Depth distribution and mobility of a harpacticoid copepod within the bed sediment of an alpine brook

The harpacticoid copepod Limnocamptus echinatus (Mrazek) shows a very distinct large-scale vertical distribution within the bed sediments of Oberer Seebach, a second-order gravel stream. The population peak appears in a sediment layer between 15 and 35 cm over long periods on average. Abundances are significantly lower in the topmost sediments and sediment layers below 50 cm depth. The large-scale vertical distribution is mainly influenced by the changes and pattern of temperature and discharge, which influences the current velocity of the surface and interstitial water. Effects appear quite different, when permanent flooded areas and areas that periodically fall dry on the surface are compared. Limnocamptus echinatus is forced deeper into the sediments of the gravel bar during low water temperatures and/or high discharge situations. On permanent flooded areas the vertical distribution is more stable over long periods, but higher fluctuations occur during short periods. The Limnocamptus echinatus population shows higher mobility in deeper sediment layers (40 to 60 cm sediment depth). Comparing longer periods, water flow and the transport of fine material differ in deeper sediment layers. The water current is much slower, producing a tendency for fine material sedimentation. This might be the main reason for the higher mobility in deeper sediment layers and the restriction of 90 per cent of the Limnocamptus echinatus population to a sediment depth of 50 cm. High mobility in vertical and horizontal directions within the bed sediments is interpreted as normal reactions and adaptations to the dynamic behaviour of the system, mainly forced by physical parameters. Biological parameters appear as subdominant for large-scale vertical distributions.     

Negative Priming Effects in Children Engaged in Nonspatial Tasks: Evidence for Early Development of an Intact Inhibitory Mechanism.

Three experiments are reported that examined conceptual negative priming effects in children 5 to 12 years of age. Experiment 1 used a negative priming variant of a flanker task requiring the naming of a central color blob flanked by irrelevant distractors. Experiment 2 used a negative priming variant of the Stroop color-word task. Experiment 3 used a same-different matching task with novel 3-D shapes. Results revealed significant and equivalent magnitudes of negative priming across the tested age groups for all 3 tasks. It is concluded that the inhibitory mechanism underlying conceptual (i.e., identity or semantic) negative priming in visual selective attention tasks is intact in young children. Because the findings and conclusions diverge from the developmental literature on negative priming, the authors attempt to reconcile the contradictions by pinning down the reasons for the discrepancies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pharmaceutical Development of Nanostructured Vesicular Hydrogel Formulations of Rifampicin for Wound Healing

Chronic wounds exhibit elevated levels of inflammatory cytokines, resulting in the release of proteolytic enzymes which delay wound-healing processes. In recent years, rifampicin has gained significant attention in the treatment of chronic wounds due to an interesting combination of antibacterial and anti-inflammatory effects. Unfortunately, rifampicin is sensitive to hydrolysis and oxidation. As a result, no topical drug product for wound-healing applications has been approved. To address this medical need two nanostructured hydrogel formulations of rifampicin were developed. The liposomal vesicles were embedded into hydroxypropyl methylcellulose (HPMC) gel or a combination of hyaluronic acid and marine collagen. To protect rifampicin from degradation in aqueous environments, a freeze-drying method was developed. Before freeze-drying, two well-defined hydrogel preparations were obtained. After freeze-drying, the visual appearance, chemical stability, residual moisture content, and redispersion time of both preparations were within acceptable limits. However, the morphological characterization revealed an increase in the vesicle size for collagen–hyaluronic acid hydrogel. This was confirmed by subsequent release studies. Interactions of marine collagen with phosphatidylcholine were held responsible for this effect. The HPMC hydrogel formulation remained stable over 6 months of storage. Moving forward, this product fulfills all criteria to be evaluated in preclinical and clinical studies.     

Hydroperoxid-Abbau durch Isomerase aus Hafer. Untersuchungen zum Reaktionsmechanismus

Zusammenfassung Isomerase aus Hafer wird durch Hydroxyoctadecadiensduren [Monohydroxysäuren] in ähnlich starkem Maße gehemmt wie durch Linolsäurehydroperoxide [LHPO]. Hydroxysduren scheinen sich wie LHPO an das Enzym anzulagern. Durch Zusatz von (1-¹⁴C)-Hydroxysäuren bei einem LHPO-Abbau-Versuch wurde untersucht, ob die isomeratische Bildung der Epoxyhydroxysduren über einen inter-oder intramolekularen Mechanismus verläuft. Bei dem Versuch traten radioaktiv-markierte Trihydroxysduren auf—die aus den primdr gebildeten Epoxyhydroxyoctadecensduren durch Hydrolyse entstehenden Reaktionsprodukte des isomeratischen LHPO-Abbaus. Die Auswertung ergab, daß mindestens 70% der LHPO intermolekular reagiert haben.

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Hydroperoxide degradation by oat isomerase. Investigation of the reaction mechanism

Summary Oat isomerase is inhibited by hydroxyoctadecadienoic acids (monohydroxy acids) to a degree comparable with inhibition by linoleic acid hydroperoxides (LHPO). Hydroxy acids seem to combine with the enzyme like LHPO do. In an experiment on LHPO breakdown by isomerase 1-¹⁴C-hydroxy acids were added and it was examined whether the epoxyhydroxy acids are formed by an intermolecular or intramolecular mechanism. In this experiment 1-¹⁴C-labeled trihydroxy acids were formed; they arise from the hydrolysis of epoxyhydroxyoctadecenoic acids formed on their part by isomerase effected LHPO-breakdown. It was determined that at least 70% of LHPO are converted by intermolecular reaction.

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Herrn Stadtehemiedirektor i. R. Dr. Curt Wilhelm zum 76. Geburtstag.     

Emulsifier Composition of Solid Lipid Nanoparticles (SLN) Affects Mechanical and Barrier Properties of SLN‐Protein Composite Films

Protein films can be applied to improve food quality and to reduce packaging waste. To overcome their poor water barrier properties, lipids are often incorporated. The function of incorporated lipid depends on the interface between filler and matrix. This study aimed to tailor the properties of a protein–lipid film by designing the oil/water interface to see if the concept of inactive/active filler is valid. Therefore, we varied the emulsifier stabilizing solid lipid nanoparticles (SLN) to promote (via β‐lactoglobulin) or to minimize (via Tween 20) interactions between particle surface and protein. SLN were incorporated into protein films and film properties were determined. Addition of SLN led to significantly decreased water vapor permeability (WVP) of protein films. However, WVP was mainly affected by the emulsifiers and not by the lipid. Protein‐stabilized SLN (BS) replaced a lacking protein in the protein network and therefore did not influence the mechanical properties of the films at ambient temperature. BS‐composite films were temperature sensitive, as lipid and sucrose palmitate melted at temperatures above 40 °C. Tween 20‐stabilized SLN (TS) led to reduced tensile strengths, probably due to perturbative effects of TS and plasticizing effects of Tween 20. Dynamic mechanical analysis showed that TS and Tween 20 increased film mobility. Melting of lipid and emulsifiers, and temperature‐dependent behavior of Tween 20 led to a strong temperature dependence of the film stiffness. By designing the interface, particles can be used to tailor mechanical properties of protein films. Tuned edible films could be used to control mass transfers between foods.