production in skeletal muscle and concomitant elevated MCP-1 levels in plasma promote inflammation in skeletal muscle but do not influence insulin signalling and have no effect on insulin resistance and glucose tolerance in lean and obese mice. Overall, our data argue against MCP-1 promoting insulin resistance in skeletal muscle and raise questions about the impact of inflammation on insulin sensitivity in muscle.

    Glyceollins and dehydroglyceollins isolated from soybean act as SERMs and ER subtype-selective phytoestrogens
    De Schans, Milou G.M. Van; Vincken, Jean Paul ; Waard, Pieter De; Hamers, Astrid R.M. ; Bovee, Toine F.H. ; Gruppen, Harry - \ 2016
    Journal of Steroid Biochemistry and Molecular Biology 156 (2016). - ISSN 0960-0760 - p. 53 - 63.
    6a,11a-Pterocarpene - 6a-Hydroxy-pterocarpan - hER yeast bioassay - hERα-CALUX - Molar extinction coefficient - Prenylation

    Seven prenylated 6a-hydroxy-pterocapans and five prenylated 6a,11a-pterocarpenes with different kinds of prenylation were purified from an ethanolic extract of fungus-treated soybean sprouts. The activity of these compounds toward both human estrogen receptors (hERα and hERβ) was determined in a yeast bioassay and the activity toward hERα was additionally tested in an U2-OS based hERα CALUX bioassay. In the yeast bioassay, compounds with chain prenylation showed in general an agonistic mode of action toward hERα, whereas furan and pyran prenylation led to an antagonistic mode of action. Five of these antagonistic compounds had an agonistic mode of action in the U2-OS based hERα CALUX bioassay, implying that these compounds can act as SERMs. The yeast bioassay also identified 8 ER subtype-selective compounds, with either an antagonistic mode of action or no response toward hERα and an agonistic mode of action toward hERβ. The ER subtype-selective compounds were characterized by 6a-hydroxy-pterocarpan or 6a,11a-pterocarpene backbone structure. It is suggested that either the extra D-ring or the increase in length to 12-13.5 Å of these compounds is responsible for an agonistic mode of action toward hERβ and, thereby, inducing ER subtype-selective behavior.

    Programming of metabolic effects in C57BL/6JxFVB mice by exposure to bisphenol A during gestation and lactation
    Esterik, J.C.J. Van; Dollé, M.E.T. ; Lamoree, M.H. ; Leeuwen, S.P.J. van; Hamers, T. ; Legler, J. ; Ven, L.T.M. Van der - \ 2014
    Toxicology 321 (2014)1. - ISSN 0300-483X - p. 40 - 52.
    Bisphenol A - Developmental programming - Early life exposure - Endocrine disrupting compounds - Metabolic impairment - Obesogen

    The global rise in prevalence of obesity is not fully explained by genetics or life style factors. The developmental origins of health and disease paradigm suggests that environmental factors during early life could play a role. In this perspective, perinatal exposure to bisphenol A (BPA) has been indicated as a programming factor for obesity and related metabolic disorders later in life. Here we study early life programming by BPA using an experimental design that is relevant for human exposure. C57BL/6JxFVB hybrid mice were exposed during gestation and lactation via maternal feed to 8 non-toxic doses (0-3000. μg/kg body weight/day (μg/kg bw/d)) of BPA. After weaning, offspring were followed for 20 weeks without further exposure. Adult male offspring showed dose-dependent increases of body and liver weights, no effects on fat pad weights and a dose-dependent decrease in circulating glucagon. Female offspring showed a dose-dependent decrease in body weight, liver, muscle and fat pad weights, adipocyte size, serum lipids, serum leptin and adiponectin. Physical activity was decreased in exposed males and suggested to be increased in exposed females. Brown adipose tissue showed slightly increased lipid accumulation in males and lipid depletion in females, and ucp1 expression was dose-dependently increased in females. The effects in females were more reliable and robust than in males due to wide confidence intervals and potential confounding by litter size for male data. The lowest derived BMDL (lower bound of the (two-sided) 90%-confidence interval for the benchmark dose) of 233. μg/kg bw/d (for interscapular weight in females) was below the proposed BMDL of 3633. μg/kg bw/d as a basis for tolerable daily intake. Although these results suggest that BPA can program for an altered metabolic phenotype, the sexual dimorphism of effects and diversity of outcomes among studies similar in design as the present study do not mark BPA as a specific obesogen. The consistency within the complex of observed metabolic effects suggests that upstream key element(s) in energy homeostasis are modified. Sex-dependent factors contribute to the final phenotypic outcome.

    Development of FRET biosensors for mammalian and plant systems
    Hamers, D.S. ; Voorst Vader, L. van; Borst, J.W. ; Goedhart, J. - \ 2014
    Protoplasma 251 (2014)2. - ISSN 0033-183X - p. 333 - 347.
    yellow fluorescent proteins - photoactivated localization microscopy - resonance energy-transfer - living cells - mass-spectrometry - dynamic-range - time - ca2+ - resolution - indicators
    Genetically encoded biosensors are increasingly used in visualising signalling processes in different organisms. Sensors based on green fluorescent protein technology are providing a great opportunity for using Förster resonance energy transfer (FRET) as a tool that allows for monitoring dynamic processes in living cells. The development of these FRET biosensors requires careful selection of fluorophores, substrates and recognition domains. In this review, we will discuss recent developments, strategies to create and optimise FRET biosensors and applications of FRET-based biosensors for use in the two major eukaryotic kingdoms and elaborate on different methods for FRET detection.
    Bioactivity screening and mass spectrometric confirmation for the detection of PPAR-delta agonists that increase type 1 muscle fibres
    Bovee, T.F.H. ; Blokland, M.H. ; Kersten, A.H. ; Hamers, A.R.M. ; Heskamp, H.H. ; Essers, M.L. ; Nielen, M.W.F. ; Ginkel, L.A. van - \ 2014
    Analytical and Bioanalytical Chemistry 406 (2014). - ISSN 1618-2642 - p. 705 - 713.
    human skeletal-muscle - gamma - macrophages - expression - receptors - cells - acid - gene - fat
    Sensitive and robust bioassays able to detect nuclear receptor activation are very useful for veterinary and doping control, pharmaceutical industry and environmental scientists. Here, we used bioassays based on human leukemic monocyte lymphoma U937 and human liver hepatocellular carcinoma HepG2 cell lines to detect the ligand-induced activation of the peroxisome proliferator-activated receptor delta (PPARd). Exposure of U937 cells to the PPARd agonist GW501516 resulted in a marked increase in mRNA expression of the PPARd target gene Angptl4 which was quantified by qRTPCR analysis. Exposure ofHepG2 cells transiently transfected with a PPARd expression plasmid and a PPAR-response element-driven luciferase reporter plasmid to PPARd agonists GW501516, GW610742 and L-165041 resulted in clear dose–response curves. Although the qRT-PCR resulted in higher fold inductions, the luciferase assay with transfected HepG2 cells is cheaper and quicker and about ten times more sensitive to GW501516 compared to analysis of Angptl4 mRNA expression in U937 cells by qRT-PCR. The HepG2- based luciferase assay was therefore used to screen GW501516-spiked supplements and feed and water samples. After liquid extraction and clean-up by solid phase extraction using a weak anion exchange column, extracts were screened in the HepG2 bioassay followed by confirmation with a newly developed UPLC-MS/MS method, using two transitions for each compound, i.e., for GW501516, 454.07>188.15 (collision energy (CE) 46 V) and 454.07>257.08 (CE 30 V); for GW610742, 472.07>206.2 (CE 48 V) and 472.07>275.08 (CE 30 V); and for L-165041, 401.2>193.15 (CE 26 V) and 401.2>343.2 (CE 20 V).
    Validation of a recombinant cell bioassay for the detection of (gluco)corticosteroids in feed
    Bovee, T.F.H. ; Heskamp, H.H. ; Helsdingen, J.R. ; Hamers, A.R.M. ; Brouwer, B.A. ; Nielen, M.W.F. - \ 2013
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 30 (2013)2. - ISSN 1944-0049 - p. 264 - 271.
    glucocorticoid receptor - liquid-chromatography - mass-spectrometry - growth promoters - calf urine - performance - induction - steroids
    Use of hormones for fattening purposes is forbidden in the animal production in Europe (European Commission. 1996. Council Directive EC/96/22 (replacement of 88/146/EC). Off J Eur Commun. L125:3–9; European Commission. 1996. Council Directive EC/96/23. Off J Eur Commun. L125:10–32). Moreover, Regulation (EC) 178/2002 (European Commission. 2002. Regulation EC No 178/2002. Off J Eur Commun. L31:1–24) and Regulation (EC) 882/2004 (European Commission. 2004. Regulation EC No 882/2004. Off J Eur Commun. L165:1–135) oblige the member states to identify emerging risks and use validated and accredited methods for control analysis. Only combinations of bioassay activity screening with chemical identification are suited to uphold all laws. No such combination is described for the detection of (gluco)corticoids. In the present study, the GR-CALUX bioassay was validated as a qualitative screening method for the determination of glucocorticoid activity in feed. This validation was performed according to EC Decision 2002/657/EC (European Commission. 2002. Commission Decision 2002/657/EC from Directive 96/23. Off J Eur Commun. L221:8–36). Twenty-two representative blank feed samples were selected and spiked with 50¿ng¿g-1 of dexamethasone, 100¿ng¿g-1 of betamethasone or 500¿ng¿g-1 of triamcinolone. All blank and spiked feed samples fulfilled the CCa and CCß criteria; the method was specific and robust and glucocorticoids in feed were stable for at least 88 days.
    CD1d-restricted NKT cell function prevents insulin resistance in lean mice, and is regulated by adipocytes and is regulated by adipocytes
    Schipper, Henk S. ; Rakhshandehroo, Maryam ; Graaf, Stan F. van de; Venken, Koen ; Koppen, Arjen ; Stienstra, Rinke ; Prop, Serge ; Meerding, Jenny ; Hamers, Nicole ; Besra, Gurdyal ; Boon, Louis ; Nieuwenhuis, Edward E. ; Elewaut, Dirk ; Prakken, Berent ; Kersten, Sander ; Boes, Marianne ; Kalkhoven, Eric - \ 2012
    Wageningen University
    Mus musculus - GSE39534 - PRJNA171064 - Mus musculus - GSE39534
    Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell–deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue–resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue–resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance.
    Semiconductors (ICANS)
    Jong, M.M. de; Rath, J.K. ; Schropp, R.E.I. ; Sonneveld, P.J. ; Swinkels, G.L.A.M. ; Holterman, H.J. ; Baggerman, J. ; Rijn, C.J.M. ; Hamers, E.A.G. - \ 2012
    Journal of Non-Crystalline Solids 358 (2012)17. - ISSN 0022-3093 - p. 2308 - 2312.
    We present a novel method to achieve light trapping in thin film silicon solar cells. Unlike the commonly used surface textures, such as Asahi U-type TCO, that rely on light scattering phenomena, we employ embossed periodically arranged micro-pyramidal structures with feature sizes much larger than the wavelength of visible light. Angular resolved transmission of light through these substrates indeed showed diffraction patterns. unlike in the case of Asahi U-type substrates, which show angular resolved scattering. Single junction amorphous silicon (a-Si) solar cells made at 125 degrees C on the embossed structured polycarbonate (PC) substrates showed an increase in current density by 24% compared to a similar solar cell on a flat substrate. The band gap and thickness of the i-layer made by VHF PECVD are 1.9 eV and 270 nm respectively. A double p-layer (nc-Si:H/a-Si:H) was used to make proper contact with ZnO:Al TCO. Numerical modeling, called DokterDEP was performed to fit the dark and light current-voltage parameters and understand the characteristics of the cell. The output parameters from the modeling suggest that the cells have excellent built-in potential (V-bi). However, a rather high recombination voltage, V-mu affects the FF and short circuit current density (J(sc)) for the cells on Asahi as well as for the cells on PC. A rather high parallel resistance >> M Omega cm(2) (obtained from the modeling) infers that there is no significant shunt leakage, which is often observed for solar cells made at low temperatures on rough substrates. An efficiency of more than 6% for a cell on PC shows enormous potential of this type of light trapping structures.
    Inventarisatie ondernemerschapsproducten voor Ondernemers Academie
    Hamers-van den Berkmortel, N.W.T.H. ; Mensink, W. - \ 2012
    Ondernemers Academie een initiatief van Partners voor Ondernemerschap - 208
    agrarisch onderwijs - ondernemerschap - onderwijsmiddelen - levenslang leren - kennisvalorisatie - vaardigheden - inventarisaties - agricultural education - entrepreneurship - educational resources - lifelong learning - knowledge exploitation - skills - inventories
    Naar verwachting wordt eind 2011 de Ondernemers Academie opgericht. De Ondernemers Academie wil het ondernemerschap in Nederland versterken. Missie van de Ondernemers Academie is: De Ondernemers Academie inspireert met kennis en kunde de ondernemer in de groene ruimte. De Ondernemers Academie is een initiatief van Partners voor Ondernemerschap. De inventarisatie is uitgevoerd om de consistentie en verbinding in het huidige aanbod van ‘onderwijsproducten/ondernemerschapsonderwijs’ beter in beeld te brengen.
    Limburgse varkenshouderij 2020 : aanbevelingen voor Limburgse varkenshouders en hun omgeving
    Bergevoet, R.H.M. ; Hamers-van den Berkmortel, N.W.T.H. - \ 2012
    [Den Haag] : LEI Wageningen UR - 15
    varkenshouderij - duurzame landbouw - duurzame veehouderij - limburg - pig farming - sustainable agriculture - sustainable animal husbandry - limburg
    De Limburgse varkenshouderij staat de komende jaren voor grote uitdagingen. Een belangrijke uitdaging is onder andere het invulling en uitvoering geven aan de in de Verklaring van Roermond geformuleerde ambities. In deze verklaring hebben de Limburgse Land- en Tuinbouwbond (LLTB) en Provincie Limburg hun beeld van het toekomstige Limburgse platteland en de rol van de agrarische sector uitgesproken. De Provincie Limburg wil haar plattelandsdoelen realiseren en ondernemers in de agrarische sector streven naar een innovatieve, duurzame sector. De Limburgse intensieve veehouderij spreekt in deze Verklaring van Roermond de ambitie uit tot de meest innovatieve en duurzame veehouderijsectoren in Nederland te willen blijven behoren.
    Tegen de berg op ... en er overheen : een nieuw leertraject voor docenten in ondernemerschapsonderwijs
    Kortstee, H.J.M. ; Hamers-van den Berkmortel, N.W.T.H. van den; Oosterhoff, W. ; Boezem, E. van den - \ 2012
    Dronten : CAH Vilentum Dronten (Lectoraat Ondernemen & Samenleving 12-001) - 47
    agrarisch onderwijs - ondernemerschap - vaardigheden - leerplan - lerarenopleiding - onderwijsvaardigheden - agricultural education - entrepreneurship - skills - curriculum - teacher training - teaching skills
    Dodo (Docenten ontwikkelen doelgericht ondernemerschap) komt voort uit het programma Onderne-merschap van de Groene Kennis Coöperatie (GKC). Samen met Partners voor Ondernemerschap werken zij aan het versterken van het ondernemerschap in het Groen Onderwijs. De primaire doelgroepen hierbij zijn ondernemers in opleiding en ondernemers in de praktijk. Docenten MBO en HBO zijn daarbij belangrijke schakels: kunnen ze bij leerlingen/studenten ondernemerschapscompetenties ontwikkelen en kunnen ze bij ondernemers deze mogelijke verbeteren?
    Natural killer T cells in adipose tissue prevent insulin resistance
    Schipper, H.S. ; Rakhshandehroo, M. ; Graaf, S.F.J. van de; Venken, K. ; Koppen, A. ; Stienstra, R. ; Prop, S. ; Meerding, J. ; Hamers, N. ; Besra, G.S. ; Boon, L. den; Nieuwenhuis, E.E.S. ; Elewaut, D. ; Prakken, B. ; Kersten, A.H. ; Boes, M. ; Kalkhoven, E. - \ 2012
    The Journal of Clinical Investigation 122 (2012)9. - ISSN 0021-9738 - p. 3343 - 3354.
    invariant nkt cells - alternatively activated macrophages - nonobese diabetic mice - hepatic steatosis - metabolic syndrome - innate immunity - obese mice - inflammation - fat - disease
    Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell-deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue-resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue-resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance
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