Natuurpotentie twee percelen in Needse Achterveld

Voor twee graslandpercelen in het Needse Achterveld is behoefte aan bodemkundige informatie over de potenties van deze percelen. Ze worden begraasd door Schotse Hooglander

Ecohydrologie en bodemchemie Veluwemeerkust

Voor het gebied Veluwemeerkust tussen Harderwijk, Nunspeet, Hierden en het Veluwemeer werden in opdracht van Natuurmonumenten gelijktijdig twee onderzoeken uitgevoerd. In een ecohydrologisch onderzoek is onderzocht in hoeverre kwelinvloed in maaiveld voorkomt en hoe dit door inrichtingsmaatregelen is te verbeteren. Uit interpretatie van bodemkundige en hydrologische kenmerken in twee transecten en een aantal locaties verspreid door het gebied kon afgeleid worden dat vrijwel overal in het gebied zacht grondwater voorkomt, maar dat dit als gevolg van de diepe ontwatering niet overal het maaiveld kan bereiken. Door hydrologische maatregelen is dat te verbeteren. In het bodemchemisch onderzoek werd de fosfaattoestand in het gebied beschreven in relatie tot de gewenste natuurdoeltypen Blauwgrasland en Dotterbloemhooiland

Drug interactions may be important risk factors for methotrexate neurotoxicity, particularly in pediatric leukemia patients

Purpose: Methotrexate administration is associated with frequent adverse neurological events during treatment for childhood acute lymphoblastic leukemia. Here, we present evidence to support the role of common drug interactions and low vitamin B12 levels in potentiating methotrexate neurotoxicity. Methods: We review the published evidence and highlight key potential drug interactions as well as present clinical evidence of severe methotrexate neurotoxicity in conjunction with nitrous oxide anesthesia and measurements of vitamin B12 levels among pediatric leukemia patients during therapy. Results: We describe a very plausible mechanism for methotrexate neurotoxicity in pediatric leukemia patients involving reduction in methionine and consequential disruption of myelin production. We provide evidence that a number of commonly prescribed drugs in pediatric leukemia management interact with the same folate biosynthetic pathways and/or reduce functional vitamin B12 levels and hence are likely to increase the toxicity of methotrexate in these patients. We also present a brief case study supporting out hypothesis that nitrous oxide contributes to methotrexate neurotoxicity and a nutritional study, showing that patients. Conclusions: Use of nitrous oxide in pediatric leukemia patients at the same time as methotrexate use should be avoided especially as many suitable alternative anesthetic agents exist. Clinicians should consider monitoring levels of vitamin B12 in patients suspected of having methotrexate- induced neurotoxic effects

Platelet-activating factor: an inflammatory mediator in the acute phase of allergic conjunctivitis in a guinea-pig model

The role of platelet-activating factor (PAF) as a mediator of increased conjunctival vascular permeability was investigated in a guinea-pig model of immediate hypersensitivity. Vascular permeability of the conjunctiva was determined by measuring the albumin content in lavage fluid (LF) after topical challenge with either PAF or ovalbumin. PAF produced a dose-dependent increase of the vascular permeability within minutes. Topical pretreatment with levocabastine, a potent histamine H1-antagonist demonstrated no effect towards the vascular permeability in response to PAF provocation. Pretreatment with eyedrops containing the specific PAF antagonist BN 52021 (1%) showed a significant inhibition of the vascular permeability (60.2%) and the clinical score (27.5%) after PAF challenge. In sensitized guinea-pigs, levocabastine showed a marked inhibition of both the vascular permeability (80.5%) and the clinical score (70%) after topical challenge with ovalbumin. BN 2021, although to a lesser extent, showed a similar effect towards the vascular permeability (26.8%) and the clinical score (28%) after antigen provocation. When BN 52021 and levocabastine were administered in combination, the vascular permeability was significantly decreased after antigen challenge in comparison with eyes pretreated with levocabastine alone. These results indicate that PAF plays a role in the acute phase of allergic conjunctivitis in the guinea-pig

Reply: Methotrexate neurotoxicity due to drug interactions: an inadequate folinic acid effect

No abstract available

Bodemgesteldheid en potenties voor natuurontwikkeling van 4 deelgebieden in het herinrichtingsgebied Beekdal Linde, 4de module Wolvega-Zuid

De Dienst Landelijk Gebied te Leeuwarden heeft Alterra gevraagd om de bodemgesteldheid van een aantal gebieden nauwkeurig in kaart te brengen. Voor één deelgebied is een fosfaatbemonstering gedaan en in alle deelgebieden is, bij ongeveer de helft van de beschreven boringen met pH-indicatorstripjes, de zuurgraad van de bodem op verschillende dieptes bepaald. In 2010 heeft Alterra in zeven, oostelijker gelegen deelgebieden, vergelijkbaar onderzoek verricht. De te onderzoeken deelgebieden liggen in, en op de overgang van, het beekdal van de Linde. Het gaat in totaal om 4 deelgebieden met een totale oppervlakte van ca. 76 h

Natuurpotentie Willinks Weust

Dienst Landelijk Gebied (DLG) heeft van de provincie Gelderland in het kader van NBL (natuur buiten landinrichting) opdracht gekregen voor de inrichting van een aantal percelen nabij de steengroeve ten oosten van Winterwijk. Het gebied is bekend onder de naam Willinks Weust. Alvorens kan worden ingericht is een ecohydrologisch en biochemisch onderzoek noodzakelijk. Het gebied is echter ook sterk verdroogd door diepe ontwateringsloten, met name in het erosiedal en op de overgang naar het plateau. Ook de steengroeve aan de noordkant van het gebied heeft in een overgangzone een verdrogende invloed. Inrichting van de percelen en herstel van de hydrologie bieden goede mogelijkheden de natuurwaarden in het gebied te herstellen en versterken

Permeability of blood-tear barrier to fluorescein and albumin after application of platelet-activating factor to the eye of the guinea pig

One of the inflammatory responses of the eye to local application of platelet-activating factor (PAF) is oedema of the conjunctiva, caused by extravasation of plasma. Aim of the study was to investigate if fluorescein would leak from the blood into the tears together with plasma protein after application of PAF to the eye. Fluorescein was given intraperitoneally 30 min prior to application of 25 μl of 0.1% solution of PAF. Thirty min after PAF the tear film was collected by washing the surface of the eye with 25 μl of phosphate buffered saline (PBS). Fluorescein in eye washings and in plasma was measured by fluorophotometry and albumin by immunodiffusion. Both fluorescein and albumin appeared in a related fashion in tears, being absent in washings of placebo-treated control eyes. Extravasation of fluorescein can be used as a measure for plasma leakage in the conjunctiva with the advantage over the Evans Blue method that the former is a non-invasive method

High temperature dewatering of ethanol by vapour permeation and pervaporation with HybSi® membranes

Ethanol is one of the most important commodity chemicals used in a broad range of applications and can be produced by the hydrolysis of ethylene, though by far the largest fraction of ethanol is produced via fermentation mainly using 1st generation feedstock. Regardless of the source of the ethanol, from fermentation or from direct hydration of ethylene, the product is normally a dilute aqueous solution. The product is fed to a distillation system to concentrate ethanol. The separation of ethanol and water is complicated because ethanol and water form an azeotrope at 95.6 weight% ethanol. It is not possible to produce pure ethanol from an azeotropic mixture by normal distillation. Pervaporation is a method for dehydration of organics such as ethanol, which substantially avoids drawbacks of azeotropic distillation and adsorption. As the pervaporation process is not governed by thermodynamic equilibria and the selectivity is determined by the difference in permeation rates of components through the membrane, mixtures of components with close boiling points and azeotropic mixtures can be effectively separated. Pervaporation exhibits its highest efficiency in a concentration range of the ethanol-water mixture where distillation is least effective, namely, at high ethanol concentrations of 90-95 wt.%, especially in the vicinity of the azeotropic concentration. Previous studies have shown that hybrid distillation processes combined with either pervaporation or vapour permeation can be very attractive for the separation of liquid mixtures. Such a hybrid process leads to large energy savings when the membrane is used for breaking the azeotrope. At the preferred process conditions currently available commercial polymer and zeolite membranes cannot be used. In this study, the focus is on membrane stability at higher operating temperatures in a water ethanol mixture for sol–gel derived Hybsi® membranes and the membrane performance in pervaporation and vapour permeation. The stability of the membranes is one of the crucial factors of their application in industrial separation processes. A comparison between pervaporation and vapour permeation has been made in which water removal from ethanol has been used as an example. By applying higher temperatures and thus higher driving forces in the membrane unit the required membrane area and the total costs of the process are strongly reduced. The comparison was based on endurance tests, in the dehydration of ethanol at 150°C. The high hydrothermal and chemical stability of the membrane was proven in continuous measurements (24/7) that lasted for periods of over 500 days. The membrane performance was followed during this period of time by measuring the flux and membrane selectivity. Both in pervaporation and vapour permeation a good and stable membrane performance was obtained after a stabilisation period and from a flux and selectivity point of view at 150°C both membrane operation options show similar results. Detailed test results will be presented. For ethanol dehydration vapour permeation would be preferred above pervaporation as advantage can be taken of the vapour already present at the top of the distillation column which will still be used to remove major part of the water present. The presented results show that HybSi® membranes are applicable in the dehydration of ethanol by pervaporation and vapour permeation at higher temperatures. The high temperature use leads to a broadened application window and will open up markets that have so far been inaccessible for commercially available pervaporation and vapour permeation membranes