|0046 - Organoids as models to study probiotics
Hee, B. van der; Loonen, L.M.P. ; Taverne, N. ; Taverne-Thiele, J.J. ; Smidt, H. ; Wells, J.M. - \ 2019
- 1 p.
permeability - intestinal models - organoids - stem-cells - tight-junctions
For decades, scientists have exploited cancer cell lines as models to study host-pathogen interactions and intestinal functions in vitro. Such monotypic cell models have led to important discoveries but have notable limitations. Immortalized cell lines display biological variations such as aneuploidy, chromosome rearrangements or mutations leading to poorly reproducible results, even for the same cell line.
Organoids are gaining considerable interest as alternative models of the intestine due to their close resemblance to structural, cellular and functional complexity found in vivo. However, the three-dimensional geometry of stem-cell derived intestinal organoids limits easy access to the apical epithelium for investigating the influence of probiotics, bioactive and toxic compounds on barrier function and permeability. Here we present a new robust method for generating confluent intestinal cell monolayers from single-cell suspensions of enzymatically-dissociated organoids. Confluent polarised monolayers containing tight-junctions were formed in three days and could be used in experiments for up to two weeks. Multilineage differentiation of the ileal stem cells was demonstrated by immunohistochemistry, and RT-qPCR of cell-specific transcripts. Furthermore, we showed that adult stem-cell derived ileal organoids maintain location-specific transcriptional programs during long-term in vitro culture.
Permeation of probe molecules into alginate microbeads: Effect of salt and processing
Leusden, P. van; Hartog, G.J.M. den; Bast, A. ; Postema, M. ; Linden, E. van der; Sagis, L.M.C. - \ 2017
Food Hydrocolloids 73 (2017). - ISSN 0268-005X - p. 255 - 261.
Alginate beads - permeability - Microbeads - Debye length - salt concentration
The ability to exclude harmful factors from a hydrogel microbead is important for the degree of protection the beads offers to what is encapsulated within. The permeability of alginate microbeads, prepared by water-in-oil emulsification, was investigated by their ability to exclude FITC-labelled protein probes. The influence of alginate concentration, calcium concentration and method of addition, and salt content of the environment was investigated. The permeability was also compared to the permeability of beads made by the traditional method of dripping an alginate solution into a CaCl2 solution. Beads produced with low amounts of CaCl2 show a significant degree of swelling and are therefore very permeable (C/C0 (BSA) = 0.62, where C is the final concentration of BSA-FITC in the bead, and C0 the concentration of BSA-FITC in the continuous phase). With additional calcium, either by adding more calcium crystals after the emulsification step or by washing with a CaCl2 solution, beads swell less and are less permeable (C/C0 (BSA) = 0.13 and 0.12). Beads made by dripping are very permeable (C/C0 (BSA) ∼ 0.60). Because in this process the droplets of alginate are not constrained by a water-oil boundary, the beads can swell during gelation. The salt concentration in the continuous phase influences the strength of the electrostatic repulsion between the probes and the alginate network and hence affects the permeation of the probes into the beads. In the absence of salt, even FITC (389Da) is mostly excluded from the interior of the beads (C/C0 (FITC) ∼ 0.09).
Dermal absorption and toxicological risk assessment : pitfalls and promises
Buist, H. - \ 2016
Wageningen University. Promotor(en): Ruud Woutersen; Ivonne Rietjens, co-promotor(en): J.J.M. van de Sandt. - Wageningen : Wageningen University - ISBN 9789462577275 - 200
skin - absorption - permeability - in vitro - experiments - exposure assessment - risk assessment - toxicology - biocides - rodenticides - preservatives - disinfection - huid - absorptie - permeabiliteit - in vitro - experimenten - blootstellingsbepaling - risicoschatting - toxicologie - biociden - rodenticiden - conserveermiddelen - desinfectie
Absorption of toxic substances via the skin is an important phenomenon in the assessment of the risk of exposure to these substances. People are exposed to a variety of substances and products via the skin, either directly or indirectly, while at work, at home or in public space. Pesticides, organic solvents and metalworking fluids are seen to be important contributors to adverse health effects due to occupational exposure via the skin. In daily life, cosmetics, clothing and household products are the most relevant commodities with respect to exposure via the skin.
Given the importance of skin exposure in the assessment of the risk of toxic substances, the objective of this thesis was to further develop, evaluate and improve methods for including skin absorption data this assessment.
In this thesis, four factors influencing dermal absorption, namely dermal loading (chapters 3 and 6), irritative/corrosive potential (chapters 3 and 4), frequency of exposure (chapters 3, 4 and 5) and the vehicle used (chapter 5), were investigated in more detail. Furthermore, a model to extrapolate infinite dose absorption data to finite dose conditions, baptized Dermal Absorption Model for Extrapolation (DAME), was developed and tested.
n chapter 2 of this thesis, the relationship between relative dermal absorption and dermal loading was investigated. Hundred-and-thirty-eight dermal publicly available absorption experiments with 98 substances were evaluated. The results obtained revealed that dermal loading ranged mostly between 0.001 and 10 mg/cm2. In 87 experiments (63%), an inverse relationship was observed between relative dermal absorption and dermal loading. On average, relative absorption at high dermal loading was 33 times lower than at low dermal loading. Known skin irritating and volatile substances less frequently showed an inverse relationship between dermal loading and relative absorption. It was concluded that when using relative dermal absorption in regulatory risk assessment, its value should be determined at or extrapolated to dermal loadings relevant for the exposure conditions being evaluated.
n chapter 3 of this thesis, a literature search was presented with the aim to investigate whether neglecting the effects of repeated exposure may lead to an incorrect estimate of dermal absorption. The results demonstrated that the effect of repeated versus single exposure does not demonstrate a unique trend. Nevertheless, an increase in daily absorption was frequently observed upon repeated daily exposure. The little information available mostly concerned pharmaceuticals. However, consumers and workers may be repeatedly exposed to other types of chemicals, like disinfectants and cleaning products, which often contain biocidal active substances that may decrease the barrier function of the skin, especially after repeated exposure. These biocidal products, therefore, may present a safety risk that is not covered by the current risk assessment practice since absorption data are usually obtained by single exposure experiments. Consequently, it was decided to investigate the importance of this issue for biocide safety evaluation. As the literature search revealed that hardly any data on absorption upon repeated dermal exposure to biocides are available, it was concluded that data need to be generated by testing.
To cover the entire range of biocidal products in such testing, a representative series of biocidal substances should be tested, making in vitro testing of dermal absorption the preferred choice over in vivo testing. Based on an inventory made, it appeared that the 16 product types represented among the biocidal products authorised in the Netherlands could be clustered into 6 more or less homogeneous categories based on similarity in active substances. This result could facilitate experimental testing by providing a basis for selection of a limited number of representative compounds to be evaluated.
n chapter 4 of this thesis, the importance of the effect of repeated dermal exposure on skin permeability for biocide safety evaluation was investigated, using a selection of nine representative biocides from the inventory made in chapter 3. The in vitro dermal penetration of tritiated water and [14C]propoxur was chosen as a measure of the permeability and integrity of human abdominal skin after single and repeated exposure. The results indicated that single and repeated exposure to specific biocidal products (e.g. the quaternary ammonium chlorides DDAC and ADBAC) may significantly increase skin permeability, especially when the compounds are applied at high concentrations, while a substance like formaldehyde may reduce skin permeability under specific conditions.
n chapter 5 of this thesis, the in vitro dermal absorption kinetics of the quaternary ammonium compound didecyldimethylammonium chloride (DDAC) during single and repeated exposure was studied in more detail. In addition, the influence of biocidal formulations on the absorption of DDAC was investigated, because it was expected that formulation characteristics may be another factor influencing its dermal absorption. The analysis of biocidal products on the Dutch market, reported in chapter 3, indicated that DDAC is often used in combination with other active ingredients. DDAC was most frequently combined with formaldehyde, glutaraldehyde and/or alkyldimethylbenzylammonium chloride (ADBAC). Consequently, commercial formulations containing one or more of these additional active ingredients were selected, in addition to one formulation containing only DDAC as an active ingredient. The selected commercial formulations tended to reduce skin penetration of DDAC. This was most pronounced with the formulation containing the highest concentration of formaldehyde (196 mg/mL) and glutaraldehyde (106 mg/mL), which reduced the flux of DDAC across the skin by 95%. The reduction caused by the only tested formulation containing no other active ingredients than DDAC, and thus incorporating no aldehydes, was smallest, and did not reach statistical significance.
n chapter 6 of this thesis, a simple in silico model to predict finite dose dermal absorption from infinite dose data (kp and lag time) and the stratum corneum/water partition coefficient (KSC,W) was developed. This model was tentatively called Dermal Absorption Model for Extrapolation (DAME). As dermal exposure may occur under a large variety of conditions leading to quite different rates of absorption, such a predictive model using simple experimental or physicochemical inputs provides a cost-effective means to estimate dermal absorption under different conditions.
To evaluate the DAME, a series of in vitro dermal absorption experiments was performed under both infinite and finite dose conditions using a variety of different substances. The kp’s and lag times determined in the infinite dose experiments were entered into DAME to predict relative dermal absorption value under finite dose conditions. For six substances, the predicted relative dermal absorption under finite dose conditions was not statistically different from the measured value. For all other substances, measured absorption was overpredicted by DAME, but most of the overpredicted values were still lower than 100%, the European default absorption value for the tested compounds.
In conclusion, our finite dose prediction model (DAME) provides a useful and cost-effective estimate of in vitro dermal absorption, to be used in risk assessment for non-volatile substances dissolved in water at non-irritating concentrations.
n chapter 7 of this thesis, the results of the research reported in chapters 2 to 6 were put into perspective, the pitfalls and promises emanating from them discussed and general conclusions drawn. The possible influence of vehicles on absorption and the possible impact of irritative or corrosive vehicles or chemicals on the skin barrier have been demonstrated in this thesis. An in silico predictive model tentatively called DAME was developed, which enables the user to evaluate a variety of dermal exposure scenarios with limited experimental data (kp and lag time) and easy to obtain physicochemical properties (MW and log KOW). The predictions of our experiments reported in chapter 6 were compared to those of the Finite Dose Skin Permeation (FDSP) model published on the internet by the US Centers for Disease Control and Prevention (CDC). DAME outperformed FDSP (R2 of the correlation predicted/measured potential absorption 0.64 and 0.12, respectively). At present, the applicability domain of DAME is limited to non-volatile substances dissolved in aqueous solvents. However, in future the model will be adapted to include volatile substances as well.
Altogether, it is concluded that dermal exposure can be an important factor in risks posed by chemicals and should be taken into account in risk assessment. The methods to actually do this are still open for further improvement to better account for the various factors influencing skin penetration and to develop adequate combinations of in vitro and in silico models that can accurately predict human dermal absorption.
Water holding of protein gels
Urbonaite, V. - \ 2015
Wageningen University. Promotor(en): Erik van der Linden, co-promotor(en): Laurice Pouvreau; H.H.J. de Jongh. - Wageningen : Wageningen University - ISBN 9789462574229 - 206
sojaeiwit - ovalbumine - wei-eiwit - waterbergend vermogen - gelering - structuur - morfologie - reologie - permeabiliteit - centrifugeren - soya protein - ovalbumin - whey protein - water holding capacity - gelation - structure - morphology - rheology - permeability - centrifugation
Food products are typically multicomponent systems, where often the spatial volume is set by a protein continuous network. The ability of protein-based food products to entrap water and to prevent its exudation upon mechanical deformation is important for the texture and thus sensory perception of food products. Understanding of structural origins that determine gel water holding is therefore essential, and would allow designing foods with controlled sensory perception. Water removal from the gel (quantity, kinetics and mechanism) is related to the coarseness and deformation of the network. An understanding of the interplay between the effect of coarseness and stiffness on WH in fine and coarse gels allows one to take a better control and tune juiciness and the release of tastants from food products.
Live Faecalibacterium prausnitzii in an apical anaerobic model of the intestinal epithelial barrier
Ulluwishewa, D. ; Anderson, R.C. ; Young, W. ; McNabb, W.C. ; Baarlen, P. van; Moughan, P.J. ; Wells, J.M. ; Roy, N.C. - \ 2015
Cellular Microbiology 17 (2015)2. - ISSN 1462-5814 - p. 226 - 240.
necrosis-factor-alpha - crohns-disease - fusobacterium-prausnitzii - celiac-disease - hypoxia - permeability - expression - microbiota - diversity - inhibition
Faecalibacterium prausnitzii, an abundant member of the human commensal microbiota, has been proposed to have a protective role in the intestine. However, it is an obligate anaerobe, difficult to co-culture in viable form with oxygen-requiring intestinal cells. To overcome this limitation, a unique apical anaerobic model of the intestinal barrier, which enabled co-culture of live obligate anaerobes with the human intestinal cell line Caco-2, was developed. Caco-2 cells remained viable and maintained an intact barrier for at least 12¿h, consistent with gene expression data, which suggested Caco-2 cells had adapted to survive in an oxygen-reduced atmosphere. Live F.¿prausnitzii cells, but not ultraviolet (UV)-killed F.¿prausnitzii, increased the permeability of mannitol across the epithelial barrier. Gene expression analysis showed inflammatory mediators to be expressed at lower amounts in Caco-2 cells exposed to live F.¿prausnitzii than UV-killed F.¿prausnitzii, This, consistent with previous reports, implies that live F.¿prausnitzii produces an anti-inflammatory compound in the culture supernatant, demonstrating the value of a physiologically relevant co-culture system that allows obligate anaerobic bacteria to remain viable.
Serotonergic reinforcement of intestinal barrier function is impaired in irritable bowel syndrome
Keszthelyi, D. ; Troost, F.J. ; Jonkers, D.M. ; Eijk, H.M. van; Lindsey, P.J. ; Dekker, J. ; Buurman, W.A. ; Masclee, A.A.M. - \ 2014
Alimentary Pharmacology and Therapeutics 40 (2014)4. - ISSN 0269-2813 - p. 392 - 402.
reuptake transporter - visceral sensitivity - permeability - expression - tight - 5-hydroxytryptamine - predominant - 5-ht - sert - gut
Background Alterations in serotonergic (5-HT) metabolism and/or intestinal integrity have been associated with irritable bowel syndrome (IBS). Aims To assess the effects of the precursor of 5-HT, 5-hydroxytryptophan (5-HTP), on mucosal 5-HT availability and intestinal integrity, and to assess potential differences between healthy controls and IBS patients. Methods Fifteen IBS patients and 15 healthy volunteers participated in this randomised double-blind placebo-controlled study. Intestinal integrity was assessed by dual-sugar test and by determining the mucosal expression of tight junction proteins after ingestion of an oral bolus of 100 mg 5-HTP or placebo. Mucosal serotonergic metabolism was assessed in duodenal biopsy samples. Results 5-HTP administration significantly increased mucosal levels of 5-HIAA, the main metabolite of 5-HT, in both healthy controls (7.1 +/- 1.7 vs. 2.5 +/- 0.7 pmol/mg, 5-HTP vs. placebo, P = 0.02) and IBS patients (20.0 +/- 4.8 vs. 8.1 +/- 1.3 pmol/mg, 5-HTP vs. placebo, P = 0.02), with the latter group showing a significantly larger increase. Lactulose/L-rhamnose ratios were significantly lower after administration of 5-HTP (P <0.05) in healthy controls and were accompanied by redistribution of zonula occludens-1 (ZO-1), pointing to reinforcement of the barrier. In IBS, expression of the tight junction proteins was significantly lower compared to healthy controls, and 5-HTP resulted in a further decrease in occludin expression. Conclusions Oral 5-HTP induced alterations in mucosal 5-HT metabolism. In healthy controls, a reinforcement of the intestinal barrier was seen whereas such reaction was absent in IBS patients. This could indicate the presence of a serotonin-mediated mechanism aimed to reinforce intestinal barrier function, which seems to dysfunction in IBS patients.
Fractioning electrodialysis: a current induced ion exchange process
Galama, A.H. ; Daubaras, G. ; Burheim, O.S. ; Rijnaarts, H. ; Post, J.W. - \ 2014
Electrochimica Acta 136 (2014). - ISSN 0013-4686 - p. 257 - 265.
divalent ions - seawater desalination - membrane - monovalent - diffusion - transport - charge - nanofiltration - permeability - polarization
In desalination often multi ionic compositions are encountered. A preferential removal of multivalent ions over monovalent ions can be of interest to prevent scaling in the desalination process. Recently, a novel fractionating electrodialysis stack is described by Zhang et al., 2012 (in Sep. purify. Technol. 88). In the present work a small modification to such a stack was made, to create a current induced ion exchange process, in which no longer desalination occurs. This was done by building a membrane stack in which monovalent-selective ion-exchange membranes and standard grade ion-exchange membranes, with similar charge sign (so either anion or cation exchange groups), were placed alternatingly between an anode and a cathode to form a membrane stack. A proof of principle of the fractioning electrodialysis technology is given. Ternary mixtures, with a divalent-monovalent ion ratio similar to seawater, were used as feed water. For a cation and an anion fractioning stack, maximum fractionations of divalent ions were obtained of approximately 90 and 60%. At higher applied current density, ions can be fractionated to a larger extent than at lower applied current density. For both stacks the water recovery was 50%. Coulombic efficiency of both processes decrease rapidly after the start of the experiment. This leads to relatively large volumetric energy consumptions. (C) 2014 Elsevier Ltd. All rights reserved.
Validation of isovist variables as predictors of perceived landscape openness
Weitkamp, S.G. ; Lammeren, R.J.A. van; Bregt, A.K. - \ 2014
Landscape and Urban Planning 125 (2014). - ISSN 0169-2046 - p. 140 - 145.
preference - space - permeability - indicators - enclosure - distance - impacts
This paper tests the quality of calculated 2D isovist variables as predictors of perceived landscape openness. An isovist is the calculated field of view from a given viewpoint in space. Three isovist variables were selected to estimate openness: the minimum radial, the maximum radial and the average radial. An experiment with 32 participants was conducted to compare values of these calculated variables with perceived openness. The comparison showed that two variables, the maximum radial and average radial, explained most of the variation of perceived openness for groups and individuals. The three calculated isovist variables were strongly correlated to their measured equivalents in the field, which were obtained with a binocular with a rangefinder. The isovist variables also showed strong correlations with their perceived equivalents obtained by the perception of the 32 participants, except at very long distances. This research shows that the selected isovist variables are good indicators for perceived landscape openness.
Editorial: Dynamics of complex fluid-fluid interfaces
Sagis, L.M.C. ; Fischer, P. ; Anderson, P.D. - \ 2013
The European Physical Journal. Special Topics 222 (2013)1. - ISSN 1951-6355 - p. 1 - 5.
in-water emulsions - liquid interfaces - bending rigidity - rheology - fibrils - viscoelasticity - permeability - particles - mixtures - behavior
Human intestinal microbiota composition is associated with local and systemic inflammation in obesity
Verdam, F.J. ; Fuentes Enriquez de Salamanca, S. ; Jonge, C. de; Zoetendal, E.G. ; Erbil, R. ; Greve, J.W. ; Buurman, W.A. ; Vos, W.M. de; Rensen, S.S. - \ 2013
Obesity 21 (2013)12. - ISSN 1930-7381 - p. E607 - E615.
human gut microbiota - diet-induced obesity - high-fat diet - fecal calprotectin - nonalcoholic steatohepatitis - weight-loss - bowel - mice - permeability - disease
OBJECTIVE: Intestinal microbiota have been suggested to contribute to the development of obesity, but the mechanism remains elusive. The relationship between microbiota composition, intestinal permeability, and inflammation in nonobese and obese subjects was investigated. DESIGN AND METHODS: Fecal microbiota composition of 28 subjects (BMI 18.6-60.3 kg m-2 ) was analyzed by a phylogenetic profiling microarray. Fecal calprotectin and plasma C-reactive protein levels were determined to evaluate intestinal and systemic inflammation. Furthermore, HbA1c , and plasma levels of transaminases and lipids were analyzed. Gastroduodenal, small intestinal, and colonic permeability were assessed by a multisaccharide test. RESULTS: Based on microbiota composition, the study population segregated into two clusters with predominantly obese (15/19) or exclusively nonobese (9/9) subjects. Whereas intestinal permeability did not differ between clusters, the obese cluster showed reduced bacterial diversity, a decreased Bacteroidetes/Firmicutes ratio, and an increased abundance of potential proinflammatory Proteobacteria. Interestingly, fecal calprotectin was only detectable in subjects within the obese microbiota cluster (n = 8/19, P = 0.02). Plasma C-reactive protein was also increased in these subjects (P = 0.0005), and correlated with the Bacteroidetes/Firmicutes ratio (rs = -0.41, P = 0.03). CONCLUSIONS: Intestinal microbiota alterations in obese subjects are associated with local and systemic inflammation, suggesting that the obesity-related microbiota composition has a proinflammatory effect
Does acute tryptophan depletion affect peripheral serotonin metabolism in the intestine?
Keszthelyi, D. ; Troost, F.J. ; Jonkers, D.M. ; Donkelaar, E.L. van; Dekker, J. ; Buurman, W.A. ; Masclee, A.A. - \ 2012
American Journal of Clinical Nutrition 95 (2012)3. - ISSN 0002-9165 - p. 603 - 608.
5-hydroxyindoleacetic acid - gastrointestinal-tract - cerebrospinal-fluid - brain - permeability - depression - cortisol - reuptake - humans - lumbar
Background: Serotonin (5-hydroxytryptamine; 5-HT), a tryptophan metabolite, plays an important regulatory role in the human central nervous system and in the gastrointestinal tract. Acute tryptophan depletion (ATD) is currently the most widely established method to investigate 5-HT metabolism. Objective: The aim of this study was to assess the effect of an acute decrease in the systemic availability of tryptophan on intestinal 5-HT metabolism and permeability. Design: Thirty-three healthy volunteers (17 with ATD, 3 of whom dropped out; 16 placebo) participated in this randomized placebo-controlled study. Plasma and duodenal mucosal concentrations of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and kynurenic acid (KA) were measured by HPLC-mass spectrometry. Intestinal barrier function was assessed with a multisugar plasma test, and analysis of tight junction transcription was performed in duodenal biopsy samples obtained by gastroduodenoscopy. Results: Mucosal 5-HT, 5-HIAA, and KA concentrations remained unaltered by ATD. In contrast, ATD significantly decreased plasma 5-HT (P <0.05) and 5-HIAA (P <0.0001) concentrations. After endoscopy, a significant increase in plasma 5-HT concentrations was observed in the placebo group (P = 0.029) compared with the ATD group. Moreover, a significant increase in plasma KA concentrations over time was found in the placebo group (P <0.05). No changes in intestinal barrier function were observed. Conclusions: An acute decrease in precursor availability does not affect mucosal concentrations of serotonergic metabolites, in contrast with systemic concentrations. ATD alters biochemical responses to acute stress from the endoscopic examination reflected by lower 5-HT concentrations. Changes in 5-HT concentrations were paralleled by alterations in KA concentrations, which suggest competition between the 2 metabolic pathways for the mutual precursor. This trial was registered at clinicaltrials.gov as NCT00731003. Am J Clin Nutr 2012;95:603-8.
How to deal with visco-elastic properties of cellular tissues during osmotic dehydration
Oliver, L. ; Betoret, N. ; Fito, P. ; Meinders, M.B.J. - \ 2012
Journal of Food Engineering 110 (2012)2. - ISSN 0260-8774 - p. 278 - 288.
var. granny-smith - mass-transfer - apple slices - compositional profiles - vacuum impregnation - structural-changes - water relations - food - kinetics - permeability
In this work, vacuum impregnated apple discs with different isotonic solutions (sucrose and trehalose) were equilibrated during osmotic dehydration (55°Brix glucose at 40 °C). Changes in sample composition (water and soluble solid contents), weight and volume are analysed. A mathematical model is proposed to describe and quantify the outflow of water from the protoplast as well as the visco-elastic behaviour of the cell. Good correspondence between simulated and measured data of non impregnated samples and samples impregnated with isotonic solutions of sucrose or trehalose during long term osmotic dehydration is obtained. Fitted values of the cell permeability correspond well with tabulated values. Furthermore, also the obtained values of the parameters describing the mechanical properties of the cell wall and Hectian strands seem to reflect the observed structural development of these structures for the different treated samples well.
Does crumb morphology affect water migration and crispness retention in crispy breads?
Hirte, A. ; Primo-Martin, C. ; Meinders, M.B.J. ; Hamer, R.J. - \ 2012
Journal of Cereal Science 56 (2012)2. - ISSN 0733-5210 - p. 289 - 295.
crust formation - image-analysis - baking - permeability - sorption - scale - model - grain
Crispness of bread is rapidly lost because of water migration inside the crumb towards the crust. How crumb properties determine this process independent of crust properties has not been examined before. Therefore, the aim of this study was to analyze and explain the influence of crumb morphology on the overall crispness retention. Crispness retention was determined by analyzing the acoustic emission of breads differing in either crust or crumb morphology. When crumb morphology is coarse with a lower number of large connections between the air cells, the effective diffusion coefficient is reduced. This effective diffusion coefficient of crumb, which equals approximately half the value of air, was estimated using X-ray micro-computer tomography images of crumb pieces. If the crumb has a lower effective diffusion coefficient, bread with similar crust properties has significantly longer crispness retention. Despite this, our data show that variations in properties of crust, which has 30 times higher permeability than crumb, have a larger impact on crispness retention than variations in properties of crumb.
Effect of preventive supplementation with zinc and other micronutrients on non-malarial morbidity in Tanzanian pre-school children: a randomized trial
Veenemans, J. ; Schouten, L.R.A. ; Ottenhof, M. ; Mank, T. ; Uges, D.R.A. ; Mbugi, E.V. ; Demir, A.Y. ; Kraaijenhagen, R.J. ; Savelkoul, H.F.J. ; Verhoef, J.C.M. - \ 2012
PLoS ONE 7 (2012)8. - ISSN 1932-6203
iron supplementation - prepubertal children - caco-2 - growth - interventions - permeability - vitamins - alters - copper - cells
Background The efficacy of preventive zinc supplementation against diarrhea and respiratory illness may depend on simultaneous supplementation with other micronutrients. We aimed to assess the effect of supplementation with zinc and multiple micronutrients on diarrhea and other causes of non-malarial morbidity. Methods and Findings Rural Tanzanian children (n = 612) aged 6–60 months and with height-for-age z-score <–1.5 SD were randomized to daily supplementation with zinc (10 mg) alone, multi-nutrients without zinc, multi-nutrients with zinc, or placebo. Children were followed for an average of 45 weeks. During follow-up, we recorded morbidity episodes. We found no evidence that concurrent supplementation with multi-nutrients influenced the magnitude of the effect of zinc on rates of diarrhea, respiratory illness, fever without localizing signs, or other illness (guardian-reported illness with symptoms involving skin, ears, eyes and abscesses, but excluding trauma or burns). Zinc supplementation reduced the hazard rate of diarrhea by 24% (4%–40%). By contrast, multi-nutrients seemed to increase this rate (HR; 95% CI: 1.19; 0.94–1.50), particularly in children with asymptomatic Giardia infection at baseline (2.03; 1.24–3.32). Zinc also protected against episodes of fever without localizing signs (0.75; 0.57–0.96), but we found no evidence that it reduced the overall number of clinic visits. Conclusions We found no evidence that the efficacy of zinc supplements in reducing diarrhea rates is enhanced by concurrent supplementation with other micronutrients. By reducing rates of fever without localizing signs, supplementation with zinc may reduce inappropriate drug use with anti-malarial medications and antibiotics.
Naar een database van bodemhydraulische karakteristieken voor Nederland
Verzandvoort, S.J.E. ; Vroon, H.R.J. ; Wesseling, J.G. ; Bakker, G. ; Oostindie, K. ; Stoffelsen, G.H. ; Heidema, A.H. ; Heuvelink, G.B.M. - \ 2012
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2238) - 148
bodemfysica - bodemwater - permeabiliteit - fysische bodemeigenschappen - databanken - soil physics - soil water - permeability - soil physical properties - databases
Bodemhydraulische karakteristieken zijn relaties van vochtgehalte (θ) en doorlatendheid (K) met de capillaire drukhoogte (h) in de onverzadigde zone van de bodem. Deze karakteristieken worden gebruikt voor modelsimulaties van het transport van water en opgeloste stoffen in de onverzadigde zone van de bodem. Doel van deze studie is de bij Alterra beschikbare basisgegevens voor bodemhydraulische karakteristieken te controleren, aan te vullen en beschikbaar te stellen voor het Bodemkundig Informatie Systeem (BIS) van Alterra. Hiervoor werden meetgegevens, afgeleide gegevens en beschrijvende gegevens van grondmonsters in de bestaande database Priapus gecorrigeerd en aangevuld. De variatie door metingen, functiebeschrijvingen en ruimtelijke variatie werd inzichtelijk gemaakt. Voor een betere bepaling van afgeleide gegevens uit de meetgegevens werd een nieuwe functiebeschrijving voor bodemhydraulische karakteristieken ontwikkeld in de vorm van cubical splines. Om de selectie van bodemhydraulische karakteristieken meer flexibel te maken voor gebruikers werd een nieuwe indeling van Nederlandse gronden ontwikkeld met als criteria: afzettingsmilieu, textuur en organische stofgehalte.
Green-Kubo relations for dynamic interfacial excess properties
Sagis, L.M.C. - \ 2012
Physica A 391 (2012)15. - ISSN 0378-4371 - p. 3805 - 3815.
in-water emulsions - extended irreversible thermodynamics - fourier-transform rheology - permeability
In this paper we analyze the fluctuations of the in-plane interfacial excess fluxes in multiphase systems, in the context of the extended irreversible thermodynamics formalism. We derive expressions for the time correlation functions of the surface extra stress tensor, the surface mass flux vector, and the surface energy flux vector, and use these expressions to derive Green–Kubo relations for the surface shear viscosity, the surface dilatational viscosity, the surface diffusion coefficient, and the surface thermal conductivity. These Green-Kubo relations can be used to compute these excess transport coefficients using for example molecular dynamics simulations
Alternative Analytical Expressions for the General van Genuchten-Mualem and van Genuchten-Burdine Hydraulic Conductivity Models
Neto, D.D. ; Lier, Q.D. van; Genuchten, M.T. van; Reichardt, K. ; Metselaar, K. ; Nielsen, D.R. - \ 2011
Vadose Zone Journal 10 (2011)2. - ISSN 1539-1663 - p. 618 - 623.
unsaturated soils - porous-media - permeability - flow
The van Genuchten expressions for the unsaturated soil hydraulic properties, first published in 1980, are used frequently in various vadose zone flow and transport applications assuming a specific relationship between the m and n soil hydraulic parameters. By comparison, probably because of the complexity of the hydraulic conductivity equations, the more general solutions with independent m and n values are rarely used. We expressed the general van Genuchten-Mualem and van Genuchten-Burdine hydraulic conductivity equations in terms of hypergeometric functions, which can be approximated by infinite series that converge rapidly for relatively large values of the van Genuchten-Mualem parameter n but only very slowly when n is close to one. Alternative equations were derived that provide very close approximations of the analytical results. The newly proposed equations allow the use of independent values of the parameters m and n in the soil water retention model of van Genuchten for subsequent prediction of the van Genuchten-Mualem and van Genuchten-Burdine hydraulic conductivity models, thus providing more flexibility in fitting experimental pressure-head-dependent water content, theta(h), and hydraulic conductivity, K(h), or K(theta) data.
Supplemental Antioxidants Do Not Ameliorate Colitis Development in HLA-B27 Transgenic Rats Despite Extremely Low Glutathione Levels in Colonic Mucosa
Schepens, M.A.A. ; Vink, C. ; Schonewille, A.J. ; Roelofs, H.M.J. ; Brummer, R.J. ; Meer, R. van der; Bovee-Oudenhoven, I.M.J. - \ 2011
Inflammatory Bowel Diseases 17 (2011)10. - ISSN 1078-0998 - p. 2065 - 2075.
inflammatory-bowel-disease - dietary calcium - ulcerative-colitis - salmonella - cancer - cells - permeability - prevention - nutrition - radicals
Background: Oxidative stress is presumed to play an important role in inflammatory bowel disease (IBD). Accordingly, antioxidant supplementation might be protective. Dietary calcium inhibited colitis development in HLA-B27 transgenic rats, an animal model mimicking IBD. As antioxidants might act at mucosa level and calcium predominantly in the gut lumen, we hypothesize that the combination has additive protective effects on colitis development. Methods: HLA-B27 rats were fed a control diet or the same diet supplemented with the antioxidants glutathione, vitamin C, and vitamin E, or supplemented with both antioxidants and calcium. Oxidative stress in colonic mucosa, colonic inflammation, intestinal permeability, and diarrhea were quantified. Results: Intestinal permeability, diarrhea, myeloperoxidase, and interleukin-1 beta levels were significantly lower in rats fed both antioxidants and calcium compared to rats supplemented with antioxidants only. No beneficial effects were observed in rats fed the diet supplemented with antioxidants only. Strikingly, despite extremely low colonic mucosal glutathione levels in HLA-B27 rats, there was no oxidative stress-related damage. Subsequent analyses showed no defect in expression of glutathione synthesis genes. Additional experiments, comparing young and older HLA-B27 rats, showed that glutathione levels and also reactive oxygen species production decreased with progression of intestinal inflammation. Conclusions: Antioxidant supplementation was ineffective in HLA-B27 rats despite low mucosal glutathione levels, because colitis development did not coincide with oxidative stress in this model. This indicates that the neutrophilic respiratory burst, and thus innate immune defense, is compromised in HLA-B27 rats. As supplementation with both calcium and antioxidants attenuated colitis development, we speculate that this protective effect is attributed to calcium only.
ANGPTL4 modulates vascular junction integrity by integrin signaling and disruption of intercellular VE-cadherin and claudin-5 clusters
Huang, R.L. ; Teo, Z.Q. ; Chong, H.C. ; Zhu, P.C. ; Tan, M.J. ; Tan, C.K. ; Lam, C.R.I. ; Sng, M.K. ; Leong, D.T.W. ; Tan, S.M. ; Kersten, A.H. ; Ding, J.L. ; Li, H.Y. ; Tan, N.S. - \ 2011
Blood : journal of the American Society of Hematology 118 (2011)14. - ISSN 0006-4971 - p. 3990 - 4002.
endothelial-cell - adherens junctions - tight junctions - 4 interacts - metastasis - cancer - permeability - catenin - lung - angiopoietin-like-4
Vascular disruption induced by interactions between tumor-secreted permeability factors and adhesive proteins on endothelial cells facilitates metastasis. The role of tumor-secreted C-terminal fibrinogen-like domain of angiopoietin-like 4 (cANGPTL4) in vascular leakiness and metastasis is controversial because of the lack of understanding of how cANGPTL4 modulates vascular integrity. Here, we show that cANGPTL4 instigated the disruption of endothelial continuity by directly inter-acting with 3 novel binding partners, integrin alpha 5 beta 1, VE-cadherin, and claudin-5, in a temporally sequential manner, thus facilitating metastasis. We showed that cANGPTL4 binds and activates integrin alpha 5 beta 1-mediated Rac1/PAK signaling to weaken cell-cell contacts. cANGPTL4 subsequently associated with and declustered VE-cadherin and claudin-5, leading to endothelial disruption. Interfering with the formation of these cANGPTL4 complexes delayed vascular disruption. In vivo vascular permeability and metastatic assays performed using ANGPTL4-knockout and wild-type mice injected with either control or ANGPTL4-knockdown tumors confirmed that cANGPTL4 induced vascular leakiness and facilitated lung metastasis in mice. Thus, our findings elucidate how cANGPTL4 induces endothelial disruption. Our findings have direct implications for targeting cANGPTL4 to treat cancer and other vascular pathologies. (Blood. 2011;118(14):3990-4002)
Responses of gut microbiota and glucose and lipid metabolism to prebiotics in genetic obese and diet-induced leptin-resistant mice
Everard, A. ; Derrien, M.M.N. ; Possemiers, S. ; Vos, W.M. de; Delzenne, N.M. ; Schrenzel, J. ; Cani, P.D. - \ 2011
Diabetes 60 (2011)11. - ISSN 0012-1797 - p. 2775 - 2786.
glucagon-like peptide-1 - inulin-type fructans - phylogenetic microarray - insulin-resistance - inflammation - permeability - endotoxemia - mechanism - rats - adipogenesis
OBJECTIVE To investigate deep and comprehensive analysis of gut microbial communities and biological parameters after prebiotic administration in obese and diabetic mice. RESEARCH DESIGN AND METHODS Genetic (ob/ob) or diet-induced obese and diabetic mice were chronically fed with prebiotic-enriched diet or with a control diet. Extensive gut microbiota analyses, including quantitative PCR, pyrosequencing of the 16S rRNA, and phylogenetic microarrays, were performed in ob/ob mice. The impact of gut microbiota modulation on leptin sensitivity was investigated in diet-induced leptin-resistant mice. Metabolic parameters, gene expression, glucose homeostasis, and enteroendocrine-related L-cell function were documented in both models. RESULTS In ob/ob mice, prebiotic feeding decreased Firmicutes and increased Bacteroidetes phyla, but also changed 102 distinct taxa, 16 of which displayed a >10-fold change in abundance. In addition, prebiotics improved glucose tolerance, increased L-cell number and associated parameters (intestinal proglucagon mRNA expression and plasma glucagon-like peptide-1 levels), and reduced fat-mass development, oxidative stress, and low-grade inflammation. In high fat-fed mice, prebiotic treatment improved leptin sensitivity as well as metabolic parameters. CONCLUSIONS We conclude that specific gut microbiota modulation improves glucose homeostasis, leptin sensitivity, and target enteroendocrine cell activity in obese and diabetic mice. By profiling the gut microbiota, we identified a catalog of putative bacterial targets that may affect host metabolism in obesity and diabetes