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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    A systematic evaluation of Flow Field Flow Fractionation and single-particle ICP-MS to obtain the size distribution of organo-mineral iron oxyhydroxide colloids
    Moens, Claudia ; Waegeneers, Nadia ; Fritzsche, Andreas ; Nobels, Peter ; Smolders, Erik - \ 2019
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1599 (2019). - ISSN 0021-9673 - p. 203 - 214.
    Flow Field Flow Fractionation - Multimethod comparison - Organo-mineral iron oxyhydroxide colloids - Particle size distribution - Single-particle inductively coupled plasma-mass spectrometry - Triple quadrupole mass spectrometry

    Colloidal iron(III)oxyhydroxides (FeOx)are important reactive adsorbents in nature. This study was set up to determine the size of environmentally relevant FeOx colloids with new methods, i.e. Flow Field Flow Fractionation (FlFFF-UV-ICP-MS)and single-particle ICP-MS/MS (sp-ICP-MS)and to compare these with standard approaches, i.e. dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), microscopy (TEM), membrane filtration, centrifugation and dialysis. Seven synthetic nano- and submicron FeOx with different mineralogy and coating were prepared and two soil solutions were included. The FlFFF was optimized for Fe recovery, yielding 70–90%. The FlFFF determines particle size with high resolution in a 1 mM NH 4 HCO 3 (pH 8.3)background and can detect Fe-NOM complexes <5 nm and organo-mineral FeOx particles ranging 5–300 nm. The sp-ICP-MS method had a size detection limit for FeOx of about 32–47 nm. The distribution of hydrodynamic diameters of goethite particles detected with FlFFF, NTA and DLS were similar but the values were twice as large as the Fe cores of particles detected with sp-ICP-MS and TEM. Conventional fractionation by centrifugation and dialysis generally yielded similar fractions as FlFFF but membrane filtration overestimated the large size fractions. Particles formed from Fe(II)oxidation in the presence of NOM showed strikingly smaller organo-mineral Fe-Ox colloids as the NOM/Fe ratio increased. The soil solution obtained with centrifugation of an acid peat was dominated by small (<30 nm)Fe-OM complexes and organo-mineral FeOx colloids whereas that of a mineral pH neutral soil mainly contains larger (30–200 nm)Fe-rich particles. The FlFFF-UV-ICP-MS is recommended for environmental studies of colloidal FeOx since it has a wide size detection range, it fractionates in an environmentally relevant background (1 mM NH 4 HCO 3 )and it has acceptable element recoveries.

    Development and Validation of a Method for the Detection of Titanium Dioxide Particles in Human Tissue with Single Particle ICP-MS
    Peters, Ruud ; Undas, Anna ; Memelink, Joost ; Bemmel, Greet Van; Munniks, Sandra ; Bouwmeester, Hans ; Nobels, Peter ; Schuurmans, Wobbe ; Lee, Martijn Van Der - \ 2018
    Current Trends in Analytical and Bioanalytical Chemistry 2 (2018)1. - ISSN 2642-4266
    Human biomonitoring studies to determine total titanium (total-Ti) and titanium dioxide (TiO2) particles require very sensitive inductively coupled plasma high resolution mass spectrometry (ICP-HRMS) methods. The result of such studies can only be reliably when used in a risk assessment if the analytical methods are fully validated, as reported here for human liver and spleen. For total-Ti an acidic HNO3/HF digestion was applied, followed by ICP-HRMS analysis of the acidic digests. For TiO2 particles a two-step digestion procedure was developed. In the first step the formaldehyde-fixed tissue was depolymerized and in the second step an enzymatic digestion was performed. Sample digests were analyzed with ICP-HRMS operated in single particle mode to detect TiO2 particles. Both methods were validated according to NEN 7777 using a scheme of duplicate analysis over an eight day period. Detection limits for total-Ti and TiO2 particles were 0.01 and 0.005 mg Ti/kg with a particle size quantification limit of 85 nm for TiO2 particles. Repeatability and reproducibility were 24% and 31% for the total titanium concentration, 22% and 39% for the particle titanium concentration, and 29% and 24% for the titanium dioxide particle size. In total 30 human tissue samples were analyzed with the developed and validated method. The results show a total-Ti content in the range of 0.02-0.09 mg Ti/kg in liver and 0.02-0.4 mg Ti/kg in spleen. The concentrations of particle TiO2 ranged from 0.01-0.08 mg Ti/kg in liver and from 0.01-0.1 mg Ti/kg in spleen. On the average, particle TiO2 explained up to 67% of the total-Ti concentrations. The detected TiO2 particles had a particle size range of 85 to 720 nm.
    Effects of monounsaturated fatty acids versus complex carbohydrates on serum lipoproteins and apoproteins in healthy men and women.
    Mensink, R.P. ; Groot, M.J.M. de; Broeke, L.T. van den; Severijnen-Nobels, A.P. ; Demacker, P.N.M. ; Katan, M.B. - \ 1989
    Metabolism : Clinical and Experimental 38 (1989). - ISSN 0026-0495 - p. 172 - 178.
    The effects of a high-carbohydrate, high-fiber diet and an olive-oil-rich diet on the distribution of cholesterol over the various lipoproteins, on serum apolipoproteins, and on the composition of HDL2 and HDL3 were studied under strict dietary control. Forty-eight healthy subjects first consumed a high-saturated-fat diet [proportion of energy, en%] (saturated fat 20 en%, total fat 38 en%) for 17 days. For the next 36 days, 24 subjects consumed a diet high in complex carbohydrates (monounsaturated fat 9 en%, total fat 22 en%) and the other 24 consumed a high-fat, olive-oil-rich diet (monounsaturated fat 24 en%, total fat 41 en%). The amounts of protein (12% to 14 en%), polyunsaturated fat (4 to 5 en%), and cholesterol (31 to 35 mg/MJ) were similar in all three diets. Serum cholesterol levels fell by 0.44 mmol/L in subjects consuming the carbohydrate diet and by 0.52 mmol/L for those receiving the olive-oil-rich diet. VLDL-cholesterol levels rose by 0.08 mmol/L in the carbohydrate group and fell by 0.08 mmol/L in the olive oil group (P < .05 for difference between test diets). HDL2 and LDL cholesterol levels fell to the same extent on both diets. HDL3 cholesterol fell by 0.09 mmol/L on the high-carbohydrate diet and increased by 0.01 mmol/L on the olive oil diet (P < .05). There was no change in the composition of HDL3, suggesting that the fall was due to a decrease in the total number of circulating particles. Thus, Keys formula, which predicts no change in serum cholesterol when carbohydrate is replaced by oleic acid, holds for LDL but not for VLDL and HDL, which change in opposite directions. Apolipoprotein (apo) A-I levels decreased by 102 mg/L in the carbohydrate group and rose by 26 mg/L in the olive oil group (P < .05). For apo B these values were 5 mg/L and −83 mg/L, respectively. The apo A-I to apo B ratio decreased by 0.12, or 10%, on the carbohydrate diet and increased by 0.19, or 16%, on the olive oil diet (P < .01). It is concluded that the lipoprotein risk profile for coronary heart disease was affected more favorably by the olive-oil-rich diet than by the diet high in complex carbohydrates.
    Effect van olijfolie op het totaalserum- en HDL-cholesterolgehalte bij gezonde mensen.
    Mensink, R.P. ; Severijnen-Nobels, A.P. ; Vries, J.H.M. de; Katan, M.B. - \ 1988
    Voeding 49 (1988)6. - ISSN 0042-7926 - p. 138 - 142.
    koolhydraten - cholesterol - vet - vetten - voedselhygiëne - voeding - olijfolie - carbohydrates - cholesterol - fat - fats - food hygiene - nutrition - olive oil
    De resultaten van een voedingsexperiment zijn besproken. Het vervangen van verzadigde vetten door vetten met enkelvoudig onverzadigde vetzuren kan van betekenis zijn voor de preventie van hart- en vaatziekten.
    Methods for controlling nutrient intake in large-scale trials using natural mixed solid diets.
    Vries, J.H. de; Severijnen-Nobels, A. - \ 1988
    In: Abstract 10ieme Congr. Int. Dietetique, Paris (1988)
    Methods for controlling nutrient intake in large-scale trials using natural mixed solid foods.
    Vries, J.H.M. de; Severijnen-Nobels, A.P. - \ 1988
    In: Proc. 10th Int. Congr. Dietetics: Dietetics in the 90s, role of the dietician/nutritionist, M.F. Moyal (ed.). John Libbey, London - p. 91 - 94.
    Congruence of individual responsiveness to dietary cholesterol and to saturated fat in man.
    Katan, M.B. ; Berns, M.A.M. ; Glatz, J.F.C. ; Knuiman, J.T. ; Nobels, A. ; Vries, J.H.M. de - \ 1988
    Journal of Lipid Research 29 (1988). - ISSN 0022-2275 - p. 883 - 892.
    Previous experiments have shown that differences between humans in the response of serum cholesterol to dietary cholesterol are at least partly reproducible and stable over a prolonged period. In this study it was investigated whether enhanced sensitivity to dietary cholesterol and saturated fat go together. The subjects had also participated in three or four experiments dealing with the reproducibility of the effect on blood cholesterol of either adding cholesterol to the diet in normal subjects (NORM-EGG group; n = 23) or of cessation of egg consumption in subjects with a high habitual egg intake (HAB-EGG group; n = 24). In the present experiment the NORM-EGG subjects were fed a mixed natural diet providing 21% of energy as polyunsaturated and 11% as saturated fat (P/S2 ratio, 1.9) for 3 weeks, and one providing 5% of energy as polyunsaturated fat and 23% as saturated fat (P/S ratio, 0.2) for the next 3 weeks. The HAB-EGG group was fed the same diets in reverse order. The serum cholesterol concentrations were higher on the low P/S diet than on the high P/S diet (on average 23% in normal subjects and 16% in habitual egg eaters). The correlation coefficient between each subject's serum cholesterol response to fatty acids and his or her average response to dietary cholesterol in the dietary cholesterol experiments was 0.62 for the normal subjects (P less than 0.01) and 0.15 for the HAB-EGG group. We conclude that modest differences in responsiveness of serum cholesterol to dietary saturated fat do exist in humans, and that, in people of normal cholesterol intake, responsiveness to dietary cholesterol and to saturated fat tend to go together.
    Hyperresponsiveness of serum cholesterol to dietary cholesterol and dietary fatty acids in humans and rabbits.
    Glatz, J.F.C. ; Berns, M.A.M. ; Vries, J. de; Nobels, A. ; Beynen, A.C. ; Katan, M.B. - \ 1986
    European Journal of Clinical Investigation 16 (1986). - ISSN 0014-2972 - p. A54 - A54.
    Existence of consistent hypo- and hyperresponders to dietary cholesterol in man.
    Katan, M.B. ; Beynen, A.C. ; Vries, J.H.M. de; Nobels, A. - \ 1986
    American Journal of Epidemiology 123 (1986). - ISSN 0002-9262 - p. 221 - 234.
    Human hyper- and non-responders to dietary cholesterol: Do they exist?
    Katan, M.B. ; Beynen, A.C. ; Vries, J.H.M. de; Nobels, A. - \ 1985
    In: Proc. 4th European Nutrition Conf., E.M.E. van den Berg, W. Bosman en B.C. Breedveld (eds.). Voorlichtingsbureau voor de Voeding - p. 251 - 251.
    Characteristics of human hypo- and hyper-responders to dietary cholesterol
    Katan, M.B. ; Beynen, A.C. ; Vries, J. de; Nobels, A. ; Berns, M.A.M. ; Glatz, J.F.C. - \ 1985
    Circulation 72 (1985)Suppl. III. - ISSN 0009-7322 - p. 118 - 118.
    Human hyper- and non-responders to dietary cholesterol: do they exist?
    Katan, M.B. ; Beynen, A.C. ; Vries, J.H.M. de; Nobels, A. - \ 1983
    In: Abstr. comm. 4th European Nutrition Conf., Amsterdam, 1983, 119, ook in: CVD Epidemiology Newsletter (American Heart Association) 34 - p. 100 - 101.
    Towards an improved lipid-lowering diet: Additive effects of changes in nutrient intake
    Lewis, B. ; Katan, M.B. ; Merkx, Xi. ; Miller, N.E. ; Hammett, F. ; Kay, R.M. ; Nobels, A. ; Swan, A.V. - \ 1981
    The Lancet (1981)ii. - ISSN 0140-6736 - p. 1310 - 1313.
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