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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    Designing Eukaryotic Gene Expression Regulation Using Machine Learning
    Jongh, Ronald P.H. de; Dijk, Aalt D.J. van; Julsing, Mattijs K. ; Schaap, Peter J. ; Ridder, Dick de - \ 2020
    Trends in Biotechnology 38 (2020)2. - ISSN 0167-7799 - p. 191 - 201.
    DNA design - eukaryotic gene expression - gene regulation - machine learning - synthetic biology

    Controlling the expression of genes is one of the key challenges of synthetic biology. Until recently fine-tuned control has been out of reach, particularly in eukaryotes owing to their complexity of gene regulation. With advances in machine learning (ML) and in particular with increasing dataset sizes, models predicting gene expression levels from regulatory sequences can now be successfully constructed. Such models form the cornerstone of algorithms that allow users to design regulatory regions to achieve a specific gene expression level. In this review we discuss strategies for data collection, data encoding, ML practices, design algorithm choices, and finally model interpretation. Ultimately, these developments will provide synthetic biologists with highly specific genetic building blocks to rationally engineer complex pathways and circuits.

    Thermal stability of oxide-supported gold nanoparticles
    Masoud, Nazila ; Partsch, Tomas ; Jong, Krijn P. de; Jongh, Petra E. de - \ 2019
    Gold Bulletin 52 (2019)2. - ISSN 2364-821X - p. 105 - 114.
    Atmosphere effect - Au - Sintering - Support effect

    In this study, we report on the influence of support and gas atmosphere on the thermal stability of Au nanoparticles on oxidic supports. All samples were prepared with a modified impregnation method and have initial Au particle sizes in the range of 3–4 nm. We observed that in air, Au nanoparticles on SiO2 and Al2O3 are thermally much more stable than Au nanoparticles on TiO2. For instance, upon treatment up to 700 °C, on SiO2, Au particles grew from 4 to 6 nm while on TiO2 from 3 to 13 nm. For Au nanoparticles on TiO2, growth is accelerated by oxidizing atmospheres and the presence of water and/or chloride. On non-reducible supports and in non-oxidizing atmosphere, the supported Au nanoparticles were remarkably stable. The insight into the growth of oxide-supported Au nanoparticles in reactive atmosphere offers an additional tool for a rational choice of a support for high-temperature gas-phase reactions involving gold nanocatalysts.

    Beheersing van aardappelmoeheid in de akkerbouw : Een update! Alles over aardappelmoeheid (AM): achtergronden, regelgeving, bemonstering, bestrijding en beheersing
    Molendijk, L.P.G. ; Jongh, Edwin de - \ 2018
    Branche Organisatie Akkerbouw - 24 p.
    Stability of gold nanocatalysts supported on mesoporous silica for the oxidation of 5-hydroxymethyl furfural to furan-2,5-dicarboxylic acid
    Masoud, Nazila ; Donoeva, Baira ; Jongh, Petra E. de - \ 2018
    Applied Catalysis A-General 561 (2018). - ISSN 0926-860X - p. 150 - 157.
    Gold catalysis - Nanoparticles - Particle growth - Selective oxidation - Support morphology

    The synthesis of furan-2,5-dicarboxylic acid via catalytic oxidation of 5-hydroxymethyl furfural is an important step for the production of bio-sourced polymers. We report on the activity of SiO2-supported Au catalysts for this reaction. These catalysts reached 74% furan-2,5-dicarboxylic acid yield at 90 °C in 5 h when 5-hydroxymethyl furfural to Au molar ratio was 72. We also investigated the influence of the morphologies of the silica supports on the growth of Au nanoparticles under reaction conditions. Pronounced growth of Au nanoparticles occurred on Aerosil, SiO2 with a disordered porosity and 50 nm average pore diameter: Au nanoparticles grew from 2.4 to 10.1 nm. However, by using ordered mesoporous supports, the growth of the gold nanoparticles was successfully minimized. Also the reaction conditions influenced the particle growth; for instance using HCO3 as a base led to more pronounced particle growth than using NaOH. Particle diffusion in solution, and subsequent coalescence and agglomeration was proposed to be the dominant particle growth mechanism. Our results show the importance of support morphology in mitigation of Au particle growth in liquid phase oxidation reactions.

    β2→1-fructans modulate the immune system in vivo in a microbiota-dependent and -independent fashion
    Fransen, Floris ; Sahasrabudhe, Neha M. ; Elderman, Marlies ; Bosveld, M. ; Aidy, Sahar El; Hugenholtz, F. ; Borghuis, Theo ; Kousemaker, Ben ; Winkel, Simon ; Gaast-de Jongh, Christa van der; Jonge, Marien I. de; Boekschoten, M.V. ; Smidt, H. ; Vos, Paul de - \ 2018
    Wageningen University
    Mus musculus - GSE94516 - PRJNA371228
    It has been shown in vitro that only specific dietary-fibers contribute to immunity but studies in vivo are not conclusive. Here we investigated degree of polymerization (DP) dependent effects of β2→1-fructans on immunity via microbiota-dependent and -independent effects. To this end, conventional or germ-free mice received short- or long-chain β2→1-fructan for 5 days. Immune cell populations in the spleen, mesenteric lymph nodes (MLN), and Peyer's patches (PPs) were analyzed with flow cytometry, genome-wide gene expression in the ileum was measured with microarray, and gut microbiota composition was analyzed with 16S rRNA sequencing of fecal samples. We found that β2→1-fructans modulated immunity by both microbiota and microbiota-independent effects. Moreover, effects were dependent on the chain-length of the β2→1-fructans type polymer. Both short- and long-chain β2→1-fructans enhanced T-helper 1 cells in Peyer's patches, whereas only short-chain β2→1-fructans increased regulatory T cells and CD11b-CD103- DCs in the MLN. A common feature after short- and long-chain β2→1-fructan treatment was enhanced Fut2 expression and other IL-22-dependent genes in the ileum of conventional mice. These effects were not associated with shifts in gut microbiota composition, or altered production of short-chain fatty acids. Both short- and long-chain β2→1-fructans also induced immune effects in germ-free animals, demonstrating direct effect independent from the gut microbiota. Also, these effects were dependent on the chain-length of the β2→1-fructans. Short-chain β2→1-fructan induced lower CD80 expression by CD11b-CD103- DCs in PPs, whereas long-chain β2→1-fructan specifically modulated B cell responses in germ-free mice. In conclusion, support of immunity is determined by the chemical structure of β2→1-fructans and is partially microbiota-independent.
    Aged gut microbiota contributes to systemical inflammaging after transfer to germ-free mice
    Fransen, Floris ; Beek, A.A. van; Borghuis, Theo ; Aidy, Sahar El; Hugenholtz, F. ; Gaast-de Jongh, Christa van der; Savelkoul, H.F.J. ; Jonge, Marien I. De; Boekschoten, M.V. ; Smidt, H. ; Faas, Marijke M. ; Vos, Paul de - \ 2018
    Wageningen University
    Mus musculus - GSE104063 - PRJNA408136
    Advanced age is associated with chronic low-grade inflammation, which is usually referred to as inflammaging. Elderly are also known to have an altered gut microbiota composition. However, whether inflammaging is a cause or consequence of an altered gut microbiota composition is not clear. In this study gut microbiota from young or old conventional mice was transferred to young germ-free mice. Four weeks after gut microbiota transfer immune cell populations in spleen, Peyer’s patches, and mesenteric lymph nodes from conventionalized germ-free mice were analyzed by flow cytometry. In addition, whole-genome gene expression in the ileum was analyzed by microarray. Gut microbiota composition of donor and recipient mice was analyzed with 16S rDNA sequencing. Here we show by transferring aged microbiota to young germ-free mice that certain bacterial species within the aged microbiota promote inflammaging. This effect was associated with lower levels of Akkermansia and higher levels of TM7 bacteria and Proteobacteria in the aged microbiota after transfer. The aged microbiota promoted inflammation in the small intestine in the germ-free mice and enhanced leakage of inflammatory bacterial components into the circulation was observed. Moreover, the aged microbiota promoted increased T cell activation in the systemic compartment. In conclusion, these data indicate that the gut microbiota from old mice contributes to inflammaging after transfer to young germ-free mice.
    Silica-Supported Au–Ag Catalysts for the Selective Hydrogenation of Butadiene
    Masoud, Nazila ; Delannoy, Laurent ; Calers, Christophe ; Gallet, Jean Jacques ; Bournel, Fabrice ; Jong, Krijn P. de; Louis, Catherine ; Jongh, Petra E. de - \ 2017
    ChemCatChem 9 (2017)12. - ISSN 1867-3880 - p. 2418 - 2425.
    atomic rearrangements - Au–Ag - heterogeneous catalysis - hydrogenation - photoelectron spectroscopy

    Gold and silver are miscible over the entire composition range, and form an attractive combination for fundamental studies on bimetallic catalysts. Au–Ag catalysts have shown synergistic effects for different oxidation and liquid-phase hydrogenation reactions, but have rarely been studied for gas-phase hydrogenation. In this study 3 nm particles of Au, Ag and Au–Ag supported on silica (SBA-15) were investigated as catalysts for selective hydrogenation of butadiene in an excess of propene. The Au catalyst was over an order of magnitude more active than the Ag catalyst at 120 °C. The initial activity of the Au–Ag catalysts scaled linearly with the Au-content, suggesting a direct correlation between the surface and overall compositions of the nanoparticles and the absence of synergistic effects. All Au-containing catalysts were highly selective to butenes (>99.9 %). The Au catalysts were stable, whereas the Au–Ag catalysts lost about half of their activity during 20 h run time at 200 °C, but the initial activity was restored by a consecutive oxidation-reduction treatment. Near ambient pressure x-ray photoelectron spectroscopy showed that exposure to H2 at elevated temperatures led to a gradual enrichment of the surface of the Au–Ag nanoparticles by Ag. These observations highlight the importance of considering progressive atomic rearrangements in bimetallic nanocatalysts under reaction conditions.

    Carbon Support Surface Effects in the Gold-Catalyzed Oxidation of 5-Hydroxymethylfurfural
    Donoeva, Baira ; Masoud, Nazila ; Jongh, Petra E. de - \ 2017
    ACS Catalysis 7 (2017)7. - ISSN 2155-5435 - p. 4581 - 4591.
    5-hydroxymethylfurfural - carbon - gold nanoparticles - selective oxidation - surface functionalization

    Oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid is an important transformation for the production of bio-based polymers. Carbon-supported gold catalysts hold great promise for this transformation. Here we demonstrate that the activity, selectivity, and stability of the carbon-supported gold nanoparticles in the oxidation of 5-hydroxymethylfurfural strongly depend on the surface properties of the carbon support. Gold nanoparticles supported on basic carbon materials with a low density of functional groups demonstrate higher activity in 5-hydroxymethylfurfural oxidation (TOFAu up to 1195 h-1), higher selectivity to 2,5-furandicarboxylic acid, and better stability in comparison to gold nanoparticles supported on carbon materials with acidic surface groups. Surface groups of basic carbon supports that are positively charged under the reaction conditions result in a higher adsorption and local concentration of hydroxyl ions, which act as cocatalysts for gold and enhance gold-catalyzed dehydrogenation. Negatively charged surface groups of acidic carbons repel hydroxyls and the intermediate monoacid anions, which leads to lower reaction rates and a high selectivity toward 2,5-hydroxymethylfurancarboxylic acid. Understanding the role of support surface charge and local hydroxyl anion concentration provides a basis for the rational design of the optimal carbon support surface chemistry for highly active, selective, and stable catalysts for the oxidation of 5-hydroxymethylfurfural and related reactions. (Chemical Equation Presented).

    Superior Stability of Au/SiO2 Compared to Au/TiO2 Catalysts for the Selective Hydrogenation of Butadiene
    Masoud, Nazila ; Delannoy, Laurent ; Schaink, Herrick ; Eerden, Ad van der; Rijk, Jan Willem de; Silva, Tiago A.G. ; Banerjee, Dipanjan ; Meeldijk, Johannes D. ; Jong, Krijn P. de; Louis, Catherine ; Jongh, Petra E. de - \ 2017
    ACS Catalysis 7 (2017)9. - ISSN 2155-5435 - p. 5594 - 5603.
    butadiene - catalyst - gold - selective hydrogenation - stability - supported nanoparticles

    Supported gold nanoparticles are highly selective catalysts for a range of both liquid-phase and gas-phase hydrogenation reactions. However, little is known about their stability during gas-phase catalysis and the influence of the support thereon. We report on the activity, selectivity, and stability of 2-4 nm Au nanoparticulate catalysts, supported on either TiO2 or SiO2, for the hydrogenation of 0.3% butadiene in the presence of 30% propene. Direct comparison of the stability of the Au catalysts was possible as they were prepared via the same method but on different supports. At full conversion of butadiene, only 0.1% of the propene was converted for both supported catalysts, demonstrating their high selectivity. The TiO2-supported catalysts showed a steady loss of activity, which was recovered by heating in air. We demonstrated that the deactivation was not caused by significant metal particle growth or strong metal-support interaction, but rather, it is related to the deposition of carbonaceous species under reaction conditions. In contrast, all the SiO2-supported catalysts were highly stable, with very limited formation of carbonaceous deposits. It shows that SiO2-supported catalysts, despite their 2-3 times lower initial activities, clearly outperform TiO2-supported catalysts within a day of run time. (Graph Presented).

    Aged gut microbiota contributes to systemical inflammaging after transfer to germ-free mice
    Fransen, Floris ; Beek, Adriaan A. van; Borghuis, Theo ; Aidy, Sahar El; Hugenholtz, Floor ; Gaast - de Jongh, Christa van der; Savelkoul, Huub F.J. ; Jonge, Marien I. de; Boekschoten, Mark V. ; Smidt, Hauke ; Faas, Marijke M. ; Vos, Paul de - \ 2017
    Frontiers in Immunology 8 (2017). - ISSN 1664-3224
    Aging - Germ-free mice - Gut microbiome - Immune system - Inflammaging
    Advanced age is associated with chronic low-grade inflammation, which is usually referred to as inflammaging. Elderly are also known to have an altered gut microbiota composition. However, whether inflammaging is a cause or consequence of an altered gut microbiota composition is not clear. In this study, gut microbiota from young or old conventional mice was transferred to young germ-free (GF) mice. Four weeks after gut microbiota transfer immune cell populations in spleen, Peyer's patches, and mesenteric lymph nodes from conventionalized GF mice were analyzed by flow cytometry. In addition, whole-genome gene expression in the ileum was analyzed by microarray. Gut microbiota composition of donor and recipient mice was analyzed with 16S rDNA sequencing. Here, we show by transferring aged microbiota to young GF mice that certain bacterial species within the aged microbiota promote inflammaging. This effect was associated with lower levels of Akkermansia and higher levels of TM7 bacteria and Proteobacteria in the aged microbiota after transfer. The aged microbiota promoted inflammation in the small intestine in the GF mice and enhanced leakage of inflammatory bacterial components into the circulation was observed. Moreover, the aged microbiota promoted increased T cell activation in the systemic compartment. In conclusion, these data indicate that the gut microbiota from old mice contributes to inflammaging after transfer to young GF mice.
    The impact of gut microbiota on gender-specific differences in immunity
    Fransen, Floris ; Beek, Adriaan A. van; Borghuis, Theo ; Meijer, Ben ; Hugenholtz, Floor ; Gaast-de Jongh, Christa van der; Savelkoul, Huub F. ; Jonge, Marien I. de; Faas, Marijke M. ; Boekschoten, Mark V. ; Smidt, Hauke ; Aidy, Sahar El ; Vos, Paul de - \ 2017
    Frontiers in Immunology 8 (2017). - ISSN 1664-3224 - 14 p.
    Gender - Germ-free mice - Gut microbiota - Immunity - Inflammation

    Males and females are known to have gender-specific differences in their immune system and gut microbiota composition. Whether these differences in gut microbiota composition are a cause or consequence of differences in the immune system is not known. To investigate this issue, gut microbiota from conventional males or females was transferred to germ-free (GF) animals of the same or opposing gender. We demonstrate that microbiota-independent gender differences in immunity are already present in GF mice. In particular, type I interferon signaling was enhanced in the intestine of GF females. Presumably, due to these immune differences bacterial groups, such as Alistipes, Rikenella, and Porphyromonadaceae, known to expand in the absence of innate immune defense mechanism were overrepresented in the male microbiota. The presence of these bacterial groups was associated with induction of weight loss, inflammation, and DNA damage upon transfer of the male microbiota to female GF recipients. In summary, our data suggest that microbiota-independent gender differences in the immune system select a gender-specific gut microbiota composition, which in turn further contributes to gender differences in the immune system.

    β2→1-fructans modulate the immune system in vivo in a microbiota-dependent and -independent fashion
    Fransen, Floris ; Sahasrabudhe, Neha M. ; Elderman, Marlies ; Bosveld, Margaret ; Aidy, Sahar El; Hugenholtz, Floor ; Borghuis, Theo ; Kousemaker, Ben ; Winkel, Simon ; Gaast-de Jongh, Christa van der; Jonge, Marien I. de; Boekschoten, Mark V. ; Smidt, Hauke ; Schols, Henk A. ; Vos, Paul de - \ 2017
    Frontiers in Immunology 8 (2017). - ISSN 1664-3224
    Germ-free mice - Gut microbiota - Mucosal immunology - Prebiotics - β2→1-fructans
    It has been shown in vitro that only specific dietary fibers contribute to immunity, but studies in vivo are not conclusive. Here, we investigated degree of polymerization (DP) dependent effects of β2→1-fructans on immunity via microbiota-dependent and -independent effects. To this end, conventional or germ-free mice received short- or long-chain β2→1-fructan for 5 days. Immune cell populations in the spleen, mesenteric lymph nodes (MLNs), and Peyer's patches (PPs) were analyzed with flow cytometry, genome-wide gene expression in the ileum was measured with microarray, and gut microbiota composition was analyzed with 16S rRNA sequencing of fecal samples. We found that β2→1-fructans modulated immunity by both microbiota and microbiota-independent effects. Moreover, effects were dependent on the chain-length of the β2→1-fructans type polymer. Both short- and long-chain β2→1-fructans enhanced T-helper 1 cells in PPs, whereas only short-chain β2→1-fructans increased regulatory T cells and CD11b-CD103- dendritic cells (DCs) in the MLN. A common feature after short- and long-chain β2→1-fructan treatment was enhanced 2-alpha-l-fucosyltransferase 2 expression and other IL-22-dependent genes in the ileum of conventional mice. These effects were not associated with shifts in gut microbiota composition, or altered production of short-chain fatty acids. Both short- and long-chain β2→1-fructans also induced immune effects in germ-free animals, demonstrating direct effect independent from the gut microbiota. Also, these effects were dependent on the chain-length of the β2→1-fructans. Short-chain β2→1-fructan induced lower CD80 expression by CD11b-CD103- DCs in PPs, whereas long-chain β2→1-fructan specifically modulated B cell responses in germ-free mice. In conclusion, support of immunity is determined by the chemical structure of β2→1-fructans and is partially microbiota independent.
    Water holding as determinant for the elastically stored energy in protein-based gels
    Pouvreau, L.A.M. ; Wijlen, Emke van; Klok, Jan ; Urbonaite, V. ; Munialo, C.D. ; Jongh, H.H.J. de - \ 2016
    Journal of Food Science 81 (2016)4. - ISSN 0022-1147 - p. N982 - N990.
    elastically stored energy - predictive values - protein gels - Water holding
    To evaluate the importance of the water holding capacity for the elastically stored energy of protein gels, a range of gels were created from proteins from different origin (plant: pea and soy proteins, and animal: whey, blood plasma, egg white proteins, and ovalbumin) varying in network morphology set by the protein concentration, pH, ionic strength, or the presence of specific ions.

    The results showed that the observed positive and linear relation between water holding (WH) and elastically stored energy (RE) is generic for globular protein gels studied. The slopes of this relation are comparable for all globular protein gels (except for soy protein gels) whereas the intercept is close to 0 for most of the systems except for ovalbumin and egg white gels. The slope and intercept obtained allows one to predict the impact of tuning WH, by gel morphology or network stiffness, on the mechanical deformation of the protein-based gel. Addition of charged polysaccharides to a protein system leads to a deviation from the linear relation between WH and RE and this deviation coincides with a change in phase behavior.
    Activation energy of the disruption of gel networks in relation to elastically stored energy in fine-stranded ovalbumin gels
    Munialo, C.D. ; Linden, E. van der; Jongh, H.H.J. de - \ 2016
    Food Hydrocolloids 55 (2016). - ISSN 0268-005X - p. 163 - 171.
    Recoverable energy - network structure - disruption - ovalbumin - activation energy - fine-stranded
    The aim of this study was to relate the activation energy of the disruption of ovalbumin networks to elastically stored energy (i.e. recoverable energy, RE) obtained from mechanical deformation tests. To this end, heat-set ovalbumin gels were prepared at a fixed volume fraction and pH, but varying incubation temperatures. The activation energy required to disrupt the gels was derived from the Arrhenius equation. Increasing incubation temperature from 65 to 95 °C during gel formation resulted in a gradual increase in the activation energy up to a factor of ∼ 8. Gels obtained at or just below the protein denaturation temperature of around 75 °C had significantly lower recoverable energy (RE). These latter gels also had lower fracture stress and strain. At incubation temperatures above 70 °C RE was constant around 75 %, although a steady increase in activation energy was observed. This demonstrates that storing energy in a protein network is not directly related to the interactions that make up the network. A combination of electron microscopy, water holding, and stress relaxation experiments were performed to study the different energy dissipation modes. It was shown that different dissipation modes for various gels were comparable, and this explains why the RE was similar, with the exception of gels prepared at lower incubation temperatures where (micro) fracture events could have occurred that lowered the RE. These results suggest that RE is not a network characteristic related to microstructural or smaller length scale interactions, but the result of various material-related energy dissipation mechanisms.
    Relation between gel stiffness and water holding for coarse and fine-stranded protein gels
    Urbonaite, V. ; Kaaij, S. van der; Jongh, H.H.J. de; Scholten, E. ; Ako, K. ; Linden, E. van der; Pouvreau, L. - \ 2016
    Food Hydrocolloids 56 (2016). - ISSN 0268-005X - p. 334 - 343.
    Effective gel permeability coefficient - Effective water flux coefficient - Gel coarseness - Water holding - WPI gels - Young's modulus

    The sensory perception of foods is directly related to gel morphology. The aim of this research was to investigate the relationship between gel water holding and stiffness for gels with a different morphology. Whey protein gels were prepared by varying ionic strength to create fine and coarse-stranded gels. These gels were characterized for their coarseness, stiffness and their water holding capacity. Fine gels were referred to typical coarseness length scale smaller than 0.1 μm and coarse gels were referred to coarseness length scale larger than 0.1 μm. Water holding was measured both as a function of time and of applied pressure. Increased gel coarseness length scale in both fine and coarse gels resulted in a larger extent of network deformation at a certain applied force. For fine gels, the coarseness length scale of the gel was shown to determine water removal. In the case of coarse gels, coarseness length scale and stiffness had a counteracting effect, but coarseness length scale was still dominant. These results show that the tuning of coarseness length scale of protein networks independent of stiffness or, the other way round, provides a tool to set the water holding capacity in food gels.

    Effect of vitamin B12 and folic acid supplementation on biomarkers of endothelial function and inflammation among elderly individuals with hyperhomocysteinemia
    Dijk, S.C. van; Enneman, A.W. ; Swart, K.M.A. ; Wijngaarden, J.P. van; Ham, A.C. ; Jonge, R. ; Blom, H.J. ; Feskens, E.J.M. ; Geleijnse, J.M. ; Schoor, N.M. van; Dhonukshe-Rutten, R.A.M. ; Jongh, R.T. de; Lips, P. ; Groot, C.P.G.M. de; Uitterlinden, A.G. ; Meiracker, A.H. van den; Mattace-Raso, F.U.S. ; Velde, N. van der; Smulders, Y. - \ 2016
    Vascular Medicine 21 (2016)2. - ISSN 1358-863X - p. 91 - 98.
    B-vitamin trials failed to demonstrate beneficial effects on cardiovascular outcomes, but hyperhomocysteinemia still stands out as an independent cardiovascular risk factor, particularly in elderly individuals. B-vitamins may influence early vascular dysfunction, such as endothelial dysfunction, or may have adverse effects, for example on inflammation. We investigated the effect of B-vitamins on endothelial function and inflammation within an interventional study. This study was conducted within the framework of the B-PROOF trial, which included 2919 hyperhomocysteinemic elderly individuals, who received daily vitamin B12 (500 μg) and folic acid (400 μg) or placebo for 2 years. Using an electrochemiluminescence platform, we measured intercellular adhesion molecule 1 (ICAM-1), vascular adhesion molecule 1 (VCAM-1), serum amyloid A (SAA), vascular endothelial growth factor (VEGF) and C-reactive protein (CRP) at baseline and follow-up in a subsample of 522 participants (271 intervention group; 251 placebo). Treatment effects were analyzed with ANCOVA. The participants had a mean age of 72 years, and 55% of them were male. At the 2-year follow-up, B-vitamins did not change the ICAM-1 (+36% change in the intervention group versus +32% change in the placebo group; p = 0.72), VCAM-1 (+27% vs +25%; p = 0.39), VEGF (–1% vs +4%; p = 0.40), SAA (+34% vs +38%; p = 0.85) or CRP levels (+26% vs +36%; p = 0.70) as compared to placebo. In conclusion, in elderly patients with hyperhomocysteinemia, vitamin B12 and folic acid are unlikely to influence either endothelial function or low-grade systemic inflammation. ClinicalTrials.gov Identifier: NCT00696514
    Gelatin increases the coarseness of whey protein gels and impairs water exudation from the mixed gel at low temperatures
    Martin, A.H. ; Bakhuizen, E. ; Ersch, C. ; Urbonaite, V. ; Jongh, H.H.J. de; Pouvreau, L.A.M. - \ 2016
    Food Hydrocolloids 56 (2016). - ISSN 0268-005X - p. 236 - 244.
    Water holding - whey protein - gelatin - protein mixture - coarseness - gel stiffness
    To understand the origin of water holding of mixed protein gels, a study was performed on water exudation from mixed whey protein (WP)-gelatin gels upon applied pressure. Mixed gels were prepared with varying WP and gelatin concentration and gelatin type to obtain gels with a wide range of gel properties. Gels were characterized for their water holding (maximum of exuded water, Amax, and ease with which water can be exuded, k), gel coarseness (from CLSM image analysis) and gel stiffness (Young's modulus) at 20 and 40 °C, below and above the melting temperature of gelatin. Gelatin caused an increase in gel coarseness of the WP network, as induced by phase separation between WP and gelatin. The effect of gel coarseness and gel stiffness on Amax was found to be intertwined but above all, dictated by the gelatin concentration and gelatin network. At 20 °C, a transition point in gelatin concentration was observed above which stiffness surpassed coarseness in importance for Amax. Above this concentration, gelatin dominates the mechanical response of the mixed system. At 40 °C, when gelatin is melted, coarser and less stiff networks, as set by the WP network, lead to higher Amax. Tailoring of the coarseness and stiffness and therefore Amax and k, can be achieved by selective mixing in terms of protein concentrations, and type of gelatin. By varying gelatin type from A to B, altered phase behavior leads to gels with higher coarseness and lower stiffness but similar Amax.
    The effect of polysaccharides on the ability of whey protein gels to either store or dissipate energy upon mechanical deformation
    Munialo, C.D. ; Linden, E. van der; Ako, K. ; Nieuwland, M. ; As, H. van; Jongh, H.H.J. de - \ 2016
    Food Hydrocolloids 52 (2016). - ISSN 0268-005X - p. 707 - 720.
    The addition of polysaccharides to proteins during gel formation can alter the mechanical and textural properties of the resultant gels. However, the effect of addition of different polymers on mechanical properties of whey protein (WP) gels including their ability to elastically store energy, often measured in terms of the recoverable energy (RE), or dissipate energy, has not been fully reported. In this paper heat-induced WP gels containing high (HM) or low (LM) methylated negatively charged pectin or the neutral pullulan were prepared to study how the addition of polysaccharides to WP affects the mechanical properties of the formed gels. These gels were subjected to uniaxial compression and mechanical properties, including RE, were evaluated. The addition of pullulan to WP did not enhance the RE, whereas an increase in LM pectin resulted in higher RE. For gels containing HM pectin, the presence of the polymer induced an initial decrease of the RE. Nevertheless, RE increased with further increase in pectin concentration. These findings indicate that the addition of polysaccharides to whey proteins during gel formation results in changes in the RE but to different extent for different polymers. The results from this study suggest that the addition of polysaccharides to WP can be used as a tool to modulate the ability of whey protein gels to elastically store energy upon mechanical deformation.
    Arterial stiffness is not associated with bone parameters in an elderly hyperhomocysteinemic population
    Dijk, S.C. van; Jongh, R.T. de; Enneman, A.W. ; Ham, A.C. ; Swart, K.M.A. ; Wijngaarden, J.P. van; Zwaluw, N.L. van der; Brouwer-Brolsma, E.M. ; Schoor, N.M. van; Dhonukshe-Rutten, R.A.M. ; Lips, P. ; Groot, C.P.G.M. de; Smulders, Y.M. ; Blom, H.J. ; Feskens, E.J.M. ; Geleijnse, J.M. ; Meiracker, A.H. van den; Mattace Raso, F.U.S. ; Uitterlinden, A.G. ; Zillikens, M.C. ; Velde, N. van der - \ 2016
    Journal Bone Mineral Metabolism 34 (2016)1. - ISSN 0914-8779 - p. 99 - 108.
    Several studies have observed positive associations between bone disease and cardiovascular disease. A potential common pathway is hyperhomocysteinemia; however, to date, there is a lack of data regarding hyperhomocysteinemic populations. Therefore, we examined both cross-sectionally and longitudinally, whether there is an association between bone parameters and arterial stiffness in a hyperhomocysteinemic population, and investigated the potential common role of homocysteine (hcy) level on these associations. Cross-sectional and longitudinal data of the B-PROOF study were used (n = 519). At both baseline and 2-year follow-up we determined bone measures—incident fractures and history of fractures, bone-mineral density (BMD) and quantitative ultrasound (QUS) measurement. We also measured arterial stiffness parameters at baseline—pulse wave velocity, augmentation index and aortic pulse pressure levels with applanation tonometry. Linear regression analysis was used to examine these associations and we tested for potential interaction of hcy level. The mean age of the study population was 72.3 years and 44.3 % were female. Both cross-sectionally and longitudinally there was no association between arterial stiffness measures and BMD or QUS measurements or with incident fractures (n = 16) within the 2–3 years of follow-up. Hcy level did not modify the associations and adjustment for hcy did not change the results. Arterial stiffness was not associated with bone parameters and fractures, and hcy neither acted as a pleiotropic factor nor as a mediator. The potential association between bone and arterial stiffness is therefore not likely to be driven by hyperhomocysteinemia.
    The contribution of time-dependent stress relaxation in protein gels to the recoverable energy that is used as a tool to describe food texture
    Jong, S. de; Vliet, T. van; Jongh, H.H.J. de - \ 2015
    Mechanics of Time-Dependent Materials 19 (2015)4. - ISSN 1385-2000 - p. 505 - 518.
    Protein Network - Mechanical deformation - Energy dissipation - stress relaxation - Recoverable energy
    The recoverable energy (RE), defined as the ratio of the work exerted on a test specimen during compression and recovered upon subsequent decompression, has been shown to correlate to sensory profiling of protein-based food products. Understanding the mechanism determining the time-dependency of RE is primordial. This work aims to identify the protein-specific impact on the recoverable energy by stress dissipation via relaxation of (micro)structural rearrangements within protein gels. To this end, caseinate and gelatin gels are studied for their response to time-dependent mechanical deformation as they are known to develop structurally distinct network morphologies. This work shows that in gelatin gels no significant stress relaxation occurs on the seconds timescale, and consequently no time-dependency of the amount of energy stored in this material is observed. In caseinate gels, however, the energy dissipation via relaxation processes does contribute significantly to the time-dependency of reversible stored energy in the network. This can explain the obtained RE as a function of applied deformation at slow deformation rates. At faster deformation, an additional contribution to the dissipated energy is apparent, that increases with the deformation rate, which might point to the role of energy dissipation related to friction of the serum entrapped by the protein-network. This work shows that engineering strategies focused on controlling viscous flow in protein gels could be more effective to dictate the ability to elastically store energy in protein gels than routes that direct protein-specific aggregation and/or network-assembly.
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