Rheoreaction impacts dispersal of fish larvae in restored rivers.

Connectivity of nurseries and spawning habitats for young of the year life stage is essential for successful recruitment of fish populations and therefore provides a key indicator for river restoration measures. Models for dispersal offer the potential to draw conclusions regarding restoration scenarios and to fill knowledge gaps about possible implications for fish populations. A newly developed rheoreaction-based correlated random walk model (RCRW), in combination with a three-dimensional numerical model and a non-steady-state particle tracing model, was applied for nase carp larvae () before and after a restoration project on the river Danube, Austria.

Aquatic methane dynamics in a human-impacted river-floodplain of the Danube.

River-floodplain systems are characterized by changing hydrological connectivity and variability of resources delivered to floodplain water bodies. Although the importance of hydrological events has been recognized, the effect of flooding on CH concentrations and emissions from European, human-impacted river-floodplains is largely unknown. This study evaluates aquatic concentrations and emissions of CH from a highly modified, yet partly restored river-floodplain system of the Danube near Vienna (Austria).

The Danube so colourful: a potpourri of plastic litter outnumbers fish larvae in Europe's second largest river.

Previous studies on plastic pollution of aquatic ecosystems focused on the world's oceans. Large rivers as major pathways for land-based plastic litter, has received less attention so far. Here we report on plastic quantities in the Austrian Danube.

Large-scale controls on potential respiration and denitrification in riverine floodplains.

Restoration measures of deteriorated river ecosystems generally aim at increasing the spatial heterogeneity and connectivity of these systems in order to increase biodiversity and ecosystem stability. While this is believed to benefit overall ecological integrity, consequences of such restoration projects on biogeochemical processes per se (i.e.

Modelling highly variable environmental factors to assess potential microbial respiration in complex floodplain landscapes.

The hydrological exchange conditions strongly determine the biogeochemical dynamics in river systems. More specifically, the connectivity of surface waters between main channels and floodplains is directly controlling the delivery of organic matter and nutrients into the floodplains, where biogeochemical processes recycle them with high rates of activity. Hence, an in-depth understanding of the connectivity patterns between main channel and floodplains is important for the modelling of potential gas emissions in floodplain landscapes.

Photoinjection of hydrogen and the nature of a giant shift of the fundamental absorption edge in highly disordered V2O5 films.

Production of atomic photochemical hydrogen under the action of light and its subsequent injection into transition metal oxides has yielded numerous interesting results. Here we report on the mechanism of the photo-induced hydrogen transfer between adsorbed organic molecules and the surface of highly disordered V(2)O(5) films. We have managed to carry out the photoinjection of hydrogen into the V(2)O(5) films at very low temperatures, which is very important both for investigations of the reaction mechanism and for the optical properties of the V(2)O(5) films.

Cloning and characterisation of GIRK1 variants resulting from alternative RNA editing of the KCNJ3 gene transcript in a human breast cancer cell line.

The aim of this study was to investigate the impact of increased mRNA levels encoding GIRK1 in breast tumours on GIRK protein expression. mRNA levels encoding hGIRK1 and hGIRK4 in the MCF7, MCF10A and MDA-MB-453 breast cancer cell lines were assessed and the corresponding proteins detected using Western blots. cDNAs encoding for four hGIRK1 splice variants (hGIRK1a, 1c, 1d and 1e) were cloned from the MCF7 cell line.

Determination of phylloquinone and cholecalciferol encapsulated in granulates formed by melt extrusion.

Vitamin K1 (phylloquinone) and vitamin D3 (cholecalciferol) play a dominant role in bone metabolism. Both vitamins are sensitive to ultraviolet radiation, oxygen and other environmental influences. For this reason a special extrusion technology was developed, that enables an encapsulation of these sensitive substances in a matrix of carbohydrates and hydrogenated carbohydrates.

Fractal dimension of K1735 mouse melanoma clones and spheroid invasion in vitro.

An in vitro tumour-host confrontation method to investigate the invasion behaviour of cancer has been applied to K1735 mouse melanomas. Fluorescently labelled spheroids of cancer cells and host cells were confronted and the temporal course of cancer invasion into the host was investigated using confocal laser scanning microscopy. To improve the quantitative data of this method, the boundary images of the fluorescently labelled confrontation pairs were treated as fractals.

IK.ACh activation by arachidonic acid occurs via a G-protein-independent pathway mediated by the GIRK1 subunit.

The molecular target of arachidonic-acid-derived metabolites, serving as second messengers that activate atrial acetylcholine-activated potassium current (IK.ACh) in addition to G-protein beta/gamma subunits (Gbeta/gamma), is unknown. Co-expression of two isoforms of G-protein-activated, inwardly rectifying potassium channels (GIRKs) in oocytes of Xenopus laevis revealed that these heterologous co-expressed GIRKs, which are responsible for the formation of IK.

Efficacy of the novel calcium antagonist R(+)-semotiadil in limiting the ventricular rate during atrial flutter in isolated guinea pig hearts.

Ca2+ antagonists slow the ventricular rate by blocking conduction in the anterograde direction through the atrioventricular (AV) node. The aim of this study was to investigate the efficacy of the novel Ca2+ antagonist semotiadil compared with verapamil and diltiazem on the filtering capacity of the AV node during simulated atrial flutter in isolated guinea-pig hearts perfused by the method of Langendorff. During sinus rhythm, semotiadil as well as verapamil and diltiazem induced comparable depressant effects on AV-nodal conduction time and, during tachycardia, a comparable enhancement of this effect.

Cross-talk reduction in confocal images of dual fluorescence labelled cell spheroids.

Dual fluorescence labelling is an advanced method to separate two individual specimens in a biological system using confocal microscopy. An inherent problem of this method is fluorescence channel cross-talk, which causes problems for the exact spatial determination and separation of the specimens. Using a parallel fluorescence detection and an image processing technique, based on an image subtraction method, we have developed a very straight forward method for correcting the dual channel fluorescence images.

The cardiac acetylcholine-activated, inwardly rectifying K+-channel subunit GIRK1 gives rise to an inward current induced by free oxygen radicals.

Reactive oxygen species (ROS) play a crucial role in pathophysiology of the cardiovascular system. The present study was designed to analyze the redox sensitivity of G-protein-activated inward rectifier K+ (GIRK) channels, which control cardiac contractility and excitability. GIRK1 subunits were heterologously expressed in Xenopus laevis oocytes and the resulting K+ currents were measured with the two-electrode voltage clamp technique.

Hexadecylphosphocholine inhibits invasion of mouse T-cell lymphoma cells in two different invasion assays.

Hexadecylphosphocholine (HePC), an ether lipid analogue, is a new antineoplastic drug which has been shown to exert a remarkable antiproliferative effect in vitro and in vivo. The signal transduction pathway and the phospholipid synthesis are thought to be the main putative molecular targets of HePC, yet the exact mechanism of action is still unclear. To investigate the antiinvasive activity of HePC on a mouse T-cell lymphoma cell line (BW-O-Li1), we used a type I collagen gel and devitalized dermis as substrate to evaluate the migration of BW-O-Li1 after exposure to HePC.

Magnesium abolishes inadequate kinetics of frequency adaptation of the Q-aT interval in the presence of sotalol.

Objective: It has been well established that class III antiarrhythmic drugs can also induce ventricular arrhythmias. Marked changes in the QT interval are correlated with an increased dispersion of repolarization which is an important factor for the induction of ventricular arrhythmias. The aim of the present study was to investigate the effects of sotalol alone and in combination with MgSO4 and the Q-aT interval during abrupt changes in heart rate.

A novel benzothiazine Ca2+ channel antagonist, semotiadil, inhibits cardiac L-type Ca2+ currents.

The influence of semotiadil fumarate, a novel vasoselective Ca2+ channel antagonist with a benzothiazine skeleton, was measured on the high-threshold Ca2+ current ICa,L in guinea-pig ventricular myocytes prepared by coronary perfusion with collagenase solution. Patch- and voltage-clamp methods were used to measure ICa,L. Diltiazem, nifedipine and amlodipine were studied for comparison.

The "3R" concept in the Internet I.

More and more members of the scientific community interested in 3R related topics of animal experiments are using Internet-Homepages as a low-budget forum to present either their scientific results, or opinions on specific subjects or to announce publications. Supra/inter/national authorities/universities/laboratories are also offering information, documents, access to databases and much more to the interested public. Therefore the Internet is an advantageous new medium for 3R related subjects.

Interrelation of motility, cytoskeletal organization and gap junctional communication with invasiveness of melanocytic cells in vitro.

Intercellular communication and the active movement of malignant cells into and through host tissue barriers play a critical role during the complex process of tumor invasion. Motile activity, cytoskeletal actin and vinculin organization as well as gap junctional communication of in vivo benign and malignant melanocytes were compared and related to in vitro invasiveness. Normal melanocytes, Melan-a, showed significantly less motile activity, a higher organization of the actin cytoskeleton and more vinculin-containing cell-substratum adhesion plaques than highly metastatic melanoma cells, K1735-M2.

Influence of duration of rapid ventricular pacing on ventricular refractoriness in the presence of propafenone and lidocaine.

Propafenone and lidocaine have a rate dependent negative dromotropic effect on intraventricular conduction. We investigated the use dependent actions of propafenone and lidocaine on intraventricular conduction in isolated guinea pig hearts perfused by the method of Langendorff. Of primary interest was how the number of stimuli of the conditioning train (S1) might influence the ventricular effective refractory period (VERP) when refractoriness is assessed at a high pacing rate.

Differential effects of synthetic sphingosine derivatives on melanoma cell motility, growth, adhesion and invasion in vitro.

Cancer cell surface glycosphingolipids are considered to play a critical role in tumor growth and metastasis. However, the implications of glycoconjugates in the control of cell motility, which is considered to be involved in tumor invasion, are not fully understood. In this study, the effects of a series of synthetic sphingosine derivatives, obtained by the chemical transformation of azidosphingosines, on directional migration of K1735-M2 melanoma cells grown on type I collagen-coated surfaces were investigated.

Effects of AWD 23-111, a new antiarrhythmic substance, on cardiac conduction and refractoriness.

In isolated spontaneously beating guinea pig hearts, the effects of AWD 23-111 (N-(dicyclohexylcarbamoylmethyl)-N-(3-diethylamino-propyl)-4-nit robenzamid -hydrochloride), a new synthetic class III antiarrhythmic agent with sodium antagonistic properties, were investigated on cardiac electrophysiological parameters, that is, conduction and refractoriness. Concentration-dependent prolongation of the atrioventricular, intraventricular, and His bundle conduction times and of sinus node cycle length were present. At 0.

Flecainide alters the cardiac microscopic activation pattern. An in-vitro study using voltage sensitive dyes.

In order to evaluate whether flecainide may alter microscopic activation patterns, isolated guinea pig papillary muscles (paced at a rate of 1 Hz or 3 Hz respectively, superfused with saline Tyrode solution at 37 degrees C) were exposed to 1.5 mumol l-1 flecainide. The muscles were stained with the voltage sensitive dye di-4-ANEPPS and excited with argon ion laser light at 514 nm.

Rate-dependent effects of ajmaline and propafenone on atrioventricular conduction.

The aim of the present study was to characterize the time dependence of the depressant effects of ajmaline and propafenone on the Ca(2+)-channel-dependent tissue of the atrioventricular node in isolated guinea pig hearts perfused by the method of Langendorff. Ajmaline at a concentration of 0.03 microM and propafenone at a concentration of 0.

Effects of verapamil and diltiazem on the ventricular rate during simulated atrial flutter in isolated guinea pig hearts.

To compare the direct effects of verapamil and diltiazem on the ventricular rate during atrial flutter, we developed an atrial flutter model in guinea pig isolated hearts. Atrial flutter was simulated by rapid atrial pacing (cycle length = 50 ms). At this atrial pacing cycle length, the shape of the frequency of distribution of the ventricular cycle lengths was comparable to that during spontaneous atrial flutter.