Records 21 - 40 / 312
Sub-chronic toxicity study in rats orally exposed to nanostructured silica
Zande, M. van der; Vandebriel, R.J. ; Groot, M.J. ; Kramer, E.H.M. ; Herrera Riviera, Z.E. ; Rasmussen, K. ; Ossenkoppele, J.S. ; Tromp, P. ; Gremmer, E.R. ; Peters, R.J.B. ; Hendriksen, P.J. ; Marvin, H.J.P. ; Hoogenboom, L.A.P. ; Peijnenburg, A.A.C.M. ; Bouwmeester, H. - \ 2014
Particle and Fibre Toxicology 11 (2014). - ISSN 1743-8977
in-vivo biodistribution - expression profiles - liver fibrosis - nanoparticles - absorption - elimination - injection - foods - acid - size
Synthetic Amorphous Silica (SAS) is commonly used in food and drugs. Recently, a consumer intake of silica from food was estimated at 9.4 mg/kg bw/day, of which 1.8 mg/kg bw/day was estimated to be in the nano-size range. Food products containing SAS have been shown to contain silica in the nanometer size range (i.e. 5 – 200 nm) up to 43% of the total silica content. Concerns have been raised about the possible adverse effects of chronic exposure to nanostructured silica.
Compensation in Root Water Uptake Models Combined with Three-Dimensional Root Length Density Distribution
Heinen, M. - \ 2014
Vadose Zone Journal 13 (2014)2. - ISSN 1539-1663 - 9 p.
hydraulic architecture - integrated approach - porous-media - absorption - conductivity - systems - soils
A three-dimensional root length density distribution function is introduced that made it possible to compare two empirical uptake models with a more mechanistic uptake model. Adding a compensation component to the more empirical model resulted in predictions of root water uptake distributions similar to those predicted by the more complex model. Because root water uptake is a considerable component in the soil water balance, a lot of attention has been paid to defining and applying root water uptake models. These models can be grouped into empirical vs. mechanistic root uptake models. Intermodel comparisons are valuable in understanding the different concepts used. Such a comparison is sometimes difficult because the level of information required by the models is different, for example, information on the root length density distribution. Here a three-dimensional root length density distribution function is introduced that makes it possible to compare two empirical uptake models with a more mechanistic uptake model. Adding a compensation component to the more empirical model results in prediction of root water uptake distributions in the root zone similar to those predicted by the more complex model.
Minimizing measurement uncertainties of coniferous needle-leaf optical properties, part I: methodological review
Yanez Rausell, L. ; Schaepman, M.E. ; Clevers, J.G.P.W. ; Malenovsky, Z. - \ 2014
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 7 (2014)2. - ISSN 1939-1404 - p. 399 - 405.
revised measurement methodology - chlorophyll content estimation - radiative-transfer model - reflectance spectra - hyperspectral data - bifacial leaf - boreal forest - leaves - light - absorption
Optical properties (OPs) of non-flat narrow plant leaves, i.e., coniferous needles, are extensively used by the remote sensing community, in particular for calibration and validation of radiative transfer models at leaf and canopy level. Optical measurements of such small living elements are, however, a technical challenge and only few studies attempted so far to investigate and quantify related measurement errors. In this paper we review current methods and developments measuring optical properties of narrow leaves. We discuss measurement shortcomings and knowledge gaps related to a particular case of non-flat nonbifacial coniferous needle leaves, e.g., needles of Norway spruce (Picea abies (L.) Karst.).
Optimizing illumination in the greenhouse using a 3D model of tomato and a ray tracer
Visser, P.H.B. de; Buck-Sorlin, G.H. ; Heijden, G.W.A.M. van der - \ 2014
Frontiers in Plant Science 5 (2014). - ISSN 1664-462X - 7 p.
structural plant-model - light interception - cucumber canopies - photosynthesis - simulation - environment - absorption
Reduction of energy use for assimilation lighting is one of the most urgent goals of current greenhouse horticulture in the Netherlands. In recent years numerous lighting systems have been tested in greenhouses, yet their efficiency has been very difficult to measure in practice. This simulation study evaluated a number of lighting strategies using a 3D light model for natural and artificial light in combination with a 3D model of tomato. The modeling platform GroIMP was used for the simulation study. The crop was represented by 3D virtual plants of tomato with fixed architecture. Detailed data on greenhouse architecture and lamp emission patterns of different light sources were incorporated in the model. A number of illumination strategies were modeled with the calibrated model. Results were compared to the standard configuration. Moreover, adaptation of leaf angles was incorporated for testing their effect on light use efficiency (LUE). A Farquhar photosynthesis model was used to translate the absorbed light for each leaf into a produced amount of carbohydrates. The carbohydrates produced by the crop per unit emitted light from sun or high pressure sodium lamps was the highest for horizontal leaf angles or slightly downward pointing leaves, and was less for more upward leaf orientations. The simulated leaf angles did not affect light absorption from inter-lighting LED modules, but the scenario with LEDs shining slightly upward (20°) increased light absorption and LUE relative to default horizontal beaming LEDs. Furthermore, the model showed that leaf orientation more perpendicular to the string of LEDs increased LED light interception. The combination of a ray tracer and a 3D crop model could compute optimal lighting of leaves by quantification of light fluxes and illustration by rendered lighting patterns. Results indicate that illumination efficiency increases when the lamp light is directed at most to leaves that have a high photosynthetic potential. - See more at: http://journal.frontiersin.org/Journal/10.3389/fpls.2014.00048/abstract#sthash.oZ0vUtYM.dpuf
Energy from CO2 using capacitive electrodes – Theoretical outline and calculation of open circuit voltage
Par-Garcia, J.M. ; Schaetzle, O. ; Biesheuvel, P.M. ; Hamelers, H.V.M. - \ 2014
Journal of Colloid and Interface Science 418 (2014). - ISSN 0021-9797 - p. 200 - 207.
anion-exchange membranes - porous-electrodes - carbamate formation - aqueous-solution - acid anions - monoethanolamine - equilibrium - absorption - simulation - capture
Recently, a new technology has been proposed for the utilization of energy from CO2 emissions (Hamelers et al., 2014). The principle consists of controlling the dilution process of CO2–concentrated gas (e.g., exhaust gas) into CO2–dilute gas (e.g., air) thereby extracting a fraction of the released mixing energy. In this paper, we describe the theoretical fundamentals of this technology when using a pair of charge–selective capacitive electrodes. We focus on the behavior of the chemical system consisting of CO2 gas dissolved in water or monoethanolamine solution. The maximum voltage given for the capacitive cell is theoretically calculated, based on the membrane potential. The different aspects that affect this theoretical maximum value are discussed.
Assessing environmental consequences of using co-products in animal feed
Zanten, H.H.E. van; Mollenhorst, H. ; Vries, J.W. de; Middelaar, C.E. van; Kernebeek, H.R.J. van; Boer, I.J.M. de - \ 2014
The International Journal of Life Cycle Assessment 19 (2014)1. - ISSN 0948-3349 - p. 79 - 88.
bio-energy - digestion - impact - rumen - perspective - absorption - manure - tract - model
The livestock sector has a major impact on the environment. This environmental impact may be reduced by feeding agricultural co-products (e.g. beet tails) to livestock, as this transforms inedible products for humans into edible products, e.g. pork or beef. Nevertheless, co-products have different applications such as bioenergy production. Based on a framework we developed, we assessed environmental consequences of using co-products in diets of livestock, including the alternative application of that co-product. We performed a consequential life cycle assessment, regarding greenhouse gas emissions (including emissions related to land use change) and land use, for two case studies. Case 1 includes increasing the use of wheat middlings in diets of dairy cattle at the expense of using it in diets of pigs. The decreased use of wheat middlings in diets of pigs was substituted with barley, the marginal product. Case 2 includes increasing the use of beet tails in diets of dairy cattle at the expense of using it to produce bioenergy. During the production of biogas, electricity, heat and digestate (that is used as organic fertilizer) were produced. The decrease of electricity and heat was substituted with fossil fuel, and digestate was substituted with artificial fertilizer. Using wheat middlings in diets of dairy cattle instead of using it in diets of pigs resulted in a reduction of 329 kg CO2 eq per ton wheat middlings and a decrease of 169 m(2) land. Using beet tails in diets of dairy cattle instead of using it as a substrate for anaerobic digestion resulted in a decrease of 239 kg CO2 eq per ton beet tails and a decrease of 154 m(2) land. Emissions regarding land use change contributed significantly in both cases but had a high uncertainty factor, +/- 170 ton CO2 ha(-1). Excluding emissions from land use change resulted in a decrease of 9 kg CO2 eq for case 1 'wheat middlings' and an increase of 50 kg CO2 eq for case 2 'beet tails'. Assessing the use of co-products in the livestock sector is of importance because shifting its application can reduce the environmental impact of the livestock sector. A correct assessment of the environmental consequences of using co-products in animal feed should also include potential changes in impacts outside the livestock sector, such as the impact in the bioenergy sector.
Novel multi-sugar assay for site-specific gastrointestinal permeability analysis: A randomized controlled crossover trial
Wijck, K. van; Verlinden, T.J.M. ; Eijk, H.M.H. van; Dekker, J. ; Buurman, W.A. ; Dejong, C.H.C. ; Lenaerts, K. - \ 2013
Clinical Nutrition 32 (2013)2. - ISSN 0261-5614 - p. 245 - 251.
nonsteroidal antiinflammatory drugs - intestinal permeability - humans - mannitol - nsaid - indomethacin - absorption - lactulose - rat - enteropathy
Background & aims: Increased gastrointestinal (GI) permeability is an important hallmark of many conditions, potentially leading to antigen exposure and sepsis. Current permeability tests are hampered by analytical limitations. This study aims to compare the accuracy of our multi-sugar (MS) and the classical dual sugar (DS) test for detection of increased GI permeability. Methods: Ten volunteers received permeability analysis using MS (1 g sucrose, lactulose, sucralose, erythritol, 0.5 g rhamnose in water) or DS (5 g lactulose, 0.5 g rhamnose), after indomethacin or placebo. Blood and urine were analyzed by isocratic LC-MS. Results: MS testing revealed significantly elevated urinary lactulose/rhamnose (L/R) ratios after indomethacin, due to enhanced lactulose excretion (P <.01) and unaltered rhamnose excretion. The DS test showed increased L/R ratios, due to increased lactulose excretion and decreased rhamnose excretion (both P <.05). After indomethacin, plasma L/R increased in both assays (P <.05 and P <.01). Urinary and plasma L/R ratios correlated significantly. Indomethacin increased sucrose excretion and 0-1 h sucrose/rhamnose. Colon permeability was unchanged. Conclusions: Sensitive permeability analysis is feasible in plasma and urine using MS or DS test. In contrast to the DS test, monosaccharide excretion is not decreased by the MS test. In short, the MS test provides accurate, site-specific information on gastroduodenal, small, and large intestinal permeability. Registered at US National Library of Medicine (http://www.clinicaltrials.gov, NCT00943345). (C) 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
Simulation of the effect of maize porridge fortified with grain amaranth or micronutrient powder containing NaFeEDTA on iron intake and status in Kenyan children
Macharia-Mutie, C.W. ; Omusundi, A.M. ; Mwai, J.M. ; Mwangi, A.M. ; Brouwer, I.D. - \ 2013
Public Health Nutrition 16 (2013)9. - ISSN 1368-9800 - p. 1605 - 1613.
preschool-children - body iron - deficiency - absorption - anemia - women - trial - foods - biofortification - bioavailability
Objective: Simulating the probable impact of grain amaranth and highly absorbable, low-Fe micronutrient powder (MNP) on Fe status in a potential target population is an essential step in choosing and developing an appropriate actual intervention. Design: We simulated the potential effect of fortifying maize porridge with grain amaranth or MNP on the prevalence of inadequate Fe intake and Fe deficiency using data from two cross-sectional surveys. In the first survey (2008), dietary intake data were collected by two 24 h recalls (n 197). Biochemical data (n 70) were collected in the second survey (2010). A simulation with daily consumption for 80 d of non-fortified maize porridge (60 g of maize flour), amaranth-enriched porridge (80 g of grain amaranth-maize flour, 70: 30 ratio) or maize porridge fortified with MNP (2.5 mg Fe as NaFeEDTA) was done. Setting: Mwingi District, Kenya. Subjects: Pre-school children aged 12-23 months. Results: Prevalence of anaemia, Fe deficiency and Fe-deficiency anaemia was 49%, 46% and 24%, respectively. Consumption of non-fortified, amaranth-enriched and MNP-fortified maize porridge was estimated to provide a median daily Fe intake of 8.6 mg, 17.5 mg and 11.1 mg, respectively. The prevalence of inadequate Fe intake was reduced to 35% in the amaranth-enriched porridge group and 45% in the MNP-fortified porridge group, while ferritin concentration was increased in both (by 1.82 (95% CI 1.42, 2.34) mu g/l and 1.80 (95% CI 1.40, 2.31) mu g/l, respectively; P
Glucose and calcium ions may modulate the efficiency of bovine B-casomorphin-7 permeability through a monolayer of Caco-2 cells
Jarmolowska, B. ; Teodorowicz, M. ; Fiedorowicz, E. ; Sienkiewicz-Szlapka, E. ; Matysiewicz, M. ; Kostyra, E. - \ 2013
Peptides 49 (2013). - ISSN 0196-9781 - p. 59 - 67.
beta-casomorphin - opioid-peptides - tight junctions - endothelial permeability - intestinal permeability - gene-expression - transport - milk - absorption - iv
Milk and dairy products provide a lot of valuable nutritive elements. They are also sources of biologically active peptides, including ß-casomorphins that manifest the properties of morphine. An activity of DPPIV seems to be most crucial factor decreasing the efficiency of the ß-casomorphin-7 (BCM7) transport. The increase of BCM7 concentration in blood may intensify symptoms of apparent life threatening events (ALTE), autism, schizophrenia, and allergy. This study aimed at identifying the influence of several selected substances on a transport efficiency of bovine BCM7 through an intestinal monolayer in a Caco-2 cell model system. Applying the ELISA method, the permeability coefficient of BCM7 through the Caco-2 monolayer was calculated. TEER values were used to evaluate the integrity of Caco-2 cell monolayers. An increase of glucose and Ca(2+) concentrations in the culture medium was accompanied by an increase of the BCM7 transport efficiency. The lowest permeability coefficients of BCM7 were observed for the membranes with high electrical resistances. The transport was enhanced in the presence of milk infant formulas, whereas no changes were observed when using µ-opioid receptor antagonist (casoxin-6). The results may be useful in understanding the pathogenesis of inflammation and food allergy in infants.
Carbamate Stabilities of Sterically Hindered Amines from Quantum Chemical Methods: Relevance ofr CO2 Capture
Gangarapu, S. ; Marcelis, A.T.M. ; Zuilhof, H. - \ 2013
ChemPhysChem 14 (2013)17. - ISSN 1439-4235 - p. 3936 - 3943.
free-energy perturbations - carbon-dioxide - reaction-kinetics - aqueous-solutions - initio methods - absorption - 2-amino-2-methyl-1-propanol - methyldiethanolamine - monoethanolamine - technology
The influence of electronic and steric effects on the stabilities of carbamates formed from the reaction of CO2 with a wide range of alkanolamines was investigated by quantum chemical methods. For the calculations, B3LYP, M11-L, MP2, and spin-component-scaled MP2 (SCS-MP2) methods were used, coupled with SMD and SM8 solvation models. A reduction in carbamate stability leads to an increased CO2 absorption capacity of the amine and a reduction of the energy required for solvent regeneration. Important factors for the reduction of the carbamate stability were an increase in steric hindrance around the nitrogen atom, charge on the N atom and intramolecular hydrogen bond strength. The present study indicates that secondary ethanolamines with sterically hindering groups near the N atom show significant potential as candidates for industrial CO2-capture solvents.
Comparison of ileal and total tract nutrient digestibility of dry dog foods
Hendriks, W.H. ; Thomas, G. ; Bosch, G. ; Fahey, G.C. - \ 2013
Journal of Animal Science 91 (2013)8. - ISSN 0021-8812 - p. 3807 - 3814.
amino-acid-composition - endogenous nitrogen - reactive lysine - protein - pigs - diets - bioavailability - ingredients - absorption - intestine
The apparent total tract and ileal digestibility assays to measure AA absorption in commercial canine diets were compared in the present study. Five ileal cannulated dogs were fed 5 commercial dry canine foods selected to contain 19 to 30% CP in a 5 × 5 Latin square design. Ileal and total tract digestibility (apparent and standardized) of DM, OM, CP, crude fat (CF), carbohydrate, and AA (including reactive Lys) were calculated using Cr2O3 as an indigestible marker. Greater apparent total tract digestibility values were found for DM, OM, and CP (P = 0.034) compared with ileal digestibility values; however, CF (P = 0.058) had a greater ileal apparent digestibility. Apparent and standardized CP digestibility values were, respectively, 5.7 and 7.4 percentage units greater when measured over the total digestive tract compared with measurement at the ileum (P = 0.034 and 0.011, respectively). Ileal apparent digestibility for N of AA (P = 0.009) and most AA (P <0.05), except for Met, Ile, Lys, Phe, and Ala, was decreased if measured at the ileum. However, correction for endogenous losses showed only Met digestibility did not differ between measurement sites. Differences between sites in excess of 15 percentage units were recorded for AA. Apparent and standardized ileal reactive Lys digestibility was 3.1 to 15.3 percentage units greater than corresponding total tract digestibility values. For several indispensable AA, the bioavailability estimates currently used by the 2006 NRC and the 2011 Association of American Feed Control Officials to derive allowance estimates for canine adult maintenance were greater than the digestibility values of these AA in the commercial dog foods evaluated. Although the canine large intestine is relatively short, the total tract digestibility assay in dogs can overestimate the digestibility of dietary AA and CP and may not be an accurate method for the measurement of absorption. In this study, bioavailability estimates of AA appeared to be less than those used to derive allowance estimates for commercial dog foods. Further work is required if current recommendations warrant adjustment.
Investigating the Transport Dynamics of Anthocyanins from Unprocessed Fruit and Processed Fruit Juice from Sour Cherry (Prunus cerasus L.) across Intestinal Epithelial Cells
Toydemir, G. ; Boyacioglu, D. ; Capanoglu, E. ; Meer, I.M. van der; Tomassen, M.M.M. ; Hall, R.D. ; Mes, J.J. ; Beekwilder, J. - \ 2013
Journal of Agricultural and Food Chemistry 61 (2013)47. - ISSN 0021-8561 - p. 11434 - 11441.
red grape juice - protein interactions - cellular uptake - absorption - quercetin - dietary - caco-2 - bioavailability - consumption - glucosides
Anthocyanins can contribute to human health through preventing a variety of diseases. The uptake of these compounds from food and the parameters determining uptake efficiency within the human body are still poorly understood. Here we have employed a Caco-2 cell based system to investigate the transport of key antioxidant food components from sour cherry (Prunus cerasus L.) across the intestinal epithelial barrier. Anthocyanins and (-)-epicatechin were supplied in three contrasting matrices: fruit, processed fruit cherry juice, and polyphenolic fractions obtained by solid-phase extraction. Results show that both compound types behave differently. Fruit or juice matrices display comparable transport across the epithelial cell layer. The juice supplements sucrose and citric acid, which are regularly added to processed foods, have a positive effect on stability and transport. Polyphenolic fractions display a lower transport efficiency, relative to that of the fruit or juice, indicating the importance of food matrix components for intestinal absorption of polyphenols
Interpreting experimental data on egg production - applications of dynamic differential equations
France, J. ; Lopez, S. ; Kebreab, E. ; Dijkstra, J. - \ 2013
Poultry Science 92 (2013)9. - ISSN 0032-5791 - p. 2498 - 2508.
drosophila-melanogaster - gastrointestinal-tract - quantitative genetics - mathematical-models - phosphorus - calcium - absorption - fertility - algorithm
This contribution focuses on applying mathematical models based on systems of ordinary first-order differential equations to synthesize and interpret data from egg production experiments. Models based on linear systems of differential equations are contrasted with those based on nonlinear systems. Regression equations arising from analytical solutions to linear compartmental schemes are considered as candidate functions for describing egg production curves, together with aspects of parameter estimation. Extant candidate functions are reviewed, a role for growth functions such as the Gompertz equation suggested, and a function based on a simple new model outlined. Structurally, the new model comprises a single pool with an inflow and an outflow. Compartmental simulation models based on nonlinear systems of differential equations, and thus requiring numerical solution, are next discussed, and aspects of parameter estimation considered. This type of model is illustrated in relation to development and evaluation of a dynamic model of calcium and phosphorus flows in layers. The model consists of 8 state variables representing calcium and phosphorus pools in the crop, stomachs, plasma, and bone. The flow equations are described by Michaelis-Menten or mass action forms. Experiments that measure Ca and P uptake in layers fed different calcium concentrations during shell-forming days are used to evaluate the model. In addition to providing a useful management tool, such a simulation model also provides a means to evaluate feeding strategies aimed at reducing excretion of potential pollutants in poultry manure to the environment.
EURRECA—Estimating Zinc Requirements for Deriving Dietary Reference Values
Lowe, N.M.M. ; Dykes, F.C. ; Skinner, A.L. ; Patel, S. ; Warthon-Medina, M. ; Decsi, T. ; Fekete, K. ; Souverein, O.W. ; Dullemeijer, C. ; Cavelaars, A.J.E.M. ; Serra-Majem, L. ; Nissensohn, M. ; Bel, S. ; Moreno, L.A. ; Hermoso, M. ; Vollhardt, C. ; Berti, C. ; Cetin, I. ; Gurinovic, M. ; Novakovic, R.N. ; Harvey, L.J. ; Collings, R. ; Hall-Moran, V. - \ 2013
Critical Reviews in Food Science and Nutrition 53 (2013)10. - ISSN 1040-8398 - p. 1110 - 1123.
current micronutrient recommendations - coronary-artery-disease - lung-cancer - serum zinc - genetic-polymorphism - stable-isotope - old patients - absorption - phytate - copper
Zinc was selected as a priority micronutrient for EURRECA, because there is significant heterogeneity in the Dietary Reference Values (DRVs) across Europe. In addition, the prevalence of inadequate zinc intakes was thought to be high among all population groups worldwide, and the public health concern is considerable. In accordance with the EURRECA consortium principles and protocols, a series of literature reviews were undertaken in order to develop best practice guidelines for assessing dietary zinc intake and zinc status. These were incorporated into subsequent literature search strategies and protocols for studies investigating the relationships between zinc intake, status and health, as well as studies relating to the factorial approach (including bioavailability) for setting dietary recommendations. EMBASE (Ovid), Cochrane Library CENTRAL, and MEDLINE (Ovid) databases were searched for studies published up to February 2010 and collated into a series of Endnote databases that are available for the use of future DRV panels. Meta-analyses of data extracted from these publications were performed where possible in order to address specific questions relating to factors affecting dietary recommendations. This review has highlighted the need for more high quality studies to address gaps in current knowledge, in particular the continued search for a reliable biomarker of zinc status and the influence of genetic polymorphisms on individual dietary requirements. In addition, there is a need to further develop models of the effect of dietary inhibitors of zinc absorption and their impact on population dietary zinc requirements.
Role of surface charge in bioavailability and biodistribution of tri-block copolymer nanoparticles in rats after oral exposure
Bhattacharjee, S. ; Marcelis, A.T.M. ; Zuilhof, H. ; Woutersen, R.A. ; Rietjens, I.M.C.M. ; Alink, G.M. - \ 2013
Toxicology Research 2 (2013)3. - ISSN 2045-452X - p. 187 - 192.
silicon nanoparticles - gold nanoparticles - polystyrene particles - fischer-344 rats - cellular uptake - drug-delivery - in-vivo - cytotoxicity - toxicity - absorption
Tri-block copolymer nanoparticles (TCNP) are increasingly utilized, especially in drug delivery and diagnostics platforms. From in vitro studies, surface charge was observed to influence the transport of TCNP across the Caco-2 monolayers grown on transwell inserts. The objective of this study was to investigate the influence of surface charge on bioavailability and biodistribution of TCNP after oral exposure in vivo and to compare with the in vitro data. To attain the set objectives, monodisperse (45 ± 5 nm), fluorescent and differently charged (positive and negative) TCNP were orally administered to inbred Fischer 344 rats. Blood samples were collected at t = 0, 1/2, 1, 2, 4 and 6 h followed by sacrifice of the animals and collection of the major organs (lungs, liver, kidney, spleen, brain, intestine, and tibia). Quantitative assessments of TCNP in blood and organs were performed by fluorescence measurements. TCNP of both surface charges got absorbed and appeared in the blood within 1/2 h of oral administration. No significant difference in bioavailability and biodistribution could be found between positive and negative TCNP. Both the TCNP, irrespective of charge, showed major accumulation in the liver, kidneys and spleen, were detected in the brain and did not cause any significant increase in the serum alkaline phosphatase levels. Contrary to the in vitro data, surface charge was not found to influence the in vivo bioavailability and biodistribution of TCNP after oral exposure. The obtained results encourage further development of such TCNP, especially for drug delivery purposes.
Effect of algae- and silt concentration on clearance- and growth rate of the razor clam Ensis directus, Conrad
Kamermans, P. ; Brummelhuis, E.B.M. ; Dedert, M. - \ 2013
Journal of Experimental Marine Biology and Ecology 446 (2013). - ISSN 0022-0981 - p. 102 - 109.
acclimated digestive responses - suspended bottom material - cerastoderma-edule l. - mytilus-edulis - particle selection - feeding bivalves - food quality - absorption - filtration - mussel
Laboratory experiments were carried out with Ensis directus to estimate clearance rate and growth rate as a function of the amount of food and presence of silt. Two food levels were tested: low food availability (6.5 µg chla/l) and high food availability (16.5 µg chla/l) at four silt concentrations (0, 50, 150 and 300 mg/l). Clearance rates of E. directus varied between 0.7 and 5.9 l/h/g DW. At a silt concentration of 300 mg/l clearance rates were significantly lower (16–56%) than rates at 150 mg/l, 50 mg/l and 0 mg/l silt. This indicates that only the highest silt concentration induced a reduction in clearance rate. The tested food levels did not influence the clearance rate of E. directus. Maximum growth rate of E. directus was 0.24 mm increase in shell length and 2% increase in wet weight per day. Long-term (10 weeks) exposure to silt concentrations of 300 mg/l showed significantly higher growth than the 150 mg/l treatment. This indicates that exposure to a high silt concentration did not induce a reduction in growth, but stimulated growth. Long-term (10 weeks) exposure to a food level of 6.5 µg chla per litre reduced the shell growth of E. directus with 40% compared to growth at 16.5 µg chla per litre. The laboratory experiments suggest that E. directus is more sensitive to a reduction in algal concentration than to an increase in silt concentration.
Isoenergetic Replacement of Fat by Starch in Diets for African Catfish (Clarias gariepinus): Effect on Water Fluxes in the Gastro Intestinal Tract
Harter, T.S. ; Verreth, J.A.J. ; Heinsbroek, L.T.N. ; Schrama, J.W. - \ 2013
PLoS ONE 8 (2013)2. - ISSN 1932-6203
rainbow-trout - salmo-gairdneri - single meal - in-vivo - absorption - drinking - feed - eels - dry
The effect of an isoenergetic replacement of dietary fat by starch, on chyme characteristics and water fluxes in the gastro intestinal tract (GIT) was assessed. Adult African catfish (Clarias gariepinus) were fed a starch (SD) or fat (FD) diet and groups of fish were dissected at 2, 5 and 8 h after the consumption of a single meal. Chyme was collected quantitatively and was analysed for osmolality and dry matter (DM) content. Postprandial water fluxes were calculated, while using yttrium oxide (Y2O3) as an inert marker to account for the absorption of DM along the GIT. The largest differences in chyme characteristics between diets were observed in the stomach and decreased towards subsequent compartments. A high initial osmotic pressure was measured in the stomach for both diets (up to 49862 mOsm kg21) and was likely the driver for the endogeneous water influx to this compartment. Large additions of water were recorded to the stomach and proximal intestine for both diets and absorption of water took place in the mid- and distal intestine. Interestingly, the dietary treatment had an impact on water balance in the stomach and proximal intestine of the fish, but not in the mid- and distal intestine. A strong complementary relationship suggested that 59% of the water fluxes in the proximal intestine could be explained by previous additions to the stomach. Therefore, a higher dietary inclusion of starch led to a shift in water additions from the proximal intestine to the stomach. However, the sum of water additions to the GIT was not different between diets and was on average 6.5260.85 ml water g21 DM. The interactions between osmoregulation and digestion, in the GIT of fed freshwater fish, deserve further attention in future research.
Retrieval of spruce leaf chlorophyll content from airborne image data using continuum removal and radiative transfer
Malenovsky, Z. ; Homolova, L. ; Zurita-Milla, R. ; Lukes, P. ; Kaplan, V. ; Hanus, J. ; Gastellu-Etchegorry, J.P. ; Schaepman, M.E. - \ 2013
Remote Sensing of Environment 131 (2013). - ISSN 0034-4257 - p. 85 - 102.
canopy reflectance models - optical-properties model - area index - hyperspectral data - forest canopies - precision agriculture - vegetation canopies - red - band - absorption
We investigate combined continuum removal and radiative transfer (RT) modeling to retrieve leaf chlorophyll a & b content (Cab) from the AISA Eagle airborne imaging spectrometer data of sub-meter (0.4 m) spatial resolution. Based on coupled PROSPECT-DART RT simulations of a Norway spruce (Picea abies (L.) Karst.) stand, we propose a new Cab sensitive index located between 650 and 720 nm and termed ANCB650–720. The performance of ANCB650–720 was validated against ground-measured Cab of ten spruce crowns and compared with Cab estimated by a conventional artificial neural network (ANN) trained with continuum removed RT simulations and also by three previously published chlorophyll optical indices: normalized difference between reflectance at 925 and 710 nm (ND925&710), simple reflectance ratio between 750 and 710 nm (SR750/710) and the ratio of TCARI/OSAVI indices. Although all retrieval methods produced visually comparable Cab spatial patterns, the ground validation revealed that the ANCB650–720 and ANN retrievals are more accurate than the other three chlorophyll indices (R2 = 0.72 for both methods). ANCB650–720 estimated Cab with an RMSE = 2.27 µg cm- 2 (relative RRMSE = 4.35%) and ANN with an RMSE = 2.18 µg cm- 2 (RRMSE = 4.18%), while SR750/710 with an RMSE = 4.16 µg cm- 2 (RRMSE = 7.97%), ND925&710 with an RMSE = 9.07 µg cm- 2 (RRMSE = 17.38%) and TCARI/OSAVI with an RMSE = 12.30 µg cm- 2 (RRMSE = 23.56%). Also the systematic RMSES was lower than the unsystematic one only for the ANCB650–720 and ANN retrievals. Our results indicate that the newly proposed index can provide the same accuracy as ANN except for Cab values below 30 µg cm- 2, which are slightly overestimated (RMSE = 2.42 µg cm- 2). The computationally efficient ANCB650–720 retrieval provides accurate high spatial resolution airborne Cab maps, considerable as a suitable reference data for validating satellite-based Cab products.
Improving the Capture of Co2 by Substituted Monoethanolamines: Electronic Effects of Fluorine and Methyl Substituents
Gangarapu, S. ; Marcelis, A.T.M. ; Zuilhof, H. - \ 2012
ChemPhysChem 13 (2012)17. - ISSN 1439-4235 - p. 3973 - 3980.
main-group thermochemistry - free-energy perturbations - gas-phase basicities - ab-initio - noncovalent interactions - carbon-dioxide - amines - molecules - absorption - accuracy
The influence of electronic and steric effects on the reaction between CO(2) and monoethanolamine (MEA) absorbents is investigated using computational methods. The pK(a) of the alkanolamine, the reaction enthalpy for carbamate formation, and the hydrolytic carbamate stability are important factors for the efficiency of CO(2) capture. The steric and electronic effects of CH(3), CH(2)F, CHF(2), CF(3), F, dimethyl, difluoro, and bis(2-trifluoromethyl) substituents at the a carbon of MEA on this reaction are investigated. Density functional theory (DFT) (B3LYP, M06-2X, M08-HX and M11-L) and ab initio methods [spin component-scaled second-order Møller-Plesset theory (SCS-MP2), G3], each coupled with solvent models [conductor-like polarizable continuum model (CPCM) and universal solvation models (SM8 and SMD)], are shown to yield accurately calculated pK(a) values of the substituted MEAs. Specifically, G3, SCS-MP2, and M11-L methods coupled with the SMD and SM8 solvation models perform well with a mean unsigned error (MUE) of only 0.15, 0.24 and 0.25 pK(a) units, respectively. SCS-MP2 is used to calculate the reaction enthalpy for carbamate formation and the carbamate stability towards hydrolysis. With the introduction of ß-fluoro substituents (especially the CH(2) F moiety) the reaction enthalpy for the formation of carbamates can be fine-tuned to be less exothermic than that using the unsubstituted MEA. This implies a reduced energy requirement for the solvent-regeneration step in the post-combustion carbon-capture method, which is currently the energy-limiting step in efficient CO(2) capture. ß-Fluoro-substituted MEAs are also shown to form less stable carbamates than MEA. Thus, ß-fluoro-substituted MEAs display a great potential for the use in the post-combustion carbon-capture process. Finally, a clear correlation is observed between the gas-phase basicity and the tendency to form carbamates. This allows for the rapid prediction of which species will be formed experimentally, and thus the CO(2)-absorbing capacities of alkanolamines can be estimated
Changes in dietary macronutrient profile do not appear to affect endogenous urinary oxalate excretion in healthy adult cats
Dijcker, J.C. ; Hagen-Plantinga, E.A. ; Hendriks, W.H. - \ 2012
The Veterinary Journal 194 (2012)2. - ISSN 1090-0233 - p. 235 - 239.
clinically normal cats - subcellular-distribution - feline uroliths - calcium - glyoxylate - protein - hydroxyproline - canine - metabolism - absorption
The progressive increase in calcium oxalate uroliths reported in cats diagnosed with urolithiasis may partly be due to changes in nutrition. Since cats have a predominant mitochondrial alanine:glyoxylate aminotransferase 1 (AGT1) location, high carbohydrate intake may induce endogenous oxalate synthesis. This hypothesis was tested by feeding 12 adult, female cats three diets differing in macronutrients, namely, high protein (HP), high carbohydrate (HC) and high fat (HF), using a randomised Latin square design in a 36-day study. In addition to plasma, urine was collected quantitatively using modified litter boxes. A pilot study with four cats, conducted to determine the adaptation time of urinary oxalate (Uox) excretion to a dietary change, indicated a mean (±SEM) adaptation time of 5.9 ± 0.7 days, with the urinary oxalate:creatinine (Ox:Cr) ratio increasing from 36.1 ± 3.7 to 81.6 ± 2.3 mmol/mol. In the main study, plasma oxalate concentration was significantly lower when feeding the HP compared to the HF (P = 0.003) diet, whereas Uox excretion (µmol/kg BW0.75/day) and the urinary Ox:Cr ratio were unaffected by diet. The Uox concentration (mmol/L) was significantly lower when feeding the HP compared to the HC (P = 0.004) and HF (P = 0.001) diets. The results indicate that changes in macronutrient profile may not influence endogenous Uox excretion in cats but high dietary protein did reduce Uox concentration and may therefore help to lower the risk of calcium oxalate formation.