Intracellular free sodium and potassium, post-carbachol hyperpolarization, and extracellular potassium-undershoot in rat sympathetic neurones

Double-barrelled ion-sensitive microelectrodes were used to record the free intracellular Na+- and K+-concentrations ([Na+]i, [K+]i) and to determine their relation to changes in membrane potential and extracellular K+ ([K+]e) in rat sympathetic ganglia. The application of 50 μmol/l carbachol resulted in an elevation of [K+]e followed by a post-carbachol [K+]e-undershoot. The membrane depolarization of the sympathetic neurones was associated with an increase in [Na+]i and a decrease in [K+]i. A membrane hyperpolarization and a recovery of [K+]i and [Na+]i to their baseline levels were observed during the [K+]e-undershoot. The time course of the [K+]e-undershoot correlated exactly with the duration of the rise in [Na+]i and decrease of [K+]i. No K+-reuptake occurred in the presence of ouabain. These data confirm, by direct measurements of intracellular ion concentration changes, the contribution of the Na+, K+-pump to the post-carbachol membrane hyperpolarization and [K+]e-undershoot

Proton Fall or Bicarbonate Rise: Glycolytic Rate In Mouse Astrocytes Is Paved By Intracellular Alkalinization

Glycolysis is the primary step for major energy production in the cell. There is strong evidence suggesting that glucose consumption and rate of glycolysis are highly modulated by cytosolic pH/[H(+)], but those can also be stimulated by an increase in the intracellular [HCO3 (-)]. Because proton and bicarbonate shift concomitantly, it remained unclear whether enhanced glucose consumption and glycolytic rate were mediated by the changes in intracellular [H(+)] or [HCO3 (-)]. We have asked whether glucose metabolism is enhanced by either a fall in intracellular [H(+)] or a rise in intracellular [HCO3 (-)], or by both, in mammalian astrocytes. We have recorded intracellular glucose in mouse astrocytes using a FRET-based nanosensor, while imposing different intracellular [H(+)] and [CO2]/[HCO3 (-)]. Glucose consumption and glycolytic rate were augmented by a fall in intracellular [H(+)], irrespective of a concomitant rise or fall in intracellular [HCO3 (-)]. Transport of HCO3 (-) into and out of astrocytes by the electrogenic sodium bicarbonate cotransporter (NBCe1) played a crucial role in causing changes in intracellular pH and [HCO3 (-)], but was not obligatory for the pH-dependent changes in glucose metabolism. Our results clearly show that it is the cytosolic pH that modulates glucose metabolism in cortical astrocytes, and possibly also in other cell types

The role of MscL amphipathic N terminus indicates a blueprint for bilayer-mediated gating of mechanosensitive channels

The bacterial mechanosensitive channel MscL gates in response to membrane tension as a result of mechanical force transmitted directly to the channel from the lipid bilayer. MscL represents an excellent model system to study the basic biophysical principles of mechanosensory transduction. However, understanding of the essential structural components that transduce bilayer tension into channel gating remains incomplete. Here using multiple experimental and computational approaches, we demonstrate that the amphipathic N-terminal helix of MscL acts as a crucial structural element during tension-induced gating, both stabilizing the closed state and coupling the channel to the membrane. We propose that this may also represent a common principle in the gating cycle of unrelated mechanosensitive ion channels, allowing the coupling of channel conformation to membrane dynamics

Developing work based personal learning environments in small and medium enterprises

This paper is based on a literature review and interviews with employers and trainers in the north German building and construction trades. The work was undertaken in preparing a project application, Learning Layers, for the European Research Programme. The paper looks at the development of High Performance Work Systems to support innovation in Small and Medium enterprises. It discusses the potential of Personal Learning environments to support informal and work based learning. The paper goes on to look at the characteristics and organisation of the building and construction industry and at education and training in the sector. It outlines an approach to developing the use of PLEs based on a series of layers to support informal interactions with people across enterprises, supports creation, maturing and interaction with learning materials as boundary objects and a layer that situates and scaffolds learning support into the physical workplace and captures people’s interactions with physical artefacts inviting them to share their experiences.&nbsp

A Cl- cotransporter selective for NH4+ over K+ in glial cells of bee retina

There appears to be a flux of ammonium (NH4+/NH3) from neurons to glial cells in most nervous tissues. In bee retinal glial cells, NH4+/NH3 uptake is at least partly by chloride-dependant transport of the ionic form NH4+. Transmembrane transport of NH4+ has been described previously on transporters on which NH4+ replaces K+, or, more rarely, Na+ or H+, but no transport system in animal cells has been shown to be selective for NH4+ over these other ions. To see if the NH4+-Cl− cotransporter on bee retinal glial cells is selective for NH4+ over K+ we measured ammonium-induced changes in intracellular pH (pHi) in isolated bundles of glial cells using a fluorescent indicator. These changes in pHi result from transmembrane fluxes not only of NH4+, but also of NH3. To estimate transmembrane fluxes of NH4+, it was necessary to measure several parameters. Intracellular pH buffering power was found to be 12 mM. Regulatory mechanisms tended to restore intracellular [H+] after its displacement with a time constant of 3 min. Membrane permeability to NH3 was 13 μm s−1. A numerical model was used to deduce the NH4+ flux through the transporter that would account for the pHi changes induced by a 30-s application of ammonium. This flux saturated with increasing [NH4+]o; the relation was fitted with a Michaelis-Menten equation with Km ≈ 7 mM. The inhibition of NH4+ flux by extracellular K+ appeared to be competitive, with an apparent Ki of ∼15 mM. A simple standard model of the transport process satisfactorily described the pHi changes caused by various experimental manipulations when the transporter bound NH4+ with greater affinity than K+. We conclude that this transporter is functionally selective for NH4+ over K+ and that the transporter molecule probably has a greater affinity for NH4+ than for K+

Status quo of digital accessibility in multinational enterprises: An exploratory study

Digital accessibility (DA) for disabled people is a hot topic, mandatory under UN and EU dispositions. Literature shows a research gap regarding relevant factors that influence the enforcement of DA in Multinationals (MNEs) (RQ1) in order to structure the problem. An exploratory study analysed the current status of DA in MNEs. Findings were consolidated by comparing them with experiences reported by FCEA conference of experts, confirming a notable deficiency in current literature regarding DA status-quo (RQ2). A normative approach, grounded in legal, legitimate, and ethical standards to steer corporate governance in matters of DA was proposed following Soft Systems Methodology.info:eu-repo/semantics/publishedVersio

Easytube, Laryngeal tube S, ProSeal Laryngeal mask: extraglottic airway devices in comparison to the endotracheal tube

Eine klinisch randomisierte Studie an 120 Patienten zu Beatmungs- und Vitalparametern, Systemdichtigkeit in Abhängigkeit von Cuffdruck und Cuffvolumen, Handhabung bei dem Anwender und postoperative Patientenzufriedenheit

Die Pflege im Spannungsfeld: Das Entstehen ethischer Konfliktsituationen in der Langzeitpflege im Kontext von COVID-19 – eine empirische Untersuchung

kein Abstract vorhande

Entwicklungsperspektiven rindviehhaltender Betriebe in NRW

Die EU-Agrarreform von 2003 sieht eine Entkopplung der Beihilfen an die Landwirtschaft von der Produktion vor. Die nationale Ausgestaltung dieser Reform in Deutschland in Form des Kombinationsmodells entzieht der Rinderhaltung die Tierprämien. Ziel der vorliegenden Arbeit ist die Darstellung von Entwicklungsperspektiven rindviehhaltender Betriebe in NRW unter den geänderten Rahmenbedingungen. Das Forschungsvorhaben wird in Form einer Panelbefragung durchgeführt. Dabei wird der Ansatz typischer Betriebe genutzt. Es werden fünf typische Betriebe mit Rinderhaltung in Zusammenarbeit mit den Spezialberatern der Landwirtschaftskammer ausgewählt. Dies sind ein Bullenmastbetrieb, ein Bullen- und Schweinemastbetrieb, ein Milchviehbetrieb mit Bullenmast, ein extensiver Milchviehbetrieb und ein Mutterkuhbetrieb. Diese Modellbetriebe bilden ein Testbetriebsnetz, das als Datengrundlage für die Forschungsfragestellungen dient. Dazu wird für jeden Betrieb ein Panel zur Befragung und Diskussion eingerichtet. Zur Analyse der Entwicklungsperspektiven der einzelnen Haltungsformen für Rinder wird ein Kalkulationsmodell entwickelt, das auf der Grundlage von Leistungs- und Kostenrechnungen Betriebszweigauswertungen erstellt. Dieses Modell bildet die typischen Betriebe mit Rinderhaltung auf der Ebene der einzelnen Betriebszweige über einen Betrachtungshorizont von zehn Jahren ab. Darüber hinaus sind die gesamtbetrieblichen Auswirkungen ersichtlich. Durch diese Vorgehensweise werden kurz- und langfristige Auswirkungen unterschiedlicher Annahmen aufgezeigt. Um verschiedene Fragestellungen in Bezug auf die Rindviehhaltung zu untersuchen, werden Szenarien gebildet, um die Auswirkungen der Annahmen unmittelbar zu simulieren. Zur Bestimmung der Effekte von agrarpolitischen Veränderungen sowie zur Darstellung der Bedeutung von Marktgeschehnissen auf die rindviehhaltenden Betriebe, werden verschiedene Szenarien getrennt von einander untersucht. Betrachtet werden insbesondere verschiedene Politik- und Preisszenarien. Die Ergebnisse der Szenarienrechnungen werden auf der Basis von Direktkostenfreier Leistung und Kalkulatorischem Betriebszweigergebnis sowohl auf Ebene des Gesamtbetriebes als auch auf Ebene der Betriebszweige betrachtet. In einem separaten Hochrechnungsmodul werden die Ergebnisse der Modellrechnungen in ihren Auswirkungen auf die Struktur der Rinderhaltungen in NRW abgebildet. Die Rinderhaltung in NRW ist durch die Entkopplung in der Mid-term Reform stark betroffen. Die Anzahl der Halter wird nach den Berechnungen bis 2014 um 40 % und die Anzahl der Rinder um 23,5 % zurückgehen. Sinken die Rindfleischpreise stärker ab, wird sich diese Entwicklung verstärken.Prospects of cattle farms in North Rhine Westfalia The CAP Reform in the European Union in 2003 decouples the granting of subsidies from production. In Germany the national implementation of this reform withdraws the payments for animals from the production in particular for cattle. The objective of this study is to analyse the prospects of cattle farms in North Rhine Westfalia (NRW). The research project is based on a panel survey. Thereby the approach of typical farms is used. Five typical cattle farms are selected in cooperation with the experts of the official consulting. These typical farms include a bull fattening production farm, a production farm with bull- and pig fattening, a dairy production farm with bull fattening, an extensive dairy production farm and a suckler cow farm. Data sets of these farms are used to build a network of test farms as database for further research work. For every typical farm an advisory board of farmers belonging to the same production type is installed. Meetings with these groups are used to interrogate the farmers, to discuss special questions and finally to validate the simulation results. A model is developed based on cost accounting and results accounts for each farm enterprise entity to analyse the perspectives of the different cattle production systems. The model simulates the typical cattle farms on farm entity level. These typical farms are mapped on their accountancy on farm level by the use of the described calculation model over a ten years period. Furthermore the entire farm effects are apparent. Due to this approach, it is possible to demonstrate the short term and the long term impacts of different assumptions. To investigate different questions with relation to cattle farming assumptions are made and these scenarios are included in the calculation model to simulate the effects directly on farm level. Different assumptions for changes in agricultural policy and changes of the markets are investigated separately regarding their impacts on the typical farms. The outcome of these scenario calculations are compared on different accounting levels for the farm enterprise entity as well as on entire farm level. The results where aggregated by a separately developed exploration tool to demonstrate the impact on the farm structure in NRW. The cattle production in NRW is extremely affected by the decoupling of the Midterm Reform. According to the calculations the number of cattle owner will decrease until 2014 by 40 % and the number of cattle by 23.5 %. In case of declining cattle meat prices the described development will be more intensive