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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    Impact of in vitro digestion on gastrointestinal fate and uptake of silver nanoparticles with different surface modifications
    Abdelkhaliq, Ashraf ; Zande, Meike van der; Undas, Anna K. ; Peters, Ruud J.B. ; Bouwmeester, Hans - \ 2020
    Nanotoxicology 14 (2020)1. - ISSN 1743-5390 - p. 111 - 126.
    bioavailability - in vitro digestion - Silver nanoparticles - single particle-ICP-MS - surface chemistry

    Nanomaterials, especially silver nanoparticles (AgNPs), are used in a broad range of products owing to their antimicrobial potential. Oral ingestion is considered as a main exposure route to AgNPs. This study aimed to investigate the impact of the biochemical conditions within the human digestive tract on the intestinal fate of AgNPs across an intestinal in vitro model of differentiated Caco-2/HT29-MTX cells. The co-culture model was exposed to different concentrations (250–2500 µg/L) of pristine and in vitro digested (IVD) AgNPs and silver nitrate for 24 h. ICP-MS and spICP-MS measurements were performed for quantification of total Ag and AgNPs. The AgNPs size distribution, dissolution, and particle concentration (mass- and number-based) were characterized in the cell fraction and in the apical and basolateral compartments of the monolayer cultures. A significant fraction of the AgNPs dissolved (86–92% and 48–70%) during the digestion. Cellular exposure to increasing concentrations of pristine or IVD AgNPs resulted in a concentration dependent increase of total Ag and AgNPs content in the cellular fractions. The cellular concentrations were significantly lower following exposure to IVD AgNPs compared to the pristine AgNPs. Transport of silver as either total Ag or AgNPs was limited (<0.1%) following exposure to pristine and IVD AgNPs. We conclude that the surface chemistry of AgNPs and their digestion influence their dissolution properties, uptake/association with the Caco-2/HT29-MTX monolayer. This highlights the need to take in vitro digestion into account when studying nanoparticle toxicokinetics and toxicodynamics in cellular in vitro model systems.

    How processing may affect milk protein digestion and overall physiological outcomes: A systematic review
    Lieshout, Glenn A.A. van; Lambers, Tim T. ; Bragt, Marjolijn C.E. ; Hettinga, Kasper A. - \ 2019
    Critical Reviews in Food Science and Nutrition (2019). - ISSN 1040-8398
    aggregation - bioavailability - Dairy - denaturation - glycation - protein quality

    Dairy is one of the main sources for high quality protein in the human diet. Processing may, however, cause denaturation, aggregation, and chemical modifications of its amino acids, which may impact protein quality. This systematic review covers the effect of milk protein modifications as a result of heating, on protein digestion and its physiological impact. A total of 5363 records were retrieved through the Scopus database of which a total of 102 were included. Although the degree of modification highly depends on the exact processing conditions, heating of milk proteins can modify several amino acids. In vitro and animal studies demonstrate that glycation decreases protein digestibility, and hinders amino acid availability, especially for lysine. Other chemical modifications, including oxidation, racemization, dephosphorylation and cross-linking, are less well studied, but may also impact protein digestion, which may result in decreased amino acid bioavailability and functionality. On the other hand, protein denaturation does not affect overall digestibility, but can facilitate gastric hydrolysis, especially of β-lactoglobulin. Protein denaturation can also alter gastric emptying of the protein, consequently affecting digestive kinetics that can eventually result in different post-prandial plasma amino acid appearance. Apart from processing, the kinetics of protein digestion depend on the matrix in which the protein is heated. Altogether, protein modifications may be considered indicative for processing severity. Controlling dairy processing conditions can thus be a powerful way to preserve protein quality or to steer gastrointestinal digestion kinetics and subsequent release of amino acids. Related physiological consequences mainly point towards amino acid bioavailability and immunological consequences.

    An integrated look at the effect of structure on nutrient bioavailability in plant foods
    Capuano, Edoardo ; Pellegrini, Nicoletta - \ 2019
    Journal of the Science of Food and Agriculture 99 (2019)2. - ISSN 0022-5142 - p. 493 - 498.
    bioavailability - digestion - food matrix - health - structure

    The true bioavailability of a nutrient being intrinsically coupled to the specific food matrix in which it occurs remains poorly considered in nutrition science. During digestion, the food matrix and, in particular, the structure of food modulate the extent and kinetics to which nutrients and bioactive compounds make themselves available for absorption. In this perspective, we describe an integrated look at the effect of structure on nutrient bioavailability in plant foods. Based on this integrated look, cell wall integrity and the particle size of the plant material during its transit in the small intestine determine the bioavailability of plant nutrients; in turn, cell wall integrity and particle size are determined by the level of oral processing and, accordingly, what subsequently escapes digestion in the upper intestine and is utilized by colon microbiota. Ultimately, the effect on nutrient digestion is linked to food structure through each step of digestion. A consideration of the structure rather than just the composition of foods opens up possibilities for the design of healthier foods.

    Green and Black Tea Phenolics : Bioavailability, Transformation by Colonic Microbiota, and Modulation of Colonic Microbiota
    Liu, Zhibin ; Bruins, Marieke Elisabeth ; Ni, Li ; Vincken, Jean Paul - \ 2018
    Journal of Agricultural and Food Chemistry 66 (2018)32. - ISSN 0021-8561 - p. 8469 - 8477.
    bioavailability - black tea phenolics - green tea catechins - gut microbiota - health benefits - microbial metabolism

    Monomeric green tea catechin (GTC) and oligomeric, oxidized black tea phenolic (BTP) have shown promising health benefits, although GTC has been more extensively studied than BTP. We review the current knowledge on bioavailability, colonic transformation, and gut microbiota modulatory effects of GTC and BTP. As a result of their similar poor bioavailability in the small intestine and potentially similar metabolites upon colonic fermentation, it seems as if GTC and BTP have similar health effects, although it cannot be excluded that they have different gut microbiota modulatory effects and that BTP gives a poorer yield of bioactive phenolic metabolites upon colonic fermentation than GTC.

    Read-across of ready biodegradability based on the substrate specificity of N-alkyl polypropylene polyamine-degrading microorganisms
    Geerts, R. ; Ginkel, C.G. van; Plugge, C.M. - \ 2017
    SAR and QSAR in Environmental Research 28 (2017)4. - ISSN 1062-936X - p. 311 - 323.
    bioavailability - N-alkyl polypropylene polyamine - read-across - ready biodegradability - substrate specificity
    The biodegradation of N-alkyl polypropylene polyamines (NAPPs) was studied using pure and mixed cultures to enable read-across of ready biodegradability test results. Two Pseudomonas spp. were isolated from activated sludge with N-oleyl alkyl propylene diamine and N-coco alkyl dipropylene triamine, respectively. Both strains utilized all NAPPs tested as the sole source of carbon, nitrogen and energy for growth. Mineralization of NAPPs was independent of the alkyl chain length and the size of the polyamine moiety. NAPPs degraded in closed bottle tests (CBTs) using both river water and activated sludge. However, ready biodegradability of NAPPs with alkyl chain lengths of 16–18 carbon atoms and polyamine moieties with three and four nitrogen atoms could not be demonstrated. Biodegradation in the CBT was hampered by their limited bioavailability, making assessment of the true ready biodegradability of these highly adsorptive surfactants impossible. All NAPPs are therefore classified as readily biodegradable through read-across. Read-across is justified by the broad substrate specificity of NAPP-degrading microorganisms, their omnipresence and the mineralization of NAPPs.
    Physiologically based kinetic modelling based prediction of oral systemic bioavailability of flavonoids, their metabolites, and their biological effects
    Boonpawa, Rungnapa - \ 2017
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Arjen Punt. - Wageningen : Wageningen University - ISBN 9789463430371 - 180
    flavonoids - bioavailability - modeling - metabolites - quercetin - physiology - hesperidin - flavonoïden - biologische beschikbaarheid - modelleren - metabolieten - quercetine - fysiologie - hesperidine

    Flavonoids, abundantly present in fruits and vegetables, have been reported to exert various positive health effects based on in vitro bioassays. However, effects detected in in vitro models cannot be directly correlated to human health as most in vitro studies have been performed using flavonoid aglycones at high concentration ignoring extensive metabolism of flavonoids in the human body. To better understand positive health effects of flavonoids in humans, it is of importance to gain insight in at which form and concentration flavonoids are present in the systemic circulation after consumption. This insight can be obtained using physiologically based kinetic (PBK) computer modeling. The results obtained show that PBK modeling provides a useful additional research tool for studies on the fate of flavonoids in the human body and can reveal at what oral dose levels of flavonoids in vitro positive health effects can be expected to occur in vivo, presenting opportunities that are not easily provided by other methods.

    Selenium speciation and bioavailability in Dutch agricultural soils: the role of soil organic matter
    Supriatin, Supriatin - \ 2016
    Wageningen University. Promotor(en): Rob Comans, co-promotor(en): Liping Weng. - Wageningen : Wageningen University - ISBN 9789462579309 - 265
    agricultural soils - selenium - bioavailability - soil organic matter - grasslands - soil chemistry - fertilizers - fertilizer application - netherlands - landbouwgronden - selenium - biologische beschikbaarheid - organisch bodemmateriaal - graslanden - bodemchemie - kunstmeststoffen - bemesting - nederland

    Selenium (Se) is an essential micronutrient for animals and humans. In the food chain, the intake of Se by animals and humans depends largely on Se content in plants, whereas the major source of Se in plants lies in the soil. Therefore, understanding Se bioavailability in soils for plant uptake and its controlling factors and mechanisms is important. The objective of this thesis is to study the amount, speciation, bioavailability, plant uptake and fertilization of Se in agricultural soils in the Netherlands and underlying controlling factors and mechanisms, to provide guidance for soil testing and fertilization recommendation for efficient Se management in agriculture.

    The majority of agricultural soils (grassland and arable land) in the Netherlands contains low total Se (i.e. in the range of Se deficient), which is predominantly present as organic Se. Only a small fraction of total Se is present as inorganic Se (mainly as selenite) and residual Se. In this thesis, the evidences of association between Se and soil organic matter in these low Se soils have been shown. The associations include: (1) the total Se content is positively correlated to soil organic matter content; (2) the solubility and extractability of Se in soils follow the solubility and extractability of soil organic C; (3) the majority of Se present in soils is in organic form, both in the soil solution and solid phase; (4) the distributions of Se and organic C in the different fractions of solid organic matter (i.e. humic acids, hydrophobic organic neutral, hydrophilic acids) and dissolved organic matter (i.e. hydrophilic acids and fulvic acids) are comparable; and (5) the Se richness in solid and dissolved organic matter are related to properties of soil organic matter from different land uses. The relatively high soil organic matter content in these low Se soils is likely responsible for these associations.

    In general, Se content in crops (e.g. grass and wheat) grown on grassland soils and arable land soils, respectively in the Netherlands is low due to low amount of bioavailable Se in the soils. Different soil parameters determine Se plant uptake in these low Se soils with predominantly organic Se, depending on the properties of Se-containing soil organic matter. The intensity parameter of Se-rich dissolved organic matter (DOM) in soil solution (i.e. Se to DOC ratio in 0.01 M CaCl2 extraction) determines Se plant uptake in soils containing Se-rich organic matter (e.g. potato arable land soils), whereas the buffer capacity of labile organic Se to supply Se-rich DOM in soil solution limits Se plant uptake in soils containing Se-poor organic matter (e.g. grassland soils). Further research is needed to confirm the generality of the conclusion above, because the two experiments were carried out under different conditions (pot experiment and field experiment), using different plant species (wheat and grass) and covering different soil types from different land uses (potato fields and grassland). Site-specific properties in the field in addition to soil parameters included in the current study may largely (> 50%) determine Se content in grass under field conditions, which is in contrast with the results of the pot experiment in which the soil parameter explains 88% of Se content in wheat shoots. In general, the content of Se-rich DOM in soils increases with the increase of soil pH (with the decrease of soil C:N ratio), and the amount of labile organic matter in soils that can resupply Se-rich DOM is determined by the amount of clay (and Fe-(hydr)oxide). NPK fertilization, as one of the external factors, can reduce Se plant uptake, especially in organic-rich soils.

    Selenium (as selenate) fertilization on grassland with N plus cattle slurry or NPK application shows a positive effect to increase Se content in grass grown on different soil types with a large range of total Se, pH, clay content and organic matter content. Selenium content in grass grown on different soil types upon Se fertilization becomes more similar than before the fertilization. The results indicate that the effectiveness of Se fertilization is only weakly modified by soil properties, probably due to the high solubility of selenate in the soils. Nevertheless, the Se fertilization tends to be slightly more effective on sandy soils than on clay and organic rich soils.

    This thesis has shown that the content and quality of soil organic matter play an important role in determining the amount, speciation and bioavailability of Se in low Se soils with predominantly organic Se. The results in this thesis can be used as guidance to develop soil testing and fertilization recommendation for efficient Se management, especially in low Se soils with predominantly organic Se, such as in Dutch agricultural soils.

    Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems : An overview
    Hullebusch, Eric D. van; Guibaud, Gilles ; Simon, Stéphane ; Lenz, Markus ; Yekta, Sepehr Shakeri ; Fermoso, Fernando G. ; Jain, Rohan ; Duester, Lars ; Roussel, Jimmy ; Guillon, Emmanuel ; Skyllberg, Ulf ; Almeida, C.M.R. ; Pechaud, Yoan ; Garuti, Mirco ; Frunzo, Luigi ; Esposito, Giovanni ; Carliell-Marquet, Cynthia ; Ortner, Markus ; Collins, Gavin - \ 2016
    Critical Reviews in Environmental Science and Technology 46 (2016)16. - ISSN 1064-3389 - p. 1324 - 1366.
    Anaerobic digestion - analytical methods - bioavailability - fractionation - speciation - trace elements

    Optimal supply of trace elements (TE) is a prerequisite for microbial growth and activity in anaerobic digestion (AD) bioprocesses. However, the required concentrations and ratios of essential TE for AD biotechnologies strongly depend on prevailing operating conditions as well as feedstock composition. Furthermore, TE in AD bioreactors undergo complex physicochemical reactions and may be present as free ions, complex bound or as precipitates depending on pH, or on the presence of sulfur compounds or organic macromolecules. To overcome TE deficiency, various commercial mineral products are typically applied to AD processes. The addition of heavy metals poses the risk of overdosing operating systems, which may be toxic to microbial consortia and ultimately the environment. Adequate supplementation, therefore, requires appropriate knowledge not only about the composition, but also on the speciation and bioavailability of TE. However, very little is yet fully understood on this specific issue. Evaluations of TE typically only include the measurement of total TE concentrations but do not consider the chemical forms in which TE exist. Thus detailed information on bioavailability and potential toxicity cannot be provided. This review provides an overview of the state of the art in approaches to determine bioavailable TE in anaerobic bioprocesses, including sequential fractionation and speciation techniques. Critical aspects and considerations, including with respect to sampling and analytical procedures, as well as mathematical modeling, are examined. The approaches discussed in this review are based on our experiences and on previously published studies in the context of the “COST Action 1302: European Network on Ecological Roles of Trace Metals in Anaerobic Biotechnologies.”

    Validation of ISO 17586 soil quality : extraction of trace elements using dilute nitric acid
    Vark, W. van; Harmsen, J. - \ 2016
    Alterra, Wageningen-UR (Alterra-rapport 2693) - 55
    soil - soil quality - trace elements - standards - bioavailability - iso - extraction - bodem - bodemkwaliteit - sporenelementen - normen - biologische beschikbaarheid - iso - extractie
    Improvement of risk assessment by integrating toxicological and epidemiological approaches: the case of isoflavones
    Islam, M.A. - \ 2015
    Wageningen University. Promotor(en): Ivonne Rietjens; Rolaf van Leeuwen; Tinka Murk. - Wageningen : Wageningen University - ISBN 9789462574649 - 174
    isoflavones - glucosides - soyabeans - toxic substances - bioavailability - biomarkers - human nutrition research - risk-benefit analysis - gene expression - isoflavonen - glucosiden - sojabonen - toxische stoffen - biologische beschikbaarheid - biomarkers - voedingsonderzoek bij de mens - risico-baten analyse - genexpressie

    Improvement of risk assessment by integrating toxicological and epidemiological approaches: the case of isoflavones

    PhD-thesis Mohammed Ariful Islam

    This thesis describes the results of a research project that aimed at the improvement of the risk/benefit assessment of soy isoflavones (SIF) by combining toxicological and epidemiological methods. The toxicological studies were carried out at the Department of Toxicology and part of the results were compared with the outcome of human intervention studies, that were carried out in parallel research project at the Division of Human Nutrition. In Chapter 1 it is explained why we considered such an integrated “tox-epi” approach to be useful for the prediction of possible effects of SIF in humans on the basis of animal data. SIF are constituents of soy based supplements, which became more and more popular in Western societies over the last decades, because of their putative beneficial health effects, that were related to the SIF present in these supplements. In spite of the long and safe history of soy consumption by the East and the South-East Asian population, the benefit and safety of soy have been challenged in recent years and concerns have been raised about possible adverse health effects. These concerns focussed primarily on the weak estrogenic and proliferative effects of SIF. Chapter 1 also provides some background information on the individual SIF, their structural similarity with the steroid hormone estradiol (E2) and their interaction with the estrogen receptors ERα and ERβ.

    Chapter 2 describes the differences between rats and humans in the conversion of the three major soy isoflavone glucosides, daidzin, genistin and glycitin, and their aglycones in a series of in vitro models. Results of studies in a Caco-2 transwell model confirmed that deconjugation of the isoflavone glucosides is essential for their transport across the intestinal barrier. It was shown that both rat and human intestinal S9 fractions were able to deconjugate the glucosides, and that intestinal enzymes plaid an important role in this deconjugation reaction. It was demonstrated that in the rat lactase phlorizin hydrolase, glucocerebrosidase, and cytosolic broad-specificity β-glucosidase contribute significantly to this deconjugation, and that in humans deconjugation mainly appeared to occur through the activity of broad-specificity β-glucosidase. Species difference in glucuronidation and sulfation were smaller than for the deconjugation reaction, and it was shown that 7-O-glucuronides were the major metabolites for all the three isoflavone aglycones. The in vitro results also indicated that glucuronidation in rats might be more efficient than in humans, again pointing towards species differences in the metabolism of isoflavone glycosides between rats and humans. It was also shown that the reconjugation reaction has a larger catalytic efficiency than the deconjugation of the glucosides, which corroborates that the detection of aglycones in the systemic circulation is unlikely.

    It has been reported in literature that following administration of SIF to humans or animals, these compounds are mainly (~98%) present in the systemic circulation in their conjugated form (i.e. as glucuronide and sulphate) of which the estrogenic potency is not yet clear. Chapter 3 provides evidence that in an intact cellular model the major SIF glucuronide metabolites in blood, genistein-7-O-glucuronide (GG) and daidzein-7-O-glucuronide (DG), only become estrogenic after deconjugation. The estrogenic potencies of genistein (Ge), daidzein (Da), GG and DG were determined using stably transfected U2OS-ERα, U2OS-ERβ reporter gene cells and proliferation was tested in T47D-ERβ and in T47D breast cancer cells. In all these assays the estrogenic potency of the aglycones was significantly higher than that of their corresponding glucuronides. UPLC analysis revealed that in the in vitro cell line assays, 0.2-1.6% of the glucuronides were deconjugated to their corresponding aglycones. It was also found that, under similar experimental conditions, rat breast tissue S9 fraction was about 30 times more potent in deconjugating these glucuronides than human breast tissue S9 fraction. The results presented in Chapter 3 confirm that SIF glucuronides are not estrogenic as such when tested in an intact cellular model system, and that the small fraction of aglycones account for the observed estrogenic effects. They also provide evidence for a significant species difference in the metabolism of SIF.

    In Chapters 4 and 5 of this thesis, two rat studies are described, that were performed to further elucidate important modes of action underlying biological effects of SIF and to facilitate an interspecies comparison of the effects observed in rats with those observed in human intervention studies. In these studies inbred ovariectomized Fischer344 rats were used, as an animal model for (post)menopausal women. In the first study described in Chapter 4, two dose levels (i.e. 2 and 20 mg/kg bw) were used to characterise plasma bioavailability, urinary and faecal concentrations of SIF and to investigate changes in gene expression in peripheral blood mononuclear cells (PBMC). The low dose was in line with the type of dosing relevant for human supplement use. Animals were dosed at 0 and 48 hr and sacrificed 4 hr after the last dose. A clear dose dependent increase of SIF concentrations in plasma, urine and faeces was observed, together with a strong correlation in changes in gene expression between the two dose groups. In the transcriptomic analysis, all estrogen responsive genes (ERG) and related biological pathways (BPs) that were found to be affected by the SIF treatment were regulated in both dose groups in the same direction, and indicate possible beneficial effects of SIF. However, most of the common genes in PBMC of rats and of (post)menopausal women, exposed to a comparable dose of the same supplement, were regulated in opposite direction. Thus based on these results no correlation was found between the changes in gene expression in rats and humans, leading to the conclusion that rats might not be a suitable model for humans.

    In Chapter 5 an animal experiment is described, in which rats received a dose of 2 mg SIF/kg body weight per day for a period of eight weeks. This dosing regimen was similar as that of the parallel human intervention study. Changes in gene expression in different target (i.e. breast (BT), uterus (UT) and sternum (ST)) and non-target (i.e. peripheral blood mononuclear cells (PBMC), adipose (AT) and liver (LT)) tissues were compared. Rank-rank scattered plots did not show any correlation in gene expression changes among different tissues. Out of 87 estrogen responsive genes (ERG), only 19 were found to be significantly regulated (p<0.05) in different tissues. The significantly regulated ERG were mostly found in LT, AT and UT. Surprisingly, no ERG were significantly regulated in BT and ST, although these are considered to be important estrogen sensitive target tissues. No correlation was observed with the changes in gene expression in the PBMC of two rat studies. Correlation was also not seen in the changes of gene expression in PBMC and adipose tissue between rat and humans.

    In Chapter 6 the results of the research project described in this thesis are evaluated. It was the aim of thesestudies to contribute to theimprovement ofthe risk and/or benefit assessment of SIF for humans, by using in vitro and in vivo animal and human models, and gene expression data in various animal and human tissues, as early biomarkers of effects of exposure to SIF. Although important information has been gathered on the metabolism and the estrogenic activity of SIF and their aglycones, we were not able to predict possible effects in human target tissues based on the results of changes in gene expression in target tissues obtained in the 8 weeks rat study. Possibly aged rats might be a more appropriate model than young ovariectomized rats.

    Direct comparison of metabolic health effects of the flavonoids quercetin, hesperetin, epicatechin, apigenin and anthocyanins in high-fat-diet-fed mice
    Hoek-van den Hil, E.F. ; Schothorst, E.M. van; Stelt, I. van der; Swarts, J.J.M. ; Vliet, M.A. van; Amolo, T. ; Vervoort, J.J.M. ; Venema, D.P. ; Hollman, P.C.H. ; Rietjens, I.M.C.M. ; Keijer, J. - \ 2015
    Genes & Nutrition 10 (2015)4. - ISSN 1555-8932 - 13 p.
    cardiovascular-disease - mediterranean diet - c57bl/6j mice - obese mice - bioavailability - polyphenols - inflammation - metaanalysis - cholesterol - prevention
    Dietary flavonoid intake is associated with reduced risk of cardiovascular diseases, possibly by affecting metabolic health. The relative potency of different flavonoids in causing beneficial effects on energy and lipid metabolism has not been investigated. Effects of quercetin, hesperetin, epicatechin, apigenin and anthocyanins in mice fed a high-fat diet (HF) for 12 weeks were compared, relative to normal-fat diet. HF-induced body weight gain was significantly lowered by all flavonoids (17–29 %), but most by quercetin. Quercetin significantly lowered HF-induced hepatic lipid accumulation (71 %). Mesenteric adipose tissue weight and serum leptin levels were significantly lowered by quercetin, hesperetin and anthocyanins. Adipocyte cell size and adipose tissue inflammation were not affected. The effect on body weight and composition could not be explained by individual significant effects on energy intake, energy expenditure or activity. Lipid metabolism was not changed as measured by indirect calorimetry or expression of known lipid metabolic genes in liver and white adipose tissue. Hepatic expression of Cyp2b9 was strongly downregulated by all flavonoids. In conclusion, all flavonoids lowered parameters of HF-induced adiposity, with quercetin being most effective.
    In vitro selenium accessibility in pet foods is affected by diet composition and type
    Zelst, M. van; Hesta, M. ; Alexander, L.G. ; Gray, K. ; Bosch, G. ; Hendriks, W.H. ; Laing, G. Du; Meulenaer, B. de; Goethals, K. ; Janssens, G. - \ 2015
    The British journal of nutrition 113 (2015)12. - ISSN 0007-1145 - p. 1888 - 1894.
    nutrient digestion - organic selenium - bioavailability - absorption - dog - bioaccessibility - selenomethionine - metabolism - prediction - fiber
    Se bioavailability in commercial pet foods has been shown to be highly variable. The aim of the present study was to identify dietary factors associated with in vitro accessibility of Se (Se Aiv) in pet foods. Se Aiv is defined as the percentage of Se from the diet that is potentially available for absorption after in vitro digestion. Sixty-two diets (dog, n 52; cat, n 10) were in vitro enzymatically digested: fifty-four of them were commercially available (kibble, n 20; pellet, n 8; canned, n 17; raw meat, n 6; steamed meat, n 3) and eight were unprocessed (kibble, n 4; canned, n 4) from the same batch as the corresponding processed diets. The present investigation examined if Se Aiv was affected by diet type, dietary protein, methionine, cysteine, lysine and Se content, DM, organic matter and crude protein (CP) digestibility. Se Aiv differed significantly among diet types (P<0·001). Canned and steamed meat diets had a lower Se Aiv than pelleted and raw meat diets. Se Aiv correlated positively with CP digestibility in extruded diets (kibbles, n 19; r 0·540, P =0·017) and negatively in canned diets (n 16; r - 0·611, P =0·012). Moreover, the canning process (n 4) decreased Se Aiv (P =0·001), whereas extrusion (n 4) revealed no effect on Se Aiv (P =0·297). These differences in Se Aiv between diet types warrant quantification of diet type effects on in vivo Se bioavailability.
    Development of an integrated in vitro model for the prediction of oral bioavailability of nanoparticles
    Walczak, A.P. - \ 2015
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Hans Bouwmeester; Peter Hendriksen. - Wageningen : Wageningen University - ISBN 9789462572201 - 153
    nanotechnologie - deeltjes - in vitro - inname - biologische beschikbaarheid - voedingsonderzoek bij de mens - risicoschatting - nanotechnology - particles - in vitro - ingestion - bioavailability - human nutrition research - risk assessment

    Title of the PhD thesis: Development of an integrated in vitro model for the prediction of oral bioavailability of nanoparticles

    The number of food-related products containing nanoparticles (NPs) increases. To understand the safety of such products, the potential uptake of these NPs following consumption needs to be assessed. In normal safety assessment studies this is investigated using animal models. For scientific, ethical and economical reasons, there is a demand to refine, reduce and replace animal testing by developing in vitro alternatives for hazard characterization. In this thesis an in vitro model for the prediction of the uptake of NPs in the human body after consumption was developed. The model consists of two parts. The first part is a laboratory incubation model mimicking human digestion in mouth, stomach and intestine. For the second part, human intestinal wall cells are used to assess the uptake of nanoparticles. The two models were combined into the integrated in vitro model to take into consideration the potential effect of digestion on nanoparticle uptake in the gut. The main outcome of the work is that the cell-based integrated in vitro model can be used to evaluate which NPs are likely taken up by the body at the highest rate. The size of NPs and the type of chemical groups on their surface greatly influenced the uptake of NPs. The developed model can be used to prioritize the NPs for additional investigations. Using this model in the safety assessment of NPs would reduce the number of animals used in safety assessment.

    Effects of azoxystrobin, chlorothalonil and ethoprophos on the reproduction of three terrestrial invertebrates using a natural Mediterranean soil
    Leitao, S. ; Cerejeira, J. ; Brink, P.J. van den; Sousa, J.P. - \ 2014
    Applied Soil Ecology 76 (2014). - ISSN 0929-1393 - p. 124 - 131.
    enhanced biodegradation - enchytraeus-albidus - folsomia-candida - eisenia-foetida - pesticides - toxicity - bioavailability - c-14-lindane - earthworms - greece
    The potential terrestrial toxicity of three pesticides, azoxystrobin, chlorothalonil, and ethoprophos was evaluated using reproduction ecotoxicological tests with different non-target species: the collembolan Folsomia candida, the earthworm Eisenia andrei, and the enchytraeid Enchytraeus crypticus. All reproduction tests were performed with natural soil from a Mediterranean agricultural area (with no pesticide residues) in order to improve the relevance of laboratory data to field conditions. Controls were performed with natural and standard artificial soil (OECD 10% OM). The fungicide azoxystrobin showed the highest toxicity to earthworms (EC50 = 42.0 mg a.i. kg-1 dw soil). Collembolans were the most sensitive taxa in terms of sublethal effects of chlorothalonil with an EC50 of 31.1 mg a.i. kg-1 dw soil followed by the earthworms with an EC50 of 40.9 mg a.i. kg-1 dw soil. The insecticide ethoprophos was the most toxic to collembolans affecting their reproduction with an EC50 of 0.027 mg a.i. kg-1 dw soil. Enchytraeids were generally the least sensitive of the three species tested for long-term effects. Earthworms were not always the most sensitive species, emphasizing the need to increase the number of mandatory assays with key non-target organisms in the environmental risk assessment of pesticides
    Nutrikinetic modeling reveals order of genistein phase II metabolites appearance in human plasma
    Smit, S. ; Szymanska, E. ; Kunz, I. ; Gomez Roldan, V. ; Tilborg, M.W.E.M. van; Weber, P. ; Prudence, K. ; Kloet, F.M. van der; Duynhoven, J.P.M. van; Smilde, A.K. ; Vos, R.C.H. de; Bendik, I. - \ 2014
    Molecular Nutrition & Food Research 58 (2014)11. - ISSN 1613-4125 - p. 2111 - 2121.
    isoflavone glycosides - soybean isoflavones - healthy-volunteers - bioavailability - pharmacokinetics - disposition - women - daidzein - breast - identification
    Scope: Genistein from foods or supplements is metabolized by the gut microbiota and the human body, thereby releasingmany different metabolites into systemic circulation. The order of their appearance in plasma and the possible influence of food format are still unknown. This study compared the nutrikinetic profiles of genistein metabolites. Methods and results: In a randomized cross-over trial, 12 healthy young volunteers were administered a single dose of 30mggenistein provided as a genistein tablet, a genistein tablet in low fat milk, and soy milk containing genistein glycosides. A high mass resolution LC-LTQ-Orbitrap FTMS platform detected and quantified in human plasma: free genistein, seven of its phase-II metabolites and 15 gut-derived metabolites. Interestingly, a novel metabolite, genistein-4- glucuronide-7-sulfate (G-4 G7S) was identified. Nutrikinetic analysis using population-based modeling revealed the order of appearance of five genistein phase II metabolites in plasma: (1) genistein-4,7-diglucuronide, (2) genistein-7-sulfate, (3) genistein-4--sulfate-7-glucuronide, (4) genistein-4-glucuronide, and (5) genistein-7-glucuronide, independent of the food matrix. Conclusion: The conjugated genistein metabolites appear in a distinct order in human plasma. The specific early appearance of G-4 ,7-diG suggests a multistep formation process for the mono and hetero genistein conjugates, involving one or two deglucuronidation steps.
    Chemical and biological rhizosphere interactions in low zinc soils
    Duffner, A. - \ 2014
    Wageningen University. Promotor(en): Ellis Hoffland; Sjoerd van der Zee, co-promotor(en): Erwin Temminghoff. - Wageningen : Wageningen University - ISBN 9789462571631 - 131
    bodem - zink - rizosfeer - voedingsstoffentekorten - bodemkunde - planten - voedingsstoffenopname (planten) - biologische beschikbaarheid - bodemkwaliteit - bodemvruchtbaarheid - soil - zinc - rhizosphere - nutrient deficiencies - soil science - plants - nutrient uptake - bioavailability - soil quality - soil fertility

    Abstract of the PhD thesis entitled “Chemical and biological rhizosphere

    interactions in low zinc soils” by Andreas Duffner

    Soil provides ecosystem services critical for life. The availability of micronutrients, such as zinc (Zn), in soils is an essential factor for normal healthy growth and reproduction of plants. Zinc deficiency is, however, a global problem in crop production due to low Zn bioavailability in soils to plants. The bioavailable Zn fraction in soils is controlled by several factors and is not directly related to the total Zn content of soils. The main objective of this thesis was the determination of factors which control Zn bioavailability in soils to plants and to assess approaches to improve the prediction of Zn plant uptake.

    Based on rhizobox experiments, in situ measurements in the rhizosphere as well as multisurface- and radial transport modeling approaches it was shown that the effect of root exuded citrate for increasing plant available Zn is soil specific and does not depend on a specific concentration of low molecular weight organic acids (e.g. citric acid) in the soil solution. Using various low Zn soils at the same time in an experimental setting improved the understanding of soil-responsiveness to root exuded citrate.

    Another insight was that multisurface models, which are widely used to assess the potential ecotoxicological risk in metal-contaminated soils, are also accurate to predict the Zn activity in soils with low Zn levels. The predictions were validated with the soil column Donnan Membrane Technique by using various soils with low Zn levels. It was predicted that soil organic matter is the dominant Zn sorbent and controlled the Zn activity also at low soil organic matter levels. Examples were shown how this modeling approach can be used to assess management options to increase bioavailable Zn to plants.

    Using soil extracted Zn fractions to directly predict the Zn plant uptake at low Zn levels was shown to be inaccurate. Using a stepwise approach where the steps of the uptake process were characterized with, respectively, Zn solid-solution distribution, adsorption of Zn to root surface, Zn uptake into root and Zn translocation to shoot made the prediction of Zn plant uptake more accurate. Root surface adsorbed Zn was shown to be a useful proxy for the bioavailable Zn.

    The framework of experimental and modeling approaches which were developed and applied in this thesis can also be used to study the plant-availability of other micronutrients at low concentration levels and how that is affected by various root exuded ligands.

    Food matrix effects on bioaccessibility of B-Carotene can be measured in a vitro gastrointestinal model
    Loo-Bouwman, C.A. van; Naber, T.H.J. ; Minekus, M. ; Hulshof, P.J.M. ; Schaafsma, G. - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)4. - ISSN 0021-8561 - p. 950 - 955.
    green leafy vegetables - digestion method - pro-vitamin - folic-acid - accessibility - serum - bioavailability - absorption - retinol - cassava
    Since the food matrix determines ß-carotene availability for intestinal absorption, food matrix effects on the bioaccessibility of ß-carotene from two diets were investigated in vitro and compared with in vivo data. The “mixed diet” consisted of ß-carotene-rich vegetables, and the “oil diet” contained ß-carotene-low vegetables with supplemental ß-carotene. The application of extrinsically labeled ß-carotene was also investigated. The bioaccessibility of ß-carotene was 28 µg/100 µg ß-carotene from the mixed diet and 53 µg/100 µg ß-carotene from the oil diet. This ratio of 1.9:1 was consistent with in vivo data, where the apparent absorption was 1.9-fold higher in the oil diet than in the mixed diet. The labeled ß-carotene was not equally distributed over time. In conclusion, the food matrix effects on bioaccessibility of ß-carotene could be measured using an in vitro model and were consistent with in vivo data. The application of extrinsically labeled ß-carotene was not confirmed.
    Sensory and health properties of steamed and boiled carrots (Daucus carota ssp. sativus)
    Bongoni, R. ; Stieger, M.A. ; Dekker, M. ; Steenbekkers, B. ; Verkerk, R. - \ 2014
    International Journal of Food Sciences and Nutrition 65 (2014)7. - ISSN 0963-7486 - p. 809 - 815.
    beta-carotene - processed vegetables - cooking methods - fruits - texture - quality - bioavailability - pectin - juice - raw
    This study examined the influences of domestic processing conditions applied by consumers on firmness, colour and amount of phytochemicals and liking and sensory attributes intensity rating of carrots. The aim was to identify a cooking method and time that yields carrots with higher amount of b-carotene while maintaining consumer liking. Instrumentally measured firmness and colour showed comparable degradation trends between cooking methods. While boiling showed a significant decrease in the amount b-carotene after 20 min (19%), steaming maintained the amount (+40%). Cooking method did not show a significant effect on liking and intensity ratings for the majority of the sensory attributes. Medium firm carrots were liked the most and low firm carrots the least. This study demonstrates that for optimum liking, carrots should be in the range of medium firmness. This can be obtained through either cooking methods but steamed carrots possess a higher amount of b-carotene and maintains liking.
    Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessement
    Velpen, V. van der; Hollman, P.C.H. ; Nielen, M. van; Schouten, E.G. ; Mensink, M.R. ; Veer, P. van 't; Geelen, A. - \ 2014
    European Journal of Clinical Nutrition 68 (2014). - ISSN 0954-3007 - p. 1141 - 1147.
    randomized controlled-trials - soy isoflavones - premenopausal women - soybean isoflavones - equol production - gut microflora - healthy-adults - habitual diet - bioavailability - humans
    Background/objectives: Isoflavones are present in soy foods and soy-based supplements. Despite low plasma isoflavone concentrations in the general Western population, concentrations in supplement users exceed those suggested to be beneficial for health in Asian populations, raising concerns for adverse effects. To aid risk assessment, quantification of the relation between isoflavone intake and plasma concentrations is essential. Subjects/methods: Plasma samples were collected from postmenopausal women in three placebo-controlled crossover studies with 8-week periods for supplements (two studies, ~100¿mg isoflavones/day, n=88) or 4-week periods for soy foods (one study, ~48¿mg isoflavones/day, n=15). Plasma isoflavone concentrations (daidzein, equol, genistein and glycitein) were quantified using high-performance liquid chromatography and electrochemical detection. The association between plasma concentrations and isoflavone intake, equol producer status, intake–producer interaction and background dietary intake was assessed based on the assumption of a log-linear relation. Results: Median plasma total isoflavone concentrations after the soy food and supplement interventions were respectively 2.16 and 3.47¿µmol/l for equol producers and 1.30 and 2.39¿µmol/l for non-producers. Regression analysis showed that doubling isoflavone intake increased plasma concentrations by 55–62% (±s.e. 1–2%, R2>0.87) for daidzein, genistein, equol (only for producers) and total isoflavones; for glycitein the association was weaker (15±1%, R2=0.48). Adjustments for energy, carbohydrate and fat intake did not affect these estimates. Inter-individual variation, estimated based on repeated measures in one of the studies, was 30–96%. Conclusions: Although the relation between isoflavone intake and plasma concentrations was adequately quantified, the use of isoflavone intake data for risk assessment needs caution due to large inter-individual variation in plasma concentrations.
    The bioavailability of four zinc oxide sources and zinc sulphate in broiler chickens
    Veldkamp, T. ; Diepen, J.T.M. van; Bikker, P. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 806) - 27
    vleeskuikens - biologische beschikbaarheid - zink - belgië - voedingsstoffenbehoeften - excretie - excreten - landbouw en milieu - pluimveevoeding - pluimveehouderij - wetenschappelijk onderzoek - broilers - bioavailability - zinc - belgium - nutrient requirements - excretion - excreta - agriculture and environment - poultry feeding - poultry farming - scientific research
    Zinc is an essential trace element for all farm animal species. It is commonly included in animal diets as zinc oxide, zinc sulphate or organically bound zinc. Umicore Zinc Chemicals developed zinc oxide products with different mean particle sizes. Umicore Zinc Chemicals requested Wageningen UR Livestock Research to determine the bioavailability of four zinc oxide sources and zinc sulphate in broiler chickens. A precise estimate of the bioavailability of zinc sources is required both for fulfilling the zinc requirements of the animal and to reduce zinc excretion in excreta and the environment.
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